JP2015136870A - Liquid discharge device, and manufacturing method of liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device having a piezoelectric actuator having grooves on a piezoelectric layer, capable of suppressing variations in liquid discharge speeds among plural nozzles, by changing positions and shapes of the grooves.SOLUTION: A piezoelectric actuator 21 has plural grooves 51, 52 formed on circumferential parts of plural pressure chambers 37, of a piezoelectric layer 44. The plural grooves 51, 52 have different positions or shapes according to parameters related to ink discharge speeds corresponding nozzles 34, respectively.

Description

  The present invention relates to a liquid ejection apparatus and a method for manufacturing the liquid ejection apparatus.

  As a liquid ejecting apparatus that ejects liquid, Patent Document 1 discloses an ink jet head that ejects ink droplets from nozzles. The inkjet head of Patent Document 1 includes a flow path unit in which an ink flow path including a plurality of nozzles is formed, and a piezoelectric actuator (actuator unit) joined to the flow path unit.

  The flow path unit has a plurality of pressure chambers respectively communicating with the plurality of nozzles. The piezoelectric actuator includes four piezoelectric layers (piezoelectric sheets) arranged so as to cover the plurality of pressure chambers, and a plurality of individual layers arranged on the upper surface of the uppermost piezoelectric layer so as to face the plurality of pressure chambers. An electrode and a common electrode disposed on the lower surface of the uppermost piezoelectric layer. In addition, a groove is formed in the peripheral portion of each pressure chamber on the upper surface of the uppermost piezoelectric layer.

  In this piezoelectric actuator, when a drive voltage is applied between the individual electrode and the common electrode, the portion of the uppermost piezoelectric layer sandwiched between the individual electrode and the common electrode contracts in the plane direction, and The piezoelectric layer is deformed so as to be convex toward the pressure chamber. Since the volume of the pressure chamber changes due to the deformation of the piezoelectric layer, the pressure of the ink in the pressure chamber rises and the ink is ejected from the nozzle.

JP 2003-311954 A

  Although not clearly described in Patent Document 1, a groove is formed around the pressure chamber of the piezoelectric layer to promote deformation of the portion of the piezoelectric layer facing each pressure chamber. Can do. When the deformation amount of the piezoelectric layer increases, the volume change amount of the pressure chamber increases, and a large pressure is applied to the ink in the pressure chamber, so that the ink ejection speed from the nozzle increases.

  By the way, in the liquid discharge apparatus as disclosed in Patent Document 1, it is ideal that the discharge speed and discharge volume of the liquid discharged from the nozzles are uniform among the plurality of nozzles. There is a problem that the discharge speed may vary due to various factors.

  An object of the present invention is to suppress variation in liquid discharge speed among a plurality of nozzles in a liquid discharge apparatus having a piezoelectric actuator in which grooves are formed in a piezoelectric layer by changing the position or shape of the grooves. It is in.

Means for Solving the Problems and Effects of the Invention

A liquid ejection apparatus according to a first aspect of the present invention includes a flow channel structure in which a liquid flow channel is formed, including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, and the flow channel structure. A piezoelectric actuator,
The piezoelectric actuator includes: a piezoelectric layer disposed to cover the plurality of pressure chambers; a plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers; and the piezoelectric layer A common electrode disposed on the opposite side of the plurality of individual electrodes and opposed to the plurality of individual electrodes, and a plurality of grooves formed in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer, respectively The at least two or more grooves included in the plurality of grooves have different positions or shapes depending on parameters related to the discharge speed of the liquid from the corresponding nozzle. It is.

  If a groove is formed around the pressure chamber of the piezoelectric layer, the deformation of the portion of the piezoelectric layer facing the pressure chamber increases, and the volume change amount of the pressure chamber increases. Therefore, the discharge speed of the liquid discharged from the nozzle can be increased.

  Furthermore, in the present invention, at least two or more grooves among the plurality of grooves respectively formed in the peripheral portions of the plurality of pressure chambers are positioned or in accordance with a parameter related to the liquid ejection speed from the corresponding nozzle. The shape is different. In other words, even when the liquid discharge speed varies among the plurality of nozzles, the discharge speed is corrected by changing the positions or shapes of the two or more grooves. Variation can be reduced.

  In the liquid ejection device according to a second aspect of the present invention, in the first aspect, each of the at least two or more grooves includes the two nozzles communicating with the two pressure chambers adjacent to the groove. The position or shape differs according to the parameter.

  When one groove is provided close to each of the two pressure chambers, this groove affects the volume change amount of the two pressure chambers, and hence the discharge speed of the liquid of each of the two nozzles. Therefore, if the position or shape of the groove is determined based only on the parameters of the nozzle communicating with one of the two pressure chambers adjacent to the groove, the other pressure chamber formed by this groove On the other hand, since the influence on the communicating nozzle is not taken into consideration, the discharge speed variation may increase. Therefore, in the present invention, each of the two or more grooves differs in position or shape depending on a parameter related to the discharge speed of each of the two nozzles communicating with the two pressure chambers adjacent to the groove. ing.

  In the first invention, the positions of the at least two or more grooves may be different according to the parameters (third invention). The at least two or more grooves may have different lengths according to the parameters (fourth invention). Alternatively, the at least two or more grooves may have different depths according to the parameters (fifth invention).

  In the first invention, the parameter may include a positional shift amount of the pressure chamber and the individual electrode in the surface direction of the piezoelectric layer (sixth invention). The parameter may include a capacitance of an active portion, which is a portion of the piezoelectric layer sandwiched between the individual electrode and the common electrode (seventh invention). The parameter may include a diameter of the discharge port of the nozzle (eighth invention). Alternatively, the parameter may include the viscosity of the liquid ejected from the nozzle (ninth invention).

