JP4560673B2 - Ink jet head and droplet discharge device using the same - Google Patents

Description

  The present invention relates to an ink jet head that applies pressure to ink and causes ink droplets to fly from nozzles to form an ink image on a print medium, and a droplet discharge device using the same.

  For example, as described in Patent Document 1, there is known an ink jet head that ejects ink from nozzles by changing the volume of a pressure chamber using a piezoelectric actuator and applying pressure to the ink.

  FIG. 12 shows a conventional example of an ink jet head using a piezoelectric element, which includes a piezoelectric actuator 14, a high-rigidity housing 12, and a plate group 26. The plate group 26 includes a nozzle plate 2 on which a plurality of nozzles 1 are formed, a flow path substrate 3, and a diaphragm plate 10 on which a diaphragm 8 is formed. The flow path substrate 3 includes a chamber plate 5 and a restrictor plate 7. The plate group 26 is positioned and joined to the high-rigidity housing 12 in which the common ink passage 13 is formed.

  The piezoelectric actuator 14 includes a plurality of piezoelectric elements 15 and a fixing member 16 that fixes the piezoelectric elements 15. Each of the plurality of piezoelectric elements 15 corresponds to the pressure chamber 4 formed in the chamber plate 5. The piezoelectric element 15 is joined to the diaphragm 8 of the diaphragm plate 10 through the opening of the high-rigidity housing 12. Furthermore, the fixing member 16 is formed with individual electrodes 17 for sending an electric signal independent of an external drive circuit (not shown) to each piezoelectric element 15. When a selective electrical signal is applied to the piezoelectric element 15 from the external drive circuit, the piezoelectric element 15 expands and contracts. This expansion and contraction changes the volume of the pressure chamber 4 via the vibration plate 8 and changes in the pressure of the ink filled in the pressure chamber 4. This pressure change causes ink to be ejected from the nozzle 1 as ink droplets.

  The processing accuracy of the opening shape of the nozzle 1 greatly affects the ink ejection characteristics of the inkjet head. In order to suppress variations in positional accuracy of the plurality of nozzles 1, high processing accuracy is required when the nozzle plate 2 is manufactured. Usually, the nozzle plate 2 is formed by a stainless precision pressing method, a laser processing method, nickel electroforming, or the like.

  Pressure chambers 4 are formed in a row in the chamber plate 5 constituting the flow path substrate 3, and a restrictor 6 is formed in the restrictor plate 7. The restrictor 6 connects the common ink chamber 13 and the pressure chamber 4 and controls ink inflow into the pressure chamber 4.

  The diaphragm plate 10 has a diaphragm 8 and a filter unit 9. The diaphragm 8 efficiently transmits the displacement of the piezoelectric vibrator 15 to the pressure chamber 4. The filter unit 9 removes dust and the like in the ink flowing into the restrictor 6 from the common ink passage 13. The filter portion 9 is formed by an elastic filter plate. The chamber plate 5, the restrictor plate 7 and the diaphragm plate 10 are made by a stainless steel etching process or a nickel electroforming process.

  The high-rigidity housing 12 is formed by cutting stainless steel or the like, and an ink introduction pipe 18 that guides ink from an ink cartridge (not shown) to the common ink passage 13 is joined. An opening for inserting the piezoelectric element 15 is formed in a part of the high-rigidity housing 12 in order to bond the piezoelectric element 15 to the diaphragm plate 10.

  In recent years, in the ink jet head as described above, it is required to form the nozzles 1 with higher density. However, when the nozzle 1 is further densified, it is difficult to provide an opening for each piezoelectric element 15 in terms of processing accuracy. That is, the expansion / contraction amount of the piezoelectric element 15 is very small (about 0.5 μm), and the deformation amount of the plates changes due to a slight difference in structure and dimensional value, which affects the ejection characteristics. This is because high machining accuracy is required.

  Therefore, in order to solve the above problems and mount the nozzles at high density and discharge ink stably, for example, Patent Document 3 discloses a non-bonding region in the vicinity of the piezoelectric element 15 in the ink chamber being bonded to the diaphragm plate 10. A structure has been proposed in which an adhesive region is formed only in the side region of the ink chamber 13 with good processing accuracy.

  With such a structure, if the joining region has a high rigidity housing having high flatness, the flatness of the diaphragm plate diaphragm and the contact portion of the piezoelectric vibrator is corrected, and excellent ink discharge is possible. Has an effect.

