JP2012176626A - Liquid ejecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejecting apparatus which can prevent air bubbles contained in liquid in a switching device from being discharged from a liquid ejecting head, when the liquid is ejected to a target from the liquid ejecting head.SOLUTION: An inkjet printer includes, in the switching device 25: a first connecting path 44 for feeding a photo black ink; a second connecting path 45 for feeding a mat black ink; a first through-hole for communicating between the junction of the downstream ends of the first connecting path 44 and the second connecting path 45 and a recording head side; a first on-off valve for opening and closing the first connecting path 44; and a second on-off valve for opening and closing the second connecting path 45. The first connecting path 44 and the second connecting path 45 include a first communicating groove 37 and a second communicating groove 38, respectively. At positions on the intermediate of the first communicating groove 37 and the second communicating groove 38, air-bulb staying parts 62 are provided which allow a stay of the air bulbs contained in the photo black ink and the mat black ink flowing therein.

Description

  The present invention relates to a liquid ejecting apparatus such as an ink jet printer.

  In general, ink jet printers (hereinafter referred to as “printers”) are widely known as liquid ejecting apparatuses that eject liquid onto a target. This printer supplies ink from an ink cartridge that contains ink to a recording head (liquid ejecting head) that ejects ink (liquid), and records the ink as a target from nozzles formed on the nozzle formation surface of the recording head. Printing is performed by spraying on paper. In such a printer, when an ink cartridge is disposed at a position away from the recording head, ink is supplied to the recording head side through a tube drawn from the ink cartridge into the printer. Yes.

  By the way, when changing the ink ejected from the nozzle of the recording head to another type of ink, first, the supply of ink from the ink cartridge that has been used until then is stopped, and from this state, Residual ink is discharged through the nozzles of the recording head. Then, after the inside of the tube is cleaned by discharging the residual ink, the other type of ink is supplied to the recording head side through the tube from an ink cartridge containing another type of ink.

  For this reason, when the type of ink ejected from the nozzles of the recording head is changed in this way, the ink before the change remaining in the tube must be sucked and discharged, resulting in increased waste of ink. There was a problem. Therefore, in order to cope with such a problem, conventionally, there has been proposed a printer provided with an ink switching device connected to each ink cartridge via a tube corresponding to each ink cartridge in the vicinity of the recording head (for example, Patent Document 1).

  In the printer of Patent Document 1, the type of ink supplied to the recording head can be switched between the first type ink (first liquid) and the second type ink (second liquid) in the switching device. It has become. That is, in the switching device, the downstream end of the first passage portion (first supply passage) that supplies the first type of ink and the downstream end of the second passage portion (second supply passage) that supplies the second type of ink. Are joined, and the joining point and the recording head are connected by a head side supply path for supplying ink to the recording head. Furthermore, in this switching device, a first diaphragm (first on-off valve) for opening and closing the first passage portion and a second diaphragm (second on-off valve) for opening and closing the second passage portion are provided, The supply state of the first type ink and the second type ink is switched by opening the other diaphragm and closing the other diaphragm.

  That is, in this switching device, when supplying the first type of ink to the recording head, the first diaphragm of the first passage portion is opened and the second diaphragm of the second passage portion is closed. On the other hand, when supplying the second type of ink to the recording head, the second diaphragm of the second passage portion is opened and the first diaphragm of the first passage portion is closed.

JP 2006-175626 A

  By the way, in the printer of Patent Document 1, when bubbles are mixed in the first type of ink and the second type of ink in the first passage unit and the second passage unit in the switching device, the print head is Since bubbles are discharged together with ink from the nozzle opening row, there is a problem that printing defects such as missing dots occur.

  The present invention has been made paying attention to such problems existing in the prior art. The purpose is to provide a liquid that can prevent bubbles contained in the liquid in the switching device from being discharged from the liquid ejecting head when the liquid is ejected from the liquid ejecting head to the target. It is in providing an injection device.

  In order to achieve the above object, a liquid ejecting apparatus according to an aspect of the invention includes a liquid ejecting head that ejects liquid onto a target, and the types of liquid supplied to the liquid ejecting head are the first liquid and the first liquid. Is a liquid ejecting apparatus including a switching device that selectively switches between different second liquids, and in the switching device, a first supply path that supplies the first liquid, and the second liquid A second supply path for supplying liquid, a head-side supply path communicating between the first supply path and a confluence of downstream ends of the second supply path and the liquid jet head, and the first supply path A first on-off valve that opens and closes the first supply path upstream from the junction with the second supply path; and the first on-off valve upstream of the junction with the first supply path in the second supply path. A second on-off valve that opens and closes the supply path, In the middle position of the supply passage and the second supply path, a bubble trapping portion for permitting the retention of air bubbles contained in the first liquid and the second liquid are provided, respectively.

  According to the present invention, since the bubbles contained in the first liquid and the second liquid in the switching device are retained in the bubble retaining portion, the first liquid or the second liquid is ejected from the liquid ejecting head to the target. At this time, it is possible to prevent the liquid mixed with bubbles from being discharged from the liquid ejecting head.

  In the liquid ejecting apparatus according to the aspect of the invention, a bubble guide channel portion in which the channel shape extends with a height difference is provided at a midway position of the first supply channel and the second supply channel. The bubble retention part is provided at a high position in the flow path part.