A liquid ejection apparatus according to a tenth aspect of the present invention includes a plurality of liquid ejection units, and each liquid ejection unit includes a plurality of nozzles and a plurality of pressure chambers that respectively communicate with the plurality of nozzles. A flow path structure, and a piezoelectric actuator provided in the flow path structure,
The piezoelectric actuator includes: a piezoelectric layer disposed to cover the plurality of pressure chambers; a plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers; and the piezoelectric layer A common electrode disposed on the opposite side of the plurality of individual electrodes and opposed to the plurality of individual electrodes, and a plurality of grooves formed in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer, respectively Have
The position or shape of the groove of the piezoelectric actuator differs between the plurality of liquid discharge units in accordance with a parameter related to the liquid discharge speed from the nozzle.

  The liquid ejection apparatus of the present invention includes a plurality of liquid ejection units. Further, the position or shape of the groove of the piezoelectric actuator differs among the plurality of liquid ejection units in accordance with the parameter relating to the liquid ejection speed from the nozzle. In other words, even when there is a variation in the discharge speed of the liquid from the nozzles among the plurality of liquid discharge units, the discharge speed is corrected by changing the position or shape of the groove between the plurality of liquid discharge units. The variation in the discharge speed among the plurality of liquid discharge units can be reduced.

According to an eleventh aspect of the present invention, there is provided a liquid ejection device manufacturing method including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, each having a liquid channel, and the channel structure. A piezoelectric actuator provided in the
The piezoelectric actuator includes a piezoelectric layer disposed in the flow path structure so as to cover the plurality of pressure chambers, and a plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers, respectively. And a common electrode that is disposed on the opposite side of the plurality of individual electrodes across the piezoelectric layer and that faces the plurality of individual electrodes, and is formed in a portion of the piezoelectric layer that surrounds the plurality of pressure chambers, respectively. A plurality of grooves, and a method for manufacturing a liquid ejection device,
Forming a plurality of grooves in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer, respectively,
In the groove forming step, a groove forming condition related to a position or a shape of the groove corresponding to the pressure chamber communicating with the nozzle is determined based on a parameter related to a liquid discharge speed for each nozzle, The groove is formed based on the determined groove forming condition.

  In the present invention, the conditions for forming grooves formed around the pressure chambers communicating with the nozzles are adjusted based on the parameters relating to the discharge speed for each nozzle. Therefore, even when the liquid discharge speed varies among the plurality of nozzles, by adjusting the formation conditions of the grooves formed around the pressure chamber according to the variation in the discharge speed, Variations in discharge speed can be reduced.

1 is a schematic plan view of an ink jet printer according to an embodiment. It is a top view of an inkjet head. It is the A section enlarged view of FIG. 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. FIG. 6 is a partially enlarged view of FIG. 5 (change of groove position). It is a graph which shows the relationship between a groove position and the volume variation | change_quantity of a pressure chamber. It is a figure which shows the manufacturing process of an inkjet head. It is a partial enlarged plan view of an ink jet head of a modified form. It is a fragmentary sectional view of an ink jet head of another modification. It is a fragmentary sectional view of an ink jet head of another modification. It is a fragmentary sectional view of an ink jet head of another modification. It is a schematic plan view of the inkjet printer of another modification.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic plan view of the ink jet printer of the present embodiment. First, a schematic configuration of the inkjet printer 1 will be described with reference to FIG. In the following, the front side in FIG. 1 is defined as the upper side, and the other side of the page is defined as the lower side, and the explanation will be made using direction words “up” and “down” as appropriate.

(Schematic configuration of the printer)
As shown in FIG. 1, the inkjet printer 1 includes a platen 2, a carriage 3, an inkjet head 4, a transport mechanism 5, a control device 6, and the like.

  On the upper surface of the platen 2, a recording sheet 100 as a recording medium is placed. The carriage 3 is configured to reciprocate in the scanning direction along the two guide rails 10 and 11 in a region facing the platen 2. An endless belt 14 is connected to the carriage 3, and the endless belt 14 is driven by a carriage drive motor 15, whereby the carriage 3 moves in the scanning direction.

  The inkjet head 4 is attached to the carriage 3 and moves in the scanning direction together with the carriage 3. The inkjet head 4 is connected to ink cartridges 17 of four colors (for example, black, yellow, cyan, and magenta) mounted on the printer 1 by a tube (not shown). A plurality of nozzles 34 are formed on the lower surface of the inkjet head 4 (the surface on the other side of the paper surface in FIG. 1). The ink jet head 4 ejects the four colors of ink supplied from the ink cartridge 17 to the recording paper 100 placed on the platen 2 from the plurality of nozzles 34.

  The transport mechanism 5 includes two transport rollers 18 and 19 disposed so as to sandwich the platen 2 in the transport direction orthogonal to the scanning direction. The transport mechanism 5 transports the recording paper 100 placed on the platen 2 in the transport direction by two transport rollers 18 and 19.

  The control device 6 includes a ROM (Read Only Memory), a RAM (Random Access Memory), an ASIC (Application Specific Integrated Circuit) including various control circuits, and the like. The control device 6 executes various processes such as printing on the recording paper 100 by the ASIC according to the program stored in the ROM. For example, in the printing process, the control device 6 controls the inkjet head 4, the carriage drive motor 15, and the like based on a print command input from an external device such as a PC to print an image or the like on the recording paper 100. . Specifically, an ink discharge operation for discharging ink while moving the inkjet head 4 in the scanning direction together with the carriage 3 and a transport operation for transporting the recording paper 100 in the transport direction by the transport rollers 18 and 19 alternately. To do.

