Patent ID: 12233652

DESCRIPTION OF EXEMPLARY EMBODIMENTS

With reference to the accompanying drawings, a tank unit according to some exemplary embodiments of the present disclosure, and a liquid ejecting apparatus equipped therewith, will now be explained. The liquid ejecting apparatus disclosed herein is, for example, an ink-jet printer that performs printing by ejecting ink, which is an example of liquid, onto a medium such as paper.

In the drawings, it is assumed that a liquid ejecting apparatus11is installed on a horizontal plane, and, based on this assumption, the direction of gravity is indicated by a Z axis, and the directions along the horizontal plane are indicated by an X axis and a Y axis. The X, Y, and Z axes are orthogonal to one another. When the user stands in front of the liquid ejecting apparatus11in a facing manner, the Y axis represents the direction of the depth of the liquid ejecting apparatus11, and the X axis represents the direction of the width of the liquid ejecting apparatus11.

Overall Structure of Liquid Ejecting Apparatus

As illustrated inFIG.1, the liquid ejecting apparatus11may include a medium container portion13, which is capable of containing a medium12inside, a stacker14, which receives the medium12after printing, and an operation portion15, which is used for operating the liquid ejecting apparatus11. The operation portion15may be, for example, a touch panel. The operation portion15, a touch panel, may include a display portion15acapable of displaying various kinds of operation screen and various kinds of message, etc. The liquid ejecting apparatus11may include an image reading portion16, which reads an image of a document, and an automatic feeding portion17, which feeds the document to the image reading portion16.

The liquid ejecting apparatus11includes a control portion19, which controls various kinds of operation performed in the liquid ejecting apparatus11. The control portion19can be configured as circuitry that includes: (1) one or more processors configured to operate in accordance with computer programs (software), (2) one or more specific-purpose hardware circuits such as specific-purpose hardware (application specific integrated circuit (ASIC)) configured to perform at least a part of various kinds of processing, or (3) a combination of them. The processor includes a CPU and a memory such as a RAM and a ROM, etc. Program codes or commands configured to cause the CPU to perform processing are stored in the memory. The “memory”, namely, a computer-readable medium, encompasses every kind of available medium that is accessible by a general-purpose or specific-purpose computer.

The liquid ejecting apparatus11includes a tank unit26. The tank unit26may include an attachment portion28to which one or more liquid containers24can be detachably attached. The attachment portion28may have a plurality of slots corresponding respectively to the plurality of liquid containers24. The attachment portion28has an insertion opening28othrough which the liquid containers24are configured to be inserted. The insertion opening28ois, for example, open at the front of the liquid ejecting apparatus11. In this case, for example, the liquid containers24are configured to be inserted through the insertion opening28oin the direction along the Y axis from the front of the liquid ejecting apparatus11. The liquid ejecting apparatus11may include a non-illustrated cover configured to cover the insertion opening28o. The cover may be movable between a position for covering the insertion opening28oand a position for exposing the insertion opening28o.

Plural different kinds of liquid, for example, plural kinds of ink different in color from one another, may be contained in the plurality of liquid containers24(24C,24M,24Y, and24K) respectively. For example, cyan ink, magenta ink, yellow ink, and black ink are contained in the liquid containers24C,24M,24Y, and24K respectively. The amount of liquid contained in the plurality of liquid containers24may be different between any two or more of them. For example, the amount of liquid contained in the liquid container24K, namely, black ink, may be larger than the amount of liquid contained in the liquid container24C,24M,24Y. The width of the liquid container24K, namely, its length along the X axis, may be greater than that of the liquid container24C,24M,24Y. The direction in which the liquid containers24can be inserted into the tank unit26is not limited to the direction along the Y axis. It may be the direction along the X axis, the direction along the Z axis, an oblique direction intersecting with at least one of the X, Y, and Z axes at an acute angle, or the like.

Structure of Supply Unit25

Next, with reference toFIG.2, a structure of a supply unit25will now be explained.

As illustrated inFIG.2, the liquid ejecting apparatus11includes a liquid ejecting head23, a supply unit25, and a supply flow passage37. Liquid is supplied from the supply unit25to the liquid ejecting head23through the supply flow passage37.

The supply unit25includes the tank unit26, which includes two reservoir portions33and35for storing liquid. The supply unit25may include a drive mechanism27configured to drive the tank unit26.

The tank unit26is configured such that liquid supplied from the liquid container24flows into it and the liquid flows out of it toward the liquid ejecting head23configured to eject the liquid. The tank unit26includes a first inlet portion60, a first reservoir portion33, a second reservoir portion35, and an outlet flow passage34. The first reservoir portion33is in communication with the second reservoir portion35through the outlet flow passage34. An on-off valve36is provided somewhere between the ends of the outlet flow passage34. The first reservoir portion33is located upstream of the second reservoir portion35in the direction in which the liquid flows when supplied from the liquid container24toward the liquid ejecting head23. The first reservoir portion33serves as a sub tank for temporarily retaining the liquid having flowed into the first reservoir portion33from the liquid container24. The second reservoir portion35serves as a reservoir tank for temporarily retaining the liquid having flowed into the second reservoir portion35from the first reservoir portion33until the liquid is supplied to the liquid ejecting head23.

The liquid having flowed in from the liquid container24that is in an attached state is stored in the first reservoir portion33. When the liquid stored in the second reservoir portion35is consumed as a result of the supply of this liquid out of the second reservoir portion35to the liquid ejecting head23, the on-off valve36opens, and replenishment liquid for making up for the consumption is supplied from the first reservoir portion33to the second reservoir portion35through the outlet flow passage34. The on-off valve36may be a one-way valve. The on-off valve36, a one-way valve, tolerates flow of the liquid from a first chamber62toward a second chamber68and does not tolerate flow of the liquid from the second chamber68toward the first chamber62.

The first reservoir portion33includes the first chamber62(sub tank chamber) configured to store the liquid supplied from the liquid container24. The second reservoir portion35includes the second chamber68(reservoir tank chamber) configured to store the liquid supplied from the first chamber62through the outlet flow passage34when the on-off valve36is open. The first chamber62is in communication with the second chamber68through the outlet flow passage34. Though the above-mentioned on-off valve36provided on the outlet flow passage34may be controlled by the control portion19, in the present embodiment, it is a differential pressure regulating valve capable of being opened and closed by a hydraulic head difference. A detailed structure of the on-off valve36will be explained later.

As illustrated inFIG.2, the tank unit26having the above structure includes a first opening-to-atmosphere portion64and a second opening-to-atmosphere portion69, in addition to the first inlet portion60, the first chamber62, the outlet flow passage34, the second chamber68, and the on-off valve36. The first opening-to-atmosphere portion64is able to open the inside of the first chamber62to atmosphere. The first opening-to-atmosphere portion64is open to a space over a first liquid surface66indicating the level of the liquid stored in the first chamber62. The second opening-to-atmosphere portion69is able to open the inside of the second chamber68to atmosphere. The second opening-to-atmosphere portion69is open to a space over a second liquid surface70indicating the level of the liquid stored in the second chamber68.

The first opening-to-atmosphere portion64may be configured to be switchable between an open-to-atmosphere state, in which the inside of the first chamber62is open to atmosphere, and a non-open-to-atmosphere state, in which the inside of the first chamber62is not open to atmosphere. The second opening-to-atmosphere portion69may be configured to be switchable between an open-to-atmosphere state, in which the inside of the second chamber68is open to atmosphere, and a pressurized state, in which the inside of the second chamber68is at a pressure higher than atmospheric pressure.

The liquid ejecting apparatus11includes the liquid ejecting head23, which is capable of ejecting liquid, and the supply flow passage37via which the tank unit26having the above structure is in communication with the liquid ejecting head23. The liquid stored in the tank unit26is supplied to the liquid ejecting head23through the supply flow passage37. The liquid ejecting head23ejects the liquid supplied from the tank unit26through the supply flow passage37. The liquid ejecting apparatus11may further include a collection flow passage39, through which the liquid ejecting head23is in communication with the tank unit26. That is, the liquid ejecting apparatus11may include the supply flow passage37, through which the liquid stored in the tank unit26is supplied to the liquid ejecting head23, and the collection flow passage39, through which the liquid is collected from the liquid ejecting head23to the tank unit26. As described here, the liquid ejecting apparatus11may be configured to circulate the liquid between the tank unit26and the liquid ejecting head23through the supply flow passage37and the collection flow passage39.

For example, liquid heated using a non-illustrated heater may be circulated between the tank unit26and the liquid ejecting head23so that the liquid ejecting apparatus11will be able to eject the liquid having a predetermined temperature from the liquid ejecting head23. As another example, when the liquid is pigment-based ink, by circulating the liquid between the tank unit26and the liquid ejecting head23, the liquid ejecting apparatus11may be configured to eject the liquid containing pigments dispersed uniformly therein from the liquid ejecting head23, while suppressing the precipitation of the pigments in the liquid by utilizing stirring effects produced by the circulation of the liquid. Of course, the liquid may be circulated between the tank unit26and the liquid ejecting head23for any other purpose.

The liquid ejecting apparatus11may include the liquid ejecting head23, the tank unit26, the supply flow passage37, a second inlet portion75, and the collection flow passage39. The tank unit26may include an outlet portion74, via which the liquid contained inside flows out toward the liquid ejecting head23through the supply flow passage37, and the second inlet portion75, via which the liquid collected from the liquid ejecting head23through the collection flow passage39flows in. The supply flow passage37provides communication between the outlet portion74and the liquid ejecting head23. The collection flow passage39provides communication between the liquid ejecting head23and the second inlet portion75.

As illustrated inFIG.2, when a liquid circulation system is adopted in the liquid ejecting apparatus11, the liquid stored in the second chamber68may flow through the supply flow passage37to the liquid ejecting head23, and the liquid returning from the liquid ejecting head23may flow through the collection flow passage39to the first chamber62. In this case, the outlet portion74may be provided on the second reservoir portion35, and the second inlet portion75may be provided on the first reservoir portion33(seeFIGS.8and10).

The liquid ejecting head23has one or more nozzles22and a nozzle surface21, in which these nozzles22are formed. The tank unit26is configured to supply the liquid contained in the liquid container24to the liquid ejecting head23through the first reservoir portion33, the outlet flow passage34, the second reservoir portion35, and the supply flow passage37. The liquid ejecting head23is configured to eject the supplied liquid from the nozzles22.

The liquid ejecting apparatus11, if equipped with a plurality of supply units25corresponding to different colors, is able to perform color printing by ejecting ink of the plurality of colors. A single drive mechanism27may drive a plurality of tank units26together. The liquid ejecting apparatus11may include a plurality of drive mechanisms27configured to drive a plurality of tank units26individually.

The liquid ejecting head23may be detachably attached to the body of the liquid ejecting apparatus11. The liquid ejecting head23may be in a tilted position such that its nozzle surface21is inclined with respect to a horizontal plane. The liquid ejecting head23may, in a tilted position, perform printing by ejecting liquid toward the medium12. The liquid ejecting head23may be a line-type head oriented in the direction of the width of the medium12. The liquid ejecting head23may be a serial-type head configured to perform printing while moving in the direction of the width of the medium12.

The liquid container24may have a containing chamber29that contains liquid. The liquid contained in the containing chamber29flows out via a pouring outlet portion30. The pouring outlet portion30may include an outlet valve31. The containing chamber29is, for example, a hermetically-closed space that is not in communication with atmosphere. The liquid container24before being attached to the attachment portion28may contain a larger amount of liquid than an amount of liquid that can be stored in the tank unit26.

The supply unit25may include a supply valve38, which can close the supply flow passage37, the collection flow passage39, a circulation valve40, which can open and close the collection flow passage39, and a liquid chamber41. The liquid chamber41is located somewhere between the ends of the collection flow passage39. The collection flow passage39has, as the ends, an upstream end connected to the liquid ejecting head23and a downstream end connected to the first reservoir portion33. The collection flow passage39is a flow passage through which the liquid present inside the liquid ejecting head23flows toward the tank unit26. The term “connected” as used herein shall be construed to encompass not only “directly connected”, “directly in (fluid) communication with” but also “indirectly connected”, “indirectly in (fluid) communication with”.

