Patent Publication Number: US-11034155-B2

Title: Liquid reservoir unit, liquid ejecting apparatus, and maintenance method for liquid ejecting apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2018-170575, filed Sep. 12, 2018 and JP Application Serial Number 2018-214772, filed Nov. 15, 2018, the disclosures of which are hereby incorporated by reference herein in their entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a liquid reservoir unit configured to store a liquid, a liquid ejecting apparatus including a liquid reservoir unit, and a maintenance method for a liquid ejecting apparatus. 
     2. Related Art 
     JP-A-2000-263807 discloses, as an example of a liquid ejecting apparatus, an ink jet recording apparatus including a sub-tank which is an example of a liquid reservoir unit. The sub-tank is configured to store ink which is an example of a liquid. The ink jet recording apparatus records an image on a medium by ejecting a liquid stored in the sub-tank. 
     In the ink jet recording apparatus disclosed in JP-A-2000-263807, components of the liquid may settle in the sub-tank. When the components of the liquid settle, unevenness of the concentration is generated, which affects the recording quality. 
     SUMMARY 
     A liquid reservoir unit for solving the above problem includes a reservoir portion configured to store a liquid; an outflow portion disposed at a position near a first end of the reservoir portion and configured to cause the liquid to flow out of the reservoir portion; and an inflow portion disposed at a position near the first end of the reservoir portion and configured to cause the liquid to flow into the reservoir portion. The outflow portion includes an outflow opening opened to an interior of the reservoir portion, and the inflow portion includes an inflow opening opened to the interior of the reservoir portion. The outflow opening and the inflow opening are located at different positions in a width direction which is a lengthwise direction of the reservoir portion when the reservoir portion is viewed from the first end, and also located at different positions in a depth direction from the first end toward a second end on the opposite side to the first end. 
     A liquid ejecting apparatus for solving the above problem includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; a liquid reservoir unit having a reservoir portion that is provided in the liquid supply flow path and is configured to store the liquid; a discharge mechanism configured to discharge the liquid in the liquid supply flow path from a side of the liquid ejecting portion relative to the reservoir portion in the liquid supply flow path by depressurizing the liquid supply flow path; and a control portion configured to control the discharge mechanism to discharge the liquid staying in the reservoir portion as a waste liquid when a stay of the liquid in the reservoir portion exceeds a set time. 
     A maintenance method for a liquid ejecting apparatus for solving the above problem is a maintenance method for the liquid ejecting apparatus that includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; and a liquid reservoir unit having a reservoir portion that is provided in the liquid supply flow path and is configured to store the liquid. The method includes discharging the liquid staying in the reservoir portion as a waste liquid when a stay of the liquid in the reservoir portion exceeds a set time. 
     A liquid ejecting apparatus for solving the above problem includes a liquid ejecting portion configured to eject a liquid through a nozzle; a holding portion configured to attach and detach a liquid supply source for containing the liquid; a liquid supply flow path configured to supply the liquid from the liquid supply source attached to the holding portion to the liquid ejecting portion; a reservoir portion provided in the liquid supply flow path and configured to store the liquid; a reservoir amount adjustment mechanism configured to adjust a reservoir amount of the liquid stored in the reservoir portion; and a control portion configured to control the reservoir amount adjustment mechanism in such a manner that, when an upper limit value of the reservoir amount is defined as a first upper limit value in a case in which a remaining amount of the liquid contained in the liquid supply source is equal to or smaller than a predetermined value, the reservoir amount when the remaining amount is larger than the predetermined value is caused to be smaller than the first upper limit value. 
     A control method for a liquid ejecting apparatus for solving the above problem is a control method for the liquid ejecting apparatus that includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; and a reservoir portion provided in the liquid supply flow path and configured to store the liquid. The method includes, when an upper limit value of a reservoir amount of the liquid stored in the reservoir portion is defined as a first upper limit value in a case in which a remaining amount of the liquid contained in the liquid supply source is equal to or smaller than a predetermined value, performing adjustment in such a manner that the reservoir amount when the remaining amount is larger than the predetermined value is caused to be smaller than the first upper limit value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a first embodiment of a liquid ejecting apparatus. 
         FIG. 2  is a side view schematically illustrating an internal structure of a liquid ejecting apparatus. 
         FIG. 3  is a schematic diagram illustrating a configuration of a liquid ejecting apparatus and a liquid supply device. 
         FIG. 4  is a perspective view of a liquid reservoir unit and a holding portion. 
         FIG. 5  is a cross-sectional view of a liquid reservoir unit and a holding portion. 
         FIG. 6  is a cross-sectional view taken along a line VI-VI in  FIG. 5 . 
         FIG. 7  is a front view of a reservoir portion in an inflated state when seen from a first end. 
         FIG. 8  is a front view of a reservoir portion in a deflated state when seen from a first end. 
         FIG. 9  is a flowchart of a printing process. 
         FIG. 10  is a schematic diagram illustrating a modification of a liquid reservoir unit. 
         FIG. 11  is a schematic diagram illustrating another modification of a liquid reservoir unit. 
         FIG. 12  is a schematic diagram illustrating a second embodiment of a configuration of a liquid ejecting apparatus and a liquid supply device. 
         FIG. 13  is a cross-sectional view of a liquid reservoir unit of the second embodiment taken along the line XIII-XIII in  FIG. 5 . 
         FIG. 14  is a schematic diagram of a liquid ejecting apparatus when a remaining amount is larger than a predetermined amount. 
         FIG. 15  is a flowchart illustrating a liquid supply routine. 
         FIG. 16  is a schematic diagram illustrating a third embodiment of a liquid ejecting apparatus. 
         FIG. 17  is a schematic diagram illustrating a modification of a liquid ejecting apparatus. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment of a liquid ejecting apparatus will be described with reference to the drawings. A liquid ejecting apparatus is, for example, an ink jet printer configured to print an image such as characters or photographs by ejecting ink, which is an example of a liquid, onto a medium such as paper. 
     As illustrated in  FIG. 1 , a liquid ejecting apparatus  10  includes a pair of leg portions  11  and a housing  12  mounted on the leg portions  11 . The liquid ejecting apparatus  10  is provided with a feeding portion  13  configured to feed out a medium M wound on a roll body into the housing  12 , a guide portion  14  configured to guide the medium M discharged from the housing  12 , and a winding portion  15  configured to wind the medium M guided by the guide portion  14  on a roll body. The liquid ejecting apparatus  10  includes a tension applying mechanism  16  configured to give tension to the medium M to be wound by the winding portion  15 , and an operation panel  17  to be operated by a user. 
     The liquid ejecting apparatus  10  has predetermined lengths as its width, depth, and height in a state of being installed on a place where it is used. The direction of gravity is indicated by a Z-axis, assuming that the liquid ejecting apparatus  10  is disposed on a horizontal plane. At this time, the width direction and the depth direction of the liquid ejecting apparatus  10  are substantially horizontal. The width direction of the liquid ejecting apparatus  10  is indicated by an X-axis. The X-axis, an Y-axis, and the Z-axis are orthogonal to each other. Therefore, the X-axis, the Y-axis, and the Z-axis are coordinate axes indicating the width, depth, and height of the liquid ejecting apparatus  10 , respectively. 
     As illustrated in  FIG. 2 , the liquid ejecting apparatus  10  includes a support base  20  for supporting the medium M, and a transportation portion  30  for transporting the medium M. The liquid ejecting apparatus  10  includes a printing portion  40  configured to print on the medium M, and a control portion  60  configured to control operations of the liquid ejecting apparatus  10 . The liquid ejecting apparatus  10  is provided with a liquid supply device  100  configured to supply a liquid to the printing portion  40 . The control portion  60  is configured to include, for example, a CPU, a memory, and the like. The control portion  60  controls the liquid ejecting apparatus  10  and the liquid supply device  100  by the CPU executing a program stored in the memory. 
     The support base  20  is so provided as to extend in the width direction of the liquid ejecting apparatus  10 . In the present embodiment, the width direction of the liquid ejecting apparatus  10  is coincident with the width direction of the medium M. The medium M is transported in a direction opposite to the depth direction of the liquid ejecting apparatus  10  on the support base  20 . Therefore, the transportation direction of the medium M is opposite to the depth direction of the liquid ejecting apparatus  10 . 
     The transportation portion  30  includes a pair of transportation rollers  31  located upstream of the support base  20  in the transportation direction, and a pair of transportation rollers  32  located downstream of the support base  20 . The transportation portion  30  is provided with a transportation motor  33  for driving the pair of transportation rollers  31  and the pair of transportation rollers  32 . When the pair of transportation rollers  31  and the pair of transportation rollers  32  are driven by the transportation motor  33 , the medium M pinched between the pair of transportation rollers  31  and between the pair of transportation rollers  32  is transported in the transportation direction along a surface of the support base  20 . 
     The printing portion  40  includes a liquid ejecting portion  41  configured to eject a liquid through a nozzle  44 . The printing portion  40  of the present embodiment includes a guide shaft  42  provided in such a manner as to extend in the width direction, and a carriage  43  configured to reciprocate in the width direction by being guided by the guide shaft  42 . 
     The printing portion  40  is provided with a carriage motor  45  for moving the carriage  43  along the guide shaft  42 . The carriage  43  is moved in accordance with the driving of the carriage motor  45 . That is, the liquid ejecting apparatus  10  of the present embodiment is a serial type apparatus in which the liquid ejecting portion  41  scans with respect to the medium M. The liquid ejecting apparatus  10  may be configured as a line type apparatus in which the liquid ejecting portion  41  is provided having a long size in the width direction. 
     As illustrated in  FIG. 3 , the liquid ejecting portion  41  includes one or a plurality of nozzles  44  for ejecting a liquid. The liquid ejecting portion  41  includes an individual liquid chamber  411  communicating with the nozzle  44 , an accommodation portion  413  separated by a vibration plate  412  from the individual liquid chamber  411 , and an actuator  414  accommodated in the accommodation portion  413 . The liquid ejecting portion  41  is provided with a common liquid chamber  415  for temporarily storing the supplied liquid and supplying the liquid to a plurality of individual liquid chambers  411 . 
     The actuator  414  is, for example, a piezoelectric element configured to contract when a drive voltage is applied thereto. After the vibration plate  412  is deformed with the contraction of the actuator  414 , when the application of the drive voltage is stopped, the liquid in the individual liquid chamber  411  whose volume has been changed is ejected as a droplet through the nozzle  44 . 
     The liquid ejecting apparatus  10  includes a liquid supply flow path  110  and a liquid reservoir unit  120  as constituent elements of the liquid supply device  100 . The liquid supply flow path  110  is configured to supply a liquid contained in a liquid supply source  101  to the liquid ejecting portion  41 . The liquid supply flow path  110  couples the liquid ejecting portion  41  to the liquid supply source  101  serving as a liquid supply source to the liquid ejecting portion  41 . The liquid supply flow path  110  is configured to include, for example, a tube. 
     The liquid reservoir unit  120  includes a reservoir portion  121  configured to store a liquid. The liquid reservoir unit  120  is provided in the liquid supply flow path  110 . The liquid reservoir unit  120  is located between the liquid supply source  101  and the liquid ejecting portion  41  in the liquid supply flow path  110 . The liquid reservoir unit  120  stores a liquid supplied from the liquid supply source  101 . Therefore, the liquid reservoir unit  120  is located downstream of the liquid supply source  101  in the direction in which the liquid is supplied. 
     The reservoir portion  121  may be formed of a bag-like member  122  having flexibility. The liquid reservoir unit  120  of the present embodiment includes the reservoir portion  121  formed of the bag-like member  122 , and a connection body  123  configured to be coupled to the liquid supply flow path  110 . The liquid supplied from the liquid supply source  101  is stored in the reservoir portion  121  through the connection body  123 . Since the reservoir portion  121  is formed of the bag-like member  122 , it is inflated or deflated in accordance with the amount of the liquid that is stored. That is, the volume of the reservoir portion  121  changes by being inflated or deflated. 
     The liquid reservoir unit  120  may be configured to store a predetermined amount or more than a predetermined amount of liquid while the liquid is supplied from the liquid supply source  101 . The predetermined amount is an amount which is expected to be used for printing one image. With this, even when the liquid in the liquid supply source  101  is exhausted during the printing of an image, the printing of the image may be continued by using the liquid stored in the liquid reservoir unit  120 . This reduces a risk of the interruption of printing. Further, it is possible to suppress deterioration in print quality such as color unevenness due to the interruption of printing. 
     When a remaining amount of the liquid contained in the liquid supply source  101  becomes 0 or significantly small, the liquid is supplied to the liquid ejecting portion  41  from the liquid reservoir unit  120 . Therefore, while a sufficient amount of liquid is contained in the liquid supply source  101 , the amount of the liquid stored in the liquid reservoir unit  120  hardly changes. When the amount of the liquid contained in the liquid supply source  101  becomes small, the amount of the liquid stored in the liquid reservoir unit  120  starts to decrease. In the liquid reservoir unit  120  of the present embodiment, when the reservoir portion  121  is inflated to its maximum, a predetermined amount or more than a predetermined amount of liquid is stored. 
     In the present embodiment, the liquid is supplied to the liquid reservoir unit  120  by being pressurized from the liquid supply source  101  side. Therefore, while the sufficient amount of liquid is contained in the liquid supply source  101 , the reservoir portion  121  is maintained in an inflated state by being pressurized from the upstream. As a result, the liquid reservoir unit  120  stores a predetermined amount or more than a predetermined amount of liquid therein while the liquid is supplied from the liquid supply source  101 . 
     The liquid ejecting apparatus  10  may include an on-off valve  140  and a pressure mechanism  150  as constituent elements of the liquid supply device  100 . The on-off valve  140  is configured to open and close the liquid supply flow path  110 . The on-off valve  140  is disposed in the liquid supply flow path  110 . The on-off valve  140  of the present embodiment is disposed on the liquid supply source  101  side relative to the liquid reservoir unit  120  in the liquid supply flow path  110 . Therefore, the on-off valve  140  is located between the liquid reservoir unit  120  and the liquid supply source  101  in the liquid supply flow path  110 . When the on-off valve  140  is opened, it is possible for the liquid to flow from the liquid supply source  101  toward the liquid reservoir unit  120 . When the on-off valve  140  is closed, the flow of the liquid from the liquid supply source  101  toward the liquid reservoir unit  120  is blocked. 
