JP2008149662A - Piezoelectric/electrostrictive actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric/electrostrictive actuator which increases an excluded volume of an individual liquid chamber, achieves high densification of a head, and further reduces excessive load on interfaces between a substrate and a diaphragm at both lengthwise front and rear edges of the diaphragm, or on a fringe portion when the individual liquid chamber and the diaphragm are formed of the substrate in one body, due to deformability of a piezoelectric/electrostrictive element in an individual liquid chamber widthwise direction more largely than in an individual liquid chamber lengthwise direction, to thereby eliminate leakage of ink from the individual liquid chamber due to separation or breakage, and improve the durability of the actuator. <P>SOLUTION: According to the configuration of the piezoelectric/electrostrictive actuator, the piezoelectric/electrostrictive element is formed of a lower electrode, a piezoelectric/electrostrictive body, and an upper electrode which are formed on the diaphragm fixed to the substrate in every direction and having a different aspect ratio. Then at least one of the lower electrode, the piezoelectric/electrostrictive body, and the upper electrode of the piezoelectric/electrostrictive element is arranged like a comb-like shape having a plurality of comb teeth at right angles to or at an angle with respect to a lengthwise direction of the diaphragm. Then the piezoelectric/electrostrictive actuator is employed in an on-demand ink-jet printer head. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric / electrostrictive actuator used in a scanner such as a head for an inkjet printer, an ultrasonic motor, or a micromirror device, and in particular, drops are intermittently applied to a recording material according to an image. The present invention relates to a piezoelectric / electrostrictive actuator used in an on-demand type recording head that performs recording on a recording material by discharging.

  As a recording head used in an on-demand type ink jet printer that has been commercialized for office, home use, or business use, two methods, a thermal method and a piezoelectric / electrostrictive method, have become mainstream.

  The thermal on-demand type ink jet head includes a discharge port provided for discharging a liquid, and a heat acting part that communicates with the discharge port and is a portion where thermal energy for discharging droplets acts on the liquid. The liquid discharge part which has the liquid flow path which makes a part of a structure, and the electrothermal conversion body as a means to generate | occur | produce a thermal energy are comprised.

  The electrothermal transducer includes a pair of electrodes, and a heating resistor layer connected to the electrodes and having a region (heat generating portion) that generates heat between the electrodes.

  A typical example showing the structure of such an ink jet head is shown in FIGS. 11 (a) and 11 (b).

  FIG. 11A is a partial front view as seen from the discharge port side of a typical ink jet head, and FIG. 11B is a partial cross-sectional view when cut along a portion indicated by a one-dot chain line XY in 11A. It is.

  The recording head 301 shown in FIG. 11 is a groove in which a predetermined number of grooves with a predetermined linear density and a predetermined width and depth are provided on the surface of a substrate 303 on which an electrothermal transducer 302 is provided. The discharge port 305 and the liquid discharge part 306 are formed by bonding so as to cover the attached plate 304.

  The recording head shown in FIG. 11 is shown as having a plurality of discharge ports 305.

  The liquid discharge unit 306 has a discharge port 305 for discharging liquid at the end thereof, and heat energy generated by the electrothermal transducer 302 acts on the liquid to generate bubbles, and suddenly due to expansion and contraction of its volume. And a heat acting part 307 which is a part that causes various state changes.

  The heat acting part 307 is located above the heat generating part 308 of the electrothermal converter 302, and has a heat acting surface 309 as a surface in contact with the liquid of the heat generating part 308 as its bottom surface.

  The heat generating unit 308 includes a lower layer 310 provided on the substrate 303, a heat generating resistor layer 311 provided on the lower layer 310, and an upper layer 312 provided on the heat generating resistor layer 311.

  Electrodes 313 and 314 for energizing the heating resistor layer 311 are provided on the surface of the heating resistor layer 311 to generate heat.

  The electrode 313 is an electrode common to the heat generation part of each liquid discharge part, and the electrode 314 is a selection electrode for selecting the heat generation part of each liquid discharge part to generate heat, and the flow of the liquid discharge part It is provided along the road.

