JP2014175507A - Piezoelectric element, droplet discharge head, liquid cartridge, and droplet discharge recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element which easily determines deficiency and excess in the polarization state at a piezoelectric material after polarization treatment.SOLUTION: A piezoelectric element 1 includes: a first electrode 3; first wiring 9 electrically connected with the first electrode 3; a second electrode 7; second wiring 11 electrically connected with the second electrode 7; a piezoelectric material 5 disposed between the first electrode 3 and the second electrode 7; and multiple current detection wiring lines 13a, 13b, 13c disposed at the first wiring 9 and having allowable current values different from each other.

Description

  The present invention relates to a piezoelectric element, a droplet discharge head, a liquid cartridge, and a droplet discharge recording apparatus.

  In a piezoelectric element using a piezoelectric body, it is known that polarization processing (polling) is performed on the piezoelectric body (see, for example, Patent Document 1). The polarization treatment is performed by applying a direct current high voltage (for example, about 2 to 5 kV / mm) to the piezoelectric body through electrodes arranged so as to sandwich the piezoelectric body under a temperature condition of about room temperature to about 200 ° C. The polarization treatment is performed in order to give directionality to the spontaneous polarization inside the piezoelectric body and to obtain the piezoelectricity by giving the remanent polarization.

  The polarization process is performed by applying a DC high voltage from the input electrode to the piezoelectric body disposed between the ground electrode and the input electrode. At this time, a current flows from the input electrode through the piezoelectric body to the ground electrode. This current value increases or decreases according to the polarization state inside the piezoelectric body. Therefore, as a result, the polarization state of the piezoelectric body may be excessive or insufficient.

  In particular, in a device in which a large number of piezoelectric elements are arranged independently, such as an ink-jet head, appropriate polarization processing is performed individually due to variations in piezoelectric elements in the surface, malfunctions in the circuit, and the like. It is difficult. When an excessive voltage is applied to the piezoelectric element during the polarization process, the piezoelectric element itself is broken down, or the piezoelectric body is not properly polarized and the polarization process is insufficient.

  Patent Document 1 discloses a polarization process in which a light-emitting diode is turned on and discriminated when a piezoelectric element breaks down during polarization processing in order to provide a polarization processing apparatus that can determine a piezoelectric element that has undergone dielectric breakdown after polarization processing. An apparatus is disclosed.

  However, the polarization processing apparatus disclosed in Patent Document 1 has a problem that it cannot identify a piezoelectric element that is insufficient in the polarization processing of the piezoelectric body.

  An object of the present invention is to provide a piezoelectric element that can easily determine the excess or deficiency of the polarization state in a piezoelectric body after polarization treatment.

  A piezoelectric element according to the present invention includes a piezoelectric body, a pair of electrodes arranged with the piezoelectric body interposed therebetween, and a current detection wiring portion electrically connected to one of the pair of electrodes, The current detection wiring section includes a plurality of current detection wirings connected in parallel and having different allowable current values.

  An object of the present invention is to provide a piezoelectric element that can easily determine the excess or deficiency of the polarization state in a piezoelectric body after polarization treatment.

It is the schematic plan view and sectional drawing for demonstrating one Example of a piezoelectric element. It is sectional drawing for demonstrating an example of the production method of the piezoelectric element shown by FIG. FIG. 3 is a cross-sectional view for explaining an example of a method for producing the piezoelectric element shown in FIG. 1, for explaining a process subsequent to FIG. 2. It is a figure for demonstrating the state of the electric current detection wiring after the polarization process in one Example of a piezoelectric element. It is a graph for demonstrating the example of the electric current which flows into each current detection wiring with respect to the electric current which flows into a ground electrode at the time of a polarization process. It is a schematic exploded perspective view for explaining one example of a droplet discharge head. It is a schematic sectional drawing for demonstrating the Example. It is the schematic sectional drawing which expanded and showed a part of FIG. It is a schematic perspective view for demonstrating one Example of a liquid cartridge. 1 is a schematic perspective view for explaining an embodiment of a droplet discharge recording apparatus. It is a schematic side view for demonstrating the mechanism part of the Example. It is a schematic top view for demonstrating the other Example of a piezoelectric element. It is a schematic top view for demonstrating the further another Example of a piezoelectric element. It is a schematic top view for demonstrating the further another Example of a piezoelectric element. It is a schematic top view for demonstrating the further another Example of a piezoelectric element. It is a schematic top view for demonstrating the further another Example of a piezoelectric element. It is a schematic top view for demonstrating the further another Example of a piezoelectric element.

  If the current value that has flowed through the piezoelectric body during the polarization process can be determined for the piezoelectric element that has been subjected to the polarization process, it is possible to determine whether the polarization state of the piezoelectric body is excessive or insufficient. The piezoelectric element of the present invention includes a current detection wiring portion that is electrically connected to one of a pair of electrodes arranged with a piezoelectric body interposed therebetween. The current detection wiring unit includes a plurality of current detection wirings connected in parallel and having different allowable current values. Here, the allowable current value of the current detection wiring means a minimum current value at which the current detection wiring is broken.

  For example, in the piezoelectric element of the present invention, when a current having an appropriate current value in the polarization process flows to the piezoelectric body during the polarization process, at least one current detection wiring is set to be broken and the remaining current detection lines are set not to be broken. Is done. Further, it is set such that at least one of the current detection wirings is further broken when a current larger than the appropriate current value flows through the piezoelectric body during the polarization process. The piezoelectric element of the present invention can easily determine the excess or deficiency of the polarization state in the piezoelectric body after the polarization process by reading the broken current detection wiring after the polarization process. Thereby, the piezoelectric element of this invention can improve the reliability of a piezoelectric element.

  A liquid droplet ejection head according to the present invention generates a pressure through a diaphragm in a nozzle layer having nozzle holes, a flow path layer that forms a liquid chamber communicating with the nozzle holes, and a fluid flowing in the liquid chamber. A droplet discharge head including a piezoelectric element, wherein the piezoelectric element is the piezoelectric element of the present invention. Since the droplet discharge head according to the present invention includes the piezoelectric element according to the present invention, the reliability of the piezoelectric element is improved, and as a result, the reliability of the entire droplet discharge head can be improved.

  The liquid cartridge according to the present invention is a liquid cartridge in which a liquid droplet discharge head for discharging liquid droplets and a liquid tank for supplying liquid to the liquid droplet discharge head are integrated. It is a droplet discharge head. Since the liquid cartridge of the present invention includes the liquid droplet ejection head of the present invention, the reliability of the liquid droplet ejection head can be improved, and as a result, the reliability of the entire liquid cartridge can be improved.