     The on-off valve  140  may be, for example, a solenoid valve configured to open and close the valve by a solenoid, or a motor-operated valve configured to open and close the valve by an electric motor. The on-off valve  140  may be a fluid pressure valve configured to open and close the valve by a fluid pressure cylinder, or may be another type of control valve. 
     The pressure mechanism  150  is configured to apply a negative pressure to the interior of the reservoir portion  121  from the exterior. In order to apply the negative pressure to the interior of the reservoir portion  121  from the exterior, the pressure mechanism  150  of the present embodiment inflates the reservoir portion  121  in such a manner as to increase the volume of the reservoir portion  121 . 
     The pressure mechanism  150  of the present embodiment inflates the reservoir portion  121  to increase the volume of the reservoir portion  121  by depressurizing the outside the reservoir portion  121 . When the reservoir portion  121  is inflated, the pressure inside the reservoir portion  121  is reduced. In this manner, the pressure mechanism  150  applies a negative pressure to the interior of the reservoir portion  121  from the outside of the reservoir portion  121 . The pressure mechanism  150  may be configured to apply a negative pressure from the exterior to the interior of the reservoir portion  121  by inflating the reservoir portion  121  by using a mechanical element such as a spring or a lever. 
     The pressure mechanism  150  may include a holding portion  152  having a pressure chamber  151  for accommodating the reservoir portion  121 , and a pump  153  for depressurizing the interior of the pressure chamber  151 . The pressure mechanism  150  depressurizes the interior of the pressure chamber  151  by using the pump  153 , thereby applying a negative pressure to the interior of the reservoir portion  121  from the exterior. When the interior of the pressure chamber  151  is depressurized, the reservoir portion  121  is inflated. As a result, a negative pressure is applied from the outside of the reservoir portion  121  to the interior of the reservoir portion  121 . The inflated reservoir portion  121  makes contact with an inner wall  154  of the holding portion  152  forming the pressure chamber  151 . The reservoir portion  121 , when storing a predetermined amount or more than a predetermined amount of liquid therein, comes into contact with the inner wall  154  of the holding portion  152 . 
     The pressure mechanism  150  of the present embodiment may also pressurize the interior of the pressure chamber  151 . When the interior of the pressure chamber  151  is pressurized, the reservoir portion  121  is deflated. The pressure mechanism  150  adjusts the pressure inside the reservoir portion  121  by depressurizing and pressurizing the interior of the pressure chamber  151 . The pressure mechanism  150  may be configured to open the pressure chamber  151  to the atmosphere. 
     The pressure mechanism  150  may include a pressure adjustment flow path  155  coupling the pressure chamber  151  and the pump  153  located outside the holding portion  152 . The pump  153  pressurizes or depressurizes the pressure chamber  151  through the pressure adjustment flow path  155 . The pump  153  may be located inside the holding portion  152 . 
     The liquid ejecting apparatus  10  includes a discharge mechanism  50  configured to depressurize the liquid supply flow path  110 . The discharge mechanism  50  is configured to discharge a liquid in the liquid supply flow path  110  from the liquid ejecting portion  41  side relative to the reservoir portion  121  in the liquid supply flow path  110  by depressurizing the liquid supply flow path  110 . 
     The discharge mechanism  50  of the present embodiment includes a cap  51  configured to cover the nozzle  44  of the liquid ejecting portion  41 , and a suction pump  52  for sucking stuff inside the cap  51 . The cap  51  is brought into contact with the liquid ejecting portion  41 , thereby capping the liquid ejecting portion  41 . The capping is to form a space in which the nozzle  44  opens. The capping is performed to suppress drying of the nozzle  44 , or the like. 
     When the suction pump  52  is driven while the cap  51  capping the liquid ejecting portion  41 , a negative pressure is applied to the nozzle  44  so that the liquid is forcibly discharged through the nozzle  44 . This is called suction cleaning. In other words, the discharge mechanism  50  of the present embodiment depressurizes the liquid supply flow path  110  through the liquid ejecting portion  41 , so as to discharge the liquid in the liquid supply flow path  110  as a waste liquid from the liquid ejecting portion  41 . 
     When the suction cleaning is performed, bubbles, foreign objects, and the like within the liquid ejecting portion  41  and the liquid supply flow path  110  are discharged together with the liquid. Therefore, the discharge mechanism  50  depressurizes the liquid supply flow path  110  in order to maintain the liquid ejecting apparatus  10 . 
     The discharge mechanism  50  may include a waste liquid tank  53  for collecting the waste liquid discharged from the liquid ejecting portion  41 . With this, for example, the waste liquid having been discharged to the cap  51  by the suction cleaning can be collected by the waste liquid tank  53 . The waste liquid tank  53  may directly collect the discharged waste liquid. 
     The discharge mechanism  50  may include a regulator  54  for adjusting the pressure inside the cap  51 . The regulator  54  allows the interior of the cap  51  to communicate with the atmosphere so that the pressure inside the cap  51  is set to a predetermined pressure, which is, for example, −2 kPa to +2 kPa at the capping time. That is, the regulator  54  adjusts the pressure inside the cap  51  to a predetermined pressure by introducing air into the cap  51 . The regulator  54  may be an open air valve which is closed when a negative pressure is applied to the nozzle  44 , and opened when the interior of the cap  51  is allowed to communication with the atmosphere. 
     The liquid ejecting apparatus  10  may be configured to perform a maintenance operation in which the liquid supply flow path  110  is depressurized by the discharge mechanism  50  in a state in which the liquid supply flow path  110  is closed by the on-off valve  140 . When the liquid supply flow path  110  is depressurized by the discharge mechanism  50  in a state in which the liquid supply flow path  110  is closed by the on-off valve  140 , a negative pressure is accumulated in a portion of the liquid supply flow path  110  downstream of the on-off valve  140 . When the negative pressure is accumulated in the liquid supply flow path  110 , the volume of the bubble in the liquid supply flow path  110  is increased. As a result, the bubbles in the liquid supply flow path  110  are likely to be discharged. 
     In the present embodiment, the liquid is discharged through the nozzle  44  by opening the on-off valve  140  in a state where the negative pressure is accumulated in the liquid supply flow path  110 . As discussed above, the operation in which a negative pressure generated by the discharge mechanism  50  depressurizing the liquid supply flow path  110  is accumulated first, and then the liquid in the liquid supply flow path  110  is vigorously discharged through the nozzle  44  by the accumulated negative pressure, is generally referred to as choke cleaning. The choke cleaning is performed to maintain the liquid ejecting apparatus  10 . When the choke cleaning is performed, bubbles, foreign objects, and the like in the liquid ejecting portion  41  and in the liquid supply flow path  110  are discharged together with the liquid. The choke cleaning is performed mainly for the purpose of discharging the bubbles, foreign objects, and the like in the liquid supply flow path  110 . 
     In the liquid ejecting apparatus  10  of the present embodiment, when the choke cleaning is to be performed, the on-off valve  140  is closed first. Subsequently, the liquid supply flow path  110  is depressurized from the liquid ejecting portion  41  side by the discharge mechanism  50 . With this, a negative pressure is accumulated in a portion of the liquid supply flow path  110  closer to the liquid ejecting portion  41  relative to the on-off valve  140 , that is, in a portion of the liquid supply flow path  110  located downstream of the on-off valve  140 . Next, the on-off valve  140  is opened. As a result, the liquid is vigorously discharged through the nozzle  44  by the depressurization of the discharge mechanism  50 . 
     In the maintenance operation, when the liquid supply flow path  110  is depressurized by the discharge mechanism  50  in a state where the liquid supply flow path  110  is closed by the on-off valve  140 , the reservoir portion  121  is also depressurized. When a negative pressure is applied to the interior of the reservoir portion  121  by the depressurization of the discharge mechanism  50 , the liquid flows out of the reservoir portion  121  in some cases. In this case, the liquid stored in the reservoir portion  121  is consequently discharged in order to discharge the bubbles, foreign objects, and the like in the liquid supply flow path  110 . Therefore, the amount of liquid consumption involved in the maintenance is increased. 
     When the liquid flows out of the reservoir portion  121  by the depressurization of the discharge mechanism  50 , a negative pressure is unlikely to be accumulated in the liquid supply flow path  110 . In particular, in a case in which the reservoir portion  121  is formed of the bag-like member  122 , when the depressurization by the discharge mechanism  50  is applied to the interior of the reservoir portion  121 , the reservoir portion  121  is deflated so that its volume becomes smaller. In this case, when it is attempted to accumulate a sufficient negative pressure in the liquid supply flow path  110 , most of the liquid in the reservoir portion  121  flows out resulting from the deflation of the reservoir portion  121 . In other words, when the choke cleaning is performed in such a state, since most of the liquid stored in the reservoir portion  121  is discharged, the amount of liquid consumption is likely to become large. 
     The liquid ejecting apparatus  10  may operate in such a manner as to reduce the amount of liquid consumption in the maintenance operation. For example, in the maintenance operation, the control portion  60  may control the pressure mechanism  150  so that a negative pressure equal to or larger than a negative pressure applied to the interior of the reservoir portion  121  by the depressurization of the discharge mechanism  50  is applied to the interior of the reservoir portion  121 . At this time, the negative pressure applied to the interior of the reservoir portion  121  by the depressurization of the discharge mechanism  50  is, for example, −50 kPa with respect to the atmospheric pressure. In the maintenance operation, the control portion  60  controls the pressure mechanism  150  so that a negative pressure of −60 kPa, for example, is applied to the interior of the reservoir portion  121  as a negative pressure equal to or larger than −50 kPa. In other words, the pressure mechanism  150  acts to apply a pressure smaller than the pressure applied to the interior of the reservoir portion  121  by the depressurization of the discharge mechanism  50 , to the interior of the reservoir portion  121  from the exterior. This reduces a risk that the liquid flows out of the reservoir portion  121  due to the depressurization of the discharge mechanism  50 . 
     In the maintenance operation, the pressure mechanism  150  of the present embodiment acts to apply a negative pressure to the interior of the reservoir portion  121  from the exterior in such a manner that the reservoir portion  121  is not deflated due to the depressurization of the discharge mechanism  50 . For example, in the maintenance operation, the pressure mechanism  150  depressurizes the pressure chamber  151  so that the reservoir portion  121  makes contact with the inner wall  154  of the holding portion  152 . With this, in the maintenance operation, it is possible to maintain the amount of the liquid stored in the reservoir portion  121  at a level of a predetermined amount or more than a predetermined amount. 
     The pressure mechanism  150  pressurizes the interior of the reservoir portion  121  by sending a gas to the pressure chamber  151  when the empty reservoir portion  121  is to be filled with the liquid. When the interior of the reservoir portion  121  is pressurized, the air in the reservoir portion  121  is discharged. This makes it possible for the reservoir portion  121  to be filled with the liquid. The pressure mechanism  150  acts in such a manner that, when the amount of the liquid in the liquid supply source  101  becomes small, the liquid is supplied from the reservoir portion  121  by starting to pressurize the interior of the reservoir portion  121 . 
     Next, the liquid supply device  100  of the present embodiment will be described. 
     The liquid supply device  100  may include a liquid supply source holding portion  102  configured to hold the liquid supply source  101  serving as a liquid supply source to the liquid ejecting portion  41 . It is sufficient that the liquid supply source  101  is configured to contain a liquid, and therefore the liquid supply source  101  may be, for example, a replaceable cartridge type, or a tank type able to replenish the liquid. The liquid supply source  101  is so provided as to correspond to the number of liquid types used by the liquid ejecting apparatus  10 . 
     The liquid supply flow path  110  of the present embodiment includes a first liquid flow path  111  and a second liquid flow path  112 . The first liquid flow path  111  couples the liquid supply source  101  and the liquid reservoir unit  120 . The second liquid flow path  112  couples the liquid reservoir unit  120  and the liquid ejecting portion  41 . The first liquid flow path  111  and the second liquid flow path  112  are coupled to the connection body  123  of the liquid reservoir unit  120 . 
     It is sufficient for the liquid supply flow path  110  to be a flow path that allows a liquid to flow therethrough. The liquid supply flow path  110  may be formed of, for example, an elastically deformable tube, or may be formed of a flow-path forming member made of a hard resin material. The liquid supply flow path  110  may be formed by pasting a film member on a flow-path forming member in which a groove is formed. 
     The liquid supply device  100  may include a pressurization mechanism  170  configured to pressurize a liquid toward the liquid ejecting portion  41 . The pressurization mechanism  170  is disposed in the liquid supply flow path  110 . The pressurization mechanism  170  is located between the liquid supply source  101  and the liquid reservoir unit  120  in the liquid supply flow path  110 . Therefore, the pressurization mechanism  170  of the present embodiment is disposed in the first liquid flow path  111 . The liquid in the liquid supply source  101  is supplied to the liquid ejecting portion  41  via the liquid reservoir unit  120  by the pressurization mechanism  170 . 
     The pressurization mechanism  170  of the present embodiment includes a volume pump  171 , a first valve  172 , and a second valve  173 . The first valve  172  is located upstream of the volume pump  171  in the liquid supply flow path  110 . The second valve  173  is located downstream of the volume pump  171  in the liquid supply flow path  110 . The first valve  172  and the second valve  173  of the present embodiment are one-way valves that allow the liquid to flow from the upstream toward the downstream in the liquid supply flow path  110 , and restrict a liquid flow from the downstream toward the upstream. Similarly to the on-off valve  140 , the first valve  172  and the second valve  173  may be configured to open and close the liquid supply flow path  110 . 
     The volume pump  171  is configured to apply pressure to a liquid by reciprocating a flexible film  174  having flexibility. The volume pump  171  includes a pump chamber  175  and a negative pressure chamber  176  that are separated by the flexible film  174 . The volume pump  171  includes a depressurization portion  177  for depressurizing the negative pressure chamber  176 , and a pressing member  178  for pressing the flexible film  174  toward the pump chamber  175  side. The pressing member  178  is disposed in the negative pressure chamber  176 . 
