JP2009083262A - Liquid transferring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid transferring apparatus which is less influenced by a deformation characteristic due to an error at the time of manufacture and prevents manufacturing costs from inflating needlessly. <P>SOLUTION: A piezoelectric actuator 3 includes both a diaphragm 30 secured to a predetermined surface of a channel unit 2 to block pressure chambers 14 formed in the channel unit 2, and a piezoelectric layer 31 stacked on the diaphragm 30. The diaphragm 30 is equipped with recesses 36 on the opposite side to the channel unit 2. The recess 36 is formed with a width which occupies from a position corresponding to the inside of the pressure chamber 14 to a position corresponding to the outside of the pressure chamber 14 in a region not overlapped with a first electrode 32 in a plane view. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid transfer apparatus.

  Currently, liquid transfer devices that apply pressure to a liquid and transfer it to a predetermined position are widely used, and an ink jet head that is one form thereof is known.

  The ink jet head includes a flow path unit having a pressure chamber communicating with a nozzle, and a piezoelectric actuator that applies pressure to ink in the pressure chamber. The ink can be ejected from the nozzles by applying pressure to the ink in the pressure chamber.

  There are various types of piezoelectric actuators used in such an ink jet head, and among them, unimorph type piezoelectric actuators are known as those having good deformation efficiency.

  The piezoelectric actuator includes a diaphragm covering the pressure chamber, a piezoelectric layer formed of lead zirconate titanate (PZT) laminated on the diaphragm, a common electrode extending in the surface direction of the piezoelectric layer, In the stacking direction, the common electrode and the piezoelectric layer are disposed so as to sandwich the individual electrode disposed at a position corresponding to the size of the pressure chamber.

  Then, by applying a drive voltage to the individual electrode, the piezoelectric layer overlapping the individual electrode in a plan view is deformed so as to contract in the plane direction. At this time, due to the contraction of the piezoelectric layer, the diaphragm on which the piezoelectric layer is laminated is deformed so as to be convex toward the pressure chamber side with the center as an apex. As a result, the volume in the pressure chamber decreases, a pressure wave is generated in the pressure chamber, the pressure wave is applied to the liquid in the pressure chamber, and ink is ejected from the nozzle.

  In recent years, such inkjet heads tend to have a plurality of nozzles arranged densely and densely for the purpose of downsizing and high-quality recording images, and the pressure chambers connected to these nozzles are also high. It is becoming denser.

  As a result, when a driving voltage is applied to an individual electrode arranged in a certain pressure chamber and the piezoelectric layer and the diaphragm are deformed, this deformation is applied to the piezoelectric layer and the diaphragm in a region facing the adjacent pressure chamber. The phenomenon (so-called crosstalk) that causes the ink ejection characteristics of nozzles that propagate to the adjacent pressure chambers to become unstable cannot be ignored.

  Therefore, as a countermeasure, in Patent Document 1, the diaphragm 30 in which a groove 36 is formed so as to overlap with a region along the edge of the pressure chamber 14 in a region that does not overlap with the pressure chamber 14 in a plan view. An ink jet head having the above is disclosed.

The vibration plate 30 of the inkjet head is thinner in the region where the groove 36 is formed than in other regions. For this reason, in the area | region in which the groove | channel 36 was formed, rigidity can be made small compared with another area | region. Accordingly, such a region is easily deformed, so that the diaphragm 30 is easily deformed as compared with the case where the groove 36 is not formed. Accordingly, it is possible to suppress power consumption that is consumed when the volume of the pressure chamber 14 is changed as compared with a case where the groove 36 is not formed in the diaphragm 30. Further, in the vibration plate 30 in which the groove 36 is formed, the deformation of the vibration plate 30 and the piezoelectric layer 31 is difficult to propagate in the groove 36 portion, so that crosstalk in which the deformation propagates to the adjacent pressure chamber 14 is prevented. can do.
JP 2006-93034 A

  In manufacturing the ink jet head described in Patent Document 1, when the groove 36 is formed in the vibration plate 30 made of a metal material such as stainless steel, a known processing method such as etching or pressing may be used. it can.

  However, when the groove 36 is formed by such a processing method, an error may occur with respect to a desired size and position set at the time of design. If an error occurs, the rigidity (ease of deformation) of the diaphragm 30 also changes with respect to a desired size at the time of design. For this reason, in order to make the piezoelectric actuator have the desired deformation characteristics at the time of designing, the force applied to the diaphragm 30 by the piezoelectric layer must be adjusted so as to compensate for the change in rigidity of the diaphragm 30.

  Here, as a method of adjusting the force applied to the vibration plate 30, a method of adjusting the magnitude of the drive voltage applied to the individual electrode 32, or a deformation characteristic of the piezoelectric layer 31 by changing the physical properties of the piezoelectric layer 31. However, in order to carry out these methods, the specifications must be different from those at the beginning of the design, resulting in a high cost.

  The present invention has been made to solve this problem, and it is an object of the present invention to provide a liquid transfer apparatus that is less affected by deformation characteristics due to errors during manufacturing and does not unnecessarily increase manufacturing costs.

  According to a first aspect of the present invention, there is provided the liquid transfer device, wherein the liquid inlet and the pressure chamber communicating with the liquid outlet are formed to open on a predetermined surface, and the pressure is applied to one surface of the flow path unit. A piezoelectric actuator provided to cover the chamber, wherein the piezoelectric actuator includes a diaphragm fixed to the predetermined surface of the flow path unit so as to close the opening of the pressure chamber; A piezoelectric layer laminated on the diaphragm; a first electrode formed in a region overlapping with the pressure chamber in plan view on one surface side of the piezoelectric layer; and on the other surface side of the piezoelectric layer. A second electrode formed in a region facing at least the first electrode, and the diaphragm is unimorph-deformed by contraction of the piezoelectric material layer, the diaphragm being the flow path unit A concave portion is provided on the opposite surface, and the concave portion corresponds to the outside of the pressure chamber from a position corresponding to the inside of the pressure chamber in a region not overlapping with the first electrode in plan view. It is formed with the width which occupies to a position.

  According to a second aspect of the present invention, in the first aspect, the concave portion extends so as to surround the pressure chamber in a plan view.