  The upper layer 312 fills the liquid flow path of the heat generating resistor layer 311 and the liquid discharge unit 306 in order to chemically and physically protect the heat generating resistor layer 311 from the liquid (for example, ink) used in the heat generating unit 308. The heating resistance layer 311 has a protective function of isolating the liquid from the liquid and preventing the electrodes 313 and 314 from being short-circuited through the liquid.

  In such a thermal method, it is basically easy to integrate the heating elements, and it is possible to arrange a plurality of discharge ports at a high density pitch, but it is used because the discharge principle uses the foaming phenomenon of water. The liquid to be used is limited to water-based ones.

  Next, an inkjet head using a piezoelectric / electrostrictive element as an actuator is, for example, a piezoelectric / electrostrictive element having a laminated structure in which piezoelectric / electrostrictive elements such as PZT (lead zirconate titanate) and electrode materials are alternately laminated. Is used as an actuator to displace the diaphragm by directly transmitting the piezoelectric / electrostrictive displacement of the piezoelectric / electrostrictive element to the diaphragm, and through the displaced diaphragm, a volume change is given to the individual liquid chamber to communicate with the liquid chamber. A so-called unimorph element, which discharges ink from the discharge port, or forms an electrode-piezoelectric / electrostrictive body-electrode on the vibration plate and bends the vibration plate due to electrostriction of the piezoelectric / electrostrictive body, is a piezoelectric / electric element. A strain element, in which ink is ejected from an ejection port communicating with the individual liquid chamber by changing the volume of the individual liquid chamber so that the diaphragm becomes at least one surface, has been put into practical use.

  Here, when the voltage applied to the piezoelectric / electrostrictive element is the same as the polarization direction, the piezoelectric / electrostrictive displacement of the actuator extends in the applied voltage direction with the piezoelectric constant being d33. In the opposite direction, a piezoelectric / electrostrictive displacement is generated that extends in the direction perpendicular to the applied voltage with the piezoelectric constant d31.

  Therefore, the displacement mode of d33 or d31 is generally used in the piezoelectric / electrostrictive element having the above-described laminated structure, and the displacement mode of d31 is generally used in the unimorph type piezoelectric / electrostrictive element.

  FIGS. 8 (a) and 8 (b) are a cross-sectional view and a plan view omitting a plan view of a representative example of an on-demand type ink jet head using the above-described unimorph type piezoelectric / electrostrictive element.

  Here, the ink droplet discharge means is a method in which an individual liquid chamber filled with ink is pressurized by a piezoelectric / electrostrictive element to discharge ink droplets, and is applied to the individual liquid chamber 202 formed in the substrate 201. Thus, the individual liquid chambers are formed by joining the diaphragms 203.

  On the diaphragm 203, a lower electrode 205, a piezoelectric / electrostrictive element 204, and an upper electrode 206 are laminated.

  In the individual liquid chamber 202, a common liquid chamber 208 communicating with the discharge port 207 and the individual liquid chamber 202 is formed.

  A series of these elements are formed in a row on the substrate, and a voltage is selectively applied between the upper and lower electrodes 205 and 206 by an image signal (driving signal) S, whereby the piezoelectric / electrostrictive element 204 is applied. Electrostriction occurs, and the diaphragm 203 bends rapidly.

  As a result, the volume of the individual liquid chamber 202 formed by the individual liquid chamber 202 and the vibration plate 203 is reduced, and the ink droplet D is ejected from the ejection port 207.

The features of this method are that the ink droplet size can be controlled by a method of applying a voltage to the piezoelectric / electrostrictive element, and the selection of the liquid (ink) material is relatively easy.
Japanese Patent Laid-Open No. 10-095150

  In recent years, the number of nozzles has been increased and the length of the printer head has been increased in order to realize higher-speed printing for inkjet printers. A plurality of printer heads are arranged in the direction perpendicular to the paper transport direction to move the head. A number of so-called line head printers that perform printing without doing so have also been proposed.