     When the depressurization portion  177  depressurizes the negative pressure chamber  176 , the flexible film  174  is displaced so that the volume of the pump chamber  175  becomes larger. At this time, the liquid is drawn from the liquid supply source  101  into the pump chamber  175 . When the depressurizing of the negative pressure chamber  176  by the depressurization portion  177  is stopped, the flexible film  174  is pressed by the pressing member  178 , whereby the flexible film  174  is displaced so that the volume of the pump chamber  175  is reduced. At this time, the liquid is pushed out from the pump chamber  175 . That is, the volume pump  171  of the present embodiment is constituted by a diaphragm pump. The volume pump  171  may be configured by a tube pump. 
     The pressurization mechanism  170  pressurizes the liquid by the pressing member  178  pressing the liquid in the pump chamber  175  via the flexible film  174 . With this, the pressurization mechanism  170  supplies the liquid toward the liquid ejecting portion  41 . A pressurizing force of the pressurization mechanism  170  for pressurizing the liquid is set by a pressing force of the pressing member  178 . 
     The liquid supply device  100  may be configured to supply the liquid from the liquid supply source  101  to the liquid ejecting portion  41  by utilizing a water head difference. In this case, the pressurization mechanism  170  may not be provided. 
     The liquid supply device  100  may include a first filter portion  210 , a second filter portion  220 , a third filter portion  230 , a static mixer  250 , a liquid reservoir portion  260 , a degassing mechanism  270 , and a hydraulic pressure adjustment mechanism  280 . The first filter portion  210 , the second filter portion  220 , the third filter portion  230 , the static mixer  250 , the liquid reservoir portion  260 , the degassing mechanism  270 , and the hydraulic pressure adjustment mechanism  280  are disposed in the liquid supply flow path  110 , and are located between the liquid reservoir unit  120  and the liquid ejecting portion  41 . In the present embodiment, the first filter portion  210 , the static mixer  250 , the liquid reservoir portion  260 , the degassing mechanism  270 , the second filter portion  220 , the hydraulic pressure adjustment mechanism  280 , and the third filter portion  230  are disposed in that order from the upstream in the second liquid flow path  112 . 
     In the first filter portion  210 , the second filter portion  220 , and the third filter portion  230 , the collected foreign objects increase as the operating time increases. For this reason, the liquid ejecting apparatus  10  may be configured such that at least one of the first filter portion  210 , the second filter portion  220 , and the third filter portion  230  is replaceable. For example, as illustrated in  FIG. 2 , the first filter portion  210  may be provided at a position exposed from the housing  12  when a cover  18  of the housing  12  is opened. 
     As illustrated in  FIG. 3 , the first filter portion  210  includes a first filter  211  for collecting foreign objects, a first upstream filter chamber  212  positioned upstream of the first filter  211 , and a first downstream filter chamber  213  positioned downstream of the first filter  211 . The first upstream filter chamber  212  is positioned on a lower side relative to the first downstream filter chamber  213 . The first upstream filter chamber  212  is provided being formed in a substantially conical shape or a substantially truncated conical shape. The first filter  211  is formed in a substantially disk shape to form a bottom surface of the first upstream filter chamber  212 . The height of the first upstream filter chamber  212  may be smaller than the diameter of the first filter  211 . 
     The second filter portion  220  includes a second filter  221  for collecting foreign objects, a second upstream filter chamber  222  positioned upstream of the second filter  221 , and a second downstream filter chamber  223  positioned downstream of the second filter  221 . 
     The third filter portion  230  includes a third filter  231  for collecting foreign objects, a third upstream filter chamber  232  positioned upstream of the third filter  231 , and a third downstream filter chamber  233  positioned downstream of the third filter  231 . 
     The first filter  211 , the second filter  221 , and the third filter  231  may be formed such that a filtration area through which the liquid can pass is larger than a flow path cross-section area of the liquid supply flow path  110 . As the first filter  211 , the second filter  221  and the third filter  231 , for example, a mesh-formed member, a porous member, a perforated plate having fine through-holes formed therein, and the like may be used. As the first filter  211 , the second filter  221  and the third filter  231 , filters of different types and different shapes may be used. 
     Examples of the filter of the mesh-formed member include a wire mesh, a resin mesh, a mesh filter, and a metal fiber. Examples of the filter of the metal fiber include a felt filter in which thin stainless steel wires are processed to be in a felt form, and a metal-sintered filter in which thin stainless steel wires are compressed and sintered. Examples of the perforated plate filter include an electroforming metal filter, an electron beam-processed metal filter, and a laser beam-processed metal filter. 
     The static mixer  250  has a plurality of configurations for dividing the flow of a liquid in a direction in which the liquid flows. The static mixer  250  is configured to divide, change, or reverse the flow of the liquid in the static mixer  250 , thereby reducing unevenness of the concentration in the liquid. 
     The liquid reservoir portion  260  includes a pressurization chamber  261  for storing a liquid, an elastic film  262  forming part of a wall surface of the pressurization chamber  261 , and a first pressing member  263  for pressing the elastic film  262  in a direction in which the volume of the pressurization chamber  261  is reduced. The liquid stored in the pressurization chamber  261  is pressurized by the first pressing member  263 . 
     The liquid reservoir portion  260  pressurizes the liquid stored in the pressurization chamber  261  at a pressure lower than a pressure at which the liquid is pressurized by the pressurization mechanism  170  when the liquid is supplied to the liquid ejecting portion  41 . The pressure at which the liquid is pressurized by the pressurization mechanism  170  when the liquid is supplied to the liquid ejecting portion  41  is, for example, 30 kPa. Accordingly, the liquid reservoir portion  260  pressurizes the liquid stored in the pressurization chamber  261  at a pressure of, for example, 10 kPa. Specifically, the pressure applied to the liquid stored in the pressurization chamber  261  by the elastic film  262  being pressed by the first pressing member  263  is lower than the pressure applied by the pressurization mechanism  170  to supply the liquid from the liquid supply source  101  toward the liquid ejecting portion  41 . Because of this, when the pressure for supplying the liquid from the liquid supply source  101  is not lowered until the arrival at the liquid reservoir portion  260 , the elastic film  262  is displaced in a direction in which the volume of the pressurization chamber  261  is increased against the pressing force of the first pressing member  263 . 
     The degassing mechanism  270  includes a degassing chamber  271  for temporarily storing a liquid, an exhaust chamber  273  separated from the degassing chamber  271  by a degassing film  272 , and an exhaust path  274  for allowing the exhaust chamber  273  to communicate with the exterior. 
     The degassing film  272  has a property of allowing a gas to pass therethrough but not allowing a liquid to pass therethrough. As the degassing film  272 , for example, a film produced in such a manner may be employed that a large number of fine pores of about 0.2 μm are formed in a film prepared by subjecting polytetrafluoroethylene to a special stretching process. When a liquid containing a gas flows into the degassing chamber  271 , only the gas passes through the degassing film  272  and enters into the exhaust chamber  273 . The gas having entered the exhaust chamber  273  is discharged to the exterior through the exhaust path  274 . Thus, bubbles and dissolved gases that are mixed in the liquid stored in the degassing chamber  271  are removed. 
     In the degassing mechanism  270 , the exhaust chamber  273  may be positioned above the degassing chamber  271 . Bubbles and dissolved gases mixed in a liquid are likely to float in the liquid. Therefore, when the exhaust chamber  273  is positioned above the degassing chamber  271 , the bubbles and dissolved gases mixed in the liquid are likely to be removed. 
     The degassing mechanism  270  may include a depressurization pump  275  for depressurizing the exhaust chamber  273 . The depressurization pump  275  depressurizes the exhaust chamber  273  through the exhaust path  274  to remove the bubbles and dissolved gases that are mixed in the liquid stored in the degassing chamber  271 . For example, when it is possible to make the pressure in the exhaust chamber  273  lower than the pressure in the degassing chamber  271  by using a member such as a spring, the depressurization pump  275  may not be provided. In this embodiment, the pressurization of the pressurization mechanism  170  causes the pressure in the degassing chamber  271  to be higher than the pressure in the exhaust chamber  273 . 
     The hydraulic pressure adjustment mechanism  280  of the present embodiment is provided integrally with the second filter portion  220  at a position downstream of the second filter portion  220 . The hydraulic pressure adjustment mechanism  280  includes a liquid chamber  282  communicating with the second downstream filter chamber  223  through a communication hole  281 , and a valve body  283  enable to open and close the communication hole  281 . The hydraulic pressure adjustment mechanism  280  includes a pressure receiving member  284  whose base end side is accommodated in the second downstream filter chamber  223  and whose leading end side is accommodated in the liquid chamber  282 . 
     The liquid chamber  282  of the hydraulic pressure adjustment mechanism  280  is able to store a liquid. Part of a wall surface of the liquid chamber  282  is formed by a flexible wall  285  that can be deflected and displaced. The valve body  283  may be an elastic body such as rubber or resin attached to the base end portion of the pressure receiving member  284  located in the second downstream filter chamber  223 . 
     The hydraulic pressure adjustment mechanism  280  includes a second pressing member  286  accommodated in the second downstream filter chamber  223 , and a third pressing member  287  accommodated in the liquid chamber  282 . The second pressing member  286  presses the valve body  283  in a direction in which the communication hole  281  is closed via the pressure receiving member  284 . The third pressing member  287  pushes back the pressure receiving member  284  when the flexible wall  285  pushes the pressure receiving member  284  by the flexible wall  285  being deflected and displaced in a direction in which the volume of the liquid chamber  282  is reduced. 
     Due to a drop in the internal pressure of the liquid chamber  282 , when the force of the flexible wall  285  pushing the pressure receiving member  284  exceeds the pressing force of the second pressing member  286  and the third pressing member  287 , the valve body  283  opens the communication hole  281 . When the liquid flows into the liquid chamber  282  from the second downstream filter chamber  223  by the communication hole  281  being opened, the internal pressure of the liquid chamber  282  rises. As a result, before the internal pressure of the liquid chamber  282  rises up to a positive pressure, the valve body  283  closes the communication hole  281  by the pressing force of the second pressing member  286  and the third pressing member  287 . In this manner, the internal pressure of the liquid chamber  282  is maintained within a negative pressure range corresponding to the pressing force of the second pressing member  286  and the third pressing member  287 . 
     The internal pressure of the liquid chamber  282  drops along with the discharge of the liquid from the liquid ejecting portion  41 . The valve body  283  autonomously opens and closes the communication hole  281  in accordance with a difference in pressure between the atmospheric pressure, which is an external pressure of the liquid chamber  282 , and the internal pressure of the liquid chamber  282 . Therefore, the hydraulic pressure adjustment mechanism  280  is a differential pressure regulating valve. The differential pressure regulating valve is also referred to as a pressure reducing valve or a self-sealing valve. 
     A valve opening mechanism  290  configured to forcibly open the communication hole  281  to supply the liquid to the liquid ejecting portion  41  may be added to the hydraulic pressure adjustment mechanism  280 . For example, the valve opening mechanism  290  includes a pressurization bag  292  accommodated in an accommodation chamber  291  separated from the liquid chamber  282  by the flexible wall  285 , and a pressurization flow path  293  for allowing a gas to flow into the pressurization bag  292 . 
     The pressurization bag  292  is expanded by the gas flowing thereinto through the pressurization flow path  293 , and the flexible wall  285  is caused to be deflected and displaced in a direction in which the volume of the liquid chamber  282  is reduced, whereby the valve opening mechanism  290  forcibly opens the communication hole  281 . The liquid supply device  100  can perform pressure cleaning in which a liquid is flowed out from the liquid ejecting portion  41 , by pressurizing and supplying the liquid from the liquid supply source  101  to the liquid ejecting portion  41  in a state in which the communication hole  281  is opened. 
     When the liquid supply device  100  is provided with the depressurization pump  275 , the depressurization pump  275  may be shared by the valve opening mechanism  290  and the degassing mechanism  270 . For example, the pressurization flow path  293  may be coupled to the exhaust path  274 , and the depressurization pump  275  may be configured to perform both pressurization driving and depressurization driving. In this case, a check valve  187  may be provided in the exhaust path  274 . In such a configuration, the depressurization pump  275  may perform the pressurization driving to send the gas to the pressurization bag  292 , or the depressurization pump  275  may perform the depressurization driving to depressurize the exhaust chamber  273 . 
     Next, the liquid reservoir unit  120  and the pressure mechanism  150  will be described. 
     The liquid reservoir unit  120  is so provided as to correspond to the number of liquid supply sources  101 . In other words, the liquid reservoir unit  120  is so provided as to correspond to the number of liquid types used by the liquid ejecting apparatus  10 . For example, one liquid reservoir unit  120  may be provided corresponding to one liquid supply source  101 , or two liquid reservoir units  120  may be provided corresponding to one liquid supply source  101 . 
     As illustrated in  FIG. 4 , in the present embodiment, a plurality of liquid reservoir units  120  is provided. The holding portion  152  of the pressure mechanism  150  is configured to hold the liquid reservoir unit  120 . The holding portion  152  of the present embodiment is configured to hold the plurality of liquid reservoir units  120 . The holding portion  152  may be configured to hold one liquid reservoir unit  120 . In this case, a plurality of holding portions  152  may be provided so as to correspond to the plurality of liquid reservoir units  120 . 
     The holding portion  152  of the present embodiment includes a case  161  and a cover  162 . The case  161  and the cover  162  are attached to each other so as to constitute the pressure chamber  151 . 
     As illustrated in  FIG. 5 , the holding portion  152  of the present embodiment includes a plurality of pressure chambers  151 . In the holding portion  152 , the plurality of pressure chambers  151  is positioned to be aligned in a vertical direction. In the holding portion  152 , the plurality of pressure chambers  151  may be positioned to be aligned in the width direction or the depth direction of the liquid ejecting apparatus  10 . The holding portion  152  of the present embodiment includes six pressure chambers  151 . Therefore, the holding portion  152  is configured to hold six liquid reservoir units  120 . 
