JP2013184363A - Liquid ejection device, and liquid stirring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit entering of air (air bubbles) when a head section is refilled with liquid.SOLUTION: A liquid ejection device includes: a head section which ejects liquid to a medium; a first liquid reservoir section which stores the liquid; a second liquid reservoir section which stores the liquid fed from the first liquid reservoir section and is used to feed it back to the first liquid reservoir section; a first channel through which the first liquid reservoir section and the head section communicate with each other; a second channel through which the first channel and the second liquid reservoir section communicate with each other; a third channel through which the second liquid reservoir section and the second channel communicate with each other; and a liquid supply section which allows the second liquid reservoir section to store the liquid by making the liquid flow via the first channel and the second channel from the first liquid reservoir section, and allows the first liquid reservoir section to store the liquid by making the liquid flow via the third channel, the second channel and the first channel from the second liquid reservoir section.

Description

  The present invention relates to a liquid ejection device and a liquid stirring method.

  As an example of a liquid ejecting apparatus, an ink jet printer that prints an image by ejecting a liquid such as ink onto various media such as paper and film is known. The ink jet printer includes a storage unit that stores a liquid, a head unit that discharges the liquid onto a medium, and a flow path that allows the liquid to flow from the storage unit toward the head unit (for example, Patent Document 1).

JP-A-6-79876

In such a liquid ejecting apparatus, air (bubbles) may enter the housing portion. For this reason, when liquid is supplied to the head unit from the storage unit, air (bubbles) flowing out from the storage unit may flow through the flow path and be mixed into the head unit. This air may cause dot dropout when the head unit ejects liquid, which may deteriorate the printed image.
The present invention has been made in view of such a problem, and an object thereof is to suppress air (bubbles) from being mixed when liquid is supplied to the head portion.

The main invention for solving the above problems is:
A head unit for discharging liquid onto a medium;
A first liquid storage section for storing a liquid;
A second liquid container used to store the liquid sent out from the first liquid container and send it back to the first liquid container;
A first flow path for communicating the first liquid storage portion and the head portion;
A second flow path for communicating the first flow path with the second liquid storage portion;
A third flow path for communicating the second liquid storage portion and the second flow path;
By flowing a liquid from the first liquid storage portion via the first flow path and the second flow path, the liquid is stored in the second liquid storage section, and the first liquid storage section A liquid supply section for storing the liquid in the first liquid storage section by flowing the liquid through the three flow paths, the second flow path, and the first flow path;
It is a liquid discharge apparatus characterized by having.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a schematic diagram illustrating a configuration of a printer. 2 is a block diagram illustrating a configuration example of a printer 1. FIG. It is a figure explaining the structural example of the ink supply unit 35 which concerns on this embodiment. FIG. 4 is a schematic side view of a sub ink tank ST (preliminary ink tank SST), showing a state after ink in the sub ink tank ST (preliminary ink tank SST) has flowed out. It is a figure explaining the structural example of the ink replenishment unit in a comparative example. It is a figure explaining the stirring operation of the ink in a comparative example, Comprising: It is a figure which shows the state before starting sending out of the ink from the sub ink tank ST to the reserve ink tank SST. It is a figure explaining the stirring operation of the ink in a comparative example, Comprising: It is a figure which shows the state which poured the ink from the sub ink tank ST to the reserve ink tank SST. It is a figure explaining the stirring operation of the ink in a comparative example, Comprising: It is a figure which shows the state which poured sub ink tank ST ink from the reserve ink tank SST. It is a figure explaining the stirring operation of the ink in a comparative example, Comprising: It is a figure which shows the state which poured the ink from the sub ink tank ST to the head unit 30. FIG. FIG. 5 is a diagram illustrating an ink agitation operation in the present embodiment, and is a diagram illustrating a state before starting to send ink from a sub ink tank ST to a spare ink tank SST. It is a figure explaining the stirring operation of the ink in this embodiment, Comprising: It is a figure which shows the state which flowed the ink from the sub ink tank ST to the reserve ink tank SST. It is a figure explaining the stirring operation of the ink in this embodiment, Comprising: It is a figure which shows the state which flowed the sub ink tank ST ink from the reserve ink tank SST.

  At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

That is, a head unit that ejects liquid onto a medium;
A first liquid storage section for storing a liquid;
A second liquid container used to store the liquid sent out from the first liquid container and send it back to the first liquid container;
A first flow path for communicating the first liquid storage portion and the head portion;
A second flow path for communicating the first flow path with the second liquid storage portion;
A third flow path for communicating the second liquid storage portion and the second flow path;
By flowing a liquid from the first liquid storage portion via the first flow path and the second flow path, the liquid is stored in the second liquid storage section, and the first liquid storage section A liquid supply section for storing the liquid in the first liquid storage section by flowing the liquid through the three flow paths, the second flow path, and the first flow path;
It is a liquid discharge apparatus characterized by having.
According to such a liquid ejecting apparatus, it is possible to suppress the mixing of air (bubbles) when supplying liquid to the head unit.

Further, from the first liquid storage section that stores the liquid, the first flow path that connects the first liquid storage section and the head section that discharges the liquid to the medium, and the first flow path and the first liquid storage section The liquid is caused to flow through the second flow path that communicates with the second liquid storage unit used to store the sent liquid and send it back to the first liquid storage unit. Accommodating in the accommodating part;
By flowing the liquid from the second liquid storage part via the third flow path that connects the second liquid storage part and the second flow path, the second flow path, and the first flow path, Storing liquid in the first liquid storage portion;
It is a liquid stirring method characterized by having.
According to such a liquid stirring method, mixing of air (bubbles) can be suppressed when supplying liquid to the head portion.