  According to the present invention, it is possible to collect the bubbles in the bubble guide channel portion in the bubble retention portion at a high position, and it is possible to retain the collected bubbles without flowing in the bubble retention portion.

In the liquid jet apparatus according to the aspect of the invention, in the bubble guide channel portion, a downstream nearest portion of the bubble retention portion extends in a direction lower than the bubble retention portion.
When bubbles are present in the liquid on the downstream side that is closer to the liquid ejecting head than the bubble retaining portion in the bubble guiding channel, the bubbles are directed from the liquid ejecting head to the first liquid or the second liquid. There is a possibility of flowing toward the liquid jet head due to the negative pressure generated when jetting. In this respect, according to the present invention, in the bubble induction flow path portion, the downstream nearest portion of the bubble retention portion extends in a direction lower than the bubble retention portion, and thus is located at a position higher than the downstream portion. Since it moves quickly to a certain bubble retention part by its own buoyancy and stays in the bubble retention part, it is possible to eliminate the possibility that liquid mixed with bubbles is ejected from the liquid ejection head.

  In the liquid ejecting apparatus according to the aspect of the invention, the bubble guiding channel portion is present in the bubble guiding channel portion when the first liquid and the second liquid in the bubble guiding channel portion are not flowing. The part connected to the bubble retention part extends obliquely or curved so that the bubble can move to the bubble retention part side by its buoyancy.

  According to the present invention, the bubbles existing in the bubble guiding channel portion move toward the bubble retaining portion by their own buoyancy, and therefore, the bubbles are prevented from staying in the portion other than the bubble retaining portion in the bubble guiding channel portion. It becomes possible to do.

  In the liquid ejecting apparatus according to the aspect of the invention, the bubble guiding channel portion may be configured to eject the first liquid or the second liquid in the bubble guiding channel unit as the first liquid or the second liquid is ejected from the liquid ejecting head. When two liquids flow, the length downstream of the bubble retention portion is set so that the bubbles existing in the bubble induction channel portion remain in the bubble induction channel portion by their buoyancy. ing.

  According to the present invention, when the first liquid or the second liquid is ejected from the liquid ejecting head, the bubbles existing in the bubble guiding flow path portion remain in the bubble guiding flow path portion, so that the bubbles are mixed from the liquid ejecting head. It is possible to suppress the ejection of the liquid.

  In the liquid ejecting apparatus according to the aspect of the invention, when the first liquid or the second liquid in the bubble guiding channel portion flows along with the suction from the liquid ejecting head, To the extent that the bubbles existing in the bubble induction flow path section flow downstream from the bubble induction flow path section and are discharged from the liquid ejecting head against the buoyancy of the bubble induction flow path section. The length of is set.

  According to the present invention, when the first liquid or the second liquid is sucked from the liquid ejecting head, the bubbles existing in the bubble guide channel portion are on the downstream side of the bubble guide channel portion against its own buoyancy. And discharged from the liquid ejecting head. For this reason, by sucking the first liquid or the second liquid from the liquid ejecting head, it is possible to reliably remove the air bubbles present in the air bubble guiding channel.

In the liquid ejecting apparatus according to the aspect of the invention, the bubble guide channel portion may be formed along a vertical plane.
According to the present invention, the bubble guide channel portion can be formed in a narrow space, and the size of the liquid ejecting apparatus can be suppressed without increasing the switching device.

FIG. 2 is a schematic plan view of the ink jet printer according to the embodiment. The front simplified view of the carriage of the printer. The disassembled perspective view of the switching apparatus of the printer. The principal part perspective view of the switching apparatus of the printer. The principal part expanded sectional view of the connection part of a switching apparatus. The top view of a switching apparatus. Sectional drawing of the principal part of a switching apparatus. The perspective view of a transmission member. The side view of a switching apparatus. The principal part expanded sectional view of the switching apparatus of the state which the 1st on-off valve opened and the 2nd on-off valve closed. The principal part expanded sectional view of the switching apparatus of the state which the 1st on-off valve closed and the 2nd on-off valve opened. (A)-(e) is the simplified diagram which shows the example of a change of a 1st communication groove and a 2nd communication groove. The simplified diagram which shows the other example of a change of a 1st communication groove | channel and a 2nd communication groove | channel.

  Hereinafter, an embodiment in which the present invention is embodied in an ink jet printer and an ink cartridge mounted on the printer will be described with reference to the drawings. In the following description, “front-rear direction”, “left-right direction”, and “up-down direction” indicate the front-rear direction, left-right direction, and up-down direction indicated by arrows in FIG.

  As shown in FIG. 1, an ink jet printer 11 as a liquid ejecting apparatus includes a main body frame 12 having a rectangular shape in a plan view, and a platen 13 is disposed in the main body frame 12 along a left-right direction that is a main scanning direction. It is provided to extend. On the platen 13, a recording sheet P as a target is fed along a front-rear direction that is a sub-scanning direction by a paper feeding mechanism (not shown). A rod-shaped guide shaft 14 extending in parallel with the longitudinal direction (left-right direction) of the platen 13 is installed above the platen 13 in the main body frame 12.