  A droplet discharge recording apparatus according to the present invention is a droplet discharge recording apparatus including a droplet discharge head that discharges droplets, and the droplet discharge head is the droplet discharge head of the present invention. . Since the droplet discharge recording apparatus of the present invention includes the droplet discharge head of the present invention, the reliability of the droplet discharge head can be improved, and as a result, the reliability of the entire droplet discharge recording apparatus can be improved. .

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic plan view and cross-sectional view for explaining an embodiment of a piezoelectric element. In FIG. 1, the cross-sectional view shows a cross section at the position AA ′ in the plan view. In the plan view of FIG. 1, the illustration of the interlayer insulating film and the protective film is omitted.

  The piezoelectric element 1 includes a lower electrode 3 (first electrode or second electrode), a piezoelectric body 5, an upper electrode 7 (second electrode or first electrode), a ground wiring 9 (first wiring or second wiring), and an input wiring. 11 (second wiring or first wiring) and a current detection wiring section 13.

  The lower electrode 3 is formed on the base material 15 via the insulating film 17. The base material 15 is, for example, a silicon wafer. The insulating film 17 is, for example, a silicon oxide film.

  A piezoelectric body 5 is formed on the lower electrode 3. An upper electrode 7 is formed on the piezoelectric body 5. The piezoelectric body 5 is disposed between the lower electrode 3 and the upper electrode 7.

  An interlayer insulating film 19 is formed on the insulating film 17 so as to cover the laminated body of the lower electrode 3, the piezoelectric body 5 and the upper electrode 7. In the interlayer insulating film 19, connection holes are formed at predetermined positions on the lower electrode 3 and predetermined positions on the upper electrode 7, respectively.

  A ground wiring 9 and an input wiring 11 are formed on the interlayer insulating film 19. The ground wiring 9 is electrically connected to the lower electrode 3 through a connection hole formed in the interlayer insulating film 19 on the lower electrode 3. The input wiring 11 is electrically connected to the upper electrode 7 through a connection hole formed in the interlayer insulating film 19 on the upper electrode 7.

  A passivation film 21 is formed on the interlayer insulating film 19 so as to cover the ground wiring 9 and the input wiring 11. In the passivation film 21, pad openings are respectively formed at predetermined positions on the ground wiring 9 and predetermined positions on the input wiring 11. The portion of the ground wiring 9 exposed at the pad opening constitutes the ground electrode 23. The portion of the input wiring 11 exposed at the pad opening constitutes the input electrode 25.

  The current detection wiring portion 13 is disposed on the ground wiring 9 between the lower electrode 3 and the ground electrode 23. The current detection wiring unit 13 includes current detection wirings 13a, 13b, and 13c. The current detection wirings 13a, 13b, and 13c are connected in parallel. The current detection wirings 13a, 13b, and 13c have different resistance values and allowable current values due to different widths.

  2 and 3 are cross-sectional views for explaining an example of a method for producing the piezoelectric element shown in FIG. 2 and 3 correspond to the A-A 'position in FIG. The parentheses for each step described below correspond to the parentheses in FIGS.

(1) An insulating film 17, a lower electrode film 3a, a piezoelectric film 5a, and an upper electrode film 7a are sequentially formed on a base material 15 made of, for example, a silicon wafer.

(2) The upper electrode film 7a is patterned by photolithography and etching techniques to form the upper electrode 7.

(3) The piezoelectric film 5 is formed by patterning the piezoelectric film 5a while protecting the upper electrode 7 by photolithography and etching techniques.

(4) The lower electrode 3 is formed by patterning the lower electrode film 5a while protecting the upper electrode 7 and the piezoelectric body 5 by photolithography and etching techniques.

(5) An interlayer insulating film 19 is formed on the entire surface. A connection hole is formed at a predetermined position of the interlayer insulating film 19 on the lower electrode 3 and the upper electrode 7 by photolithography and etching techniques.

(6) A metal material film made of, for example, aluminum is formed on the entire surface. The metal material film is subjected to a patterning process by a photoengraving technique and an etching technique to form the ground wiring 9 and the input wiring 11. At this time, the current detection wiring portion 13 is formed in the ground wiring 9.

(7) A passivation film 21 is formed on the entire surface. Pad openings are formed at predetermined positions on the passivation film 21 on the ground wiring 9 and the input wiring 11 by photolithography and etching techniques. A portion of the ground electrode 23 of the ground wiring 9 is exposed through the pad opening. The portion of the input electrode 25 of the input wiring 11 is exposed through the pad opening.

  FIG. 4 is a diagram for explaining the state of the current detection wiring after the polarization processing. FIG. 5 is a chart for explaining an example of a current flowing through each current detection wiring with respect to a current flowing through the ground electrode during the polarization process. In FIG. 5, charts (A), (B), and (C) correspond to the states of the current detection wiring portions in (A), (B), and (C) of FIG. 4.

  An appropriate current value that flows through the ground electrode 23 (piezoelectric body 5) during the polarization treatment is, for example, about 1.75 to 2.5 mA (milliampere), although it depends on the polarization condition and the structure of the piezoelectric element. The resistance ratio of the current detection wirings 13a, 13b, 13c of the current detection wiring unit 13 is, for example, 15: 10: 6. Here, the resistance ratio means a ratio of resistance values. For example, the allowable current value of the current detection wiring 13a is about 0.35 mA, the allowable current value of the current detection wiring 13b is about 0.93 mA, and the allowable current value of the current detection wiring 13c is about 5.0 mA.

The reason why the polarization state can be determined from the state of the current detection wiring after the polarization process will be described below.
In the state of the current detection wiring portion 13 shown in FIG. 4A, none of the current detection wirings 13a, 13b, 13c arranged in parallel is broken. Since the current detection wiring 13a having the smallest allowable current value is not broken, it can be determined that the current value flowing to the ground electrode 23 during the polarization process is 1.75 mA or less (see FIG. 5A). ). Since the current value flowing through the ground electrode 23 is less than the appropriate current value during the polarization process, it is suspected that the applied voltage is insufficient during the polarization process or there is a short-circuit portion on the circuit, and the polarization state of the piezoelectric body 5 is insufficient. Can be determined.

  In the state of the current detection wiring portion 13 shown in FIG. 4B, the current detection wiring 13a is broken and the current detection wirings 13b and 13c are not broken. Therefore, it can be determined that the value of the current flowing through the ground electrode 23 during the polarization process is 1.75 mA or more and smaller than 2.5 mA (see FIG. 5B). In the piezoelectric element 1 shown in FIG. 4B, a current having an appropriate current value flows at the time of polarization processing, so that it can be determined that the polarization state of the piezoelectric body 5 is appropriate.

  In the state of the current detection wiring portion 13 shown in FIG. 4C, the current detection wirings 13a and 13b are broken and the current detection wiring 13c is not broken. Therefore, it can be determined that the current value flowing through the ground electrode 23 during the polarization process is 2.5 mA or more and smaller than 5 mA (see FIG. 5C). In the piezoelectric element 1 shown in FIG. 4C, a current larger than an appropriate current value flows during the polarization process, so that it can be determined that the polarization state of the piezoelectric body 5 is an excessive state.

