JP5790453B2 - Liquid ejection device - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid from a nozzle.

  Patent Document 1 describes a recording head that discharges ink from nozzles communicating with a pressure chamber by applying pressure to each of a plurality of pressure chambers connected to a common liquid chamber (manifold). Further, in this recording head, a plurality of communication holes for connecting to a plurality of pressure chambers are formed on one wall surface of the common liquid chamber, and the plurality of communication holes serve as the length of the common liquid chamber. It is arranged along the vertical direction. Furthermore, a groove extending across the plurality of communication holes along the length direction of the common liquid chamber is formed on the wall surface of the common liquid chamber. Since such a groove is formed, ink is supplied from the groove to the communication hole even when the air bubbles in the manifold are accumulated on the communication hole, thereby causing insufficient supply of ink. Can be prevented.

Japanese Patent Laid-Open No. 2006-130813

  However, in the recording head described in Patent Document 1, there is a possibility that the ink accumulated on the communication hole flows into the pressure chamber side (inside the individual liquid channel) from the communication hole. On the other hand, when bubbles flow into the pressure chamber from the communication hole, for example, the nozzle is covered with a cap and the pump connected to the cap is driven to suck the bubble from the nozzle together with ink. Therefore, it is necessary to discharge the air bubbles that flowed in. However, when discharging bubbles, the larger the bubble that flows in, the greater the amount of ink discharged with the bubbles. Specifically, as described above, when the bubbles are sucked from the nozzle together with the ink, the suction pressure of the pump is increased or the suction time of the ink is increased as the bubbles flowing into the communication hole are larger. As a result, the amount of ink discharged along with the bubbles increases.

  An object of the present invention is to provide a liquid ejection device in which a large volume of bubbles is unlikely to enter an individual liquid channel.

  A liquid ejection apparatus according to a first invention includes a cavity unit having a plurality of individual liquid channels each having a nozzle and a common liquid chamber provided in common to the plurality of individual liquid channels, The connection ports of the plurality of individual liquid channels with the common liquid chamber are arranged along a predetermined direction, and the common liquid chamber extends along the predetermined direction, and Liquid is supplied from one end in a predetermined direction, the connection ports of the plurality of individual liquid channels and the common liquid chamber are separated by a common partition, and the partition has a thickness direction. In the portion that passes through the partition wall and extends along the predetermined direction across the connection ports of the plurality of individual liquid flow paths, and overlaps the connection port as viewed from the thickness direction, Common with connection port A groove is formed to connect the chamber, and the groove is narrower in width than the other part in a portion overlapping the connection port when viewed from the thickness direction, and the wall of the part is connected to the connection port It is characterized by blocking a part of

  According to the present invention, when liquid is supplied from one end in a predetermined direction to a common liquid chamber extending in a predetermined direction, the liquid is directed to the opposite end from the one end to the common liquid chamber. And a liquid flow in this direction also occurs in the ink in the groove extending in a predetermined direction. On the other hand, bubbles that have flowed to the vicinity of the connection port of the common liquid chamber enter the groove. Therefore, the air bubbles that have flowed to the vicinity of the connection port of the common liquid chamber and entered the groove flow along the groove from the one end portion side to the opposite end portion along the groove. This makes it difficult for bubbles to accumulate near the connection port of the common liquid chamber.

  Further, according to the present invention, the groove is narrower than the other portion in the portion overlapping the connection port, and the wall of the portion blocks a part of the connection port. The volume of is small. Therefore, even if bubbles flow into the individual liquid channel from the connection port, the bubbles have a small volume and can be easily discharged.

The liquid ejection device according to a second aspect is the liquid ejection device according to the first aspect, wherein the plurality of individual liquid flow paths are respectively a pressure chamber communicating with the nozzle, the pressure chamber, and the connection port. And a throttle channel having a partially reduced channel cross-sectional area, and further comprising an actuator for applying pressure to the liquid in the pressure chamber , The channel cross-sectional area of the portion not blocked by the groove wall is larger than the channel cross-sectional area of the throttle channel.

  When a part of the connection port is blocked by the wall of the portion where the width of the groove is narrowed, the flow path cross-sectional area of the connection port is reduced. On the other hand, when the liquid is discharged from the nozzle by applying pressure to the liquid in the pressure chamber by the actuator, the discharge characteristic of the liquid from the nozzle is the flow path among the liquid flow paths from the outlet of the common liquid chamber to the nozzle. It depends most greatly on the cross-sectional area of the channel where the cross-sectional area is the smallest. Therefore, according to the present invention, even if the flow path cross-sectional area of the connection port is small, if the flow cross-sectional area is larger than the flow path cross-sectional area of the throttle flow path, the fluctuation given to the liquid discharge characteristics from the nozzle is reduced. be able to. The channel cross-sectional area is a cross-sectional area of a cross section orthogonal to the direction of the liquid flow flowing from the common liquid chamber toward the nozzle.