  A carriage 15 is supported on the guide shaft 14 in a state where the carriage 15 can reciprocate in the axial direction (left-right direction) of the guide shaft 14. The carriage 15 is connected to a carriage motor 17 provided on the back surface of the main body frame 12 via an endless timing belt 16 stretched between a pair of pulleys 16 a provided on the inner surface of the rear wall of the main body frame 12. Yes. Therefore, the carriage 15 is reciprocated along the guide shaft 14 by driving the carriage motor 17.

  As shown in FIGS. 1 and 2, a recording head 18 as a liquid ejecting head is mounted on the surface of the carriage 15 that faces the platen 13. On the carriage 15, a plurality (four in this embodiment) of valve units 19 a to 19 d for supplying ink as temporarily stored liquid to the recording head 18 are provided. A plurality (three in this embodiment) of nozzles 20a to 20c are formed on the lower surface of the recording head 18, and ink droplets are applied to the recording paper P fed from the nozzles 20a to 20c onto the platen 13. Printing is performed by being ejected.

  A cartridge holder 21 is provided at the right end in the main body frame 12, and a plurality (four in this embodiment) of ink cartridges 22 a to 22 d that contain different types of ink are respectively stored in the cartridge holder 21. It is attached detachably. The cartridge holder 21 is connected to the valve units 19a to 19d on the carriage 15 via ink supply tubes 24a to 24d, respectively. When the ink cartridges 22a to 22d are attached to the cartridge holder 21, the ink cartridges 22a to 22d communicate with the valve units 19a to 19d via the ink supply tubes 24a to 24d, respectively. .

  The ink cartridge 22a and the ink cartridge 22b contain photo black ink as the first liquid and mat black ink as the second liquid, respectively. Accordingly, photo black ink is temporarily stored in the valve unit 19a, and mat black ink is temporarily stored in the valve unit 19b.

  In this case, the photo black ink is suitable for printing when the recording paper P is a glossy paper, and the mat black ink is suitable for printing when the recording paper P is a mat paper. Therefore, between the valve units 19a and 19b on the carriage 15 and the recording head 18, the ink supplied from the both valve units 19a and 19b to the recording head 18 is either photo black ink or matte black ink. A switching device 25 is provided for switching between the two. That is, the switching device 25 determines the ink ejected from the nozzles 20a of the recording head 18 between the photo black ink and the matte black ink depending on, for example, whether the recording paper P is a glossy paper or a matte paper. Switchable.

  A maintenance unit 26 for performing maintenance such as cleaning of the recording head 18 is disposed at a position near the right end in the main body frame 12 and at the home position of the carriage 15. The maintenance unit 26 is a cap for sealing the nozzle forming surface 18a where the nozzles 20a to 20c of the recording head 18 are open and receiving ink discharged from the nozzles 20a to 20c by flushing. 27 and a suction pump (not shown) capable of sucking the inside of the cap 27.

  Then, by sucking the inside of the cap 27 with a suction pump while the nozzle forming surface 18a of the recording head 18 is sealed by the cap 27, the thickened ink in the recording head 18 is transferred from the nozzles 20a to 20c into the cap 27. So-called cleaning is performed.

Next, the configuration of the switching device 25 will be described in detail.
As shown in FIGS. 3 to 5, the switching device 25 includes a main body 30 having a substantially symmetric block shape, and the upper surface of the main body 30 is paired with a predetermined interval in the left-right direction. A first connection pipe 31 and a second connection pipe 32 are erected. The first connection pipe 31 is connected to the valve unit 19a, and the second connection pipe 32 is connected to the valve unit 19b. A bottomed cylindrical first valve body housing portion 33 opened on the left side is provided on the front side of the first connection pipe 31, and a bottomed cylindrical second opening opened on the right side on the front side of the second connection pipe 32. A valve body accommodating portion 34 is provided.

  The first valve body housing portion 33 and the second valve body housing portion 34 are connected via a connecting portion 35. A connecting path 36 that extends linearly in the left-right direction (horizontal direction) is formed in the connecting section 35, and the first valve body storage section 33 and the second valve body storage section 34 are connected via the connection path 36. These central portions communicate with each other. That is, the connection path 36 is opened in the center part of the 1st valve body accommodating part 33 and the 2nd valve body accommodating part 34, respectively.

  Further, the main body 30 is formed with a first communication groove 37 as a bubble guiding channel portion that communicates the first connecting pipe 31 and the first valve body housing portion 33. That is, the base end of the first communication groove 37 is connected to the first connection pipe 31, on the left surface of the main body 30, on the inner peripheral surface 33 a of the first valve body housing portion 33, and on the first valve body housing portion 33. The connection path 36 on the inner bottom surface 33b extends from the upper side to the front side through the inner bottom surface 33b, and the tip of the connection path 36 reaches the obliquely lower front side of the connection path 36 on the inner bottom surface 33b. An annular first protrusion 33 c is formed on the inner bottom surface 33 b of the first valve body housing portion 33 so as to surround the connection path 36.

