JP2013188929A - Performance inspection method of piezoelectric actuator and liquid ejection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect performance of a piezoelectric actuator by using a resonance frequency without enlarging an apparatus.SOLUTION: In a flow path unit 21, inspection spaces 17 are provided at adjacent positions of a plurality of pressure chambers 10 in a scanning direction respectively. In a piezoelectric actuator 22, the part that overlaps with the pressure chamber 10, and the part that overlaps with the inspection space 17 become a drive part 22a and an inspection part 22b respectively. An individual electrode 45 of the drive part 22a and an inspection electrode 46 of the inspection part 22b are continued through a conduction part 47. An inspection electrode 46 is applied voltage and the frequency is changed by contacting a probe 63 connected with a voltage applying device 62 to the individual electrode 45. Then, the frequency when the peak of current value Ie is obtained is detected from a value V of the applied voltage and a current value Ie output from a common electrode 44 detected by a current detecting device 61 as a resonance frequency of the inspection part 22b.

Description

  The present invention relates to a performance inspection method for a piezoelectric actuator used in a liquid ejecting apparatus that ejects liquid from a nozzle, and a liquid ejecting apparatus that ejects liquid from a nozzle.

  In the ink jet head described in Patent Document 1, the cavity unit includes a nozzle, an ink flow path such as a pressure chamber communicating with the nozzle, a space provided separately from the ink flow path, a pressure chamber, and the space described above. And a piezoelectric layer as a vibrating plate. In addition, the piezoelectric actuator spans the first and second piezoelectric layers stacked on the upper surface of the piezoelectric layer, and a plurality of pressure chambers and the space between the first and second piezoelectric layers. Common electrodes formed continuously, a plurality of individual electrodes respectively formed on the upper surface of the first piezoelectric layer facing the pressure chamber, the lower surface of the second piezoelectric layer, the first piezoelectric layer and the first piezoelectric layer And a driving electrode for inspection provided respectively in a portion overlapping the space between the two piezoelectric layers and a portion overlapping the space on the upper surface of the first piezoelectric layer.

  In an ink jet in which a cavity unit and a piezoelectric actuator are stacked as described in Patent Document 1, variations in the thickness of the piezoelectric layer as the diaphragm, variations in the thickness of the first and second piezoelectric layers, The drive characteristics of the piezoelectric actuator may fluctuate due to variations in the thickness of the adhesive that joins the piezoelectric actuator. Therefore, in Patent Document 1, the first and second piezoelectric elements of the piezoelectric actuator are used by using the piezoelectric layer as the diaphragm, the portions of the first and second piezoelectric layers overlapping the voids, and the driving electrode for inspection. The pass / fail of the piezoelectric actuator is determined by measuring the capacitance of the layer, or by measuring the resonance frequency of the portion of the piezoelectric actuator that overlaps the void.

JP 2010-155407 A

  Here, in Patent Document 1, when the pass / fail of the piezoelectric actuator is determined by measuring the resonance frequency of the portion of the piezoelectric actuator that overlaps the void, the inspection electrode is caused to resonate the portion of the piezoelectric actuator. It is necessary to apply a voltage for At this time, for example, a voltage is applied to the inspection electrode by bringing a probe connected to a power source or the like into contact with a pad that is electrically connected to the inspection electrode. Note that the probe is not in direct contact with the test drive electrode, but the probe is brought into contact with the pad that is electrically connected to the test electrode. The voltage is applied to the test electrode by bringing the probe directly into contact with the test drive electrode. Then, the resonance of the part of the piezoelectric actuator is hindered by the probe, and the resonance frequency cannot be measured accurately.

  In this case, it is necessary to form a pad on the upper surface of the first piezoelectric layer, which is electrically connected to the test drive electrode, for contacting the probe. In this case, if a space for providing such a pad is provided on the upper surface of the first piezoelectric layer, the size of the piezoelectric actuator is increased.

