JP3719169B2 - Inkjet printer head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of a piezoelectric type ink jet printer head.
[0002]
[Prior art]
In the prior art on-demand type piezoelectric ink jet printer head, as described in JP-A-8-25631, a nozzle plate having a plurality of nozzles formed in a row is arranged between a diaphragm and a diaphragm. A spacer plate provided with a pressure chamber, a reservoir, an ink supply port connecting them, a flow path for distributing ink from the ink tank to each reservoir, and the like, and the diaphragm And a piezoelectric element unit for selectively driving each pressure chamber, contracting and expanding the pressure chamber, sending ink in the pressure chamber toward the nozzle, and discharging ink droplets from the nozzle onto the recording medium. An inkjet printer head is disclosed.
[0003]
As disclosed in the above publication, in order to improve the printing performance and reduce the size of the head, it is necessary to narrow the interval between the nozzle rows, and on the other hand, the energy of the piezoelectric element unit is used efficiently. In order to do so, the pressure chambers must be made as large as possible, and these are conflicting requirements. In order to solve this problem, it is necessary to increase the volume of the pressure chamber by reducing the arrangement interval of the pressure chambers and increasing the longitudinal dimension of the pressure chambers. If the width of the wall (girder) separating (dividing) adjacent pressure chambers is shortened as much as possible in accordance with this requirement, the rigidity of the wall (girder) is reduced, and the spacer plate in the manufacturing process is reduced. There is a problem that the wall portion is easily plastically deformed during handling, and the manufacturing yield of the inkjet head is deteriorated.
[0004]
In order to solve this problem, in the above prior art, the pressure chamber in the spacer plate made of a silicon single crystal material is formed long from the reservoir along the nozzle direction by etching, and in the middle in the longitudinal direction, It has been proposed to form a thin-walled bridge that connects one wall surface and the other wall surface of the pressure chamber so as to extend obliquely from the reservoir toward the nozzle.
[0005]
[Problems to be solved by the invention]
However, in the said structure, the angle of the base part of a connection with the wall surface of the pressure chamber of the said bridge is an obtuse angle with respect to the one wall surface, On the other hand, it becomes an acute angle with respect to the other wall surface. By the way, the velocity distribution of the ink flow flowing along the longitudinal direction of the pressure chamber follows the general principle of laminar flow or turbulent flow of viscous fluid in hydrodynamic (hydrodynamic), and the velocity is zero on the wall surfaces. It is shown in a convex curve shape where the speed is maximum at a substantially central portion in between.
[0006]
Therefore, in any case, since the speed of the ink flow in the vicinity of the connection root between the upstream side surface of the ink flow in the bridge and the wall surface is extremely low, the bubbles carried on the ink are in the vicinity of the connection root. Easy to stay. In particular, in the portion where the angle of the connecting root portion is an acute angle, when the number of bubbles staying increases, the bubble grows to a large volume, and when the bubbles reach the nozzle, a so-called nozzle clogging occurs, resulting in poor printing. The problem of becoming could not be solved.
[0007]
It is a technical object of the present invention to provide an ink jet printer head that solves such problems.
[0008]
[Means for Solving the Problems]
In order to achieve this technical problem, an ink jet printer head according to the first aspect of the present invention includes a cavity plate unit including a plurality of nozzles and pressure chambers for each of the nozzles arranged in a row in a first direction; In the ink jet printer head having an active part that can be selectively driven for each pressure chamber, and an actuator for ejecting ink, the first direction is provided in the middle part of each pressure chamber. A pair of side walls extending along the intersecting second direction is connected by a thin-walled bridge, and the upstream side wall facing the ink flow in the nozzle direction in each bridge and the pair of side walls The angle formed is set to be an obtuse angle.
[0009]
According to a second aspect of the present invention, in the inkjet printer head according to the first aspect, the upstream side wall facing the ink flow in the nozzle direction in each bridge is substantially the same between the pair of side walls. It is formed so as to be inclined toward the downstream side of the ink flow in the nozzle direction as it goes closer to the center.
[0010]
According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, the shape in plan view of a substantially central portion between the pair of side walls in each bridge is set in the nozzle direction. It is formed in a substantially V shape or U shape toward the downstream side of the ink flow.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 7 show a piezoelectric ink jet printer head of the present invention. In these drawings, a flexible flat cable 40 is overlapped and joined to the upper surface of the plate-type piezoelectric actuator 20 joined to the cavity unit 10 for connection to an external device. It is assumed that the ink is ejected downward from the nozzle 54 opened on the lower surface side of FIG.