(Inkjet head)
FIG. 2 is a plan view of the inkjet head 4. FIG. 3 is an enlarged view of a portion A in FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is a partially enlarged view of FIG. In FIGS. 4 to 6, the ink filled in the flow path unit 20 of the inkjet head 4 is indicated by the symbol “I”. The ink jet head 4 of this embodiment includes a flow path unit 20 and a piezoelectric actuator 21.

(Configuration of flow path unit)
As shown in FIGS. 4 and 5, the flow path unit 20 has a structure in which five plates 25 to 29 are stacked. The lowermost plate 29 among the five plates 25 to 29 is a nozzle plate in which a plurality of nozzles 34 are formed. On the other hand, the remaining four plates 25 to 28 on the upper side are formed with ink flow paths such as a manifold 36 and a pressure chamber 37 communicating with the plurality of nozzles 34.

  As shown in FIG. 3, four ink supply ports 35 are formed on the upper surface of the flow path unit 20 side by side in the scanning direction. Moreover, the flow path unit 20 has four manifolds 36 each extending in the transport direction. The four manifolds 36 are connected to the four ink supply ports 35.

  Furthermore, the flow path unit 20 has a plurality of nozzles 34 opened on the lower surface thereof and a plurality of pressure chambers 37 disposed on the upper surface thereof. As shown in FIG. 3, the plurality of nozzles 34 are arranged in the transport direction along the four manifolds 36 to form four nozzle rows. Similarly to the plurality of nozzles 34, the plurality of pressure chambers 37 are also arranged in the transport direction along the four manifolds 36, and constitute four rows of pressure chambers. Each pressure chamber 37 has a substantially elliptical planar shape that is long in the scanning direction. In the following description, the direction in which the plurality of nozzles 34 and the plurality of pressure chambers 37 are arranged parallel to the transport direction is also referred to as “nozzle arrangement direction”.

  As shown in FIG. 4, each pressure chamber 37 communicates with the manifold 36 at one end and communicates with the nozzle 34 at the other end. As shown by arrows in FIG. 4, a plurality of individual flow paths are formed in the flow path unit 20 so as to branch from the respective manifolds 36 and reach the nozzles 34 through the pressure chambers 37.

(Configuration of piezoelectric actuator)
As shown in FIGS. 3 to 6, the piezoelectric actuator 21 includes an ink sealing film 40, piezoelectric layers 44 and 45, a plurality of individual electrodes 42, and a common electrode 46.

  The ink sealing film 40 is bonded to the upper surface of the flow path unit 20 so as to cover the plurality of pressure chambers 37. The ink sealing film 40 is formed of a material having low ink permeability, for example, a metal material such as stainless steel.

  The two piezoelectric layers 44 and 45 are each made of a piezoelectric material. As the piezoelectric material constituting the piezoelectric layers 44 and 45, lead zirconate titanate which is a mixed crystal of lead titanate and lead zirconate can be employed. In addition, a lead-free piezoelectric material such as barium titanate or a niobium-based piezoelectric material may be employed. The piezoelectric layers 44 and 45 are bonded to the upper surface of the ink sealing film 40 while being stacked on each other. Each of the piezoelectric layers 44 and 45 has a rectangular planar shape in which the nozzle arrangement direction is the longitudinal direction.

  The plurality of individual electrodes 42 are arranged in the nozzle arrangement direction corresponding to the plurality of pressure chambers on the upper surface of the piezoelectric layer 44 that is the surface opposite to the piezoelectric layer 45. The individual electrode 42 has a substantially elliptical planar shape that is slightly smaller than the pressure chamber 37 and is long in the scanning direction, and is disposed to face the center of the corresponding pressure chamber 37. A connection terminal 42 a is provided at one end in the longitudinal direction of the individual electrode 42. The connection terminal 42 a extends in the scanning direction from the individual electrode 42 to a region not facing the pressure chamber 37 on the upper surface of the piezoelectric layer 44.

  The plurality of connection terminals 42a provided on the plurality of individual electrodes 42 are connected to a wiring member (not shown). A driver IC 53 is mounted on the wiring member. The driver IC 53 switches the potential of each individual electrode 42 between a predetermined drive potential and a ground potential based on the ejection control signal from the control device 6.

  The common electrode 46 is disposed almost entirely between the two piezoelectric layers 44 and 45. The common electrode 46 is disposed on the opposite side of the plurality of individual electrodes 42 with the upper piezoelectric layer 44 interposed therebetween, and is opposed to each of the plurality of individual electrodes 42. The common electrode 46 is electrically connected to a connection terminal (not shown) disposed on the upper surface of the piezoelectric layer 44. The common electrode 46 is connected to the ground wiring formed on the wiring member via the connection terminal, and is always maintained at the ground potential.

  In addition, the portion of the piezoelectric layer 44 sandwiched between the individual electrode 42 and the common electrode 46 shown in FIG. The active part 41 is polarized downward in the thickness direction, that is, in a direction from the individual electrode 42 toward the common electrode 46.

