JP2006096036A - Liquid transporting apparatus and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid transporting apparatus which can surely discharge bubbles in a liquid passage by generating a swirling flow in the liquid passage by a simple constitution. <P>SOLUTION: Mainstream regions 20a-22a where a mainstream of ink flows, and branch stream regions 20b-22b which are located at the outer side than the mainstream regions 20a-22a and where a branch stream of ink flows are formed respectively in passage forming holes 20-22 which constitute a part of discrete ink passages 25 formed in a passage unit 2. The mainstream regions 20a-22a are arranged to nearly overlap with each other. The branch stream regions 20b-22b are arranged to partially overlap with adjoining other branch stream regions and also to sequentially shift in one of peripheral directions into a spiral form. The branch stream of ink becomes the swirling flow, so that the bubbles staying in the discrete ink passage 25 can be discharged surely. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid transfer apparatus for transferring a liquid and a method for manufacturing the same.

  Conventionally, there are liquid transfer devices that can transfer various liquids. Among them, there is an ink jet head that transfers ink to a nozzle and discharges ink from the nozzle to a sheet or the like. The inkjet head includes a flow path unit including a plurality of ink flow paths including pressure chambers communicating with nozzles, and an actuator unit that applies pressure to the ink in the pressure chamber. Some ink jets are configured to eject ink from nozzles communicating with the pressure chamber by selectively applying pressure to the ink.

  By the way, in such an ink jet head, if air bubbles are mixed into the ink flow path from the outside and the air bubbles remain in the ink flow path, the actuator unit converts the air into the ink in the pressure chamber (in the ink flow path). Since pressure cannot be reliably applied, a general inkjet head is configured to be able to perform a purge operation for forcibly discharging bubbles together with ink from nozzles. However, even if the above-described purging operation is performed, it is difficult to discharge bubbles adhering to the vicinity of the wall surface because the flow velocity of ink near the wall surface of the ink flow path is low. Therefore, in order to completely discharge bubbles in the ink flow path, it is necessary to repeatedly execute the purge operation many times, and the ink is often consumed wastefully. In view of this, there has been proposed an ink jet head configured to generate a vortex in the ink flow path so as to increase the flow rate of ink near the wall surface and thereby more reliably discharge bubbles.

  For example, in the ink jet head described in Patent Document 1, the ink supply path for supplying ink to the pressure chamber is disposed on the tangent to the side wall of the pressure chamber, and the vortex flows into the pressure chamber when the ink flows into the pressure chamber. Is configured to occur. In addition, in the ink jet head described in Patent Document 2, a spiral hole is formed in a filter provided in the middle of the ink flow path, and a vortex is generated in the ink flow path by the hole. It is configured.

JP-A-5-16211 JP-A-1-297252

In the ink jet head described in Patent Document 1, since eddy currents are generated in the pressure chamber, bubbles remaining in the pressure chamber are easily discharged. However, in actuality, the ink flow path formed in the flow path unit has many parts where the flow area increases or decreases, such as a bent part or a nozzle peripheral part where the flow area decreases rapidly, In particular, bubbles are likely to remain in the corners formed in such a portion. However, it is difficult to completely discharge the bubbles remaining in the middle of the ink flow path only by the vortex generated in the pressure chamber. In addition, in the ink jet head described in Patent Document 2, it is possible to discharge bubbles partially remaining around the filter by the action of vortex generated in the spiral hole formed in the filter. In order to completely discharge bubbles remaining in the ink flow path, it is necessary to provide a filter having a spiral hole in each part of the ink flow path, the flow path resistance is increased, and the manufacturing cost is also reduced. It is disadvantageous.

In order to manufacture the ink flow path of the ink jet head, it is advantageous from the viewpoint of manufacturing by laminating a plurality of plates. In such a case, the ink circulation holes reaching the nozzles are communicated by forming the ink circulation holes in each plate and laminating those plates. However, when plates are laminated in this way to form a flow path, a step (or a corner) may occur between adjacent plates, and bubbles are likely to accumulate in such a step. Even if the holes of each plate are designed to be the same so that a smooth flow path is formed, the position of the holes may vary from several micrometers to several tens of micrometers between adjacent plates when the plates are stacked. Such misalignment will cause a step between adjacent plates. Therefore, in the ink jet head (laminated head) of the type in which the flow path is formed by laminating plates, the remaining of bubbles is particularly serious.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid transfer apparatus having a laminated type flow path unit capable of generating a vortex in a liquid flow path with a simple configuration and reliably discharging bubbles in the liquid flow path. That is.

Means for Solving the Problems and Effects of the Invention

  According to a first aspect of the present invention, there is provided a liquid transfer device including a flow path unit having a liquid flow path, and a transfer force applying mechanism that applies a transfer force to the liquid in the liquid flow path, The flow path unit has a plurality of stacked plates each having a plurality of flow path forming holes forming at least a part of the liquid flow path, and each of the plurality of flow path forming holes has a plurality of flow path forming holes. A main flow region substantially overlapping with each other when viewed from a direction orthogonal to the plate, and a tributary region located outside the main flow region when viewed from a direction orthogonal to the plate are formed, A liquid transfer device is provided in which the tributary regions adjacent to each other in the stacking direction of the plates are provided so as to partially overlap each other when viewed from the orthogonal direction, and are arranged in a spiral shape.