  An object of the present invention is to provide a piezoelectric actuator performance inspection method capable of detecting the resonance frequency by detecting the resonance frequency without increasing the size of the piezoelectric actuator, and without increasing the size of the piezoelectric actuator. It is an object of the present invention to provide a liquid ejection device capable of detecting a resonance frequency and performing a performance inspection of a piezoelectric actuator.

  According to a first aspect of the present invention, there is provided a liquid discharge apparatus including a flow path unit including a nozzle, a pressure chamber communicating with the nozzle, and an inspection space provided separately from the pressure chamber, the pressure chamber, and the inspection chamber. A first layer covering the space; and a piezoelectric material, disposed on a surface of the first layer opposite to the pressure chamber, and continuously across the pressure chamber and the inspection space. The extended second layer, the driving electrode formed in a portion overlapping the pressure chamber on the surface of the second layer opposite to the first layer, and the inspection space of the piezoelectric layer overlap And a piezoelectric actuator having an inspection electrode electrically connected to the driving electrode.

  According to a seventh aspect of the present invention, there is provided a piezoelectric actuator performance inspection method comprising a nozzle, a flow path unit having a pressure chamber communicating with the nozzle, and a piezoelectric actuator that applies pressure to the liquid in the pressure chamber. A method for inspecting performance of a piezoelectric actuator in a liquid ejection apparatus, wherein the flow path unit further includes an inspection space provided separately from the pressure chamber, and the piezoelectric actuator includes the pressure chamber and the inspection space. A first layer covering the first layer and a piezoelectric material, disposed on a surface of the first layer opposite to the pressure chamber, and continuously extending across the pressure chamber and the inspection space. A second electrode, a driving electrode formed on a portion of the second layer opposite to the first layer on the surface overlapping the pressure chamber, and the inspection space of the second layer, Formed in overlapping parts A portion overlapping the inspection space of the piezoelectric actuator by applying a voltage to the inspection electrode and changing the frequency of the voltage. The resonance frequency detection step of detecting the resonance frequency of the inspection unit and the resonance frequency detected in the resonance frequency detection process, the drive unit that is a portion overlapping the pressure chamber of the piezoelectric actuator has a predetermined performance. A determination step of determining whether or not there is a voltage, and in the resonance frequency detection step, by bringing a probe for applying a voltage to the inspection electrode into contact with the driving electrode, the voltage is applied to the inspection electrode. It is characterized by applying.

  According to these inventions, the probe is brought into contact with the drive electrode, and the voltage is applied to the test electrode that is electrically connected to the drive electrode, whereby the resonance frequency of the test section that overlaps the test space of the piezoelectric actuator is reduced. Based on the detected resonance frequency, it is possible to determine whether or not the drive unit that is a portion overlapping the pressure chamber of the piezoelectric actuator has a predetermined performance.

  At this time, since the driving electrode is used as a pad for contacting the probe, it is not necessary to provide a dedicated pad separately, and the enlargement of the piezoelectric actuator can be suppressed. In particular, when the piezoelectric actuator has a plurality of drive units, and an inspection unit is provided for each drive unit, the size of the piezoelectric actuator is significantly increased by providing a separate dedicated pad. However, according to the present invention, in such a case, an increase in size of the piezoelectric actuator can be particularly effectively suppressed by using the driving electrode as a pad.

  The liquid ejection device according to a second aspect of the present invention is the liquid ejection device according to the first aspect, wherein the size of the pressure chamber and the size of the inspection space are viewed from the stacking direction of the flow path unit and the piezoelectric actuator. Are different from each other, the resonance frequency of the driving portion that is a portion overlapping the pressure chamber of the piezoelectric actuator is different from the resonance frequency of the inspection portion that is a portion overlapping the inspection space of the piezoelectric actuator. It is characterized by being.

  The piezoelectric actuator performance inspection method according to an eighth aspect of the present invention is the piezoelectric actuator performance inspection method according to the seventh aspect of the present invention, wherein the pressure chamber size and the piezoelectric chamber are viewed from the stacking direction of the flow path unit and the piezoelectric actuator. The resonance frequency of the driving unit and the resonance frequency of the inspection unit are different from each other because the size of the inspection space is different.