Japanese Patent Laid-Open No. 1-115638 (second page, FIG. 2)

JP 58-119872 A Japanese Patent Laid-Open No. 6-8422 (page 4, FIGS. 7, 8, and 9)

  However, when the diaphragm plate is bonded to the high-rigidity housing as described above, the piezoelectric element insertion opening becomes wider if the high-rigidity housing and the diaphragm plate are not bonded in the vicinity of the portion where the piezoelectric element and the diaphragm plate are bonded. End up.

  Therefore, if ink droplets are ejected from a plurality of nozzles almost simultaneously, the deformation of the plate group surface increases due to the expansion and contraction of the plurality of piezoelectric elements, affecting the ink droplet ejection performance, and so-called crosstalk is generated. There's a problem.

  In addition, the structure in which a large number of openings corresponding to each piezoelectric element are formed on a flat surface of a high-rigidity housing has a problem that high-density mounting of nozzles is difficult because of the processing accuracy of the openings as described above.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet head that solves the above-described conventional problems and a droplet discharge device using the ink jet head.

  Specifically, an object of the present invention is to provide an ink jet head capable of reducing the amount of deformation of the surface of the nozzle plate group during ejection and suppressing the occurrence of crosstalk, and a droplet ejection apparatus using the same.

  Another object of the present invention is to provide an ink jet head that enables high-density mounting of piezoelectric elements and a droplet discharge device using the ink jet head.

  In order to achieve the above object, the present invention provides a nozzle plate having a plurality of nozzle openings for discharging ink droplets, a flow path substrate in which a plurality of pressure chambers corresponding to the nozzle openings are arranged, and sealing the pressure chambers. A diaphragm plate having a diaphragm formed to stop; a piezoelectric element group disposed so as to sandwich the diaphragm at a position facing the pressure chamber; a housing for housing the piezoelectric element group; and the diaphragm plate; An ink chamber plate disposed between the housing and the housing, the housing having a convex portion on a side in contact with the diaphragm plate, and the convex portion being inserted into each of the piezoelectric elements. One feature resides in that the ink chamber plate is disposed so as to surround the convex portion while being formed by the opening groove portion and the comb convex portion.

  Another feature of the present invention is that at least the convex portion of the housing is formed of a member having higher rigidity than the diaphragm plate.

  Another feature of the present invention is that the ink chamber plate includes a common ink chamber that supplies ink to each pressure chamber, and an ink supply path provided in the housing at both ends in the longitudinal direction of the common ink chamber. It is configured to be connected and fixed to the housing.

  Another feature of the present invention resides in that the pressure chambers arranged in the flow path substrate are arranged so as to face each other around a nozzle row in which a plurality of nozzle openings are arranged in a row.

  Another feature of the present invention resides in that one end of the piezoelectric element group is formed on the same plane and bonded to the diaphragm plate, and the other end is fixed to a fixing member.

  Another feature of the present invention is that a nozzle plate having a plurality of nozzle openings for discharging ink droplets, a flow path substrate in which a plurality of pressure chambers corresponding to the nozzle openings are arranged, and the pressure chambers are sealed. A diaphragm plate having a formed diaphragm, a piezoelectric element group disposed so as to sandwich the diaphragm at a position facing the pressure chamber, a housing for housing the piezoelectric element group, and the diaphragm plate and the housing. An ink chamber plate disposed between the housing, the housing having a convex portion on a side in contact with the diaphragm plate, the convex portion having a comb-shaped opening groove portion and a comb-shaped portion into which each of the piezoelectric elements is inserted. A connecting member for connecting the comb-shaped convex portions to each other is provided.

  Another feature of the present invention resides in that a plurality of the nozzle rows are provided and the center of the connecting member is positioned between the nozzle rows.

  Another feature of the present invention resides in that the height of the comb-shaped convex portion is smaller than the thickness of the ink chamber plate. Further, the height of the comb-shaped convex portion is made larger than the depth of the comb-shaped opening groove portion.

  Another feature of the present invention resides in that the connecting member is provided at a substantially central portion of the comb-shaped opening groove. Other features and advantages of the present invention will be more clearly understood from the following description.

  In the present invention, a convex portion is formed on the surface of the high-rigidity housing on the diaphragm plate side, and comb-shaped opening grooves for inserting each piezoelectric element and comb-shaped convex portions are formed on the convex portion. Since the end face is fixed to the diaphragm, the amount of deformation of the plate group is reduced, and the expansion and contraction of the piezoelectric element can be efficiently converted into a change in ink pressure, and the occurrence of crosstalk can be reduced.