  In this liquid transfer device, the liquid is transferred to a predetermined position along the liquid flow path of the flow path unit by the transfer force applying mechanism. The flow path unit has a plurality of stacked plates, and a plurality of flow path forming holes constituting at least a part of the liquid flow path are formed in each of the plurality of plates. In each of the plurality of flow path forming holes, a main flow region in which the main flow of the liquid flows and a tributary region located outside the main flow region are formed. In the present application, the term “mainstream region” refers to a region that substantially overlaps when viewed from a direction orthogonal to the plate in the flow path formation hole formed in each plate. It is considered that the main flow out of the liquid flow smoothly flows through the flow path defined by these main flow regions. On the other hand, the term “branch region” refers to a region other than the mainstream region in the flow path forming holes formed in each plate. In the present invention, since the plurality of tributary regions are arranged in a spiral shape while partially overlapping each other, it is considered that the tributaries of the liquid flowing through the plurality of tributary regions become vortex flows. Therefore, the flow velocity of the liquid in the vicinity of the wall surface of the liquid channel is increased, and the bubbles staying in the vicinity of the wall surface can be reliably discharged. Further, it is not necessary to perform the bubble discharging operation (purging operation) many times to discharge the bubbles, and the amount of liquid discharged during the purging operation is reduced, so that the liquid can be used more efficiently. Furthermore, it is possible to reliably generate a vortex in the liquid flow path with a simple configuration consisting of only a plurality of flow path forming holes respectively formed at predetermined positions of a plurality of plates, which is advantageous in terms of manufacturing cost. . In addition, it is not necessary that the main flow region and the tributary region exist in the flow passage formation holes of all the plates constituting the flow passage unit, and the main flow region and the flow passage formation holes of a plurality of plates among the plates constituting the flow passage unit It is sufficient that a tributary region exists. For example, even if the flow path unit is formed of a cavity plate, a base plate, a plurality of manifold plates, and a nozzle plate as in an embodiment described later, only the main flow region and the tributary region are included in the cavity plate, the base plate, and several manifold plates. May be present.

  In the liquid transfer device of the present invention, a plurality of the tributary regions can be formed in one flow path forming hole. In this case, since a plurality of vortex flows respectively flowing through the plurality of tributary regions are generated, the bubbles staying in the liquid flow path can be more reliably discharged.

  In the liquid transfer device of the present invention, the plurality of tributary regions formed in the one flow path forming hole may be arranged at equiangular intervals in the circumferential direction forming the spiral. As described above, since the plural tributary regions are arranged at equiangular intervals, the vortex generated in the plural tributary regions flows uniformly in the circumferential direction, and the bubbles staying in the liquid flow path are surely discharged. it can.

  In the liquid transfer device of the present invention, the main flow region and the tributary region may be connected in the flow path forming hole. In this case, since the main flow and the tributary of the liquid are not separated, the liquid flows more smoothly.

  In the liquid transfer device of the present invention, the flow path forming hole may be formed in an oval shape elongated in one direction. Therefore, it is possible to reliably generate a vortex flow in the liquid flow path with a simple-shaped flow path forming hole. Further, the flow path forming hole can be easily formed.

  In the liquid transfer device of the present invention, the center lines of the plurality of main flow regions may coincide. In this case, the mainstream flow becomes smoother.

  In the liquid transfer device according to the present invention, the tributary regions may be located at an equal angle to each other in the circumferential direction of drawing the spiral in adjacent plates. In this case, since the flow path resistance is made uniform with respect to the flow direction of the liquid, the main flow and the vortex tributary flow stably flow.

  In the liquid transfer device of the present invention, the liquid flow path may include a nozzle that discharges liquid to the outside of the flow path unit, and the plurality of flow path forming holes may define a liquid flow path in the vicinity of the nozzle. . In the liquid flow path in the vicinity of the nozzle, since the flow path area is suddenly reduced, bubbles are particularly likely to stay. However, by generating a vortex in such a portion, the bubbles can be reliably discharged.

  In the liquid transfer device of the present invention, the transfer force applying mechanism may be an actuator unit. In this case, a transfer force can be applied to the liquid with a simple configuration.

  According to the second aspect of the present invention, in the liquid transfer device, a plurality of plates each having through holes are formed, and the through holes are arranged on a predetermined axis so as to define a flow path. A flow path unit having a liquid discharge port that communicates with the flow path, and a transfer force applying mechanism that applies a transfer force to the liquid in the flow path. Provided is a liquid transfer device in which the walls defining the through holes of the plurality of plates are arranged so as to draw a spiral around the axis as the outermost part farthest from the axis approaches the liquid outlet. . In the liquid transfer device of the present invention, since the outermost part of the through hole is arranged so as to draw a spiral, a spiral liquid flow is generated in the flow path, and bubbles generated in the flow path unit of the laminated structure are liquidated. Can be spilled along with.

  In the liquid transfer device of the present invention, the through holes formed in the plurality of plates are each elliptical, the center of the ellipse is located on the axis, and the rotation angle of the ellipse with respect to the axis in the plurality of plates is May be different. The through holes formed in the plurality of plates may be rotationally symmetric, the center of rotational symmetry may be located on the axis, and the rotation angles of the through holes with respect to the axis may be different in the plurality of plates. The through hole may include a plurality of holes.

  In the liquid transfer device of the present invention, the through hole of each plate may have a main flow region that overlaps through the through holes of a plurality of plates and a tributary region that overlaps only between adjacent plates.

  The liquid transfer apparatus of the present invention may further include another plate having a through hole that communicates with the liquid discharge port and corresponds to only the main flow region. Furthermore, it has another plate in which nozzle holes are formed, and the nozzle holes can serve as the liquid discharge port.