  As shown in FIGS. 3, 5, and 6, two grooves 51 and 52 are formed in the peripheral portion of each pressure chamber 37 of the upper piezoelectric layer 44. The two grooves 51 and 52 extend in the scanning direction in regions on both sides in the nozzle arrangement direction with respect to the pressure chamber 37 on the upper surface of the piezoelectric layer 44. 5 and 6, the two grooves 51 and 52 are formed only in the piezoelectric layer 44, but the grooves 51 and 52 may be deeply formed up to the lower piezoelectric layer 45. As described above, the grooves 51 and 52 are formed in both sides of each pressure chamber 37 of the piezoelectric layer 44, so that the deformation of the portion of the piezoelectric layer 44 facing the pressure chamber 37 is promoted. A pair of grooves 51 and 52 are provided for each pressure chamber 37 so as to sandwich the pressure chamber 37. Therefore, as shown in FIGS. 5 and 6, a portion 47 (a portion having a width of “W” in FIG. 6) between two pressure chambers 37 adjacent in the nozzle arrangement direction of the piezoelectric layer 44 is on the left side. A groove 51 close to the pressure chamber 37 (37A) and a groove 52 close to the right pressure chamber 37 (37B) are formed.

  The operation of the piezoelectric actuator 21 described above when ejecting ink from the nozzle 34 is as follows. It is assumed that the potential of a certain individual electrode 42 is switched from the ground potential to the driving potential by the driver IC 53. At this time, a potential difference is generated between the individual electrode 42 and the common electrode 46 held at the ground potential. Thereby, an electric field in the thickness direction is generated in the active portion 41 of the piezoelectric layer 44. Further, since the polarization direction of the active part 41 and the direction of the electric field coincide with each other, the active part 41 extends in the thickness direction, which is the polarization direction, and contracts in the plane direction. Along with the contraction deformation of the active portion 41, the two piezoelectric layers 44 and 45 are bent so as to protrude toward the pressure chamber 37 side. As a result, the volume of the pressure chamber 37 is reduced, pressure is applied to the ink inside the pressure chamber 37, and ink droplets are ejected from the ejection port 34 a of the nozzle 34 communicating with the pressure chamber 37.

  In addition, since the grooves 51 and 52 are formed around the pressure chambers 37 of the piezoelectric layer 44, the deformation of the portion of the piezoelectric layer 44 facing the pressure chambers 37 is promoted, and the volume of the pressure chambers 37 is increased. The amount of change increases. Therefore, the discharge speed of the ink discharged from the nozzle 34 can be increased.

  Incidentally, in the above-described ink jet head 4, it is originally preferable that the discharge speeds of the ink discharged from the nozzles 34 are uniform among the plurality of nozzles 34. Ink discharge speeds vary. An example is given below.

  If the individual electrode 42 is formed so as to be shifted in the surface direction of the piezoelectric layer 44 with respect to the normal position facing the central portion of the pressure chamber 37, the deformation of the piezoelectric layer 44 in the pressure chamber 37 is reduced accordingly. End up. As a result, the volume change amount of the pressure chamber 37 is also reduced, and the ink ejection speed from the nozzle 34 communicating with the pressure chamber 37 is reduced. In addition, when a plurality of individual electrodes 42 are formed on the piezoelectric layer 44, the position of a certain individual electrode 42 with respect to the pressure chamber 37 may be shifted and may differ from the position of other individual electrodes 42.

  For example, as will be described in detail later with reference to FIG. 8, when the green sheet 71 is fired to form the piezoelectric layer 44 after forming the individual electrodes 42 on the green sheet 71 before firing, Shrink in the surface direction from the original green sheet 71. Due to this influence, the position of each individual electrode 42 with respect to the corresponding pressure chamber 37 is shifted. In addition, since the contraction amount differs depending on where the individual electrodes 42 of the piezoelectric layer 44 are respectively formed, when the piezoelectric actuator 21 is joined to the flow path unit 20, the individual pressure chambers 37 are individually connected. The amount of displacement of the electrode 42 with respect to the pressure chamber 37 is also different.

  In addition, when the plurality of pressure chambers 37 are formed in the plate 25 by etching or the like, positions and shapes may be different among the plurality of pressure chambers 37 due to an error in manufacturing. Also due to this factor, the positional deviation amount of the individual electrode 42 with respect to the pressure chamber 37 differs among the plurality of pressure chambers 37.

  Therefore, in the present embodiment, the positions of the grooves 51 and 52 of the pressure chambers 37 are determined so that the variation in the ink ejection speed among the plurality of nozzles 34 is reduced. Specifically, as shown in FIG. 6, the position A of the grooves 51 and 52 corresponding to each pressure chamber 37 in the nozzle arrangement direction from the edge of the pressure chamber 37 is the pressure chamber 37 and the individual electrode 42. The position A of the grooves 51 and 52 is different between the plurality of pressure chambers 37, and is determined according to the positional deviation amount a in the nozzle arrangement direction. In FIG. 6, the grooves 51 and 52 on both sides of the left pressure chamber 37 </ b> A are formed at positions farther from the edge of the pressure chamber 37 than the grooves 51 and 52 on both sides of the right pressure chamber 37 </ b> B. Note that the value of the position A is the same in the groove 51 and the groove 52 corresponding to one pressure chamber 37. Accordingly, the two grooves 51 and 52 are provided at positions symmetrical with respect to the pressure chamber 37 in the nozzle arrangement direction.

  Each of the grooves 51 and 52 is a groove having a predetermined width in the nozzle arrangement direction. The above-mentioned “groove position A” refers to the edge of the pressure chamber 37 in the nozzle arrangement direction of the grooves 51 and 52. Says the position to the center. Further, the positional shift amount a refers to a shift amount in the nozzle arrangement direction between the center line C1 of the pressure chamber 37 and the center line C2 of the individual electrode 42. The positional deviation amount “a” is “a parameter related to the discharge speed of the liquid from the nozzle” in the present invention.