  Further, according to the present invention, the convex portion is formed on the surface of the high rigidity housing on the diaphragm plate side, and the comb-shaped opening is formed in the convex portion. It is possible to use the same processing method as that used for processing, and there is an effect that processing can be performed with high accuracy.

  Further, when the comb-shaped convex portions are connected by a connecting member, the rigidity of the diaphragm plate can be further increased, and the occurrence of crosstalk can be further reduced. Therefore, even when a plurality of piezoelectric elements are driven simultaneously, it is possible to obtain ejection characteristics equivalent to those of single driving, and to provide a high-quality printing apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 11 is a schematic configuration diagram showing an embodiment of a droplet discharge device according to the present invention. In the figure, reference numeral 28 denotes a recording unit, which includes a plurality of inkjet heads 11 corresponding to the printing width and an ink cartridge 29 that supplies ink to the inkjet heads 11.

  The recording unit 28 is slidably supported on the guide shaft 30. Further, it is connected to the power transmission member 31 and is moved along the guide shaft 30 by the drive source 32.

  At the time of printing, the recording unit 28 is stationary on the printing area. On the other hand, the print medium 33 faces the inkjet head 11 and is conveyed by the conveyance roll 34 in a direction orthogonal to the moving direction of the recording unit 31. Ink is ejected from the nozzles of the inkjet head 11 to the print medium 33 in accordance with a recording signal to form an image.

  FIG. 1 is a configuration diagram showing an embodiment of an ink jet head used in a droplet discharge device according to the present invention, and an example in which two nozzle opening rows for discharging ink droplets are arranged for high-density mounting. Show. 2 is a cross-sectional view of the inkjet head of the present invention, and FIG. 3 is a detailed cross-sectional view in which the high-rigidity housing 12 is divided at the center in the nozzle row direction.

  As shown in FIGS. 1 and 2, a nozzle plate 2 in which a plurality of nozzles 1 are formed, a flow path substrate 3 composed of a chamber plate 5 and a restrictor plate 7, a diaphragm plate 10 having a diaphragm 8, A plate group 26 that holds each plate and includes an ink chamber plate 27 having a common ink passage 13b is fixed to the high-rigidity housing 12 having the common ink passage 13a.

  In addition, a piezoelectric actuator 14 including a plurality of piezoelectric elements 15 and a fixing member 16 for fixing the piezoelectric elements 15 is fixed to the diaphragm plate 10 at a position where each piezoelectric element 15 and each pressure chamber 4 face each other.

  The fixed member 16 of the piezoelectric actuator 14 is formed with individual electrodes 17 for sending an electric signal independent of an external drive circuit (not shown) to each piezoelectric element 15. When a selective electrical signal is applied to the piezoelectric element 15 from the external drive circuit, the piezoelectric element 15 expands and contracts. This expansion / contraction becomes a change in the volume of the pressure chamber via the diaphragm 8 and a change in the pressure of the ink filled in the pressure chamber. This pressure change causes ink to be ejected from the nozzle 1 as ink droplets.

  The ink chamber plate 27 includes a common ink chamber 13b that supplies ink to each pressure chamber 4, and is connected to an ink supply path 13a provided in the high-rigidity housing 12 at both longitudinal ends of the common ink chamber 13b. Has been.

  The pressure chambers 4 formed in the flow path substrate 3 are arranged so as to face each other with the row of nozzle openings 1 as a center. This arrangement method is described in detail in, for example, Japanese Patent Application No. 2002-352127 of a previous application by the same applicant as the present application.

  One end of the plurality of piezoelectric elements 15 of the piezoelectric actuator 14 is formed in the same plane, the other end is fixed to the fixing member 16, and the comb-shaped piezoelectric element groups are arranged to face each other.

  The high-rigidity housing 12 has an opening hole 12a for inserting the piezoelectric actuator 14 as shown in FIG. A convex portion 12e is formed on the surface of the high-rigidity housing 12 facing the diaphragm plate 10, and a comb-shaped opening groove 12d is formed in the convex portion 12e. The convex portion 12 e is fixed by fitting into the opening hole 35 of the ink chamber plate 27. The piezoelectric element 15 is inserted into the comb-shaped opening groove 12d formed in the convex portion 12e. Further, by forming the comb-shaped opening groove 12d, the tip surface of the comb-shaped convex portion 12f formed in the convex portion 12e is fixed to the diaphragm plate 10.