A liquid ejection apparatus according to a third aspect is the liquid ejection apparatus according to the first or second aspect, wherein the groove has a width that is larger than a length of the connection port in the width direction when viewed from the thickness direction. It has a short region, and this region is included in a portion overlapping with the connection port.

  A liquid ejection device according to a fourth invention is the liquid ejection device according to any one of the first to third inventions, wherein the groove is related to the width direction in a portion overlapping the connection port as seen from the thickness direction. The narrowed shape from both sides makes the width narrower than other parts, and the walls on both sides in the width direction overlap the connecting port, thereby blocking a part of the connecting port. It is characterized by being.

  According to the present invention, the portion of the groove that overlaps the individual liquid flow path has a shape narrowed from both sides with respect to the width direction, and thus the width is narrower than the other parts. Air bubbles easily flow through the narrowed part. As a result, bubbles are less likely to accumulate in the narrowed portion of the connection channel.

In the liquid ejection apparatus according to a fifth aspect of the invention, the nozzles of the plurality of individual liquid flow paths form two nozzle rows arranged along the predetermined one direction, and the connection port is The two nozzle rows are arranged in two rows along the predetermined direction, and the grooves correspond to the connection ports arranged in two rows. Two rows are provided along the direction.

  The liquid ejection device according to a sixth aspect of the invention is the liquid ejection device according to the first aspect of the invention, wherein the groove overlaps a plurality of connection ports, and is divided into two regions separated from each other in the predetermined direction. By being divided, the plurality of connection ports are connected to the two regions, respectively.

  According to the present invention, since the connection port is connected to the two regions of the groove that are divided from each other, even if bubbles accumulate in the connection portion between the connection port and one region, the connection port and the other region The liquid is supplied to the individual liquid channel from the connecting portion. In this case, the portion of the connection channel that overlaps the individual liquid channel has a width of 0 due to the provision of the partition wall of the connection channel, and is narrower than the other portions.

  According to the present invention, when a liquid is supplied from one end in one predetermined direction to a common liquid chamber extending in one predetermined direction, the common liquid chamber is directed from the one end to the opposite end. A liquid flow occurs, and a liquid flow in this direction also occurs in the ink in the groove extending in a predetermined direction. On the other hand, bubbles that have flowed to the vicinity of the connection port of the common liquid chamber enter the groove. Therefore, the air bubbles that have flowed to the vicinity of the connection port of the common liquid chamber and entered the groove flow along the groove from the one end portion side to the opposite end portion along the groove. This makes it difficult for bubbles to accumulate near the connection port of the common liquid chamber.

  Further, according to the present invention, the groove is narrower in width than the other part in the part overlapping the connection port, and the wall of the part blocks a part of the connection port, so that bubbles accumulate in the connection port. Even so, the volume of the bubbles is small. Therefore, even if bubbles flow into the individual liquid channel from the connection port, the bubbles have a small volume and can be easily discharged.

1 is a schematic configuration diagram of a printer according to a first embodiment of the present invention. It is a top view of the inkjet head of FIG. (A) is the IIIA-IIIA sectional view taken on the line of FIG. 2, (b) is the IIIB-IIIB sectional view taken on the line of FIG. FIG. 3 is a diagram illustrating a state where a piezoelectric actuator, a cavity plate, and an aperture plate are removed from FIG. 2. FIG. 5 is an enlarged view of the vicinity of a part of the groove in FIG. 4, where (a) shows no displacement between the plates, (b) shows that the plates are displaced in one direction in the scanning direction, and (c) shows that the plates scan each other. The case where it shifted | deviated to the direction opposite to direction (b) is shown. It is a schematic block diagram of the printer which concerns on 2nd Embodiment of this invention. FIG. 6 is a view corresponding to FIG. 4 of Modification 1;

[First Embodiment]
Hereinafter, a preferred first embodiment of the present invention will be described.

  As shown in FIG. 1, the printer 1 according to the first embodiment includes a carriage 2, an inkjet head 3 (liquid ejection device), a paper transport roller 4, a suction cap 5, a suction pump 6, and the like. The carriage 2 reciprocates in the scanning direction (left and right direction in FIG. 1) along the guide bar 7. The inkjet head 3 is mounted on the carriage 2 and ejects ink from a plurality of nozzles 15 (see FIG. 2) formed on the lower surface thereof. The paper transport roller 4 transports the recording paper P in a paper feed direction (front direction in FIG. 1) orthogonal to the scanning direction.