  FIG. 7 is a graph showing the relationship between the groove position A and the volume change amount of the pressure chamber 37. The “volume change amount of the pressure chamber 37” is a volume change amount of the pressure chamber 37 when a portion of the piezoelectric layer 44 covering the pressure chamber 37 is deformed, and is referred to as a displacement amount of the piezoelectric layer 44. You can also. As understood from FIG. 7, when the groove 51 (52) is located in the vicinity of the edge of the pressure chamber 37, the volume change amount of the pressure chamber 37 is the largest, and the position of the groove 51 (52) is the pressure. As the distance from the edge of the chamber 37 increases, the volume change amount of the pressure chamber 37 decreases. Therefore, in the present embodiment, the position A of the groove 51 (52) is set so that the variation in the volume change amount among the plurality of pressure chambers 37 is reduced.

  That is, for the pressure chamber 37 with a large positional deviation amount a with respect to the pressure chamber 37 of the individual electrode 42 and a small volume change amount, the value of the groove position A is set small, and the grooves 51, 52 is formed. On the other hand, for the pressure chamber 37 in which the positional displacement amount a of the individual electrode 42 is small and the volume change amount is relatively large, the value of the groove position A is set large, and the grooves 51, 52 is formed.

  Next, the manufacturing process of the inkjet head 4 will be described mainly focusing on the manufacturing process of the piezoelectric actuator 21. FIG. 8 is a diagram illustrating a manufacturing process of the inkjet head 4.

(Electrode formation process)
As shown in FIG. 8A, a plurality of individual electrodes 42 are formed on one surface of an unfired green sheet 71 to be the upper piezoelectric layer 44. Further, the common electrode 46 is formed on one surface of the unfired green sheet 72 to be the lower piezoelectric layer 45. The formation of the individual electrode 42 and the common electrode 46 can be performed by a known method such as screen printing, vapor deposition, or CVD.

(Lamination process, firing process)
Next, the two green sheets 71 and 72 are laminated so as to sandwich the common electrode 46. Thereafter, the two laminated green sheets 71 and 72 are baked at a predetermined temperature to obtain a laminated body of the piezoelectric layers 44 and 45. In the above description, the plurality of individual electrodes 42 are formed on the green sheet 71 that has not been fired. However, the plurality of individual electrodes 42 are formed after the piezoelectric layers 44 and 45 (green sheets 71 and 72) are fired. It is also possible to form it on the upper surface of 44 by screen printing or the like.

(Joining process)
Next, the piezoelectric actuator 21 is joined to the flow path unit 20. First, as shown in FIG. 8B, the ink sealing film 40 is bonded to the upper surface of the flow path unit 20 with an adhesive. The ink sealing film 40 does not necessarily have to be bonded at this stage, and may be simultaneously with the bonding of the plates 25 to 29 when the flow path unit 40 is manufactured. Further, the two piezoelectric layers 44 and 45 in which the individual electrode 42 and the common electrode 46 are formed on the upper surface of the ink sealing film 40 and formed in the steps of FIGS. After aligning with the unit 20, it is joined with an adhesive.

(Position displacement measurement process)
After the joining step, the positional deviation amount a with respect to the corresponding pressure chamber 37 is measured for each of the plurality of individual electrodes 42. The positional deviation amount a between the individual electrode 42 formed on the upper surface of the piezoelectric layer 44 and the pressure chamber 37 covered by the piezoelectric layers 44 and 45 can be measured, for example, as follows. First, a reference mark is provided in advance at a predetermined position on the upper surface of the flow path unit 20 that is not covered by the piezoelectric layers 44 and 45. Next, after joining the piezoelectric actuator 21 to the flow path unit 20 in the joining step, the position of each individual electrode 42 with respect to the reference mark of the flow path unit 20 is measured. Here, if the position of each pressure chamber 37 with respect to the reference mark of the flow path unit 20 does not change during the manufacturing process of the piezoelectric actuator 21 described above, the amount of positional deviation a of each individual electrode 42 with respect to the pressure chamber 37 is grasped. It will be possible.

  In addition, when forming the several pressure chamber 37 in the plate 25, when a position shifts between the several pressure chambers 37, it carries out as follows. When the plurality of pressure chambers 37 are formed on the plate 25 by etching, for example, the positional deviation has a certain tendency depending on the etching conditions such as a mask to be used. Information on this tendency is usually recorded in advance as assembly information from the viewpoint of traceability. Therefore, using this assembly information, it is possible to estimate the positional deviation amount a with respect to the pressure chamber 37 of each individual electrode 42. Further, if the positional displacement amount a between the pressure chamber and the individual electrode is individually measured for a plurality of pressure chambers using a sensor or the like, the positional displacement amount a can be obtained with high accuracy.

(Groove formation process)
Next, referring to the relationship between the groove position A and the volume change amount of the pressure chamber 37 shown in FIG. 7, the pressure chamber 37 corresponds to each pressure chamber 37 according to the positional deviation amount a of the individual electrode 42 with respect to each pressure chamber 37. The groove position A of the two grooves 51 and 52 is determined. This groove position A corresponds to the groove forming condition of the present invention. Based on the groove position A thus determined, two grooves 51 and 52 are formed in the piezoelectric layer 44 for each pressure chamber 37 as shown in FIG. The grooves 51 and 52 can be formed with high accuracy by employing, for example, laser processing using a picosecond laser or the like.

  As described above, in the present embodiment, the positions A of the plurality of grooves 51 (52) respectively formed in the peripheral portions of the plurality of pressure chambers 37 are parameters related to the discharge speed from the nozzle 34. The position A is determined in accordance with the positional shift amount a of the electrode 42 with respect to the pressure chamber 37, and the position A is different among the plurality of grooves 51 (52). As a result, even if there are variations in the ink ejection speed among the plurality of nozzles 34, the ejection speed is corrected by changing the position or shape of the groove 51 (52). The variation in the ink ejection speed between the two is reduced.