The liquid chamber41is located on the collection flow passage39, specifically, between the liquid ejecting head23and the circulation valve40. A part of the liquid chamber41is formed by a flexible member42. Elastic deformation of the flexible member42causes a change in the capacity of the liquid chamber41.

The liquid ejecting head23may include a first connection portion44, to which the collection flow passage39is connected, and a second connection portion45, to which the supply flow passage37is connected. The collection flow passage39has the upstream end connected to the first connection portion44and the downstream end connected to the first reservoir portion33. The supply flow passage37has an upstream end connected to the second reservoir portion35and a downstream end connected to the second connection portion45. The first connection portion44may be located at a position above the second connection portion45when the liquid ejecting head23is in a tilted position.

As illustrated inFIG.2, the liquid ejecting apparatus11may further include a pressurizing portion47. The pressurizing portion47may be in communication with the second opening-to-atmosphere portion69and be configured to apply pressure to the inside of the second chamber68. That is, the drive mechanism27may include the pressurizing portion47configured to apply pressure to the inside of the second reservoir portion35. The drive mechanism27may include a switching mechanism48, which is connected to the pressurizing portion47, and a pressure sensor49, which is configured to detect pressure. The drive mechanism27may include an opening-to-atmosphere path50, which is connected to the first reservoir portion33, a pressurizing flow passage51, which is connected to the second chamber68, and a connection flow passage52, which connects the opening-to-atmosphere path50and the pressurizing flow passage51to the pressurizing portion47. The drive mechanism27may include an air chamber53, which is partitioned off from the liquid chamber41by the flexible member42provided therebetween, a spring54, which is provided inside the air chamber53, and an air flow passage55, which is connected to the air chamber53. By pushing the flexible member42, the spring54reduces changes in pressure of the liquid inside the collection flow passage39and the liquid ejecting head23.

The pressurizing portion47is, for example, a tube pump that includes rollers and a tube. In this case, the tube pump sends air by causing its rollers to rotate while squeezing the tube by the rollers. The non-illustrated tube of the pressurizing portion471has a first end connected to the air flow passage55and a second end connected to the connection flow passage52. The pressurizing portion47, when driven in a forward direction, sends air taken in from the air flow passage55into the connection flow passage52. The pressurizing portion47, when driven in a reverse direction, sends air taken in from the connection flow passage52into the air flow passage55.

The supply unit25may include a pressurizing mechanism57configured to apply pressure to the liquid present inside the supply flow passage37. The pressurizing mechanism57includes the pressurizing portion47, the air chamber53, and the air flow passage55. The supply unit25may include a fine pressurizing portion58located on the collection flow passage39between the liquid ejecting head23and the circulation valve40. The fine pressurizing portion58includes the pressurizing mechanism57and the liquid chamber41. The fine pressurizing portion58is configured to apply pressure to the liquid present inside the collection flow passage39. More particularly, the pressurizing mechanism57pressurizes the flexible member42from the outside of the liquid chamber41.

Structure of First Reservoir Portion33

Next, the first reservoir portion33will now be explained.

The first reservoir portion33may include the first inlet portion60, the first chamber62, a liquid surface detecting portion63, and the first opening-to-atmosphere portion64The first inlet portion60may include an inlet valve61.

When the liquid container24is attached to the attachment portion28(seeFIG.1) of the tank unit26, the pouring outlet portion30becomes connected to the first inlet portion60, and the outlet valve31and the inlet valve61open. The valves31and61are kept in an open state when there exists the liquid container24attached to the attachment portion28. The inlet valve61may open earlier than the outlet valve31in the process of attachment of the liquid container24to the attachment portion28. Opening the inlet valve61earlier makes the leakage of liquid from the liquid container24less likely to occur.

Liquid supplied from the liquid container24flows in via the first inlet portion60. The first inlet portion60may be located over or above the first reservoir portion33. For example, the first inlet portion60may be provided through the ceiling65of the first chamber62. The lower end of the first inlet portion60may be located inside the first chamber62and may be located under or below the ceiling65. The upper end of the first inlet portion60may be located outside the first chamber62and may be located over or above the ceiling65. An example of a detailed structure of the first inlet portion60and the first chamber62will be explained later.

The first chamber62stores the liquid having flowed in via the first inlet portion60. The lower end of the first inlet portion60is located below the nozzle surface21. Therefore, the first liquid surface66of the liquid stored in the first chamber62changes in level within a range below the nozzle surface21. Specifically, due to a hydraulic head difference from the liquid stored in the first reservoir portion33, the liquid contained in the liquid container24flows via the pouring outlet portion30and the first inlet portion60into the first reservoir portion33.

The first opening-to-atmosphere portion64is able to open the inside of the first chamber62to atmosphere. The first opening-to-atmosphere portion64is made of, for example, a vapor-liquid separator film. The term “vapor-liquid separator film” as used herein means a film member that has a function of not allowing liquid to pass through itself and allowing air to pass through itself. The first opening-to-atmosphere portion64prevents the liquid stored in the first chamber62from leaking out and allows air to enter the first chamber62from the outside and to exit therefrom to the outside. Since the inside of the first chamber62is open to atmosphere as described above, the first liquid surface66changes in level due to a liquid inflow from the liquid container24via the first inlet portion60and due to a liquid outflow through the outlet flow passage34.

One end of the outlet flow passage34is connected to the first chamber62. The liquid stored in the first chamber62flows out through the outlet flow passage34.

The on-off valve36is able to open and close the outlet flow passage34. The on-off valve36may include a one-way valve that tolerates flow of the liquid from the first chamber62toward the second chamber68and does not tolerate flow of the liquid from the second chamber68toward the first chamber62. A detailed structure of the on-off valve36will be explained later.

When the liquid contained in the liquid container24flows into the first reservoir portion33via the pouring outlet portion30and the first inlet portion60, air flows from the first reservoir portion33into the liquid container24via the first inlet portion60and the pouring outlet portion30, wherein an amount of the air corresponds to an amount of the liquid flowing into the first reservoir portion33. In addition, the liquid-level position of the first liquid surface66rises by a level amount corresponding to the amount of the liquid flowing into the first reservoir portion33. When the first liquid surface66rising in level reaches the lower end of the first inlet portion60, the flow of the air from the first reservoir portion33into the liquid container24stops. Since the containing chamber29is hermetically closed, this stop of the flow of the air causes a decrease in the internal pressure of the containing chamber29corresponding to an amount of the liquid flowing in. Then, the flow of the liquid from the liquid container24into the first reservoir portion33stops when the negative pressure inside the containing chamber29becomes greater than the hydraulic head of the liquid contained in the containing chamber29.

When liquid flows from the first reservoir portion33to the second reservoir portion35, the liquid-level position of the first liquid surface66drops. When the first liquid surface66dropping in level falls below the lower end of the first inlet portion60, air flows into the containing chamber29via the first inlet portion60and the pouring outlet portion30, and the negative pressure inside the containing chamber29decreases. Then, the liquid contained in the liquid container24flows into the first reservoir portion33when the negative pressure inside the containing chamber29becomes less than the hydraulic head of the liquid contained in the containing chamber29. As a result, the first liquid surface66is kept at a standard level position SH that is a position near the lower end of the first inlet portion60while the liquid is present inside the liquid container24. The first liquid surface66is at a level below the standard level position SH when the liquid container24is running out of the liquid.

The tank unit26further includes the liquid surface detecting portion63configured to detect the surface level of the liquid stored in the first chamber62. The liquid surface detecting portion63may detect that the first liquid surface66is at the standard level position SH. The liquid surface detecting portion63may detect that the first liquid surface66is at a level below the standard level position SH. The liquid surface detecting portion63may detect that the first liquid surface66is at a full level position. The full level position is above the standard level position SH. The maximum amount of liquid is stored in the first reservoir portion33when the first liquid surface66is at the full level position. The control portion19may determine the liquid container24as being empty when the liquid surface detecting portion63detects that the first liquid surface66is at a level below the standard level position SH, and then may prompt the user to replace this liquid container24with another one.

The standard level position SH is set to be, for example, a position above the downstream end of the collection flow passage39in the first chamber62. If set so, when the first liquid surface66is at the standard level position SH, the liquid stored in the first reservoir portion33is able to flow into the liquid ejecting head23through the collection flow passage39.

Structure of Second Reservoir Portion35

Next, the second reservoir portion35will now be explained.

The second chamber68is connected to the other end of the outlet flow passage34. The second chamber68stores the liquid supplied from the first chamber62. The second reservoir portion35may include the second chamber68and the second opening-to-atmosphere portion69, by which the second chamber68is partitioned off from the pressurizing flow passage51.

The second opening-to-atmosphere portion69is able to open the inside of the second chamber68to atmosphere. The second opening-to-atmosphere portion69is made of, for example, a vapor-liquid separator film. This vapor-liquid separator film is a film member that has a function of allowing air to pass through itself and not allowing liquid to pass through itself, similarly to the vapor-liquid separator film of the first opening-to-atmosphere portion64.

The liquid stored in the first reservoir portion33flows into the second chamber68due to a hydraulic head difference from the liquid stored in the second reservoir portion35. When the internal pressure of the first chamber62and the internal pressure of the second chamber68are atmospheric pressure, the second liquid surface70of the liquid stored in the second reservoir portion35is the same in level as the first liquid surface66. In other words, the second liquid surface70is kept at the standard level position SH, which is almost the same as the level of the lower end of the first inlet portion60, and changes in level within a range below the nozzle surface21. The liquid present inside the liquid ejecting head23is kept to be in negative pressure due to a hydraulic head difference between the liquid stored in the first reservoir portion33and the liquid stored in the second reservoir portion35. When the liquid ejecting head23consumes the liquid, the liquid stored in the second reservoir portion35is supplied to the liquid ejecting head23.

When the on-off valve36includes a one-way valve, the one-way valve closes the outlet flow passage34when the internal pressure of the second reservoir portion35is higher than the internal pressure of the first reservoir portion33. Therefore, the one-way valve closes the outlet flow passage34when the pressurizing portion47applies pressure to the inside of the second reservoir portion35.

The control portion19(seeFIG.1) controls the open/close operation of the supply valve38and the circulation valve40. The supply valve38is capable of opening and closing the supply flow passage37when pressure is applied by the pressurizing portion47. The circulation valve40is capable of opening and closing the collection flow passage39.

Structure of Switching Mechanism48

Next, the switching mechanism48will now be explained.

The switching mechanism48includes a thin tube portion72, which is a part of the connection flow passage52, and first to eleventh selection valves73ato73k. The thin tube portion72is a meandering tube that is thin enough to the extent that the flow of liquid is significantly restricted in relation to the flow of air.

The air flow passage55comes into communication with atmosphere when the first selection valve73aopens. The air flow passage55comes into communication with the pressure sensor49when the second selection valve73bopens. When the third selection valve73copens, the air flow passage55opens, and the pressurizing portion47comes into communication with the air chamber53.

The connection flow passage52between the pressurizing portion47and the eighth selection valve73hcomes into communication with atmosphere when the fourth selection valve73dopens. The connection flow passage52comes into communication with the pressure sensor49when the fifth selection valve73eopens. The connection flow passage52comes into communication with atmosphere when the sixth selection valve73fand the seventh selection valve73gopen. The connection flow passage52opens when the eighth selection valve73hopens. The thin tube portion72comes into communication with atmosphere when the ninth selection valve73iopens. When the tenth selection valve73jopens, the opening-to-atmosphere path50opens, and the first reservoir portion33comes into communication with the connection flow passage52. When the eleventh selection valve73kopens, the pressurizing flow passage51opens, and the second reservoir portion35comes into communication with the connection flow passage52.