  In the state of the current detection wiring portion 13 shown in FIG. 4D, all of the current detection wirings 13a, 13b, and 13c are broken. Since the current detection wiring 13c is broken, it can be seen that an excessive current flows through the ground electrode 23 during the polarization process. It is suspected that the dielectric breakdown of the piezoelectric element 1, the presence of a leak between the upper electrode 7 and the lower electrode 3, the presence of a leak location on another circuit, etc.

  As described above, in this embodiment, the current detection wirings 13a, 13b, and 13c having different resistance ratios and allowable current values are installed in parallel, and the state of the current detection wirings 13a, 13b, and 13c after the polarization process is confirmed. This makes it possible to determine whether or not the piezoelectric element 1 has been subjected to an appropriate polarization process. Furthermore, not only the polarization state of the piezoelectric body 5 of the piezoelectric element 1 but also the quality of the piezoelectric element 1 and the circuit itself can be easily determined by appearance observation. Thus, the reliability of the piezoelectric element 1 determined to be non-defective is improved.

  As long as the plurality of current detection wirings arranged in parallel are sequentially broken, a resistance ratio other than the above or an allowable current value may be used.

  Moreover, in the state (refer FIG.4 (B)) in which it polarized appropriately, some (current detection wiring 13a) among the several current detection wiring 13a, 13b, 13c is fractured | ruptured, but others The current detection wirings 13b and 13c are not broken. Since the drive voltage condition of a normal piezoelectric element is less than or equal to the voltage condition necessary for polarization processing, the piezoelectric element 1 functions as a drive circuit due to the presence of the remaining current detection wirings 13b and 13c. Therefore, the piezoelectric element 1 with the current detection wiring 13a broken can be handled as a non-defective product as it is.

  FIG. 6 is a schematic exploded perspective view for explaining an embodiment of the droplet discharge head. FIG. 7 is a schematic sectional view for explaining the embodiment. The cross section in FIG. 7 corresponds to the position B-B ′ in FIG. 6. FIG. 8 is a schematic cross-sectional view showing an enlarged part of FIG. 7 and 8 are turned upside down with respect to FIG. 6 for convenience. In FIG. 8, the nozzle cover, the packing plate, and the damper plate are not shown.

  In this embodiment, the piezoelectric element of the present invention is applied to the droplet discharge head, but the apparatus to which the piezoelectric element of the present invention is applied is not limited to the droplet discharge head. The droplet discharge head to which the piezoelectric element of the present invention is applied is not limited to the droplet discharge head of this embodiment.

  An ink jet head will be described as an example of the droplet discharge head 101. The droplet discharge head 101 includes a nozzle cover 102, a nozzle plate (nozzle layer) 103, an actuator substrate 104, a backing plate 105, a damper plate 106, a frame 107, and an FPC (Flexible printed circuits) 108. The nozzle plate 103, the actuator substrate 104, the backing plate 105, and the damper plate 106 are stacked in that order and fixed to the frame 107 by the nozzle cover 102.

  A large number of nozzle holes 109, which are fine holes for causing ink droplets to fly, are formed in the nozzle plate 103. On the actuator substrate 104, a flow path substrate 111 (flow path layer) including individual liquid chambers 110 that individually communicate with the nozzle holes 109 is formed. The individual liquid chamber 110 includes a pressurized liquid chamber section 112, a fluid resistance section 113, and an ink supply section 114.

The nozzle hole 109 is disposed corresponding to the tip position of the pressurized liquid chamber portion 112 of the corresponding individual liquid chamber 110. The diameter of the nozzle hole 109 is, for example, 10 to 35 μm (micrometer).
The nozzle plate 103 is formed of a resin film such as polyimide, for example. Further, as a material of the nozzle plate 103, for example, a nickel metal plate manufactured by an electroforming method, silicon, or other metal material can be used. The nozzle plate 103 is formed with a water-repellent surface treatment film.

  The individual liquid chamber 110 is formed as a part of the actuator substrate 104, and is formed by processing a flow path substrate 111 made of, for example, silicon. The individual liquid chamber 110 is provided for each nozzle hole 109. For example, the flow path substrate 111 is formed by a photolithography technique and a silicon deep digging dry etching technique using a fluorine-based gas by an ICP (Inductively Coupled Plasma) etcher. Usually, an etching process for forming the individual liquid chamber 110 on the flow path substrate 111 is performed after a drive element portion on the surface of the actuator substrate 104 described later is formed and the silicon substrate thickness is reduced to about 100 μm by backside polishing. Done.

  In the actuator substrate 104, a diaphragm 115 is disposed on the flow path substrate 111. The piezoelectric element 1 is formed on the vibration plate 115. The diaphragm 115 is a part for transmitting the pressure generated by the piezoelectric element 1 to the ink in the pressurized liquid chamber 112. The diaphragm 115 is made of, for example, a single film or a composite film such as a silicon oxide film, a silicon nitride film, or a polysilicon film, and is formed using a diffusion furnace, a CVD (Chemical Vapor Deposition) apparatus, or the like. The film thickness of the diaphragm 115 is, for example, about 0.5 to 3 μm as the total film thickness of the laminated films.

  The piezoelectric element 1 includes a lower electrode 3, a piezoelectric body 5, an upper electrode 7, a ground wiring (not shown) electrically connected to the lower electrode 3, an input wiring 11, and a current detection wiring section 13. The lower electrode 3 is disposed on the diaphragm 115. On the lower electrode 3, a piezoelectric body 5 and an upper electrode 7 are laminated in that order. The input wiring 11 is electrically connected to the upper electrode 7.

  The current detection wiring unit 13 is disposed on the input wiring 11. The current detection wiring unit 13 includes a plurality of current detection wirings having different allowable current values. For example, the configuration of the current detection wiring unit 13 is the same as the configuration shown in FIG. 1 except that the current detection wiring is arranged in the input wiring 11. Note that the current detection wiring unit 13 includes at least one current detection wiring that is broken during the polarization process as a plurality of current detection wirings.

  In this embodiment, the lower electrode 3 and the ground wiring are used as a common electrode and wiring for the plurality of piezoelectric elements 1, and the upper electrode 7 and the input wiring 11 are used as individual electrodes for each piezoelectric element 1.

  The piezoelectric body 5 of the piezoelectric element 1 is displaced (deformed) by the voltage supplied from the lower electrode 3 and the upper electrode 7. The diaphragm 115 is displaced by the displacement of the piezoelectric body 5, and the pressure in the pressurized liquid chamber 112 is changed.

The material of the piezoelectric body 5 is, for example, PZT (lead zirconate titanate) formed by a sol-gel method. The film thickness of the piezoelectric body 5 is, for example, about 1 to 2 μm. However, the material and film thickness of the piezoelectric body 5 are not limited to this. For example, the material of the piezoelectric body 5 includes BaTiO ₃ (barium titanate) in addition to PZT.

  Examples of the material of the lower electrode 3 and the upper electrode 7 include low resistance materials such as Pt (platinum), Au (gold), and In (indium). The lower electrode 3 and the upper electrode 7 are formed by, for example, a sputtering method, a photolithography technique, and an etching technique. The film thickness of the lower electrode 3 and the upper electrode 7 is, for example, about 100 to 200 nm (nanometers). The material of the lower electrode 3 and the upper electrode 7 may be different from each other. Further, the film thickness of the lower electrode 3 and the film thickness of the upper electrode 7 may be different from each other.

  An interlayer insulating film 120 is formed on the vibration plate 115 so as to cover the piezoelectric element 1. An input wiring 11 is formed on the interlayer insulating film 120. The input wiring 11 and the upper electrode 7 are electrically connected through a connection hole provided in the interlayer insulating film 120.

  The interlayer insulating film 120 is, for example, a laminated film of a silicon oxide film by an ALD (atomic layer deposition) method and a silicon oxide film by a plasma CVD method. The total film thickness of the laminated films constituting the interlayer insulating film 120 is, for example, 0.5 to 1 μm.

  The material of the input wiring 11 is, for example, aluminum. The input wiring 11 is formed by, for example, a sputtering method, a photolithography technique, and an etching technique. The film thickness of the input wiring 11 is, for example, 1 to 3 μm. As described above, the current detection wiring portion 13 is formed in the input wiring 11.

A passivation film 122 is formed on the interlayer insulating film 120 so as to cover the input wiring 11. The passivation film 122 blocks the internal structure of the actuator substrate 104 from the outside air. A pad opening 124 for electrical connection with the external input 123 is formed in the passivation film 122 on the pad portion of the input wiring 11.
The material of the passivation film 122 is, for example, a silicon nitride film formed by plasma CVD. The thickness of the passivation film 122 is, for example, 0.7 to 1.5 μm.

  The external input 123 is, for example, an IC (Integrated Circuit) chip. The external input 123 controls voltage application to the piezoelectric element 1 through the input wiring 11. The external input 123 is electrically connected to the outside of the droplet discharge head 101 via the FCP 108 shown in FIG. The connection method between the pad portion of the input wiring 11 and the external input 123 is, for example, a stud bump method. However, the external input 123 and the connection method are not limited to these.

  A protective substrate 126 is disposed on the passivation film 122 via an adhesive 125. The protective substrate 126 is for complementing the rigidity of the actuator substrate 104. The protective substrate 126 includes a recess 127 that covers the formation region of the piezoelectric element 1 and an ink supply hole 128 that is a through hole that communicates with the ink supply unit 114 of the individual liquid chamber 110. The ink supply hole 128 communicates with the ink supply unit 114 through a through hole formed in the passivation film 122, the interlayer insulating film 120, and the diaphragm 115.

  For example, the protective substrate 126 is formed by processing a silicon substrate having a thickness of about 400 μm. For example, the protective substrate 126 is formed by a photolithography technique and a silicon deep digging dry etching technique using a fluorine-based gas by an ICP etcher.

Next, the ink flow will be described.
The ink supplied to the ink supply hole 128 flows into the pressurized liquid chamber portion 112 via the ink supply portion 114 and the fluid resistance portion 113 of the individual liquid chamber 110. The pressurized liquid chamber 112 is filled with ink.

  Displacement occurs in the piezoelectric body 5 when an input (voltage) from the external input 123 mounted on the actuator substrate 104 is applied to the upper electrode 7 of the piezoelectric element 1 via the input wiring 11. The lower electrode 3 is a circuit that is electrically grounded (not shown). The displacement of the piezoelectric body 5 generates a pressure in the pressurized liquid chamber 112 via the vibration plate 115. As a result, the ink droplet 129 is ejected from the nozzle hole 109.

  The droplet discharge head 101 includes a piezoelectric element 1 as an embodiment of the present invention. Therefore, the droplet discharge head 101 can improve the reliability related to the piezoelectric element 1 and can improve the reliability of the droplet discharge head 101 as a whole.

FIG. 9 is a schematic perspective view for explaining an embodiment of the liquid cartridge.
The liquid cartridge 201 is obtained by integrating the droplet discharge head 101 of the above-described embodiment having the nozzle hole 109 and the like, and the liquid tank 202 that supplies liquid to the droplet discharge head 101.

  In the case of the liquid cartridge 201 integrated with a liquid tank, the performance of the droplet discharge head 101 immediately leads to the performance of the entire liquid cartridge 201. Therefore, by using the highly reliable droplet discharge head 101, a highly reliable liquid can be obtained. A cartridge 201 can be obtained.

  FIG. 10 is a schematic perspective view for explaining an embodiment of the droplet discharge recording apparatus. FIG. 11 is a schematic side view for explaining the mechanism of this embodiment.

  The droplet discharge recording apparatus 301 houses a printing mechanism unit 303 including a carriage 310, a recording head 311, an ink cartridge 312 and the like. The carriage 310 is arranged inside the recording apparatus main body 302 so as to be movable in the main scanning direction. The recording head 311 includes a droplet discharge head that implements the present invention, and is mounted on the carriage 310. The ink cartridge 312 is for supplying ink to the recording head 311.

  In the droplet discharge recording apparatus 301, a sheet feeding cassette (or a sheet feeding tray) 305 capable of stacking a large number of sheets 304 from the front side is detachably attached to a lower portion of the recording apparatus main body 302. it can. Further, the droplet discharge recording apparatus 301 can open the manual feed tray 306 for manually feeding the paper 304.

  The droplet discharge recording device 301 takes in the paper 304 fed from the paper feed cassette 305 or the manual feed tray 306, records a required image by the printing mechanism unit 303, and then onto a paper discharge tray 307 mounted on the rear side. Eject paper.

  The printing mechanism unit 303 holds the carriage 310 slidably in the main scanning direction (perpendicular to the paper in FIG. 11) with a main guide rod 308 and a sub guide rod 309 which are guide members horizontally mounted on left and right side plates (not shown). doing.

  Mounted on the carriage 310 is a recording head 311 comprising a droplet discharge head according to the present invention for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). The recording head 311 has a plurality of ink ejection openings (nozzles) arranged in a direction crossing the main scanning direction, and is mounted on the carriage 310 with the ink droplet ejection direction facing downward. In addition, each ink cartridge 312 for supplying ink of each color to the recording head 311 is replaceably mounted on the carriage 310.

  The ink cartridge 312 has an air port that communicates with the atmosphere above, and a supply port that supplies ink to the inkjet head below. A porous body filled with ink is disposed inside the ink cartridge 312. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of the porous body. Further, although the recording heads 311 of the respective colors are used here as the recording heads, a single head having nozzles that eject ink droplets of the respective colors may be used.

  Here, the carriage 310 is slidably fitted to the main guide rod 308 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 309 on the front side (upstream side in the paper conveyance direction). It is location. In order to move and scan the carriage 310 in the main scanning direction, a timing belt 316 is stretched between a driving pulley 314 and a driven pulley 315 that are rotationally driven by a main scanning motor 313. The carriage 310 is fixed to the timing belt 316, and the carriage 310 is reciprocated by forward and reverse rotation of the main scanning motor 313.

  In order to convey the sheet 304 set in the sheet feeding cassette 305 to the lower side of the recording head, a sheet feeding roller 317, a friction pad 318, a guide member 319, a conveying roller 320, a conveying roller 321 and a leading end roller 322 are provided. . A paper feed roller 317 and a friction pad 318 separate and feed the paper 304 from the paper feed cassette 305. A guide member 319 guides the sheet 304. The conveyance roller 320 inverts and conveys the fed sheet 304. The conveyance roller 321 is pressed against the peripheral surface of the conveyance roller 320. The leading end roller 322 defines the feed angle of the sheet 304 from the transport roller 320. The conveyance roller 320 is rotationally driven by a sub-scanning motor 323 through a gear train.

  A printing receiving member 324 is provided as a paper guide member for guiding the paper 304 fed from the conveying roller 320 below the recording head 311 corresponding to the range of movement of the carriage 310 in the main scanning direction. On the downstream side of the printing receiving member 324 in the sheet conveyance direction, a conveyance roller 325 and a spur 326 that are rotationally driven to send out the sheet 304 in the sheet discharge direction are provided. Further, a paper discharge roller 327 and a spur 328 for sending the paper 304 to the paper discharge tray 307, and guide members 329 and 330 for forming a paper discharge path are provided.

  At the time of recording, the recording head 311 is driven according to the image signal while moving the carriage 310 to eject ink onto the stopped paper 304 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the sheet 304 has reached the recording area, the recording operation is terminated and the sheet 304 is discharged.

  A recovery device 331 for recovering the ejection failure of the recording head is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 310. The recovery device 331 includes a cap unit, a suction unit, and a cleaning unit. The carriage 310 is moved to the recovery device 331 side during printing standby, and the recording head is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  In case of ejection failure, etc., the ejection port (nozzle) of the recording head is sealed with a capping unit, air bubbles are sucked out together with ink from the ejection port with a suction unit through the tube, and ink or dust adhered to the ejection port surface Is removed by the cleaning means to recover the ejection failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  Thus, in the droplet discharge recording apparatus 301, the recording head 311 composed of a droplet discharge head to which the piezoelectric element of the present invention is applied is mounted. Since the performance of the droplet discharge head immediately leads to the overall performance of the droplet discharge recording apparatus 301, a highly reliable droplet discharge recording apparatus 301 can be obtained by using a highly reliable droplet discharge head. .

  In the above embodiment, the liquid droplet ejection head of the present invention is applied to an ink jet head. However, the present invention can also be applied to a liquid droplet ejection head that ejects liquid droplets other than ink, for example, a liquid resist for patterning.

  FIG. 12 is a schematic plan view for explaining another embodiment of the piezoelectric element. In FIG. 12, parts having the same functions as those in FIG.

  In the piezoelectric element 1 of this embodiment, the resistance values of the current detection wirings 13a, 13b, and 13c are set to the same value in the current detection wiring portion 13 as compared with the embodiment shown in FIG. The current detection wirings 13a, 13b, and 13c have mutually different allowable current values due to their different line widths. Further, the current detection wirings 13a, 13b, and 13c have the same resistance value because of their different lengths.

  For example, it is assumed that an appropriate current value flowing through the piezoelectric body 5 during the polarization process is 1.75 to 2.5 mA. At this time, the current detection wiring 13a is set to have a resistance value and a line width that are broken by a current of about 0.58 mA (1.75 mA × 1/3).

  Since the resistance values of the current detection wirings 13a, 13b, and 13c are the same value, when the current detection wiring 13a is broken, the current detection wirings 13b and 13c are compared with the case where the current detection wiring 13a is not broken. Five times as much current flows.

  The current detection wiring 13b is set to a line width that is broken by a current of about 1.25 mA (2.5 mA × 1/2). The length of the current detection wiring 13b is set based on the same resistance value of the current detection wirings 13a, 13b, and 13c.

  When the current detection wirings 13a and 13b are broken, all currents flowing between the input electrode 25 and the ground electrode 23 flow through the current detection wiring 13c.

  The current detection wiring 13c is set to a current value that can detect dielectric breakdown or circuit abnormality of the piezoelectric element 1, for example, a line width that is broken by a current of about 5 mA. Note that the length of the current detection wiring 13c is set based on the same resistance value of the current detection wirings 13a, 13b, and 13c.

  In the current detection wiring portion 13 after the polarization process, if the current detection wiring 13a is not broken, the polarization state of the piezoelectric body 5 is insufficient as described with reference to FIG. Can be determined.

  In the current detection wiring portion 13 after the polarization processing, if the current detection wiring 13a is broken and the current detection wirings 13b and 13c are not broken, as in the case described with reference to FIG. It can be determined that the polarization state of the body 5 is appropriate.

  In the current detection wiring portion 13 after the polarization treatment, if the current detection wirings 13a and 13b are broken and the current detection wiring 13c is not broken, the piezoelectric element is the same as described with reference to FIG. It can be determined that the polarization state of the body 5 is an excessive state.

  If all of the current detection wirings 13a, 13b, and 13c are broken in the current detection wiring part 13 after the polarization process, the insulation of the piezoelectric element 1 is performed in the same manner as described with reference to FIG. Destruction is suspected.

  As described above, the resistance values of the current detection wirings 13a, 13b, and 13c may be the same value. Note that the resistance values of the current detection wirings 13a, 13b, and 13c may be different from each other. Further, the resistance value and the allowable current value of the current detection wirings 13a, 13b, 13c formed of the same wiring layer can be set to arbitrary values by setting the line width and length, respectively.

  FIG. 13 is a schematic plan view for explaining still another embodiment of the piezoelectric element. In FIG. 13, parts having the same functions as those in FIG.

  Compared with the embodiment shown in FIG. 1, the piezoelectric element 1 of this embodiment is provided with a current detection wiring portion 13 in the input wiring 11. Even when the current detection wiring portion 13 is provided in the input wiring 11, the current that has flowed through the piezoelectric body 5 during the polarization process is obtained as in the case where the current detection wiring portion 13 is provided in the ground wiring 9. Therefore, it is possible to easily determine whether the polarization state of the piezoelectric body 5 after the polarization treatment is excessive or insufficient.

  FIG. 14 is a schematic plan view for explaining still another embodiment of the piezoelectric element. In FIG. 14, parts having the same functions as those in FIG.

  The piezoelectric element 1 of this embodiment further includes a polarization processing wire 27 and a polarization processing electrode 29, as compared with the embodiment shown in FIG. The current detection wiring section 13 is disposed on the polarization processing wiring 27.

  The polarization processing wiring 27 is connected to the ground wiring 9. The polarization processing electrode 29 is connected to the polarization processing wiring 27. The current detection wiring portion 13 is formed in the polarization processing wiring 27 at a position between the ground wiring 9 and the polarization processing electrode 29.

  In this embodiment, a voltage is applied between the input electrode 25 and the polarization processing electrode 29 during the polarization processing. The current flows from the input electrode 25 to the polarization processing electrode 29 through the input wiring 11, the upper electrode 7, the piezoelectric body 5, the lower electrode 3, the ground wiring 9, and the polarization processing wiring 27. A current also flows through the current detection wiring portion 13 disposed in the polarization processing wiring 27. The current detection wiring unit 13 can detect the current that has flowed through the piezoelectric body 5 during the polarization process, as in the above embodiment. Therefore, the piezoelectric element 1 of this embodiment can easily determine whether the polarization state of the piezoelectric body 5 after the polarization process is excessive or insufficient.

  Note that the observation of the state of the current detection wiring portion 13 after the polarization treatment is not limited to the appearance observation, and can be electrically performed using the ground electrode 23 and the polarization treatment electrode 29. For example, by measuring a resistance value between the ground electrode 23 and the polarization processing electrode 29, or by measuring a current value when a current is passed between the ground electrode 23 and the polarization processing electrode 29, etc. The state of the current detection wiring part 13 after the polarization process can be electrically detected. Further, since no current flows through the polarization processing wiring 27 during the operation of the piezoelectric element 1, the resistance value of the polarization processing wiring 27 does not affect the operation of the piezoelectric element 1. Therefore, the resistance value of the current detection wiring portion 13 arranged in the polarization processing wiring 27 can be set to an arbitrary value, for example, a resistance value larger than the resistance value of the input wiring 11 and the resistance value of the ground wiring 9. it can.

  In this embodiment, the polarization processing wiring 27 is connected to the ground wiring 9 between the lower electrode 3 and the ground electrode 23, but the polarization processing wiring 27 is connected to the ground electrode 23 portion of the ground wiring 9. May be. In addition, the polarization processing wiring 27 may be connected to the lower electrode 3.

  The configuration in which the polarization processing wiring 27 and the polarization processing electrode 29 are provided and the current detection wiring section 13 is arranged in the polarization processing wiring 27 is the current detection wiring section on the input wiring 11 side shown in FIG. It is applicable also to the structure where 13 is arrange | positioned. The polarization processing wiring 27 may be connected between the polarization processing electrode 29 and the input wiring 11, may be connected between the polarization processing electrode 29 and the input electrode 25, or may be used for the polarization processing. It may be connected between the electrode 29 and the upper electrode 7.

  Further, one end of each of the current detection wirings 13a, 13b, 13c is directly connected to the ground wiring 9, and the other end of each of the current detection wirings 13a, 13b, 13c is directly connected to the polarization processing electrode 29. Good. That is, the polarization processing wiring 27 may be formed by the current detection wirings 13a, 13b, and 13c.

  FIG. 15 is a schematic plan view for explaining still another embodiment of the piezoelectric element. In FIG. 15, parts having the same functions as those in FIG.

  Compared with the embodiment shown in FIG. 1, the piezoelectric element 1 of this embodiment has a current detection wiring 13 a provided in the input wiring 11 among the current detection wirings 13 a, 13 b, 13 c constituting the current detection wiring section. It has been. The current detection wirings 13 b and 13 c are provided on the ground wiring 9.

  The current detection wiring 13a takes into consideration the resistance value of the portion 9a of the input wiring 11 to which the current detection wiring 13a is connected in parallel, and a current about the lower limit current value of the appropriate current value during the polarization process flows to the piezoelectric body 5. The resistance value and the line width (allowable current value) are set so that the wire breaks.

The current detection wiring 13b is set to have a resistance value and a line width (allowable current value) so that the current detection wiring 13b breaks when a current about the upper limit current value of the appropriate current value during the polarization process flows through the piezoelectric body 5.
The current detection wiring 13c has a resistance value and a line width (allowable current value) set so that the current detection wiring 13c breaks when a current having a current value that can detect an abnormality such as dielectric breakdown of the piezoelectric element 1 flows through the piezoelectric body 5. Yes.

  As described above, even when the plurality of current detection wirings 13a, 13b, and 13c are divided into the ground wiring 9 and the input wiring 11, the current detection wirings 13a, 13b, 13c can detect the current flowing through the piezoelectric body 5 during the polarization process. Therefore, the piezoelectric element 1 of this embodiment can easily determine whether the polarization state of the piezoelectric body 5 after the polarization process is excessive or insufficient.

  FIG. 16 is a schematic plan view for explaining still another embodiment of the piezoelectric element. In FIG. 16, parts having the same functions as those in FIG.

  In the piezoelectric element 1 of this embodiment, in the current detection wiring portion 13, the current detection wirings 13b and 13c are connected in parallel, and the current detection wiring 13a is connected in series to the current detection wirings 13b and 13c.

  In the current detection wiring 13a, in consideration of the resistance value of the portion 9a of the ground wiring 9 to which the current detection wiring 13a is connected in parallel, the current having the lower limit current value of the appropriate current value during the polarization process flows to the piezoelectric body 5. The resistance value and the line width (allowable current value) are set so as to break sometimes.

  The setting of the resistance value and the line width (allowable current value) of the current detection wirings 13b and 13c is the same as in the embodiment of FIG.

  As described above, even when the current detection wiring 13a is connected in series to the current detection wirings 13b and 13c, the current detection wirings 13a, 13b, and 13c are not subjected to polarization processing as in the above embodiment. The current flowing through the piezoelectric body 5 can be detected. Therefore, the piezoelectric element 1 of this embodiment can easily determine whether the polarization state of the piezoelectric body 5 after the polarization process is excessive or insufficient.

  Note that all of the current detection wirings 13a, 13b, and 13c may be connected in series. The setting method of each allowable current value of the current detection wirings 13a, 13b, and 13c in this case is the same as the setting method of the allowable current value of the current detection wiring 13a connected in parallel with the portion 9a of the ground wiring 9.

  The arrangement examples of the current detection wirings 13a, 13b, and 13c have been described with reference to FIGS. 1 and 12 to 16, but the configurations shown in FIGS. 1 and 12 to 16 may be combined or replaced. Is also possible.

  Further, the current detection wiring may include a configuration in which a current detection portion that is broken at a predetermined allowable current value and a resistance portion for adjusting the resistance value of the current detection wiring are connected in series. The resistance portion may be arranged at the upper stage (high potential side) of the current detection part, may be arranged at the rear stage (low potential side), or may be arranged at both the upper stage and the rear stage. . Such a configuration is particularly effective when it is difficult to design both the resistance ratio and the allowable current value in a plurality of current detection wirings.

  For example, a plurality of resistance portions having different resistance values due to different wiring widths, lengths, thicknesses, materials, and the like are provided in parallel. A plurality of current detection portions having different wiring widths, lengths, thicknesses, materials, and the like are provided at the subsequent stage of the resistance portion so that the allowable current values are different from each other. A current detection portion is connected in series to each resistance portion.

  FIG. 17 is a schematic plan view for explaining still another embodiment of the piezoelectric element. In FIG. 17, parts having the same functions as those in FIGS. 1 and 14 are denoted by the same reference numerals.

  The piezoelectric element 1 of this embodiment further includes a polarization processing wire 27 and a polarization processing electrode 29, as compared with the embodiment shown in FIG. The current detection wiring unit 13 also serves as the polarization processing wiring 27.

  The current detection wiring portion 13 that also serves as the polarization processing wiring 27 is connected between, for example, the input electrode 25 and the polarization processing wiring 27. The polarization processing electrode 29 is connected to the polarization processing wiring 27.

  The current detection wiring unit 13 includes current detection wirings 13a, 13b, and 13c. One end of each of the current detection wirings 13a, 13b, and 13c is connected to the input electrode 25. The other ends of the current detection wires 13a, 13b, and 13c are connected to the polarization processing electrode 29. The current detection wirings 13a, 13b, and 13c are connected in parallel between the input electrode 25 and the polarization processing electrode 29.

  The current detection wiring 13a includes a current detection portion 13a-1 and a pair of resistance portions 13a-2 and 13a-2 that are connected to both ends of the current detection portion 13a-1. Similarly, the current detection wiring 13b includes a current detection portion 13b-1 and a pair of resistance portions 13b-2 and 13b-2. Similarly, the current detection wiring 13c includes a current detection portion 13c-1 and a pair of resistance portions 13c-2 and 13c-2.

  The resistance value of the current detection wiring 13a is determined by the combined resistance of the current detection portion 13a-1 and the resistance portions 13a-2 and 13a-2. The resistance value of the current detection wiring 13b is determined by the combined resistance of the current detection portion 13b-1 and the resistance portions 13b-2 and 13b-2. The resistance value of the current detection wiring 13c is determined by the combined resistance of the current detection portion 13c-1 and the resistance portions 13c-2 and 13c-2. The resistance values of the current detection wirings 13a, 13b, and 13c may be different from each other, or any two or all of them may be the same.

  The current detection portions 13a-1, 13b-1, and 13c-1 are formed with a wiring width and a length that are cut at a desired allowable current value. The current detection portions 13a-1, 13b-1, and 13c-1 have different allowable current values due to, for example, different wiring widths. The permissible current values of the current detection portions 13a-1, 13b-1, and 13c-1 may have different values due to, for example, different wiring widths, lengths, thicknesses, materials, or combinations thereof. it can.

  The resistance portions 13a-2, 13b-2, and 13c-2 adjust the ratio of current flowing through the current detection portions 13a-1, 13b-1, and 13c-1 during the polarization process. The resistance portions 13a-2, 13b-2, and 13c-2 have different resistance values due to, for example, different wiring widths. The resistance values of the resistance portions 13a-2, 13b-2, and 13c-2 can have different values due to, for example, different wiring widths, lengths, thicknesses, materials, or combinations thereof.

  The current detection portion 13a-1 has a smaller allowable current value than the resistance portion 13a-2. The current detection portion 13b-1 has a smaller allowable current value than the resistance portion 13b-2. The current detection portion 13c-1 has a smaller allowable current value than the resistance portion 13c-2.

  In order to make the allowable current values different between the current detection portion 13a-1 and the resistance portion 13a-2, for example, the wiring width, length, thickness, material, or combination thereof may be different. In this embodiment, the current detection portion 13a-1 and the resistance portion 13a-2 have different allowable current values due to the different wiring widths. The same applies to the current detection portion 13b-1 and the resistance portion 13b-2, and the current detection portion 13c-1 and the resistance portion 13c-2.

The detection wiring portion 13 a-1 is set with an allowable current value so that the detection wiring portion 13 a-1 is broken when a current that is about the lower limit current value of the appropriate current value during the polarization process flows through the piezoelectric body 5.
The current detection portion 13b-1 is set to have an allowable current value so that the current detection portion 13b-1 breaks when a current of about the upper limit current value of the appropriate current value during the polarization process flows into the piezoelectric body 5.
The current detection portion 13 c-1 is set with an allowable current value so that the current detection portion 13 c-1 is broken when a current having a current value that can detect an abnormality such as dielectric breakdown of the piezoelectric element 1 flows through the piezoelectric body 5.

  In this embodiment, a voltage is applied between the polarization processing electrode 29 and the ground electrode 23 during the polarization processing. The current is grounded from the polarization processing electrode 29 through the current detection wiring section 13 (polarization processing wiring 27), the input electrode 25, the input wiring 11, the upper electrode 7, the piezoelectric body 5, the lower electrode 3, and the ground wiring 9. It flows to the electrode 23.

  The current detection wiring unit 13 can detect the current that has flowed through the piezoelectric body 5 during the polarization process, as in the above embodiment. Therefore, the piezoelectric element 1 of this embodiment can easily determine whether the polarization state of the piezoelectric body 5 after the polarization process is excessive or insufficient.

The observation of the state of the current detection wiring portion 13 after the polarization process is not limited to the appearance observation, but is electrically performed using the input electrode 25 and the polarization process electrode 29 as in the embodiment shown in FIG. It can be carried out.
Further, since no current flows through the current detection wiring section 13 (polarization processing wiring 27) during the operation of the piezoelectric element 1, the resistance value of the current detection wiring section 13 does not affect the operation of the piezoelectric element 1. Therefore, the resistance value of the current detection wiring portion 13 can be set to an arbitrary value, for example, a resistance value larger than the resistance value of the input wiring 11 or the resistance value of the ground wiring 9.

  In this embodiment, the current detection wiring section 13 also serves as the polarization processing wiring 27, but the current detection wiring section 13 is arranged in the polarization processing wiring 27 as in the embodiment shown in FIG. 14. You may do it.

  In this embodiment, the current detection wiring portion 13 is connected to the input electrode 25, but the current detection wiring portion 13 may be connected to the input wiring 11 or connected to the upper electrode 7. Also good. Further, the current detection wiring portion 13 may be connected to the lower electrode 3, may be connected to the ground wiring 9, or may be connected to the ground electrode 23.

  In this embodiment, resistance portions 13a-2, 13b-2, and 13c-2 are provided corresponding to the current detection portions 13a-1, 13b-1, and 13c-1, but one resistance portion is provided. A plurality of current detection portions may be connected in parallel. For example, the current detection portions 13a-1 and 13b-1 may be connected in parallel to the resistance portion 13b-2 without providing the resistance portion 13a-2. In this configuration, it goes without saying that the resistance value and the allowable current value are appropriately set for the current detection portions 13a-1, 13b-1, 13c-1 and the resistance portions 13b-2, 13c-2.

  In this embodiment, the current detection wiring 13a includes resistance portions 13a-2 at both ends of the current detection portion 13a-1, but the current detection wiring 13a has only one end of the current detection portion 13a-1. The resistor portion 13a-2 may be provided. The same applies to the current detection wirings 13b and 13c.

  In addition, the current detection wiring in which the resistance part is arranged before the current detection part, the current detection wiring in which the resistance part is arranged after the current detection part, and the current in which the resistance part is arranged in the upper and lower stages of the current detection part A plurality or all of the current detection wirings among the detection wirings may be mounted together. Moreover, the current detection wiring provided with the current detection part and the resistance part and the current detection wiring not provided with the current detection part and the resistance part may be mounted together.

  The configuration of FIG. 17 in which the current detection wiring includes a current detection portion and a resistance portion can be combined with or replaced with the configuration shown in FIGS. 1 and 12 to 16.

  As mentioned above, although the Example of this invention was described, the numerical value, material, arrangement | positioning, number, etc. in the said Example are examples, This invention is not limited to these, It was described in the claim Various modifications are possible within the scope of the present invention.

  For example, in the above-described embodiment, it is described that a circuit abnormality or the like can be detected by breaking the current detection wiring 13c. However, the piezoelectric element of the present invention includes at least a current detection wiring that breaks when a current with a lower limit current value of an appropriate current value during polarization treatment flows through the piezoelectric body, and a current with an upper limit current value of an appropriate current value. It is only necessary to have a current detection wiring that breaks when the current flows. Thereby, the piezoelectric element of this invention can discriminate | determine the excess and deficiency of the polarization state in the piezoelectric material after polarization processing.

  Moreover, in the said Example, although the line width of current detection wiring 13a, 13b, 13c is respectively constant, in the piezoelectric element of this invention, the line width of current detection wiring does not need to be constant.

  Further, the above embodiment includes a configuration in which the current detection wirings 13 a, 13 b, 13 c use the entire line width of the ground wiring 9 in the current detection wiring unit 13. However, in the piezoelectric element of the present invention, the current detection wiring may be configured to use a part of the line width of the first wiring or the second wiring, or connected in parallel to the first wiring or the second wiring. It may be configured.

  In the piezoelectric element of the present invention, the means for making the allowable current values different from each other for the plurality of current detection wires is not limited to the method of making the wire widths and lengths of the wires different. For example, the plurality of current detection wirings may have different thicknesses. Further, the plurality of current detection wirings may be formed of a plurality of materials having different electric resistivity. Further, the plurality of current detection wirings may be formed of a plurality of wiring layers. In the piezoelectric element of the present invention, means for making the allowable current values different for the plurality of current detection wirings is not particularly limited.

  Further, if three or more current detection wirings having different allowable current values that are broken when current flowing in or around the appropriate current value range during the polarization process flows to the piezoelectric body, more detailed piezoelectric body The polarization state of can be grasped. In this case, the more detailed the polarization state of the piezoelectric body can be grasped as the number of current detection wirings having different allowable current values is increased.

  In the above embodiment, the lower electrode 3 is connected to the ground potential and the input voltage is supplied to the upper electrode 7. However, the piezoelectric element of the present invention is not limited to this. In the piezoelectric element of the present invention, either the first electrode or the second electrode may be connected to the high potential side (for example, input voltage).

  In the above embodiment, the piezoelectric element 1 is mounted on the actuator substrate 104 of the droplet discharge head 101, but the apparatus to which the piezoelectric element of the present invention is applied is not limited to this. The piezoelectric element according to the present invention is a piezoelectric element having any configuration as long as the piezoelectric element includes the first electrode, the first wiring, the second electrode, the second wiring, and the piezoelectric body. Even applicable.

  Further, the droplet discharge head of the present invention is not limited to the configuration of the droplet discharge head 101. The droplet discharge head of the present invention includes a nozzle layer having a plurality of nozzle holes, a flow path layer that forms a liquid chamber communicating with the nozzle holes, and a piezoelectric device that generates a pressure in the fluid flowing through the liquid chamber via a vibration plate. Any droplet discharge head having any configuration can be applied as long as the droplet discharge head includes an element.

  In the droplet discharge head of the present invention, a plurality of nozzle holes may be arranged for one liquid chamber.

1 Piezoelectric element 3 Lower electrode (first electrode or second electrode)
5 Piezoelectric body 7 Upper electrode (second electrode or first electrode)
9 Grounding wiring (first wiring or second wiring)
11 Input wiring (second wiring or first wiring)
13a, 13b, 13c Current detection wiring 101 Droplet discharge head 103 Nozzle plate (nozzle layer)
109 Nozzle hole 110 Liquid chamber 115 Vibration plate 201 Liquid cartridge

Japanese Patent Laid-Open No. 60-60788

Claims (4)

A first electrode;
A first wiring electrically connected to the first electrode;
A second electrode;
A second wiring electrically connected to the second electrode;
A piezoelectric body disposed between the first electrode and the second electrode;
A piezoelectric element comprising: a plurality of current detection wirings arranged in the first wiring, the second wiring, or both, and having different allowable current values. A droplet discharge head comprising a nozzle layer having a nozzle hole, a flow path layer forming a liquid chamber communicating with the nozzle hole, and a piezoelectric element that generates a pressure in the fluid flowing in the liquid chamber via a vibration plate In
The droplet discharge head according to claim 1, wherein the piezoelectric element is a piezoelectric element according to claim 1. In a liquid cartridge in which a droplet discharge head that discharges droplets and a liquid tank that supplies liquid to the droplet discharge head are integrated,
The liquid cartridge according to claim 2, wherein the liquid droplet ejection head is the liquid droplet ejection head according to claim 2. In a droplet discharge recording apparatus equipped with a droplet discharge head for discharging droplets,
A droplet discharge recording apparatus according to claim 2, wherein the droplet discharge head is the droplet discharge head according to claim 2.