[0012]
The cavity unit 10 according to the embodiment is configured as shown in FIGS. 3 and 4. That is, it is a structure in which five thin plates of the nozzle plate 43, the damper plate 11, the manifold plate 12, the spacer plate 13, and the cavity plate 14 are stacked by bonding and bonded together. In the embodiment, each of the plates 11, 12, 13, 14 excluding the nozzle plate 43 is made of 42% nickel alloy steel plate and has a thickness of about 50 μm to 150 μm. Each plate is formed with an opening or a recess constituting each of the following flow paths or chambers by etching or the like. The nozzle plate 43 is provided with nozzles 54 for ejecting ink having a small diameter along a first direction (long side direction) of the nozzle plate 43 in a two-row staggered arrangement. That is, a large number of nozzles 54 are formed in a staggered arrangement at intervals of a minute pitch P along two reference lines 43a and 43b parallel to the first direction of the nozzle plate 43.
[0013]
The pressure chambers 16 to be described later corresponding to the nozzles 54 and the active portions of the piezoelectric elements in the piezoelectric actuator 20 to be described later are arranged so as to overlap and correspond to each other in plan view of each plate. The pressure chambers 16 are formed so as to extend in a direction intersecting (orthogonal) with the first direction, and the row of pressure chambers 16 extends along the first direction. In the manifold plate 12, a pair of manifold chambers 12a and 12a serving as ink passages are formed so as to extend along both sides of the row of the nozzles 54. In this case, each manifold chamber 12a extends so as to overlap the row of pressure chambers 16 and straddle the row of pressure chambers 16 in plan view of the plate (see FIGS. 3 and 4).
[0014]
Each manifold chamber 12a in the manifold plate 12 is formed by a recess opened toward the upper spacer plate 13 leaving a thin bottom plate 12b on the lower surface side of the manifold plate 12. And an upper surface of the manifold plate 12 are bonded to each other (see FIG. 6).
[0015]
The cavity plate 14 has a plurality of narrow pressure chambers 16 extending in a second direction (short side direction) orthogonal to a center line along the long side (first direction). It is installed. As will be described later, most of the pressure chambers 16 (excluding the other end 16b and the bridge 57) are formed so as to penetrate in the thickness direction of the cavity plate 14 by etching, and the cavity plate 14 and the spacer plate 13 are formed. The sealed pressure chamber 16 is formed by being sandwiched by an adhesive sheet 41 made of a non-ink-permeable synthetic resin material as an adhesive layer on the entire lower surface (wide surface facing the pressure chamber 16) of the piezoelectric actuator 20. (See FIG. 6).
[0016]
When parallel longitudinal reference lines 14a and 14b are set on both the left and right sides of the center line along the first direction of the cavity plate, the tip 16a of the pressure chamber 16 on the left side of the center line is the left longitudinal reference line. On the contrary, the tip 16a of the pressure chamber 16 on the right side of the longitudinal center line is located on the right longitudinal reference line 14b, and the tips 16a of the left and right pressure chambers 16 are alternately arranged. Therefore, the pressure chambers 16 on the left and right sides are alternately arranged so as to extend in opposite directions to each other (see FIG. 4).
[0017]
The tip 16a of each pressure chamber 16 has a small diameter that is formed in the staggered arrangement of nozzles 54 in the nozzle plate 43 in the staggered arrangement of the spacer plate 13, the manifold plate 12, and the damper plate 11. The through holes 17 and 17 communicate with each other. On the other hand, the other end 16 b of each pressure chamber 16 communicates with the manifold chamber 12 a in the manifold plate 12 through through holes 18 drilled in the left and right side portions of the spacer plate 13. As shown in FIG. 4, the other end 16b is recessed so as to open only on the lower surface side of the cavity plate.
[0018]
In the middle part of the pair of wall surfaces 16c, 16c extending along the longitudinal direction (the second direction) in each pressure chamber 16 (see FIGS. 2 and 4), the width dimension between the adjacent pressure chambers 16, 16 is used. A thin bridge 61 for reinforcing the narrow girder 60 of w1 is formed to be connected. The ink flow velocity distribution upstream of the bridge 61 is zero at the side walls 16c and 16c, and is a convex curve distribution that is maximum at the center between the side walls 16c and 16c. It shall draw a curve.