  According to a third aspect of the present invention, in the first or second aspect, the concave portion has a first portion that overlaps the pressure chamber in a plan view and a second portion that overlaps the outside of the pressure chamber. And a portion.

  According to these inventions, the diaphragm is easily deformed by forming the concave portion in the diaphragm. For this reason, when the piezoelectric layer is contracted and deformed, the amount of deformation of the diaphragm that protrudes toward the pressure chamber becomes larger than that when no recess is formed. In addition, the deformation characteristics of the unimorph-deformed piezoelectric actuator are affected by two factors, namely, the ease of contraction of the piezoelectric layer and the ease of bending of the diaphragm with respect to the flow path unit. In the region that does not overlap with the first electrode, a width that occupies from a position corresponding to the inside of the pressure chamber to a position corresponding to the outside of the pressure chamber is formed, so that the displacement of the concave portion during manufacturing can be prevented. Even if it occurs, the change in the two previous factors is reduced, so that variation in the deformation characteristics of the piezoelectric actuator due to manufacturing errors can be suppressed.

  In the present invention, “plan view” is synonymous with viewing from a direction orthogonal to “a predetermined surface of the flow path unit” and “a surface fixed to the flow path unit of the diaphragm”.

  In a liquid transfer device according to a fourth aspect of the present invention, in any one of the first to third aspects, the flow path unit includes a plurality of the pressure chambers, and the plurality of pressure chambers are arranged in a predetermined direction. The diaphragm is provided with a plurality of the concave portions overlapping each of the plurality of pressure chambers in a plan view, and is disposed between two pressure chambers arranged adjacent to each other in the predetermined direction. Is characterized in that a concave portion belonging to one pressure chamber and a concave portion belonging to the other pressure chamber are formed, and these two concave portions are not connected to each other and are partitioned by a hill portion where no concave portion is formed. And

  According to the present invention, in order to join the diaphragm and the flow path unit, when the diaphragm is pressed from the surface opposite to the flow path unit with the jig, a sufficient pressing force is secured to ensure the joining. be able to. In other words, since the two concave portions do not contact the jig, it is not possible to press this portion, but the hill formed between the two concave portions can be pressed by the jig, so that the pressing force is ensured. It can be done.

  In the liquid transfer device according to a fifth aspect, in the fourth aspect, the hill portion is formed with an auxiliary recess that extends in a direction orthogonal to the predetermined direction without being connected to the two recesses. It is characterized by that.

  According to the present invention, a total of three recesses, that is, two recesses and an auxiliary recess, exist between two adjacent pressure chambers. Therefore, it is possible to further improve the effect of preventing the crosstalk that propagates to the portion corresponding to the other pressure chamber by the deformation of the diaphragm corresponding to one of the two pressure chambers.

  According to a sixth aspect of the present invention, in the first to fifth inventions, the first electrode and the second electrode are for applying an electric field parallel to the thickness direction to the piezoelectric layer. The piezoelectric layer is polarized in the thickness direction.

  The present invention can provide a droplet transfer device that is less affected by deformation characteristics due to errors during manufacturing and that has reduced manufacturing costs.

  A first embodiment of the present invention will be described. This embodiment is an example in which the present invention is applied to an inkjet head that ejects ink onto a recording sheet as a liquid transfer device.

  First, an ink jet printer 100 including the ink jet head 1 will be described with reference to FIG.

  An ink jet printer 100 shown in FIG. 1 includes a carriage 101 that can reciprocate in the scanning direction of an arrow shown in the figure, and a nozzle 20 (mounted on the carriage 101) that faces the recording paper P ( 2), an inkjet head 1 that ejects ink droplets, and a conveyance roller 102 that conveys the recording paper P in the paper feeding direction indicated by an arrow in the figure.

  The ink jet printer 100 ejects ink droplets from the nozzle 20 toward the recording paper P while reciprocating the ink jet head 1 in the scanning direction when recording. Then, the recording paper P recorded by the inkjet head 1 is discharged in the paper feeding direction by the transport roller 102.

  Next, the inkjet head 1 will be described with reference to FIGS.

  First, as shown in FIG. 2, the inkjet head 1 includes a flow path unit 2 having pressure chambers 14 and the like that are respectively communicated with a plurality of nozzles 20 arranged side by side in the paper feed direction, and the flow path unit 2. A piezoelectric actuator 3 stacked on the upper surface of the piezoelectric actuator 3.

  As shown in FIG. 2, in the flow path unit 2, a plurality of nozzles 20 are arranged side by side in the paper feed direction, and the pressure chambers 14 respectively communicating with the plurality of nozzles 20 are the same as the plurality of nozzles 20. Arranged side by side in the paper feed direction. Further, the manifold 17 communicating with the pressure chambers 14 is disposed so as to extend in the paper feeding direction, and includes an ink supply port 18 formed between the manifold 17 and an ink tank (not shown). The piezoelectric actuator 3 includes a plurality of individual electrodes 32 (first electrodes) that overlap the pressure chambers 14 when viewed from a direction orthogonal to the surface joined to the flow path unit 2 (plan view). Recesses 37 are formed so as to surround 32. The individual electrode 32 is provided with a terminal portion 35 at the other end opposite to the one end overlapping the nozzle 20 in plan view. A driver IC (not shown) is connected to the terminal portion 35 via a flexible wiring member such as a flexible printed wiring board. The driver IC is connected to each individual electrode 32 via the terminal portion 35. In contrast, a drive voltage is selectively supplied.

  Next, the inkjet head 1 described with reference to FIG. 2 will be described with reference to FIG.

  The inkjet head 1 includes a pressure chamber 14 having one end connected to the communication holes 16 and 19 communicating with the nozzle 20 in plan view and the other end communicating to the communication hole 15 communicating with the manifold 17. The concave portion 37 includes a portion that overlaps the inside of the pressure chamber 14 in a plan view and a portion that overlaps the outside from the peripheral portion of the pressure chamber 14. Furthermore, the individual electrode 32 is disposed in a portion overlapping the inside of the pressure chamber 14 so as not to overlap the concave portion 37.