  In the embodiment described above, the inkjet head 4 corresponds to the liquid ejection apparatus of the present invention. The flow path unit 20 corresponds to the flow path structure of the present invention.

  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.

1] In the above embodiment, the positions of the plurality of grooves 51 (52) are made different according to the positional deviation amount a of the individual electrode 42 with respect to the pressure chamber 37, which is a parameter related to the discharge speed from the nozzle 34. . On the other hand, the shape of the plurality of grooves 51 (52) may be different. For example, as the length of the groove 51 (52) is longer, the deformation of the piezoelectric layer 44 is increased, and the volume change amount of the pressure chamber 37 is increased. Therefore, as shown in FIG. 9, the groove length B of the groove 51 (52) is different between the plurality of pressure chambers 37 in order to suppress the variation in the ink ejection speed among the plurality of nozzles 34. It may be allowed.

  Further, the greater the width of the groove 51 (52) or the deeper the groove 51 (52), the greater the deformation of the piezoelectric layer 44 and the greater the volume change amount of the pressure chamber 37. Therefore, as shown in FIGS. 10 and 11, the groove width C or the groove depth D of the groove 51 (52) may be different among the plurality of pressure chambers 37. When the groove 51 (52) is formed by laser processing, the groove width C or the groove depth D can be easily changed by changing the irradiation energy or irradiation time of the laser beam.

  Furthermore, two or more groove forming conditions among the groove position A, the groove length B, the groove width C, and the groove depth D described above may be made different among the plurality of pressure chambers 37. .

2] As a parameter related to the ink ejection speed from the nozzle 34 for determining the position or shape of the groove, in addition to the positional deviation amount a of the individual electrode 42 exemplified in the above embodiment, There is something like this. These parameters can be used alone or in combination.

(A) Capacitance between a plurality of active portions 41 sandwiched between a plurality of individual electrodes 42 and a common electrode due to factors such as variations in thickness of the piezoelectric layer 44 or variations in size of the individual electrodes 42. May vary. The higher the capacitance of the active portion 41, the greater the deformation of the piezoelectric layer 44 in the pressure chamber 37, the greater the volume change amount of the pressure chamber 37, and the higher the ink ejection speed. Therefore, the capacitances of the plurality of active portions 41 are measured in the manufacturing stage of the piezoelectric actuator 21, and the corresponding grooves 51 (52) are respectively corresponding to the capacitance values of the plurality of active portions 41. The position or shape may be different.

(B) Due to factors such as variations in the thickness of the piezoelectric layers 44 and 45, the natural frequency may vary between portions of the piezoelectric layers 44 and 45 that cover the plurality of pressure chambers 37.

  The high natural frequency means that the rigidity of the portion of the piezoelectric layers 44 and 45 covering the pressure chamber 37 is high. When the piezoelectric layers 44 and 45 are deformed, the piezoelectric layers 44 and 45 receive pressure from the ink in the pressure chamber 37. At this time, if the rigidity of the piezoelectric layers 44 and 45 is high (the natural frequency is high), the piezoelectric layers 44 and 45 can be deformed without losing the pressure of the ink. That is, the higher the natural frequency of the piezoelectric layers 44 and 45, the greater the deformation of the piezoelectric layers 44 and 45, and thus the higher the ink ejection speed. Therefore, the positions or shapes of the corresponding grooves 51 (52) may be varied according to the natural frequency of the piezoelectric layer 44 covering the plurality of pressure chambers 37.

(C) Due to manufacturing errors when forming the plurality of nozzles 34 on the nozzle plate 29, the diameter of the discharge ports 34 a may vary between the plurality of nozzles 34. The smaller the diameter of the ejection port 34a of the nozzle 34, the greater the ejection speed of ink ejected from the nozzle 34. Therefore, the positions or shapes of the corresponding grooves 51 (52) may be varied according to the diameters of the discharge ports 34a of the plurality of nozzles 34, respectively.

(D) When the types of ink discharged from the nozzles 34 are different, the lower the ink viscosity, the higher the ink discharge speed. Therefore, for each of the plurality of nozzles 34, the positions or shapes of the plurality of grooves 51 (52) respectively corresponding to the plurality of nozzles 34 may be varied according to the viscosity of the ink to be ejected.

3] In the above embodiment, as shown in FIG. 8C, after the piezoelectric actuator 21 is joined to the flow path unit, the grooves 51 and 52 are formed in the piezoelectric layer 44. On the other hand, if the parameters related to the ink ejection speed are already known before the joining step, the grooves 51 and 52 may be formed in the piezoelectric layer 44 before joining. For example, parameters such as the diameter of the ejection port 34a of the nozzle 34 and the type of ink ejected from the nozzle 34 can be grasped before the joining process.

4] In the above embodiment, as shown in FIGS. 5 and 6, two grooves 51 and 52 are formed in the portion 47 between two adjacent pressure chambers 37 of the piezoelectric layer 44. On the other hand, as shown in FIG. 12, only one groove 61 may be formed in the portion 47 between the two pressure chambers 37 of the piezoelectric layer 44. In this embodiment, the deformation of the piezoelectric layer 44 in the two pressure chambers 37 on both sides thereof is promoted by the single groove 61 existing between the two pressure chambers 37.

  In the embodiment, the groove 51 (52) is formed in the piezoelectric layer 44 at a position adjacent to the pressure chamber 37 in the nozzle arrangement direction (longitudinal direction of the pressure chamber 37). On the other hand, a groove may be formed at a position adjacent to the scanning direction (short direction of the pressure chamber 37). Furthermore, a groove may be formed over the entire circumference so as to surround one pressure chamber 37.