  Similarly to the first communication groove 37, the main body 30 is formed with a second communication groove 38 that communicates the second connection pipe 32 and the second valve body housing portion 34. That is, the base end of the second communication groove 38 is connected to the second connecting pipe 32, the right side surface of the main body 30, the inner peripheral surface 34 a of the second valve body housing portion 34, and the second valve body housing portion 34. The connecting path 36 on the inner bottom face 34b extends from the upper side to the front side through the inner bottom face 34b, and the tip of the connecting path 36 reaches the diagonally lower front side of the connecting path 36 on the inner bottom face 34b. On the inner bottom surface 34 b of the second valve element housing portion 34, an annular second protrusion 34 c is formed so as to surround the connection path 36.

  As shown in FIGS. 5 and 6, the front end in the center of the connecting path 36 in the left-right direction is at the front end in the groove 40 formed in the connecting path 36 and on the upper surface of the connecting portion 35 and extending in the front-rear direction. A first through hole 39 communicating with the portion is formed. On the other hand, a second through hole 41 communicating with the recording head 18 (see FIG. 2) is formed at the rear end portion in the concave groove 40. A sealing member (not shown) that seals the upper end opening of the groove 40 is disposed on the upper surface of the connecting portion 35. In the present embodiment, the first through hole 39, the recessed groove 40, and the second through hole 41 constitute a head side supply path.

  As shown in FIG. 5, in the connection path 36, the left part from the center in the left-right direction is the first connection path 44, and the right part from the center in the left-right direction is the second connection path 45. Accordingly, the central portion of the connection path 36 is a junction point G between the first connection path 44 and the second connection path 45, and at the junction point G, the first connection path 44, the second connection path 45, and the The 1 through holes 39 communicate with each other. In the present embodiment, a first supply path is constituted by the first communication groove 37 (see FIG. 4), the first valve body housing portion 33, and the first connection path 44, and the second communication groove 38, A second supply path is configured by the second valve body accommodating portion 34 and the second connection path 45. In addition, the enlarged diameter part 36a whose diameter is wider than a center part is provided in the both ends (the left end part of the 1st connection path 44, and the right end part of the 2nd connection path 45) of the connection path 36.

  As shown in FIG. 7, a substantially cylindrical transmission member 46 is accommodated in the first connection path 44 and the second connection path 45 so as to be slidable in the left-right direction. Here, as shown in FIG. 8, the transmission member 46 includes a columnar small-diameter portion 46a and a large-diameter portion 46b in which one end of the small-diameter portion 46a is larger in diameter than the small-diameter portion 46a. ing. The large-diameter portion 46b is formed with a notch 46c having the same diameter as the small-diameter portion 46a by the amount rotated about 90 degrees about the axial direction of the transmission member 46.

  3 and FIG. 7, one of the two transmission members 46 is inserted into the first connecting path 44 from the small diameter portion 46a side, and the other transmission member 46 is inserted into the small diameter portion 46a. The transmission member 46 is accommodated in the first connection path 44 and the second connection path 45 by being inserted into the second connection path 45 from the 46a side. In this case, the notches 46 c of both transmission members 46 face downward, and the large diameter portions 46 b of both transmission members 46 are respectively accommodated in the enlarged diameter portions 36 a of the connection path 36. Further, the end surfaces on the small diameter portion 46 a side of both transmission members 46 are in contact with each other at the center portion in the left-right direction of the connection path 36. The sum of the lengths of the two transmission members 46 in the longitudinal direction is slightly longer than the length of the connecting path 36 in the left-right direction.

  In the first valve body housing portion 33 and the second valve body housing portion 34, a disk-like first opening / closing valve 47 having flexibility and a second opening / closing valve 48 having the same configuration as the first opening / closing valve 47 are provided. Each is housed. A circular first concave portion 47a and a second concave portion 48a are provided at the outer central portions of the first on-off valve 47 and the second on-off valve 48, respectively. In the 1st recessed part 47a and the 2nd recessed part 48a, the disk-shaped 1st relay member 49 and the 2nd relay member 50 which have rigidity are accommodated, respectively.

  In this case, the first recess 47a and the second recess 48a have the same configuration, and the first relay member 49 and the second relay member 50 have the same configuration. A flexible film (not shown) is attached to the left surface of the main body 30 so as to seal the opening of the first valve body housing portion 33 and the opening of the first communication groove 37, and A flexible film (not shown) is attached so as to seal the opening of the second valve body accommodating portion 34 and the opening of the second communication groove 38.

Next, the configuration of the first communication groove 37 as the above-described bubble guiding channel portion will be described in detail.
As shown in FIG. 9, the first communication groove 37 is slanted straight on the inner bottom surface 33 b, which is a vertical plane in the first valve body housing portion 33, so as to rise frontward from the rear oblique upper part to the upper part. A straight portion 60 that extends and a curved portion 61 that extends downward while curving in a substantially spiral shape so as to draw an arc that swells forward from the upper portion are provided. The straight portion 60 and the curved portion 61 are connected at the upper portion on the inner bottom surface 33 b, and the connecting portion between the curved portion 61 and the straight portion 60 is a bubble retention portion 62. In this case, the bubble retention part 62 is a part located at the highest position in the first communication groove 37 in the first valve body housing part 33. That is, in the first communication groove 37, the bubble retention part 62 is located at a position higher than the nearest part on the downstream side of the bubble retention part 62.