  According to a third aspect of the present invention, there is provided a method for manufacturing a liquid transfer device according to the second aspect of the present invention, wherein a plurality of plates each having through holes are formed on a predetermined axis. Are arranged so that a flow path is defined and the outermost wall farthest from the axis of the wall defining the through hole is arranged in a spiral around the axis as it approaches the liquid discharge port Thus, there is provided a method of manufacturing a liquid transfer device, including forming a flow path unit and providing a transfer force applying mechanism that applies a transfer force to the liquid in the flow path. By this manufacturing method, a spiral liquid flow is generated in the flow path, so that it is difficult for bubbles to remain even if the flow path unit has a laminated structure.

In the manufacturing method of the present invention, the plurality of plates include first to third plates in which first to third through holes having the same shape are formed, and the shafts of the first to third through holes are provided. The rotation angles with respect to may be different from each other. The plurality of plates may include first to third plates formed with first to third through holes, respectively, and the shape of the first through holes may be different from the shape of the second through holes. The method for manufacturing the liquid transfer device may further include providing a pressure chamber between the flow path unit and the transfer force applying mechanism.

Embodiments of the present invention will be described. The present embodiment is an example in which the present invention is applied to an inkjet head that ejects ink onto recording paper.
First, the ink jet printer 100 including the ink jet head 1 will be briefly described. As shown in FIG. 1, an inkjet printer 100 includes a carriage 101 that can move in the left-right direction in FIG. 1, a serial inkjet head 1 that is provided on the carriage 101 and discharges ink onto a recording paper P, A conveyance roller 102 that conveys the recording paper P forward in FIG. 1 is provided. The inkjet head 1 moves in the left-right direction (scanning direction) integrally with the carriage 101, and ejects ink onto the recording paper P from the emission port of the nozzle 24 formed on the ink ejection surface 5 on the lower surface thereof. Then, the recording paper P recorded by the inkjet head 1 is discharged forward (paper feeding direction) by the transport roller 102.

  The inkjet printer 100 includes a purge cap 103 (see FIG. 8) that is detachably attached to the ink ejection surface 5 of the inkjet head 1, a purge pump (not shown) connected to the purge cap 103, and the like. It has. In this purge mechanism, the purge cap 103 is attached to the ink discharge surface 5 and the purge pump sucks out bubbles mixed in the ink flow path in the inkjet head 1 together with the ink from the nozzle 24 to the purge cap 103. Discharge air bubbles to the outside.

Next, the inkjet head 1 will be described in detail with reference to FIGS.
As shown in FIGS. 2 to 5, the inkjet head 1 includes a flow path unit 2 in which an individual ink flow path 25 including a pressure chamber 16 is formed, and an actuator stacked on the upper surface of the flow path unit 2. And a unit 3 (transfer force applying mechanism).

  First, the flow path unit 2 will be described. As shown in FIG. 4, the flow path unit 2 includes a cavity plate 10, a base plate 11, manifold plates 12, 13 and 14, and a nozzle plate 15, and these six plates 10 to 15 are stacked in this order from the top. It is adhered in the state where it was done. Among these, the cavity plate 10, the base plate 11, and the manifold plates 12 to 14 are stainless steel plates having the same thickness, and these five plates 10 to 14 include a manifold 17 and a pressure chamber 16 described later. Individual ink flow paths 25 are formed by etching. Further, the nozzle plate 15 is formed of, for example, a polymer synthetic resin material such as polyimide, and is bonded to the lower surface of the manifold plate 14. Or this nozzle plate 15 may be formed with metal materials, such as stainless steel, similarly to the five plates 10-15.

  As shown in FIGS. 2 to 5, the cavity plate 10 is formed with a plurality of pressure chambers 16 arranged along a plane. The plurality of pressure chambers 16 are open on the surface of the flow path unit 2 (the upper surface of the cavity plate 10 to which a diaphragm 30 described later is joined). Each pressure chamber 16 is formed in a substantially elliptical shape in plan view, and is arranged so that the major axis direction thereof is the left-right direction (scanning direction). The cavity plate 10 is formed with an ink supply port 18 connected to an ink tank (not shown).

  As shown in FIGS. 3 and 4, flow path forming holes 19 and 20 are formed at positions overlapping the both ends of the pressure chamber 16 in the long axis direction in plan view of the base plate 11. Further, the three manifold plates 12 to 14 are formed with a manifold 17 that extends in the paper feeding direction (vertical direction in FIG. 2) and overlaps either one of the left and right ends of the pressure chamber 16 in plan view. Ink is supplied to the manifold 17 from an ink tank through an ink supply port 18. Further, the three manifold plates 12 to 14 are formed with flow path forming holes 21, 22, and 23 at positions overlapping the flow path forming holes 19 in plan view. Furthermore, a plurality of nozzles 24 are formed in the nozzle plate 15 at positions that overlap with the ends of the plurality of pressure chambers 16 opposite to the manifolds 17 in plan view. The nozzle 24 is formed by, for example, performing excimer laser processing on a polymer synthetic resin substrate such as polyimide.

  As shown in FIG. 4, the manifold 17 communicates with the pressure chamber 16 through the flow path forming hole 19, and the pressure chamber 16 communicates with the nozzle 24 through the flow path forming holes 20 to 23. Yes. As described above, the individual ink flow path 25 extending from the manifold 17 to the nozzle 24 through the pressure chamber 16 is formed in the flow path unit 2. The flow path forming holes 20 to 23 are formed in a special shape so that bubbles in the individual ink flow path 25 are easily discharged (see FIG. 6), which will be described in detail later.