  According to these inventions, since the resonance frequency of the drive unit is different from the resonance frequency of the inspection unit, it is possible to prevent the drive unit from resonating when the inspection unit is resonated. Thereby, when detecting the resonant frequency of an inspection part, it can prevent that the crack will enter into the part which forms the drive part of the 2nd layer.

  A performance inspection method for a piezoelectric actuator according to a ninth invention is the performance inspection method for a piezoelectric actuator according to the seventh or eighth invention, wherein the resonance frequency detection step includes a resonance frequency of the inspection section, and The frequency of the voltage applied to the inspection electrode is changed within a range not including the resonance frequency of the driving unit.

  According to the present invention, it is possible to reliably prevent the drive unit from resonating when detecting the resonance frequency of the inspection unit. The resonance frequency of the drive unit and the inspection unit may estimate the size and the pressure chamber and the inspection space, etc. The thickness of the first layer and the second layer, a value of how much in advance . Therefore, if the frequency of the voltage applied to the inspection electrode is changed in the vicinity of the estimated resonance frequency, it is applied to the inspection electrode in a range that includes the resonance frequency of the inspection section and does not include the resonance frequency of the drive section. The frequency of the voltage to be changed can be changed.

  A piezoelectric actuator performance inspection method according to a tenth invention is the piezoelectric actuator performance inspection method according to any one of the seventh to ninth inventions, wherein the inspection electrode is the first layer of the second layer. Bumps are formed on the surface opposite to the layer, and after the resonance frequency detecting step, bumps for connecting to the wiring member are formed on the surface opposite to the first layer of the inspection electrode. A bump forming step is further provided.

  According to the present invention, since the inspection electrode is used as a connection terminal on which a bump for connecting to the wiring member is formed after detecting the resonance frequency of the inspection portion, there is no need to provide a separate connection terminal, An increase in size of the piezoelectric actuator can be suppressed. In particular, when the piezoelectric actuator has a plurality of drive units and an inspection unit is provided for each of the drive units, if the connection terminal is provided separately, the piezoelectric actuator is significantly increased in size. However, according to the present invention, in such a case, the increase in size of the piezoelectric actuator can be particularly effectively suppressed by using the inspection electrode as the connection terminal.

  A liquid ejection apparatus according to a third aspect is the liquid ejection apparatus according to the first or second aspect, wherein the inspection space is circular when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. It is characterized by.

  The piezoelectric actuator performance inspection method according to an eleventh aspect of the invention is the piezoelectric actuator performance inspection method according to any of the seventh to tenth aspects, wherein the inspection space is a stacking direction of the flow path unit and the piezoelectric actuator. It is characterized by being circular as viewed from the top.

  According to these inventions, the peak of the current value output when the frequency of the voltage applied to the inspection electrode is changed to detect the resonance frequency of the inspection portion becomes sharp. Therefore, it is easy to detect the resonance frequency of the inspection unit.

  A liquid ejection device according to a fourth invention is the liquid ejection device according to any one of the first to third inventions, wherein the shape of the inspection space is viewed from the stacking direction of the flow path unit and the piezoelectric actuator. And the shape of the inspection electrode is similar.

  A piezoelectric actuator performance inspection method according to a twelfth aspect of the invention is the piezoelectric actuator performance inspection method according to any of the seventh to eleventh aspects of the invention, as viewed from the stacking direction of the flow path unit and the piezoelectric actuator. The shape of the inspection space and the shape of the inspection electrode are similar.

  According to these inventions, the peak of the current value output when the frequency of the voltage applied to the inspection electrode is changed to detect the resonance frequency of the inspection portion becomes sharp. Therefore, it is easy to detect the resonance frequency of the inspection unit.

  The liquid ejection device according to a fifth aspect of the invention is the liquid ejection device according to any one of the first to fourth aspects of the invention, as viewed from the stacking direction of the flow path unit and the piezoelectric actuator, It is smaller than the inspection space.

  A piezoelectric actuator performance inspection method according to a thirteenth aspect of the invention is the piezoelectric actuator performance inspection method according to any of the seventh to twelfth aspects of the invention, as viewed from the stacking direction of the flow path unit and the piezoelectric actuator. The inspection electrode is smaller than the inspection space.