     The plurality of pressure chambers  151  is configured in such a manner that their spaces are connected to each other by a slit  156  provided in the holding portion  152 . Therefore, when the pump  153  depressurizes one pressure chamber  151 , the other pressure chambers  151  are also depressurized. When the pump  153  pressurizes one pressure chamber  151 , the other pressure chambers  151  are also pressurized. 
     The pressure mechanism  150  may include the pump  153  for each of the pressure chambers  151 . In this case, the pressure can be adjusted for each of the pressure chambers  151 . The pressure mechanism  150  pressurizes the interior of the reservoir portion  121  by the pump  153  sending a gas to the pressure chamber  151  of the holding portion  152 , and applies a negative pressure to the interior of the reservoir portion  121  by the pump  153  discharging the gas from the pressure chamber  151  of the holding portion  152 . 
     The inner wall  154  of the holding portion  152  forming the pressure chamber  151  may be so disposed as to be in contact with the reservoir portion  121  having been displaced to have a larger volume. This makes it possible to suppress excessive displacement of the reservoir portion  121 . In other words, it is possible to suppress an excessive inflation of the bag-like member  122 . Accordingly, damage to the reservoir portion  121  due to the excessive displacement may be reduced. 
     As illustrated in  FIG. 6 , the liquid reservoir unit  120  includes an outflow portion  124  configured to cause a liquid to flow out of the reservoir portion  121 , and an inflow portion  125  configured to cause the liquid to flow into the reservoir portion  121 . The outflow portion  124  and the inflow portion  125  may be disposed at a position near a first end  121 A in the reservoir portion  121 . The first end  121 A of the reservoir portion  121  refers to an end portion through which the liquid flows into or flows out of the reservoir portion  121 . 
     The liquid reservoir unit  120  has predetermined lengths as its width, depth, and height in a state of being installed on a place where it is used. In the reservoir portion  121 , an end portion on the opposite side to the first end  121 A is a second end  121 B. The direction from the first end  121 A toward the second end  121 B is a depth direction of the liquid reservoir unit  120 . 
     The outflow portion  124  has an outflow opening  126  opened to the interior of the reservoir portion  121 . The outflow portion  124  has a lead-out opening  127  opened to the outside of the reservoir portion  121 . The inflow portion  125  has an inflow opening  128  opened to the interior of the reservoir portion  121 . The inflow portion  125  has an introduction opening  129  opened to the outside of the reservoir portion  121 . 
     The outflow opening  126  and the lead-out opening  127  communicate with each other in the outflow portion  124 . The outflow portion  124  is provided being formed in, for example, a tubular shape, and extends to pass through the first end  121 A of the reservoir portion  121 . In the outflow portion  124 , the outflow opening  126  is provided at one end, and the lead-out opening  127  is provided at the other end. 
     The inflow opening  128  and the introduction opening  129  communicate with each other in the inflow portion  125 . The inflow portion  125  is provided being formed in, for example, a tubular shape, and extends to pass through the first end  121 A of the reservoir portion  121 . In the inflow portion  125 , the inflow opening  128  is provided at one end, and the introduction opening  129  is provided at the other end. 
     The outflow portion  124  and the inflow portion  125  of the present embodiment are integrally provided as the connection body  123 . The outflow portion  124  and the inflow portion  125  may be provided independently. 
     The outflow opening  126  and the inflow opening  128  are located at different positions in the depth direction from the first end  121 A toward the second end  121 B. With this, the liquid flows in the reservoir portion  121  from the inflow opening  128  toward the outflow opening  126  in the depth direction. In this process, the liquid is stirred in the reservoir portion  121 . As a result, the settling of liquid components in the reservoir portion  121  is suppressed. 
     The inflow opening  128  may be opened facing the second end  121 B. With this, the liquid coming from the inflow portion  125  flows toward the inner wall of the reservoir portion  121  near the second end  121 B. As a result, the liquid in the reservoir portion  121  may be effectively stirred. In the present embodiment, both the inflow opening  128  and the outflow opening  126  are opened facing the second end  121 B. 
     The outflow opening  126  may be opened to a position closer to the first end  121 A than to the second end  121 B. That is, the outflow opening  126  may be opened to a position near the first end  121 A in the depth direction. The inflow opening  128  may be opened to a position closer to the second end  121 B than to the first end  121 A. That is, the inflow opening  128  may be opened to a position near the second end  121 B in the depth direction. With this, the length of the outflow portion  124  in the depth direction is shorter than the length of the inflow portion  125  in the depth direction. In other words, in the depth direction, the length from the lead-out opening  127  to the outflow opening  126  in the outflow portion  124  is shorter than the length from the introduction opening  129  to the inflow opening  128  in the inflow portion  125 . This reduces the amount of the liquid staying in the outflow portion  124 . As a result, the amount of the liquid in which liquid components settle is reduced in the outflow portion  124 . 
     The outflow portion  124  is coupled to part of the liquid supply flow path  110  closer to the liquid ejecting portion  41 . The outflow portion  124  of the present embodiment is coupled to the second liquid flow path  112 , which is closer to the liquid ejecting portion  41  in the liquid supply flow path  110 . The inflow portion  125  is coupled to part of the liquid supply flow path  110  closer to the liquid supply source  101 . The inflow portion  125  of the present embodiment is coupled to the first liquid flow path  111 , which is closer to the liquid supply source  101  in the liquid supply flow path  110 . 
     The holding portion  152  includes a pressure adjustment tube  157  to which the pressure adjustment flow path  155  is coupled. The pressure adjustment tube  157  is configured to communicate with the pressure chamber  151 . In the present embodiment, one pressure adjustment tube  157  is provided in the holding portion  152 . The pressure adjustment tube  157  of the present embodiment is configured to communicate with one pressure chamber  151  located at the uppermost position in the holding portion  152 . The slit  156  is formed by a gap between the case  161  and the cover  162  attached to each other. 
     The case  161  has a first opening  164  and a second opening  165  for exposing the outflow portion  124  and the inflow portion  125  to the exterior. The outflow portion  124  extends from the interior of the holding portion  152  to the outside of the holding portion  152  through the first opening  164 . Through the second opening  165 , the inflow portion  125  extends from the interior of the holding portion  152  to the outside of the holding portion  152 . The first opening  164  may be provided in the cover  162 . The second opening  165  may be provided in the cover  162 . 
     The holding portion  152  includes a sealing member  163 . The sealing member  163  seals the pressure chamber  151  in which the liquid reservoir unit  120  is accommodated. The sealing member  163  of the present embodiment seals gaps between the outflow portion  124  and inflow portion  125 , and the first opening  164  and second opening  165 . As a result, the pressure chamber  151  becomes a sealed space. 
     The reservoir portion  121  constituted by the bag-like member  122  may be formed by bonding flexible sheets. An edge portion of the reservoir portion  121  is referred to as a bonding portion  130  where flexible sheets are bonded to each other. The bonding portion  130  may be bonded by an adhesive agent, or may be welded by heat or solvent. The connection body  123  is positioned in such a manner as to be pinched by the bonding portion  130 , and is bonded to the bonding portion  130 . 
     As illustrated in  FIG. 7  and  FIG. 8 , the reservoir portion  121  is inflated or deflated by two opposing walls being separated from each other or approaching each other. In the reservoir portion  121 , the two opposing walls are referred to as a first wall  131  and a second wall  132 , respectively. 
     The reservoir portion  121  is displaced between an expansion state in which it is inflated and a flat state in which it is deflated, in accordance with the amount of the liquid stored therein. For example, the reservoir portion  121  is in the expansion state when the amount of the stored liquid is at its maximum, or in the flat state when the amount of the stored liquid is 0. In the expansion state, the first wall  131  and the second wall  132  are separated from each other. In the flat state, the first wall  131  and the second wall  132  approach each other. In the flat state, the reservoir portion  121  is formed in a flat shape. 
     The outflow opening  126  and the inflow opening  128  are located at different positions in the width direction, which is a lengthwise direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A. In the present embodiment, the outflow opening  126  and the inflow opening  128  are located to be aligned in the width direction. In the present embodiment, the lengthwise direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A, coincides with a direction in which the first wall  131  and the second wall  132  extend in the flat state. 
     The holding portion  152  may hold the liquid reservoir unit  120  in such a manner that the height direction, which is a short-length direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A, is taken as a vertical direction. In the present embodiment, the short-length direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A is a direction in which the first wall  131  and the second wall  132  are displaced. In this case, the liquid reservoir unit  120  is disposed such that the reservoir portion  121  becomes flat on a plane along the X-axis and the Y-axis. In other words, the liquid reservoir unit  120  of the present embodiment is arranged in a horizontally placed state. 
     The holding portion  152  of the present embodiment holds the liquid reservoir unit  120  in a horizontally placed state. The holding portion  152  may hold the liquid reservoir unit  120  in a vertically placed state in which the reservoir portion  121  becomes flat on a plane along the Y-axis and the Z-axis. The holding portion  152  may hold the liquid reservoir unit  120  in a vertically placed state in which the reservoir portion  121  becomes flat on a plane along the Z-axis and the X axis. The holding portion  152  may hold the liquid reservoir unit  120  in a posture in which the first end  121 A of the reservoir portion  121  comes to be a lower end of the reservoir portion  121 . The holding portion  152  may hold the liquid reservoir unit  120  in a posture in which the second end  121 B of the reservoir portion  121  comes to be the lower end of the reservoir portion  121 . 
     The reservoir portion  121  is configured such that the size thereof in the direction in which the first wall  131  and the second wall  132  extend in the flat state is larger than the size thereof in the direction in which the first wall  131  and the second wall  132  are displaced. 
     Next, an example of a maintenance method for maintenance of the liquid ejecting apparatus  10  will be described. 
     When a liquid stays in the reservoir portion  121 , components of the liquid settle. At this time, when the liquid in which the components thereof have settled is used for printing, color unevenness, uneven drying, and the like are caused by unevenness of the concentration, which affects the print quality. Therefore, as a maintenance method for the liquid ejecting apparatus  10 , the control portion  60  controls the discharge mechanism  50  to discharge the liquid stored in the reservoir portion  121  as a waste liquid when a stay of the liquid in the reservoir portion  121  exceeds a set time. 
     The set time is a period of time, after the passage of which the print quality may be affected by the settling of the liquid components. The control portion  60  counts the time since when the liquid was stored in the reservoir portion  121 . When the stay of the liquid in the reservoir portion  121  exceeds the set time, the control portion  60  performs, for example, suction cleaning to discharge the liquid stored in the reservoir portion  121  as a waste liquid. 
     When print data is input, the control portion  60  of the present embodiment performs a printing process to print an image based on the print data. In the printing process, the control portion  60  refers to a time for which the liquid has stayed in the reservoir portion  121 . 
     As illustrated in  FIG. 9 , in step S 11 , the control portion  60  in charge of performing the printing process determines whether or not a staying time Tx is smaller than a cumulative staying time Ty. Each of the staying time Tx and the cumulative staying time Ty indicate the time for which the liquid has stayed in the reservoir portion  121 . 
     The control portion  60  counts the elapsed time as the staying time Tx while the liquid ejecting apparatus  10  is electrically conductive regardless of whether the power supply is turned on or off. Therefore, the value of the staying time Tx increases as time passes. The staying time Tx is reset by supplying the liquid stored in the reservoir portion  121  to the liquid ejecting portion  41 . 
     The cumulative staying time Ty is a parameter for storing the value of the staying time Tx. When a value of the staying time Tx is stored as the cumulative staying time Ty, the control portion  60  starts to count the cumulative staying time Ty. Accordingly, the cumulative staying time Ty takes a value obtained by adding the stored staying time Tx to the time having passes since the staying time Tx was stored. The cumulative staying time Ty is reset at a predetermined timing. 
     In step S 11 , when the staying time Tx is smaller than the cumulative staying time Ty, the control portion  60  shifts the process to step S 12 . In step S 11 , when the staying time Tx is equal to or greater than the cumulative staying time Ty, the control portion  60  shifts the process to step S 14 . 
     In step S 12 , the control portion  60  sets the value of the cumulative staying time Ty to the staying time Tx. At this time, the staying time Tx and the cumulative staying time Ty have the same value. 
     In step S 13 , the control portion  60  resets the cumulative staying time Ty. At this time, the cumulative staying time Ty has a value of 0, and the counting of the cumulative staying time Ty is stopped. 
     In step S 14 , the control portion  60  determines whether or not the staying time Tx exceeds a first set time T 1 . The first set time T 1  is a time when the settling of the liquid components is estimated to occur in the reservoir portion  121 . Therefore, when the staying time Tx is equal to or less than the first set time T 1 , it is expected that the settling of the liquid components has not occurred yet in the reservoir portion  121 . In the present embodiment, the first set time T 1  is, for example, one month. 
     In step S 14 , when the staying time Tx exceeds the first set time T 1 , the control portion  60  shifts the process to step S 15 . In step S 14 , when the staying time Tx is equal to or less than the first set time T 1 , the control portion  60  shifts the process to step S 23 . 
     In step S 23 , the control portion  60  performs printing using the liquid contained in the liquid supply source  101 . At this time, the control portion  60  supplies the liquid toward the liquid ejecting portion  41  from the liquid supply source  101  so that the volume of the liquid stored in the reservoir portion  121  does not change. When processing in step S 23  is finished, the control portion  60  ends the printing process. 
     When the staying time Tx exceeds the first set time T 1  in step S 14 , the control portion  60  determines whether or not the staying time Tx exceeds a second set time T 2  in step S 15 . The second set time T 2  is a time when the settling of the liquid components is estimated to be progressed in the reservoir portion  121 . In the present embodiment, when the staying time Tx is equal to or less than the second set time T 2  and exceeds the first set time T 1 , it is expected that the settling of the liquid components in the reservoir portion  121  is a small amount. When the staying time Tx exceeds the second set time T 2 , it is expected that the settling of the liquid components in the reservoir portion  121  is a large amount. In the present embodiment, the second set time T 2  is, for example, six months. 