  For example, Japanese Patent Laid-Open No. 10-095150 proposes a line head printer that uses a full line type ink jet head that covers an A4 vertical size of 210 mm.

  In the head proposed here, for example, the printable width is set to about 220 mm by forming 5200 ejection ports at a density of 600 dpi (42.3 μm intervals).

  In recent years, the heads of inkjet printers are increasing in density in order to cope with higher image quality. For example, a line head having a density of 1200 dpi (21 μm intervals) requires 10400 ejection ports. Become.

  However, when a full-line inkjet head using a unimorph type piezoelectric / electrostrictive element as described above is made at a high-density pitch of 1200 dpi, for example, it is necessary to miniaturize and integrate each piezoelectric / electrostrictive element. However, as the size of the piezoelectric / electrostrictive element is reduced, the amount of flexure of the diaphragm due to the deformation of the piezoelectric / electrostrictive element is reduced, that is, the volume of ink excluded in the individual liquid chamber is reduced. Ink discharge becomes difficult.

  FIG. 9 is a schematic view of the displacement of the diaphragm 203 deformed by the piezoelectric / electrostrictive element when viewed from the direction perpendicular to the parallel direction of the individual liquid chambers.

  The volume of the individual liquid chamber originally formed by the individual liquid chamber 202 and the vibration plate 203 is reduced by the deformation of the vibration plate 203, and this corresponds to the ink removal volume.

  Since the individual liquid chamber width W is further reduced as the integration becomes higher as described above, the individual liquid chamber length L is generally parallel to the parallel direction of the individual liquid chambers as shown in FIG. In order to make the excluded volume of ink equal by extending the length, the individual liquid chamber (vibrating plate) width W << the individual liquid chamber (vibrating plate) length L.

  As a result, the piezoelectric / electrostrictive element 204, which is patterned to the size of the individual liquid chamber with the lower electrode 205 sandwiched between the surface of the diaphragm 203 on the individual liquid chamber 202, has a high aspect ratio on the individual liquid chamber length L side.

  Here, as shown in FIG. 10B, when a voltage is applied between the upper and lower electrodes of the piezoelectric / electrostrictive element 204, the d31 component has an individual liquid chamber width W of W to W-ΔW and an individual liquid chamber length due to the reverse piezoelectric effect. L is L to L-ΔL.

  At this time, the piezoelectric / electrostrictive element 204 expands and contracts in accordance with the aspect ratio with respect to the length direction rather than the width direction. Therefore, when the piezoelectric / electrostrictive element 204 is reduced, as shown in FIG. The deformation of 203 has a downward convex shape with a peak at the center of the individual liquid chamber length L, but the deformation in the individual liquid chamber width W direction becomes smaller as the length approaches the vicinity of the rear end of the distal end in the length direction. The excluded volume also decreases.

  Further, since an excessive load is applied to the bonding interface between the base 201 and the vibration plate 203 at the rear end in the longitudinal direction of the vibration plate 203, the bonding between the base 201 and the vibration plate 203 is peeled off, and the ink in the individual liquid chamber 202 is removed. The problem of leaking occurs.

  Here, even if the individual liquid chamber 202 and the vibration plate 203 are integrally formed with the base body 201, an excessive load is applied to the fringe portion, resulting in damage to the vibration plate 203.

  The present invention has been made in order to solve the above-described problems, and by providing a piezoelectric / electrostrictive element on a diaphragm, it is possible to achieve a high density ink jet head and to enable stable ink ejection. It is an object of the present invention to provide an ink jet head using a highly stable piezoelectric / electrostrictive actuator that enhances printing stability and does not cause head failure due to peeling of the joint.

  An on-demand ink jet printer head using the piezoelectric / electrostrictive actuator of the present invention is a piezoelectric comprising a lower electrode, a piezoelectric / electrostrictive body, and an upper electrode formed on diaphragms having four aspect ratios fixed to a base and having different aspect ratios. / A piezoelectric element in which at least one of the lower electrode, the piezoelectric element, the electrostrictive body, and the upper electrode of the electrostrictive element is arranged in a comb-teeth shape having a plurality of comb teeth perpendicularly or at an angle to the longitudinal direction of the diaphragm / The above-mentioned problem is solved by using an electrostrictive actuator.