  According to these inventions, the amount of deformation of the inspection part when the inspection part is resonated can be increased. Therefore, it is easy to detect the resonance frequency of the inspection unit.

  According to a fourteenth aspect of the piezoelectric actuator performance inspection method, in the performance inspection of the piezoelectric actuator according to the eighth or ninth aspect, the resonance frequency of the inspection section in the primary vibration mode is the primary vibration of the driving section. A resonance frequency in the mode and a resonance frequency in the secondary vibration mode, wherein the resonance frequency in the primary vibration mode of the inspection unit is detected in the resonance frequency detection step. .

  According to the present invention, the resonance frequency in the primary vibration mode of the inspection unit is a frequency between the resonance frequency in the primary vibration mode of the drive unit and the resonance frequency in the secondary vibration mode. As a result, the drive unit does not resonate by detecting the resonance frequency in the primary vibration mode.

  A liquid ejection apparatus according to a sixth aspect of the invention is the liquid ejection apparatus according to any one of the first to fifth aspects, wherein the plurality of pressure chambers are arranged along one direction, and the inspection space is In the direction perpendicular to the one direction, the pressure chamber is provided at a position adjacent to the pressure chamber.

  The piezoelectric actuator performance inspection according to a fifteenth aspect of the invention is the piezoelectric actuator performance inspection method according to any of the seventh to fourteenth aspects of the invention, wherein the flow path unit includes a plurality of the pressure chambers, A plurality of driving electrodes corresponding to the plurality of pressure chambers, wherein the plurality of pressure chambers are arranged along one direction, and the inspection space is in a direction perpendicular to the one direction. The pressure chamber is provided at a position adjacent to at least one of the plurality of pressure chambers.

  According to these inventions, since the inspection space is provided at a position adjacent to the pressure chamber in a direction orthogonal to the one direction in which the plurality of pressure chambers are arranged, even when the inspection space is formed, The arrangement interval does not increase.

  According to the present invention, the probe is brought into contact with the drive electrode and a voltage is applied to the test electrode that is electrically connected to the drive electrode, whereby the resonance frequency of the test section that overlaps the test space of the piezoelectric actuator is reduced. Based on the detected resonance frequency, it is possible to determine whether or not the drive unit that is a portion overlapping the pressure chamber of the piezoelectric actuator has a predetermined performance.

  At this time, since the driving electrode is used as a pad for contacting the probe, it is not necessary to provide a dedicated pad separately, and the enlargement of the piezoelectric actuator can be suppressed. In particular, when the piezoelectric actuator has a plurality of drive units, and an inspection unit is provided for each drive unit, the size of the piezoelectric actuator is significantly increased by providing a separate dedicated pad. However, according to the present invention, in such a case, an increase in size of the piezoelectric actuator can be particularly effectively suppressed by using the driving electrode as a pad.

1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. It is a top view of the inkjet head of FIG. It is the III-III sectional view taken on the line of FIG. 3 is a flowchart illustrating a manufacturing process of a printer. It is a figure which shows a state when detecting the resonant frequency of a test | inspection part. It is a figure which shows the relationship between the frequency of the voltage applied to a drive electrode and a test | inspection electrode, and the output electric current. It is a flowchart which shows the process of determining the performance of the piezoelectric actuator of FIG. It is a figure equivalent to FIG. 2 in one modification. FIG. 9 is a view corresponding to FIG. 3 in the modification of FIG. 8.

  Hereinafter, preferred embodiments of the present invention will be described.

  As shown in FIG. 1, the printer 1 according to the present embodiment includes a carriage 2, an inkjet head 3, a paper transport roller 4, and the like. The carriage 2 reciprocates in the scanning direction along the guide bar 5. The ink jet head 3 is mounted on the carriage 2 and ejects ink from a plurality of nozzles 15 (see FIG. 2) formed on the lower surface thereof. The paper transport roller 4 transports the recording paper P in the paper feed direction orthogonal to the scanning direction.