  In order to form the comb-shaped opening groove 12d and the comb-shaped convex portion 12f in the convex portion 12e as described above, the rod-shaped piezoelectric body is divided into a plurality of comb-shaped piezoelectric elements 15 with a dicing saw or a wire saw. A similar processing method can be used. That is, by processing in this way, it is easy to make the dimensional accuracy of the comb-shaped groove 12d and the comb-shaped convex portion 12f the same as the processing accuracy of the piezoelectric actuator 14, and the position of the piezoelectric actuator 14 and the high-rigidity housing 12 is easy. It is possible to improve accuracy and assembly accuracy. Therefore, the piezoelectric actuator 14 can be mounted with high density, and the nozzle body can be formed with high density.

  Further, since the comb-shaped convex portion 12f of the high-rigidity housing 12 is fixed to the diaphragm plate 10, the deformation of the plate group 26 due to the expansion and contraction of the piezoelectric element 15 that occurs when ink droplets are ejected can be supported by the comb-shaped convex portion 12f. Thus, variations in ink characteristics such as crosstalk, which is a problem in the prior art, can be prevented.

  In order to support the plate group 26 as described above, the rigidity of the housing 12 is preferably higher than that of the plate group 26, and at least the rigidity of the convex portion 12e of the housing 12 is higher than the rigidity of the diaphragm plate 10. desirable.

  Further, when the comb-shaped opening groove 12d is formed in the convex portion 12e, the depth of the groove 12d is kept at a depth that does not form a groove on the plate bonding surface 12g around the convex portion 12e. desirable. That is, the depth of the groove 12d is smaller than the height of the convex portion 12e. The reason is that if the groove is formed up to the plate bonding surface 12g of the high-rigidity housing 12, the adhesive cannot completely fill the groove when the plate is bonded, and there is a possibility that a slight gap is generated. This is because the ink may ooze out from the common ink passage 13b through the gap and the actuator 14 may be damaged.

  Next, one structural example of the piezoelectric body used in the ink jet head according to the present invention will be described with reference to FIG.

  Internal electrodes 21 and 23 and an external electrode 22 are formed on the piezoelectric body 50 used as the piezoelectric element 15. The internal electrodes 21 in contact with both ends of the piezoelectric body 50 and the internal electrodes 23 arranged at the center are alternately stacked in the direction perpendicular to the displacement of the piezoelectric element. The internal electrodes 21 are electrically connected to the external electrodes 22 formed on both end faces of the piezoelectric body 50, respectively. As a result, an inactive portion that does not generate an electric field is formed in the central region of the piezoelectric body 50, and active portions that are displaced by the electric field are formed at both ends.

  Next, a process for manufacturing a voltage actuator from the voltage body 50 will be described with reference to FIGS.

  First, as shown in FIG. 5, the other end of the piezoelectric body 50 is fixed to a conductive fixing member 16 so that one end is a free end. Then, as shown in FIG. 6, the voltage body 50 is cut using a dicing saw, a wire saw, or the like so that there is an active portion that generates displacement due to an electric field in each piezoelectric element and an inactive portion that does not generate displacement. To do. Next, as shown in FIG. 7, the cut portion is filled with the conductive adhesive 25 to electrically connect the internal electrode 23 and the fixing member 16. Moreover, it fixes with the conductive adhesive 25 so that the external electrode 22 and the fixing member 16 may be conducted. As a result, two piezoelectric element bodies 51 are formed from the piezoelectric body 50. Note that the conductive adhesive 25 filling the cut portion does not need to completely fill the cut portion, but the internal electrode 23 on the cut surface and the fixing member 16 need to be electrically connected.

  Next, as shown in FIG. 8, flexible printed cables (FPC) 24 are attached to both side surfaces of the fixing member 16 so that voltages can be individually applied to the common electrode 22 side. Finally, the piezoelectric element body 51 is cut at a constant pitch so as to correspond to the pressure chamber 4 and divided into a plurality of piezoelectric elements 15. As a result, the two rows of piezoelectric element groups are formed on the single fixing member 16 only by holding one piezoelectric body 50 once on the fixing member, so that the positional accuracy between the two rows is increased. Is possible.