To change the internal pressure of the air chamber53, the switching mechanism48opens the second to fourth selection valves73bto73dand closes the other selection valves. When the pressurizing portion47is driven in the forward direction in this state, air that is present inside the air chamber53exits through the air flow passage55and the connection flow passage52and, therefore, the internal pressure of the air chamber53decreases. When the pressurizing portion47is driven in the reverse direction in this state, air is taken into the air chamber53through the connection flow passage52and the air flow passage55and, therefore, the internal pressure of the air chamber53increases. The pressure sensor49may detect the internal pressure of the air flow passage55and the air chamber53at this time. The control portion19(seeFIG.1) may control the driving of the pressurizing portion47based on the detection result of the pressure sensor49.

To open the first reservoir portion33to atmosphere, the switching mechanism48opens the sixth selection valve73fand the tenth selection valve73j. The first chamber62comes into communication with atmosphere through the opening-to-atmosphere path50and the connection flow passage52.

To open the second reservoir portion35to atmosphere, the switching mechanism48opens the seventh selection valve73gand the eleventh selection valve73k. The second chamber68comes into communication with atmosphere through the pressurizing flow passage51and the connection flow passage52.

To apply pressure to the inside of the second reservoir portion35, the switching mechanism48opens the first selection valve73a, the fifth selection valve73e, the eighth selection valve73h, and the eleventh selection valve73k, and closes the other selection valves. When the pressurizing portion47is driven in the forward direction in this state, air flows into the second chamber68through the air flow passage55, the connection flow passage52, and the pressurizing flow passage51and, therefore, the internal pressure of the second chamber68increases. The pressure sensor49may detect the internal pressure of the connection flow passage52, the pressurizing flow passage51, and the second chamber68at this time. The control portion19may control the driving of the pressurizing portion47based on the detection result of the pressure sensor49.

Structure of Liquid Container24

Next, with reference toFIGS.3and4, a structure of the liquid container24will now be explained.

As illustrated inFIGS.3and4, for example, the liquid container24is a cartridge that has a first end wall142, a top wall143, a bottom wall144, a first sidewall145, a second sidewall146, and a second end wall147. When the liquid container24starts being inserted in the process of being attached to the liquid ejecting apparatus11, the first end wall142is the first to be inserted.

As illustrated inFIG.3, an identification portion430for identifying the type of the liquid container24may be provided on the bottom wall144of the liquid container24. The identification portion430may be, for example, a plurality of protrusions arranged in the width direction.

The liquid container24may have a positioning hole448in the bottom wall144. The positioning hole448may be a recess formed in the bottom wall144. The liquid container24may have the pouring outlet portion30having its opening in the bottom wall144. The liquid contained in the liquid container24flows out of the liquid container24via the pouring outlet portion30. The liquid container24may have a release portion241protruding down from the bottom wall144. The release portion241, the positioning hole448, the pouring outlet portion30may be arranged in this order as viewed from the second end wall147toward the first end wall142.

As illustrated inFIG.3, the liquid container24may include a circuit board chip150provided at a corner-cut portion, meaning that a corner where the bottom wall144and the first end wall142were supposed to meet with each other is missing. The circuit board chip150may include connection terminals521and a storage medium525. The storage medium525may store information about the liquid container24, for example, information about the liquid contained in the liquid container24.

The liquid container24may have two guided portions447extending along the Y axis in the first sidewall145and the second sidewall146respectively. In each of the sidewalls145and146, the guided portion447may include a first guided portion447aand a second guided portion447bformed at different positions in height. The first guided portion447amay be a groove extending along the bottom wall144. The second guided portion447bis located above the first guided portion447a. The second guided portion447bis shorter than the first guided portion447ain the direction along the Y axis. The second guided portion447bmay be located near the circuit board chip150.

As illustrated inFIG.4, the liquid container24has an engagement portion497in the second end wall147. The engagement portion497is, for example, a recess formed in the second end wall147and located over the release portion241. The engagement portion497may be located at the center of the second end wall147in the width direction.

Structure of Attachment Portion28

As illustrated inFIG.5, the attachment portion28includes a frame80like a box, a supporting member90, a pivot91, and the first inlet portion60. The supporting member90, the pivot91, and the first inlet portion60are disposed inside the frame80. The liquid container24is inserted into the frame80through the insertion opening28oand moves toward the rear of the frame80. The direction of this movement of the liquid container24, that is, the direction of insertion thereof into the attachment portion28, is along the Y axis.

The supporting member90extends along a linear guiding path82(indicated by an open arrow inFIG.5) intersecting with a vertical line (Z axis). The guiding path82extends in the moving direction (along the Y axis). The supporting member90has a head-end region and a base-end region. The start end of the guiding path82is located at the head-end region. The termination end of the guiding path82is located at the base-end region. The base-end region of the supporting member90and the pivot91are located at the inner rear of the frame80, namely, at a position distant from the insertion opening28o. The supporting member90may have a bottom plate90aand two side ribs90b. The two side ribs90bare arranged at the respective two ends of the bottom plate90ain the width direction.

The pivot91is disposed at the base-end region of the supporting member90. The pivot91has its axial line intersecting with both of the vertical line (Z axis) and the guiding path82(Y axis). The axial line of the pivot91extends along the X axis. The supporting member90is configured to rotate on the pivot91between a guiding position, which is a position for guiding the liquid container24along the guiding path82(indicated by alternate long and short dash lines inFIG.5), and a connection position, which is a position for connection of the liquid container24to the first inlet portion60(indicated by alternate long and two short dash lines inFIG.5).

The first inlet portion60is disposed below the supporting member90. The first inlet portion60becomes connected to the liquid container24when the supporting member90comes to the connection position. The first inlet portion60may be in a tilted position with respect to the guiding path82(which is horizontal). More specifically, the first inlet portion60may be tilted such that its head end (upper end) is located closer to the insertion opening28othan its base end (lower end) is. For example, the axial line of the first inlet portion60may be inclined with respect to the vertical line (Z axis) within an angular range of 0° to 15°.

The liquid container24may include one or more guiding portions247configured to guide the movement of the liquid container24. For example, the guiding portions247may be a pair of guide rails provided on the side ribs90bmaking up a pair. Alternatively, a single guide rail may be provided on the bottom plate90a.

The guiding portion247may include a first guiding portion247aand a second guiding portion247bdisposed such that the first guided portion447aand the second guided portion447bare configured to come into engagement therewith respectively. The guiding portion247a,247bmay be, for example, a protruding portion extending in the length direction of the supporting member90. The second guiding portion247bis located above the first guiding portion247a. The second guiding portion247bis shorter than the first guiding portion247ain the length direction. The second guiding portion247bmay be located closer to the pivot91than the first guiding portion247ais. The first guiding portion247amay be disposed at a position corresponding to the first inlet portion60in the direction of the movement of the liquid container24.

The attachment portion28may include a first urging member83configured to urge the supporting member90from the connection position toward the guiding position. The first urging member83is, for example, a coil spring. In an initial state in which there is no liquid container24in the attachment portion28, the supporting member90is located at the guiding position by being urged by the first urging member83.

As illustrated inFIG.6, the attachment portion28may have a positioning protruding portion248protruding upward near the first inlet portion60. The liquid container24is positioned by the mating engagement of the positioning hole448with the positioning protruding portion248. The positioning protruding portion248may be inclined at the same angle as that of the first inlet portion60. The bottom plate90a(seeFIG.5) has a cutout portion at a region over the positioning protruding portion248and the first inlet portion60.

As illustrated inFIG.6, the attachment portion28may include a latching lever84disposed in such a way as to face the head end of the supporting member90. The latching lever84, the positioning protruding portion248, and the first inlet portion60may be arranged in this order along the Y axis. The latching lever84may have a base end (lower end) and a head end (upper end). The base end may be fixed to the frame80. The attachment portion28may include a second urging member85configured to urge the head end of the latching lever84toward the supporting member90.

The latching lever84is disposed in such a way as to latch onto the liquid container24supported by the supporting member90when the supporting member90is located at the connection position. The latching lever84may have a first sloped surface86extending obliquely downward from the head end and a second sloped surface87extending obliquely downward from the lower end of the first sloped surface86. The first sloped surface86and the second sloped surface87form a protrusion protruding toward the supporting member90.

The first sloped surface86engages with the liquid container24when the supporting member90rotates along a rotation path from the guiding position (position illustrated inFIG.6) toward the connection position (position illustrated inFIG.7). The second sloped surface87engages with the liquid container24when the supporting member90is located at the connection position and when the supporting member90rotates from the connection position toward the guiding position.

Next, with reference toFIGS.6and7, a structure of the outlet valve31of the pouring outlet portion30and a structure of the inlet valve61of the first inlet portion60will now be explained.

As illustrated inFIG.6, the outlet valve31of the liquid container24includes a valve body31aand an elastic member31b. The elastic member31burges the valve body31aoutward (downward inFIG.6). The outlet valve31closes when the valve body31aurged by the elastic member31bis located at a valve-closing position closer to the outside as illustrated inFIG.6. The outlet valve31opens when the valve body31ais pushed inward (upward inFIG.7) against an urging force applied by the elastic member31bas illustrated inFIG.7.

As illustrated inFIG.6, the inlet valve61of the first inlet portion60includes a valve body61aand an elastic member61b. The elastic member61burges the valve body61aoutward (upward inFIG.6). The inlet valve61closes when the valve body61aurged by the elastic member61bis located at a valve-closing position closer to the outside as illustrated inFIG.6. The inlet valve61opens when the valve body61ais pushed inward (downward inFIG.7) against an urging force applied by the elastic member61bas illustrated inFIG.7.

As illustrated inFIG.6, the valve body31aof the outlet valve31has a protruding portion31cat its tip. As illustrated inFIG.7, in a state in which the liquid container24is attached to the attachment portion28, the protruding portion31cof the valve body31apushes the valve body61aof the inlet valve61inward (downward inFIG.7). The valve body31aof the outlet valve31is pushed upward at this time. As a result, in a state in which the liquid container24is attached to the attachment portion28, the pouring outlet portion30and the first inlet portion60are connected to each other, with both of the outlet valve31and the inlet valve61being opened.

Operation of Supply Unit25

Next, operation performed when the liquid container24is attached to the supply unit25will now be explained.

As illustrated inFIG.5, the liquid container24is inserted into the frame80through the insertion opening28o. After the first guided portions447aof the liquid container24come into engagement with the first guiding portions247ainside the frame80, the liquid container24moves horizontally along the guiding path82extending along the Y axis by being guided by the first guiding portions247a. The movement of the liquid container24in the width direction in this process is restricted by the two first guiding portions247aarranged in the width direction. The upward movement of the liquid container24while being guided along the path is restricted by the frame80. The downward movement of the liquid container24while being guided along the path is restricted by a lock lever92(seeFIG.7).

When the liquid container24comes to a position near the termination end of the guiding path82, the second guided portions447bcome into engagement with the second guiding portions247b. An electric coupling portion (not illustrated) may be disposed between the first guiding portions247aand the second guiding portions247bin the vertical direction Z. In this case, the connection terminals521are positioned appropriately toward the electric coupling portion in the vertical direction Z. The liquid container24may be positioned in the width direction by an identification shape portion disposed near the electric coupling portion.

The connection terminals521are coupled to the electric coupling portion when the liquid container24arrives at the termination end of the guiding path82. This makes it possible to perform data communication between the circuit board chip150and the control portion19(seeFIG.1). The second end wall147of the liquid container24is either exposed to the outside of the frame80or is located at a position where it is operable from the outside of the frame80at this time.