  More specifically, a substrate having a plurality of individual liquid chambers, and a piezoelectric element comprising at least one surface of the individual liquid chambers and comprising a lower electrode, a piezoelectric / electrostrictive body, and an upper electrode corresponding to each individual liquid chamber. / The diaphragm in which the electrostrictive element is formed is deformed by deformation of the piezoelectric / electrostrictive element, and the volume of the individual liquid chamber is changed to change the liquid filled in each individual liquid chamber directly into each individual liquid chamber or In a piezoelectric / electrostrictive actuator used for an inkjet head that ejects from a discharge port that is indirectly communicated, under a piezoelectric / electrostrictive element that includes a lower electrode formed on a diaphragm, a piezoelectric / electrostrictive body, and an upper electrode. A piezoelectric / electrostrictive actuator in which at least one of an electrode, a piezoelectric / electrostrictive body, and an upper electrode is arranged in a comb-teeth shape having a plurality of comb teeth perpendicular to or at an angle to the longitudinal direction of the diaphragm is used. By the above section To resolve.

(Function)
According to the above-described structure of the present invention, the piezoelectric / electrostrictive element can be more deformed in the width direction of the individual liquid chamber than in the length direction of the individual liquid chamber, so that the excluded volume of the individual liquid chamber can be increased.

  Furthermore, it reduces the excessive load on the fringe part when the interface between the base and the diaphragm at the front end and the rear end of the diaphragm in the longitudinal direction, or when the individual liquid chamber and the diaphragm are manufactured integrally with the base. It is possible to improve the durability that ink leaks from the individual liquid chamber.

  An on-demand ink jet printer head using the piezoelectric / electrostrictive actuator of the present invention is a piezoelectric comprising a lower electrode, a piezoelectric / electrostrictive body, and an upper electrode formed on diaphragms having four aspect ratios fixed to a base and having different aspect ratios. / A piezoelectric element in which at least one of the lower electrode, the piezoelectric element, the electrostrictive body, and the upper electrode of the electrostrictive element is arranged in a comb-teeth shape having a plurality of comb teeth perpendicularly or at an angle to the longitudinal direction of the diaphragm / By using an electrostrictive actuator, the piezoelectric / electrostrictive element can be more deformed in the width direction of the individual liquid chamber than in the length direction of the individual liquid chamber, thus increasing the volume of the individual liquid chamber and increasing the head density. It becomes.

  Furthermore, it reduces the excessive load on the fringe part when the interface between the base and the diaphragm at the front end and the rear end of the diaphragm in the longitudinal direction, or when the individual liquid chamber and the diaphragm are manufactured integrally with the base. It is possible to improve the durability that ink leaks from the individual liquid chamber.

  Hereinafter, an on-demand inkjet printer head using a piezoelectric / electrostrictive actuator according to the present invention will be described in detail with reference to the drawings.

  FIG. 1A is an enlarged cross-sectional view when a printer head using the piezoelectric / electrostrictive actuator of the present embodiment is cut in parallel to the longitudinal direction of the diaphragm 103, and FIG. FIG. 3 is a partially enlarged view of the printer head as viewed from above.

  A feature of the present invention is that at least one of the lower electrode 105, the piezoelectric / electrostrictive body 104, and the upper electrode 106 that are piezoelectric / electrostrictive elements formed on the diaphragm 103 is perpendicular to the longitudinal direction of the diaphragm 103. Or it is arranging in the comb-tooth shape which has an angle and has several comb teeth.

  In this printer head, the substrate 101 made of a silicon substrate having a thickness of 200 μm is provided with a plurality of recesses by dry etching at an arrangement pitch of the discharge ports 107, and the substrate 101 and the diaphragm 103 are joined by covering with the diaphragm 103. A liquid chamber 102 is formed.