  Here, the concave portion 37 has the same shape as the concave portion 36 formed in the diaphragm 30 (described later) which is a part of the piezoelectric actuator 3 in plan view. Therefore, the recess 36 has a portion extending from a portion overlapping the inside of the pressure chamber 14 to a portion overlapping the outside of the pressure chamber 14 in plan view. The length in the direction orthogonal to the extending direction of the recess 36 is defined as the width of the recess 36.

  The ink jet head 1 will be described with reference to FIG. 4 which is a cross section of the ink jet head 1 taken along the line I-I shown in FIG.

  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, a manifold plate 12, and a nozzle plate 13, and these four plates 10 to 13 are laminated and bonded. Among these, the cavity plate 10, the base plate 11 and the manifold plate 12 are stainless steel plates, and ink flow paths such as a manifold 17 and a pressure chamber 14 described later can be easily etched in these three plates 10-12. It can be formed. The nozzle plate 13 is formed of, for example, a polymer synthetic resin material such as polyimide, and is bonded to the lower surface of the manifold plate 12. Or this nozzle plate 13 may be formed with metal materials, such as stainless steel, similarly to the three plates 10-12.

  Next, these four plates 10 to 13 will be described. As shown in FIG. 4, the nozzle 20 is formed in the nozzle plate 13 arrange | positioned at the lowest layer in the lamination direction. The nozzle 20 is formed by performing excimer laser processing on a substrate of a polymer synthetic resin such as polyimide. The nozzle 20 communicates with a communication hole 19 formed in the manifold plate 12 joined to the nozzle plate 13. The manifold plate 12 is formed with the manifold 17 described above. Further, in the stacking direction, the base plate 11 joined to the manifold plate 12 has a communication hole 15 communicating with the manifold 17 and a communication hole 16 communicating with the communication hole 19. The cavity plate 10 joined to the base plate 11 has a pressure chamber 14 having one end communicating with the communication hole 15 and the other end communicating with the communication hole 16. Further, the piezoelectric actuator 3 is bonded to the cavity plate 10 on the surface opposite to the surface bonded to the base plate 11.

  Next, the piezoelectric actuator 3 will be described. As shown in FIG. 4, the piezoelectric actuator 3 has a vibration plate 30 joined to the cavity plate 10 and an insulating layer 33 laminated on the upper surface of the vibration plate 30, and is further laminated on the insulating layer 33. Common electrode 34 (second electrode), the piezoelectric layer 31 laminated on the common electrode 34 and the insulating layer 33, and the piezoelectric layer 31 disposed on the upper surface of the piezoelectric layer 31 so as to sandwich the common electrode 34. And an individual electrode 32. Here, the diaphragm 30 and the cavity plate 10 are joined using a thermosetting resin or the like. An insulating layer 33 is formed on the surface of the diaphragm 30 opposite to the pressure chamber 14. The insulating layer 33 is formed by depositing a ceramic material such as alumina or zirconia on the surface of the diaphragm 30 by a chemical vapor deposition (CVD) method, an aerosol deposition method (AD method), or a sputtering method. It is formed by. In addition, a common electrode 34 is disposed on the insulating layer 33 at a portion overlapping the pressure chamber 14 in plan view. A piezoelectric layer 31 is formed on the surfaces of the common electrode 34 and the insulating layer 33. The piezoelectric layer 31 is formed by depositing particles of piezoelectric material on the surfaces of the insulating film 33 and the common electrode 34 by a CVD method, an AD method, or the like. The piezoelectric layer 31 is polarized in the stacking direction indicated by the arrow in FIG. Here, when the piezoelectric layer 31 is driven, an electric field is applied in the stacking direction by the individual electrode 32 and the common electrode 34. As a result, the piezoelectric layer 31 contracts and deforms in a direction along the plane of the diaphragm 30. By this contraction deformation, the diaphragm 30 is bent toward the pressure chamber 14 to be convexly deformed, and unimorph deformation is performed to deform the volume of the pressure chamber 14.

  Further, a description will be given with reference to FIG. 5 which is a cross section taken along the line II-II of the inkjet head 1 shown in FIG.

  Here, in FIG. 5, a portion that partitions the plurality of pressure chambers 14 arranged in the paper feeding direction is referred to as a partition wall 10a. First, the diaphragm 30 to be joined to the cavity plate 10 has a recess 36 formed on the side opposite to the surface to be joined to the cavity plate 10. A concave portion 37 is formed in the piezoelectric layer 31 that is laminated with the diaphragm 30 and the insulating layer 33 interposed therebetween. Moreover, the recessed parts 36 and 37 are each arrange | positioned in each pressure chamber 14 as shown in FIG. 3, and the adjacent recessed parts 36 and 37 are arrange | positioned apart. Therefore, the diaphragm 30 has a hill portion 38 having the same thickness as a portion where the concave portions 36 and 37 are not formed in a cross-sectional view taken along the line II-II in FIG. 5 (hereinafter referred to as “cross-sectional view”). Thus, when the hill portion 38 exists, when the diaphragm 30 is pressed toward the cavity plate 10 when the diaphragm 30 and the cavity plate 10 are joined, in addition to the portion where the recess 36 is not formed. It is possible to apply a pressing force by applying a jig for joining to the hill 38. Accordingly, a pressing force can be applied to the joining surface to be joined to the partition wall 10a, so that the diaphragm 30 and the partition wall 10a can be reliably joined.

  Next, the recess 36 formed in the vibration plate 30 and the recess 37 formed in the piezoelectric layer 31 will be described with reference to FIG.

  FIG. 6 is an enlarged cross-sectional view of the vicinity of the partition wall 10 a belonging to the cavity plate 10. As shown in FIG. 6, when the distance 39 between the center line of the recess 36 and the center line of the partition wall 10a is separated by a predetermined size in a sectional view, the recess 36 overlaps the pressure chamber 14 in a plan view. A portion 40 (first portion) and a portion 41 (second portion) overlapping the partition wall 10a are provided. And when the magnitude | size of the recessed part 36 is constant, the area of the parts 40 and 41 changes by planar view by the position where the recessed part 36 is arrange | positioned. For example, when the center position of the recess 36 is separated from the center position of the partition wall 10a (distance 39 increases), the portion 40 becomes larger, but the portion 41 becomes smaller. In addition, when the center position of the recess 36 approaches the center position of the partition wall 10a (distance 39 decreases), the portion 40 becomes smaller but the portion 41 becomes larger.