  Naturally, the piezoelectric element body 51 formed in the shape of two rods may be divided into a plurality of piezoelectric elements after being formed from the beginning as shown in FIG. In this case, the positional accuracy between the piezoelectric element bodies 51 is inferior, but the application amount of the conductive adhesive 25 applied between the piezoelectric element bodies is small, and the workability is improved at the same time.

  FIG. 9 shows the relationship between the number of adjacent nozzles driven and the change in the droplet velocity ratio in the inkjet head according to the present invention. Here, the speed ratio will be described. The deformation of the plate group is basically the same as the deformation of the beam supported at both ends. 48 (or 49th nozzle) at the time of the allocation of the crosstalk is the worst due to the decrease in rigidity. Therefore, the “speed ratio” in the present invention refers to the discharge speed of the basic nozzle when the nozzles on both sides of the basic nozzle (the 48th nozzle) are driven and the number of drive nozzles is increased, and the basic nozzle only. This represents the ratio to the discharge speed during driving. The deformation ratio is the ratio between the change in weight of the piezoelectric element and the deformation of the plate group 26.

  The head used in this experiment is a head having a nozzle diameter of 50 μm, a pitch between nozzles of about 37.5 dpi, and a plurality of nozzles arranged in a row. The amount of ink droplets is about 60 pl (picoliter), and the ink droplet ejection speed. Is an example of a head configured to be approximately 10 m / s. According to this example, as the number of nozzles is increased, the droplet speed gradually decreases, the drop in speed is substantially constant from a certain number (for example, 16), and is substantially constant even if the number of nozzles driven is increased further. It became. In the above example, the case of one nozzle row has been described. However, even in the case of two rows described in the embodiment of the present invention, the relationship between the speed ratio and the number of nozzles driven does not change.

  FIG. 13 shows the relationship between the number of nozzles driven and the deformation ratio in the vicinity of the nozzles of the nozzle plate 2 which is each of the stacked plate groups in the inkjet head according to the present invention. Also in this case, as the number of nozzles driven is increased, the amount of deformation is substantially constant from a certain number. It was found that it almost coincided with the number shown in FIG. It has been experimentally found that such a tendency shows a similar tendency when the nozzle pitch is 35 dpi or more and the number of nozzles is about 45 or more. This experimental value is an example.

  Furthermore, FIG. 14 shows the relationship between the thickness of the comb portion, the deformation amount, and the speed fluctuation rate due to crosstalk in the ink jet head according to the present invention. As described in the above embodiments, the comb-shaped opening groove 12d and the comb-shaped convex portion 12f are formed in the high-rigidity housing 12 so as to partition the piezoelectric elements 14, and are fixed to the comb-shaped convex portion 12f and the diaphragm plate 10. As a result, the rigidity of the plate group 26 in the region of the opening 12a is increased, so that the speed variation rate can be reduced. In other words, according to the above example, as can be seen from the broken line in FIG. 14, if the thickness δ of the comb-shaped convex portion is 60% or more of the total thickness of the stacked plates, the speed fluctuation due to crosstalk is 20% or less. It became possible to do.

  Although the ink jet head and the droplet discharge apparatus using the ink jet head according to the present invention have been described above, various modifications can be made without changing the basic idea. For example, the high-rigidity housing 12 can be made of a stainless material for the purpose of corrosion resistance with various inks. Further, as shown in FIG. 1, if positioning holes A and B are provided at both ends of the high-rigidity housing portion 12, the plate group 26, and the piezoelectric actuator 14, the members are assembled based on the holes. This makes it easier to align the plates. Furthermore, since the insertion groove for the piezoelectric element 15 is integrally formed in the high-rigidity housing portion 12, the piezoelectric element 15 can be assembled with a high degree of accuracy with little displacement by assembling the piezoelectric element 15 based on that portion.

  According to the present invention, when laminating and bonding the thin plates, the comb-shaped opening groove is formed integrally with the housing. As compared with the above, the opening groove and each plate can be aligned with higher accuracy. In addition, when such high-precision machined parts are configured as separate parts, there is a possibility that the precision may be deteriorated during handling and during the above-mentioned bonding, but when integrally formed as in the present invention, There is no problem.

  Next, another embodiment of the high-rigidity housing used in the inkjet head according to the invention will be described with reference to FIG. In this embodiment, in order to further increase the rigidity of the plate group 26, a connecting column 12i is provided.