Next, the user pushes the rear end (the right end inFIG.5) of the liquid container24downward while pushing the liquid container24in the inserting direction against an urging force applied by a fourth urging member (not illustrated). Because of this pushing, the supporting member90rotates in a clockwise direction inFIG.5around the pivot91against an urging force applied by the first urging member83. In the process of rotation of the liquid container24, first, the positioning protruding portion248becomes inserted in the positioning hole448(seeFIGS.6and7), and, next, the pouring outlet portion30becomes connected to the first inlet portion60.

Due to expansion and contraction of an urging spring (not illustrated), a small change in position of the liquid container24along the Y axis is allowed while keeping the coupling of the connection terminals521to the electric coupling portion (not illustrated). The positioning protruding portion248is disposed near the first inlet portion60, and the positioning protruding portion248is inclined at the same angle as that of the first inlet portion60; therefore, the pouring outlet portion30is guided toward the first inlet portion60properly.

In the process of rotation of the supporting member90to the connection position, the liquid container24supported by the supporting member90comes into contact with the first sloped surface86of the latching lever84. The upper end of the latching lever84pushed by the liquid container24changes its position outward (rightward inFIG.5) in such a way as to get out of the way of rotation of the supporting member90against an urging force applied by the second urging member85. When the protrusion of the latching lever84comes into engagement with the engagement portion497of the liquid container24, the supporting member90stops and stays at the connection position due to the urging force applied by the second urging member85. The attachment of the liquid container24is completed in this way.

As illustrated inFIG.7, the pouring outlet portion30becomes connected to the first inlet portion60when the attachment of the liquid container24is completed. Both of the outlet valve31and the inlet valve61are in an open state at this time. Since the liquid container24is disposed over the first inlet portion60, the liquid contained in the liquid container24flows into the first reservoir portion33via the first inlet portion60due to a hydraulic head difference.

Next, operation performed when the liquid container24is detached from the supply unit25will now be explained.

To detach the liquid container24from the attachment portion28, the user pulls the rear end (the right end inFIG.5) of the liquid container24upward against the urging force applied by the second urging member85. In this process, since the engagement portion497is in engagement with the second sloped surface87, the supporting member90rotates smoothly together with the liquid container24. When the protrusion of the latching lever84becomes disengaged from the engagement portion497, the supporting member90rotates from the connection position to the guiding position around the pivot91due to the urging force applied by the first urging member83.

In the process of rotation of the supporting member90from the connection position to the guiding position, the pouring outlet portion30becomes disconnected from the first inlet portion60, and the positioning protruding portion248gets out of the positioning hole448. In the process of disconnection of the pouring outlet portion30from the first inlet portion60, both of the outlet valve31and the inlet valve61become closed. Upon the arrival of the supporting member90at the guiding position, the liquid container24is pushed toward the start end of the guiding path82due to the urging force applied by the fourth urging member (not illustrated). Since the liquid container24is guided by the first guiding portions247aand the second guiding portions247b, the connection terminals521are uncoupled from the electric coupling portion (not illustrated) of the attachment portion28quickly without being twisted. At the same time, the release portion241is released from a first arm (not illustrated), and the lock lever92returns to a lock position due to an urging force applied by the third urging member (not illustrated).

The user thereafter draws the liquid container24toward the outside of the frame80. The liquid container24that is being drawn outward is guided by the first guiding portions247a. Since the rotation of the supporting member90is restricted by the lock lever92, the liquid container24moves horizontally along the Y axis without any contact with the first inlet portion60.

Detailed Structure of Tank Unit26

Next, with reference toFIGS.8and10, a detailed structure of the tank unit26will now be explained.

As illustrated inFIGS.8and10, the tank unit26includes the first inlet portion60, the first chamber62, and the second chamber68. The first chamber62and the second chamber68are formed as chambers by pasting films F1and F2to the sides of the synthetic-resin frame constituting the reservoir portions of the tank unit26.

The first inlet portion60is configured to be connected to the liquid container24(seeFIG.2) attached to the attachment portion28. The first inlet portion60becomes connected to the pouring outlet portion30(seeFIG.2) of the liquid container24when the liquid container24is attached to the attachment portion28. In the attached state, the liquid supplied from the liquid container24flows into the first chamber62via the first inlet portion60.

As illustrated inFIGS.8and10, the first inlet portion60is connected to the first chamber62via an opening portion603at some midpoint in the vertical direction Z of the first chamber62. The first inlet portion60has an inlet passage601serving as a flow passage for liquid flowing in from the liquid container24. The inlet passage601may extend obliquely downward with respect to the vertical direction Z as illustrated inFIGS.8and10. Alternatively, the inlet passage601may extend in the vertical direction Z. The first inlet portion60has the opening portion603at the downstream end of the inlet passage601in the direction in which the liquid flows. In the example illustrated inFIGS.8and10, the first inlet portion60has an inlet60a, via which the liquid flows in from the liquid container24(seeFIG.2) attached to the attachment portion28, and the first inlet portion60is connected to the first chamber62via the opening portion603formed at an opposite end located opposite of the inlet60a. As described here, the first inlet portion60is connected to the first chamber62via the opening portion603at the downstream end of the inlet passage601passing inside through the first inlet portion60in the direction in which the liquid flows. The opening plane of the opening portion603may be inclined with respect to a horizontal plane as illustrated inFIGS.8and10. Alternatively, the opening plane of the opening portion603may be a horizontal plane.

The first inlet portion60may have a regulating portion602for partitioning off the inlet passage601from the first chamber62. The regulating portion602serves as a partition plate between the inlet passage601and the first chamber62. The regulating portion602has a function of regulating, to the standard level position SH, the first liquid surface66indicating the level of the liquid stored in the first chamber62.

As illustrated inFIGS.8and10, the tank unit26includes the outlet portion74and the second inlet portion75. The outlet portion74is in communication with the second chamber68. The liquid stored in the second chamber68is configured to flow out via the outlet portion74toward the liquid ejecting head23(seeFIG.2). The outlet portion74is connected to one end of the supply flow passage37, which is in communication with the liquid ejecting head23(seeFIG.2).

The second inlet portion75is in communication with the first chamber62. The liquid collected from the liquid ejecting head23is configured to flow in via the second inlet portion75. The second inlet portion75is in communication with one end of the collection flow passage39, which is in communication with the liquid ejecting head23.

As illustrated inFIG.8, the tank unit26includes a first connection portion76to which the opening-to-atmosphere path50is connected. The opening-to-atmosphere path50(seeFIG.2) is, for example, a tube. One end of this tube is connected to the first connection portion76. The first connection portion76is, for example, a conduit connector portion to which a conduit such as a tube can be connected. The tank unit26includes an air flow passage78that is in communication with the first connection portion76. The air flow passage78is in communication with the inside of the first chamber62via the first opening-to-atmosphere portion64illustrated inFIG.10. More specifically, the first reservoir portion33has an opening-to-atmosphere port33aillustrated inFIG.10. The first chamber62is in communication with the air flow passage78illustrated inFIG.8via the opening-to-atmosphere port33aand the first opening-to-atmosphere portion64.

The first chamber62of the tank unit26is in communication with the opening-to-atmosphere path50(seeFIG.2) via the first opening-to-atmosphere portion64, the air flow passage78, and the first connection portion76. Therefore, a first vapor-phase portion62G inside the first chamber62is open to atmosphere. As described earlier, when the first opening-to-atmosphere portion64includes a vapor-liquid separator film, it is possible to open the inside of the first chamber62to atmosphere while preventing the liquid stored in the first chamber62from leaking out.

As illustrated inFIG.8, the tank unit26includes a second connection portion77that is in communication with the second chamber68. The second connection portion77is in communication with the second opening-to-atmosphere portion69. The second connection portion77is connected to the pressurizing flow passage51. The pressurizing flow passage51is, for example, a tube. One end of this tube is connected to the second connection portion77. The second connection portion77is in communication with a second air flow passage79.

The second air flow passage79is in communication with the second chamber68via the second opening-to-atmosphere portion69. The second chamber68is in communication with the pressurizing flow passage51(seeFIG.2) via the second opening-to-atmosphere portion69, the second air flow passage79, and the second connection portion77. The pressurization of the second chamber68is performed by supplying pressurized air from the pressurizing portion47into the second chamber68through the pressurizing flow passage51, the second connection portion77, the second air flow passage79, and the second opening-to-atmosphere portion69. More specifically, the second reservoir portion35has an opening-to-atmosphere port35aillustrated inFIG.10. The second chamber68is in communication with the air flow passage79illustrated inFIG.8via the opening-to-atmosphere port35aand the second opening-to-atmosphere portion69.

When the time for cleaning has come, the control portion19drives the pressurizing portion47to supply pressurized air therefrom into the second chamber68, thereby applying pressure to the liquid stored in the second chamber68. As a result, the liquid is forced out through the nozzles22of the liquid ejecting head23. The cleaning of the liquid ejecting head23is performed in this way. The cleaning prevents the nozzles22of the liquid ejecting head23from becoming clogged or unclogs the clogged nozzles, etc.

When the second opening-to-atmosphere portion69includes a vapor-liquid separator film, it is possible to supply pressurized air into the second chamber68while preventing the liquid stored in the second chamber68from leaking out. Pressurized air may be supplied from the pressurizing portion47into the first chamber62through the opening-to-atmosphere path50.

As illustrated inFIG.10, the opening portion603may be located below the center HL inside the first chamber62in the vertical direction Z. InFIG.10, a region where the first chamber62exists in the vertical direction Z (Z-axis direction) is defined as a reservoir chamber area TA. The first inlet portion60is connected to the first chamber62at some midpoint in height within the reservoir chamber area TA in the vertical direction Z. The opening portion603is provided at the lower end of the inlet passage601of the first inlet portion60. The first inlet portion60is connected to the first chamber62via the opening portion603at some midpoint in height within the reservoir chamber area TA in the vertical direction Z. The regulating portion602, which is a part of members forming the inlet passage601, serves as a partition between the inlet passage601and the first chamber62.

A lower end604of the regulating portion602regulates the liquid-level position of the first liquid surface66to the standard level position SH. That is, the position of the lower end604of the regulating portion602is set such that the first liquid surface66will be at the standard level position SH. The first liquid surface66rises in level when the liquid flows in from the liquid container24. Then, the first liquid surface66rising in level reaches the lower end604of the regulating portion602. Upon the reaching thereof, the supply of the liquid from the liquid container24via the first inlet portion60stops.

The inside of the first chamber62is divided into a first liquid-phase portion62L, which is a liquid-phase portion where liquid is stored, and the first vapor-phase portion62G, which is a vapor-phase portion where air is present, with the first liquid surface66being the boundary therebetween. That is, the first chamber62is divided into the first liquid-phase portion62L, which is a region located below the first liquid surface66, and the first vapor-phase portion62G, which is a region located above the first liquid surface66.

The inside of the second chamber68is divided into a second liquid-phase portion68L, which is a liquid-phase portion where liquid is stored, and a second vapor-phase portion68G, which is a vapor-phase portion where air is present, with the second liquid surface70being the boundary therebetween. That is, the second chamber68is divided into the second liquid-phase portion68L, which is a region located below the second liquid surface70, and the second vapor-phase portion68G, which is a region located above the second liquid surface70. The upper portion of a region including the inside of the inlet passage601is formed as an inlet vapor-phase portion60G, which is a vapor-phase portion where air is present, with a liquid surface67being the boundary therebetween. The liquid-level position of the liquid surface67is almost the same as that of the first liquid surface66.

As illustrated inFIGS.8and10, the liquid surface detecting portion63includes a first detecting portion63a, a second detecting portion63b, and a third detecting portion63c. The first detecting portion63aillustrated inFIG.10detects the first liquid surface66that is at the standard level position SH. The control portion19determines that the liquid-level position of the first liquid surface66is normal when the first liquid surface66that is at the standard level position SH. When the first detecting portion63ais no longer able to detect the first liquid surface66due to a deviation of the first liquid surface66from the standard level position SH beyond a tolerable range, the control portion19may adjust the first liquid surface66to a liquid-level position detectable by the first detecting portion63a. For example, the control portion19may adjust the liquid-level position of the first liquid surface66to the standard level position SH by controlling the internal pressure of the first chamber62through the first opening-to-atmosphere portion64by controlling the pressurizing portion47and the switching mechanism48.