  Here, the individual liquid chamber 102 is formed with a width of 65 μm, a length of 3000 μm, and a depth of 100 μm, the front and rear ends in the longitudinal direction are narrowed, and the common liquid chamber 108 communicates with the rear end side.

  Further, a discharge port 107 is formed on the surface facing the surface covered with the diaphragm 103.

  Here, the vibration plate 103 is a portion that forms at least one surface of the individual liquid chamber 102 and is bent by deformation of the piezoelectric / electrostrictive element, and a portion that directly contacts the base 101 is not called the vibration plate 103. .

  The diaphragm 103 is a ceramic material that can be elastically deformed by the electrostriction of the piezoelectric / electrostrictive body 104, or a metal material such as zirconia, silicon, chromium, stainless steel, etc. 1-30 μm, preferably 1-15 μm thin plate. A piezoelectric / electrostrictive body 104 having a lower electrode 105 and an upper electrode 106 formed on the surface thereof is fixed in correspondence with each individual liquid chamber 102, and a signal from the drive power source S corresponding to the print signal is applied. Thus, a recording head using a piezoelectric / electrostrictive actuator can be configured.

  In the recording head configured as described above, the ink guided from an ink cartridge (not shown) is filled into the individual liquid chamber 102 from the common liquid chamber 108 through the aperture 109.

  Here, by applying a signal from the drive power source S to an arbitrary piezoelectric / electrostrictive element, the diaphragm 103 is bent, the volume of the individual liquid chamber 102 is changed, and the ink filled in the individual liquid chamber 102 is added. The ink droplet D is discharged from the discharge port 107.

  Next, the above-described piezoelectric / electrostrictive element will be described in detail with reference to FIG.

  The lower electrode 105 is patterned through a mask so as to have a comb shape at a position corresponding to the individual liquid chamber 102 on the vibration plate 103.

  Electrode materials such as Au, Ti, Pt, Cr, Al, Cu, Wsi, and W can be formed from 5 nm to 1 μm, preferably 5 nm to 300 nm, as a single layer or multiple layers by a conventionally known sputtering method, screen printing method, etc. The electrode is formed.

  If the film thickness of the electrode is too large, electrostriction of the piezoelectric / electrostrictive body 104 is hindered. Therefore, the film thickness is set to the above value. However, the electrode material, diaphragm material, piezoelectric / electrostrictive material, etc. It is determined in a timely manner according to mechanical properties such as rate.

  In this example, 4 nm of Ti was used as the anchor layer on the diaphragm 103 having a thickness of 3 μm, and 150 nm of Pt was used as the lower electrode 105 thereon.

  The piezoelectric / electrostrictive body 104 is formed with a PZT film by sputtering using a mask so as to cover the lower electrode 105.

  The film thickness of the piezoelectric / electrostrictive body 104 is 0.3 to 5 times, preferably 0.5 to 3 times the film thickness of the diaphragm 103, and in this example, a 3 μm MPB composition PZT thin film was used.

  Similarly, the upper electrode 106 is patterned under the same conditions as the lower electrode 105 through a mask so as to have a comb shape at a position corresponding to the piezoelectric / electrostrictive body 104 formed on the lower electrode 105.

  Here, the lower electrode 105, the piezoelectric / electrostrictive body 104, and the upper electrode 106 are formed such that the thickness of each comb tooth is lower electrode 105 <upper electrode 106 in order to avoid short circuit between the lower electrode 105 and the upper electrode 106. ≦ Piezoelectric / electrostrictive body 104.

  Further, the common electrode portion C105 of the lower electrode and the common electrode portion C106 of the upper electrode are patterned so as to be outside the frame of the individual liquid chamber 102 on both sides of the individual liquid chamber 102.

  This is to reduce the amount of electrostriction of the piezoelectric / electrostrictive body 104 at the fringe part of the individual liquid chamber 102 or the joint part of the base 101 and the diaphragm 103 as described above, and to reduce the load on the above part, In the present embodiment, the electrostriction lateral width (portion where a voltage is applied between the upper and lower electrodes and the reverse piezoelectric effect is generated) w is further narrower than the width of the individual liquid chamber 102 to reduce the load.