[0019]
According to the present invention, as shown in FIGS. 5A and 5B, the flow of ink in the direction of the nozzle 54 in the bridge 61 (in other words, the tip direction 16a) (the arrow in FIG. 5A). A depression angle θ1 formed by the upstream side wall 61a facing to (indicated by A) and the pair of wall surfaces 16c, 16c of the pressure chamber is an obtuse angle larger than 90 degrees, preferably 110 degrees to 160 degrees. Set.
[0020]
Further, the upstream side wall 61a facing the ink flow in the direction of the nozzles in each bridge 61 (indicated by the arrow A in FIG. 5 (a)) is closer to the substantially central portion between the pair of side walls 16c, 16c. As it goes to, the ink is inclined so as to face the downstream side of the ink flow in the nozzle direction (direction of the tip 16a of the pressure chamber). By forming in this way, the connecting root portion between the bridge 61 and the side walls 16c and 16c does not become a pocket portion where the ink flow stays. Therefore, when the suction means is pressed against the nozzle plate to suck out the bubbles accumulated in the manifold or the like, the ink 62 on the side close to the side wall 16c among the bubbles 62 conveyed from the upstream side of the ink flow Even if the flow speed of the bubble 62 is low, the bubble 62 does not stay at the connecting root portion between the bridge 61 and the side walls 16c and 16c, and extends between the side walls 16c and 16c along the upstream side wall 61a. Since it can move smoothly to the center side, the bubbles get over the upper surface of the bridge 61 at a location where the ink flow speed is large (the center location) and flow downstream (from the tip 16a side of the pressure chamber 16) to be removed from the nozzle. It can be done.
[0021]
The shape of each bridge 61 in plan view is based on the configuration described above, and the shape in plan view of the substantially central portion between the pair of side walls 16c, 16c in each bridge is the downstream side of the ink flow in the nozzle direction. You may form in a substantially V shape (refer FIG. 5 (a)) or U shape (refer FIG. 8) toward the front-end | tip 16a side of the pressure chamber 16. FIG. Note that the depression angle θ2 of the connecting root portion between the downstream side wall 61b of the ink flow in the bridge 61 and the pair of side walls 16c, 16c may be set to an obtuse angle as shown in FIG. Thus, if both depression angles θ1 and θ2 are obtuse, or if the width dimension of the bridge 61 along the ink flow on the side close to the pair of side walls 16c and 16c is made larger than the dimension on the center side, the width relative to the side wall 16c of the bridge 61 is increased. The dimension along the ink flow direction of the connecting root can be increased, the strength of the connecting portion is increased, and it is possible to contribute to increasing the strength (rigidity) of the beam 60 between the adjacent pressure chambers 16 and 16.
[0022]
In the processing method of forming each bridge 61 in a thin shape, half etching is performed so as to leave only the thickness t1. In the embodiment, the plate thickness of the cavity plate 14 is 50 μm, the thickness of the bridge 61 (wall thickness t1) is 20 μm, the width of the pressure chamber 16 between the pair of side walls 16c and 16c is 250 μm, and the width dimension of the girder is 80 μm. did.
[0023]
Note that a filter 29 for removing dust in the ink supplied from an ink tank (not shown) thereabove is stretched on the upper surface of the supply hole 19a formed in one end of the uppermost cavity plate 14. It is installed.
[0024]
As a result, ink that has flowed into the left and right manifold chambers 12a and 12a from supply holes 19a and 19b drilled in one end of the cavity plate 14 and spacer plate 13 from an ink supply source (ink tank) (not shown). Is distributed through the through holes 18 into the pressure chambers 16 and then from the pressure chambers 16 to the nozzles 54 corresponding to the pressure chambers 16 through the through holes 17. (See FIGS. 3 and 6).
[0025]
On the other hand, on the upper surface of the damper plate 11, a damper chamber 11a having substantially the same shape in plan view is formed in a recess so as to open upward at substantially the same position as each manifold chamber 12a. Therefore, in a state where the manifold plate 12 and the damper plate 11 are joined, the manifold chamber 12a and the damper chamber 11a are separated by the bottom plate 12b. Each damper chamber 11a is formed with a communicating portion 55 that swells outward from the outer peripheral edge of each manifold chamber 12a in plan view.