  As described above, as a factor for determining the sizes of the portions 40 and 41 of the recess 36, the arrangement is determined when the recess 36 is formed in the diaphragm 30. And after forming the recessed part 36 in a desired position by an etching etc., the diaphragm 30 and the cavity plate 10 are joined. At the time of this joining, a force is applied in a direction along the surface of the diaphragm 30 or the cavity plate 10, and the joining may be performed with a deviation from a desired joining position. Thereby, since the recessed part 36 will also be arrange | positioned and shifted | deviated from a desired position, there exists a problem that the area of the parts 40 and 41 will change from the original design size. And if the area of these parts 40 and 41 changes, it is possible that the ease of bending of the diaphragm 30 will change.

  For this reason, when the diaphragm 30 and the cavity plate 10 are joined, strict dimensional control is performed for manufacturing. In addition, assuming that the diaphragm 30 and the cavity plate 10 are displaced at the time of joining, several types of parts with different specifications are prepared for parts other than the diaphragm 30. And after joining the diaphragm 30, the ease of bending of the diaphragm 30 was checked, and parts were selected based on the check result. Thereby, the inkjet head 1 was able to obtain the desired performance at the beginning of the design.

  However, in order to obtain a desired performance at the time of designing, there are problems that several types of parts must be prepared and cost is increased. In addition, since it is necessary to provide an inspection process for checking the rigidity of the diaphragm 30, the manufacturing process is increased, and there is a possibility that the manufacturing time is excessive. From this, even if the vibration plate 30 is joined with a deviation from a desired position at the beginning of the design, it is considered that the above problem can be solved if the ejection performance of the manufactured inkjet head 1 does not change.

  Therefore, in order to investigate the relationship between the position of the recess 36 and the performance (deformation characteristics), the applicant of the present invention has three types of piezoelectric actuators in which the recess 36 is formed in the diaphragm 30 with different numbers of recesses 36 and different driving methods. These models were selected and simulations were performed on these models.

  Specifically, for each model of piezoelectric actuator, the position and size of the recess 36 are changed as parameters, and in each case, the piezoelectric actuator is moved to the pressure chamber side when a predetermined drive voltage is applied. The amount of deformation (deformation characteristics of the piezoelectric actuator) is determined. Further, the displacement amount at the time of joining the diaphragm 30 is a length between a position where the center of the recess 36 is to be arranged at the time of design and the center of the recess placed after joining.

  Here, this simulation will be described. First, the simulation method and analysis conditions will be described. In this simulation, the analysis was performed using the finite element method which is a general method. The specifications of the model piezoelectric actuator were set as shown in Table 1 below.

次に、解析を行う圧電アクチュエータの３種類のモデルについて図６〜１０を参照して説明する。

Next, three types of models of the piezoelectric actuator for analysis will be described with reference to FIGS.

  Model 1 is shown in FIG. 6 to FIG. 8, in which two concave portions 36 are formed symmetrically between adjacent pressure chambers 14 in a unimorph-deformable piezoelectric actuator (hereinafter “unimorph type”). It is. Then, when the position of the recess 36 overlaps the pressure chamber 14 and the partition wall 10a (FIG. 6, the first embodiment of the present invention), and the case where it overlaps only the pressure chamber 14 (FIG. 7, The position was changed so that the comparative example of the first embodiment of the present invention and the case where only the partition wall 10a was overlapped (FIG. 8, comparative example of the first embodiment of the present invention) can be taken. .

  The model 2 is shown in FIG. 9 and FIG. 10, and is one in which one concave portion 36 is formed between adjacent pressure chambers 14 in a piezoelectric actuator that undergoes unimorph deformation. And when the size of the recessed part 36 is formed large so that it may overlap over the two pressure chambers 14 adjacent to the partition 10a (FIG. 9, another embodiment of this invention), it will overlap only with the partition 10a. The size was changed so that it could be taken as a small size.

  The model 3 is a piezoelectric actuator (hereinafter referred to as “stacked type”) in which a plurality of piezoelectric layers stacked on a portion of the diaphragm facing the pressure chamber are deformed by the piezoelectric longitudinal effect, and the diaphragm is deformed by receiving this deformation directly. )), Similarly to the model 1, two concave portions 36 are formed symmetrically between the adjacent pressure chambers 14. More specifically, the diaphragm has the same structure as that of the diaphragm 30 of FIGS. 6 to 8, the piezoelectric layer is present in a state of being laminated only at the center of the portion of the diaphragm facing the pressure chamber, and the partition wall 10a. This structure does not exist in the vicinity, that is, in the portion where the groove 36 is formed.

Next, the analysis result will be described. First, the model 1 was analyzed in the case where the width of the recess 36 is constant at 30 μm and the distance 39 between the center position of the recess 36 and the center position of the partition wall 10a is changed by 5 μm. . Tables 2 and 3 below show the rate of increase in the deformation amount of the pressure chamber 14 when the center position of the recess 36 is arranged with a deviation of ± 5 μm from the desired initial position of the design. Table 2 below shows the analysis results when the center position of the recess 36 is shifted by 5 μm toward the pressure chamber 14, and Table 3 shows the center position of the recess 36 shifted by 5 μm toward the partition wall 10 a. The analysis result when arranged is shown.

また、表２、３をグラフにしたものを図１１、１２に示す。図１１は表２をグラフにした図であり、図１２は表３をグラフにした図である。ここで、図１１、１２において、凹部中心位置の設計値が０μｍ〜１９．３３μｍの区間（以下「A区間」という。）では、凹部３６が図８に示すモデル３のように配置されたものである。また、このA区間内の０μｍ〜１５μｍの区間では、凹部３６が図１０に示すモデル５のように配置される。そして、凹部中心位置の設計値が１９．３４μｍ〜４９．３３μｍまでの区間（以下「Ｂ区間」という。）では、凹部３６が図６に示すモデル１のように配置されたものである。さらに、凹部中心位置の設計値が４９．３４μｍ以上の区間（以下「Ｃ区間」という。）は、凹部３６が図７に示すようになる。

11 and 12 are graphs of Tables 2 and 3. FIG. FIG. 11 is a diagram in which Table 2 is graphed, and FIG. 12 is a diagram in which Table 3 is graphed. Here, in FIGS. 11 and 12, in the section where the design value of the center position of the recess is 0 μm to 19.33 μm (hereinafter referred to as “A section”), the recess 36 is arranged as in the model 3 shown in FIG. It is. Further, in the section of 0 μm to 15 μm in the section A, the concave portion 36 is arranged as in the model 5 shown in FIG. In the section where the design value of the recess center position is 19.34 μm to 49.33 μm (hereinafter referred to as “B section”), the recess 36 is arranged as in the model 1 shown in FIG. Further, in a section where the design value of the center position of the recess is 49.34 μm or more (hereinafter referred to as “C section”), the recess 36 is as shown in FIG.