=== Embodiment ===
<<< Configuration Example of Printer 1 >>>
A configuration example of a printer 1 as an example of a liquid ejection apparatus (in this embodiment, an ink jet printer, in particular, a lateral scan type label printing machine) will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating the configuration of the printer 1. FIG. 2 is a block diagram illustrating a configuration example of the printer 1.

In the following description, when referring to “up and down direction” and “left and right direction”, the direction indicated by the arrow in FIG. 1 is used as a reference. In addition, the “front-rear direction” refers to a direction orthogonal to the paper surface in FIG.
Further, in the present embodiment, as an example of a medium on which the printer 1 records an image, a paper wound in a roll shape (hereinafter referred to as “roll paper (continuous paper)”) will be described.

  As shown in FIGS. 1 and 2, the printer 1 according to the present embodiment includes a transport unit 20 and a transport path through which the transport unit 20 transports the roll paper 2 (in FIG. 1, the transport path is a roll A feed unit 10, a platen 29, and a take-up unit 90, along the paper roll shaft 18 to the roll paper take-up drive shaft 92. The head unit 30 that performs image printing by discharging a plurality of types of ink in the printing region R on the transport path, the ink supply unit 35, the carriage unit 40, the cleaning unit 45, the heater unit 70, and the platen 29 Blower unit 80 for sending air to the roll paper 2 and a controller for controlling these units and controlling the operation as the printer 1 60, and a detector group 50, a.

  The feeding unit 10 feeds the roll paper 2 to the transport unit 20. The feeding unit 10 includes a roll paper winding shaft 18 around which the roll paper 2 is wound and rotatably supported, and a relay roller 19 for winding the roll paper 2 fed from the roll paper winding shaft 18 and guiding the roll paper 2 to the transport unit 20. And have.

  The transport unit 20 transports the roll paper 2 sent by the feeding unit 10 along a preset transport path. As shown in FIG. 1, the transport unit 20 includes a relay roller 21 that is positioned horizontally to the right of the relay roller 19, a relay roller 22 that is positioned obliquely downward to the right when viewed from the relay roller 21, and the relay roller 22. 1st conveyance roller 23 located in the upper right direction as viewed from the platen 29 (upstream side in the conveyance direction) and a right side as viewed from the first conveyance roller 23 (downstream in the conveyance direction as viewed from the platen 29). The second transport roller 24, the reverse roller 25 positioned vertically downward as viewed from the second transport roller 24, the relay roller 26 positioned rightward as viewed from the reverse roller 25, and upward as viewed from the relay roller 26. And a delivery roller 27 which is positioned.

The relay roller 21 is a roller that winds the roll paper 2 sent from the relay roller 19 from the left side and loosens it downward.
The relay roller 22 is a roller that winds the roll paper 2 sent from the relay roller 21 from the left side and conveys it obliquely upward to the right.

  The first transport roller 23 includes a first drive roller 23a driven by a motor (not shown), and a first driven roller 23b arranged to face the first drive roller 23a with the roll paper 2 interposed therebetween. have. The first transport roller 23 is a roller that pulls up the roll paper 2 slacked downward and transports it to the printing region R facing the platen 29. The first transport roller 23 is configured to temporarily stop transport during a period in which image printing is performed on a portion of the roll paper 2 on the print region R. In addition, the conveyance amount of the roll paper 2 positioned on the platen 29 is adjusted by rotating the first driven roller 23b in accordance with the rotational drive of the first drive roller 23a by the drive control of the controller 60.

  As described above, the transport unit 20 has a mechanism for transporting the portion of the roll paper 2 wound between the relay rollers 21 and 22 and the first transport roller 23 by slacking it downward. The slackness of the roll paper 2 is monitored by the controller 60 based on a detection signal from a slack detection sensor (not shown). Specifically, when a portion of the roll paper 2 slackened between the relay rollers 21 and 22 and the first transport roller 23 is detected by the slack detection sensor, a tension of an appropriate magnitude is applied to the portion. Therefore, the transport unit 20 can transport the roll paper 2 in a relaxed state. On the other hand, when the portion of the roll paper 2 that has been loosened is not detected by the slack detection sensor, an excessive amount of tension is applied to the portion, so that the roll paper 2 is transported by the transport unit 20. It is temporarily stopped and the tension is adjusted to an appropriate magnitude.

  The second transport roller 24 includes a second drive roller 24a driven by a motor (not shown), and a second driven roller 24b disposed so as to face the second drive roller 24a with the roll paper 2 interposed therebetween. have. The second transport roller 24 is a roller that transports the portion of the roll paper 2 on which the image is recorded by the head unit 30 in the horizontal right direction along the support surface of the platen 29 and then transports it vertically downward. Thereby, the conveyance direction of the roll paper 2 is changed. The second driven roller 24b rotates as the second drive roller 24a is driven to rotate by the drive control of the controller 60, whereby a predetermined amount given to the portion of the roll paper 2 located on the platen 29 is obtained. Tension is adjusted.

The reversing roller 25 is a roller that wraps the roll paper 2 sent from the second conveying roller 24 from the upper left side and conveys it diagonally upward to the right.
The relay roller 26 is a roller that winds the roll paper 2 sent from the reversing roller 25 from the lower left side and conveys it upward.
The delivery roller 27 winds the roll paper 2 sent from the relay roller 26 from the lower left side and sends it to the take-up unit 90.

  As described above, the roll paper 2 moves sequentially through the rollers, whereby a transport path for transporting the roll paper 2 is formed. The roll paper 2 is intermittently conveyed along the conveyance path by the conveyance unit 20 in units of areas corresponding to the printing areas R.