     In step S 15 , when the staying time Tx exceeds the second set time T 2 , that is, when it is expected that the settling of the liquid components in the reservoir portion  121  is a large amount, the control portion  60  shifts the process to step S 21 . In step S 15 , when the staying time Tx is equal to or less than the second set time T 2 , that is, when it is expected that the settling of the liquid components in the reservoir portion  121  is a small amount, the control portion  60  shifts the process to step S 16 . 
     In step S 16 , the control portion  60  performs printing using the liquid stored in the reservoir portion  121 . At this time, the control portion  60  supplies the liquid toward the liquid ejecting portion  41  from the reservoir portion  121  so that the volume of the liquid stored in the reservoir portion  121  becomes small. In step S 16 , since the settling of the liquid components in the reservoir portion  121  is expected to be a small amount, the liquid in the reservoir portion  121  is stirred by supplying the liquid from the reservoir portion  121  toward the liquid ejecting portion  41 . When the liquid in the reservoir portion  121  is sufficiently stirred, the settling of the liquid components in the reservoir portion  121  is resolved. 
     In step S 16 , the control portion  60  counts the amount of the liquid supplied to the liquid ejecting portion  41  from the reservoir portion  121 . After having finished the printing, the control portion  60  supplies the liquid to the reservoir portion  121  from the liquid supply source  101 . Thus, an old liquid is replaced with a new liquid in the reservoir portion  121 . 
     In step S 17 , the control portion  60  determines whether or not a liquid consumption amount Wx is equal to or greater than a set consumption amount W 1 . The liquid consumption amount Wx indicates the amount of the liquid in the reservoir portion  121  which was consumed in the printing. That is, the liquid consumption amount Wx includes the amount of the liquid having been supplied from the reservoir portion  121  to the liquid ejecting portion  41  in step S 16 . The set consumption amount W 1  is a liquid consumption amount which is expected to be able to resolve the settling of the liquid components, when the settling of the liquid components in the reservoir portion  121  is a small amount. In the present embodiment, the setting consumption amount W 1  is, for example, five grams. 
     As the amount of the liquid supplied from the reservoir portion  121  to the liquid ejecting portion  41  increases, the liquid is further stirred in the reservoir portion  121 . In the present embodiment, when the liquid consumption amount Wx is equal to or greater than the set consumption amount W 1 , it is expected that the settling of the liquid components in the reservoir portion  121  has been resolved. When the liquid consumption amount Wx is less than the set consumption amount W 1 , it is expected that the settling of the liquid components in the reservoir portion  121  has not been resolved. 
     In step S 17 , when the liquid consumption amount Wx is equal to or greater than the set consumption amount W 1 , that is, when it is expected that the settling of the liquid components in the reservoir portion  121  has been resolved, the control portion  60  shifts the process to step S 18 . When the liquid consumption amount Wx is less than the set consumption amount W 1  in step S 17 , that is, when it is expected that the settling of the liquid components in the reservoir portion  121  has not been resolved, the control portion  60  shifts the process to step S 20 . 
     In step S 18 , the control portion  60  resets the liquid consumption amount Wx. At this time, the liquid consumption amount Wx becomes 0. 
     In step S 19 , the control portion  60  resets the staying time Tx. At this time, the value of the staying time Tx becomes 0. The counting of the staying time Tx is continued after being reset. After having completed processing in step S 19 , the control portion  60  ends the printing process. 
     When the liquid consumption amount Wx is less than the set consumption amount W 1  in step S 17 , the control portion  60  sets the value of the staying time Tx to the cumulative staying time Ty in step S 20 . At this time, the staying time Tx and the cumulative staying time Ty have the same value. After the value of the staying time Tx is set, the counting of the cumulative staying time Ty is started. The control portion  60 , after having completed processing in step S 20 , resets the staying time Tx in step S 19 . 
     When the staying time Tx exceeds the second set time T 2  in step S 15 , the control portion  60  discharges the liquid in the reservoir portion  121  in step S 21 . When the staying time Tx exceeds the second set time T 2 , the control portion  60  discharges the liquid in the reservoir portion  121  because the settling of the liquid components in the reservoir portion  121  has progressed. In the present embodiment, the control portion  60  performs suction cleaning in step S 21 . The control portion  60 , after having discharged the liquid in the reservoir portion  121 , supplies a liquid to the reservoir portion  121  from the liquid supply source  101 . Thus, the old liquid is replaced with a new liquid in the reservoir portion  121 . 
     In step S 22 , the control portion  60  resets the liquid consumption amount Wx and the staying time Tx. At this time, the values of the liquid consumption amount Wx and the staying time Tx become 0. The counting of the staying time Tx is continued after being reset. 
     The control portion  60 , after having completed processing in step S 22 , performs printing using the liquid in the liquid supply source  101  in step S 23 . After having completed processing in step S 23 , the control portion  60  ends the printing process. 
     By storing the staying time Tx as the cumulative staying time Ty in the current printing process, it is possible to determine whether or not the settling of the liquid components in the reservoir portion  121  will be resolved in the next printing process. When the value of the staying time Tx is set to the cumulative staying time Ty in step S 20  of the current printing process, the staying time Tx becomes equal to or less than the cumulative staying time Ty in step S 11  of the next printing process. Accordingly, in this case, in step S 12  of the next printing process, the value of the cumulative staying time Ty is set to the staying time Tx. In this manner, the staying time Tx in the current printing process is handed over to the next printing process. 
     In the printing process, when the processing in step S 20  is selected and carried out, the liquid consumption amount Wx is not reset. Therefore, when the liquid consumption amount Wx is less than the set consumption amount W 1  in the current printing process, the liquid consumption amount Wx in the current printing process is handed over to the next printing process. 
     In the next printing process, operations are performed based on the value of the handed-over staying time Tx and the value of the handed-over liquid consumption amount Wx. In the next printing process, when a time obtained by adding the handed-over staying time Tx to the time counted after being handed over is less than the second set time T 2  and an amount obtained by adding the handed-over liquid consumption amount Wx to the amount of liquid consumption after being handed over is equal to or greater than the set consumption amount W 1 , it is expected that the settling of the liquid components in the reservoir portion  121  will be resolved. That is, when a liquid in an amount equal to or greater than the set consumption amount W 1  is supplied from the reservoir portion  121  toward the liquid ejecting portion  41  before the time having passed since the reservoir portion  121  stored the liquid exceeds the second set time T 2 , the settling of the liquid components in the reservoir portion  121  will be resolved. 
     Next, operations and effects of the above embodiment will be described. 
     1. The outflow opening  126  and the inflow opening  128  are located at different positions in the width direction which is a lengthwise direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A, and also located at different positions in the depth direction from the first end  121 A toward the second end  121 B on the opposite side to the first end  121 A. In the liquid reservoir unit  120 , the liquid flows into the reservoir portion  121  through the inflow opening  128  of the inflow portion  125 . The liquid flows out of the reservoir portion  121  through the outflow opening  126  of the outflow portion  124 . Therefore, in the reservoir portion  121 , the liquid flows from the inflow opening  128  toward the outflow opening  126 ; note that the inflow opening  128  and the outflow opening  126  are located at the different positions in the width direction and the depth direction. At this time, the liquid is stirred in the reservoir portion  121 . This makes it possible to suppress the settling of the liquid components. 
     2. The inflow opening  128  is opened facing the second end  121 B. With this, the liquid flowing into the reservoir portion  121  flows from the inflow opening  128  toward the inner wall near the second end  121 B. As a result, the liquid is effectively stirred in the reservoir portion  121 . 
     3. The outflow opening  126  is opened to a position closer to the first end  121 A than to the second end  121 B, and the inflow opening  128  is opened to a position closer to the second end  121 B than to the first end  121 A. With this, since the length of the outflow portion  124  in the depth direction can be shortened, the amount of the liquid staying in the outflow portion  124  can be reduced. As a result, the amount of the liquid in which the components have settled can be reduced in the outflow portion  124 . 
     4. The reservoir portion  121  is constituted of the bag-like member  122  having flexibility. By doing so, it is possible to cause the liquid to flow inside the reservoir portion  121  by deforming the reservoir portion  121  constituted of the bag-like member  122 . This makes it possible to suppress the settling of the liquid components. 
     5. The liquid ejecting apparatus  10  includes the control portion  60  configured to control the discharge mechanism  50  to discharge the liquid staying in the reservoir portion  121  as a waste liquid when a stay of the liquid in the reservoir portion  121  exceeds the set time. According to the liquid ejecting apparatus  10 , the liquid whose components are expected to have settled in the reservoir portion  121  can be discharged as a waste liquid. Thus, for example, it is possible to reduce a risk of printing an image on the medium M by using the liquid in which the components have settled. 
     6. The outflow portion  124  is coupled to part of the liquid supply flow path  110  closer to the liquid ejecting portion  41 , and the inflow portion  125  is coupled to part of the liquid supply flow path  110  closer to the liquid supply source  101 . In this case, the liquid flows from the liquid supply source  101  toward the liquid ejecting portion  41 , whereby the liquid stored in the reservoir portion  121  is stirred. This makes it possible to suppress the settling of the liquid components. 
     7. The holding portion  152  holds the liquid reservoir portion  121  in such a manner that the height direction, which is a short-length direction of the reservoir portion  121  when the reservoir portion  121  is viewed from the first end  121 A, is taken as a vertical direction. This makes it possible for the holding portion  152  to hold the liquid reservoir unit  120  in a horizontally placed state. 
     The present embodiment may be modified and implemented as follows. The present embodiment and the following modifications may be implemented in combination with each other within a range where no technical contradiction exists. 
     As illustrated in  FIG. 10 , the liquid reservoir unit  120  may be configured such that part of the wall of the reservoir portion  121  is formed of a flexible member  133 . In this case, for example, the pressure mechanism  150  depressurizes or pressurizes a space around the reservoir portion  121 , thereby displacing the flexible member  133 . Thus, the amount of liquid stored in the reservoir portion  121  may be controlled. Further, as illustrated in  FIG. 10 , the holding portion  152  may hold the liquid reservoir unit  120  in a posture in which the flexible member  133  forms an upper wall of the liquid reservoir unit  120 , or may hold the liquid reservoir unit  120  in a posture in which the flexible member  133  forms a lower wall of the liquid reservoir unit  120 . 
     As illustrated in  FIG. 11 , the reservoir portion  121  may be configured as a rigid case, for example. A region where a liquid is present and a region where a gas is present appear in the reservoir portion  121 . In this case, for example, the pressure mechanism  150  depressurizes or pressurizes the upper space where the gas is present in the reservoir portion  121 , thereby making it possible to control the amount of liquid stored in the reservoir portion  121 . 
     The outflow opening  126  may be located closer to an edge of the reservoir portion  121  in the width direction of the reservoir portion  121 . For example, the outflow opening  126  may be provided at a position where a distance between the outflow opening  126  and the bonding portion  130  is smaller than a distance between the outflow opening  126  and the inflow opening  128  in the width direction of the reservoir portion  121 . 
     The inflow opening  128  may be located closer to the edge of the reservoir portion  121  in the width direction of the reservoir portion  121 . For example, the inflow opening  128  may be provided at a position where a distance between the inflow opening  128  and the bonding portion  130  is smaller than the distance between the inflow opening  128  and the outflow opening  126  in the width direction of the reservoir portion  121 . 
     The inflow opening  128  may be opened on a circumferential surface of the tubular inflow portion  125 . A plurality of inflow openings  128  may be opened on the inflow portion  125 . 
     The outflow portion  124  and the inflow portion  125  may be constituted of, for example, a flexible tube. 
     The liquid reservoir unit  120  may be configured to allow a gas to flow thereinto through the inflow portion  125 . In this case, the liquid reservoir unit  120  may be used as the liquid supply source  101 . 
     The liquid ejecting apparatus  10  may be configured to perform choke cleaning in a state in which the pressure chamber  151  is opened to the atmosphere. When the choke cleaning is performed in a state in which the pressure chamber  151  is opened to the atmosphere, bubbles, foreign objects, and the like in the reservoir portion  121  may be discharged. 
     Not only during the maintenance but also during the liquid ejecting apparatus  10  performing printing, the pressure mechanism  150  may apply a negative pressure to the interior of the reservoir portion  121  when the liquid ejecting apparatus  10  is in a standby mode or the like. For example, the pressure mechanism  150  may apply a negative pressure to the interior of the reservoir portion  121  so that the amount of the liquid stored in the reservoir portion  121  is maintained at a level of a predetermined amount or more than a predetermined amount. That is, the pressure mechanism  150  may depressurize the interior of the pressure chamber  151  so that the bag-like member  122  is maintained to be in contact with the inner wall  154  of the holding portion  152 . This makes it possible to supply the liquid from the liquid supply source  101  toward the liquid ejecting portion  41  while maintaining the amount of the liquid stored in the reservoir portion  121  at the level of the predetermined amount or more than the predetermined amount. 
     The liquid reservoir unit  120  may be mounted in the carriage  43 . 
     The medium M may be a metal film, a plastic film, a cloth, or the like. 
     The liquid ejected by the liquid ejecting portion  41  is not limited to ink, and may be, for example, a liquid material obtained by dispersing or mixing particles of a functional material in a liquid. For example, the liquid ejecting portion  41  may eject a liquid material containing a material such as an electrode material or a pixel material used for the manufacture of liquid crystal displays, electroluminescence displays, surface-emitting displays, and the like in the form of dispersion or dissolution. 
     Technical ideas and operational advantages understood from the above embodiment and modifications will be described below. 
     A liquid reservoir unit includes a reservoir portion configured to store a liquid; an outflow portion disposed at a position near a first end of the reservoir portion and configured to cause the liquid to flow out of the reservoir portion; and an inflow portion disposed at a position near the first end of the reservoir portion and configured to cause the liquid to flow into the reservoir portion. The outflow portion includes an outflow opening opened to an interior of the reservoir portion, and the inflow portion includes an inflow opening opened to the interior of the reservoir portion. The outflow opening and the inflow opening are located at different positions in a width direction which is a lengthwise direction of the reservoir portion when the reservoir portion is viewed from the first end, and also located at different positions in a depth direction from the first end toward a second end on the opposite side to the first end. 