The second detecting portion63billustrated inFIG.8detects the first liquid surface66(seeFIG.10) when the amount of the liquid left in the first chamber62is less than an END threshold. The second detecting portion63bdetects that the amount of the liquid left in the first chamber62has reached “END”. When the amount of the liquid left has reached “END”, the control portion19causes the display portion15ato display a message, etc. that prompts the user to replace this liquid container24with another one.

The third detecting portion63cillustrated inFIG.8detects the first liquid surface66(seeFIG.10) when the first liquid surface66is at a full level position in excess of the standard level position SH. By detecting the first liquid surface66that is at the full level position, the third detecting portion63cprevents the leakage of the liquid through the nozzles22of the liquid ejecting head23. Moreover, by detecting the first liquid surface66that is that is close to an overflow liquid level, the third detecting portion63cprevents the leakage of the liquid stored in the first chamber62through the opening-to-atmosphere port33a. The full level position is set to be a liquid level which is before reaching the overflow liquid level and at which the leakage of the liquid through the nozzles22does not occur due to a hydraulic head difference between the nozzles22of the liquid ejecting head23and the first liquid surface66.

As illustrated inFIGS.8and10, when viewed in the vertical direction Z, the first chamber62and the second chamber68overlap at least partially. In the example illustrated inFIGS.8and10, the first chamber62has an overhang portion protruding in the horizontal direction, and the second chamber68has an underlying portion protruding in the horizontal direction, and when viewed in the vertical direction Z, the first chamber62and the second chamber68are arranged in such a layout that the overhang portion and the underlying portion overlap.

The first chamber62is the detection-target reservoir chamber configured such that the amount of liquid left in the tank unit26is detected by the liquid surface detecting portion63. For the purpose of reducing variation in END detection precision when the amount of the liquid left in the first chamber62has reached “END”, it is preferable if the percentage of change in liquid level per unit amount of liquid is large when the amount of the liquid left in the first chamber62has become small. Therefore, it is preferable if the first chamber62has a shape the capacity of the lower portion of which is smaller than the capacity of the upper portion thereof. On the other hand, for the purpose of enabling the first chamber62to accommodate liquid forced out by thermal expansion at the vapor-phase portion inside the liquid container24due to a change in temperature, it is preferable if the first chamber62has a large capacity. For these reasons, preferably, the first chamber62should have a shape that has a large capacity at its upper portion though the capacity of its lower portion is small, as illustrated inFIGS.8and10. In the example illustrated inFIGS.8and10, the first chamber62has an overhanging shape whose upper portion protrudes in the horizontal direction in comparison with its lower portion.

Since there is no need to detect the second liquid surface70, the second chamber68can be configured to have a shape that has a larger capacity at its lower portion than its upper portion as illustrated inFIGS.8and10. In the example illustrated inFIGS.8and10, the second chamber68has a shape whose lower portion protrudes in the horizontal direction in comparison with its upper portion.

As illustrated inFIGS.8and10, when viewed in the vertical direction Z, the first chamber33and the second chamber35are arranged in such a manner that the upper portion of the first chamber33protruding in the horizontal direction overhangs the lower portion of the second chamber35protruding in the horizontal direction to form an overlap. Therefore, the first chamber62and the second chamber68are arranged efficiently inside a substantially rectangular accommodation space.

As illustrated inFIG.10, the tank unit26may further include a filter100provided between the second chamber68and the outlet portion74and configured to trap foreign objects contained in the liquid. The term “foreign objects” as used herein include air bubbles, fine dust particles, etc. contained in the liquid. The filter100may be provided also between the first chamber62and the second inlet portion75. In this case, a single common filter may be provided as the filter100, or, alternatively, individual filters may be provided separately.

As illustrated inFIG.9, the first chamber62may have a cover portion88inside. The cover portion88may be provided vertically over the second inlet portion75formed in a lower surface inside the first chamber62. As illustrated inFIG.9, a communication opening75athrough which the second inlet portion75is in communication with the first chamber62is formed in the lower surface (inner bottom surface) of the first chamber62. The cover portion88is provided vertically over the communication opening75a. The cover portion88has a shape like an eave for covering the communication opening75a. When a returning flow of liquid enters from the second inlet portion75, in some instances the liquid gushes out with great energy from the communication opening75ainto the first chamber62. Even in this case, the liquid gushing out hits against the cover portion88, and the energy of the gushing flow of the liquid is therefore abated. This prevents the liquid flowing in through the communication opening75afrom gushing up to a position near the opening-to-atmosphere port33a.

As illustrated inFIG.10, the on-off valve36includes a one-way valve that tolerates flow of the liquid from the first chamber62toward the second chamber68and does not tolerate flow of the liquid from the second chamber68toward the first chamber62. In the example illustrated inFIG.10, a plurality of (for example, two) on-off valves36is provided. A detailed structure of the one-way valve of the on-off valve36will be described later.

As illustrated inFIG.10, the opening-to-atmosphere portion64includes a vapor-liquid separator film. The vapor-liquid separator film is, for example, a breathable film. The vapor-liquid separator film allows air to pass and does not allow liquid to pass. The liquid-repellent performance of a surface of the breathable film is set, with water supposed. The breathable film has lower liquid repellency when the liquid is ink than when the liquid is water, and permeation is thus easier when the liquid is ink than when the liquid is water. Therefore, a liquid-repellent agent or an antifoam agent may be applied to the breathable film to make the permeation of ink harder.

Liquid Container24

As illustrated inFIG.10, the first chamber62necessitates the vapor-phase portion62G. Since the inside of the liquid container24is a hermetically-closed space, in some instances liquid is forced out of the liquid container24into the first chamber62when thermal expansion of internal air occurs due to a change in temperature. Therefore, the vapor-phase portion62G is set so as to ensure sufficient capacity that is large enough for accommodating the liquid even when the maximum possible amount of the liquid is forced out of the liquid container24by the thermal expansion of the internal air of the liquid container24.

As illustrated inFIG.1, the capacity of the liquid container24differs depending on the type of the liquid (for example, ink color). The liquid container24for black ink is wider than that for color ink. Similarly to the liquid container24, the first reservoir portion33for black ink is wider than that for color ink. Therefore, the vapor-phase portion62G of the first chamber62for black ink, as can be read fromFIG.1, is larger than that for color ink. Given the same percentage of use (percentage of supply) of the liquid (e.g., ink), the vapor-phase portion for black ink is larger than that for color ink, and an amount of the liquid forced out when the thermal expansion of the air of the vapor-phase portion for black ink occurs is larger than that for color ink. In the example of the present embodiment, the vapor-phase portion62G of the first chamber62for black ink is larger than that for color ink. Therefore, even when the liquid is forced out of the liquid container24by the thermal expansion of the internal air of the liquid container24due to a change in temperature, the first chamber62is able to accommodate the liquid flowing in, without causing any overflow.

As illustrated inFIG.10, the first inlet portion60is inclined at a predetermined angle. The predetermined angle is a predetermined angular value within a range of, for example, 1° to 15°. Therefore, the liquid container24is attached with inclination at a predetermined angle with respect to the vertical direction Z, similarly to the inclination of the first inlet portion60. Since the liquid container24is attached with inclination at the predetermined angle, it is possible to use up the liquid almost without a significant leftover in the liquid container24.

Detection of Tilt of Tank Unit26

As illustrated inFIG.12, the tank unit26further includes a tilt detecting portion98that detects the tilt of the tank unit26itself. The tilt detecting portion98is supported in a state of being fixed to a frame89that supports the tank unit26. The tilt detecting portion98outputs a detection signal obtained by detecting the tilt of the tank unit26to the control portion19.

Based on the detection signal supplied from the tilt detecting portion98, the control portion19determines whether the angle of the tilt of the tank unit26exceeds an angular threshold or not. When the angle of the tilt of the tank unit26exceeds the angular threshold, the control portion19prohibits the liquid ejecting apparatus11from performing print operation (liquid ejecting operation). In addition, the control portion19causes the display portion15ato display a message, etc. that prompts the user to adjust the tilt of the liquid ejecting apparatus11. One of the causes of excessive inflow of the liquid from the liquid container24into the first reservoir portion33is a tilt exceeding the tolerance of the tank unit26. Therefore, the control portion19may cause the display portion15ato display a message, etc. that prompts the user to adjust the tilt of the liquid ejecting apparatus11when the angle of the tilt of the tank unit26detected by the tilt detecting portion98exceeds a predetermined angular threshold. When the angle of the tilt of the tank unit26detected by the tilt detecting portion98exceeds a predetermined angular threshold, the control portion19may put the liquid ejecting apparatus11into a state in which printing cannot be started until the excessive tilt is corrected. In this case, print operation of the liquid ejecting apparatus11based on a print instruction given by the user is started when the angle of the tilt detected by the tilt detecting portion98becomes less than the angular threshold as a result of the corrective adjustment of the tilt of the liquid ejecting apparatus11by the user.

As illustrated inFIGS.11and12, in the tank unit26, plural sets each made up of the first inlet portion60and the positioning protruding portion248are arranged adjacently along the X axis. Plural liquid surface detecting portions63are arranged adjacently along the X axis at respective opposite adjacent positions that are the opposite of the respective positions of the plurality of positioning protruding portions248in the direction along the Y axis with respect to the plurality of first inlet portions60. Respective terminal portions63dof the plurality of liquid surface detecting portions63are exposed at the upper surface of the attachment portion28as viewed from above. The terminal portions63dare electrically coupled to the control portion19via non-illustrated signal lines.

The tank unit26includes absorption members93and94disposed under the first reservoir portion33. The absorption member93,94has a function of absorbing the liquid such as ink that leaks during the attachment and detachment of the liquid container24. The absorption members93and94are disposed throughout an area where they are able to absorb the liquid having spattered from or having trickled down the first inlet portion60. The liquid spattering from the first inlet portion60or the liquid running down along the side surface of the first inlet portion60are guided to the first absorption member93.

The first absorption member93is supported on the frame89in upright position along the vertical direction Z near a position that is right under the first inlet portion60. The second absorption member94is provided horizontally on the frame89in a state in which a part of the second absorption member94is in contact with the base end portion of the first absorption member93. As illustrated inFIG.11, the two absorption members93and94form a shape like a letter L in side view. The second absorption member94is disposed almost throughout the entire area right under the first reservoir portion33and the second chamber68. Therefore, even in case of the leakage of the liquid from the first reservoir portion33or the second chamber68or in case of the running of the liquid down along the outer wall surface thereof, the liquid is absorbed by the second absorption member94.

Structure for Preventing Leakage of Liquid from First Inlet Portion60

Next, with reference toFIGS.13and14, a structure for preventing the leakage of liquid from the inlet60aof the first inlet portion60and for collecting the liquid that has leaked notwithstanding the existence of this leakage prevention structure will now be explained. The tank unit26has a liquid leakage prevention structure near and under the first inlet portion60.

As illustrated inFIG.13, the liquid leakage prevention structure is made up of a liquid spattering prevention wall605, which is provided on the first inlet portion60, and a liquid collection structure including a guiding groove606, through which the liquid that has spattered notwithstanding the existence of the liquid spattering prevention wall605can be collected.