  Here, the increasing rate of the deformation amount in the A to C section when the arrangement position of the recess 36 is shifted is compared. As shown in FIGS. 11 and 12, in the case where the concave portion 36 is arranged 5 μm off the pressure chamber 14 side and the case where the concave portion 36 is arranged 5 μm off the partition wall 10a side, the B section has a higher pressure chamber than the A section. It was found that the increase rate of the deformation amount of 14 was small. It was also found that the increase rate of the deformation amount is smaller in the B section than in the C section. That is, it was found that the rate of increase in the deformation amount of the pressure chamber 14 is small in the shape of the recess 36 as shown in FIG. Further, it was found that within the range of the B section, when the center of the concave portion is disposed at a position 40 μm away from the center of the partition wall 10a, the increase rate of the displacement amount becomes the smallest at 0.3%. When the thickness is 40 μm, the region 41 is larger than the region 40 in a sectional view.

  Next, for the model 2 shown in FIGS. 9 and 10, an analysis was performed in the case where the center position of the recess 36 was shifted from the center position of the partition wall 10a to the pressure chamber 14 side or the partition wall 10a side by 5 μm. In this analysis, a sample in which the size of the recess 36 was changed by 5 μm in a range of 30 μm to 140 μm in a cross-sectional view was used as a sample. The analysis results are shown in Tables 4 and 5 below. Table 4 shows the rate of increase in deformation when the center position of the recess 36 is displaced by 5 μm toward the pressure chamber 14, and Table 5 shows the center position of the recess 36 shifted by 5 μm toward the partition wall 10 a. It is a figure which shows the increase rate of the deformation amount at the time of arrange | positioning. Further, the size of the recess shown in Table 4 is the distance 42 shown in FIGS.

  Moreover, what was made into the graph about said Table 4, 5 is shown in FIG. 13 and 14, a section (hereinafter referred to as “D section”) in which the design value of the size of the recess is 0 μm to 34.33 μm is a case where the recess 36 is arranged as shown in FIG. .34 μm or more (hereinafter referred to as “E section”) is a case where the recesses 36 are arranged as shown in FIG.

  Here, the increasing rate of the deformation amount of the pressure chamber 14 in the sections D and E in FIGS. As shown in FIGS. 13 and 14, it was found that for both analysis results, the increase rate of the deformation amount is smaller in the D section than in the E section. Further, when the concave portion 36 is disposed on the pressure chamber 14 side with a deviation of 5 μm, the increase rate of the deformation amount is the smallest, 0.3%. Even when the recess 36 is disposed 5 μm away from the partition wall 10a, the rate of increase in deformation is 0.3%.

  Next, an analysis was performed on model 3, which is a multilayer piezoelectric actuator. The amount of displacement of the diaphragm 30 was analyzed under two conditions when the center position of the recess 36 was displaced by 5 μm from the center position of the partition wall 10a toward the pressure chamber 14 side and the partition wall 10a side. Furthermore, for the stacked model 3, two types of models having different configurations were used for the analysis. One is a piezoelectric layer 31 having a constraining layer disposed on the side opposite to the diaphragm 30 (hereinafter referred to as model 3-1), and the other is a piezoelectric layer 31 having no constraining layer. The one used (hereinafter referred to as model 3-2).

  Tables 6 and 7 below show the analysis results of the model 3-1 having the constrained layer, and Tables 8 and 9 below show the analysis results of the model 3-2 without the constraining layer.

また、表６〜９をグラフにしたものを図１５〜１８に示す。図１５、１６に示すように、モデル３−１では、凹部３６の中心位置が圧力室１４側及び隔壁１０a側に５μｍずれた場合の双方において、A〜C区間の全ての範囲で変形量の増加率は０％〜０．２％となることがわかった。また、図１７、１８に示すモデル３−２についても、A〜C区間の全ての範囲において、圧力室１４の変形量の増加率は０．９％〜３．２％程度であることもわかった。

Moreover, what graphed Tables 6-9 is shown to FIGS. As shown in FIGS. 15 and 16, in the model 3-1, in the case where the center position of the concave portion 36 is shifted by 5 μm to the pressure chamber 14 side and the partition wall 10a side, the deformation amount is in the entire range of the A to C sections. It was found that the increase rate was 0% to 0.2%. In addition, in the model 3-2 shown in FIGS. 17 and 18, the increase rate of the deformation amount of the pressure chamber 14 is about 0.9% to 3.2% in the entire range of the A to C sections. It was.

  Here, based on the above analysis results, the unimorph type (model 1) and the laminated type (models 3-1 and 3-2) are compared. As described above, in the laminated type, it has been found that the deformation amount of the pressure chamber 14 does not change even if a deviation occurs when the diaphragm 30 is joined. However, in the case of the unimorph type, when the concave portion 36 is disposed 5 μm away from the pressure chamber 14, the rate of increase in the deformation amount of the pressure chamber 14 in the entire range of the A to C sections as shown in Table 2 above. Varies from 0.3% to 9.1%. Further, even when the recess 36 is arranged at a distance of 5 μm on the side of the partition wall 10a, as shown in Table 3, the rate of increase in the deformation amount of the pressure chamber 14 varies by 0.3% to 8.4%. From this, it was found that the amount of deformation of the pressure chamber 14 in the unimorph type is easily changed when the arrangement position of the recess 36 is changed as compared with the laminated type.