  Next, the actuator unit 3 will be described. As shown in FIGS. 2 to 5, the actuator unit 3 includes a conductive diaphragm 30 disposed on the surface of the flow path unit 2, a piezoelectric layer 31 formed on the surface of the diaphragm 30, A plurality of individual electrodes 32 formed corresponding to the plurality of pressure chambers 16 are provided on the surface of the piezoelectric layer 31. The actuator unit 3 applies ink to the ink in the pressure chamber 16 as a force to be transferred to the nozzle 24, thereby transferring the ink along the individual ink flow path 25 and discharging it from the nozzle 24. It is.

  The diaphragm 30 is a substantially rectangular stainless steel plate in plan view, and is laminated and bonded to the upper surface of the cavity plate 10 with the openings of the plurality of pressure chambers 16 closed. The diaphragm 30 also serves as a common electrode that opposes the plurality of individual electrodes 32 and applies an electric field to the piezoelectric layer 31 between the individual electrodes 32 and the diaphragm 30.

  The surface of the diaphragm 30 is mainly composed of lead zirconate titanate (PZT), which is a solid solution and ferroelectric material of lead titanate and lead zirconate, at a position facing the central portion of the pressure chamber 16; A piezoelectric layer 31 having a substantially elliptical planar shape that is slightly smaller than the pressure chamber 16 is formed. The piezoelectric layer 31 can be formed, for example, by cutting a piezoelectric sheet generated by firing a PZT green sheet and pasting it on the vibration plate 30. Alternatively, the piezoelectric layer 31 may be formed by depositing PZT particles on the vibration plate 30 by an aerosol deposition method (AD method), a sputtering method, or the like.

  On the surface of the piezoelectric layer 31, a plurality of individual electrodes 32 having substantially the same elliptical planar shape as the piezoelectric layer 31 are formed. These individual electrodes 32 are made of a conductive material such as gold, and are formed by screen printing or the like. Further, on the surface of the piezoelectric layer 31, a plurality of terminal portions 35 are respectively formed at one end portions (left end portion or right end portion in FIG. 2) of the plurality of individual electrodes 32. The plurality of terminal portions 35 are electrically connected to a driver IC (not shown) via a flexible wiring member such as a flexible printed wiring board. A plurality of terminal portions 35 are connected to the driver IC via the terminal portion 35. A driving voltage is selectively supplied to the individual electrodes 32.

Next, the ink ejection operation by the actuator unit 3 will be described.
When a driving voltage is selectively supplied from the driver IC to the plurality of individual electrodes 32, the individual electrodes 32 on the upper side of the piezoelectric layer 31 to which the driving voltage is supplied and the lower side of the piezoelectric layer 31 held at the ground potential. The potentials of the diaphragm 30 as the common electrode are in different states, and an electric field in the vertical direction is generated in the portion of the piezoelectric layer 31 sandwiched between the individual electrode 32 and the diaphragm 30. Then, the portion of the piezoelectric layer 31 directly below the individual electrode 32 to which the drive voltage is applied contracts in the horizontal direction orthogonal to the vertical direction that is the polarization direction. At this time, the diaphragm 30 is deformed so as to protrude toward the pressure chamber 16 as the piezoelectric layer 31 contracts, so that the volume in the pressure chamber 16 decreases and pressure is applied to the ink in the pressure chamber 16. Then, ink is ejected from the nozzle 24 communicating with the pressure chamber 16.

By the way, if bubbles are mixed in from the outside into the individual ink flow path 25 including the pressure chamber 16 and the bubbles remain in the individual ink flow path 25, the actuator unit is used during the ink discharge operation described above. 3 makes it impossible to reliably apply pressure to the ink in the pressure chamber 16, and the ink is not normally ejected from the nozzle 24. Here, in the inkjet head 1 of the present embodiment, bubbles staying in the individual ink flow path 25 by forcibly sucking out ink from the nozzles 24 by the above-described purge mechanism having the purge cap 103 (see FIG. 8). It is possible to discharge to a certain extent. However, the individual ink flow path 25 has a bent part and a part where the flow path area increases and decreases, and the flow rate of ink at the corner formed in such a part is very small. Tends to stay. The nozzle 24
The ink flow path in the vicinity of is formed so that the flow path area decreases rapidly, and in particular, bubbles tend to stay in the corner (point A in FIG. 8) in the vicinity of the nozzle 24. Therefore, it is difficult to completely discharge the bubbles staying at such corners only by the purge operation by the purge mechanism.