First, with reference toFIGS.6,7, and14, a phenomenon of the spattering of liquid from the inlet60athat occurs during the detachment of the liquid container24will now be explained. A part of liquid that has flowed into the first inlet portion60through the pouring outlet portion30is left in a space60sthat is a part of the flow passage inside the first inlet portion60. In the process of the detachment of the liquid container24from the attachment portion28, the pressure of the space60sinside the first inlet portion60becomes negative due to volume expansion. More specifically, the valve body61amoves up toward the inlet60awhile the inlet60aremains closed by the protruding portion31c. The inlet valve61becomes closed because of the upward movement of the valve body61a. The inlet60ais still closed by the protruding portion31c(seeFIG.7) even after the closing of the inlet valve61. Therefore, the space60sinside the first inlet portion60(seeFIG.14) is temporarily a closed space. After the forming of this closed space60s, in the process of further upward movement of the protruding portion31cuntil being pulled out from the inlet60a, the closed space60sis depressurized due to the expansion of the internal air, resulting in negative pressure. The negative pressure acts as a force for sucking up the liquid left in the space60stoward the inlet60a. Therefore, there is a possibility that the liquid might spatter from the inlet60awhen the liquid container24is detached from the attachment portion28.

The first inlet portion60has the liquid spattering prevention wall605, which is mounted on the head end portion on the inlet (60a) side to cover its periphery, with the inlet60aonly being opened. The liquid spattering prevention wall605has an annular wall portion covering the periphery of the inlet60a.

As illustrated inFIG.13, the liquid spattering prevention wall605is mounted on the head end portion of the first inlet portion60in a surrounding manner, with the inlet60abeing opened. Because of the existence of the liquid spattering prevention wall605, the spattering of the liquid from the inlet60ais considerably suppressed. However, it is impossible to prevent the spattering of the liquid from the inlet60aperfectly.

For this reason, the tank unit26has a liquid collection structure for collecting the liquid that has spattered from the inlet60a. The liquid collection structure includes the annular guiding groove606illustrated inFIG.13, a guiding recessed portion96, a guiding hole96aillustrated inFIG.14, a guide portion97, and the first absorption member93.

The liquid collection structure includes the guiding groove606at an area where it can catch the liquid having spattered from the inlet60aand having dropped around the inlet60a. The first inlet portion60has a columnar protruding portion607having the inlet60aat its mouse. The guiding groove606is formed as an annular grooved path in the upper surface of a truncated-cone portion disposed at the base of the protruding portion607.

In a side view from the direction along the X axis inFIG.14, the surface in which the guiding groove606is formed is inclined at a predetermined angle with respect to a horizontal plane. The predetermined angle is, for example, substantially equal to the angle of inclination of the axial line CL of the first inlet portion60with respect to the vertical direction Z. The annular guiding groove606guides the liquid toward a lower position.

As illustrated inFIG.14, the guiding recessed portion96for guiding the liquid from the lower end of the guiding groove606downward by causing the liquid to run down along the side surface is formed between the first inlet portion60and the positioning protruding portion248. As illustrated inFIG.13, the guiding recessed portion96is formed by spaces partitioned by three wall plate portions96barranged at intervals along the X axis between the first inlet portion60and the positioning protruding portion248. The guiding groove606is open at its lower end toward the guiding recessed portion96in such a way as to be able to guide the liquid to the guiding recessed portion96. The liquid guided along the annular guiding groove606after having spattered from the inlet60ais guided to the guiding recessed portion96. As illustrated inFIG.14, the liquid having been guided along the annular guiding groove606to the lower side flows through the guiding recessed portion96to be guided downward.

As illustrated inFIG.14, there is the guiding hole96aat the bottom of the guiding recessed portion96. The liquid having passed through the guiding hole96aruns down along the side surface or drips. The first absorption member93is disposed at a position near the lower end of the guiding path of the liquid running down along the side surface or dripping. The guide portion97that is partially embedded in the upper portion of the first absorption member93is disposed obliquely at a position near the lower end of the guiding path of the liquid. The liquid having been guided down along the guiding path of the liquid is guided by the guide portion97to the first absorption member93and is then absorbed by the first absorption member93. The first absorption member93is located at an inner position enclosed by the frame89. Therefore, the liquid having been absorbed by the first absorption member93never leaks to the outside of the frame89.

Structure of On-Off Valve36

Next, with reference toFIGS.15to18, a structure of the on-off valve36will now be explained. The on-off valve36is a differential pressure regulating valve configured to be opened and closed by a hydraulic head difference between the first liquid surface66of the first chamber62and the second liquid surface70of the second chamber68. The on-off valve36includes a valve body101.

For example, an umbrella valve, which is an umbrella-type valve body, has been sometimes used in related art as the valve body of this kind of differential pressure regulating valve configured to be opened and closed by a hydraulic head difference. However, if an umbrella valve is used, there is a possibility that minute leakage of liquid might occur because it is difficult to ensure required close contact pressure with a valve seat. Minute leakage of this kind could cause variation in the level of the second liquid surface70. This means variation in a hydraulic head difference, and has an influence on the size of a liquid droplet ejected from the liquid ejecting head23, resulting in affecting print quality. Therefore, it is demanded that an amount of minute leakage of this kind should be as small as possible, or, ideally, zero. In view of this, in the present embodiment, the valve body101that has a shape illustrated inFIGS.16and17is used as the valve body of the on-off valve36. One surface (bottom surface) of the outlet flow passage34is made of a film F3illustrated inFIG.17.

As illustrated inFIGS.16and17, the valve body101includes a shaft portion102and a valve portion103. The shaft portion102has a slip stopper portion104bulged relatively in a radial direction at some midpoint in its axial direction. The shaft portion102extends almost perpendicularly from the center portion of the valve portion103having a shape like a disc.

The valve portion103includes a valve plate portion103a, which has a shape like a disc with enhanced rigidity achieved by securing a predetermined thickness, a rip portion105, which is an annular continuous seal protruding from the shaft-portion-side (102) surface of the valve plate portion103a, and an annular flange portion106, which extends outward in the radial direction from the periphery of the valve plate portion103a. The flange portion106is thinner than, and is more flexible than, the valve plate portion103a. The thickness of the flange portion106may decrease as it goes toward the outer rim.

As illustrated inFIG.17, a plurality of valve holes332is formed in a partitioning wall portion331between the first chamber62and the outlet flow passage34at positions where the valve bodies101are mounted. The plurality of valve holes332provides communication between the first chamber62and the outlet flow passage34. The partitioning wall portion331has a recessed surface as a surface facing the outlet flow passage34at the region where the plurality of valve holes332is formed. The bottom of the recessed surface serves as a valve seat333. InFIG.17, the valve body101is in an open state, in which the valve portion103is not in contact with the valve seat333. The valve body101moves in its shaft direction to open and close the plurality of valve holes332due to a difference between hydraulic head liquid pressure determined by the level of the first liquid surface66of the liquid stored in the first chamber62and the level of the second liquid surface70of the liquid stored in the second chamber68, due to the weight of the valve body101, and due to a buoyant force that acts on the valve body101in the liquid. That is, the valve body101moves between a valve-opening position, at which the valve portion103is not in contact with the valve seat333as illustrated inFIG.17, and a valve-closing position, at which the valve portion103is in contact with the valve seat333with a predetermined pressuring force. The valve-opening position of the valve body101illustrated inFIG.17is a mere example. The valve-opening position may be any position at which the rip portion105and the flange portion106of the valve portion103are not in contact with, or have at least a slight clearance from, the valve seat333, and at which therefore there is a liquid flow through the valve hole332.

The valve portion of an umbrella valve according to related art has such a shape that, for example, the thickness of the entire valve body decreases gradually as it goes toward the outer rim in the radial direction. Therefore, the valve portion of an umbrella valve according to related art has a comparatively wide flexible potion. For this reason, the valve portion of an umbrella valve according to related art deforms easily due to its high flexibility and, therefore, a pressurizing force applied when the valve portion is in contact with the valve seat is relatively weak. Because of its relatively weak pressuring force, an umbrella valve according to related art has a structure that is prone to minute leakage at a valve-closing position.

By contrast, the valve body101according to the present embodiment has a shape like a disc with an almost constant thickness and a comparatively high rigidity. Moreover, the valve body101according to the present embodiment has the rip portion105, which is a continuous seal protruding in an annular shape on the surface, of the valve plate portion103a, facing the valve seat333. The valve portion103has the annular flange portion106, which extends outward in the radial direction from the periphery of the valve plate portion103a. As described here, the valve body101includes the annular rip portion105and the annular flange portion106located on the outer-rim side to surround the rip portion105. When the on-off valve36is closed, continuous sealing is provided by the press contact of the rip portion105with the valve seat333, and the flange portion106is pressed in a slightly deformed state against the surface of the valve seat333outside the continuous seal. Therefore, a necessary pressurizing force can be obtained when the valve body101is in contact with the valve seat333due to the closing of the on-off valve36.

Moreover, since the on-off valve36has the plurality of valve holes332whose cross-sectional flow-passage area size is comparatively small as illustrated in FIG.17, pressure loss is great due to comparatively large flow resistance at the time of opening. Therefore, in order to reduce pressure loss, two on-off valves36may be provided side by side as in the example illustrated inFIG.17. The presence of the two on-off valves36increases the total cross-sectional flow-passage area size of the valve holes332and thus reduces pressure loss.

The on-off valve36is a differential pressure regulating valve that includes a float-type valve body101that opens and closes by a hydraulic head difference in the level of the liquid surface between the first chamber62and the second chamber68. The term “float-type valve body” as used herein means a differential pressure regulating valve body that opens and closes by movement of the valve body101that is in a state of floating in the liquid because of a difference in liquid pressure due to a hydraulic head difference between the first chamber62and the second chamber68, without using any urging member such as a spring that urges the valve body101in a valve-closing direction. Since the on-off valve36is a float-type valve that can be opened by a small hydraulic head difference, it opens immediately when there is even a slight difference in liquid level between the first liquid surface66and the second liquid surface70. Therefore, it is possible to adjust the second liquid surface70into the same level as the first liquid surface66, and a difference in liquid level between the first liquid surface66and the second liquid surface70does not occur easily.

FIG.18is a graph that illustrates, for comparison, a pressurizing force applied to the valve seat333by the valve body of an umbrella valve according to related art when closed and a pressurizing force applied to the valve seat333by the valve body101according to the present embodiment when closed. In the graph, the horizontal axis represents reservoir pressurizing force (kPa) which the liquid stored in the second chamber68receives from the valve body, and the vertical axis represents seal pressure (kPa) applied when the valve body is in contact with the valve seat333. The line L1indicated by a solid line inFIG.18shows seal pressure versus reservoir pressurizing force of the valve body101according to the present embodiment, and the line L2indicated by a dot-and-dash line inFIG.18shows seal pressure versus reservoir pressurizing force of the valve body of an umbrella valve according to related art. As can be seen from the graph ofFIG.18, the seal pressure versus reservoir pressurizing force of the valve body101according to the present embodiment is approximately twice as high as the seal pressure versus reservoir pressurizing force of the valve body of the umbrella valve according to related art. This shows that the seal pressure is made approximately twice as high as that of the related art by adopting a structure in which the valve body101includes the rip portion105, which is an annular continuous seal, and the annular flange portion106. The reservoir pressurizing force at the use area of the liquid ejecting apparatus11is, for example, approximately 5 to 70 (kPa). For example, the reservoir pressurizing force during cleaning is larger than the reservoir pressurizing force during liquid circulation, which is larger than the reservoir pressurizing force during printing. Even during printing in which the reservoir pressurizing force is relatively small, it is possible to ensure sufficient necessary seal pressure. The reservoir pressurizing force at the use area may be changed as may be necessary.

Wrong/Reverse Attachment of Liquid Container24

Next, with reference toFIGS.19to23, a problem that arises when the user attempts to attach the liquid container24with wrong front-rear container orientation, and a structure of the attachment portion28for solving the problem, will now be explained.FIG.19illustrates a state in which the user attaches the liquid container24with correct front-rear container orientation in the present embodiment.FIGS.20to22illustrate a structure of the attachment portion28according to related art for explaining a problem that arises when the user attempts to attach the liquid container24with wrong front-rear container orientation.FIG.23illustrates a structure of the attachment portion28according to the present embodiment.