[0026]
The damper plate 11, the manifold plate 12, the spacer plate 13, and the cavity plate 14 are laminated, bonded and fixed with an adhesive or the like, and the upper surface of the pace plate 14 (farthest from the nozzle plate 43) from the communication portion 55. A communication hole 56 as an air escape hole that can communicate with the side surface) is previously formed in each of the plates 12, 13, and 14. In order to exhibit the damper effect by the damper chamber 11a, in the embodiment, about 5 μm is preferable.
[0027]
As shown in FIGS. 3 and 6, when a pair of damper chambers 11a, 11a is formed in the damper plate 11, a communication portion 55 and a communication hole 56 are formed corresponding to each damper chamber 11a. In addition, when the piezoelectric actuator 20 (to be described later) is fixed to the upper surface of the pace plate 14 with an adhesive, the communication hole 56 opens so as not to be blocked by the piezoelectric actuator 20 and the adhesive. Should be set.
[0028]
On the other hand, the piezoelectric actuator 20 has a structure in which nine piezoelectric sheets 21a, 21b, 21c, 21d, 21e, 21f, 21g, 22, 23 are stacked, as shown in FIGS. Among the piezoelectric sheets, the lowermost piezoelectric sheet 22 and the upper surfaces (wide surfaces) of the odd-numbered piezoelectric sheets 21b, 21d, and 21f counted upward are narrowed for each location of each pressure chamber 16 in the cavity unit 10. The individual electrodes 24 having a width are formed in a row along a first direction (long side direction), and each individual electrode 24 is a length of each piezoelectric sheet along a second direction orthogonal to the first direction. It extends to the vicinity of the edge of the side. A common electrode 25 common to the plurality of pressure chambers 16 is formed on the upper surfaces (wide surfaces) of the even-numbered piezoelectric sheets 21a, 21c, 21e, and 21g from the bottom.
[0029]
In the embodiment, the width of each individual electrode 24 is set slightly narrower than the wide portion of the corresponding pressure chamber 16 in plan view.
[0030]
On the other hand, since the pressure chambers 16 are arranged in two rows along the first direction (long side) on the central side of the short side of the cavity plate 14, the common electrode 25 is It is formed in a substantially rectangular shape in plan view extending along the long side at the center in the short side direction of the even-numbered piezoelectric sheets 21a, 21c, 21e, 21g so as to integrally cover the pressure chambers 16, 16 in the row. At the same time, in the vicinity of the end edges of the pair of short sides of the even-numbered piezoelectric sheets 21a, 21c, 21e, 21g, lead portions 25a, 25a extending substantially over the entire length of the end edges are integrally formed.
[0031]
The individual electrodes 24 are disposed on the surface of the even-stage piezoelectric sheets 21a, 21c, 21e, and 21g near the edge of the long side where the common electrode 25 is not formed. The dummy individual electrodes 26 having the same width as the individual electrodes 24 and a short length are formed at the same vertical position (corresponding position). In this case, as shown in FIG. 7, the end of each dummy individual electrode 26 has an appropriate gap dimension with respect to the side edge of the common electrode 25 in the first direction (the direction along the long side). Separated. The length of every other layer of the dummy individual electrode 26 is set to be long and short like L2 and L3 (<L2), and the pattern breaks between the end of the dummy individual electrode 26 and the side edge of the common electrode 25 are cut. The position may be shifted in the second direction (short-side direction) of the piezoelectric sheet every other stacked piezoelectric sheet. In the embodiment, the length L2 of the dummy individual electrode 26 in the second layer (piezoelectric sheet 21a) and the sixth layer (piezoelectric sheet 21e) from the bottom is set to the fourth layer (piezoelectric sheet 21c) and the eighth layer. The gap is set to be longer than the length L3 of the dummy individual electrode 26 in the layer (piezoelectric sheet 21g).
[0032]
On the other hand, on the upper surface (wide surface) of the lowermost piezoelectric sheet 22 and the odd-numbered piezoelectric sheets 21b, 21d, 21f counted upward (positions corresponding to the leading portions 25a, 25a (the same vertical position, piezoelectric sheet) The dummy common electrode 27 is formed in the vicinity of the edge of the short side of the pair.
[0033]
On the upper surface of the uppermost top sheet 23, a surface electrode 30 for each of the individual electrodes 24 and a surface electrode 31 for the common electrode 25 are provided along the edge of the long side. (See FIG. 2).