  In the printer 1, printing is performed on the recording paper P by ejecting ink from the inkjet head 3 that moves in the scanning direction together with the carriage 2 onto the recording paper P that is transported in the paper feeding direction by the paper transporting roller 4. .

  The suction cap 5 is disposed at a position facing the lower surface of the inkjet head 3 where the nozzles 15 are opened in a state where the carriage 2 has moved to the position on the left side of FIG. It can be raised and lowered by a lifting mechanism that does not. When the suction cap 5 is raised in a state where the suction cap 5 and the inkjet head 3 face each other, the lower surface of the inkjet head 3 having a plurality of nozzles 15 opened is covered with the suction cap 5. The suction pump 6 is connected to the suction cap 5 through a tube 8.

  In the printer 1, by driving the suction pump 6 with the plurality of nozzles 15 covered with the suction cap 5, the ink in the inkjet head 3 is transferred from the nozzles 15 and dummy nozzles 16 described later to the ink in the ink. A so-called suction purge can be performed which is discharged together with bubbles or foreign matter. The ink discharged by the suction purge is stored in a waste liquid tank (not shown).

  Next, the inkjet head 3 will be described. As shown in FIGS. 2 to 4, the inkjet head 3 includes a flow path unit 21 (cavity unit) in which an ink flow path such as a nozzle 15, a pressure chamber 10, a manifold flow path 11, which will be described later, and the pressure chamber 10. And a piezoelectric actuator 22 for applying pressure to the ink inside.

  The flow path unit 21 is formed by laminating five plates of a cavity plate 31, an aperture plate 32, a base plate 33, a manifold plate 34, and a nozzle plate 35 in this order from the top. Here, among these plates 31 to 35, the plates 31 to 34 except the nozzle plate 35 are made of a metal material such as stainless steel, and the nozzle plate 35 is made of a synthetic resin material such as polyimide. Or the nozzle plate 35 may be comprised with the metal material similarly to the other plates 31-34.

  A plurality of nozzles 15 are formed on the nozzle plate 35. The plurality of nozzles 15 are arranged along the paper feed direction (predetermined one direction) to form a nozzle row 9, and the nozzle rows 9 are arranged in two rows in the scanning direction. ing. In the nozzle plate 35, the dummy nozzles 16 are formed in the upper part of the nozzle 15 constituting each nozzle row 9 in the drawing with respect to the nozzle 15 arranged on the uppermost side in FIG. 2.

  A plurality of pressure chambers 10 are formed in the cavity plate 31 corresponding to the plurality of nozzles 15 and the dummy nozzles 16. The plurality of pressure chambers 10 have a substantially elliptical planar shape whose longitudinal direction is the scanning direction, and one end in the longitudinal direction overlaps the corresponding nozzle 15 or dummy nozzle 16 in plan view. Is arranged.

  A plurality of throttle channels 12 are formed in the aperture plate 32. The plurality of throttle channels 12 are formed in substantially the lower half of the aperture plate 32, and the nozzles in the scanning direction are formed from portions overlapping the nozzles 15 in the longitudinal direction of the pressure chambers 10 and the ends opposite to the dummy nozzles 16. 15 and the dummy nozzle 16 are extended to the opposite side (in the scanning direction). Further, the throttle channel 12 passes through the aperture plate 32 at a portion overlapping the pressure chamber 10, and communicates with the pressure chamber 10.

  In addition, the aperture plate 32 has a width (length in the paper feeding direction) larger than that of the throttle channel 12 at a portion connected to the end of the plurality of throttle channels 12 on the side opposite to the pressure chamber 10. A plurality of connection ports 14 opened downward are formed, and the plurality of connection ports 14 are arranged along the paper feeding direction. In the aperture plate 32, a plurality of through holes 13a are formed in portions overlapping the nozzles 15 and the dummy nozzles 16.

  A manifold channel 11 (common liquid chamber) is formed in the manifold plate 34. The manifold channel 11 extends in the paper feed direction across a region overlapping the plurality of throttle channels 12 and the plurality of connection ports 14 in plan view. Ink is supplied to the manifold channel 11 from an ink supply port 20 provided at one end (the lower end in FIG. 2) in the paper feeding direction. In the manifold plate 34, a plurality of through holes 13c are formed in portions overlapping the plurality of through holes 13a.