  The head unit 30 is for recording an image on a portion of the roll paper 2 located in the printing region R on the transport path. That is, the head unit 30 forms an image by ejecting ink from the ink ejection nozzles onto the portion of the roll paper 2 that has been fed into the printing region R (on the platen 29) on the transport path by the transport unit 20. In the present embodiment, the head unit 30 has M heads 31.

  Each head 31 has an ink discharge nozzle row in which ink discharge nozzles are arranged in the row direction on the lower surface (that is, the nozzle surface). In the present embodiment, ink composed of a plurality of ink ejection nozzles # 1 to #N for each color such as white (W), cyan (C), magenta (M), yellow (Y), black (K), and the like. A discharge nozzle row is provided. The ink discharge nozzles # 1 to #N of each ink discharge nozzle row are linearly arranged in a cross direction that intersects the transport direction of the roll paper 2 (that is, the cross direction is the above-described row direction). . The respective ink discharge nozzle rows are arranged in parallel with a space therebetween along the transport direction.

  Each of the ink discharge nozzles # 1 to #N is provided with a piezo element (not shown) as a drive element for discharging ink droplets. When a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element expands according to the voltage application time and deforms the side wall of the ink flow path. As a result, the volume of the ink flow path contracts according to the expansion and contraction of the piezo element, and the ink corresponding to the contraction is ejected from the ink ejection nozzles # 1 to #N of the respective colors as ink droplets.

  Then, M such heads 31 are arranged in the intersecting direction (the row direction), thereby forming the head unit 30. Therefore, the head unit 30 has M × N ink ejection nozzles for each color.

  The ink supply unit 35 is for supplying ink to the head unit 30 when the amount of ink in the head unit 30 decreases due to ink ejection by the head 31. The head unit 30 (head 31) can perform image printing by ejecting the ink supplied from the ink supply unit 35. The ink supply unit 35 is provided for each ink color. The specific configuration of the ink supply unit 35 will be described in detail later.

  The carriage unit 40 is for moving the head unit 30 (head 31). The carriage unit 40 is supported by a carriage guide rail 41 (indicated by a two-dot chain line in FIG. 1) extending in the transport direction (left-right direction) and reciprocally movable along the carriage guide rail 41 in the transport direction (left-right direction). A carriage 42 and a motor (not shown). The carriage 42 in the present embodiment has four sub-carriages, and a plurality of heads 31 are provided for each sub-carriage. The carriage 42 is configured to move in the transport direction (left-right direction) together with the head unit 30 (head 31) by driving a motor (not shown). In addition, when the head unit 30 (head 31) is cleaned after image printing, the carriage 42 is integrated with the head unit 30 (head 31) along the carriage guide rail 41 on the upstream side (from the platen 29). It moves to the upstream side in the transport direction as viewed, and stops at the home position HP for cleaning (see FIG. 1).

  The cleaning unit 45 is provided at the home position HP and is for cleaning the head unit 30 (head 31). The cleaning unit 45 includes a cap (not shown), a suction pump, and the like. When the carriage 42 is positioned at the home position HP, the cap is in close contact with the lower surface (nozzle surface) of the head 31. When the suction pump operates in such a state that the cap is in close contact, the ink in the head 31 is sucked together with the thickened ink and paper dust. In this way, the clogged nozzle recovers from the non-ejection state, thereby completing the head cleaning.

  The platen 29 supports the part of the roll paper 2 located in the printing region R on the conveyance path and heats the part. As shown in FIG. 1, the platen 29 is provided in correspondence with the printing region R on the conveyance path, and in a region along the conveyance path between the first conveyance roller 23 and the second conveyance roller 24. Has been placed. The platen 29 can heat the portion of the roll paper 2 by receiving supply of heat generated by the heater unit 70.

  The heater unit 70 is for heating the roll paper 2 and has a heater (not shown). This heater has a nichrome wire, and the nichrome wire is arranged inside the platen 29 so as to be at a fixed distance from the support surface of the platen 29. For this reason, when the heater is energized, the nichrome wire itself generates heat, and heat can be conducted to the portion of the roll paper 2 located on the support surface of the platen 29. Since this heater is configured by incorporating a nichrome wire in the entire area of the platen 29, heat can be uniformly conducted to the portion of the roll paper 2 on the platen 29. In the present embodiment, the portion of the roll paper 2 is uniformly heated so that the temperature of the portion of the roll paper 2 on the platen is 45 ° C. Thereby, the ink landed on the part of the roll paper 2 can be dried.

  The blower unit 80 is for sending wind to the roll paper 2 on the platen 29. The blower unit 80 includes a fan 81 and a motor (not shown) that rotates the fan 81. The fan 81 rotates to send wind to the roll paper 2 on the platen 29 and dry the ink landed on the roll paper 2. As shown in FIG. 1, a plurality of fans 81 are provided on an openable / closable cover (not shown) provided on the main body. Each fan 81 is positioned above the platen 29 when the cover is closed, and faces the support surface of the platen 29 (the roll paper 2 on the platen 29).

  The winding unit 90 is for winding the roll paper 2 (image-printed roll paper) sent by the transport unit 20. This take-up unit 90 is fed from the relay roller 91 that is rotatably supported by the relay roller 91 for winding the roll paper 2 sent from the feed roller 27 from the upper left side and conveying it to the lower right side. A roll paper take-up drive shaft 92 for taking up the roll paper 2.

  The controller 60 is a control unit for controlling the printer 1. As shown in FIG. 2, the controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer 1. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like. The CPU 62 controls each unit by a unit control circuit 64 according to a program stored in the memory 63.