     According to this configuration, the liquid flows into the reservoir portion through the inflow opening of the inflow portion. The liquid flows out of the reservoir portion through the outflow opening of the outflow portion. Therefore, in the reservoir portion, the liquid flows from the inflow opening toward the outflow opening; the inflow opening and the outflow opening are located at different positions in the width direction and the depth direction. At this time, the liquid is stirred in the reservoir portion. This makes it possible to suppress the settling of the liquid components. 
     The inflow opening may be opened facing the second end in the liquid reservoir unit. 
     With this configuration, the liquid flowing into the reservoir portion flows from the inflow opening toward the inner wall near the second end. As a result, the liquid is effectively stirred in the reservoir portion. 
     In the liquid reservoir unit, the outflow opening may be opened to a position closer to the first end than to the second end, and the inflow opening may be opened to a position closer to the second end than to the first end. 
     With this configuration, since the length of the outflow portion in the depth direction can be shortened, the amount of the liquid staying in the outflow portion can be reduced. As a result, the amount of the liquid in which the components have settled may be reduced in the outflow portion. 
     In the liquid reservoir unit, the reservoir portion may be constituted of a flexible bag-like member. 
     According to this constitution, it is possible to cause the liquid to flow inside the reservoir portion by deforming the reservoir portion constituted of the bag-like member. This makes it possible to suppress the settling of the liquid components. 
     A liquid ejecting apparatus includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; a liquid reservoir unit having a reservoir portion that is provided in the liquid supply flow path and is configure to store the liquid; a discharge mechanism configured to discharge the liquid in the liquid supply flow path from a side of the liquid ejecting portion relative to the reservoir portion in the liquid supply flow path by depressurizing the liquid supply flow path; and a control portion configured to control the discharge mechanism to discharge the liquid staying in the reservoir portion as a waste liquid when a stay of the liquid in the reservoir portion exceeds a set time. 
     According to this configuration, the liquid whose components are expected to have settled in the reservoir portion can be discharged as a waste liquid. Thus, for example, it is possible to reduce a risk of printing an image on a medium by using the liquid in which the components have settled. 
     In the liquid ejecting apparatus, the liquid reservoir unit may include a bag-like member constituting the reservoir portion, an outflow portion disposed at a position near a first end of the reservoir portion and configured to cause the liquid to flow out of the reservoir portion, and an inflow portion disposed at a position near the first end and configured to cause the liquid to flow into the reservoir portion; the outflow portion may be coupled to part of the liquid supply flow path closer to the liquid ejecting portion, and the inflow portion may be coupled to part of the liquid supply flow path closer to the liquid supply source. 
     With this configuration, the liquid flows from the liquid supply source toward the liquid ejecting portion, whereby the liquid stored in the reservoir portion is stirred. This makes it possible to suppress the settling of the liquid components. 
     The liquid ejecting apparatus may include a holding portion for holding the liquid reservoir unit, the outflow portion may have an outflow opening opened to the interior of the reservoir portion, the inflow portion may have an inflow opening opened to the interior of the reservoir portion, the outflow opening and the inflow opening may be located at different positions in the width direction which is a lengthwise direction of the reservoir portion when the reservoir portion is viewed from the first end, and the holding portion may hold the reservoir portion in such a manner that the height direction, which is a short-length direction of the reservoir portion when the reservoir portion is viewed from the first end, is taken as a vertical direction. 
     This configuration makes it possible for the holding portion to hold the liquid reservoir unit in a horizontally placed state. 
     In the liquid ejecting apparatus, the outflow opening and the inflow opening may be located at different positions in the depth direction from the first end toward a second end on the opposite side to the first end. 
     With this configuration, when the liquid flows from the liquid supply source toward the liquid ejecting portion, the liquid stored in the reservoir portion is effectively stirred. This makes it possible to suppress the settling of the liquid components. 
     In the liquid ejecting apparatus, the inflow opening may be opened facing the second end on the opposite side to the first end. 
     With this configuration, when the liquid flows into the reservoir portion, it flows from the inflow opening toward the inner wall near the second end. As a result, the liquid is effectively stirred inside the reservoir portion. 
     In the liquid ejecting apparatus, the outflow opening may be opened to a position closer to the first end than to the second end on the opposite side to the first end, and the inflow opening may be opened to a position closer to the second end than to the first end. 
     With this configuration, since the length of the outflow portion in the depth direction can be shortened, the amount of the liquid staying inside the outflow portion can be reduced. As a result, the amount of the liquid in which the components have settled may be reduced inside the outflow portion. 
     A maintenance method for a liquid ejecting apparatus is a maintenance method for the liquid ejecting apparatus that includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; and a liquid reservoir unit having a reservoir portion provided in the liquid supply flow path and configured to store the liquid. The method includes discharging the liquid staying in the reservoir portion as a waste liquid when a stay of the liquid in the reservoir portion exceeds a set time. 
     According to this method, the liquid whose components are expected to have settled in the reservoir portion can be discharged as a waste liquid. Thus, for example, it is possible to reduce a risk of printing an image on a medium by using the liquid in which the components have settled. 
     Second Embodiment 
     Next, a second embodiment of a liquid ejecting apparatus and a control method for a liquid ejecting apparatus will be described with reference to the accompanying drawings. The second embodiment is different from the first embodiment in the configuration of a liquid supply source and the control of a liquid ejecting apparatus. Since other points are substantially the same as those of the first embodiment, the same reference numerals are given to the same constituent elements so as to omit redundant description thereof. 
     As illustrated in  FIG. 12 , a pressure mechanism  150  as a reservoir amount adjustment mechanism is configured to adjust a reservoir amount SA of a liquid stored in a reservoir portion  121 . The pressure mechanism  150  may apply pressure to the interior of the reservoir portion  121  from the exterior. The pressure mechanism  150  may apply pressure to the interior of the reservoir portion  121  via the flexible member  133 . 
     The pressure mechanism  150  of the present embodiment applies a positive pressure, by pressurizing the outside of the reservoir portion  121 , to the liquid in the reservoir portion  121  to deflate a bag-like member  122  in such a manner as to decrease the volume of the reservoir portion  121 . The pressure mechanism  150  inflates the bag-like member  122  in such a manner as to increase the volume of the reservoir portion  121  by depressurizing the outside of the reservoir portion  121 . When the bag-like member  122  is inflated, the pressure inside the reservoir portion  121  is reduced. In this manner, the pressure mechanism  150  applies a negative pressure to the interior of the reservoir portion  121  from the outside of the reservoir portion  121 . The pressure mechanism  150  may be configured to apply pressure from the exterior to the interior of the reservoir portion  121  by displacing the flexible member  133  by using a mechanical element such as a spring or a lever. 
     The pressure mechanism  150  may include a holding portion  152  having a pressure chamber  151  for accommodating the reservoir portion  121 , and a pump  153  for pressurizing or depressurizing the interior of the pressure chamber  151 . The pressure mechanism  150  pressurizes the interior of the pressure chamber  151  by using the pump  153 , thereby applying a positive pressure to the interior of the reservoir portion  121  from the exterior. The pressure mechanism  150  depressurizes the interior of the pressure chamber  151  by using the pump  153 , thereby applying a negative pressure to the interior of the reservoir portion  121  from the exterior. When the interior of the pressure chamber  151  is pressurized, the bag-like member  122  is deflated. The deflated bag-like member  122  leaves an inner wall  154  of the holding portion  152  forming the pressure chamber  151 . When the interior of the pressure chamber  151  is depressurized, the bag-like member  122  is inflated. The inflated bag-like member  122  makes contact with the inner wall  154 . 
     The pressure mechanism  150  adjusts the pressure inside the reservoir portion  121  by changing the pressure inside the pressure chamber  151 . The pressure mechanism  150  changes a volume of the interior of the bag-like member  122  by applying pressure to the outside of the bag-like member  122 , thereby adjusting the reservoir amount SA. The pressure mechanism  150  may be configured to open the pressure chamber  151  to the atmosphere. 
     The pressure mechanism  150  may include a pressure adjustment flow path  155  coupling the pressure chamber  151  and the pump  153  located outside the holding portion  152 . The pump  153  pressurizes or depressurizes the pressure chamber  151  through the pressure adjustment flow path  155 . The pump  153  may be located inside the holding portion  152 . 
     Next, a liquid supply device  100  of the present embodiment will be described. 
     The liquid supply device  100  includes a liquid supply source holding portion  102  configured to attach and detach a liquid supply source  101  containing a liquid. A liquid supply flow path  110  is configured to supply a liquid, to the liquid ejecting portion  41 , from the liquid supply source  101  mounted on the liquid supply source holding portion  102 . 
     It is sufficient that the liquid supply source  101  is configured to contain a liquid, and therefore the liquid supply source  101  may be, for example, a replaceable cartridge type, or a tank type able to replenish the liquid. The liquid supply source  101  is so provided as to correspond to the number of liquid types used by the liquid ejecting apparatus  10 . 
     The liquid supply device  100  may include a remaining amount acquisition portion  103  configured to acquire a remaining amount Ra of the liquid contained in the liquid supply source  101 . The remaining amount acquisition portion  103  may detect the liquid contained in the liquid supply source  101  by using an optical sensor. The remaining amount acquisition portion  103  of the present embodiment includes a light emitting portion  105  configured to emit light toward a prism  104  included in the liquid supply source  101 , and a light receiving portion  106  configured to receive light that returns from the prism  104 . The prism  104  is, for example, a triangular prism. The traveling direction of the light incident on the prism  104  is changed in accordance with the amount of liquid contained in the liquid supply source  101 . 
     Specifically, when the liquid is sufficiently contained in the liquid supply source  101 , a contact area between the prism  104  and the liquid is large. As such, the light incident on the prism  104  travels in the liquid in such a manner as to pass through the prism  104 , and only a small amount of light returns to the light receiving portion  106 . When the amount of liquid contained in the liquid supply source  101  becomes small and the prism  104  is exposed from the liquid, the contact area between the prism  104  and the liquid is small. Because of this, the light incident on the prism  104  is reflected in such a manner as to travel in the prism  104  and then arrives at the light receiving portion  106 . Therefore, the amount of light received by the light receiving portion  106  when the prism  104  is exposed from the liquid, is larger than that of when the prism  104  is hidden in the liquid. 
     The remaining amount acquisition portion  103  outputs the amount of light received by the light receiving portion  106  to the control portion  60 . The control portion  60  determines whether or not the remaining amount Ra of the liquid contained in the liquid supply source  101  is equal to or less than a predetermined value VP, or equal to or less than a limit value VL based on the amount of light received by the light receiving portion  106 . 
     Next, a reservoir unit  120  according to the second embodiment will be described. 
     As illustrated in  FIG. 13 , the reservoir unit  120  may include an outflow portion  124  for leading a liquid out of the reservoir unit  120 , and an inflow portion  125  for introducing a liquid into the reservoir unit  120 . The outflow portion  124  and the inflow portion  125  of the present embodiment are provided in a connection body  123 , and have openings in the bag-like member  122 . The liquid introduced from the inflow portion  125  is led out from the outflow portion  124  through the interior of the reservoir unit  120 . 
     The connection body  123  may have a coupling path  136  for coupling the inflow portion  125  and the outflow portion  124 . With this, even when the bag-like member  122  is completely deflated, the liquid may be allowed to flow from the inflow portion  125  to the outflow portion  124  through the coupling path  136 . 
     Next, an upper limit value of the reservoir amount SA of the liquid stored in the reservoir portion  121 , and the predetermined value VP and the limit value VL of the remaining amount Ra of the liquid contained in the liquid supply source  101  will be described. 
     As illustrated in  FIG. 12  and  FIG. 13 , the reservoir portion  121  stores a liquid in the bag-like member  122  having a variable shape. Therefore, the reservoir amount SA, which is the amount of the liquid stored in the reservoir portion  121 , varies depending on the shape of the bag-like member  122 . 
     As illustrated in  FIG. 12 , for example, the pressure mechanism  150  depressurizes the interior of the pressure chamber  151  to cause the pressure outside the bag-like member  122  to be lower than the pressure inside the bag-like member  122 , thereby inflating the bag-like member  122 . When the bag-like member  122  is inflated up to the maximum, the outer surface of the bag-like member  122  is brought into contact with the inner wall  154 . The reservoir amount SA of the reservoir portion  121  in this state is at its maximum. In this embodiment, the maximum amount of liquid that can be stored in the reservoir portion  121  is defined as a first upper limit value V 1 . 
     As illustrated in  FIG. 14 , for example, the pressure mechanism  150  pressurizes the interior of the pressure chamber  151  to cause the pressure outside the bag-like member  122  to be higher than the pressure inside the bag-like member  122 , thereby deflating the bag-like member  122 . When the bag-like member  122  is deflated, the opposing inner surfaces of the bag-like member  122  are brought into contact with each other. The reservoir amount SA in this state is defined as a second upper limit value V 2 . When the bag-like member  122  is completely deflated, a contact area between the inner surfaces of the bag-like member  122  becomes maximum, and the reservoir amount SA becomes minimum. The second upper limit value V 2  may be the same as the minimum reservoir amount SA, or may be larger than the minimum reservoir amount SA and smaller than the first upper limit value V 1 . 
     As illustrated in  FIG. 14 , the predetermined value VP may be the same as the first upper limit value V 1 , or may be a value larger than the first upper limit value V 1 . The limit value VL is a value smaller than the predetermined value VP, and is, for example, 0 or significantly small. When the remaining amount Ra becomes equal to the limit value VL, the liquid cannot be supplied to a liquid ejecting portion  41  from the liquid supply source  101 . Accordingly, the limit value VL is an amount of liquid indicating that the liquid supply source  101  is required to be replaced. 
     Next, a control method for the liquid ejecting apparatus  10  will be described with reference to a flowchart illustrated in  FIG. 15 . 
     As illustrated in  FIG. 15 , in step S 101 , the control portion  60  drives the pump  153  for pressurization to pressurize the pressure chamber  151 . In step S 102 , the control portion  60  drives a pressurization mechanism  170 . In step S 103 , the control portion  60  determines whether or not the remaining amount Ra of the liquid contained in the liquid supply source  101  is equal to or smaller than the predetermined value VP. 