[0034]
Further, except for the lowermost piezoelectric sheet 22, all the other piezoelectric sheets 21a, 21b, 21c, 21d, 21e, 21f, and 21g and the top sheet 23 have the surface electrodes 30 and the corresponding ones. A through hole 32 is formed so that the individual electrode 24 and the dummy individual electrode 26 at the same position (the same vertical position) communicate with each other. Similarly, the at least one surface electrode 31 (in the embodiment, the surface electrode 31 at the four corners of the top sheet 23) and the corresponding common electrode 25 or the lead portion 25a at the corresponding position (the same vertical position) are provided. Through holes 33 are formed so as to communicate with each other, and the individual electrodes 24 of each layer and the surface electrodes 30 corresponding to the layers are electrically connected to each other through the conductive material filled in the through holes 32 and 33. In the same manner, the common electrodes 25 of each layer and the surface electrode 31 at the corresponding position are electrically connected to each other.
[0035]
As a result, the plurality of piezoelectric sheets 21 and the top sheet 23 stacked vertically are electrically connected to the position of the surface electrode 30 with the individual electrodes 24 and the dummy individual electrodes 26 at the same upper and lower positions. A plurality of common electrodes 25 and dummy common electrodes 27 are electrically connected to the surface electrode 31 (see FIGS. 2 and 7).
[0036]
Then, an adhesive sheet 41 made of an ink non-permeable synthetic resin material as an adhesive layer is pasted in advance on the entire lower surface (the wide surface facing the pressure chamber 16) of the plate-type piezoelectric actuator 20 having such a configuration. Next, the individual electrodes 24 in the piezoelectric actuator 20 are bonded and fixed to the cavity unit 10 so as to correspond to the pressure chambers 16 in the cavity unit 10 (see FIG. 6). Further, when the flexible flat cable 40 is pressed against the upper surface of the piezoelectric actuator 20, various wiring patterns (not shown) in the flexible flat cable 40 become the surface electrodes 30, 31. Electrically joined to the
[0037]
The material of the adhesive layer such as the adhesive sheet 41 is at least ink impermeable and has electrical insulation, and is mainly composed of a nylon or dimer acid based polyamide resin. Polyamide-based hot-melt adhesives or polyester-based hot-melt adhesives may be used. However, after applying a polyolefin-based hot-melt adhesive to the wide surface of the piezoelectric actuator 20, Alternatively, the cavity unit 10 may be bonded and fixed. The thickness of the adhesive layer is about 1 μm.
[0038]
In this configuration, by applying a voltage between any individual electrode 24 among the individual electrodes 24 in the piezoelectric actuator 20 and the common electrode 25, the individual electrode 24 to which the voltage is applied in the piezoelectric sheet 21 is applied. It becomes an active part of the piezoelectric element in which distortion in the stacking direction due to piezoelectricity occurs in the corresponding part. The active portion of the piezoelectric element in the piezoelectric actuator 20 and the pressure chamber 16 for each nozzle 54 overlap each other in plan view of each plate.
[0039]
Then, the internal volume of the pressure chamber 16 corresponding to each individual electrode 24 is reduced by the distortion of the active portion, so that the ink in the pressure chamber 16 is ejected from the nozzle 54 in the form of droplets, Predetermined printing is performed.
[0040]
As described above, by interposing the adhesive layer so as to cover all the pressure chambers 16 between the piezoelectric actuator 20 and the cavity unit 10, the adhesive layer plays a role of a film that does not allow ink to permeate. At the same time, the piezoelectric actuator 20 and the cavity unit 10 can be firmly fixed. And since it is an adhesive agent, the thickness of the layer can be formed extremely thin compared with the conventional diaphragm plate, and there exists an effect that an inkjet printer head can be manufactured at low cost. In addition, since the piezoelectric actuator 20 is formed by laminating the piezoelectric sheets 21 and 22 extending over the plurality of pressure chambers 16, the rigidity of the entire piezoelectric actuator 20 is increased, and vibrations such as those of a conventional diaphragm plate do not occur. , Driving at a high frequency can be made possible.
[0041]
When the active portion of the piezoelectric actuator 20 is selectively driven, the active portion is elastically deformed so as to curve the plane of the plate portion of the piezoelectric actuator 20, and the predetermined pressure chamber 16 is selectively pressurized. Then, the pressure is transmitted to the corresponding nozzle 54, and printing is executed by ejecting ink droplets.
[0042]
In the present invention, the driving means (actuator) of the active part for activating the pressure chamber may be provided with individual piezoelectric elements for each pressure chamber.