  The detector group 50 is for monitoring the situation in the printer 1. For example, the above-described slack detection sensor, a rotary encoder attached to the conveyance roller and used for controlling the conveyance of the roll paper 2, and the like A paper detection sensor for detecting the presence or absence of the roll paper 2 to be detected, a linear encoder for detecting the position of the carriage 42 (or head 31) in the transport direction (left-right direction), and a paper edge (edge) in the width direction of the roll paper 2 ) There is a paper edge position detection sensor that detects the position.

<<< About Ink Supply Unit 35 >>>
Here, a configuration example of the ink supply unit 35 according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram illustrating a configuration example of the ink supply unit 35 according to the present embodiment. FIG. 4 is a schematic side view of the sub ink tank ST (or the spare ink tank SST) and shows a state after the ink in the sub ink tank ST (or the spare ink tank SST) has flowed out. .

  The ink supply unit 35 according to this embodiment is for supplying ink to the head unit 30 and is provided for each ink color. That is, each ink supply unit 35 supplies ink of a different color to the corresponding head 31. For example, an ink supply unit for white for supplying white ink, an ink supply unit for cyan for supplying cyan ink, an ink supply unit for magenta for supplying magenta ink, A yellow ink supply unit for supplying yellow ink, a black ink supply unit for supplying black ink, and the like are provided. In the following description, since each ink supply unit 35 has the same configuration, the white ink supply unit 35 that supplies white ink (W) will be described as an example. The white ink is an aqueous ink using white titanium oxide (titanium dioxide) as a pigment, and is an ink used for printing a background color (white) of a color image when printing on a transparent medium.

  As shown in FIG. 3, the ink supply unit 35 includes an ink cartridge IC, a sub ink tank ST as an example of a first liquid storage unit, a spare ink tank SST as an example of a second liquid storage unit, an ink An ink supply tube 34 for flowing ink flowing out of the cartridge IC to the sub ink tank ST, a first ink supply tube 36 as an example of a first flow path for communicating the sub ink tank ST and the head unit 30, and a first An example of a second ink supply tube 37 as an example of a second flow path for communicating the ink supply tube 36 and the spare ink tank SST, and an example of a third flow path for communicating the spare ink tank SST and the second ink supply tube 37. A third ink supply tube 38 and a supply pump P as an example of a liquid supply unit That.

  The ink cartridge IC stores ink to be supplied to the head unit 30. The ink cartridge IC is configured to be detachable from the printer body.

  The sub ink tank ST temporarily stores ink supplied from the ink cartridge IC to the head unit 30. Since the sub ink tank ST is fixed inside the printer, unlike the ink cartridge IC, the sub ink tank ST cannot be attached to and detached from the printer main body.

  Here, if the ink stored in the sub ink tank ST is left for a long time, the ink may settle. Such sedimentation causes a density difference between the upper side and the lower side in the vertical direction in the sub ink tank ST. In particular, when the ink is a pigment ink such as a white ink, the density difference due to the sedimentation appears remarkably. When an image is printed using such settled ink, it gradually changes to an image having a density different from that of the original image with the passage of time. turn into.

  On the other hand, in the present embodiment, by reciprocating the ink between the sub ink tank ST and the spare ink tank SST, the ink that has settled in the sub ink tank ST is agitated to make the ink density uniform. It is improving. An example of the operation for stirring the ink will be specifically described later.

  Further, since the sub ink tank ST has flexibility, it can be bent according to the amount of ink stored. That is, the sub ink tank ST can be flexibly deformed while maintaining a certain degree of rigidity, such as expanding as the ink is filled therein and contracting as the ink is discharged to the outside. Therefore, in the ink stirring operation described later, when the sub ink tank ST is sucked by the supply pump P, it is deformed into a collapsed state as shown in FIG. In this way, by deforming the sub ink tank ST into a crushed state, it is possible to discharge all the ink stored in the sub ink tank ST. At this time, if air is mixed in the sub ink tank ST, the air also flows out from the sub ink tank ST as the ink is sucked by the supply pump P.

  The sub ink tank ST according to the present embodiment is formed in a bag shape with a transparent polyethylene-based resin. In addition, you may form in a bag shape using not only a polyethylene-type resin but metals, such as other resin which has flexibility, a silicon | silicone, or aluminum.

  The spare ink tank SST temporarily stores the ink sent from the sub ink tank ST in order to send it back to the sub ink tank ST.

  Here, as described above, since the ink stored in the sub ink tank ST settles after a long time, a density difference occurs between the upper side and the lower side in the vertical direction in the sub ink tank ST. In such a case, the ink stored in the sub ink tank ST is sequentially sent out to the spare ink tank SST side by the supply pump P. The spare ink tank SST can temporarily store the ink sent out from the sub ink tank ST one after another. Then, the ink stored in the spare ink tank SST is sent back to the sub ink tank ST again by the supply pump P.

  In this way, it is possible to stir the settled ink by reciprocating between the sub ink tank ST and the spare ink tank SST, thereby improving the uniformity of the ink density.

  Note that the spare ink tank SST is flexible, like the sub ink tank ST, and can be bent according to the amount of ink stored. Therefore, in the ink stirring operation described later, when the preliminary ink tank SST is similarly sucked by the supply pump P, it is deformed into a collapsed state as shown in FIG.

  As shown in FIG. 3, the first ink supply tube 36 forms a flow path for flowing ink from the sub ink tank ST to the head unit 30. A valve 36V is provided on the flow path.