  Next, the increase rate of the deformation amount of the pressure chamber 14 increased when the concave portion 36 was formed in the diaphragm 30 as compared with the case where the concave portion 36 was not formed was analyzed. The analysis results are shown in Tables 10 to 13 below. Table 10 shows the case of arrangement as in model 1 shown in FIGS. 6 to 8, and Table 11 shows the case of arrangement as in model 2 shown in FIGS. Table 12 shows the analysis result of the model 3-1, and Table 13 shows the analysis result of the model 3-2.

また、上記の表１０〜１３をグラフにしたものを図１９〜２２に示す。図１９、２１、２２のA〜C区間は、前述の図１１等にて説明した図６〜８に記載されたモデル１に該当する。また、図２０に示すＤ、Ｅ区間は、前述の図１３等にて説明したモデル２に該当する。

Moreover, what graphed said Tables 10-13 is shown to FIGS. 19, 21, and 22 correspond to the model 1 described in FIGS. 6 to 8 described in FIG. 11 and the like described above. Further, the sections D and E shown in FIG. 20 correspond to the model 2 described with reference to FIG.

  First, the increasing rate of the deformation amount of the unimorph type will be described with reference to Tables 10 and 11 and FIGS. As shown in Table 10 and FIG. 19, the rate of increase in the deformation amount of the pressure chamber 14 is 32.5% to 95.9 as compared to the case where the concave portion 36 is not formed in the diaphragm 30 in the section A to C. % Was also found to increase. It can also be seen that when the center position of the recess 36 is 35 μm from the center of the partition wall 10a, the rate of increase in deformation is the largest. Moreover, in the model 2, as shown in Table 11 and FIG. 20, it turned out that the increase rate of the deformation amount of the pressure chamber 14 increases 32.5%-96.4% within D and E area.

  Next, the increasing rate of the deformation amount of the stacked type will be described with reference to Tables 12 and 13 and FIGS. As shown in Table 12 and FIG. 21, the increase rate of the deformation amount of the pressure chamber 14 is confirmed to increase by 0.2% to 0.7% compared to that in which the concave portion 36 is not formed in the diaphragm 30. It was. Moreover, as shown in Table 13 and FIG. 22, the deformation amount of the pressure chamber 14 was confirmed to increase by 1.4% to 8.6%.

  From the above analysis results, it was found that the deformation amount of the pressure chamber 14 increases in the unimorph type when the concave portion 36 is formed in the vibration plate 30 as compared with the laminated type. Thus, in the unimorph type, since the diaphragm 30 is bent and deformed, it is considered that the amount of deformation that is convexly deformed toward the pressure chamber 14 changes depending on the rigidity of the diaphragm 30. However, in the case of the laminated type, it is considered that the amount of deformation by which the diaphragm 30 is convexly deformed toward the pressure chamber 14 is determined by the amount of deformation by which the piezoelectric layer 31 is deformed in the direction orthogonal to the plane of the diaphragm 30.

  Further, from the above analysis results, in the unimorph type, the deformation amount of the pressure chamber 14 is larger in the case where the concave portion 36 is formed in the vibration plate 30 than in the case where the concave portion 36 is not formed in the vibration plate 30. I found out that It was also found that the amount of deformation of the pressure chamber 14 varies greatly depending on the position where the recess 36 is disposed. The reason for such an analysis result will be described.

  In the unimorph type, the deformation characteristic, which is the deformation amount of the pressure chamber 14, changes depending on the ease of contraction of the piezoelectric layer 31 and the ease of bending of the diaphragm 30. The ease of contraction of the piezoelectric layer 31 indicates how much the piezoelectric layer 31 is deformed in a plane direction when a predetermined voltage is applied to the individual electrode 32. The ease of bending of the diaphragm 30 indicates how much the diaphragm 30 is deformed to the pressure chamber 14 side when a predetermined force is applied in a direction orthogonal to the surface of the diaphragm 30. Is.

  Here, the relationship between the analysis result and the deformation characteristics will be described with reference to FIGS.

  23 to 25 are diagrams in the case where the diaphragm 30 is joined to a desired position at the beginning of the design. In the diagram shown by the broken line, the diaphragm 30 is displaced to the pressure chamber 14 side during joining. Is the case. Further, the condition when the positional deviation occurs is limited to a condition in which the object on which the concave portion 36 overlaps does not change even when the positional deviation occurs. Furthermore, when a driving voltage is applied to the individual electrode 32 in the figure, the piezoelectric layer 31 on the right side of the recess 36 is contracted to the right.

  First, the change in the contraction amount of the piezoelectric layer 31 will be examined. The piezoelectric layer 31 shown in FIGS. 23 to 25 is contracted and deformed to the right side in the drawing by applying a driving voltage to the individual electrode 32 shown in the drawing. Here, a case where the concave portion 36 shown in FIG. 23 is arranged so as to have only a portion overlapping with the partition wall 10a will be described. When the diaphragm 30 is arranged without displacement, the piezoelectric layer 31 includes a portion that overlaps the pressure chamber 14 and a portion that overlaps the partition wall 10a. And in the part which overlaps with the partition 10a, since the diaphragm 30 and the partition 10a are joined, deformation | transformation of the diaphragm 30 is restrained by this joining surface. However, since the diaphragm 30 and the partition wall 10a are not joined at the portion overlapping the pressure chamber 14, the deformation of the diaphragm 30 is not restrained. Therefore, the piezoelectric layer 31 is easily deformed at the portion overlapping the pressure chamber 14, but is not easily deformed at the portion overlapping the partition wall 10a because it is restrained by the partition wall 10a.

  Here, in the piezoelectric layer 31, the size of the portion overlapping the partition wall 10 a is smaller when the vibration plate 30 is bonded to the right side in the drawing than when the diaphragm 30 is arranged without displacement. For this reason, the part to which the deformation of the piezoelectric layer 31 is restrained becomes small. Thereby, the piezoelectric layer 31 is easily contracted and deformed.

  Further, as shown in FIG. 24, in the case where the concave portion 36 is disposed so as to have a portion overlapping the pressure chamber 14 and the partition wall 10a, the piezoelectric layer 31 does not have a portion overlapping the partition wall 10a. In addition, even if the displacement of the arrangement position of the diaphragm 30 occurs, the piezoelectric layer 31 does not overlap the partition wall 10a. For this reason, the ease of contraction deformation of the piezoelectric layer 31 does not change even when a positional shift occurs.