5] When one groove is provided in close proximity to each of the two pressure chambers 37, the groove is a volume change amount of both of the two pressure chambers 37 on both sides thereof, and thus each of the two nozzles 34 Affects ink ejection speed. Therefore, in such a case, the parameter (for example, the positional deviation amount a of the individual electrode 42 with respect to the pressure chamber 37) of the nozzle 34 communicating with one of the two pressure chambers 37 adjacent to the groove. On the other hand, if the position or shape of the groove is determined based on this, the influence of the groove on the nozzle 34 communicating with the other pressure chamber 37 is not taken into consideration. It can be. Therefore, in the above case, the positions or shapes of the plurality of grooves differ depending on the parameters related to the discharge speed for each of the two nozzles 34 communicating with the two pressure chambers 37 adjacent to each groove. It is preferable.

  For example, as shown in FIG. 12, if there is one groove 61 between two pressure chambers 37, parameters related to the discharge speed of two nozzles 34 communicating with the two pressure chambers 37 (for example, The average value of the positional deviation amount a of the individual electrode 42) is obtained, and the position or shape of the groove 61 is determined according to this average value.

  On the other hand, when two grooves 51 and 52 exist between the two pressure chambers 37 as shown in FIG. 6, the groove 51 (52) adjacent to the one pressure chamber 37 is compared with the configuration of FIG. 12. It can be said that the influence on the other pressure chamber 37 on the opposite side is small. However, when the width W in the nozzle arrangement direction of the portion 47 between the pressure chambers 37 of the piezoelectric layer 44 is small, the influence of the groove 51 (52) on the other pressure chamber 37 cannot be ignored. Therefore, determination of the position or shape of the grooves 51 and 52 in the form of FIG. 6 is performed as follows.

  When the width W of the portion 47 between the pressure chambers 37 of the piezoelectric layer 44 is equal to or greater than the predetermined width W0 and the width of the portion 47 is sufficiently large, the position or shape of each of the grooves 51 and 52 is set to a pressure close to each other. It is determined only by the parameters of the nozzle 34 communicating with the chamber 37. On the other hand, when the width W of the portion 47 between the pressure chambers 37 of the piezoelectric layer 44 is smaller than the predetermined width W0 and the width of the portion 47 is small, the positions or shapes of the grooves 51 and 52 are set to the two pressure chambers 37. Is determined in accordance with the parameters for each of the two nozzles 34 communicating with each other. Of the two pressure chambers 37, the groove 51 (52) has a greater influence on the pressure chamber 37 in which the groove 51 (52) is closer. Therefore, when determining the position or shape of the groove 51 (52), a large weighting factor is applied to the parameter of the nozzle 34 communicating with the adjacent pressure chamber 37, and the parameter of the nozzle 34 communicating with the pressure chamber 37 on the opposite side is determined. It is desirable to apply a weight according to the magnitude of the influence, such as applying a small weighting coefficient to. Further, the predetermined width W0 of the portion 47 of the piezoelectric layer 44 can be, for example, 25% of the separation distance (center-to-center distance) between the two adjacent pressure chambers 37 in the nozzle arrangement direction.

6] All of the plurality of grooves respectively provided around the plurality of pressure chambers 37 (the plurality of nozzles 34) are determined according to the parameters related to the discharge speed of the corresponding nozzle 34, and all the grooves The positions or shapes of the need not be different. For example, the plurality of nozzles 34 can be divided into a plurality of groups by grouping the nozzles 34 having similar discharge speeds, and the position or shape of the groove can be determined for each group. That is, the position and shape of the groove are all the same among the nozzles 34 belonging to one group, and the position or shape of the groove is different between the nozzles 34 belonging to different groups.

7] The configuration of the flow path unit and the piezoelectric actuator is not limited to that of the above embodiment. For example, the number of piezoelectric layers of the piezoelectric actuator is not limited to two and can be changed as appropriate. Further, the shape of the pressure chamber 37 and the corresponding individual electrode 42 is not limited to the shape of the above embodiment. For example, in the above-described embodiment, the individual electrode 42 is disposed on the side opposite to the pressure chamber 37 of the piezoelectric layer 44, but may be disposed on the pressure chamber 37 side.

8] In the embodiment, for the purpose of reducing variation in ejection speed from the plurality of nozzles 34 in one inkjet head 4, the groove forming conditions of each groove of the piezoelectric actuator 21 are set to the corresponding nozzles 34. Is determined based on a parameter related to the ink ejection speed. On the other hand, the present invention can also be applied in order to reduce the difference in ejection speed between the plurality of inkjet heads 4. That is, when manufacturing a plurality of inkjet heads 4, the groove forming conditions of each inkjet head 4 are determined based on parameters related to the ejection speed of the inkjet head 4. That is, by adjusting the groove forming conditions of each inkjet head 4, it is possible to reduce variations in the ink ejection speed from the nozzles 34 among the plurality of inkjet heads 4.

9] The inkjet head may be configured by combining a plurality of head units each having a plurality of nozzles. An inkjet printer 71 shown in FIG. 13 includes a line-type inkjet head 74 that is long in the width direction of the recording paper 100. The ink jet head 74 has six head units 80 arranged along the paper width direction. The six head units 80 are attached to a plate-like head holder 81. The head holder 81 is supported in a horizontal posture by two left and right support members 82. Four colors of ink are supplied to the inkjet head 74 from an ink cartridge 73 mounted on the holder 75. The ink jet head 74 records an image on the recording paper 100 by ejecting ink from the nozzles 84 of the six head units 80 onto the recording paper 100 conveyed by the conveying rollers 78 and 79.