  Therefore, in the ink jet head 1 of the present embodiment, in order to easily discharge bubbles staying in the individual ink flow path 25, an ink flow path from the pressure chamber 16 to the nozzle 24 is included in the individual ink flow path 25. The flow path forming holes 20 to 23 to be formed are formed as follows. As shown in FIGS. 6B to 6F, the flow path forming holes 20 to 23 are formed such that their center lines are equal to the axis L of the nozzle 24. Therefore, the axis L of the nozzle 24 coincides with the axis of the flow path defined by the flow path forming holes 20-23. As shown in FIG. 6A, a pressure chamber 16 is formed in the cavity plate 10. As shown in FIG. 6 (b), in the base plate 11 immediately below the cavity plate 10, the flow path forming hole 20 is located at the position overlapping the end of the pressure chamber 16 in the paper feed direction (vertical direction in FIG. 6). It is formed in a long oval shape. Also, as shown in FIG. 6C, the uppermost manifold plate 12 has a flow path forming hole 21 having the same elliptical planar shape as the flow path forming hole 20 of the base plate 11. 20 in a plan view (viewed from a direction perpendicular to the plate), the circumferential direction of the flow path is formed at a position shifted by 45 degrees in the clockwise direction. Further, as shown in FIG. 6D, the second manifold plate 13 from the top has a flow path forming hole 22 having the same elliptical planar shape as the flow path forming holes 20, 21. The flow path forming hole 21 is formed at a position shifted by 45 degrees in a clockwise direction in plan view, and the longitudinal direction of the flow path forming hole 22 is parallel to the scanning direction (left-right direction in FIG. 6). is there. That is, the flow path forming hole 21, the flow path forming hole 20, and the center positions thereof coincide with each other on the axis L, but the flow path forming hole 21 is in each case from the direction of the flow path forming hole 20 to the axis L. It is arranged in a direction rotated 45 degrees. Moreover, although the flow path formation hole 22, the flow path formation hole 21, and the center positions thereof coincide with each other on the axis L, the flow path formation hole 22 is in each case from the direction of the flow path formation hole 21 to the axis L. It is arranged in a direction rotated 45 degrees. Further, as shown in FIG. 6 (e), the lowermost manifold plate 14 is formed with a perfectly circular flow path forming hole 23.

  The diameter of the perfect circular channel forming hole 23 is slightly shorter than the length of the short axis of the elliptical channel forming holes 20 to 22, as shown in FIGS. In addition, the flow path forming hole 23 is accommodated in the flow path forming holes 20 to 22 in a plan view. Accordingly, the main flow Fm (see FIG. 8) in which the main flow Fm (see FIG. 8) of ink will flow in the three oval flow passage forming holes 20 to 22 overlaps with the perfect circular flow passage formation hole 23 in plan view. Regions 20a, 21a, and 22a, and two tributary regions 20b, 21b, which project outward from the mainstream regions 20a, 21a, and 22a, respectively, and through which the tributaries Fs outside the mainstream Fm (see FIGS. 7 and 8) will flow. 22b. In other words, in this embodiment, the “mainstream region” refers to regions (openings) 20a, 21a, 20a, 21a, which overlap each other in the direction of the axis L of the flow path forming holes 20-22 of the base plate 11 and the manifold plates 12-13. This refers to the opening 22a. Further, the “branch region” refers to portions other than the main flow regions of the flow path forming holes 20 to 22 of the base plate 11 and the manifold plates 12 to 13.

The tributary regions 20b, 21b, and 22b formed in the oval flow passage forming holes 20 to 22 are partially different from the tributary regions of other flow passage forming holes adjacent in the vertical direction that is the stacking direction of the plates. Furthermore, the tributary regions 20b, 21b, and 22b of the three flow path forming holes 20 to 22 are sequentially shifted by 45 degrees clockwise about the axis L, and the tributary regions 20b, 21b, and 22b are sequentially shifted. Are arranged in a spiral. Since each of the flow path forming holes 20 to 22 is an ellipse, the points 20w, 21w, and 22w on the major axis of the outer circumference of the ellipse are the farthest points from the center of the ellipse (and the axis L). 20w, 21w, and 22w are also shifted sequentially by 45 degrees clockwise about the axis L, and are arranged so as to draw a spiral toward the nozzle. For this reason, when the ink flows along the individual ink flow path 25 to the nozzle 24 during normal ink ejection when recording on the recording paper P or during the purge operation by the purge mechanism, the main flow Fm of the ink is the main flow region 20a, 21a and 22a flow along the axis L of the nozzle 24, while the ink tributary Fs outside the main flow flows through the spiral tributary regions 20b, 21b and 22b as shown in FIGS. The tributary Fs becomes a vortex. For this reason, the flow velocity of the ink near the wall surface of the individual ink flow path 25 is increased, and the bubbles remaining in the vicinity of the wall surface (particularly, the corner A) are surely discharged. Therefore, since it is not necessary to perform the purge operation many times to discharge the bubbles, the amount of ink discharged during the purge operation is reduced, and the ink can be used efficiently. Further, since the eddy current can be generated in the individual ink flow path 25 only by the three elliptical flow path forming holes 20 to 22 that are spirally arranged so as to be shifted from each other in the circumferential direction, This configuration is very simple, which is advantageous in terms of the manufacturing cost of the inkjet head 1.

  In this embodiment, a step is generated between the adjacent flow path forming holes 20 to 23, and bubbles are retained in the corners formed at the peripheral edge of the flow path forming holes 20 to 23 due to such a step. It's easy to do. However, in the present embodiment, the two tributary regions 20b, 21b, and 22b formed in the elliptical flow path forming holes 20 to 22 are symmetrical with respect to the axis L (the angle of 180 degrees in the circumferential direction). The ink tributary Fs is symmetrical with respect to the axis L, starting from the two tributary regions 20b of the channel forming hole 20 located at the uppermost position among the channel forming holes 20-22. The two eddy currents flow evenly in the circumferential direction. Therefore, the bubbles staying in the corners formed by the steps between the flow path forming holes 20 to 22 can be reliably discharged.