  Actually, since the spread of the electric field generated between the upper and lower electrodes differs depending on the thickness of the piezoelectric / electrostrictive body 104, the size of the piezoelectric / electrostrictive element, etc., the timely configuration is determined.

  The relationship between the electrostrictive longitudinal width l and the electrostrictive lateral width w of the electrostrictive region P is 1 ≦ w / l, more preferably 5 ≦ w / l. The amount increased, and the displacement amount of the diaphragm 103 was improved.

  With the configuration described above, the excluded volume of the individual liquid chamber 102 is increased, and even when the density of the head is increased, ink droplets can be ejected, and the durability of the head is improved.

  In this embodiment, the lower electrode 105, the piezoelectric / electrostrictive body 104, and the upper electrode 106 are each patterned into a comb shape by masking, but at least one of wet etching, dry etching, electroforming, dicing, etc. Can also be used to form a comb shape.

  The material of the substrate 101 is not limited to the silicon shown in this embodiment, but may be alumina, zirconia, silicon nitride, ceramic materials including glass, metal materials such as stainless steel, and various polymer materials.

  As for the method of forming the individual liquid chamber 102, the base 101 provided with the plurality of recesses as described above and the diaphragm 103 are joined by anodic bonding, Au-Au bonding, eutectic bonding, adhesive bonding, or the like. Alternatively, a part of the substrate may be left as a thin film by etching or the like, and this part may be integrated as a diaphragm and the other surface may be closed to form an individual liquid chamber.

  The processing means is not limited to dry etching as in the present embodiment, and conventionally known mechanical processing such as wet etching and punching can also be used.

Examples of the material used for the piezoelectric / electrostrictive body 104 include perovskite type compounds such as lead zirconate titanate PZT [Pb (Zr _x Ti _1-x ) O ₃ ] and barium titanate BaTiO _{3 described above.} An electrostrictive material such as a piezoelectric material or a relaxor material can be used.

  MP of lead zirconate titanate (PZT) preferably has a meso phase boundary (MPB) composition of 0.40 to 0.65, but other composition ratios may be used.

  The crystal structure of PZT may be either tetragonal or rhombohedral.

BaTiO ₃ is preferably a tetragonal (001) oriented film.

BaTiO ₃ may contain a trace amount of lead and bismuth.

  Moreover, the following can also be selected as an electrostrictive material used by this invention.

For example, PMN [Pb (Mg _x Nb _1-x ) O ₃ ], PNN [Pb (Nb _x Ni _1-x ) O ₃ ], PSN [Pb (Sc _x Nb _1-x ) O ₃ ], PZN [Pb ( Zn _x Nb _1-x ) O ₃ ], PMN-PT {(1-y) [Pb (Mg _x Nb _1-x ) O ₃ ] -y [PbTiO ₃ ], PSN-PT {(1-y) [ Pb (Sc _x Nb _1-x ) O ₃ ] -y [PbTiO ₃ ], PZN-PT {(1-y) [Pb (Zn _x Nb _1-x ) O ₃ ] -y [PbTiO ₃ ], LN [ LiNbO ₃ ] and KN [KNbO ₃ ].

  Here, x and y are numbers of 1 or less and 0 or more.

  For example, in the case of PMN, x is 0.2 to 0.5, and in PSN, x is preferably 0.4 to 0.7, y of PMN-PT is 0.2 to 0.4, y of PSN-PT is 0.35 to 0.5, and y of PZN-PT is 0.03 to 0.35 is preferred.

  Further, PMN-PZT, PZN-PZT, PNN-PZT, and PSN-PZT compounds in which Zr is substituted for Ti in PMN-PT, PZN-PT, PNN-PT, and PSN-PT may be used.

  The piezoelectric / electrostrictive body may have a single composition or a combination of two or more.

  Moreover, the composition which doped the trace amount element to the said main component may be sufficient.

  The piezoelectric / electrostrictive body of the present invention is preferably crystal-controlled in order to exhibit excellent piezoelectricity, and preferably has a specific orientation of 50% or more in a specific crystal structure by X-ray diffraction. Is more preferably 90% or more.