  In addition, the lower end (tip) of the curved portion 61 in the first communication groove 37 reaches the obliquely lower front side of the connection path 36 and is adjacent to the first protrusion 33 c. When the photo black ink in the first communication groove 37 is not flowing, the bending portion 61 can move the bubbles present in the photo black ink in the bending portion 61 to the bubble retention portion 62 by its own buoyancy. It is curved to some extent.

  Therefore, when the photo black ink in the first communication groove 37 does not flow, all the bubbles in the first communication groove 37 including the air bubbles present at the lower end portion of the curved portion 61 are smoothly caused by the buoyancy of the bubbles. It moves to 62. Similarly, the bubbles present in the ink in the straight portion 60 also extend straightly and obliquely toward the bubble retention portion 62, so that the bubbles stay in the bubble retention portion 62 smoothly by the buoyancy of the bubbles themselves. Moving.

  The second communication groove 38, which also functions as the bubble guide channel, has the same configuration as the first communication groove 37 detailed in the above-described manner. Omitted.

Next, the operation of the switching device 25 will be described.
10 and 11 are cross-sectional views of the main body 30 when viewed from the lower side in the vicinity of the connecting portion 35 and the connecting portion 35.

  As shown in FIG. 10, when the ink supplied to the recording head 18 is switched from the matte black ink to the photo black ink, first, the second opening / closing valve 48 is moved leftward (horizontal) via the second relay member 50. Direction). Then, the second on-off valve 48 comes into close contact with the second protrusion 34c, and the first on-off valve 47 is pressed toward the left via both the transmission members 46, and the first on-off valve 47 and the first protrusion 33c Are separated. In this state, the first communication groove 37 and the first connection path 44 are in communication with each other through the first valve body housing portion 33, and the second connection groove 38 and the second connection path 45 are in non-communication. That is, the first on-off valve 47 is opened and the second on-off valve 48 is closed (the state shown in FIG. 10).

  In this state, when mat black ink, which has been used previously, is ejected from the nozzle 20a of the recording head 18 into the cap 27 by flushing, the photo black ink passes through the first valve body accommodating portion 33 from the first communication groove 37. Into the first connecting path 44. In the flushing in this case, ink is selectively ejected only from the nozzles 20a. 10, the photo black ink that has flowed into the first connection path 44 flows into the first through hole 39, and the ink supplied to the recording head 18 is transferred from the mat black ink. Switch to photo black ink.

  On the other hand, as shown in FIG. 11, when the ink to be supplied to the recording head 18 is switched from photo black ink to matte black ink, first, the first on-off valve 47 is moved to the right (horizontal) via the first relay member 49. Direction). Then, the first on-off valve 47 is in close contact with the first protrusion 33c, and the second on-off valve 48 is pressed rightward through the two transmission members 46, and the second on-off valve 48 and the second protrusion 34c Are separated. In this state, the second communication groove 38 and the second connection path 45 are in communication with each other through the second valve body housing portion 34, and the first communication groove 37 and the first connection path 44 are in non-communication. That is, the first on-off valve 47 is closed and the second on-off valve 48 is opened (the state shown in FIG. 11).

  In this state, when the photo black ink, which has been used last time, is ejected from the nozzle 20a of the recording head 18 into the cap 27 by flushing, the mat black ink passes through the second connecting groove 38 into the second valve body accommodating portion 34. Into the second connecting path 45. In the flushing in this case, ink is selectively ejected only from the nozzles 20a. Then, as indicated by an arrow in FIG. 11, the matte black ink that has flowed into the second connection path 45 flows into the first through hole 39, and the ink supplied to the recording head 18 is removed from the photoblack ink. Switch to matte black ink.

Next, the operation of the first communication groove 37 will be described.
(When cleaning)
When the recording head 18 is cleaned, the photo black ink is forcibly sucked into the cap 27 and discharged from the nozzle 20a. Due to the suction force from the nozzle 20a at this time, the photo black ink in the first communication groove 37 also flows sequentially from the connecting path 36 toward the recording head 18 and is discharged from the nozzle 20a into the cap 27.

  In this case, the bubbles staying in the bubble staying part 62 try to stay in the bubble staying part 62 due to their own buoyancy, but the suction force from the nozzle 20a (suction from the nozzle 20a) rather than the buoyancy of the bubble. The flow rate of the photo black ink in the first communication groove 37 generated by the above becomes larger. For this reason, the air bubbles staying in the air bubble retention portion 62 are promptly moved from the curved portion 61 having a smoothly curved flow path shape to the downstream side with the photo black ink from the air bubble retention portion 62 to the connection passage 36 side. And is discharged from the nozzle 20a into the cap 27.

  It should be noted that the first communication groove 37 has air bubbles present in the first communication groove 37 when the photo black ink in the first communication groove 37 flows with suction from the recording head 18 during cleaning. The length of the downstream side (curved portion 61) from the bubble retention portion 62 is set to such an extent that the liquid flows downstream from the first communication groove 37 against the buoyancy and is discharged from the recording head 18. ing. This also applies to the second communication groove 38.

(When printing)
At the time of printing, photo black ink is ejected from the nozzles 20a of the recording head 18 onto the recording paper P, and with this ejection, the photo black ink in the first communication groove 37 also sequentially moves from the connecting path 36 toward the recording head 18 side. It flows and is injected from the nozzle 20a. In this case, the buoyancy of the bubbles staying in the bubble retaining portion 62 is the negative pressure generated by the ejection of the photo black ink from the nozzle 20a (the first communication groove 37 generated by the ejection of the photo black ink from the nozzle 20a. The flow rate of the photo black ink inside).