[0043]
[Operation and effect of the invention]
As described above, the ink jet printer head according to the first aspect of the present invention includes a cavity plate unit having a plurality of nozzles and pressure chambers for each nozzle arranged in a row in the first direction, In an ink jet printer head having an active portion that can be selectively driven for each pressure chamber, and an actuator that ejects ink, the intermediate portion of each pressure chamber intersects the first direction. A pair of side walls extending along the second direction is connected by a thin-walled bridge, and an angle formed between the upstream side wall facing the ink flow in the nozzle direction in each bridge and the pair of side walls. Is set to have an obtuse angle.
[0044]
With this configuration, the bubbles that flow along the vicinity of the side wall of the pressure chamber having a low ink flow velocity are connected to the upstream side wall facing the ink flow toward the nozzle in the bridge and the pair of side walls. Even if it hits the base, it does not become a pocket where the flow stays, so it can move to the center side in the width direction of the pressure chamber, and bubbles can get over the bridge at a place where the flow of ink is fast. Therefore, even during the suction purge, there is an effect that bubbles are not accumulated due to bubbles remaining in the pressure chamber and growing.
[0045]
According to a second aspect of the present invention, in the inkjet printer head according to the first aspect, the upstream side wall facing the ink flow in the nozzle direction in each bridge is substantially the same between the pair of side walls. As it goes closer to the center part, it is formed so as to be inclined toward the downstream side of the ink flow in the nozzle direction, so the width of the pressure chamber from the connecting root part where the depression angle between the side wall and the bridge is an obtuse angle. The bubbles are more easily moved toward the center of the direction, and the action and effect of the invention of claim 1 can be further enhanced.
[0046]
According to a third aspect of the present invention, in the ink jet printer head according to the first or second aspect, the shape in plan view of a substantially central portion between the pair of side walls in each bridge is set in the nozzle direction. An upstream side wall that is formed in a substantially V shape or U shape toward the downstream side of the ink flow, and faces the ink flow in the nozzle direction in the bridge by such a planar view shape. Can be made smooth toward the central portion in the width direction of the pressure chamber, and the action of the bubbles over the bridge and moving downstream of the ink flow can be further enhanced.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a piezoelectric inkjet printer head according to an embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing one end of a cavity unit and a piezoelectric actuator.
FIG. 3 is an exploded perspective view of the cavity unit.
FIG. 4 is a partially enlarged perspective view of a cavity unit.
5A is a plan view of a principal part showing a connection angle between both side walls of a pressure chamber and a bridge, and FIG. 5B is a cross-sectional view taken along line Vb-Vb in FIG. 5A.
6 is an enlarged side sectional view of the piezoelectric ink jet printer head taken along line VI-VI in FIG.
FIG. 7 is an exploded perspective view of the piezoelectric actuator.
FIG. 8 is an enlarged plan view showing a second embodiment of the bridge.
FIG. 9 is an enlarged plan view showing a third embodiment of the bridge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Cavity unit 11 Damper plate 11a Damper chamber 12 Manifold plate 12a Manifold chamber 13 Spacer plate 14 Cavity plate 16 Pressure chamber 16a Tip 16b The other end 16c, 16c A pair of side walls 20 Piezoelectric actuator 30, 31 Surface electrode 54 Nozzle 55 Communication part 56 Communication Hole 43 Nozzle plate 54 Nozzle 60 Girder 61 Bridge 61a Upstream side wall 61b Downstream side wall

Claims (3)

A cavity plate unit having a plurality of nozzles and pressure chambers for each nozzle arranged in a row in the first direction, and an active portion that can be selectively driven for each pressure chamber, and ejecting ink. In an inkjet printer head made by stacking actuators,
In the middle of each pressure chamber, a pair of side walls extending along a second direction intersecting the first direction is connected by a thin bridge,
An ink jet printer head, wherein an angle formed between an upstream side wall facing the ink flow in the nozzle direction in each bridge and the pair of side walls is set to be an obtuse angle. The upstream side wall facing the ink flow in the nozzle direction in each bridge is directed toward the downstream side of the ink flow in the nozzle direction as it goes closer to a substantially central portion between the pair of side walls. 2. The ink jet printer head according to claim 1, wherein the ink jet printer head is inclined. The shape in plan view of a substantially central portion between the pair of side walls in each bridge is formed in a substantially V shape or U shape toward the downstream side of the ink flow in the nozzle direction. The inkjet printer head according to claim 1 or 2.

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