  In the present embodiment, as shown in FIG. 3, four first ink supply tubes 361 to 364 are provided as flow paths for flowing white ink, and each tube includes the sub ink tank ST and the head unit 30. Communicate with each other. The four first ink supply tubes 361 to 364 are provided in this way because the carriage 42 in this embodiment has four sub-carriages, and a plurality of heads 31 are provided on each sub-carriage. Therefore, the white ink is supplied to each head 31 by associating the ink supply tube with each sub-carriage.

  The valve 36V is an open / close valve for opening or closing the flow path of the first ink supply tube 36. When the ink is moved between the sub ink tank ST and the spare ink tank SST, the valve 36V is supplied from the controller 60. Open / close operation is performed based on the control signal.

  In the present embodiment, as shown in FIG. 3, upstream valves 36 </ b> V <b> 1 to 36 </ b> V <b> 4 are provided corresponding to the plurality of first ink supply tubes 361 to 364, respectively.

  As shown in FIG. 3, the second ink supply tube 37 forms a flow path for connecting the first ink supply tube 36 and the spare ink tank SST. A valve 37V and a first supply pump P1 are provided on the flow path.

  In the present embodiment, as shown in FIG. 3, two second ink supply tubes 371 and 372 are provided as flow paths for flowing white ink, and the first ink supply tube 361 is provided via connectors C1 to C4. By connecting to ˜364, the sub ink tank ST and the spare ink tank SST can be communicated with each other.

  The valve 37V is an open / close valve for opening or closing the flow path of the second ink supply tube 37. When the ink is moved between the sub ink tank ST and the spare ink tank SST, the valve 37V is supplied from the controller 60. Open / close operation is performed based on the control signal.

  In the present embodiment, as shown in FIG. 3, valves 37V1 and 37V2 are provided corresponding to the plurality of second ink supply tubes 371 and 372, respectively.

  As shown in FIG. 3, the third ink supply tube 38 forms a flow path for communicating the preliminary ink tank SST and the second ink supply tube 37. A valve 38V and a second supply pump P2 are provided on this flow path.

  In the present embodiment, as shown in FIG. 3, two third ink supply tubes 381 and 382 are provided as flow paths for flowing white ink, and the second ink supply tube 371 is provided via connectors C5 and C6. , 372, the preliminary ink tank SST and the second ink supply tube 37 can be communicated with each other.

  The valve 38V is an open / close valve for opening or closing the flow path of the third ink supply tube 38. When the ink is moved between the sub ink tank ST and the spare ink tank SST, the valve 38V is supplied from the controller 60. Open / close operation is performed based on the control signal.

  In the present embodiment, as shown in FIG. 3, valves 38 </ b> V <b> 1 and 38 </ b> V <b> 2 are provided corresponding to the plurality of third ink supply tubes 381 and 382, respectively.

  The supply pump P reciprocates ink between the sub ink tank ST and the spare ink tank SST by supplying compressed air. That is, the supply pump P supplies compressed air in response to a control signal from the controller 60, thereby sucking ink in the sub ink tank ST and sending it out into the spare ink tank SST. The ink can be sucked and sent back to the sub ink tank ST.

  As shown in FIG. 3, the supply pump P according to the present embodiment sucks the ink in the sub ink tank ST and sends it to the spare ink tank SST, and the supply pump P in the spare ink tank SST. And a second supply pump P2 for sucking ink and sending it back to the sub ink tank ST. The first supply pump P1 is provided on a flow path formed by connecting the first ink supply tube 36 and the second ink supply tube 37. The second supply pump P <b> 2 is provided on a flow path formed by connecting the first ink supply tube 36, the second ink supply tube 37, and the third ink supply tube 38.

  As described above, the ink supply unit 35 according to the present embodiment connects the first ink supply tube 36 and the second ink supply tube 37 to provide a forward path when sending ink from the sub ink tank ST to the spare ink tank SST. The third ink supply tube 38, the second ink supply tube 37, and the first ink supply tube 36 are connected to form a return path when ink is sent back from the spare ink tank SST to the sub ink tank ST. . In the ink agitation operation described later, the first ink supply tube 36 used when ink is flowed in the forward path is also used when ink is flowed in the backward path. Therefore, even if the ink stirring operation is performed when air is mixed into the sub ink tank ST, the air (bubbles) can be sent back to the sub ink tank ST. Hereinafter, the stirring operation of the printer 1 according to the present embodiment will be described in detail.

<<< About Stirring Operation of Printer 1 >>>
Next, an operation example for stirring the ink that has settled in the sub ink tank ST will be described.

  If a long time elapses without using the ink stored in the sub ink tank ST, ink sedimentation occurs. The printer 1 according to the present embodiment performs a stirring operation for stirring the ink that has settled by reciprocating the ink between the sub ink tank ST and the spare ink tank SST in response to the ink settling. It is possible to improve the density uniformity of the ink stored in the ink tank ST.

  Similarly, the ink cartridge IC is settled when a long time elapses in the unused state. Since the ink cartridge IC is configured to be detachable from the printer main body, the user performs a stirring operation by removing the ink cartridge IC from the main body and shaking it up and down, so that the concentration of the ink contained in the ink cartridge IC is uniform. Can be improved.

  However, when the user mounts the ink cartridge IC on the printer body after the ink cartridge IC is stirred, air (bubbles) may enter the sub ink tank ST through the ink supply tube 34 connected to the ink cartridge IC. is there. Although a small amount of air (bubbles) enters when the ink cartridge IC is installed, a large amount of air accumulates in the sub ink tank ST by repeatedly attaching and detaching the ink cartridge IC.