  For this reason, even if the photo black ink in the first communication groove 37 flows from the connection path 36 toward the recording head 18, the bubbles staying in the bubble staying portion 62 continue to stay in the bubble staying portion 62. Therefore, during printing, it is difficult for ink mixed with air bubbles to be ejected from the nozzles 20a of the recording head 18, so that occurrence of printing defects such as missing dots is suppressed.

  Further, flushing is performed periodically during printing, and the negative pressure generated by flushing from the nozzle 20a (the flow rate of the photo black ink in the first communication groove 37 generated by the jet of photo black ink) is also generated. Since it is almost the same as that at the time of printing, as in the case of printing, the ink mixed with bubbles is suppressed from being ejected from the nozzles 20a of the recording head 18 at the time of flushing.

  The first communication groove 37 is formed in the first communication groove 37 when the photo black ink in the first communication groove 37 flows as the photo black ink is ejected from the recording head 18 during printing. The length on the downstream side (curved portion 61) from the bubble retaining portion 62 is set to such an extent that the bubbles existing in the first retaining groove 37 remain in the first communication groove 37 by their own buoyancy. This also applies to the second communication groove 38.

(When printing is suspended)
Since the photo black ink in the first communication groove 37 does not flow when printing is suspended, the bubbles staying in the bubble retention portion 62 continue to stay in the bubble retention portion 62 due to their own buoyancy. In this case, micro bubbles may remain particularly at the lower end portion of the bending portion 61, but the micro bubbles move to the bubble retention portion 62 due to their own buoyancy due to the flow path shape of the bending portion 61. For this reason, in the next printing, it is suppressed that the ink mixed with such microbubbles is ejected from the nozzle 20a.

In addition, since the effect | action in the 2nd communication groove 38 is the same as the effect | action of the above-mentioned 1st communication groove 37, description of the effect | action is abbreviate | omitted.
As described above, according to the embodiment described in detail, the following effects can be obtained.

  (1) When printing is performed by ejecting photo black ink or matte black ink from the nozzle 20a of the recording head 18 onto the recording paper P, it is included in the photo black ink and the matte black ink in the switching device 25. Bubbles stay in the bubble retention part 62. For this reason, since it is possible to suppress ejection of ink mixed with bubbles from the nozzle 20a during printing, it is possible to suppress the occurrence of printing defects such as missing dots.

  (2) For the air bubbles that have gathered and stayed in the bubble retention portion 62 from a position lower than the bubble retention portion 62 by buoyancy, the recording head 18 is cleaned, whereby the first communication groove 37 and the second communication groove. 38 can be sucked and discharged from the nozzle 20a together with the photo black ink and the matte black ink flowing through 38 respectively.

  (3) The first communication groove 37 and the second communication groove 38 are provided so as to extend along the inner bottom surfaces 33b and 34b, which are vertical planes, in the valve body accommodating portions 33 and 34, respectively. The bubble retention part 62 is configured by a part of the 37 and the second communication groove 38. For this reason, the 1st communication groove 37 and the 2nd communication groove 38 containing the bubble retention part 62 can be formed in a narrow space in the horizontal direction, and it contributes to suppression of the enlargement of the switching device 25 and the inkjet printer 11. it can.

  (4) In the first communication groove 37 and the second communication groove 38, the bubble retention part 62 is located at a position higher than the downstream nearest part of the bubble retention part 62. For this reason, at the time of printing, the bubbles existing on the downstream side of the bubble retention portion 62 are moved and retained in the bubble retention portion 62 by their own buoyancy, so that bubbles are mixed from the nozzle 20a of the recording head 18. Ink can be made difficult to be discharged.

  (5) The curved portion 61 in the first communication groove 37 and the second communication groove 38 particularly has a curved portion 61 at the time of a printing pause when the photo black ink and the mat black ink in the first communication groove 37 and the second communication groove 38 are not flowing. The bubbles existing in the curved portion 61 extend in a curved shape so that the bubbles can move to the bubble retaining portion 62 by their buoyancy. For this reason, since the bubble which exists in the bending part 61 moves to the bubble retention part 62 with its own buoyancy, it can suppress that a bubble retains in parts other than the bubble retention part 62 in the bending part 61. FIG. In this case, in particular, by suppressing the microbubbles from remaining at the lower end portion (downstream end portion) of the curved portion 61, the ink mixed with the microbubbles flows to the recording head 18 side during the next printing and flows from the nozzle 20a. Injecting can be suppressed.

  (6) The first communication groove 37 and the second communication groove 38 are formed in the first communication groove 37 and the second communication groove 38 by the buoyancy of the bubbles existing in the first communication groove 37 and the second communication groove 38 during printing. The lengths of the downstream side (curved portion 61) from the bubble retaining portion 62 are set to such an extent that they remain in the communication groove 38. For this reason, when the photo black ink or the matte black ink is ejected from the recording head 18 during printing, the bubbles existing in the first communication groove 37 or the second communication groove 38 are removed from the first communication groove 37 or the second communication groove. It can be retained in the groove 38. Accordingly, it is possible to prevent the photo black ink or matte black ink mixed with bubbles from being ejected from the recording head 18.