  The base plate 33 is disposed between the aperture plate 32 and the manifold plate 34, thereby forming a common partition that separates the plurality of throttle channels 12 and the plurality of connection ports 14 from the manifold channel 11. . Further, two grooves 19 are formed in the base plate 33. The two grooves 19 are provided corresponding to the two nozzle rows 9, penetrate the base plate 33 in the thickness direction, and feed the paper across the plurality of connection ports 14 corresponding to the nozzle rows 9. It extends along the direction. Thereby, the connection port 14 and the manifold flow path 11 are connected via the part which overlaps with the connection port 14 in planar view of the groove | channel 19. As shown in FIG.

  Furthermore, the groove 19 has a narrower shape than the other part because it has a constricted shape from both sides in the width direction (scanning direction) in the part overlapping the connection port 14 corresponding to the nozzle 15. The portion of the base plate 33 that forms the wall of the portion where the width of the groove 19 is reduced extends to the portion that overlaps the connection port 14 in plan view. As a result, a part of the connection port 14 is blocked by the wall of the groove 19. At this time, the flow path cross-sectional area of the connection port 14 (part of the area where the connection port 14 and the groove 19 overlap (the hatched region in FIG. 4)) that is partially blocked by the wall of the groove 19 is restricted. It is larger than the cross-sectional area of the flow path 12 (the cross-sectional area of the cross section viewed from the scanning direction). The flow path cross-sectional area is a cross-sectional area of a cross section orthogonal to the direction of the ink flow flowing from the connection port 14 toward the nozzle 15.

  The base plate 33 has a plurality of through-holes 13b that overlap the plurality of through-holes 13a and 13c. And the descender flow path 13 extended in the up-down direction is formed of the three through-holes 13a-13c mutually formed in the plates 32-34.

  In the flow path unit 21, the manifold flow path 11 communicates with the pressure chamber 10 via the throttle flow path 12, and the pressure chamber 10 is connected to the nozzle 15 or the dummy nozzle via the descender flow path 13. 16 is connected. That is, the flow path unit 21 includes a plurality of individual ink flow paths 17 extending from the connection port 14 connected to the manifold flow path 11 to the nozzle 15 via the throttle flow path 12, the pressure chamber 10, and the descender flow path 13. Two dummy ink channels 18 extending from the connection port 14 connected to the manifold channel 11 to the dummy nozzle 16 through the throttle channel 12, the pressure chamber 10 and the descender channel 13 are formed. The manifold channel 11 is provided in common to the plurality of individual ink channels 17 and the dummy ink channel 18, and the connection port 14 of the dummy ink channel 18 is connected to the manifold channel 11. 11 is connected to a portion opposite to the ink supply port 20 (one end portion of the manifold channel) across the connection port 14 of the individual ink channel 17.

  In addition, each individual ink channel 17 and dummy ink channel 18 have a partially reduced channel cross-sectional area in the throttle channel 12, and the throttle channel 12 is the smallest part of the channel cross-sectional area. It has become. Further, the dummy ink flow path 18 has individual diameters such that the diameter of the dummy nozzle 16 is larger than the diameter of the nozzle 15, the height of the throttle flow path 12 is higher than the individual ink flow path 17, and the like. The channel resistance is smaller than that of the ink channel 17.

  The piezoelectric actuator 22 includes a vibration plate 41, a piezoelectric layer 42, a common electrode 43, a plurality of individual electrodes 44, and the like. The diaphragm 41 is made of a piezoelectric material mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and is bonded to the upper surface of the cavity plate 31 so as to cover the plurality of pressure chambers 10. Has been. Note that the diaphragm 41 may be made of a material other than the piezoelectric material, unlike the piezoelectric layer 42 described below.

  The piezoelectric layer 42 is made of the same piezoelectric material as that of the vibration plate 41, and is continuously formed on the upper surface of the vibration plate 41 across the plurality of pressure chambers 10. The common electrode 43 is continuously formed across the entire region between the diaphragm 41 and the piezoelectric layer 42. The common electrode 43 is connected to a driver IC (not shown) and is always held at the ground potential.

  The plurality of individual electrodes 44 have a substantially oval planar shape that is slightly smaller than the pressure chamber 10, and face the substantially central portion of the pressure chamber 10 of the plurality of individual ink flow paths 17 on the upper surface of the piezoelectric layer 42. Are arranged to be. Further, the end of the individual electrode 44 opposite to the nozzle 15 in the longitudinal direction extends to a portion that does not face the pressure chamber 10, and the tip thereof is a connection terminal 44 a for connecting to a wiring member (not shown). It has become. Each of the plurality of individual electrodes 44 is connected to a driver IC (not shown) via a wiring member (not shown), and either of the ground potential and a predetermined drive potential (for example, about 20 V) is selected by the driver IC. A potential is selectively applied. Further, the portion of the piezoelectric layer 42 sandwiched between the common electrode 43 and the individual electrode 44 is polarized in the thickness direction.

  Here, a method of discharging the ink from the nozzle 15 by driving the piezoelectric actuator 22 will be described. In the inkjet head 3, all the individual electrodes 44 are held at the ground potential in advance. Then, when the potential of an individual electrode 44 is switched from the ground potential to the driving potential, a potential difference is generated between the individual electrode 44 and the common electrode 43, and due to this potential difference, the individual electrode 44 and the common electrode of the piezoelectric layer 42 are generated. An electric field in the thickness direction is generated at a portion sandwiched by 43. Since the direction of the electric field is parallel to the direction of polarization of the piezoelectric layer 42, this portion of the piezoelectric layer 42 contracts in the horizontal direction orthogonal to the polarization direction, thereby causing the pressure of the diaphragm 41 and the piezoelectric layer 42 to be reduced. The portion facing the chamber 10 is deformed so as to be convex toward the pressure chamber 10 as a whole. As a result, the volume of the pressure chamber 10 is reduced, the ink pressure in the pressure chamber 10 is increased, and ink is ejected from the nozzle 15 communicating with the pressure chamber 10.

  In addition, since the individual electrode 44 is not provided for the pressure chamber 10 in the dummy ink flow path 18, ink is not ejected from the dummy nozzle 16.

  Here, bubbles or the like may be mixed in the ink supplied from the ink supply port 20 to the manifold channel 11, and bubbles may exist in the manifold channel 11. When the bubbles flow into the individual ink flow path 17, the ink ejection characteristics from the nozzle 15 when the piezoelectric actuator 22 is driven fluctuate. For this reason, when bubbles flow into the individual ink channel 17, they are discharged together with the bubble ink in the individual ink channel 17 by the above-described suction purge.

  However, when the bubbles flowing into the individual ink flow path 17 are large, it is necessary to increase the suction pressure of the suction pump 6 or lengthen the suction time by the suction pump 6 in order to discharge the bubbles by suction purge. As a result, the amount of ink discharged from the inkjet head 3 together with the bubbles increases.

  In contrast, in the first embodiment, the base plate 33 serving as a partition wall between the manifold channel 11 and the plurality of connection ports 14 extends continuously along the paper feeding direction across the plurality of connection ports 14. A groove 19 is formed. On the other hand, since ink is supplied to the manifold channel 11 from an ink supply port 20 provided at one end (the lower end in FIG. 2) in the paper feeding direction, the manifold channel 11 is indicated by an arrow R. Thus, an upward ink flow in FIG. 2 is generated from one end connected to the ink supply port 20 toward the other end. The ink flow in the direction indicated by the arrow R also occurs in the groove 19 due to the ink flow in the manifold channel 11.

  Therefore, the bubbles flowing near the connection port 14 of the manifold channel 11 flow into the groove 19 and flow in the direction of the arrow R along the groove 19 due to the ink flow in the groove 19 described above. For this reason, it is difficult for bubbles to flow from the connection port 14 into the individual ink flow path 17.

  Further, the groove 19 is narrower than the other part in the portion overlapping the connection port 14, and a part of the connection port 14 is blocked by the wall of the groove 19. Bubbles that can stay in the overlapping area have a small volume. Therefore, even if bubbles flow into the individual ink flow path 17 from the connection port 14, the flowed bubbles have a small volume, and the bubbles can be easily discharged by suction purge. Specifically, in the suction purge, the air bubbles flowing into the individual ink flow path 17 are discharged without increasing the suction pressure of the suction pump 6 or increasing the time for sucking the ink by the suction pump 6. Can do. As a result, ink consumption due to suction purge can be reduced.

  Here, considering only the purpose of reducing the volume of bubbles flowing into the individual ink flow path 17, it is considered that the groove 19 has a constant width comparable to the portion overlapping the connection port 14. It is done. However, in the first embodiment, this is not done, and the width of the groove 19 is narrowed only in the portion overlapping the connection port 14. This is because a sufficient ink flow is generated in the groove 19 by increasing the width of the groove 19 in a portion that does not overlap the connection port 14.

  In the first embodiment, a part of the connection port 14 is blocked by the wall of the groove 19, thereby reducing the cross-sectional area of the connection port 14. It is larger than the channel cross-sectional area of the throttle channel 12. For this reason, the ejection characteristics of the ink from the nozzles 15 are most dependent on the channel cross-sectional area of the throttle channel 12, which is the portion of the individual ink channel 17 having the smallest channel cross-sectional area. Therefore, when the connection port 14 is not blocked by the wall of the groove 19 even if the flow passage cross-sectional area of the connection port 14 is small because a part of the connection port 14 is blocked by the wall of the groove 19. On the other hand, the ink ejection characteristics from the nozzles 15 do not vary greatly.

  In addition, since the groove 19 has a shape narrowed from both sides in the width direction (scanning direction) in the portion overlapping the connection port 14, the width of the groove 19 is narrower than the other portions. Compared with the case where the portion overlapping with the connection port 14 is constricted from only one side in the width direction, bubbles easily flow through the portion where the width of the groove 19 is narrow. Therefore, bubbles are less likely to accumulate in the portion of the groove 19 that overlaps the connection port 14, and bubbles are less likely to flow into the individual ink flow path 17 from the connection port 14.

  In the first embodiment, a plurality of plates including the aperture plate 32 in which the connection port 14 is formed and the base plate 33 in which the partition wall between the connection port 14 and the manifold channel 11 is formed in which the groove 19 is formed. The manifold channels 11 and the plurality of individual ink channels 17 are formed by stacking 31 to 35. For this reason, when the plates 31 to 35 are joined, the aperture plate 32 and the base plate 33 may be joined in a slightly shifted state.

  However, in the first embodiment, the portion of the groove 19 that overlaps the connection port 14 is constricted from both sides in the width direction, so that the walls on both sides in the width direction of the groove 19 are respectively connected to the connection port 14. Therefore, even when the aperture plate 32 and the base plate 33 are joined in a state shifted in the scanning direction, the channel cross-sectional area of the connection port 14 partially blocked by the wall of the groove 19. Does not fluctuate so much.

  More specifically, when the aperture plate 32 and the base plate 33 are joined without positional displacement, the connection port 14 and the groove 19 have a positional relationship as shown in FIG. 5A, for example. On the other hand, when the aperture plate 32 is joined to the base plate 33 in a state shifted to the right side in FIG. 2, the right wall in the drawing of the groove 19 is connected as shown in FIG. While the area | region which plugs the opening | mouth 14 increases, the area | region where the left wall in the figure block | closes the connection opening | mouth 14 reduces. On the other hand, when the aperture plate 32 is joined to the base plate 33 in a state of being shifted to the left side in FIG. 2, the right side of the groove 19 in the drawing is shown in FIG. The area where the wall closes the connection port 14 decreases, and the area where the wall on the left side closes the connection port 14 increases. Therefore, even if the aperture plate 32 and the base plate 33 are joined in a state shifted in the scanning direction, the flow path cross-sectional area of the connection port 14 does not vary so much.

  In some cases, the aperture plate 32 and the base plate 33 are joined in a state shifted in the paper feeding direction. In this case, the flow path cross-sectional area of the connection port 14 partially blocked by the wall of the groove 19. Fluctuates. However, in this case, since the flow path cross-sectional areas of all the connection ports 14 fluctuate to the same extent, there is no variation in the ink ejection characteristics between the nozzles 15.

  In the first embodiment, the dummy ink flow path 18 is connected to the downstream side of the connection port 14 corresponding to the nozzle 15 with respect to the ink flow direction (direction indicated by the arrow R) in the manifold flow path 11. Since the opening 14 is provided, the bubbles flowing along the groove 19 tend to finally flow into the dummy ink flow path 18.

  Here, as described above, since the dummy ink flow path 18 has a smaller flow resistance than the individual ink flow path 17, the bubbles flowing into the dummy ink flow path 18 are efficiently discharged by suction purge. be able to.

[Second Embodiment]
Next, a preferred second embodiment of the present invention will be described. However, in the second embodiment, only a part of the configuration is different from that of the first embodiment, and therefore only the parts different from the first embodiment will be described below.

  In the second embodiment, as shown in FIG. 6, a groove 51 is formed in the base plate 33 instead of the groove 19 (see FIG. 4). Like the groove 19, the groove 51 penetrates the base plate 33 in the thickness direction and extends along the paper feed direction so as to straddle the plurality of connection ports 14 corresponding to the nozzle rows 9. Unlike the groove 19, the region overlapping the connection port 14 is divided into two regions 52. As a result, the connection port 14 is connected to each of the two regions 52, and a part thereof is blocked by the wall 53 that separates the two regions 52. In other words, the groove 51 has a width of 0 in the portion that becomes the wall 53 between the two regions 52. Also in the second embodiment, the area of the flow path cross-sectional area of the connection port 14 partially blocked by the wall 53 (the region where the connection port 14 and the region 52 overlap (the hatched region in FIG. 7)). ) Is larger than the channel cross-sectional area of the throttle channel 12.

  Also in this case, since a part of the connection port 14 is blocked by the wall 53 that separates the region 52 of the groove 51, the cross-sectional area of the flow path of the connection port 14 is reduced, and bubbles are generated in the individual ink flow channel 17. Even if it flows in, the volume becomes small and it can be easily discharged by suction purge.

  Furthermore, in the second embodiment, since the connection port 14 is connected to the two regions 52 of the groove 51 that are divided from each other, even when bubbles accumulate in the connection portion between the connection port 14 and the one region 52. Ink is supplied to the individual ink flow path 17 from the connection portion between the connection port 14 and the other region 52. Therefore, it is possible to prevent insufficient supply of ink to the individual ink flow path 17.

  Next, modified examples in which various changes are made to the first and second embodiments will be described. However, the description of the same configuration as that of the first and second embodiments will be omitted as appropriate.

  In the first embodiment, the portion of the groove 19 that overlaps the connection port 14 has a shape narrowed from both sides in the width direction, so that the width is narrower than other portions, and the width of the groove 19 Although the walls on both sides with respect to the direction closed a part of the connection port 14, this is not restrictive. In one modified example (modified example 1), as shown in FIG. 7, the portion of the groove 19 that overlaps the connection port 14 has a constricted shape from only one side in the width direction (inside in the scanning direction). The width is narrower than the other portions, and only the wall on one side of the groove 19 blocks a part of the connection port 14.

  Even in this case, the groove 19 is narrower in the portion overlapping the connection port 14 than the other portion, and a part of the connection port 14 is blocked by the wall of the groove 19. As in the above embodiment, even if bubbles flow into the individual ink flow path 17 from the connection port 14, the bubbles that flow in have a small volume and can be easily discharged by suction purge.

  However, in this case, compared with the case where the portion overlapping the connection port 14 of the groove 19 is constricted from both sides in the width direction, the bubbles are less likely to flow through the portion where the width of the groove 19 is narrow, Air bubbles tend to accumulate in the portion of the groove 19 that overlaps the connection port 14. Therefore, as compared with the first embodiment, bubbles easily flow from the connection port 14 into the individual ink flow path 17.

  Further, in this case, when the aperture plate 32 and the base plate 33 are joined in a state shifted in the scanning direction, the flow path of the connection port 14 corresponding to one of the two nozzle rows 9 is cut off. While the area increases, the flow path cross-sectional area of the connection port 14 corresponding to the other nozzle row 9 decreases. For this reason, when the deviation in the scanning direction between the aperture plate 32 and the base plate 33 is large, there is a possibility that the ejection characteristics of ink from the nozzles 15 vary between the nozzle rows 9.

  In Modification 1, the portion overlapping the connection port 14 of the groove 19 was constricted only from the inner side in the scanning direction. Conversely, the portion overlapping the connection port 14 of the groove 19 was The shape may be constricted only from the outside in the scanning direction.

  In the first and second embodiments, a dummy ink flow path 18 is provided separately from the individual ink flow path 17, and the flow resistance of the dummy ink flow path 18 is equal to the flow of the individual ink flow path 17. The resistance is smaller than the path resistance, and the individual electrode 44 is not provided for the pressure chamber 10 of the dummy ink flow path 18, but is not limited thereto.

  That is, the channel resistance of the individual ink channel 17 and the channel resistance of the dummy ink channel 18 are the same, for example, the individual ink channel 17 and the dummy ink channel 18 have the same structure. May be. Further, the dummy ink flow path 18 is not limited to having the same narrow flow path 12, pressure chamber 10, and descender flow path 13 as the individual ink flow path 17, but the manifold flow path 11, the dummy nozzle 16, and the like. It may have another structure for connecting the two.

  An individual electrode 44 may also be provided for the pressure chamber 10 in the dummy ink flow path 18. However, since ink is not ejected from the dummy nozzle 16, the individual electrode 44 corresponding to the dummy ink flow path 18 is always held at the ground potential, and the drive potential is not applied. Furthermore, the dummy ink flow path 18 may not be provided.

  In the first and second embodiments, the five plates 31 to 35 including the aperture plate 32 in which the connection port 14 is formed and the base plate 33 in which the grooves 19 and 51 are formed are stacked on each other. Thus, the flow path unit 21 having flow paths such as the manifold flow path 11 and the individual ink flow path 17 is formed. However, the present invention is not limited to this. For example, the flow path unit 21 may be formed by stacking four or less or six or more plates. Alternatively, the flow path unit 21 may have a structure other than a structure in which a plurality of plates are stacked.

  In the first and second embodiments, the channel cross-sectional area of the connection port 14 partially blocked by the wall of the groove 19 and the wall 53 is larger than the channel cross-sectional area of the throttle channel 12. However, the channel cross-sectional area of the connection port 14 may be equal to or smaller than the channel cross-sectional area of the throttle channel 12. However, in this case, since the flow passage cross-sectional area of the individual ink flow passage 17 becomes the smallest at the connection port 14, the ink from the nozzle 15 depends on how much the connection port 14 is blocked by the wall of the groove 19. The discharge characteristics vary greatly. Therefore, it is necessary to adjust the driving potential according to how much the connection port 14 is blocked by the wall of the groove 19.

  In the first embodiment, the groove 19 continuously extends across the plurality of connection ports 14 of each nozzle row 9. However, the present invention is not limited to this, and the groove 19 may be any adjacent connection port. 14 may be divided into two regions.

  In the first and second embodiments, ink is discharged from the nozzle 15 and the dummy nozzle 16 together with bubbles and foreign matter by so-called suction purge. However, the present invention is not limited to this. For example, the ink may be discharged from the nozzle 15 and the dummy nozzle 16 together with bubbles and foreign matter by so-called push purge that applies positive pressure to the ink in the ink flow path upstream of the manifold flow path 11.

  In the above description, an example in which the present invention is applied to an ink jet head that discharges ink from the nozzle 15 by applying pressure to ink in the pressure chamber 10 by the piezoelectric actuator 22 has been described. The present invention can also be applied to an inkjet head that ejects ink from nozzles by applying ejection energy to the ink. Furthermore, the present invention can also be applied to a liquid ejection apparatus other than an inkjet head that ejects a liquid other than ink from a nozzle.

DESCRIPTION OF SYMBOLS 3 Inkjet head 10 Pressure chamber 11 Manifold flow path 12 Restriction flow path 14 Connection port 15 Nozzle 16 Dummy nozzle 17 Individual ink flow path 18 Dummy ink flow path 19 Groove 21 Flow path unit 32 Aperture plate 33 Base plate 51 Groove 52 Area 53 Wall

Claims (6)

A plurality of individual liquid passages each having a nozzle, and a common liquid chamber provided in common to the plurality of individual liquid passages, and a cavity unit,
Connection ports with the common liquid chambers of the plurality of individual liquid flow paths are arranged along a predetermined direction,
The common liquid chamber extends along the predetermined direction, and liquid is supplied from one end of the predetermined direction,
The connection ports of the plurality of individual liquid channels and the common liquid chamber are separated by a common partition,
The partition wall penetrates the partition wall in the thickness direction, and extends along the predetermined direction across the connection ports of the plurality of individual liquid flow paths, as viewed from the thickness direction. In the portion that overlaps the connection port, a groove that connects the connection port and the common liquid chamber is formed,
The groove is narrower in width than the other part in a portion overlapping with the connection port when viewed from the thickness direction, and a wall of the part blocks a part of the connection port. Discharge device. Each of the plurality of individual liquid channels is
A pressure chamber communicating with the nozzle;
A throttle channel which is provided between the pressure chamber and the connection port and has a partially reduced channel cross-sectional area;
An actuator for applying pressure to the liquid in the pressure chamber;
2. The liquid according to claim 1, wherein a flow path cross-sectional area of a portion of the connection port that is not blocked by the groove wall is larger than a flow path cross-sectional area of the throttle flow path. Discharge device. The groove has a region whose width is shorter than the length of the connection port in the width direction when viewed from the thickness direction, and this region is included in a portion overlapping the connection port. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is a liquid ejection apparatus.   The groove has a shape narrowed from both sides in the width direction in a portion overlapping with the connection port when viewed from the thickness direction, and thus the width is narrower than other portions, and the groove is related to the width direction. The liquid ejection apparatus according to claim 1, wherein walls on both sides overlap with the connection port to block a part of the connection port. The nozzles of the plurality of individual liquid passages form two nozzle rows arranged along the predetermined one direction,
The connection ports are arranged in two rows along the predetermined direction corresponding to the two nozzle rows,
  5. The groove according to claim 1, wherein the groove is provided in two rows along the predetermined one direction, corresponding to the connection ports arranged in two rows. Liquid ejection device.   The groove is divided into two regions spaced apart from each other in the predetermined direction at a portion where the groove overlaps the plurality of connection ports, so that the plurality of connection ports are connected to the two regions, respectively. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus.

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