     When the remaining amount Ra is greater than the predetermined value VP, step S 103  indicates “NO”. The control portion  60  waits until the remaining amount Ra becomes equal to or smaller than the predetermined value VP in a state in which the pressure chamber  151  is pressurized. When the remaining amount Ra becomes equal to or smaller than the predetermined value VP, step S 103  indicates “YES”. In step S 104 , the control portion  60  makes the pressure chamber  151  open to the atmosphere, and releases the pressurized state of the pressure chamber  151 . At this time, the control portion  60  continuously drives the pressurization mechanism  170 . 
     In step S 105 , the control portion  60  determines whether or not the remaining amount Ra is equal to or smaller than the limit value VL. When the remaining amount Ra is greater than the limit value VL, step S 105  indicates “NO”. The control portion  60  continues the driving of the pressurization mechanism  170 , and waits until the remaining amount Ra becomes equal to or smaller than the limit value VL. When the remaining amount Ra becomes equal to or smaller than the limit value VL, step S 105  indicates “YES”. The control portion  60  shifts the process to step S 106 . 
     In step S 106 , the control portion  60  stops the driving of the pressurization mechanism  170 . In step S 107 , the control portion  60  pressurizes the pressure chamber  151  by driving the pump  153  for pressurization. In step S 108 , the control portion  60  displays information on the operation panel  17 , for example, for prompting the replacement of the liquid supply source  101 , and reports that the remaining amount Ra has become equal to the limit value VL. 
     In step S 109 , the control portion  60  determines whether or not the remaining amount Ra is greater than the predetermined value VP. When the remaining amount Ra is equal to or smaller than the predetermined value VP, step S 109  indicates “NO”, and the control portion  60  waits. When the liquid supply source  101  is replaced and the remaining amount Ra becomes larger than the predetermined value VP, step S 109  indicates YES. The control portion  60  shifts the process to step S 102 . The control portion  60  repeatedly performs the above-described liquid supply routine while the power supply of the liquid ejecting apparatus  10  is turned on. 
     Operations of the present embodiment will be described. 
     As illustrated in  FIG. 14 , the control portion  60  controls the pressure mechanism  150  to cause the reservoir amount SA, when the remaining amount Ra is greater than the predetermined value VP, to be smaller than the first upper limit value V 1 . When the remaining amount Ra is greater than the predetermined value VP, the control portion  60  of the present embodiment controls the pressure mechanism  150  to cause the reservoir amount SA to be equal to or smaller than the second upper limit value V 2 , which is smaller than the first upper limit value V 1 . 
     Specifically, when the remaining amount Ra is greater than the predetermined value VP, the control portion  60  drives the pump  153  for pressurization to make the pressure in the pressure chamber  151  higher than the pressure of the liquid inside the reservoir portion  121  pressurized by the pressurization mechanism  170 . That is, in the reservoir portion  121 , when the remaining amount Ra is greater than the predetermined value VP, the opposing inner surfaces of the bag-like member  122  are in contact with each other. Even when the pressurization mechanism  170  is driven to supply the liquid, the reservoir portion  121  is maintained in the deflated state, and the reservoir amount SA becomes equal to or smaller than the second upper limit value V 2 . 
     As illustrated in  FIG. 6 , the liquid is supplied to the liquid ejecting portion  41  through the first liquid flow path  111 , the inflow portion  125 , the outflow portion  124 , and the second liquid flow path  112 . When the liquid is consumed in the liquid ejecting portion  41 , the remaining amount Ra of the liquid supply source  101  is reduced by the amount of the consumed liquid. 
     As illustrated in  FIG. 12 , the control portion  60  takes the upper limit value of the reservoir amount SA as the first upper limit value V 1  when the remaining amount Ra of the liquid contained in the liquid supply source  101  is equal to or smaller than the predetermined value VP. When the remaining amount Ra is equal to or smaller than the predetermined value VP, the control portion  60  controls the pressure mechanism  150  to cause the reservoir amount SA to become equal to or smaller than the first upper limit value V 1 . The control portion  60  controls the pressure mechanism  150  in such a manner that, when the remaining amount Ra is equal to or smaller than the predetermined value VP, a lower pressure is applied to the outside of the bag-like member  122  than the pressure applied when the remaining amount Ra is greater than the predetermined value VP. Specifically, when the remaining amount Ra becomes equal to the predetermined value VP, the control portion  60  releases the pressurization of the interior of the pressure chamber  151 . 
     The release of the pressurization may be carried out by driving the pump  153  for depressurization, or by opening the pressure chamber  151  to the atmosphere. When the pressurization is released, the bag-like member  122  is inflated due to the pressure by which the pressurization mechanism  170  supplies the liquid from the liquid supply source  101 , whereby the volume of the reservoir portion  121  is increased. 
     When the predetermined value VP is equal to or greater than the first upper limit value V 1 , the bag-like member  122  is inflated until it comes into contact with the inner wall  154  of the holding portion  152 , and the liquid of the first upper limit value V 1  is stored in the reservoir portion  121 . Accordingly, the control portion  60  controls the pressure mechanism  150  to adjust the reservoir amount SA so that the reservoir amount SA becomes equal to the first upper limit value V 1  when the remaining amount Ra becomes equal to the predetermined value VP. 
     When a difference between the predetermined value VP and the limit value VL is greater than a difference between the first upper limit value V 1  and the second upper limit value V 2 , the remaining amount Ra after the remaining amount Ra becomes equal to the predetermined value VP and the liquid is supplied to the reservoir portion  121 , is greater than the limit value VL. Because of this, the control portion  60  acts to supply the liquid from the liquid supply source  101  until the remaining amount Ra becomes equal to the limit value VL. Accordingly, the reservoir amount SA is maintained at the first upper limit value V 1 , and the reservoir amount SA is reduced. 
     When the remaining amount Ra becomes equal to the limit value VL, the control portion  60  stops the driving of the pressurization mechanism  170  and pressurizes the outside of the bag-like member  122 . To be specific, the control portion  60  drives the pump  153  for pressurization to pressurize the liquid in the reservoir portion  121  from the outside of the bag-like member  122 . When the liquid has been consumed in the liquid ejecting portion  41 , the liquid is supplied from the reservoir portion  121  to the liquid ejecting portion  41  by the amount of the liquid having been consumed. The bag-like member  122  is deflated by the amount of the liquid having been supplied, so that the volume of the reservoir portion  121  is reduced. 
     For example, the first upper limit value V 1  may be an amount of liquid that is expected to be used for printing one image. With this, even when the liquid in the liquid supply source  101  is exhausted during the printing of an image, the printing of the image may be continued by using the liquid stored in the reservoir portion  121 . This reduces a risk of the interruption of printing. Further, it is possible to suppress deterioration in print quality such as color unevenness due to the interruption of printing. 
     When the liquid supply source  101  is replaced and the remaining amount Ra becomes larger than the predetermined value VP, the control portion  60  drives the pressurization mechanism  170 . The pressure at which the pressurization mechanism  170  pressurizes the liquid and delivers it to the reservoir portion  121  is smaller than the pressure at which the pressure mechanism  150  pressurizes the bag-like member  122 . Therefore, when the reservoir amount SA is greater than the second upper limit value V 2 , the liquid stored in the reservoir portion  121  is supplied first to the liquid ejecting portion  41 . The reservoir portion  121  is deflated until the opposing inner surfaces of the bag-like member  122  are brought into contact with each other, and the reservoir amount SA becomes equal to or smaller than the second upper limit value V 2 . When the reservoir amount SA becomes equal to or smaller than the second upper limit value V 2 , the liquid contained in the liquid supply source  101  is supplied to the liquid ejecting portion  41 . 
     Effects of the second embodiment will be described below. 
     8. For example, when the liquid of the first upper limit value V 1  is stored in the reservoir portion  121  regardless of the remaining amount Ra, a period of time for which the liquid stays in the reservoir portion  121  becomes long so that the settling components are likely to settle. In this regard, when the remaining amount Ra of the liquid contained in the liquid supply source  101  is greater than the predetermined value VP, the control portion  60  causes the reservoir amount SA to be smaller than the first upper limit value V 1 . As a result, while the remaining amount Ra is greater than the predetermined value VP, the reservoir amount SA becomes small so that the period of time for which the liquid stays in the reservoir portion  121  can be shortened. Accordingly, it is possible to reduce the risk of the progress of the settling of the settling components, and to reduce the risk that the liquid in which the settling of the settling components has progressed is supplied to the liquid ejecting portion  41 . 
     9. When the remaining amount Ra becomes equal to the predetermined value VP, the control portion  60  controls the pressure mechanism  150  to cause the reservoir amount SA to become equal to the first upper limit value V 1 . Accordingly, even when the liquid is unable to be supplied from the liquid supply source  101  to the reservoir portion  121  like in a case where the liquid supply source  101  is detached from the liquid supply source holding portion  102  to be replaced, for example, the liquid stored in the reservoir portion  121  can be supplied to the liquid ejecting portion  41 . 
     10. The reservoir portion  121  includes the bag-like member  122  formed of the flexible member  133 . The bag-like member  122  having flexibility is deformed by pressure applied to the outside of the bag-like member  122 , so that the volume of the interior of the bag-like member  122  is changed. Accordingly, the configuration in which the pressure mechanism  150  applies the pressure to the outside of the bag-like member  122  may be suitably employed as a configuration for adjusting the reservoir amount SA. 
     11. The volume of the interior of the bag-like member  122  becomes larger as the pressure applied to the outside of the bag-like member  122  is lower. In this respect, when the remaining amount Ra is equal to or smaller than the predetermined value VP, a lower pressure is applied to the outside of the bag-like member  122  than the pressure applied when the remaining amount Ra is greater than the predetermined value VP, thereby making it possible to increase the volume of the interior of the bag-like member  122 . Therefore, it is possible to suitably employ the above mechanism as a mechanism for changing the volume of the interior of the bag-like member  122 . 
     12. When the remaining amount Ra is greater than the predetermined value VP, the opposing inner surfaces among the inner surfaces included in the bag-like member  122  make contact with each other. With this, the volume of the interior of the bag-like member  122  becomes small, so that the reservoir amount SA of the liquid stored in the bag-like member  122  becomes significantly small. This makes it possible to shorten the period of time for which the liquid stays in the reservoir portion  121 , and reduce the risk that the liquid in which the settling of the settling components has progressed is supplied to the liquid ejecting portion  41 . 
     Third Embodiment 
     Next, a third embodiment of a liquid ejecting apparatus and a control method for a liquid ejecting apparatus will be described with reference to the accompanying drawings. The third embodiment is different from the second embodiment in the configuration of a reservoir portion. Since other points are substantially the same as those of the second embodiment, the same reference numerals are given to the same constituent elements so as to omit redundant description thereof. 
     As illustrated in  FIG. 16 , a discharge mechanism  50  may include a first atmospheric open valve  55 . When the first atmospheric open valve  55  is opened, a space enclosed by a cap  51  and a liquid ejecting portion  41  is opened to the atmosphere. The first atmospheric open valve  55  may be closed when a negative pressure is applied to a nozzle  44 , and opened when the interior of the cap  51  is allowed to communicate with the atmosphere. 
     A liquid supply source  101  may include a case  107 , and a liquid pack  109  accommodated in an air chamber  108  formed inside the case  107 . The liquid pack  109  is constituted by a flexible film formed in a bag-like shape, for example. 
     A liquid supply source holding portion  102  may be disposed such that a position of a liquid in the liquid supply source  101  attached to the liquid supply source holding portion  102  is lower than a position at which the nozzle  44  of the liquid ejecting portion  41  opens, and also lower than a position of a liquid level when the amount of the liquid stored in a reservoir portion  121  is equal to a lower limit value Vm. 
     A pressure mechanism  150  includes a reservoir amount sensor  360  for detecting a reservoir amount SA of the liquid stored in the reservoir portion  121 , and a supply mechanism  361  for supplying the liquid contained in the liquid supply source  101  to the reservoir portion  121 . The supply mechanism  361  may include a coupling flow path  362  coupled to the liquid supply source  101  in a state of being attached to the liquid supply source holding portion  102 , a pressurization pump  363  disposed in the coupling flow path  362 , a pressure sensor  364 , and an air pressure adjustment portion  365 . The pressurization pump  363  supplies a pressurized air to the air chamber  108  through the coupling flow path  362 . The pressurization pump  363  crushes the liquid pack  109  by the pressurizing force of the pressurized air supplied into the air chamber  108  to supply the liquid in the liquid pack  109  to the reservoir portion  121  through a liquid supply flow path  110 . 
     The reservoir portion  121  may be mounted in the carriage  43  and may be provided in a movable manner together with the carriage  43 . When the liquid level of the liquid stored in the reservoir portion  121  is positioned above the opening of the nozzle  44  in the liquid ejecting portion  41 , a hydraulic pressure adjustment mechanism  280  may be provided between the reservoir portion  121  and the liquid ejecting portion  41  in the liquid supply flow path  110 . 
     The reservoir portion  121  of the present embodiment is provided between a static mixer  250  and a degassing mechanism  270 . The reservoir portion  121  may be constituted of, for example, a rigid member. The reservoir portion  121  includes a reservoir chamber  120 A having a constant volume. The reservoir portion  121  stores a liquid of an amount equal to or smaller than a first upper limit value V 1 . When the first upper limit value V 1  is smaller than the volume of the reservoir chamber  120 A, there is a region where the liquid is present and a region where a gas is present within the reservoir chamber  120 A. The reservoir portion  121  may include a second atmospheric open valve  366  for opening the reservoir chamber  120 A to the atmosphere. 
     The reservoir amount sensor  360  is able to detect the first upper limit value V 1  and a second upper limit value V 2  of the reservoir amount SA which is smaller than the first upper limit value V 1 . The reservoir amount sensor  360  may detect the lower limit value Vm. The reservoir amount sensor  360  may be a sensor for detecting a position of the liquid level in the reservoir chamber  120 A. The control portion  60  may determine which of the first upper limit value V 1 , the second upper limit value V 2 , and the lower limit value Vm the reservoir amount SA has come to be, based on the position of the liquid level detected by the reservoir amount sensor  360 . The reservoir amount sensor  360  may detect a situation in which the reservoir amount SA has come to be one of the first upper limit value V 1 , the second upper limit value V 2 , and the lower limit value Vm. 