  These film formation processes include the above-described sputtering method, sol-gel method, ion beam method, molecular beam epitaxy method, laser ablation method, CVD (chemical vapor deposition) method, screen printing method, electrophoresis method, gas A deposition method, a hydrothermal synthesis method, or the like can be used.

  Further, it is needless to say that the present technology can also be used for conventionally known piezoelectric / electrostrictive actuator application technologies other than inkjet such as an ultrasonic motor and a scanner such as a micromirror device.

  Hereinafter, another embodiment of the on-demand ink jet printer head using the piezoelectric / electrostrictive actuator according to the present invention will be described in detail with reference to FIG.

  FIG. 3A is a partially enlarged view of the printer head as viewed from above, and FIG. 3B shows the printer head using the piezoelectric / electrostrictive actuator of this embodiment in the longitudinal direction of the diaphragm 403. It is a cross-sectional enlarged view when cut | disconnected perpendicularly | vertically with respect to FIG.

  Since the main configuration is the same as that of the first embodiment, the description is omitted.

  The feature of this embodiment is that the patterning is simplified by arranging the adjacent lower electrodes 405 in a comb-teeth shape that is in contact with the shape of the left-right symmetry.

  Here, the upper electrode 406 is patterned under the same conditions as in the first embodiment through a mask so as to have a comb shape at a position corresponding to the piezoelectric / electrostrictive body 404 formed on the lower electrode 405.

  Also in this embodiment, the common electrode portion of the lower electrode and the common electrode portion of the upper electrode are patterned so as to be outside the frame of the individual liquid chamber 402 on both sides of the individual liquid chamber 402.

  By adopting this configuration, the patterning density of the lower electrode 405 is at least half that of the upper electrode 406, so that the manufacturing process can be simplified.

  Hereinafter, another embodiment of the on-demand ink jet printer head using the piezoelectric / electrostrictive actuator according to the present invention will be described in detail with reference to FIG.

  FIG. 4 is a partially enlarged view of the printer head as viewed from above, and shows the layer configuration of the lower electrode 505, the piezoelectric / electrostrictive body 504, and the upper electrode 506 in a projected view.

  Since the main configuration is the same as that of the first embodiment, the description is omitted.

  The feature of the present embodiment is that the lower electrode 505, the piezoelectric / electrostrictive body 504, and the upper electrode 506 are arranged in different comb-teeth shapes. In particular, the piezoelectric / electrostrictive body 504 is arranged in the arrangement direction of the individual liquid chambers 502. Patterning is continued vertically.

  By adopting this configuration, at least the patterning accuracy of the piezoelectric / electrostrictive body 504 is not necessary, so that the manufacturing process can be simplified.

  Hereinafter, another embodiment of the on-demand inkjet printer head using the piezoelectric / electrostrictive actuator according to the present invention will be described in detail with reference to FIG.

  FIG. 5 is a partially enlarged view of the printer head as viewed from above, and shows the layer structure of the lower electrode 505, the piezoelectric / electrostrictive body 504, and the upper electrode 506 in a projected view.

  Since the main configuration is the same as that of the first embodiment, the description is omitted.

  A feature of the present embodiment is that the lower electrode 505, the piezoelectric / electrostrictive body 504, and the upper electrode 506 are arranged in substantially the same fishbone shape.

  Similar to the above-described embodiment, the lower electrode 605, the piezoelectric / electrostrictive body 604, and the upper electrode 606 are laminated and patterned through a mask so as to have a fishbone shape at the corresponding positions.

  Here again, the lower electrode 605, the piezoelectric / electrostrictive body 604, and the upper electrode 606 have a thickness of each comb tooth so that the lower electrode 605 and the upper electrode 606 are not short-circuited. ≦ Piezoelectric / electrostrictive body 1604.

  In the case of this configuration, the common electrode portion of the lower electrode and the upper electrode is patterned so as to be on the upper part of the individual liquid chamber 602, but since it is thin, the individual liquid chamber 602 is hardly bent in the longitudinal direction.