  If the ink supply unit 35 is configured as in the comparative example (details will be described later), the air (bubbles) are mixed in the sub ink tank ST, and the space between the sub ink tank ST and the spare ink tank SST. If the ink is moved back and forth (when the ink is stirred), air (bubbles) may remain in the ink supply tube 36. When the ink is ejected from the head unit 30 (head 31) by the image printing or the like and the ink in the head unit 30 is consumed, the sub ink tank ST is supplemented so that the consumed ink is supplemented. The ink in the fluid flows into the head unit 30 through the first ink supply tube 36. If air (bubbles) remains in the first ink supply tube 36, the air (bubbles) together with the ink is in the head unit. 30 may adversely affect image printing.

  On the other hand, since the printer 1 of the present embodiment employs the ink supply unit 35 having the above-described configuration, the ink stirring operation is performed in a state where air is mixed into the sub ink tank ST. However, it is possible to suppress air (bubbles) from being mixed when ink is supplied to the head unit 30 (head 31).

  In the following, after describing the comparative example, the stirring operation of the printer 1 according to the present embodiment will be described.

<Comparative example>
A comparative example will be described with reference to FIGS. 5 and 6A to 6D. FIG. 5 is a diagram illustrating a configuration example of the ink supply unit in the comparative example. 6A to 6D are diagrams illustrating the ink stirring operation in the comparative example.

(Configuration of ink supply unit in comparative example)
The printer according to the comparative example includes an ink supply unit having a configuration different from that of the printer 1 according to the present embodiment. Hereinafter, the configuration of the ink supply unit in the comparative example will be described.

  As shown in FIG. 5, the ink replenishment unit of the comparative example includes an ink cartridge IC, a sub ink tank ST, a spare ink tank SST, and an ink supply for flowing ink flowing out of the ink cartridge IC to the sub ink tank ST. A tube 34, a first ink supply tube 36 for communicating the sub ink tank ST and the head unit 30, a second ink supply tube 37 for communicating the first ink supply tube 36 and the spare ink tank SST, and a supply pump P. And have.

  In the comparative example, as shown in FIG. 5, four first ink supply tubes 361 to 364 are provided, and each tube communicates the sub ink tank ST and the head unit 30 with each other. Further, valves 36V1 to 36V4 are provided corresponding to the plurality of first ink supply tubes 361 to 364, respectively.

  In the comparative example, as shown in FIG. 5, four second ink supply tubes 371 to 374 are provided and connected to the first ink supply tubes 361 to 364 via the connectors C1 to C4. The sub ink tank ST and the spare ink tank SST can be communicated with each other. Further, valves 37V1 to 37V4 are provided corresponding to the plurality of second ink supply tubes 371 to 374, respectively.

  In the comparative example, as shown in FIG. 5, a flow path formed by connecting the first ink supply tube 361 and the second ink supply tube 371, and the first ink supply tube 364 and the second ink supply tube. A first supply pump P <b> 1 is provided on a flow path formed by connecting 374. The first supply pump P1 is for sucking the ink in the sub ink tank ST and sending it out into the spare ink tank SST. Further, on the flow path formed by connecting the first ink supply tube 362 and the second ink supply tube 372 and on the flow path formed by connecting the first ink supply tube 363 and the second ink supply tube 373. A second supply pump P2 is provided. The second supply pump P2 is for sucking ink in the spare ink tank SST and sending it back to the sub ink tank ST.

  As described above, in the ink replenishment unit in the comparative example, the first ink supply tubes 361 and 364 and the second ink supply tubes 371 and 374 are connected to send ink from the sub ink tank ST to the spare ink tank SST. A forward path is formed, and the first ink supply tubes 362 and 363 and the second ink supply tubes 372 and 373 are connected to form a return path for returning ink from the preliminary ink tank SST to the sub ink tank ST. In the ink agitation operation described later, the first ink supply tube 36 used for flowing ink in the forward path is different from the first ink supply tube 36 used for flowing ink in the backward path. As a result, when the ink is reciprocated between the sub ink tank ST and the spare ink tank SST in a state where air (bubbles) is mixed in the sub ink tank ST (when the ink is stirred), the ink supply tube 36 is used. Air (bubbles) remains on the surface. Hereinafter, the stirring operation in the comparative example will be described in detail.

(Stirring operation in the comparative example)
Next, the ink stirring operation in the comparative example, that is, the operation of stirring the ink in the sub ink tank ST in a state where air (bubbles) is mixed in the sub ink tank ST will be described.

  FIG. 6A is a diagram illustrating a state before starting to send ink from the sub ink tank ST to the spare ink tank SST. That is, before starting stirring, the sub ink tank ST contains ink and air. Since the ink before the start of stirring has settled, there is a difference in density between the upper side and the lower side of the sub ink tank ST. The spare ink tank SST contains neither ink nor air (hereinafter referred to as “hollow state”). The first ink supply tube 36 and the second ink supply tube 37 are filled with ink, respectively. In the comparative example, the stirring operation is started from this state. This will be specifically described below.

  First, as shown in FIG. 6B, the controller 60 closes the valves 37V2 and 37V3, opens the valves 36V, 37V1, and 37V4, and drives only the first supply pump P1. Then, the ink in the sub ink tank ST is sequentially sent out toward the spare ink tank SST. Then, the ink that flows out from the sub ink tank ST flows to the second ink supply tubes 371 and 374 via the first ink supply tubes 361 and 364, respectively, and is stored one after another in the spare ink tank SST. When all of the ink has flowed out, the air finally flows out from the sub ink tank ST to the first ink supply tubes 361 and 364. The driving of the first supply pump P1 is continued until all the ink and air in the sub ink tank ST flow out. As a result, the sub ink tank ST is in a hollow state, and the spare ink tank SST is in a state filled with ink. The first ink supply tubes 361 and 364 are in a state where air (bubbles) remains.