  Each head unit 80 includes a flow path unit 85 and a piezoelectric actuator 86. The flow path unit 85 and the piezoelectric actuator 86 have the same configuration as that of the ink jet head of the embodiment shown in FIG. The flow path unit 85 includes a plurality of nozzles 84 arranged in four rows on the lower surface thereof, and a plurality of pressure chambers (not shown) that respectively communicate with the plurality of nozzles 84. Although not shown in detail, the piezoelectric actuator 86 includes a piezoelectric layer and a plurality of individual electrodes respectively corresponding to the plurality of pressure chambers of the flow path unit 85. Similarly to the above-described embodiment, a plurality of grooves are formed in the piezoelectric layer around the plurality of pressure chambers.

  In this inkjet head 74, the groove of the piezoelectric actuator 86 between the six head units 80 is a parameter related to the ejection speed of ink from the nozzle 84 (for example, the positional deviation amount shown in FIG. 6 of the above embodiment). The position or shape varies depending on a) and the like. As a result, even when there is a variation in the discharge speed of the ink from the nozzles 84 among the six head units 80, the discharge speed is corrected by making the positions or shapes of the grooves different among the six head units 80. Therefore, it is possible to reduce the variation in the discharge speed among the six head units 80. In the above embodiment, the head unit 80 corresponds to the liquid discharge unit of the present invention.

  The embodiments described above and modifications thereof apply the present invention to an ink jet head that prints an image or the like by ejecting ink onto a recording sheet, but is used for various purposes other than printing an image or the like. The present invention can also be applied to a liquid ejecting apparatus. For example, the present invention can also be applied to a liquid ejection device that ejects a conductive liquid onto a substrate to form a conductive pattern on the substrate surface.

4 Inkjet Head 20 Channel Unit 21 Piezoelectric Actuator 34 Nozzle 34a Discharge Port 37 Pressure Chamber 41 Active Part 42 Individual Electrode 44, 45 Piezoelectric Layer 46 Common Electrode 51, 52 Groove 61 Groove 74 Inkjet Head 80 Head Unit 84 Nozzle 85 Channel Unit 86 Piezoelectric actuator

Claims (11)

A flow path structure including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, each having a liquid flow path, and a piezoelectric actuator provided in the flow path structure,
The piezoelectric actuator is
A piezoelectric layer arranged to cover the plurality of pressure chambers;
A plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers;
A common electrode disposed on the opposite side of the plurality of individual electrodes across the piezoelectric layer, and facing the plurality of individual electrodes;
A plurality of grooves each formed in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer,
At least two or more grooves included in the plurality of grooves have different positions or shapes according to parameters related to the discharge speed of the liquid from the corresponding nozzles.   The position or shape of each of the at least two or more grooves differs depending on the parameter for each of the two nozzles communicating with the two pressure chambers adjacent to the groove. Item 2. The liquid ejection device according to Item 1.   The liquid ejecting apparatus according to claim 1, wherein the at least two or more grooves have different positions according to the parameter.   The liquid ejecting apparatus according to claim 1, wherein the at least two or more grooves have different lengths according to the parameter.   The liquid ejection apparatus according to claim 1, wherein the at least two or more grooves have different depths according to the parameter.   The liquid ejection apparatus according to claim 1, wherein the parameter includes a positional deviation amount between the pressure chamber and the individual electrode in a surface direction of the piezoelectric layer.   7. The parameter according to claim 1, wherein the parameter includes a capacitance of an active portion that is a portion of the piezoelectric layer sandwiched between the individual electrode and the common electrode. Liquid discharge device.   The liquid ejection apparatus according to claim 1, wherein the parameter includes a diameter of an ejection port of the nozzle.   The liquid ejection apparatus according to claim 1, wherein the parameter includes a viscosity of the liquid ejected from the nozzle. Having a plurality of liquid discharge units;
Each liquid discharge unit includes a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, each having a liquid channel formed therein, and a piezoelectric actuator provided in the channel structure. With
The piezoelectric actuator is
A piezoelectric layer arranged to cover the plurality of pressure chambers;
A plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers;
A common electrode disposed on the opposite side of the plurality of individual electrodes across the piezoelectric layer, and facing the plurality of individual electrodes;
A plurality of grooves each formed in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer,
The liquid ejecting apparatus according to claim 1, wherein the position or shape of the groove of the piezoelectric actuator differs between the plurality of liquid ejecting units in accordance with a parameter related to a liquid ejecting speed from the nozzle. A flow path structure including a plurality of nozzles and a plurality of pressure chambers communicating with the plurality of nozzles, each having a liquid flow path, and a piezoelectric actuator provided in the flow path structure;
The piezoelectric actuator includes a piezoelectric layer disposed in the flow path structure so as to cover the plurality of pressure chambers, and a plurality of individual electrodes provided on the piezoelectric layer so as to face the plurality of pressure chambers, respectively. And a common electrode that is disposed on the opposite side of the plurality of individual electrodes across the piezoelectric layer and that faces the plurality of individual electrodes, and is formed in a portion of the piezoelectric layer that surrounds the plurality of pressure chambers, respectively. A plurality of grooves, and a method for manufacturing a liquid ejection device,
Forming a plurality of grooves in a peripheral portion of the plurality of pressure chambers of the piezoelectric layer, respectively,
In the groove forming step,
Based on a parameter related to the discharge speed of the liquid for each nozzle, a groove forming condition related to the position or shape of the groove corresponding to the pressure chamber communicating with the nozzle is determined,
A method of manufacturing a liquid ejection apparatus, wherein the groove is formed based on the determined groove forming condition.

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