  The shape of the lower electrode, the piezoelectric / electrostrictive body, and the upper electrode may be a fishbone shape as shown in FIGS. 6 and 7, but is not limited thereto.

(A) is a cross-sectional enlarged view when the printer head in the embodiment of the present invention is cut parallel to the longitudinal direction of the diaphragm 103, and (b) is a view when the printer head is viewed from above. FIG. It is a detailed explanatory view of a piezoelectric / electrostrictive element in an example of the present invention. FIG. 5 is a detailed explanatory diagram of a piezoelectric / electrostrictive element in Example 2 of the present invention. FIG. 5 is a detailed explanatory diagram of a piezoelectric / electrostrictive element in Example 3 of the present invention. FIG. 6 is a detailed explanatory view of a piezoelectric / electrostrictive element in Example 4 of the present invention. FIG. 6 is a detailed explanatory diagram of another piezoelectric / electrostrictive element in Example 4 of the present invention. FIG. 6 is a detailed explanatory diagram of another piezoelectric / electrostrictive element in Example 4 of the present invention. It is sectional drawing and a plane abbreviate | omitted figure of the typical example of the on-demand-type inkjet head using the conventional unimorph type piezoelectric / electrostrictive element. 10 is a schematic diagram of the displacement of the diaphragm 203 deformed by the piezoelectric / electrostrictive element when viewed from a direction perpendicular to the parallel direction of the individual liquid chambers. It is sectional drawing and the plane omission figure of the head part of the conventional piezoelectric / electrostrictive type on-demand inkjet printer apparatus. It is sectional drawing of the head part of the conventional thermal type on-demand inkjet printer apparatus.

Explanation of symbols

101, 201 substrate
102, 202 Individual liquid chamber
103, 203 Diaphragm
104, 204 Piezoelectric / electrostrictive element
105, 205 Lower electrode
106, 206 Upper electrode Ink supply flow path
107, 207 Discharge port (nozzle)
108, 208 Common liquid chamber
109: Aperture
C Common electrode section
D ink droplet
S drive power supply
L Length of individual liquid chamber
W Individual liquid chamber width l Electrostrictive vertical width w Electrostrictive horizontal width
P Electrostrictive region

Claims (3)

  A lower electrode of a piezoelectric / electrostrictive element comprising a lower electrode, a piezoelectric / electrostrictive body, and an upper electrode formed on diaphragms having different aspect ratios fixed to the base in all directions, and at least of the piezoelectric / electrostrictive body and the upper electrode One is a piezoelectric / electrostrictive actuator, wherein the piezoelectric / electrostrictive actuator is arranged in a comb-teeth shape having a plurality of comb-teeth perpendicular to or at an angle to the longitudinal direction of the diaphragm.   A substrate having a plurality of individual liquid chambers, and a piezoelectric / electrostrictive element that forms at least one surface of the individual liquid chambers and includes a lower electrode, a piezoelectric / electrostrictive body, and an upper electrode corresponding to each of the individual liquid chambers. The formed diaphragm is deformed by the deformation of the piezoelectric / electrostrictive element, and the volume of each individual liquid chamber is changed so that the liquid filled in each individual liquid chamber communicates directly or indirectly with each individual liquid chamber. In a piezoelectric / electrostrictive actuator used for an ink jet head ejected from an ejection port, a lower electrode formed on a diaphragm, a piezoelectric / electrostrictive body, and a piezoelectric / electrostrictive element composed of an upper electrode and a piezoelectric / electrostrictive element. 2. The piezoelectric / electrode according to claim 1, wherein at least one of the strain body and the upper electrode is arranged in a comb-teeth shape having a plurality of comb teeth perpendicular to or at an angle to the longitudinal direction of the diaphragm. Electrostrictive actuator.   2. The aspect ratio of each comb tooth in the comb-shaped piezoelectric / electrostrictive element formed on the vibration plate is such that a ratio of a vertical direction to a longitudinal direction of the vibration plate is 1 or more. Piezoelectric / electrostrictive actuator.

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