As illustrated inFIG.19, when the liquid container24is attached with correct front-rear container orientation, the liquid container24is inserted straight horizontally into the frame80like a box through the insertion opening28o. The liquid container24is inserted straight along a top plate81constituting a part of the frame80. In the process of insertion of the liquid container24, the guiding portions247of the attachment portion28are brought into engagement with and into the guided portions447of the liquid container24. More specifically, as the insertion of the liquid container24into the frame proceeds, first, the two guiding portions247aare sequentially brought into engagement with and into the first guided portions447a, and then, at the final stage of attachment before completion, the second guiding portions247bare brought into engagement with and into the second guided portions447b. A stopper449for not allowing the liquid container24to be inserted farther into the frame80beyond its position is provided on the rear end face of the first guided portion447a.

Next, with reference toFIGS.20to23, a problem that arises when the user attempts to attach the liquid container24with wrong front-rear container orientation will now be explained.

As illustrated inFIG.20, in related art, even when the user attempts to attach the liquid container24with wrong front-rear container orientation, the first guiding portion247acollides with the stopper449, which is a rib located at the rear end of the first guided portion447a. Therefore, it is designed that the liquid container24cannot be inserted farther with wrong front-rear container orientation.

However, despite this design, it could happen that the user attempts to push the liquid container24inward by force. In this case, if the user attempts to push the liquid container24inward while tilting the liquid container24, as illustrated inFIG.21, the rear end portion of the liquid container24passes over the first guiding portion247aand pushes up the portion, of the top plate81, near the insertion opening28o. In this case, the upper surface of the rear end portion of the liquid container24causes the top plate81to be deformed near the insertion opening28o, and the liquid container24is inserted to a predetermined position through the insertion opening28o; therefore, there is a possibility that the liquid container24might become not detachable. Moreover, if the liquid container24is inserted deeper into the frame80beyond the position of the stopper449, as illustrated inFIG.22, it could happen that the guiding portion247ais brought into engagement with and into the guided portion447a. If this happens, the guiding portion247a, once engaged with and into the guided portion447a, cannot climb over the stopper449, resulting in a deadlock state illustrated inFIG.22, in which the liquid container24cannot be detached from the frame80.

To avoid such a deadlock state, as illustrated inFIGS.19and23, the attachment portion28according to the present embodiment has a protruding portion110on the lower surface of the top plate81of the frame80near the insertion opening28o. Even when the top plate81deforms due to the user's attempt to insert the rear end portion of the liquid container24through the insertion opening28oby force toward a space under the lower surface of the top plate81(in the vertical direction Z), the liquid container24cannot be inserted farther into the frame80because the top surface of the rear end portion of the liquid container24collides with the protruding portion110. Therefore, it is possible to avoid the liquid container24from becoming deadlocked.

Operation of Embodiment

Next, operation of the present embodiment will now be explained.

The user attaches the liquid container24to the attachment portion28of the tank unit26. Due to this attachment, the pouring outlet portion30of the liquid container24becomes connected to the first inlet portion60of the tank unit26. Such attachment of the liquid container24is performed when, for example, the liquid container24having run out of the liquid is replaced with another one24, for example, when the liquid in the tank unit26is detected as END, or when a state in which the first liquid surface66in the first chamber62is below the standard level position SH continues for longer than a predetermined period. In this case, the control portion19causes the display portion15ato display a message, etc. that prompts the user to replace the liquid container24with another one. Prompted by the message, the user replaces this liquid container24with another one.

The first inlet portion60is in communication with the first chamber62via the opening portion603, which is located at some midpoint in the vertical direction Z of the first chamber62. Liquid is supplied from the liquid container24into the first chamber62while the first vapor-phase portion62G and the inlet vapor-phase portion60G are in communication with each other via the opening portion603. Then, the first vapor-phase portion62G and the inlet vapor-phase portion60G become not in communication with each other when the first liquid surface66in the first chamber62reaches the standard level position SH (seeFIG.10), which is at some midpoint in the vertical direction Z of the first chamber62. In other words, the first vapor-phase portion62G and the inlet vapor-phase portion60G become not in communication with each other due to the reaching of the first liquid surface66at the lower end604of the regulating portion602. That is, the flow passage of air from the first vapor-phase portion62G to the inlet vapor-phase portion60G is disconnected. As a result, the supply of the liquid from the liquid container24to the first chamber62is stopped.

When the liquid is supplied from the second chamber68to the liquid ejecting head23, and the second liquid surface70therefore becomes lower in level than the first liquid surface66, the on-off valve36opens due to a hydraulic head difference between the first chamber62and the second chamber68. As a result, the liquid flows from the first chamber62to the second chamber68through the outlet flow passage34. When the liquid-level position of the first liquid surface66drops below the standard level position SH due to this flow, the first vapor-phase portion62G and the inlet vapor-phase portion60G come back into communication with each other to form an air flow passage again, and the supply of the liquid from the liquid container24to the first chamber62starts.

The first liquid surface66rises in level due to the supply of the liquid from the liquid container24to the first chamber62, and the first liquid surface66becomes higher in level than the second liquid surface70. When the liquid stored in the second chamber68is supplied to the liquid ejecting head23for liquid circulation, printing (liquid ejecting processing), and cleaning, the second liquid surface70drops in level, and the second liquid surface70becomes lower in level than the first liquid surface66.

In these cases, the level of the first liquid surface66and the level of the second liquid surface70are adjusted to become equal to each other by the opening of the on-off valve36. The on-off valve36closes when there is no longer a hydraulic head difference because the level of the first liquid surface66and the level of the second liquid surface70have become almost equal to each other. As described here, the liquid-level position of the first liquid surface66and the liquid-level position of the second liquid surface70are adjusted to the standard level position SH, meaning almost the same level (seeFIGS.2and10).

In this way, the first liquid surface66in the first chamber62is autonomously adjusted to the standard level position SH, which is a position where the first inlet portion60is connected to the first chamber62via the opening portion603at the lower end of the inlet passage601, and which is at some midpoint in the vertical direction Z of the first chamber62. That is, the first liquid surface66is autonomously adjusted to the standard level position SH, which is at the level of the lower end604of the regulating portion602serving as a partition between the inlet passage601and the first chamber62.

As illustrated inFIGS.16and17, the valve body101of the on-off valve36has the annular rip portion105, which is provided on the thick valve plate portion103a, and the annular flange portion106. Given the same reservoir pressurizing force of the second chamber68, therefore, the valve body101of the on-off valve36makes it possible to obtain seal pressure that is approximately twice as high as that of an umbrella valve according to related art (seeFIG.18). Therefore, it is possible to suppress minute leakage at the on-off valve36.

For example, when the first liquid surface66rises in level beyond the full level position due to inclination of the liquid ejecting apparatus11or for any other reason, there is a risk that the leakage of the liquid through the nozzles22of the liquid ejecting head23might occur due to a hydraulic head difference. However, in the present embodiment, when it is detected by the liquid surface detecting portion63that the liquid surface is at the full level position, or when the tilt of the tank unit26exceeding the angular threshold is detected by the tilt detecting portion98, the control portion19prohibits the liquid ejecting apparatus11from starting printing. Then, the control portion19causes the display portion15ato display a message that prompts the user to eliminate the tilt of the liquid ejecting apparatus11. Prompted by the message, the user eliminates the tilt of the liquid ejecting apparatus11. When the detection result of the tilt detecting portion98becomes less than the angular threshold as a result of the tilt elimination, the control portion19causes printing to be started.

The liquid ejecting apparatus11causes the liquid to circulate when in a standby state, in which printing is not performed. The liquid circulates by flowing through the second chamber68of the tank unit26, the supply flow passage37, the liquid ejecting head23, and the collection flow passage39and then returning to the first chamber62of the tank unit26. The supply valve38and the circulation valve40are open at this time. The second chamber68is pressurized in a state in which the first chamber62is opened to atmosphere via the first opening-to-atmosphere portion64.

As illustrated inFIG.10, in the tank unit26, the liquid supplied from the second chamber68through the outlet portion74and the supply flow passage37in an OUT direction indicated by the solid-line arrow inFIG.10flows through the inside of the liquid ejecting head23(seeFIG.2) and thereafter flows from the liquid ejecting head23through the collection flow passage39to return to the first chamber62via the second inlet portion75. The pressure of the second chamber68is higher than the pressure of the first chamber62at this time. Therefore, the on-off valve36closes. That is, the liquid ejecting apparatus11applies pressure to the inside of the second chamber68to close the on-off valve36, thereby closing the outlet flow passage34.

When this liquid circulation is performed, the liquid returning from the liquid ejecting head23to the first chamber62of the tank unit26flows into the first chamber62via the communication opening75a. It could happen that the liquid gushes out into the first chamber62from the communication opening75aat this time. However, in the present embodiment, the eave-like cover portion88is provided at a position where it faces the communication opening75ainside the first chamber62. Therefore, the liquid gushing out with great energy from the communication opening75ahits against the cover portion88, and its energy is therefore abated. Consequently, it is possible to reduce the possibility that the liquid gushing out from the communication opening75areaches an area where the liquid is not supposed to flow in, for example, the opening-to-atmosphere port33a.

The liquid that circulates flows through the filter100in the process of being supplied from the second chamber68toward the liquid ejecting head23. The filter100traps foreign objects such as air bubbles or fine dust particles contained in the liquid that circulates. Therefore, when the liquid ejecting apparatus11performs printing, the liquid after the removal of the foreign objects such as air bubbles are supplied to the liquid ejecting head23.

At least one of the supply valve38or the circulation valve40is opened during printing. The number of valves that are opened, of the supply valve38and the circulation valve40, may be determined depending on an amount of liquid ejected from the nozzles22of the liquid ejecting head23. For example, based on print data, when an ejection amount is not greater than a predetermined value, the control portion19may cause the supply valve38only to be opened. For example, based on print data, when an ejection amount is greater than a predetermined value, the control portion19may cause both the supply valve38and the circulation valve40to be opened.

When printing is performed, the switching mechanism48opens the sixth selection valve73fand the tenth selection valve73jto communicate the inside of the first chamber62with atmosphere through the opening-to-atmosphere path50and the connection flow passage52. In addition, the switching mechanism48opens the seventh selection valve73gand the eleventh selection valve73kto communicate the inside of the second chamber68with atmosphere through the pressurizing flow passage51and the connection flow passage52.

When printing is performed, based on a hydraulic head difference between the second liquid surface70inside the second chamber68and the nozzles22, and based on a hydraulic head difference between the first liquid surface66inside the first chamber62and the nozzles22, negative pressure acts on the liquid present inside the liquid ejecting head23. When printing is performed, the liquid stored in the second chamber68is supplied to the liquid ejecting head23through the supply flow passage37, and the liquid stored in the first chamber62is supplied to the liquid ejecting head23through the collection flow passage39in an OUT direction indicated by the broken-line arrow inFIG.10.

The liquid ejecting apparatus11performs pressurization cleaning of the liquid ejecting head23periodically or non-periodically. In pressurization cleaning, pressure is applied to the liquid stored in the second chamber68to pressurize the liquid present inside the liquid ejecting head23, thereby forcibly ejecting the liquid from the nozzles22. In this process, the second chamber68is pressurized in a state in which the supply valve38is open and the circulation valve40is closed. By the driving of the pressurizing portion47in the forward direction, air having flowed through the connection flow passage52and the pressurizing flow passage51enters the second chamber68via the opening-to-atmosphere portion69. As a result, the inside of the second chamber68is pressurized.

The liquid present inside the liquid ejecting head23is pressurized due to the pressurization of the liquid stored in the second chamber68in a state in which the circulation valve40is open. Pressurization cleaning for forcibly ejecting the liquid from the nozzles22of the liquid ejecting head23is performed in this way. The on-off valve36is closed due to the pressurization force of the second chamber68at this time. The liquid is ejected from the nozzles22by this pressurization cleaning into a non-illustrated cap or a non-illustrated flushing box. The liquid is collected from the cap or the flushing box to a non-illustrated waste liquid collection portion.