     Operations of the present embodiment will be described. 
     The control portion  60  may drive the pressurization pump  363  in a state where an on-off valve  140  is opened when the liquid is supplied from the liquid supply source  101 , or may drive the pressurization pump  363  in a state where the on-off valve  140  is closed in advance to maintain the air chamber  108  in a pressurized state. In the case where the air chamber  108  is maintained in the pressurized state, the liquid is supplied from the liquid supply source  101  to the reservoir portion  121  when the on-off valve  140  is opened. When the pressure in the air chamber  108  is lowered as a result of supplying the liquid, the control portion  60  drives the pressurization pump  363  based on the detection result of the pressure sensor  364 . 
     The control portion  60  drives and controls the supply mechanism  361  so that the reservoir amount SA detected by the reservoir amount sensor  360  becomes equal to or smaller than the second upper limit value V 2  when a remaining amount Ra is greater than a predetermined value VP. The control portion  60  detects the reservoir amount SA by the reservoir amount sensor  360 , and opens the on-off valve  140  when the reservoir amount SA becomes equal to the lower limit value Vm. When the liquid is supplied from the liquid supply source  101  to the reservoir portion  121 , the reservoir amount SA increases. The control portion  60  closes the on-off valve  140  to cause the reservoir amount SA to be equal to or smaller than the second upper limit value V 2 . 
     The control portion  60  drives and controls the supply mechanism  361  so that the reservoir amount SA becomes equal to or smaller than the first upper limit value V 1  when the remaining amount Ra is equal to or smaller than the predetermined value VP. The control portion  60  opens the on-off valve  140  when the reservoir amount SA becomes equal to the lower limit value Vm. The control portion  60  closes the on-off valve  140  to cause the reservoir amount SA to be equal to or smaller than the first upper limit value V 1 . 
     The control portion  60  may return the liquid in the reservoir chamber  120 A to the liquid supply source  101  when a stay of the liquid in the reservoir portion  121  exceeds a set time or when the power supply of the liquid ejecting apparatus  10  is to be turned off. Specifically, the control portion  60  opens the on-off valve  140  in a state in which the air chamber  108  is opened to the atmosphere. The liquid in the reservoir chamber  120 A is moved to the liquid supply source  101  by the water head (energy possessed by the liquid) because the liquid level of the liquid stored in the reservoir portion  121  is positioned above the liquid position in the liquid supply source  101  attached to the liquid supply source holding portion  102 . When the reservoir amount SA becomes equal to the lower limit value Vm, the control portion  60  closes the on-off valve  140 . After the on-off valve  140  is closed or when the power supply of the liquid ejecting apparatus  10  is turned on, the control portion  60  may urge an operator to detach the liquid supply source  101  from the liquid supply source holding section  102  and shake the detached liquid supply source  101  so as to stir the liquid contained therein, or may drive an agitator mechanism (not illustrated) provided in the liquid supply source holding portion  102 . 
     Effects of the third embodiment will be described below. 
     13. The reservoir amount sensor  360  detects the reservoir amount SA of the liquid stored in the reservoir portion  121 . When the remaining amount Ra is greater than the predetermined value VP, the control portion  60  supplies the liquid to the reservoir portion  121  from the liquid supply source  101  so that the reservoir amount SA becomes equal to or smaller than the second upper limit value V 2 . When the remaining amount Ra is equal to or smaller than the predetermined value VP, the control portion  60  supplies the liquid to the reservoir portion  121  from the liquid supply source  101  so that the reservoir amount SA becomes equal to or smaller than the first upper limit value V 1 , which is greater than the second upper limit value V 2 . Accordingly, the above-discussed configuration can be suitably employed as a configuration in which the reservoir amount SA is reduced while the remaining amount Ra is greater than the predetermined value VP, and the remaining amount SA is increased when the remaining amount Ra becomes equal to or smaller than the predetermined value VP. 
     The present embodiment may be modified and implemented as follows. The present embodiment and the following modifications may be implemented in combination with each other within a range where no technical contradiction exists. 
     As illustrated in  FIG. 17 , a supply mechanism  361  may depressurize the interior of a reservoir portion  121  to supply a liquid from a liquid supply source  101  to the reservoir portion  121 . The supply mechanism  361  may include a coupling flow path  362  coupled to a reservoir chamber  120 A, an exhaust pump  367  disposed in the coupling flow path  362 , a pressure sensor  364 , and an air pressure adjustment portion  365 . The control portion  60  may drive the exhaust pump  367  in a state where an on-off valve  140  is opened, and may supply the liquid to the reservoir portion  121  from the liquid supply source  101 . 
     When the flexible members  133  are bonded while pinching the connection body  123 , a gap is generated between the flexible member  133  and the connection body  123  near the connection body  123 . The gap is larger as the thickness of the connection body  123  is larger and the inner surfaces of the bag-like member  122  are farther separated from each other. Therefore, in a case in which the reservoir amount adjustment mechanism  150  applies pressure to the outside of the bag-like member  122 , when the connection body  123  has such a thickness that a gap is formed between the connection body  123  and the flexible member  133 , the coupling path  136  may not be provided. 
     The remaining amount acquisition portion  103  may be a terminal that is coupled to a storage portion included in the liquid supply source  101  and acquires information indicating the remaining amount Ra from the storage portion. The control portion  60  may determine whether the remaining amount Ra of the liquid contained in the liquid supply source  101  is equal to or smaller than the predetermined value VP or equal to or smaller than the limit value VL based on the information stored in the storage portion and the amount of the liquid consumed by the liquid ejecting apparatus  10 . 
     The difference between the predetermined value VP and the limit value VL may be smaller than the difference between the first upper limit value V 1  and the second upper limit value V 2 . The reservoir amount SA when the remaining amount Ra becomes equal to the predetermined value VP, may be smaller than the first upper limit value V 1 . 
     The second upper limit value V 2  may be the reservoir amount SA in a state where the opposing inner surfaces of the bag-like member  122  are separated from each other. For example, the pressurization mechanism  170  may supply the liquid with such pressure that the inner surfaces of the bag-like member  122  are separated from each other. 
     The pressure mechanism  150  may include a spring configured to push the bag-like member  122  from the outside thereof. The pressure mechanism  150  may push the bag-like member  122  with the spring to make the reservoir amount SA equal to or smaller than the second upper limit value V 2  when the remaining amount Ra is greater than the predetermined value VP, and may depressurize the interior of the pressure chamber  151  to make the reservoir amount SA equal to or smaller than first upper limit value V 1  when the remaining amount Ra is equal to or smaller than the predetermined value VP. 
     The reservoir portion  121  may be constituted by, for example, a cylinder and a piston. The pressure mechanism  150  may adjust the reservoir amount SA by mechanically moving the piston. 
     The predetermined value VP may be smaller than the first upper limit value V 1 . When the remaining amount Ra becomes equal to the predetermined value VP, the control portion  60  may supply the liquid contained in the liquid supply source  101  to the reservoir portion  121  and may urges the replacement of the liquid supply source  101 . At this time, the reservoir amount SA may be smaller than the first upper limit value V 1 . 
     The bag-like member  122  may be formed by a sheet of flexible member  133 . 
     Technical ideas and operational advantages understood from the above embodiments and modifications will be described below. 
     A liquid ejecting apparatus includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply source holding portion configured to attach and detach a liquid supply source for containing the liquid; a liquid supply flow path configured to supply the liquid from the liquid supply source attached to the liquid supply source holding portion to the liquid ejecting portion; a reservoir portion provided in the liquid supply flow path and configured to store the liquid; a reservoir amount adjustment mechanism configured to adjust a reservoir amount of the liquid stored in the reservoir portion; and a control portion configured to control the reservoir amount adjustment mechanism in such a manner that, when an upper limit value of the reservoir amount is defined as a first upper limit value in a case in which a remaining amount of the liquid contained in the liquid supply source is equal to or smaller than a predetermined value, the reservoir amount when the remaining amount is larger than the predetermined value is caused to be smaller than the first upper limit value. 
     For example, when a liquid of the first upper limit value is stored in the reservoir portion regardless of the remaining amount, the time for which the liquid stays in the reservoir portion becomes long so that the settling components are likely to settle. In this regard, according to this configuration, when the remaining amount of the liquid contained in the liquid supply source is larger than the predetermined value, the control portion causes the reservoir amount to be smaller than the first upper limit value. As a result, while the remaining amount is larger than the predetermined value, the reservoir amount becomes small so that the time for which the liquid stays in the reservoir portion can be shortened. Accordingly, it is possible to reduce the risk of the progress of the settling of the settling components, and reduce the risk that the liquid in which the settling of the settling components has progressed is supplied to the liquid ejecting portion. 
     In the liquid ejecting apparatus, the predetermined value may be equal to or larger than the first upper limit value, and the control portion may control the reservoir amount adjustment mechanism in such a manner that the reservoir amount becomes equal to the first upper limit value when the remaining amount becomes equal to the predetermined value. 
     According to this configuration, when the remaining amount becomes equal to the predetermined value, the control portion controls the reservoir amount adjustment mechanism to cause the reservoir amount to be equal to the first upper limit value. Accordingly, even when the liquid is unable to be supplied from the liquid supply source to the reservoir portion like in a case where the liquid supply source is detached from the holding portion to be replaced, for example, the liquid stored in the reservoir portion can be supplied to the liquid ejecting portion. 
     In the liquid ejecting apparatus, the reservoir portion may include a bag-like member formed of a flexible member having flexibility, and a connection body coupled to the liquid supply flow path, and the reservoir amount adjustment mechanism may change a volume of the interior of the bag-like member by applying pressure to the outside of the bag-like member so as to adjust the reservoir amount. 
     According to this configuration, the reservoir portion includes the bag-like member formed of the flexible member. The bag-like member having flexibility is deformed by the pressure applied to the outside of the bag-like member, so that the volume of the interior of the bag-like member is changed. Accordingly, the configuration in which the reservoir amount adjustment mechanism applies the pressure to the outside of the bag-like member may be suitably employed as a configuration for adjusting the reservoir amount. 
     In the liquid ejecting apparatus, the control portion may control the reservoir amount adjustment mechanism in such a manner that, when the remaining amount is equal to or smaller than the predetermined value, a lower pressure may be applied to the outside of the bag-like member than the pressure applied when the remaining amount is larger than the predetermined value. 
     The volume of the interior of the bag-like member becomes larger as the pressure applied to the outside of the bag-like member is lower. In this respect, according to this configuration, when the remaining amount is equal to or smaller than the predetermined value, a lower pressure is applied to the outside of the bag-like member than the pressure applied when the remaining amount is larger than the predetermined value, thereby making it possible to increase the volume of the interior of the bag-like member. Therefore, it is possible to suitably employ the above mechanism as a mechanism for changing the volume of the interior of the bag-like member. 
     In the liquid ejecting apparatus, when the remaining amount is larger than the predetermined value, the opposing inner surfaces of the bag-like member may be in contact with each other in the reservoir portion. 
     According to this configuration, when the remaining amount is larger than the predetermined value, the opposing inner surfaces among the inner surfaces included in the bag-like member make contact with each other. With this, the volume of the interior of the bag-like member becomes small, so that the reservoir amount of the liquid stored in the bag-like member becomes significantly small. This makes it possible to shorten the time for which the liquid stays in the reservoir portion, and reduce the risk that the liquid in which the settling of the settling components has progressed is supplied to the liquid ejecting portion. 
     In the liquid ejecting apparatus, the reservoir amount adjustment mechanism may include a reservoir amount sensor configured to detect the first upper limit value and a second upper limit value of the reservoir amount smaller than the first upper limit value, and a supply mechanism for supplying the liquid contained in the liquid supply source to the reservoir portion. The control portion may drive and control the supply mechanism to cause the reservoir amount detected by the reservoir amount sensor to be equal to or smaller than the second upper limit value when the remaining amount is larger than the predetermined value, and may drive and control the supply mechanism to cause the reservoir amount to be equal to or smaller than the first upper limit value when the remaining amount is equal to or smaller than the predetermined value. 
     According to this configuration, the reservoir amount sensor detects the reservoir amount of the liquid stored in the reservoir portion. When the remaining amount is larger than the predetermined value, the control portion supplies the liquid to the reservoir portion from the liquid supply source so that the reservoir amount becomes equal to or smaller than the second upper limit value. When the remaining amount is equal to or smaller than the predetermined value, the control portion supplies the liquid to the reservoir portion from the liquid supply source so that the reservoir amount becomes equal to or smaller than the first upper limit value, which is larger than the second upper limit value. Accordingly, the above-discussed configuration can be suitably employed as a configuration in which the reservoir amount is reduced while the remaining amount is larger than the predetermined value, and the remaining amount is increased when the remaining amount becomes equal to or smaller than the predetermined value. 
     A control method for a liquid ejecting apparatus is a control method for the liquid ejecting apparatus that includes a liquid ejecting portion configured to eject a liquid through a nozzle; a liquid supply flow path configured to supply the liquid contained in a liquid supply source to the liquid ejecting portion; and a reservoir portion provided in the liquid supply flow path and configured to store the liquid. The method includes, when an upper limit value of a reservoir amount of the liquid stored in the reservoir portion is defined as a first upper limit value in a case in which a remaining amount of the liquid contained in the liquid supply source is equal to or smaller than a predetermined value, performing adjustment in such a manner that the reservoir amount when the remaining amount is larger than the predetermined value is caused to be smaller than the first upper limit value. According to this method, the same effects as those in the liquid ejecting apparatus may be achieved. 
     In the control method for the liquid ejecting apparatus, the predetermined value may be equal to or larger than the first upper limit value, and the reservoir amount may be so adjusted as to be equal to the first upper limit value when the remaining amount becomes equal to the predetermined value. According to this method, the same effects as those in the liquid ejecting apparatus may be achieved.