  Furthermore, as shown in FIG. 25, even in the case where the concave portion 36 is arranged so as to have only a portion overlapping the pressure chamber 14, the piezoelectric layer 31 is separated from the partition wall even if the position of the vibration plate 30 is displaced. Since it does not overlap with 10a, the ease of contraction deformation of the piezoelectric layer 31 does not change.

  As described above, even if the positional deviation occurs when the diaphragm 30 is joined, the contraction of the piezoelectric layer 31 with respect to the case where the concave part 36 is disposed as shown in FIGS. It turns out that the deformation does not change.

  Next, a change in the deflection amount of the diaphragm 30 will be examined. First, the case where the recess 36 shown in FIG. 23 is arranged so as to have only a portion overlapping the partition wall 10a will be described. As shown in FIG. 23, when the diaphragm 30 and the cavity plate 10 are joined, the restraining portion 50 exists on the boundary between the diaphragm 30, the partition wall 10 a, and the pressure chamber 14. When a predetermined force is applied to the diaphragm 30, the right portion of the partition wall 10a bends with the restraint portion 50 as a support portion. Further, in the case of such a diaphragm 30, a portion having the shortest thickness from the restraining portion 50 to a predetermined position on the surface of the diaphragm 30 in a sectional view is bent. Here, in FIG. 23, the portion from the restraining portion 50 to the predetermined position 53 of the recess 36 has the smallest thickness. Such a portion is referred to as a constricted portion 52.

  As shown in FIG. 23, when the positional deviation occurs when the diaphragm 30 is joined, the recess 36 is arranged so as to be shifted to the right side in the drawing. Thereby, since the recessed part 36 approaches the restraint part 50, the length from the restraint part 50 to the recessed part 36 becomes short. Accordingly, the constricted portion 54 when the diaphragm 30 is displaced is smaller than the constricted portion 52 when the diaphragm 30 is not displaced. Thereby, since the rigidity of the constricted part 54 is smaller than that of the constricted part 52, the diaphragm 30 is more easily bent than in the case where it is arranged at a desired position.

  Further, as shown in FIG. 24, in the case where the concave portion 36 is disposed so as to overlap the pressure chamber 14 and the partition wall 10a, the concave portion 36 is restrained in a plan view even when the concave portion 36 is displaced. It overlaps with the part 50. For this reason, the recessed part 36 does not approach or leave the restraint part 50. For this reason, the magnitude | size from the restraint part 50 to the predetermined position 61 on the recessed part 36 does not change. Accordingly, since the size of the constricted portion 62 does not change, the rigidity does not change, and the ease of bending of the diaphragm 30 does not change.

  Furthermore, as shown in FIG. 25, in the case where the concave portion 36 is arranged so as to have only a portion overlapping the pressure chamber 14, when the diaphragm 30 is shifted to the right side in the figure, the concave portion 36 is also shifted to the right side. End up. Thereby, since the recessed part 36 leaves | separates from the restraint part 70, the magnitude | size from the restraint part 70 to the recessed part 36 becomes large. Accordingly, the constricted portion 74 when displaced is larger than the constricted portion 72 when not displaced, and thus rigidity is increased. Thereby, the diaphragm 30 becomes difficult to bend. Further, when the diaphragm 30 is deformed, the thinnest portion of the recess 36 bends. When the thinnest portion of the concave portion 36 is displaced toward the center of the pressure chamber 14 due to the positional deviation, the region that is depressed toward the pressure chamber 14 due to the bending of the diaphragm 30 is reduced. For this reason, the deformation amount of the volume of the pressure chamber 14 becomes small.

  As described above, even when the displacement of the arrangement position of the diaphragm 30 occurs, if the concave portion 36 is arranged as shown in FIG. 23, the concave portion 36 arranged as shown in FIGS. It was found that the ease of bending of the diaphragm 30 is less likely to change compared to.

  As described above, in the case where the concave portion 36 has a portion extending from the portion overlapping the pressure chamber 14 to the portion overlapping the partition wall 10a in a plan view, even if the displacement of the diaphragm 30 occurs, Since the deformation of the diaphragm 30 and the ease of bending of the diaphragm 30 are small, even if the position of the recess 36 is displaced when the diaphragm 30 is joined, the amount of deformation of the pressure chamber 14 hardly changes. For this reason, even if an error occurs in the arrangement position of the diaphragm 30 at the time of manufacture, fluctuations in the deformation characteristics of the piezoelectric actuator can be suppressed.

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

  As shown in FIGS. 26 and 27, in the case where the recess 36 is formed as in the first embodiment, an auxiliary recess 80 extending in the scanning direction is formed between the adjacent recesses 36 (first). 1 modified form). In the first modification, as compared with the diaphragm 30 in which the auxiliary recess 80 is not provided between the adjacent recesses 36, only the region overlapping the desired pressure chamber 14 of the diaphragm 30 when ejecting ink droplets. When this is deformed, it is possible to prevent crosstalk that propagates to a region overlapping with the adjacent pressure chamber 14.

  Moreover, you may arrange | position so that two adjacent pressure chambers 14 may be straddled across the partition 10a like the recessed part 36A shown in FIG. 9 (2nd modification). 28 and 29 show a top view and a cross-sectional view of the second modified embodiment. From the above analysis results, even if the concave portion 36A has such a shape, even when the positional deviation is uttered in the concave portion 36A, the rate of increase in the deformation amount of the pressure chamber 14 can be reduced. From this, even if an error occurs in the positional deviation, it is possible to suppress the variation in the deformation characteristics of the piezoelectric actuator 3.

  Here, the method of forming the piezoelectric layer 31 by the AD method or the like has been described above. However, a ceramic sheet material is laminated in a region where the concave portion 36 of the diaphragm 30 is not formed, and is fired. Also good.

  The ink jet head 1 of the embodiment described above is a serial type head that ejects ink onto the recording paper while moving in the width direction of the recording paper, but extends over the entire width of the recording paper. The present invention can also be applied to a line-type ink jet printer having a plurality of nozzle rows.