Effects of Embodiment

Effects of the present embodiment will now be explained.

(1) The tank unit26is configured such that liquid supplied from the liquid container24flows into it and the liquid flows out of it toward the liquid ejecting head23configured to eject the liquid. The tank unit26includes the first inlet portion60via which the liquid supplied from the liquid container24flows in; the first chamber62configured to store the liquid that flows in via the first inlet portion60; and the first opening-to-atmosphere portion64configured to open an inside of the first chamber62to atmosphere. The tank unit26further includes the outlet flow passage34to which one end is connected to the first chamber62and through which the liquid stored in the first chamber62flows out; the second chamber68connected to the other end of the outlet flow passage34and configured to store the liquid supplied from the first chamber62; and the second opening-to-atmosphere portion69configured to open an inside of the second chamber68to atmosphere. The tank unit26further includes the on-off valve36configured to open and close the outlet flow passage34. The first inlet portion60is connected to the first chamber62via the opening portion603at some midpoint in the vertical direction Z of the first chamber62. With this structure, it is possible to adjust the liquid surface of the two reservoir chambers62and68into an appropriate level without any need for performing supply control, etc.

(2) In the tank unit26, the opening portion603is located below the center inside the first chamber62in the vertical direction Z. With this structure, when there is liquid movement between the first chamber62, the second chamber68, and the liquid container24due to an ambient change, etc., it is possible to prevent an overflow of the liquid from the reservoir chamber, etc.

(3) The tank unit26further includes the liquid surface detecting portion63configured to detect the surface level of the liquid stored in the first chamber62. With this structure, it is possible to detect that the liquid left in the liquid container24has become small, and it is possible to prevent the overflow of the liquid stored in the first chamber62.

(4) In the tank unit26, the on-off valve36includes a one-way valve that tolerates flow of the liquid from the first chamber62toward the second chamber68and does not tolerate flow of the liquid from the second chamber68toward the first chamber62. This structure makes a valve driver unnecessary.

(5) In the tank unit26, when viewed in the vertical direction Z, the first chamber62and the second chamber68overlap at least partially. This structure realizes an efficient layout of the first chamber62and the second chamber68.

(6) The tank unit26further includes the outlet portion74that is in communication with the second chamber68, the liquid stored in the second chamber68being configured to flow out via the outlet portion74toward the liquid ejecting head23; and the second inlet portion75that is in communication with the first chamber62, the liquid collected from the liquid ejecting head23being configured to flow in via the second inlet portion75. This structure makes it possible to keep the liquid surface of the first chamber62and the liquid surface of the second chamber68at the same surface level.

(7) The tank unit26further includes the filter100provided between the second chamber68and the outlet portion74and configured to trap foreign objects contained in the liquid. This structure makes it possible to trap foreign objects mixed in the process of replacement of the liquid container24, foreign objects mixed in the process of circulation, and the like.

(8) In the tank unit26, the first chamber62has the cover portion88inside; and the cover portion88is provided over the second inlet portion75formed in a lower surface inside the first chamber62. This structure makes it possible to prevent ink collected into the first chamber62from being scattered in the first chamber62all around.

(9) The liquid ejecting apparatus includes the liquid ejecting head23configured to eject liquid; the tank unit26; the supply flow passage37that provides communication between the outlet portion74and the liquid ejecting head23; and the collection flow passage39that provides communication between the liquid ejecting head23and second inlet portion75. The same effects as those of the tank unit26can be obtained from the liquid ejecting apparatus11having this structure.

(10) The liquid ejecting apparatus11further includes the tilt detecting portion98that detects a tilt of the tank unit26. This structure makes it possible to reduce an amount of change in the liquid surface due to a tilt. Therefore, it is possible to reduce variation in liquid surface detection.

(11) The liquid ejecting apparatus11further includes the pressurizing portion47that is in communication with the second opening-to-atmosphere portion69and is configured to apply pressure to the inside of the second chamber68. This structure makes it possible to perform pressurization cleaning.

The present embodiment may be modified as described below. The present embodiment and the following modification examples may be combined with one another as long as they are not technically contradictory to one another.

The first inlet portion60may have a conduit such as a pipe, a hose, a tube, etc. extending in such a way as to have a directional component in the vertical direction Z inside the first chamber62.

The opening plane of the opening portion603may be a horizontal plane. The opening plane of the opening portion603may be inclined in a direction that is the opposite of the direction illustrated inFIG.10. The angle of the opening plane of the opening portion603with respect to the horizontal plane may be changed as may be necessary. It is sufficient as long as the opening portion603is oriented downward. That is, it is sufficient as long as the direction of a line normal to the opening plane of the opening portion603is either the vertical direction Z or any direction between the vertical direction Z and the horizontal direction.

The first inlet portion60may extend in the vertical direction Z without any inclination.

The inlet passage601of the first inlet portion60may be a curved flow passage. It is sufficient as long as the first inlet portion60is connected via the opening portion603at some midpoint in the vertical direction Z of the first chamber62. As long as this is met, the flow-passage shape of the inlet passage601from the inlet60aof the first inlet portion60to the opening portion603may be any shape. That is, it is sufficient as long as the lower end of the regulating portion602serving as a partition between the first chamber62and the inlet passage601is at some midpoint in the vertical direction Z of the first chamber62. The opening plane of the opening portion603as viewed in the direction along the Y axis may be inclined with respect to the horizontal plane. In this case, the level of the first liquid surface66is defined by the highest part of the opening plane of the opening portion603as viewed in the direction along the Y axis.

The on-off valve36may be controlled by the control portion19. The on-off valve36may be, for example, an electromagnetic valve. The on-off valve36may be a flow regulating valve whose flow at the time of opening can be regulated.

The pressurizing portion47is not limited to a tube pump. It may be any other kind of pump. For example, it may be a diaphragm pump, a gear pump, or the like.

The tank unit26is not limited to an internal tank unit disposed inside the body of the liquid ejecting apparatus11. The tank unit26may be an external tank unit connected to the body through a tube or the like.

The liquid container24is not limited to a cartridge such as an ink cartridge. The liquid container24may be a tank configured to be detachably attached to the attachment portion28.

The first reservoir portion33or the second reservoir portion35may have a window portion through which the user is able to visually confirm the amount of liquid.

In the embodiment, the on-off valve36may be omitted. For example, both of the first chamber62and the second chamber68may be pressurized when cleaning is performed. Such a technical concept is also encompassed within the scope of the embodiment. Even when modified as in such a technical concept, it is possible to provide the tank unit26and the liquid ejecting apparatus11capable of adjusting the liquid surface of the two reservoir chambers62and68into an appropriate level with a simple structure.

The second inlet portion75may be provided on the second reservoir portion35, and the liquid coming from the liquid ejecting head23may return to the second chamber68through the collection flow passage39when the liquid is circulated.

The liquid ejecting apparatus may be an ink-jet textile printing apparatus. The textile printing apparatus may include the tank unit26.

The cleaning may be suction cleaning, instead of pressurization cleaning. In the suction cleaning, a cap is brought in contact with the periphery of the nozzle surface21of the liquid ejecting head23in such a way as to enclose all of the nozzles22. Liquid is forcibly discharged through the nozzles by making the pressure of the closed space enclosed by the cap and the nozzle surface21negative by driving a suction pump.

The liquid ejecting apparatus11may be configured to eject any other kind of liquid, instead of ink. The state of liquid ejected in the form of a micro droplet from the liquid ejecting apparatus encompasses a particulate droplet, a tear-shaped droplet, and a droplet that forms a thready tail. “Liquid” mentioned herein may be made of any material that can be ejected from the liquid ejecting apparatus. For example, “liquid” may be any matter that is in a liquid phase, including but not limited to: a matter that is in a state of liquid having high viscosity or low viscosity, fluid such as sol or gel water, other inorganic solvent or organic solvent, solution, liquid resin, liquid metal, metal melt, etc. “Liquid” encompasses not only liquid as a state of matter but also liquid made as a result of dissolution, dispersion, or mixture of particles of a functional material made of a solid such as pigment or metal particles, etc. into/with a solvent. Ink described in the foregoing embodiment, pretreatment liquid, and post-treatment liquid, etc. are typical examples of “liquid”.

Technical concepts derivable from the foregoing embodiment and from its modification examples, and the operational effects thereof, will be described below.

(A) A tank unit is configured such that liquid supplied from a liquid container flows into it and the liquid flows out of it toward a liquid ejecting head configured to eject the liquid. The tank unit includes: a first inlet portion via which the liquid supplied from the liquid container flows in; a first chamber configured to store the liquid that flows in via the first inlet portion; a first opening-to-atmosphere portion configured to open an inside of the first chamber to atmosphere; an outlet flow passage to which one end is connected to the first chamber; a second chamber connected to the other end of the outlet flow passage and configured to store the liquid supplied from the first chamber; a second opening-to-atmosphere portion configured to open an inside of the second chamber to atmosphere; and an on-off valve configured to open and close the outlet flow passage, wherein the first inlet portion is connected to the first chamber via an opening portion at some midpoint in a vertical direction of the first chamber.

With this structure, it is possible to adjust the liquid surface of the two reservoir chambers into an appropriate level without any need for performing supply control, etc.

(B) In the above tank unit, the opening portion may be located below the center inside the first chamber in the vertical direction.

With this structure, when there is liquid movement between the first chamber, the second chamber, and the liquid container due to an ambient change, etc., it is possible to prevent an overflow of the liquid from the reservoir chamber, etc.

(C) The above tank unit may further include a liquid surface detecting portion configured to detect a surface level of the liquid stored in the first chamber.

With this structure, it is possible to detect that the liquid left in the liquid container has become small, and it is possible to prevent the overflow of the liquid stored in the first chamber.

(D) In the above tank unit, the on-off valve includes a one-way valve that tolerates flow of the liquid from the first chamber toward the second chamber and does not tolerate flow of the liquid from the second chamber toward the first chamber.

This structure makes a valve driver unnecessary.

(E) In the above tank unit, when viewed in the vertical direction, the first chamber and the second chamber may overlap at least partially.

This structure realizes an efficient layout of the first chamber and the second chamber.

(F) The above tank unit may further include: an outlet portion that is in communication with the second chamber, the liquid stored in the second chamber being configured to flow out via the outlet portion toward the liquid ejecting head; and a second inlet portion that is in communication with the first chamber, the liquid collected from the liquid ejecting head being configured to flow in via the second inlet portion.

This structure makes it possible to keep the liquid surface of the first chamber and the liquid surface of the second chamber at the same surface level.

(G) The above tank unit may further include: a filter provided between the second chamber and the outlet portion and configured to trap foreign objects contained in the liquid.

This structure makes it possible to trap foreign objects mixed in the process of replacement of the liquid container, foreign objects mixed in the process of circulation, and the like.

(H) In the above tank unit, the first chamber may have a cover portion inside; and the cover portion may be provided over the second inlet portion formed in a lower surface inside the first chamber.

This structure makes it possible to prevent ink collected into the first chamber from being scattered in the first chamber all around.

(I) A liquid ejecting apparatus includes: a liquid ejecting head configured to eject liquid; the above tank unit; a supply flow passage that provides communication between the outlet portion and the liquid ejecting head; and a collection flow passage that provides communication between the liquid ejecting head and second inlet portion.

The same effects as those of the above tank unit can be obtained from the liquid ejecting apparatus having this structure.

(J) The above liquid ejecting apparatus may further include: a tilt detecting portion that detects a tilt of the tank unit.

This structure makes it possible to reduce an amount of change in the liquid surface due to a tilt. Therefore, it is possible to reduce variation in liquid surface detection.

(K) The above liquid ejecting apparatus may further include: a pressurizing portion that is in communication with the second opening-to-atmosphere portion and is configured to apply pressure to an inside of the second chamber.

This structure makes it possible to perform pressurization cleaning.