The three plates of the base plate 11, the manifold plate 12, and the manifold plate 13 are all plates having the same thickness, and the tributary regions 20b, 21b, and 22b are circumferential with respect to other tributary regions adjacent in the vertical direction. The shift angles are all equal to 45 degrees with respect to the six tributary regions 20b, 21b, and 22b. Therefore, the spiral tributary Fs generated in the tributary regions 20b, 21b, and 22b flows stably to the nozzle 24 without being bent in directions other than the spiral direction (circumferential direction). When the thicknesses of the base plate 11, the manifold plate 12, and the manifold plate 13 are different from each other, the angle at which the flow path forming holes 20 to 22 are shifted in the circumferential direction is set in proportion to the thickness, and the nozzle 24 is moved. The flow of the spiral tributary Fs can be stabilized. In addition, since the main flow regions 20a, 21a, and 22a formed in the flow path forming holes 20 to 22 are connected to the tributary regions 20b, 21b, and 22b, the main flow Fm and the tributary Fs may flow separately. And the overall flow of ink is smooth.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals, and description thereof is omitted as appropriate.

<First variation>
In the inkjet head 1 of the above embodiment, one flow path forming hole is formed in one plate, and the three flow path forming holes are shifted in the circumferential direction for each plate. A plurality of flow path forming holes that are shifted from each other in the circumferential direction may be formed in the plate. For example, in the flow path unit 2A of the modified embodiment 1 shown in FIGS. 9A to 9F, FIG. 10, and FIG. 11, the cavity plate 50, the base plate 51, the manifold plates 52, 53, 54, and the nozzle plate 55 are stacked. It has the structure which was made. Then, as shown in FIGS. 9B and 11, two flow path forming holes 60 and 61 that communicate with the base plate 51 in the vertical direction and are shifted from each other by 22.5 degrees in the circumferential direction in plan view are formed by half etching. Is formed. Similarly, as shown in FIG. 9 (c), two flow path forming holes 62 and 63 are formed in the manifold plate 52, and as shown in FIG. 9 (d), two flow paths are also formed in the manifold plate 53. Formation holes 64 and 65 are formed. These six flow path forming holes 60 to 65 all have an equal ellipse plane shape. And as shown in FIG. 10, the six flow-path formation holes 60-65 formed in the three plates 51-53 are shifted | deviated and arranged in the clockwise direction of the circumferential direction 22.5 degree | times.

  Accordingly, the main flow regions 60a, 61a, 62a, 63a, 64a, and 65a that overlap the flow passage formation hole 23 in the six flow passage formation holes 60 to 65 are arranged so as to overlap each other in plan view, while the main flow region 60a. ˜65a, the tributary regions 60b, 61b, 62b, 63b, 64b, 65b, which are respectively located outside the ˜65a, are arranged in a spiral manner in the clockwise direction, and the tributaries Fs of ink flowing through these tributary regions 60b-65b. Becomes an eddy current. As described above, by forming two or more flow path forming holes in one plate, the angle of deviation between adjacent flow path forming holes can be reduced, so that the ink tributary Fs that becomes a vortex flow is generated. It flows more stably and smoothly.

<Second Variation>
The number of tributary regions formed in one flow path forming hole is not limited to two as in the above embodiment, but may be one or may be a plurality of three or more. For example, the flow path unit 2B of the modified embodiment 2 shown in FIGS. 12A to 12F and FIG. 13 has a configuration in which a cavity plate 80, a base plate 81, manifold plates 82, 83, 84, and a nozzle plate 85 are stacked. have. Then, as shown in FIG. 12B, the base plate 81 includes a circular hole portion 86A that overlaps with the circular flow path forming hole 23 formed in the manifold plate 84, and a radially outer side from the circular hole portion 86A. A flow path forming hole 86 is formed, which is composed of three cutout portions 86B cut out. The three notches 86B are arranged at equiangular intervals in the circumferential direction of 120 degrees. Similarly, as shown in FIG. 12 (c), the manifold plate 82 is formed with a flow path forming hole 87 consisting of a circular hole 87A and three cutouts 87B, and further shown in FIG. 12 (d). As described above, the manifold plate 83 is also formed with a flow path forming hole 88 including a circular hole 88A and three notches 88B. The centers of the circular hole portions 86A, 87A and 88A and the flow path forming hole 23 are all coaxially arranged on the axis L. The apex portions of the notches 86B, 87B, and 87C are points farthest from the axis L (inner wall portions of the flow path forming holes). In this embodiment as well, the outermost part farthest from the axis L of the wall defining the flow path forming holes (through holes) of the plurality of plates is arranged so as to draw a spiral around the axis L as it approaches the liquid discharge port. Yes. As shown in FIG. 13, these three flow path forming holes 86 to 88 are arranged so as to be sequentially shifted by 15 degrees in the circumferential direction (rotated by 15 degrees around the axis L).

  Accordingly, the main flow regions 86a to 88a formed by the circular hole portions 86A to 88A are arranged so as to overlap each other, while the tributary regions 86b to 88b formed by the notches 86B to 88B are arranged in a spiral shape. And since the tributary Fs which flows through these tributary area | regions 86b-88b turns into three vortex flows symmetrical with respect to the axis line L of the nozzle 24, it flows to the nozzle 24, Therefore The bubble discharge effect similar to the said embodiment is acquired.

  As the number of tributary regions formed in one flow path forming hole is larger, the number of vortex flows is increased, and the bubbles can be discharged more reliably. However, in order to increase the number of tributary regions, the shape of the flow path forming hole becomes complicated, which is disadvantageous in terms of manufacturing cost. Therefore, it is preferable that the number of tributary regions is appropriately set in consideration of the bubble discharging effect and the manufacturing cost.