  Next, as shown in FIG. 6C, the controller 60 closes the valves 37V1 and 37V4 and opens the valves 36V, 37V2, and 37V3, and drives only the second supply pump P2. Thus, the ink in the preliminary ink tank SST is sequentially sent back toward the sub ink tank ST. Then, the ink flowing out from the preliminary ink tank SST flows through the second ink supply tubes 372 and 373 to the first ink supply tubes 362 and 363, respectively, and is successively stored in the sub ink tank ST. The driving of the second supply pump P2 is continued until all the ink in the spare ink tank SST has flowed out. As a result, the preliminary ink tank SST is in a hollow state, and the sub ink tank ST is in a state filled with ink.

  In this way, when the ink reciprocates between the sub ink tank ST and the spare ink tank SST, the ink that has settled in the sub ink tank ST is stirred and the ink density is made uniform.

  However, if the ink in the sub ink tank ST is made to flow through the first ink supply tube 36 and is supplied to the head unit 30 (head 31) after such a stirring operation, as shown in FIG. 6D, the first ink supply is performed. Since air (bubbles) remains in the tubes 361 and 364, the air (bubbles) is pushed by the flow of ink and flows to the head side, and eventually reaches the head unit 30 (head 31). . As a result, the air (bubbles) may cause ejection failure when the head unit 30 (head 31) ejects ink, leading to deterioration of the printed image.

<Agitating operation in this embodiment>
Next, an ink stirring operation in the printer 1 according to the present embodiment, that is, an operation of stirring the ink in the sub ink tank ST in a state where air (bubbles) is mixed in the sub ink tank ST is shown in FIGS. A description will be given using 7C. 7A to 7C are diagrams for explaining the ink stirring operation in the present embodiment.

  FIG. 7A is a diagram illustrating a state before starting to send ink from the sub ink tank ST to the spare ink tank SST. Similar to the comparative example, before the start of stirring, the sub ink tank ST contains ink and air. Since the ink before stirring has settled, there is a difference in density between the upper side and the lower side of the sub ink tank ST. The spare ink tank SST is in a hollow state. Further, the first ink supply tube 36, the second ink supply tube 37, and the third ink supply tube 38 are filled with ink, respectively. In this embodiment, the stirring operation is started from this state. This will be specifically described below.

  First, as shown in FIG. 7B, the controller 60 closes the valve 38V, opens the valve 36V and the valve 37V, and drives only the first supply pump P1, thereby driving the sub ink tank. The ink in ST is sequentially sent out toward the spare ink tank SST. Then, the ink flowing out from the sub ink tank ST flows to the second ink supply tube 37 via the first ink supply tube 36, and is successively stored in the spare ink tank SST. When all of the ink has flowed out, the air finally flows out from the sub ink tank ST to the first ink supply tube 36. In the present embodiment, the driving of the first supply pump P1 is continued until the sub ink tank ST is in a collapsed state (see FIG. 4), and all the ink and air in the sub ink tank ST flow out. . As a result, the sub ink tank ST is in a hollow state, and the spare ink tank SST is in a state filled with ink. The first ink supply tube 36 is in a state where air (bubbles) remains.

  Next, as shown in FIG. 7C, the controller 60 closes the valve 37V, opens the valve 36V and the valve 38V, and drives only the second supply pump P2. The ink in the tank SST is sequentially sent back toward the sub ink tank ST. Then, the ink flowing out from the preliminary ink tank SST flows through the third ink supply tube 38 to the second ink supply tube 37 and then to the first ink supply tube 36 to enter the sub ink tank ST. It is accommodated one after another. In the present embodiment, the driving of the second supply pump P2 is continued until the spare ink tank SST is in a collapsed state (see FIG. 4), and all the ink in the spare ink tank SST flows out. As a result, the preliminary ink tank SST is in a hollow state, and the sub ink tank ST is in a state filled with air (bubbles) and ink remaining in the first ink supply tube 36.

  As a result, the ink reciprocatingly moves between the sub ink tank ST and the spare ink tank SST, whereby the ink that has settled in the sub ink tank ST is stirred and the ink density is made uniform. Also, by this stirring operation, air (bubbles) mixed in the sub ink tank ST before stirring flows out from the sub ink tank ST and then flows into the sub ink tank ST again.

  As described above, in the present embodiment, unlike the comparative example described above, air is sent back to the sub ink tank ST by such an ink agitation operation, and therefore remains in the first ink supply tube 36. Air (bubbles) can be reduced. Therefore, even when the ink in the sub ink tank ST flows through the first ink supply tube 36 and is replenished to the head unit 30 (head 31), air (bubbles) flowing toward the head side by being pushed by the ink flow is reduced. Therefore, it is possible to prevent air (bubbles) from being mixed when ink is supplied to the head unit 30.

<<< Effectiveness of Printer 1 According to the Present Embodiment >>>
As described above, the printer 1 according to the present embodiment stores the head unit 30 that discharges ink onto the roll paper 2, the sub ink tank ST that stores ink, and the ink that is sent from the sub ink tank ST. The preliminary ink tank SST used for sending back to the ink tank ST, the first ink supply tube 36 for communicating the sub ink tank ST and the head unit 30, and the first ink supply tube 36 and the preliminary ink tank SST are communicated. A second ink supply tube 37, a third ink supply tube 38 for communicating the spare ink tank SST and the second ink supply tube 37, a first ink supply tube 36 and a second ink supply tube 37 from the sub ink tank ST. The ink is preliminarily introduced by flowing the ink through The ink is stored in the tank SST, and the ink is allowed to flow from the spare ink tank SST through the third ink supply tube 38, the second ink supply tube 37, and the first ink supply tube 36, thereby allowing the ink to flow into the sub ink tank ST. And a supply pump P to be accommodated.