  (7) The first communication groove 37 and the second communication groove 38 are bubbles present in the first communication groove 37 and the second communication groove 38 when the recording head 18 is cleaned (at the time of suction from the recording head 18). Against the buoyancy of itself, the downstream side (curved part 61) from the bubble retaining part 62 to the extent that it flows downstream from the first connecting groove 37 and the second connecting groove 38 and is discharged from the recording head 18. The length of is set. For this reason, when the photo black ink or the mat black ink is sucked from the recording head 18 at the time of cleaning, the bubbles present in the first communication groove 37 or the second communication groove 38 are removed together with the photo black ink or the mat black ink. It is possible to flow downstream from the first communication groove 37 or the second communication groove 38 and eject the recording head 18. As a result, the bubbles present in the first communication groove 37 and the second communication groove 38 can be reliably removed.

  (8) When the ink supplied to the recording head 18 by the switching device 25 is switched between the photo black ink and the mat black ink, the first valve body accommodating portion 33 or the second valve is opened from the opening of the connection path 36. Matt black ink or photo black ink used before switching may be mixed in the body accommodating portion 34. In this regard, in the present embodiment, the curved portions 61 of the first communication groove 37 and the second communication groove 38 are formed on the inner bottom surface 33 b in the first valve body housing portion 33 and the inner bottom surface of the second valve body housing portion 34. On 34b, it extends so that it may approach the opening of the connection path 36 located in the center part, curving in a substantially spiral shape. For this reason, the old matte black ink before switching mixed in the first valve body housing portion 33 is collected at the opening of the connecting path 36 so as to be swirled by the flow of new photoblack ink after switching that flows through the curved portion 61. And discharged from the opening. On the other hand, the old photoblack ink before switching mixed in the second valve body accommodating portion 34 is collected at the opening of the connecting path 36 so as to be swirled by the flow of new matte black ink after switching flowing through the curved portion 61. And discharged from the opening. Therefore, the old matte black ink mixed in the first valve body housing portion 33 and the old photo black ink mixed in the second valve body housing portion 34 are respectively connected to the connecting path 36 by the action of the substantially spiral curved portion 61. Can be smoothly discharged from the opening.

  (9) Since the ink switching between the mat black ink and the photo black ink is performed by flushing in which the ink is selectively ejected only from the nozzle 20a, the mat black ink and the photo black ink are switched during the ink switching. It is possible to prevent the consumption of ink other than. Incidentally, when the ink is switched between the matte black ink and the photoblack ink by cleaning using the integral cap 27 that collectively covers all the nozzles 20a to 20c, the matte black ink and the photo black are used. Ink other than ink is wasted.

  (10) The first on-off valve 47 and the second on-off valve are arranged so as to be aligned in the left-right direction, which is the horizontal direction, and are configured to be opened and closed in the left-right direction. For this reason, even if both the first on-off valve 47 and the second on-off valve are instantaneously opened at the time of ink switching of the switching device 25, a water head difference occurs between the mat black ink and the photo black ink. Therefore, the mixing of the two inks can be suppressed. Incidentally, when the first on-off valve 47 and the second on-off valve are arranged so as to be aligned in the vertical direction, which is the vertical direction, and are configured to be opened and closed in the vertical direction, mat black ink and photo black are used. A water head difference occurs between the inks. Therefore, when both the first on-off valve 47 and the second on-off valve are instantaneously opened at the time of ink switching, the upper ink flows into the lower ink side by its own weight, and both Ink mixes.

(Example of change)
In addition, you may change the said embodiment as follows.
As shown in FIG. 12 (a), the first communication groove 37 and the second communication groove 38 as the bubble guide channel portion extend in the horizontal direction on the upstream side and the downstream side, and a part of the middle is on the upper side. It is good also as a structure curved so that it may swell. In this case, the highest part in the curved part is the bubble retention part 62.

  As shown in FIG. 12 (b), the first communication groove 37 and the second communication groove 38 as the bubble guiding flow path portion extend in the horizontal direction on the upstream side and the downstream side, and a part of the middle is on the lower side. You may bend and comprise so that the U-shape opened to the side may be made. In this case, the highest part in the bent part is the bubble retention part 62.

  As shown in FIG. 12C, the first communication groove 37 and the second communication groove 38 as the bubble guide channel portion extend in the horizontal direction on the upstream side and the downstream side, and a part of the middle is on the lower side. You may bend and comprise so that the reverse V shape opened to the side may be made. In this case, the highest part in the bent part is the bubble retention part 62.

  As shown in FIG. 12 (d), the first communication groove 37 and the second communication groove 38 as the bubble guide channel portion extend in the horizontal direction on the upstream side and the downstream side, and a part of the middle is 2 You may curve and comprise so that it may swell to the upper part in a location. In this case, the highest part in the curved part is the bubble retention part 62. That is, the bubble retention part 62 is formed in two places. Further, in this case, a part of the first communication groove 37 and the second communication groove 38 may be curved so that the upper side swells at three or more locations.

  As shown in FIG. 12 (e), the first communication groove 37 and the second communication groove 38 as the bubble guide channel section extend in the horizontal direction on the upstream side and the downstream side, and a part of the middle is vertical. After bending downward, it may be configured to bend further in the horizontal direction. In this case, the higher part of the two bent parts becomes the bubble retention part 62.

The first communication groove 37 and the second communication groove 38 as the bubble guide channel portion may be configured by appropriately combining the modification examples shown in FIGS. 12 (a) to 12 (e).
-You may change the 1st communication groove | channel 37 and the 2nd communication groove | channel 38 as a bubble induction | guidance | derivation flow path part into the flow path comprised with pipe | tubes, such as a tube. For example, when this flow path is constituted by a tube, the tube may be routed in a loop as shown in FIG. In this case, the highest portion in the loop portion of the tube is the bubble retention portion 62.

  In the present embodiment, the switching device 25 switches the ink between the matte black ink and the photo black ink, but the ink is switched between the dark ink and the light color ink in the same color ink. You may make it perform. For example, the ink may be switched between cyan ink and light cyan ink, or between magenta ink and light magenta ink.

  The switching device 25 may be configured such that the first connection path 44 and the second connection path 45 are connected so as to form a V shape or a U shape. That is, the switching device 25 may be configured so that the connecting path 36 has a V shape or a U shape. In this case, the shape of the transmission member 46 needs to be changed as appropriate in accordance with the shape of the connecting path 36.

  In the above embodiment, an ink jet printer (printing apparatus including a fax machine, a copier, etc.) that ejects ink has been described as the liquid ejecting apparatus. However, a liquid ejecting apparatus that ejects another liquid may be used. For example, as a liquid ejecting apparatus for ejecting liquids such as electrode materials and color materials used in the manufacture of liquid crystal displays, EL displays, and surface-emitting displays, as a liquid ejecting apparatus for ejecting bioorganic materials used in biochip manufacturing, and as precision pipettes The sample injection device may be used.

  DESCRIPTION OF SYMBOLS 11 ... Inkjet printer as a liquid ejecting device, 18 ... Recording head as a liquid ejecting head, 25 ... Switching device, 33 ... First valve body housing portion constituting the first supply passage, 34 ... Constructing the second supply passage Second valve body housing portion 37, first communication groove as a bubble induction flow path portion constituting the first supply path, 38 ... second communication groove as a bubble induction flow path portion constituting the second supply path, 39... First through hole constituting the head side supply path, 40... Concave groove constituting the head side supply path, 41... Second through hole constituting the head side supply path, 44. DESCRIPTION OF SYMBOLS 1 connection path, 45 ... 2nd connection path which comprises a 2nd supply path, 47 ... 1st on-off valve, 48 ... 2nd on-off valve, 61 ... Curve part, 62 ... Bubble retention part, G ... Confluence, P ... Recording paper as a target.

Claims (7)

A liquid ejecting head that ejects liquid onto a target, and a switching device that selectively switches a type of liquid supplied to the liquid ejecting head between a first liquid and a second liquid different from the first liquid. A liquid ejecting apparatus comprising:
In the switching device,
A first supply path for supplying the first liquid;
A second supply path for supplying the second liquid;
A head side supply path that communicates between a confluence of downstream ends of the first supply path and the second supply path and the liquid ejecting head;
A first on-off valve that opens and closes the first supply path on the upstream side of the junction with the second supply path in the first supply path;
A second on-off valve that opens and closes the second supply path on the upstream side of the junction with the first supply path in the second supply path;
A liquid characterized in that bubble retention portions that permit retention of bubbles contained in the first liquid and the second liquid are respectively provided at intermediate positions of the first supply path and the second supply path. Injection device.   A bubble guide channel portion having a channel shape extending with a height difference is provided at a midpoint between the first supply channel and the second supply channel, and the bubble guide channel unit is located at a high position in the bubble guide channel unit. The liquid ejecting apparatus according to claim 1, wherein a bubble retaining portion is provided.   3. The liquid ejecting apparatus according to claim 2, wherein, in the bubble guide channel portion, a downstream nearest portion of the bubble retention portion extends in a direction lower than the bubble retention portion.   When the first liquid and the second liquid in the bubble induction channel portion are not flowing, the bubble induction channel portion causes the bubbles existing in the bubble induction channel portion to 4. The liquid ejecting apparatus according to claim 2, wherein a portion connected to the bubble retention portion extends obliquely or curved so as to be movable toward the bubble retention portion.   In the case where the first liquid or the second liquid in the bubble induction flow path portion flows along with the ejection of the first liquid or the second liquid from the liquid jet head, The downstream length of the bubble retention portion is set to such an extent that the bubbles existing in the bubble induction channel portion remain in the bubble induction channel portion by their buoyancy. Item 4. The liquid ejecting apparatus according to Item 2 or 3.   The bubble guide channel portion is present in the bubble guide channel portion when the first liquid or the second liquid in the bubble guide channel portion flows in accordance with suction from the liquid ejecting head. The length downstream of the bubble retention portion is set to such an extent that the bubbles flow downstream from the bubble guide channel portion against the buoyancy of the bubbles and are discharged from the liquid ejecting head. The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.   The liquid ejecting apparatus according to any one of claims 2 to 6, wherein the bubble guide channel portion is formed along a vertical plane.

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