<Third Modification>
The mainstream area and the tributary area need not necessarily be connected to each other. For example, the flow path unit 2C of the modified embodiment 3 shown in FIGS. 14A to 14F and FIG. 15 has a configuration in which a cavity plate 90, a base plate 91, manifold plates 92, 93, 94, and a nozzle plate 95 are stacked. have. As shown in FIG. 14 (b), the base plate 91 has a circular hole 96A and three notches, similar to the flow path forming hole 86 (see FIG. 12 (b)) of the flow path unit 2B of the modified embodiment 2. A flow path forming hole 96 having a portion 96B (96b, 96b, 96b) is formed. Further, as shown in FIG. 14D, the second manifold plate 93 similarly has a flow path forming hole 98 having a circular hole portion 98A and three cutout portions 98B (98b, 98b, 98b). Is formed. On the other hand, the manifold plate 92 between the two plates 91 and 93 has a circular hole portion 97A that overlaps the cylindrical hole portions 96A and 98A, and is separated from the circular hole portion 97A on the radially outer side of the circular hole portion 97A. And three circular hole portions 97B (97b, 97b, 97b) formed in this manner. The three circular hole portions 97B are arranged so as to be shifted by 15 degrees in the clockwise direction with respect to the three notch portions 96B of the adjacent flow path forming holes 96, respectively. Accordingly, as shown in FIG. 15, a tributary region 96b formed by the notch 96B of the flow path forming hole 96, a tributary region 97b formed by the circular hole 97B of the flow path forming hole 97, and a flow path forming hole. A tributary region 98b formed by 98 notches 98B is arranged in a spiral shape, and the tributary Fs flowing through these tributary regions 96b, 97b, 98b flows into the nozzle 24 as a vortex. In the manifold plate 92, the portion farthest from the axis L of the wall defining the flow path forming hole 97 is not in the circular hole portion 97A but of the three circular hole portions 97B (97b, 97b, 97b). Present on the inner wall.

<Fourth Modification>
It is not always necessary that the center lines of the plurality of flow path forming holes completely coincide with each other, and it is only necessary that the flow path forming holes have a region (main flow region) overlapping in the direction of the nozzle axis L. For example, the flow path forming holes may be perfect circles having the same or different radii, and the center of the circle may be offset from the nozzle axis L. In this case, the point on the outer periphery that is the farthest from the nozzle axis L of the flow path forming holes may be displaced so as to circulate around the nozzle axis L as it approaches the nozzle.

  In the embodiment and the modified embodiment, the shape of the flow path forming hole is not limited to the flow path forming hole described in the embodiment and the modified embodiments 1 to 4, and the plurality of flow path forming holes are each an outer peripheral portion of a perfect circle. The main flow region and the spiral tributary region can be formed only by disposing the plurality of flow path forming holes in the circumferential direction if the shape has a part that partially spreads outward. Therefore, various shapes such as a polygonal shape such as a rectangle or a triangle as well as a shape having a curved portion can be adopted.

  The inkjet head 1 according to the embodiment is configured to generate a vortex in the ink flow path from the pressure chamber 16 to the nozzle 24 by the flow path forming holes 20 to 23, but from the manifold 17 to the pressure chamber 16. The ink flow path can also be configured to generate a vortex with the same configuration.

  The transfer force applying mechanism that applies the transfer force to the ink is not limited to the piezoelectric actuator unit of the above-described embodiment, and a heater used in an ink heating type inkjet head, a pump that pressurizes a liquid such as ink, and the like Various types can be adopted.

  The above-described embodiments and modifications thereof are examples in which the present invention is applied to an inkjet head that transports and discharges ink to a nozzle, but a liquid transport apparatus to which the present invention is applicable is not limited to an inkjet head. That is, it is not necessary to have a nozzle, and it is sufficient to have a discharge port. For example, a liquid transfer device that transfers a liquid such as a chemical solution or a biochemical solution inside a micro total analysis system (μTAS), a liquid transfer device that transfers a liquid such as a solvent or a chemical solution inside a microchemical system, etc. The present invention can also be applied to a liquid transfer device for transferring the liquid.

1 is a schematic perspective view of an ink jet printer according to an embodiment of the present invention. It is a top view of an inkjet head. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is the VV sectional view taken on the line of FIG. It is a top view of the plate which comprises a flow path unit, (a) shows a cavity plate, (b) shows a base plate, (c)-(e) shows a manifold plate, (f) shows a nozzle plate, respectively. FIG. 4 is an enlarged plan view of a region surrounded by an alternate long and short dash line in FIG. 3. FIG. 5 is a cross-sectional view corresponding to FIG. 4 during a purge operation. It is a top view of the plate which comprises the flow path unit which concerns on the modified form 1, (a) is a cavity plate, (b) is a base plate, (c)-(e) is a manifold plate, (f) is a nozzle plate, respectively. Show. FIG. 8 is an enlarged plan view of an inkjet head corresponding to FIG. It is the XI-XI sectional view taken on the line of FIG. It is a top view of the plate which comprises the flow-path unit which concerns on the modification 2, (a) is a cavity plate, (b) is a base plate, (c)-(e) is a manifold plate, (f) is a nozzle plate, respectively. Show. FIG. 8 is an enlarged plan view of an ink jet head corresponding to FIG. It is a top view of the plate which comprises the flow-path unit which concerns on the modified form 3, (a) is a cavity plate, (b) is a base plate, (c)-(e) is a manifold plate, (f) is a nozzle plate, respectively. Show. FIG. 8 is an enlarged plan view of an ink jet head corresponding to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3 Actuator unit 10 Cavity plate 11 Base plate 12, 13, 14 Manifold plate 15 Nozzle plates 21, 22, 23 Flow path formation holes 20a, 21a, 22a Main flow area 20b, 21b, 22b Branch area 24 Nozzle 25 Individual ink flow path 2A Flow path unit 50 Cavity plate 51 Base plates 52, 53, 54 Manifold plate 55 Nozzle plates 60, 61, 62, 63, 64, 65 Flow path forming holes 60a, 61a, 62a, 63a, 64a, 65a Main flow areas 60b, 61b, 62b, 63b, 64b, 65b Tributary area 2B Flow path unit 80 Cavity plate 81 Base plates 82, 83, 84 Manifold plate 85 Nozzle plates 86, 87 , 88 Flow path forming holes 86a, 87a, 88a Main flow areas 86b, 87b, 88b Tributary area 2C Flow path unit 90 Cavity plate 91 Base plates 92, 93, 94 Manifold plate 95 Nozzle plates 96, 97, 98 Flow path forming holes 96a, 97a, 98a Mainstream region 96b, 97b, 98b Tributary region