  In the comparative example, when the ink stirring operation is performed, the first ink supply tube 36 that is used in the forward path when ink is sent from the sub ink tank ST to the spare ink tank SST, and the ink from the spare ink tank SST to the sub ink tank ST The first ink supply tube 36 used in the return path when returning the ink is made different. For this reason, when air is mixed into the sub ink tank ST, if the ink is agitated by reciprocating the ink between the sub ink tank ST and the spare ink tank SST, the air is supplied to the first ink supply tube 36. (Bubbles) remain. After this stirring operation, if the ink in the sub ink tank ST is caused to flow through the first ink supply tube 36 to replenish the head unit 30, the air (bubbles) remaining in the first ink supply tube 36 becomes the head unit 30. By reaching (head 31), when the head unit 30 ejects ink, ejection failure may occur, leading to deterioration of the printed image.

  In contrast, in the present embodiment, when the ink stirring operation is performed, the first ink supply tube 36 used in the forward path when the ink is sent from the sub ink tank ST to the spare ink tank SST, and the spare ink tank SST are used. The first ink supply tube 36 used in the return path when returning ink to the sub ink tank ST is shared. As a result, when air is mixed into the sub ink tank ST, even if the ink stirring operation is performed, unlike the comparative example, air (bubbles) is sent back to the sub ink tank ST. The air (bubbles) remaining in one ink supply tube 36 can be reduced. Therefore, after this stirring operation, it is possible to suppress air (bubbles) from being mixed when ink is supplied to the head unit 30.

=== Other Embodiments ===
Although this embodiment mainly describes the liquid ejection device, disclosure of a liquid stirring method and the like is also included. Further, the present embodiment is intended to facilitate understanding of the present invention and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<Liquid ejection device>
In the above embodiment, the ink jet printer has been described as an example of the liquid ejection device, but the present invention is not limited to this. For example, a liquid ejection device that ejects liquid other than ink may be used. The present invention can be used for various liquid ejection devices including a liquid ejecting head that ejects a minute amount of liquid droplets. In addition, a droplet means the state of the liquid discharged from the said liquid discharge apparatus, and also includes what pulls a tail in granular shape, tear shape, and a thread form. The liquid here may be any material that can be discharged by the liquid discharge device. For example, it may be in a state in which the substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ) And a liquid as one state of a substance, as well as a material in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed or mixed in a solvent. Further, representative examples of the liquid include ink and liquid crystal as described in the above embodiment. Here, the ink includes general water-based inks and oil-based inks, and various liquid compositions such as gel inks and hot melt inks. As a specific example of the liquid ejection device, for example, a liquid containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, a color filter or the like in a dispersed or dissolved form. It may be a liquid ejecting apparatus for ejecting, a liquid ejecting apparatus for ejecting a bio-organic material used for biochip manufacturing, a liquid ejecting apparatus for ejecting liquid as a sample used as a precision pipette, a textile printing apparatus, a microdispenser, or the like. In addition, a transparent resin liquid such as UV curable resin is used to form a liquid ejection device that ejects lubricating oil pinpoint to precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. A liquid discharge apparatus that discharges an acid or alkali or the like to etch the substrate or the like may be employed. The present invention can be applied to any one of these liquid ejection devices.

1 Liquid ejection device, 2 roll paper,
10 feeding unit, 18 roll paper reel,
19 relay roller, 20 transport unit,
21 relay roller, 22 relay roller,
23 1st conveyance roller, 24 2nd conveyance roller,
25 reversing roller, 26 relay roller,
27 feed roller, 29 platen,
30 head units, 31 heads,
34 ink supply tube, 35 ink supply unit,
36 first ink supply tube, 36V valve,
37 Second ink supply tube, 37V valve,
38 Third ink supply tube, 38V valve,
40 Carriage unit, 41 Guide rail,
42 Carriage, 45 Cleaning unit,
50 detector groups, 60 controllers,
70 heater unit, 80 air blow unit,
81 fans, 90 winding units,
91 relay roller, 92 roll paper winding drive shaft,
110 computers,
IC ink cartridge, ST sub ink tank,
SST spare ink tank, P supply pump

Claims (2)

A head unit for discharging liquid onto a medium;
A first liquid storage section for storing a liquid;
A second liquid container used to store the liquid sent out from the first liquid container and send it back to the first liquid container;
A first flow path for communicating the first liquid storage portion and the head portion;
A second flow path for communicating the first flow path with the second liquid storage portion;
A third flow path for communicating the second liquid storage portion and the second flow path;
By flowing a liquid from the first liquid storage portion via the first flow path and the second flow path, the liquid is stored in the second liquid storage section, and the first liquid storage section A liquid supply section for storing the liquid in the first liquid storage section by flowing the liquid through the three flow paths, the second flow path, and the first flow path;
A liquid ejecting apparatus comprising: A first flow path that communicates the first liquid storage section with a head section that discharges liquid to the medium, and a first flow path that is fed from the first flow path and the first liquid storage section. The liquid is allowed to flow through a second flow path that communicates with the second liquid storage unit used to store the liquid and send it back to the first liquid storage unit. To contain,
By flowing the liquid from the second liquid storage part via the third flow path that connects the second liquid storage part and the second flow path, the second flow path, and the first flow path, Storing liquid in the first liquid storage portion;
A liquid stirring method characterized by comprising: