JP4923815B2 - Inkjet head - Google Patents

Description

  The present invention relates to an ink jet head that transports and ejects a plurality of types of ink from ink supply ports to nozzle holes.

  A piezoelectric inkjet head is laminated on a flow path unit in which a plurality of pressure chambers corresponding to each nozzle hole are provided in a flow path from an ink supply port to a plurality of nozzle holes. And a piezoelectric actuator that selectively varies the volume of the pressure chamber (see, for example, Patent Document 1). The piezoelectric actuator includes a diaphragm, a laminate of piezoelectric layers made of lead zirconate titanate (PZT) or the like formed on the upper surface of the diaphragm, and a plurality of electrodes interposed between the piezoelectric layers. Have. According to such an ink jet head, when a drive voltage is selectively applied to the electrodes of the piezoelectric actuator, an electric field acts on the active portion of the piezoelectric layer sandwiched between the electrodes, causing deformation in the thickness direction. . Then, the deformation of the piezoelectric layer is transmitted to the diaphragm, and the volume of the pressure chamber fluctuates, and ink droplets are ejected from the nozzle holes due to the pressure fluctuation generated in the ink in the pressure chamber.

In addition, when the spread of droplets when landing on a recording medium differs depending on the type of ink, in order to align the dot diameter on the medium, the ejection amount is changed in advance for each ink type, or for recording gradation etc. The ink ejection amount may be changed. Specifically, a plurality of types of sets of pressure chambers and corresponding piezoelectric actuators are arranged with different sizes for each ink ejection amount (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-146968 Japanese Patent Laid-Open No. 9-300612

  However, when the ink discharge amount is adjusted according to the size of the piezoelectric actuator and the pressure chamber, there are a plurality of characteristics in one ink jet head, which makes it difficult to manufacture. Further, if the natural period of ink based on the size of the piezoelectric actuator and the pressure chamber is different for each ink type, it becomes difficult to control each drive and to set the drive period as a whole.

  SUMMARY OF THE INVENTION An object of the present invention is to facilitate manufacture and drive control of an inkjet head that uses a plurality of types of ink, and that uses at least one type of ink ejection amount different from the others.

The present invention has been made in view of the circumstances as described above, and the ink jet head according to the first invention includes the nozzle in the flow path from an ink supply port to a plurality of nozzle holes for each of a plurality of types of ink. A flow path unit provided with a pressure chamber corresponding to each of the holes, and an actuator that is superimposed on the flow path unit and varies the volume of the pressure chamber. The actuator is provided to face each pressure chamber. And at least one surface of a region corresponding to the pressure chamber of the diaphragm, and a plurality of active portions that can be deformed so as to displace portions corresponding to the pressure chambers of the diaphragm. has a deformation and restraint member disposed in a predetermined range so as to restrain the deformation of the diaphragm, leaving a peripheral portion of the region, the area of each of the respective active portions is the same for all types of ink Of the plurality of types of ink, the deformation constraint area of the deformation constraint body corresponding to at least one type of ink with respect to the vibration plate is defined as the deformation constraint area of the deformation constraint body corresponding to another type of ink with respect to the vibration plate. It is characterized by being different.

In this way, when the deformation of the active portion of the actuator is transmitted to the diaphragm, the entire portion where the deformation is restrained by the deformation restraining body of the diaphragm is displaced to change the volume of the pressure chamber. The variable volume of the pressure chamber is proportional to the amount of displacement of the diaphragm and the displacement location area of the diaphragm, but the deformation restraint area of the deformation restraint body with respect to the diaphragm is different from that of other kinds of ink for at least one kind of ink. Therefore, the fluctuating volume of the pressure chamber differs depending on the ink type. Therefore, even if the area of each active part of the actuator is the same for all types of ink, for example, the ejection amount can be changed according to the ink type. Accordingly, it becomes easy to manufacture an ink jet head having a different ink ejection amount from the others, and drive control is facilitated.

  The nozzle hole corresponding to the type of ink having a large deformation restriction area may have a larger hole diameter than the nozzle hole corresponding to the type of ink having a small deformation restriction area.

  In this case, the ink having a large deformation restraint area and a large ejection amount has a large nozzle hole diameter, so that sufficient ejection performance can be obtained.

A deformation constraint area of the diaphragm that is restrained from being deformed by the deformation constraint body may be larger than a pressure receiving area that receives pressure from the active portion in the deformation constraint body.

In this way, deformation restriction area of the diaphragm is constrained deformation by deformation restraint body, since it is larger than the pressure receiving area of the deformation restriction Subjected to pressure from the active portion, the active portion due to the presence of the deformation restriction member An amplification effect can be obtained in which the displacement location area of the diaphragm is larger than the displacement location area. Therefore, even if the displacement amount of the active part of the actuator is small, a large volume fluctuation can be given to the pressure chamber, and the driving efficiency is improved.

An ink jet head according to a second aspect of the invention includes a flow path unit in which a pressure chamber corresponding to each nozzle hole is provided in a flow path from an ink supply port to a plurality of nozzle holes for each of a plurality of types of ink, An actuator stacked on the flow path unit to change the volume of the pressure chamber, and the actuator includes a diaphragm provided facing the pressure chambers, and a portion corresponding to each pressure chamber of the diaphragm. A plurality of active portions that can be deformed so as to be displaced, and at least one surface of the region corresponding to the pressure chamber of the diaphragm, leaving a peripheral portion of the region to restrain deformation of the diaphragm and a deformation restraint member disposed in a predetermined range, the deformation restraint member is deformable restraining area for restraining the deformation of the said diaphragm, and larger than the pressure receiving area for receiving the pressure from the active unit A configuration that, the area of each of the respective active part is the same for all types of ink, the deformation restriction member in response to only some types of inks among the plural types of ink are provided It is characterized by that.

In this way, when the deformation of the active portion of the actuator is transmitted to the diaphragm, the entire portion where the deformation is restrained by the deformation restraining body of the diaphragm is displaced to change the volume of the pressure chamber. The variable volume of the pressure chamber is proportional to the amount of displacement of the diaphragm and the displacement location area of the diaphragm, but the deformation restraint body of the present invention is provided for only some types of ink, so the pressure chamber Will vary depending on the type of ink. Therefore, even if the area of each active part of the actuator is the same for all types of ink, for example, the discharge amount can be changed according to the ink type. Accordingly, it becomes easy to manufacture an ink jet head having a different ink ejection amount from the others, and drive control is facilitated.

  The nozzle hole corresponding to the type of ink provided with the deformation constraint body may have a larger diameter than the nozzle hole corresponding to another type of ink.

  In this case, for the ink having a large amount of ejection provided with the deformation restraining body, sufficient ejection performance can be obtained because the nozzle hole has a large hole diameter.

The deformation constraint body may have a shape in which a bonding area with the diaphragm is larger than a bonding area with the active portion.

In this way, it is possible to easily form a configuration in which the deformation constraint area of the diaphragm that is restrained from being deformed by the deformation constraint body is larger than the pressure receiving area of the deformation constraint body that receives the pressure from the active portion, It becomes possible to improve drive efficiency simply and inexpensively. More specifically, it is preferable that the displacement transmitting body has a convex shape in a cross-sectional view cut in a direction orthogonal to a direction parallel to the diaphragm .

The flow path unit includes a plurality of the pressure chambers arranged in a row with a partition therebetween, and the actuator includes the diaphragm provided continuously over the plurality of pressure chambers, A piezoelectric body provided across the plurality of pressure chambers in parallel to the diaphragm on the opposite side of the pressure chamber of the diaphragm, and the piezoelectric body has a size extending over the plurality of pressure chambers and the vibration A piezoelectric material sheet that is stacked in a direction orthogonal to a direction parallel to the plate, a common electrode that is stacked on the piezoelectric material sheet and continuously disposed corresponding to the plurality of pressure chambers, and the common electrode. A plurality of individual electrodes individually disposed so as to correspond to each of the plurality of pressure chambers with the piezoelectric material sheet interposed therebetween, and the individual electrodes are more than the pressure chambers in a plan view as viewed from the orthogonal direction. Small area, the piezoelectric Is an area corresponding to the individual electrode in the plan view and deformed by an electric field generated between the common electrode and the individual electrode, and an inactive part that is a part other than the active part. The diaphragm is flat in a direction parallel to the diaphragm, and the surface on the diaphragm side is formed flat in the column direction of the pressure chamber, and the inactive portion is interposed between the diaphragm and the piezoelectric body. And a fixed body for connecting the partition wall to each other, and the deformation restricting body may be disposed with a gap between the outer peripheral portion and the fixed body.

In this way, since the deformation restraining member is disposed with a gap with respect to the fixed body that is interposed between the inactive portion and the pressure chamber of the partition walls of the piezoelectric inactive part of the piezoelectric body Even if the active part is connected to the fixed body with a slight shift in assembly, and the active part is positioned with respect to the deformation restraining body, the deformation of the active part can surely deform the diaphragm. Further, when the deformation of the active part of the actuator is transmitted to the deformation restraining body, the diaphragm is deformed together with the deformation restraining body, and the volume of the pressure chamber is changed. Then, regardless of the deformation state of the active portion of the actuator, the deformation restriction area by the deformation restriction body of the diaphragm is stably displaced.

In the piezoelectric surface of the vibration plate side is formed flat in the column direction of the pressure chamber, wherein in the fixed body and the deformation restraint member, the joining surfaces of the piezoelectric body is the diaphragm or al same height There may be.

In this way, the surface of the vibration plate side of the piezoelectric body is formed flat in the column direction of the pressure chamber, and a fixed body and deformed joint surface of the piezoelectric body restraint body vibration plate or al same height Therefore, the laminated structure of the actuator can be easily formed by a flat plate, and the productivity is improved.

The deformation restraining body is provided on a surface of the diaphragm facing the flow path unit, and a displacement transmission body is provided at a position corresponding to the deformation restraining body between the active portion and the vibration plate. together are a second fixed body is provided at a position that overlaps in the plan view and the fixed body between the channel unit and the diaphragm, the displacement transmitting member comprises a second fixed body and the outer peripheral portion It may be arranged over a predetermined range of the diaphragm with a gap between them.

In this case, since the displacement transmitting body is arranged with a gap with respect to the second fixed body, the diaphragm is connected even if the second fixed body is connected to the partition between the pressure chambers with a slight shift in assembly. Is reliably deformed by the required amount without hindering its deformation. Further, when the deformation of the active part of the actuator is transmitted to the displacement transmission body, the diaphragm is also displaced by the movement of the displacement transmission body. At that time, the entire portion of the diaphragm deformed and restrained by the deformation restraining body is displaced, and the volume of the pressure chamber fluctuates. Therefore, even if the displacement amount of the active part of the actuator and the displacement transmitting body is small, stable volume fluctuation can be given to the pressure chamber, and the driving efficiency is improved.

It said displacement transmitting member and the second fixing member may be projected on the diaphragm or al same height.

In this way, since the second fixed body and the displacement transmission member is a diaphragm or al same height, it is possible to easily form a laminated structure of an actuator utilizing a flat plate, the productivity is improved To do.

Bonded area relative to the diaphragm before Symbol deformation restraint member may be larger than the area of the active portion sandwiched between the electrodes corresponding to the deformation restraint member.

In this case, since the joint area of the deformation restraint body with respect to the diaphragm is larger than the active part of the actuator, an amplification effect is obtained in which the displacement part area of the diaphragm is larger than the displacement part area of the actuator. Therefore, even if the displacement amount of the actuator is small, a large volume fluctuation can be given to the pressure chamber, and the driving efficiency is improved.

Note that the volume of each pressure chamber is preferably the same for all types of ink.

  As is apparent from the above description, according to the present invention, it is possible to change the ink ejection amount in accordance with the ink type by the deformation restraining body. Accordingly, it becomes easy to manufacture an ink jet head having a different ink ejection amount from the others, and drive control is facilitated.

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

(First embodiment)
FIG. 1 is an exploded perspective view showing an inkjet head 1 according to the first embodiment of the present invention. As shown in FIG. 1, the inkjet head 1 includes a flow path unit 2 in which a plurality of plates are stacked, and a piezoelectric actuator 3 that is bonded to the flow path unit 2 in an overlapping manner. The flow path unit 2 is configured such that ink is ejected downward from nozzle holes 17a and 17b (see FIG. 3) opened on the lower surface side of the lowermost layer. The actuator 3 includes a piezoelectric body 5 whose required portion is selectively deformed by selectively applying an electric field, and a diaphragm unit 4 disposed on the lower surface of the piezoelectric body 5. A surface electrode 7 is formed on the upper surface of the piezoelectric body 5, and a flexible flat cable 6 for electrical connection with an external device is overlaid. A terminal (not shown) exposed on the lower surface of the flexible flat cable 6 is conductively connected to the surface electrode 7 of the piezoelectric body 5.

  2 is an exploded perspective view of the flow path unit 2 and the diaphragm unit 4 of the inkjet head 1 shown in FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIGS. 2 and 3, the inkjet head 1 has a large number of ink flow paths arranged in five rows, and the right three rows in the figure eject one of cyan, magenta, and yellow color inks. The left two columns are black ink columns BK for ejecting black ink.

  FIG. 4 is an enlarged view of the main part showing the second black ink row BK and the third color ink row CL from the left side of FIG. As shown in FIGS. 2 and 4, the flow path unit 2 includes a pressure chamber plate 10, a first connection flow path plate 11, a second connection flow path plate 12, a first manifold plate 13, and a second manifold. The plate 14, the damper plate 15, the cover plate 16, and the nozzle plate 17 are each bonded and laminated. The nozzle plate 17 is a resin sheet such as polyimide, and the other plates 10 to 16 are metal plates such as 42% nickel alloy steel plate (42 alloy), each having a thickness of about 50 to 150 μm. Each of the plates 10 to 17 is formed with an opening or a recess that constitutes a flow path by electrolytic etching, laser processing, plasma jet processing, or the like.

  As shown in FIG. 2, the pressure chamber plate 10 has a large number of pressure chamber holes 10a arranged in five rows along the long side, and an ink supply port (liquid inflow port) 10c. Is configured. The pressure chamber hole 10a has an oval shape having a long axis in a direction orthogonal to the column direction in plan view (see FIG. 5). What is the pressure chamber hole adjacent to the column direction and the direction orthogonal thereto? It is separated by a partition wall 10b.

  As shown in FIGS. 2 and 4, the first connection flow path plate 11 has a communication hole 11 a that communicates with the end of the pressure chamber hole 10 a and an outflow that communicates with the opposite end of the pressure chamber hole 10 a. It has a through hole 11b and an ink supply port 11c that communicates with the ink supply port 10c in the same shape. The second connection flow path plate 12 has one end communicating with the communication hole 11a and a recess 12a formed along the longitudinal direction of the pressure chamber hole 10a, and a communication hole 12b formed at the other end of the recess 12a. An outflow through hole 12c communicating with the outflow through hole 11b and an ink supply port 12d communicating with the ink supply port 11c in the same shape are provided. The first connection flow path plate 11 and the second connection flow path plate 12 constitute a connection flow path layer.

  The first manifold plate 13 includes a first manifold hole 13a extending in the row direction below the pressure chamber holes 10a so as to communicate with each row of the pressure chamber holes 10a via the communication holes 12b, and an outflow through hole. 12c, and an outflow through hole 13b communicating with each of 12c. The second manifold plate 14 has a second manifold hole 14a that communicates with the first manifold hole 13a, and an outflow through hole 14b that communicates with the outflow through hole 13b. The first manifold plate 13 and the second manifold plate 14 constitute a manifold layer.

  The damper plate 15 includes a damper wall 15a that is thinned by forming a recess from the side opposite to the manifold hole 14a, and an outflow through hole 15c that communicates with the outflow through hole 14b to form a damper layer. is doing. That is, as shown in FIG. 4, the damper layer has a gap 15b formed on the opposite side of the manifold hole 14a with each damper wall 15a as a boundary. The cover plate 16 has an outflow through hole 16a communicating with the outflow through hole 15c. The nozzle plate 17 has nozzle holes (liquid outlets) 17a and 17b that communicate with the outflow through hole 16a and eject ink to the outside. However, the nozzle hole 17b of the black ink row BK has a larger diameter than the nozzle hole 17a of the color ink row CL.

As shown in FIG. 4, the actuator 5 includes a large number of piezoelectric material sheets 22 to 28 made of a lead zirconate titanate (PZT) ceramic material having a thickness of about 30 μm, and an insulating top. Sheets 29 are laminated. The piezoelectric material sheets 22 to 28 are flat in a direction parallel to the diaphragm 19 and are laminated in a direction orthogonal to the parallel direction. The piezoelectric material sheets 22 to 26 are continuously arranged on the upper surfaces of the odd-numbered piezoelectric material sheets 22, 24, 26 counted from the lowermost piezoelectric material sheet 22 in correspondence with the large number of pressure chamber holes 10 a. The common electrode 30 is printed. A large number of piezoelectric material sheets 22 to 26 are arranged on the upper surface of the even-numbered piezoelectric material sheets 23 and 25 from the lowest piezoelectric material sheet 22 so as to correspond to the respective pressure chamber holes 10a. The individual electrodes 31 are printed in five rows. In the piezoelectric body 5, the deformable part corresponding to the individual electrode 31 is the active part A 1, and the other part is the inactive part A 2. The individual electrodes 31 are common to both the black ink row BK and the color ink row CL, and have the same area in plan view. Further, the common electrode 30 and the individual electrode 31 are provided on the top layer of the uppermost layer via relay conductors (not shown) provided on the side end surfaces of the piezoelectric material sheets 22 to 28 and the top sheet 29 or through holes (not shown). The sheet 29 is electrically connected to the surface electrode 7 (see FIG. 1) on the upper surface.

  The diaphragm unit 4 includes a diaphragm 19 made of a flat resin sheet such as polyimide having a thickness of about 20 to 50 μm, and 42% nickel having a thickness of about 50 to 150 μm bonded to the upper surface of the diaphragm 19. And an intermediate plate 20 using a metal plate such as an alloy steel plate (alloy 42). In addition, as shown in FIG. 2, the diaphragm unit 4 has the same outer shape as the flow path unit 2 in plan view, and has ink supply ports 19a and 20d at positions corresponding to the ink supply ports 10c of the pressure chamber plate 10. The ink supply ports 19a and 20d are covered with a filter 21 for removing dust mixed in ink supplied from an ink tank (not shown).

  FIG. 5 is an exploded perspective view of the main part including the diaphragm unit 4 of the inkjet head 1 shown in FIG. FIG. 6 is a principal plan view for explaining the arrangement of the deformation restraining bodies 37 and 38 of the diaphragm unit 4 of the inkjet head 1 shown in FIG. As shown in FIGS. 4 to 6, the intermediate plate 20 includes deformation restraints 37 and 38 surrounded by annular gaps 20 a and 20 b along the outer periphery of the pressure chamber hole 10 a in a plan view, and non-piezoelectric members 5. A fixed body 20c that connects the active part A2 to the partition wall 10b of the pressure chamber plate 10 via the diaphragm 19 is provided. The fixed body 20c has a shape that substantially matches the partition wall 10b surrounding the pressure chamber hole in plan view. The deformation restriction bodies 37 and 38 are oval-shaped deformation restriction parts 37b and 38b that are accommodated in the pressure chamber hole 10a in a plan view, and the deformation restriction parts in a plan view that protrudes upward from the deformation restriction parts 37b and 38b. Pressure receiving portions 37a and 38a having an oval shape that are accommodated inside 37b and 38b. That is, as shown in FIG. 4, the deformation restraining bodies 37 and 38 have a convex shape in a cross-sectional view, and from the joint area S <b> 1 (pressure receiving area) between the pressure receiving portions 37 a and 38 a and the active portion A <b> 1 of the piezoelectric body 5. In addition, the joining areas S2 and S3 (deformation restraining areas) between the deformation restraining portions 37b and 38b and the diaphragm 19 are large. In other words, the bonding area S1 of the pressure receiving portions 37a, 38a of the deformation restraining bodies 37, 38 to the piezoelectric body 5 is the same as the area S1 of the active portion, that is, the individual electrode 31, while the deformation restraining bodies 37, 38 are deformed. The joint areas S2 and S3 of the restraining bodies 37 and 38 with respect to the diaphragm 19 of the deformation restraining portions 37b and 38b are larger than the area S1 of the active portion corresponding to the deformation restraining body 37, that is, the individual electrode 31.

  Further, the joining area S3 of the deformation restraining portion 38b of the deformation restraining body 38 of the black ink row BK to the vibration plate 19 is larger than the joining area S2 of the deformation restraining portion 37b of the deformation restraining body 37 of the color ink row CL to the vibration plate 19. It has become big. However, the bonding area S1 of the pressure receiving portion 38a of the deformation restraining body 38 of the black ink row to the piezoelectric body 5 is the same as the bonding area S1 of the pressure receiving portion 37a of the deformation restraining body 37 of the color ink row CL to the piezoelectric body 5. is there. Further, the fixed body 20c and the deformation restraining bodies 37 and 38 are such that the intermediate plate 20 and the diaphragm 19 are bonded together, and the intermediate plate 20 is etched to remove portions corresponding to the gaps 20a and 20b. Made with. Therefore, the joint surfaces of the fixed body 20 b and the deformation restraining bodies 37 and 38 with the piezoelectric body 5 are substantially at the same height from the diaphragm 19. The deformation constraint bodies 37 and 38 only have to be higher in material or structural rigidity than the diaphragm 19. For example, the deformation constraint body and the diaphragm are made of the same material and the deformation constraint body has a honeycomb structure in plan view. It may be possible to increase the rigidity. Further, the thicknesses of the pressure receiving portions 37a and 38a and the deformation restraining portions 37b and 38b are not particularly limited, but are the same in the present embodiment.

  When the diaphragm unit 4 is inserted between the flow path unit 2 and the piezoelectric body 5, the diaphragm unit 4 is first bonded to the piezoelectric body 5 to form the actuator 3. At this time, since the upper surfaces of the deformation restraining bodies 37 and 38 of the diaphragm unit 4 and the fixed body 20c are at the same height and the lower surface of the piezoelectric body 5 is flat, the diaphragm is interposed by inserting an adhesive therebetween. The unit 4 and the piezoelectric body 5 can be securely bonded by sandwiching and pressing the unit 4 and the piezoelectric body 5 from above and below with flat jigs. In addition, it is desirable that the active portion of the piezoelectric body 5 and the displacement transmitting bodies 37 and 38 correspond exactly, but even if they are slightly displaced in the assembly, the deformation restraining body 37 via the gaps 20a and 20b with respect to the fixed body 20c. 38 are accurately secured, the displacement of the diaphragm 19 with respect to the pressure chamber 35 is sufficiently secured. Then, the actuator 3 composed of the diaphragm unit 4 and the piezoelectric body 5 is bonded to the flow path unit 2 in which a plurality of plates are laminated and fixed in advance.

  Next, the ink flow path in the flow path unit 2 will be described with reference to FIG. The common liquid chamber 33 communicating with the ink supply ports 10c, 11c, 12d, 19a, and 20d (see FIG. 2) closes the upper and lower sides of the manifold holes 13a and 14a with the second connection flow path plate 12 and the damper plate 15. It is formed with. The common liquid chamber 33 extends in the row direction so as to overlap a pressure chamber 35 described later in plan view. The lower surface of the common liquid chamber 33 is formed by a damper wall 15a having substantially the same shape as the common liquid chamber 33 in plan view. The gap 15b located on the opposite side of the common liquid chamber 33 with the damper wall 15a as a boundary is sealed by the lower side being closed by the cover plate 16.

  The common liquid chamber 33 communicates with one end of a pressure chamber 35 located above via a crank-shaped connection flow path 34. The connection flow path 34 is formed by the communication hole 11a of the first connection flow path plate 11, the recess 12a of the second connection flow path plate 12, and the communication hole 12b. The connection channel 34 has a constricted portion 34 a that has the largest channel resistance with the narrowest channel cross-sectional area among the channels from the common liquid chamber 33 to the pressure chamber 35. The pressure chamber 35 is formed by closing the upper and lower sides of the pressure chamber hole 10 a with the diaphragm 19 and the first connection flow path plate 11. An outflow passage 36 communicates with the other end of the pressure chamber 35. The outflow passage 36 is formed by the outflow through holes 11b, 12c, 13b, 14b, 15c, 16a, 17a, and 17b, and gradually decreases in diameter toward the lower nozzle holes 17a and 17b. (Direction perpendicular to the plate surface).

  Next, the operation of the inkjet head 1 will be described. FIG. 7 is an enlarged view of a main part for explaining the ink ejection operation of the ink jet head shown in FIG. As shown in FIG. 7, a voltage is selectively applied to the individual electrode 31 of the piezoelectric body 5 to generate a potential difference with the common electrode 30, so that the electrodes 30 and 31 of the piezoelectric material sheets 23 to 26 are connected. An electric field acts on the active part A1 positioned to cause distortion in the stacking direction. When the deformation of the active portion A1 is transmitted to the pressure receiving portions 37a and 38a of the deformation restraining bodies 37 and 38, the deformation restraining bodies 37 and 38 are displaced downward, and the deformation restraining portions 37b and 38b press the diaphragm 19. To deform. A pressure is applied to the ink in the pressure chamber 35 by the deformation of the vibration plate 19, and the ink is ejected from the nozzle holes 17 a and 17 b through the outflow path 36.

  At this time, the fluctuating volume of the pressure chamber 35 is proportional to the downward displacement amount of the diaphragm 19 and the displacement location area of the diaphragm 19, but the deformation restraint area of the deformation restraining body 38 of the black ink row BK with respect to the diaphragm 19 Since S3 is larger than the deformation restraining area S2 of the deformation restraining body 37 of the color ink row CL with respect to the diaphragm 19, the variation volume of the pressure chamber 35 is larger in the black ink row BK than in the color ink row CL. Therefore, even if the deformation areas of the respective active portions A1 of the piezoelectric body 5 are the same for all types of ink, it is possible to increase the amount of black ink ejected more than the amount of color ink ejected. A plurality of types of inkjet heads 1 can be easily formed with the piezoelectric body 5.

  For example, when pigment ink is used as the black ink and dye ink is used as the color ink, the pigment ink is difficult to spread on the recording medium, so the ejection amount per droplet is the same for the black ink and the color ink. Then, the black ink has a smaller dot diameter on the recording medium than the color ink. In the above-described embodiment, the amount of ejection is increased by increasing the volume fluctuation of the black ink in the pressure chamber and increasing the nozzle diameter so that the dot diameters of both are substantially the same. The dot diameter on the recording medium may be positively varied.

  Further, since the area of the active portion and the volume of the pressure chamber are the same for the black ink and the color ink, the natural frequency of the ink in the pressure chamber is almost the same. As a result, the pulse width and voltage value of the voltage waveform signal applied to the electrodes can be set to be substantially the same, and the driving cycle of the entire apparatus can be easily set.

  Further, the diaphragm is restrained from being deformed by the deformation restraining portions 37b and 38b of the deformation restraining bodies 37 and 38, rather than the pressure receiving area S1 of the pressure receiving portions 37a and 38a of the deformation restraining bodies 37 and 38 that receive the pressure from the active part A1. Since the deformation restraining areas S2 and S3 of 19 are large, an amplification effect that makes the displacement part area of the diaphragm 19 larger than the displacement part area of the active part A1 is obtained. Therefore, even if the displacement area in plan view of the active portion A1 of the piezoelectric body 5 of the actuator 3 is small, a large volume fluctuation can be given to the pressure chamber 35, and the driving efficiency is improved. In addition, even if the area of the active portion A1 is reduced, sufficient volume fluctuations can be given to the pressure chamber 35. Therefore, the capacitance of the piezoelectric material sheets 22 to 28 can be reduced to reduce power consumption. In addition, the amount of heat generated by the actuator 3 can be suppressed.

  In the present embodiment, the deformation restraining body 37 is integrally formed, but the pressure receiving portion 37a and the deformation restraining portion 37b may be formed separately. Further, in the present embodiment, the bonding area S1 between the pressure receiving portion 37a of the deformation constraint body 37 and the piezoelectric body 5 is the same as the pressure reception area, but by making the deformation constraint body like a honeycomb structure in a plan view, The pressure receiving area may be larger than the bonding area. Similarly, the joining area S2 between the deformation restraining portion 37b of the deformation restraining body 37 and the vibration plate 19 is the same as the deformation restraining area. However, by making the deformation restraining body into a honeycomb structure in a plan view, for example, The deformation constraint area may be larger than the area.

(Second Embodiment)
FIG. 8 is a cross-sectional view of a main part of the inkjet head 40 of the second embodiment. In addition, about the part which is common in 1st Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. As shown in FIG. 8, the diaphragm unit 41 has a diaphragm 19 made of a resin sheet such as polyimide having a thickness of about 20 to 50 μm, and a thickness of 50 to 150 μm bonded to the upper surface of the diaphragm 19. A 42% nickel alloy steel plate having a thickness of about 30 to 100 μm and a first intermediate plate 42 in which a metal plate such as a 42% nickel alloy steel plate (42 alloy) is used, and being adhered to the lower surface of the diaphragm 19. A second intermediate plate 43 using a metal plate such as (42 alloy) is provided.

  The first intermediate plate 42 includes a displacement transmission body 44 surrounded by an annular gap 42a along the outer periphery of the pressure chamber hole 10a in plan view, and the inactive portion A2 of the piezoelectric body 5 as the vibration plate 19 and the second intermediate plate. And a fixed body 42 b connected to the partition wall 10 b of the pressure chamber plate 10 through 43. The displacement transmission body 44 has a flat long cylindrical shape that is accommodated in the pressure chamber hole 10 a in plan view, and is bonded to the active area A 1 of the piezoelectric body 5 (pressure receiving area) and the vibration plate 19. The area S1 is substantially the same. The displacement transmission bodies 44 used for both the black ink row BK and the color ink row CL are the same.

  The second intermediate plate 43 includes the deformation restraining bodies 45 and 46 surrounded by annular gaps 43a and 43b along the outer periphery of the pressure chamber hole 10a in plan view, and the inactive portion A2 of the piezoelectric body 5 through the diaphragm 19. And a second fixed body 43 c connected to the partition wall 10 b of the pressure chamber plate 10. The deformation restraining bodies 45 and 46 have a flat long cylindrical shape that fits inside the pressure chamber hole 10a in plan view, and have a larger area than the displacement transmission body 44 in plan view. That is, the bonding areas S2 and S3 (deformation constraint area) of the deformation restrainers 45 and 46 with the diaphragm 19 are larger than the junction area S1 (pressure receiving area) of the displacement transmission body 44 with the active portion A1 of the piezoelectric body 5. Has a large configuration. In other words, the bonding area S1 of the displacement transmission body 44 with respect to the piezoelectric body 5 is the same as the area of the active portion corresponding to the displacement transmission body 44, that is, the individual electrode 31, while the diaphragm 19 of the deformation restraining bodies 45 and 46. Are larger than the areas of the active portions corresponding to the deformation restrainers 45, 46, that is, the individual electrodes 31, respectively.

  Further, the bonding area S3 of the deformation constraint body 46 of the black ink row BK to the vibration plate 19 is larger than the bonding area S2 of the deformation constraint body 45 of the color ink row CL to the vibration plate 19. Further, in a state where the intermediate plates 42 and 43 and the vibration plate 19 are bonded, the intermediate plates 42 and 43 are etched in the same manner as in the above-described embodiment, so that the fixed bodies 42b and 43c, the displacement transmission body 44, the deformation constraint The bodies 45 and 46 are created. For this reason, the deformation restraining bodies 45 and 46 and the second fixed body 43c protrude downward from the diaphragm 19 at substantially the same height. Further, the fixed bodies 42b and 43c have a shape that substantially matches the partition wall 10b surrounding the pressure chamber hole 10a in plan view.

  Further, the pressure chamber hole 10 a of the pressure chamber plate 10 is closed above the diaphragm 19 and the deformation restraining bodies 45 and 46, and the pressure chamber hole 10 a is closed below the first connection flow path plate 11 to Pressure chambers 46 and 47 are formed in the chamber hole 10a and the gaps 43a and 43b. The deformation constraint bodies 45 and 46 only have to be higher in material or structural rigidity than the diaphragm 19. For example, the deformation constraint body and the diaphragm are made of the same material, and the deformation constraint body has a honeycomb structure in plan view. It may be possible to increase the rigidity.

  As in the previous embodiment, the diaphragm unit 41 is bonded to the piezoelectric body 5 to form an actuator 49. At this time, the upper surfaces of the displacement transmitting body 44 and the fixed body 42b of the diaphragm unit 41 are at the same height, the lower surfaces of the deformation restraining body 45 and the fixed body 43c are at the same height, and the lower surface of the piezoelectric body 5 is flat. Therefore, the diaphragm unit 4 and the piezoelectric body 5 can be securely bonded by sandwiching and pressing the diaphragm unit 4 and the piezoelectric body 5 from above and below with flat jigs.

  Then, an actuator 49 composed of the diaphragm unit 41 and the piezoelectric body 5 is bonded to the flow path unit 2 in which a plurality of plates are stacked and fixed in advance. Even if the active portion of the piezoelectric body 5 and the displacement transmission body 44 are slightly deviated from each other, the amount of displacement of the diaphragm 19 is ensured as in the above embodiment. Furthermore, even if the fixed body 43c is bonded to the partition wall 10b of the flow path unit with a slight shift, the position of the deformation restraining body 45 is accurately secured to the fixed body 43c via the gap 43a. The 19 displacement is not disturbed.

  Next, the operation of the inkjet head 40 will be described. As shown in FIG. 8, the deformation constraint area S3 of the deformation constraint body 46 of the black ink column BK with respect to the diaphragm 19 is larger than the deformation constraint area S2 of the deformation constraint body 45 of the color ink column CL with respect to the diaphragm 19. The pressure chamber 48 of the black ink row BK has a larger fluctuation volume than the pressure chamber 47 of the color ink row CL. Therefore, even if the deformation area of each active portion A1 of the piezoelectric body 5 is the same for all types of ink, the discharge amount of black ink can be made larger than the discharge amount of color ink.

  Further, the deformation restraining areas S2 and S3 of the diaphragm 19 whose deformation is restrained by the deformation restraining bodies 45 and 46 are larger than the pressure receiving area S1 of the displacement transmitting body 44 that receives the pressure from the active portion A1 of the piezoelectric body 5. Therefore, an amplification effect can be obtained that makes the displacement part area of the diaphragm 19 larger than the displacement part area of the active part A1. Therefore, even if the displacement area of the active portion A1 of the piezoelectric body 5 of the actuator 49 is small, a large volume fluctuation can be given to the pressure chambers 47 and 48, and the driving efficiency is improved. In addition, even if the area of the active part A1 is reduced, sufficient volume fluctuations can be given to the pressure chambers 47 and 48. Therefore, it is possible to reduce the electrostatic capacity of the actuator 49 and suppress the heat generation amount. .

(Third embodiment)
FIG. 9 is a cross-sectional view of a main part of an inkjet head 50 according to the third embodiment. In addition, about the part which is common in 1st Embodiment or 2nd Embodiment, the same code | symbol is attached | subjected and the following description is abbreviate | omitted. As shown in FIG. 9, the diaphragm unit 51 includes a diaphragm 19, a first intermediate plate 20 that is bonded to the upper surface of the diaphragm 19, and a second intermediate that is bonded to the lower surface of the diaphragm 19. A plate 43 is provided. That is, the first intermediate plate 20 is the same as that of the first embodiment, and the second intermediate plate 43 is the same as that of the second embodiment.

  The deformation restraining bodies 37 and 38 formed on the first intermediate plate 20 have a convex shape in a cross-sectional view, and a bonding area S1 (pressure receiving area) between the pressure receiving portions 37a and 38a and the active portion A1 of the piezoelectric body 5. In addition, the joint areas S2 and S3 (deformation restraint areas) between the deformation restraint portions 37b and 38b and the diaphragm 19 are larger. Further, the deformation restriction area S3 of the vibration plate 19 by the deformation restriction portion 38b of the deformation restriction member 38 of the black ink row BK is the deformation restriction area S2 of the vibration plate 19 by the deformation restriction portion 37b of the deformation restriction member 37 of the color ink row CL. It has become bigger.

  The deformation constraint bodies 45 and 46 formed on the second intermediate plate 43 have a long cylindrical shape, and the bonding areas S2 and S3 (deformation constraint areas) with the vibration plate 19 are vibration plates 19 of the deformation constraint bodies 37 and 38. Are substantially the same as the bonding areas S2 and S3. In other words, the deformation restraining bodies 45 and 46 are provided at positions substantially overlapping with the deformation restraining portions 37b and 38b of the deformation restraining bodies 37 and 38 in plan view.

  Next, the operation of the inkjet head 50 will be described. As shown in FIG. 9, the deformation constraint area S3 of the deformation constraint bodies 38 and 46 of the black ink row BK with respect to the diaphragm 19 is greater than the deformation constraint area S2 of the deformation constraint bodies 37 and 45 of the color ink row CL with respect to the vibration plate 19. Therefore, the pressure volume of the pressure chamber 48 of the black ink row BK is larger than that of the pressure chamber 47 of the color ink row CL. Therefore, even if the deformation area of each active portion A1 of the piezoelectric body 5 is the same for all types of ink, the discharge amount of black ink can be made larger than the discharge amount of color ink.

  Further, the deformation restraining portions 37b and 38b of the deformation restraining bodies 37 and 38 and the deformation restraining body are larger than the pressure receiving area S1 of the pressure receiving portions 37a and 38a of the deformation restraining bodies 37 and 38 that receive the pressure from the active portion A1 of the piezoelectric body 5. Since the deformation restraining areas S2 and S3 of the diaphragm 19 constraining deformation by 45 and 46 are large, an amplification effect is obtained in which the displacement part area of the diaphragm 19 is made larger than the displacement part area of the active part A1. At this time, since the deformation of the diaphragm 19 is constrained from above and below, the deformation constraining effect can be obtained more stably.

  As described above, even if the displacement amount of the active portion A1 of the piezoelectric body 5 of the actuator 52 is small, a large volume fluctuation can be given to the pressure chambers 47 and 48, and the driving efficiency is improved. In addition, even if the area of the active portion A1 is reduced, sufficient volume fluctuations can be given to the pressure chambers 47 and 48. Therefore, the capacitance of the actuator 52 can be reduced and the amount of generated heat can be suppressed. .

  Next, an example of use of the inkjet head of the present invention in an inkjet printer will be described. FIG. 10 is a plan view for explaining an example of use of the inkjet head of the present invention. As shown in FIG. 10, in this usage example, the two inkjet heads 100 and 200 are arranged side by side in a direction orthogonal to the row direction of the pressure chambers 35. Note that the configuration of the inkjet heads 100 and 200 is the same as that of the first embodiment described above except that the pressure chambers 35 are not in 5 rows but 4 rows, and thus detailed description thereof is omitted.

  In the inkjet head 100 on the left side in the drawing, the pressure chambers 35 in the left two rows are for black ink, and the pressure chambers 35 in the right two rows are for cyan ink. In the right side inkjet head 200 in the figure, the left two rows of pressure chambers 35 are for magenta ink, and the right two rows of pressure chambers 35 are for yellow ink. The deformation constraint body 38 having a large deformation constraint area is used for the black ink row BK, and the deformation constraint body 37 having a small deformation constraint area is used for the cyan ink row C, the magenta ink row M, and the yellow ink row Y. It has been.

  With the above configuration, the piezoelectric body (not shown) stacked on the upper surface of the vibration plate units 101 and 201 of the inkjet heads 100 and 200 has a deformation amount common to all the ink rows BK, C, M, and Y. Even if it has an active portion, the ink discharge amount of the black ink row BK can be made larger than that of the other ink rows C, M, and Y. Thus, while sharing the pattern of the active portion of the piezoelectric body, the positional relationship between the ink rows BK, C, M, and Y, that is, for each ink type, can be changed only by appropriately changing the arrangement of the deformation constraint bodies 37 and 38. The positional relationship of the nozzle holes can be easily changed. Therefore, as shown in FIG. 10, the same kind of ink rows are arranged adjacent to each other, and the positions of the nozzle holes of the same kind of ink can be easily arranged close to each other.

  As described above, the ink jet head according to the present invention has an excellent effect of improving the degree of freedom in nozzle arrangement design, and is beneficial when applied to an ink jet printer or the like.

1 is an exploded perspective view showing an inkjet head according to a first embodiment of the present invention. It is a disassembled perspective view of the flow path unit and diaphragm unit of the inkjet head shown in FIG. It is the III-III sectional view taken on the line of FIG. It is a principal part enlarged view of FIG. It is a principal part disassembled perspective view containing the diaphragm unit of the inkjet head shown in FIG. It is a principal part top view explaining arrangement | positioning of the deformation | transformation restraint body of the inkjet head shown in FIG. It is drawing explaining the ink ejection operation | movement of the inkjet head shown in FIG. It is principal part sectional drawing of the inkjet head of 2nd Embodiment. It is principal part sectional drawing of the inkjet head of 3rd Embodiment. It is a top view explaining the usage example of the inkjet head of this invention.

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3, 49, 52 Actuator 4, 41, 51 Diaphragm unit 5 Piezoelectric body 10b Partition 10c, 11c, 12d, 19a, 20d Ink supply port 17a, 17b Nozzle hole 19 Diaphragm 20b, 42b fixation Body 22 to 28 Piezoelectric material sheet 30 Common electrode 31 Individual electrodes 35, 47, 48 Pressure chambers 37, 38, 45 Deformation restraining body 43c Second fixed body 44 Displacement transmission body A1 Active part A2 Inactive part S1 Pressure receiving area S2, S3 Deformation constraint area

Claims (13)

For each of a plurality of types of ink, a flow path unit in which a pressure chamber corresponding to each of the nozzle holes is provided in a flow path from the ink supply port to the plurality of nozzle holes; An actuator that varies the volume,
The actuator includes a diaphragm provided facing the pressure chambers, a plurality of active portions that can be deformed to displace portions corresponding to the pressure chambers of the diaphragm, and the vibration plate A deformation restraint body disposed in a predetermined range so as to restrain the deformation of the diaphragm, leaving a peripheral portion of the region on at least one surface of the region corresponding to the pressure chamber,
The area of each active part is the same for all types of ink,
Of the plurality of types of ink, the deformation constraint area of the deformation constraint body corresponding to at least one type of ink with respect to the vibration plate is defined as the deformation constraint area of the deformation constraint body corresponding to another type of ink with respect to the vibration plate. An inkjet head characterized by being different from the above.   2. The inkjet head according to claim 1, wherein the nozzle hole corresponding to the type of ink having a large deformation restriction area has a larger hole diameter than the nozzle hole corresponding to the type of ink having a small deformation restriction area. .   3. The inkjet according to claim 1, wherein a deformation constraining area of the diaphragm that is restrained from being deformed by the deformation constraining body is larger than a pressure receiving area that receives pressure from the active portion in the deformation constraining body. head. For each of a plurality of types of ink, a flow path unit in which a pressure chamber corresponding to each of the nozzle holes is provided in a flow path from the ink supply port to the plurality of nozzle holes; An actuator that varies the volume,
The actuator includes a diaphragm provided facing the pressure chambers, a plurality of active portions that can be deformed to displace portions corresponding to the pressure chambers of the diaphragm, and the vibration plate A deformation restraint body disposed in a predetermined range so as to restrain the deformation of the diaphragm, leaving a peripheral portion of the region on at least one surface of the region corresponding to the pressure chamber,
The deformation constraint body has a configuration in which a deformation constraint area that restrains deformation of the diaphragm is larger than a pressure receiving area that receives pressure from the active part,
The area of each active part is the same for all types of ink,
An ink jet head, wherein the deformation restraining body is provided corresponding to only some types of ink among the plurality of types of ink.   The inkjet head according to claim 4, wherein the nozzle hole corresponding to the type of ink provided with the deformation constraint body has a larger hole diameter than the nozzle hole corresponding to another type of ink.   The inkjet head according to claim 3, wherein the deformation restraining body has a shape in which a bonding area with the diaphragm is larger than a bonding area with the active portion. The inkjet head according to claim 6, wherein the displacement transmission body has a convex shape in a cross-sectional view cut in a direction orthogonal to a direction parallel to the diaphragm . The flow path unit has a plurality of the pressure chambers arranged in a row with a partition interposed therebetween,
The actuator includes the diaphragm provided continuously over the plurality of pressure chambers, and a piezoelectric body provided over the plurality of pressure chambers in parallel with the diaphragm on the opposite side of the pressure chamber from the pressure chambers. Have
The piezoelectric body corresponds to the plurality of pressure chambers, the piezoelectric material sheet having a size extending over the plurality of pressure chambers and stacked in a direction perpendicular to a direction parallel to the diaphragm, and being stacked on the piezoelectric material sheet. And the plurality of individual electrodes individually arranged so as to correspond to each of the plurality of pressure chambers with the piezoelectric material sheet sandwiched between the common electrodes. The electrode has a smaller area than the pressure chamber in a plan view seen from the orthogonal direction,
The piezoelectric body is an area corresponding to the individual electrode in the plan view, the active part deformed by an electric field generated between the common electrode and the individual electrode, and an inactive part other than the active part And a flat surface in the direction parallel to the diaphragm, and the surface on the diaphragm side is formed flat in the column direction of the pressure chambers,
A fixed body that connects the inactive portion and the partition wall is interposed between the diaphragm and the piezoelectric body, and the deformation constraint body has a gap between the outer peripheral portion and the fixed body. The inkjet head according to claim 1, wherein the inkjet head is disposed.   The ink jet head according to claim 8, wherein the fixed body and the deformation restraint body have joint surfaces with the piezoelectric body at the same height from the diaphragm. The deformation restraining body is provided on a surface of the diaphragm facing the flow path unit, and a displacement transmission body is provided at a position corresponding to the deformation restraining body between the active portion and the vibration plate. And a second fixed body is provided at a position overlapping the fixed body in the plan view between the diaphragm and the flow path unit,
The inkjet head according to claim 8 or 9, wherein the displacement transmitting body is disposed over a predetermined range of the diaphragm with a gap between an outer peripheral portion thereof and the second fixed body.   The inkjet head according to claim 10, wherein the displacement transmission body and the second fixed body protrude at the same height from the diaphragm.   The inkjet head according to claim 11, wherein a bonding area of the deformation constraint body with respect to the diaphragm is larger than an area of an active portion sandwiched between the electrodes corresponding to the deformation constraint body.   The inkjet head according to claim 1, wherein the volume of each pressure chamber is the same for all types of ink.

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