Claims (21)

A liquid transfer device comprising:
A channel unit having a liquid channel;
A transfer force applying mechanism for applying a transfer force to the liquid in the liquid flow path,
The flow path unit has a plurality of stacked plates each having a plurality of flow path forming holes forming at least a part of the liquid flow path,
In each of the plurality of flow path forming holes, a main flow region that substantially overlaps each other when viewed from a direction orthogonal to the plate, and a tributary region that is located outside the main flow region when viewed from a direction orthogonal to the plate. Formed,
Each of the tributary regions is provided so that the tributary regions adjacent to each other in the stacking direction of the plates partially overlap each other when viewed from a direction orthogonal to the plate, and are arranged in a spiral shape.   The liquid transfer device according to claim 1, wherein a plurality of the tributary regions are formed in one flow path forming hole.   The liquid transfer device according to claim 2, wherein the plurality of tributary regions formed in the one flow path forming hole are arranged at equiangular intervals in a circumferential direction in which the spiral is drawn.   The liquid transfer device according to claim 1, wherein the main flow region and the tributary region are connected in each flow path forming hole.   The liquid transfer device according to claim 4, wherein the flow path forming hole is formed in an oval shape elongated in one direction. The liquid transfer device according to claim 1, wherein center lines of the plurality of main flow regions coincide with each other.   The liquid transfer device according to claim 1, wherein the tributary regions are located at an equal angle to each other in the circumferential direction in which the spiral is drawn in adjacent plates. The liquid flow path includes a nozzle that discharges liquid to the outside of the flow path unit,
The liquid transfer device according to claim 1, wherein the plurality of flow path forming holes define a liquid flow path in the vicinity of the nozzle.   The liquid transfer apparatus according to claim 1, wherein the transfer force applying mechanism is an actuator unit.   2. The liquid transfer device according to claim 1, wherein a main flow of the liquid flows in the main flow region and a tributary of the liquid flows in the tributary region in the liquid flow path. A liquid transfer device comprising:
Including a laminate formed by laminating a plurality of plates each having through-holes so that the through-holes are arranged on a predetermined axis to define a flow path; A flow path unit having a liquid discharge port communicating therewith,
A transfer force applying mechanism for applying a transfer force to the liquid in the flow path,
The liquid transfer device arranged so as to draw a spiral around the axis as the outermost part farthest from the axis of the walls defining the through holes of the plurality of plates approaches the liquid discharge port.   The liquid according to claim 11, wherein each of the through holes formed in the plurality of plates is elliptical, the center of the ellipse is located on the axis, and the rotation angle of the ellipse with respect to the axis is different in the plurality of plates. Transfer device.   12. The through hole formed in the plurality of plates is rotationally symmetric, the center of rotational symmetry is located on the axis, and the rotation angle of the through hole with respect to the axis is different in the plurality of plates. Liquid transfer device.   The liquid transfer device according to claim 11, wherein the through hole includes a plurality of holes.   The liquid transfer device according to claim 11, wherein the through hole of each plate has a main flow region overlapping with through holes of a plurality of plates and a tributary region overlapping only between adjacent plates.   The liquid transfer device according to claim 15, further comprising another plate that communicates with the liquid discharge port and has a through hole corresponding to only the mainstream region.   The liquid transfer device according to claim 15, further comprising another plate in which nozzle holes are formed, wherein the nozzle holes are the liquid discharge ports. It is a manufacturing method of the liquid transfer device according to claim 11,
A plurality of plates each formed with a through hole are arranged on a predetermined axis to define a flow path, and the outermost part farthest from the axis of the wall defining the through hole is Forming a flow path unit by stacking so as to draw a spiral around the axis as approaching the liquid discharge port; and
Providing a transfer force applying mechanism for applying a transfer force to the liquid in the flow path.   The plurality of plates include first to third plates in which first to third through holes having the same shape are formed, and the rotation angles of the first to third through holes with respect to the axis are different from each other. Item 19. A method for producing a liquid transfer device according to Item 18.   The plurality of plates include first to third plates in which first to third through holes are formed, respectively, and the shape of the first through hole is different from the shape of the second through hole. Manufacturing method. Furthermore, the manufacturing method of the liquid transfer apparatus of Claim 18 including providing a pressure chamber between a flow-path unit and a transfer force provision mechanism.

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