  That is, the convex portion 12e is formed in the high-rigidity housing 12, the comb-shaped opening groove portion 12d is formed in the convex portion 12e, and the connecting column 12i is provided in a direction perpendicular to the longitudinal direction of the opening groove portion 12d. The connecting column 12i connects the comb-shaped convex portions 12f to each other, and is provided within the range of the opening groove 12d, but is most preferably provided at the center of the opening groove 12d. When there are a plurality of nozzle 1 rows, it is desirable that the center of the connecting column 12i be located between the nozzle rows.

  With this configuration, the comb-shaped convex portions 12f arranged in a row are connected to each other. As a result, the rigidity of the comb-shaped convex portions 12f and the plate group can be increased, and deformation of plates during ink droplet ejection can be achieved. Can be further reduced. Further, since the width of the comb-shaped convex portion 12f is very thin, about 0.1 to 0.2 mm, there is a possibility that the comb-shaped convex portion 12f may be deformed due to the falling of the dicing grindstone during the processing. There is also an effect that can be prevented.

  The configuration of the present invention described above is particularly effective when the mounting size is limited. For example, in order to realize a printing resolution of 600 dpi, when the number of nozzles is 192 and the head width is about 8 mm or less, a comb-like member is provided between the openings of the housing into which the piezoelectric element 15 is inserted. Although difficult, if the groove is formed in the convex portion after the high-rigidity housing 12 is convex as in the present invention, it becomes easy to form a member between the piezoelectric elements. In addition, since these members are integrally formed with the housing, the cost can be reduced.

  Further, in the embodiment shown in FIGS. 1 and 10, the thickness of the convex portion 12 e formed in the high-rigidity housing 12 (= the height δ of the comb-shaped convex portion 12 f + the base portion) is greater than the thickness of the ink chamber plate 27. Slightly smaller is desirable. That is, it is more desirable that the convex portions and the ink chamber plate 27 have the same thickness, but it is difficult to process them so that they are exactly the same. Actually, the convex or concave shape is in between due to variations in processing accuracy. A step will occur. Thus, by designing the thickness of the convex portion 12e to be slightly smaller, even if the flatness of the tip surface of the convex portion 12f is somewhat worse, the surface to be bonded to the ink chamber plate 27 is further flat. If about 10 μm is ensured, the influence on the characteristics due to the warpage and deformation of the plate group 26 can be reduced. With the above configuration, the plate group is bonded only to the ink chamber plate. The plate group 26 itself is thinner than the ink chamber plate and has a structure in which warpage and deformation are likely to occur. However, by adhering to the ink chamber plate 27 having higher strength than the plate group 26, the surface of the ink chamber plate 27 is followed. In other words, if the flatness of the ink chamber plate is set to high accuracy (about 10 μm), an ink flow path with little variation can be formed, and good ink ejection characteristics can be obtained. Then, a sufficient amount of adhesive is injected into and fixed to the slight step portion caused by the dimensional difference, so that the tip surface of the convex portion 12 f is bonded to the diaphragm plate 10. The ink chamber plate 27 prevents ink from flowing into the piezoelectric actuator 14 from the common ink chamber 13a of the high-rigidity housing 12, and prevents the piezoelectric element from being broken by conduction between the electrodes of the piezoelectric element 15. Fulfill.

1 is a perspective view illustrating a configuration of an embodiment of an inkjet head according to the present invention. It is sectional drawing which shows the structure of one Example of the inkjet head concerning this invention. It is sectional drawing of the housing part used for the inkjet head concerning this invention. It is a perspective view of the piezoelectric material used for the inkjet head of the present invention. It is explanatory drawing which shows the manufacturing process of the piezoelectric actuator used for this invention inkjet head. It is explanatory drawing which shows the manufacturing process of the piezoelectric actuator used for this invention inkjet head. It is explanatory drawing which shows the manufacturing process of the piezoelectric actuator used for this invention inkjet head. It is explanatory drawing which shows the manufacturing process of the piezoelectric actuator used for this invention inkjet head. FIG. 6 is a characteristic diagram showing the relationship between the number of adjacent nozzles driven and the change in droplet velocity ratio. It is a perspective view which shows the other Example of the highly rigid housing of the inkjet head concerning this invention. 1 is a schematic configuration diagram showing an embodiment of a droplet discharge device using an inkjet head according to the present invention. It is a perspective view which shows the prior art example of the inkjet head using a piezoelectric element. It is a characteristic view showing the relationship between the number of nozzles driven and the deformation ratio of the nozzle plate which is each stacked plate group. It is a characteristic view which shows the relationship between the plate deformation amount and the speed fluctuation rate due to crosstalk.