  Furthermore, although the said embodiment and its modification are examples which applied this invention to the inkjet head which discharges an ink from a nozzle, the liquid transfer apparatus which can apply this invention is not restricted to an inkjet head. For example, a conductive paste is sprayed to form a fine wiring pattern on the substrate, an organic light emitter is sprayed to the substrate to form a high-definition display, and an optical resin is sprayed to the substrate. The present invention can be applied to various liquid transfer apparatuses for forming a micro optical device such as an optical waveguide.

  Furthermore, the present invention is also applied to a liquid transfer device for transferring a liquid other than ink, such as a reagent, a biological solution, a wiring material solution, an electronic material solution, a refrigerant, and a fuel, and a liquid transfer device without a nozzle for transferring these liquids. It is possible to apply.

1 is a schematic perspective view of an ink jet printer according to an embodiment of the present invention. 2 is a plan view of the inkjet head 1. FIG. FIG. 3 is a partially enlarged plan view of FIG. 2. It is the II sectional view taken on the line of FIG. It is the II-II sectional view taken on the line of FIG. It is a partially expanded sectional view of the partition 10a vicinity of FIG. FIG. 4 is a partially enlarged cross-sectional view when a recess 36 overlaps only the pressure chamber 14. It is a partially expanded sectional view in case the recessed part 36 overlaps only with the partition 10a. It is a partially expanded sectional view of the vicinity of the partition wall 10a of the piezoelectric actuator 3 having a recess 36A. It is a partially expanded sectional view in case the recessed part 36A overlaps only with the partition 10a. It is a figure which shows the analysis result when the recessed part 36 of this embodiment becomes large from a design value. It is a figure which shows the analysis result when the recessed part 36 of this embodiment becomes small from a design value. It is a figure which shows the analysis result when the recessed part 36A of the piezoelectric actuator shown to FIG. 9, 10 becomes large from a design value. It is a figure which shows the analysis result when the recessed part 36A of the piezoelectric actuator shown to FIG. 9, 10 becomes small from the design value. It is a figure which shows the analysis result when the recessed part 36 of a direct type | mold piezoelectric actuator becomes large from a design value. It is a figure which shows the analysis result when the recessed part 36 of a direct type | mold piezoelectric actuator becomes small from a design value. It is a figure which shows the analysis result when the recessed part 36 becomes large from a design value about the thing without a constrained layer in a direct type | mold. It is a figure which shows the analysis result when the recessed part 36 becomes small from a design value about the thing without a constrained layer in a direct type | mold. It is a figure which shows the increase rate of the deformation amount of the pressure chamber 14 when the recessed part 36 is formed in the diaphragm 30 in this embodiment. It is a figure which shows the increase rate of the deformation amount of the pressure chamber 14 when the recessed part 36A is formed in the diaphragm 30 in the piezoelectric actuator of FIG. FIG. 17 is a diagram showing an increase rate of the deformation amount of the pressure chamber when the concave portion is formed in the vibration plate in the piezoelectric actuator of FIGS. It is a figure which shows the increase rate of the deformation amount of the pressure chamber 14 when the recessed part 36 is formed in the diaphragm 30 in the piezoelectric actuator of FIG. It is a partial expanded sectional view of the piezoelectric actuator arrange | positioned so that the recessed part 36 may have only a part which overlaps with the partition 10a. FIG. 4 is a partially enlarged cross-sectional view of a piezoelectric actuator arranged such that a recess has a portion that overlaps a pressure chamber and a partition wall. FIG. 4 is a partial enlarged cross-sectional view of a piezoelectric actuator arranged so that a recess has only a portion overlapping with a pressure chamber. It is a top view of the piezoelectric actuator of the 1st modification. It is the III-III sectional view taken on the line of FIG. It is a top view of the piezoelectric actuator of the 2nd modification. It is the IV-IV sectional view taken on the line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3 Piezoelectric actuator 10a Partition 14 Pressure chamber 15, 16 Communication hole 20 Nozzle 30 Diaphragm 31 Piezoelectric layer 32 Individual electrode 33 Insulating film 34 Common electrode 36, 37 Recess 38 Hill 40, 40A Pressure chamber 14 41, 41A overlapping portions 50, 60, 70 overlapping with partition wall 10a Restraining portion 80 Auxiliary recess

Claims (6)

A flow path unit formed such that a pressure chamber communicating with the liquid inlet and the liquid outlet opens on a predetermined surface;
A piezoelectric actuator provided on one surface of the flow path unit so as to cover the pressure chamber;
In a liquid transfer device comprising:
The piezoelectric actuator is
A diaphragm fixed to the predetermined surface of the flow path unit so as to close the opening of the pressure chamber;
A piezoelectric layer laminated on the diaphragm;
On one surface side of the piezoelectric layer, a first electrode formed in a region overlapping the pressure chamber in plan view;
A second electrode formed at least in a region facing the first electrode on the other surface side of the piezoelectric layer, and unimorph deformation of the diaphragm by contraction of the piezoelectric layer,
The diaphragm has a recess on a surface opposite to the flow path unit,
The concave portion is formed in a region that does not overlap with the first electrode in a plan view with a width that occupies from a position corresponding to the inside of the pressure chamber to a position corresponding to the outside of the pressure chamber. A liquid transfer device.   The liquid transfer device according to claim 1, wherein the recess extends so as to surround the pressure chamber in a plan view.   3. The liquid transfer device according to claim 1, wherein the concave portion includes a first portion overlapping with the pressure chamber in a plan view and a second portion overlapping outside the pressure chamber. The flow path unit includes a plurality of the pressure chambers, and the plurality of pressure chambers are arranged in a predetermined direction,
The diaphragm includes a plurality of the concave portions overlapping with each of the plurality of pressure chambers in a plan view,
A recess belonging to one pressure chamber and a recess belonging to the other pressure chamber are formed between the two pressure chambers arranged adjacent to each other in the predetermined direction, and the two recesses are connected to each other. The liquid transfer device according to claim 1, wherein the liquid transfer device is partitioned by a hill portion having no recess.   The liquid transfer device according to claim 4, wherein an auxiliary recess that extends in a direction perpendicular to the predetermined direction without being connected to the two recesses is formed in the hill portion. The first electrode and the second electrode are for applying an electric field parallel to the thickness direction to the piezoelectric layer,
The liquid transfer device according to claim 1, wherein the piezoelectric layer is polarized in the thickness direction.

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