Explanation of symbols

1: Nozzle 2: Nozzle substrate 3: Channel substrate 4: Pressure chamber 5: Chamber plate 6: Restrictor 7: Restrictor plate 8: Vibration plate 9: Filter unit 10: Diaphragm plate 11: Inkjet head 12: High rigidity housing 12a: Opening portion 12e: Convex portion 12d: Comb-shaped opening groove portion 12f: Comb-shaped convex portion 12i: Connecting member 13: Common ink chamber 14: Piezoelectric actuator 15: Piezoelectric element 16: Fixing member 17: Individual electrode 18: Ink introduction pipe 19: Common electrode 20: Adhesive 21: Internal electrode 22 in contact with both ends of the piezoelectric body 22: External electrode 23: Internal electrode 24 in the center of the piezoelectric body 24: FPC
25: conductive adhesive 26: plate group 27: ink chamber plate 28: recording unit 29: ink cartridge 30: guide shaft 31: recording unit 32: drive source 33: printing medium 34: transport roll 35: opening hole 50: piezoelectric Body 51: Piezoelectric element body

Claims (12)

A nozzle plate having a plurality of nozzle openings for discharging ink droplets, a flow path substrate in which a plurality of pressure chambers corresponding to the nozzle openings are arranged, and a diaphragm plate having a diaphragm formed to seal the pressure chambers A piezoelectric element group disposed so as to sandwich a vibration plate at a position facing the pressure chamber, a housing housing the piezoelectric element group, and an ink chamber plate disposed between the diaphragm plate and the housing The housing has a convex portion on the side in contact with the diaphragm plate, and a comb-shaped opening groove portion into which each of the piezoelectric elements is inserted and a comb-shaped convex portion are formed in the convex portion. In addition, the ink-jet head is characterized in that the ink chamber plate is disposed so as to surround the convex portion . 2. The ink jet head according to claim 1, wherein at least the convex portion of the housing has higher rigidity than the diaphragm plate . 2. The ink chamber plate according to claim 1, wherein the ink chamber plate includes a common ink chamber that supplies ink to each pressure chamber, and is connected to an ink supply path provided in the housing at both ends in the longitudinal direction of the common ink chamber. An inkjet head fixed to the housing . 2. The ink jet head according to claim 1, wherein the pressure chambers arranged in the flow path substrate are arranged so as to face each other around a nozzle row in which a plurality of nozzle openings are arranged in a row . 2. The inkjet head according to claim 1, wherein one end of the piezoelectric element group is formed on the same plane and is bonded to the diaphragm plate, and the other end is fixed to a fixing member . A nozzle plate having a plurality of nozzle openings for discharging ink droplets, a flow path substrate in which a plurality of pressure chambers corresponding to the nozzle openings are arranged, and a diaphragm plate having a diaphragm formed to seal the pressure chambers A piezoelectric element group disposed so as to sandwich a vibration plate at a position facing the pressure chamber, a housing housing the piezoelectric element group, and an ink chamber plate disposed between the diaphragm plate and the housing The housing has a convex portion on the side in contact with the diaphragm plate, and the convex portion includes a comb-shaped opening groove portion into which each of the piezoelectric elements is inserted and a comb-shaped convex portion, An ink jet head comprising a connecting member for connecting comb-shaped convex portions to each other . 7. An ink jet head according to claim 6, wherein a plurality of nozzle rows are provided, and the center of the connecting member is located between the nozzle rows . 7. The ink jet head according to claim 1, wherein a height of the comb-shaped convex portion is made smaller than a thickness of the ink chamber plate . 7. The ink jet head according to claim 1, wherein a height of the comb-shaped convex portion is larger than a depth of the comb-shaped opening groove portion . 7. The ink jet head according to claim 6, wherein the connecting member is provided at a substantially central portion of the comb-shaped opening groove . 7. The ink jet head according to claim 1, wherein a thickness of the comb-shaped convex portion is 60% or more of a thickness in which the nozzle plate, the flow path substrate, the diaphragm plate, and the ink chamber plate are stacked .   A liquid droplet ejection apparatus comprising the ink jet according to claim 1.

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