  In the printer 1, printing is performed on the recording paper P by ejecting ink from the inkjet head that reciprocates in the scanning direction together with the carriage 2 onto the recording paper P conveyed in the paper feeding direction by the paper conveying roller 4. . Further, the recording paper P for which printing has been completed is discharged by the paper transport roller 4.

  Next, the inkjet head 3 will be described. As shown in FIGS. 2 and 3, the inkjet head 3 applies pressure to the flow path unit 21 in which the ink flow paths such as the nozzle 15 and the pressure chamber 10 described later are formed, and the ink in the pressure chamber 10. The piezoelectric actuator 22 is provided.

  The flow path unit 21 is formed by bonding four plates 31 to 34 to each other with an adhesive in a state where the plates 31 to 34 are stacked in this order from above. Here, of the four plates 31 to 34, the three plates 31 to 33 excluding the plate 34 disposed at the lowermost position are made of a metal material such as stainless steel. The plate 34 is made of a synthetic resin material. Alternatively, the plate 34 may be made of the same metal material as the plates 31 to 33.

  A plurality of pressure chambers 10 are formed in the plate 31. The pressure chamber 10 has a substantially rectangular planar shape whose longitudinal direction is the scanning direction. The plurality of pressure chambers 10 are arranged in the paper feed direction to form a pressure chamber row 9, and the pressure chamber rows 9 are arranged in two rows in the scanning direction on the plate 31. Yes. In the plate 31, an inspection space 17 having a substantially circular planar shape is formed in a portion adjacent to the outside of each pressure chamber 10 in the scanning direction.

  In the plate 32, substantially circular through holes 12 and 13 a are formed in portions overlapping the outer end and inner end of the pressure chamber 10 in the longitudinal direction, respectively. A manifold channel 11 is formed in the plate 33. The manifold channel 11 extends in two rows in the paper feed direction along the pressure chamber row 9 and overlaps substantially half of the pressure chamber 10 on the through hole 12 side in the scanning direction. In addition, the manifold channels 11 extending in two rows communicate with each other at the base end portion, and ink is supplied to the manifold channel 11 from the ink supply port 8 communicating with the base end portion. Further, the plate 33 is formed with a substantially circular through hole 13b at a portion overlapping the through hole 13a. In the plate 34, the nozzle 15 is formed in a portion overlapping the through hole 13b.

  In the flow path unit 21 as described above, the manifold flow path 11 communicates with the plurality of pressure chambers 10 through the through holes 12, and each pressure chamber 10 is formed by the corresponding through holes 13a and 13b. It communicates with the nozzle 15 via the descender flow path 13. As a result, the flow path unit 21 is formed with a manifold flow path 11 and a plurality of individual ink flow paths from the outlet of the manifold flow path 11 to the nozzle 15 via the pressure chamber 10. The inspection space 17 is an independent space that does not communicate with these ink flow paths.

  The piezoelectric actuator 22 includes an ink separation layer 41, a ceramic layer 42, a piezoelectric layer 43, a common electrode 44, a plurality of individual electrodes 45, a plurality of inspection electrodes 46, and the like.

  The ink separation layer 41 is a plate-like member made of a metal material such as stainless steel, and is bonded to the upper surface of the plate 31 with an adhesive so as to cover the pressure chamber 10 and the inspection space 17. The ink separation layer 41 is for preventing ink in the pressure chamber 10 from coming into contact with the ceramic layer 42. The ceramic layer 42 is made of a piezoelectric material mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate, and is bonded to the upper surface of the ink separation layer 41 by an adhesive 26. The piezoelectric layer 43 is made of the same piezoelectric material as the ceramic layer 42, and is disposed on the upper surface of the ceramic layer 42. The ceramic layer 42 and the piezoelectric layer 43 continuously extend across the plurality of pressure chambers 10 and the plurality of inspection spaces 17.

  Unlike the piezoelectric layer 43, the ceramic layer 42 may be made of a material other than the piezoelectric material. Further, instead of the ink separation layer 41 and the ceramic layer 42 laminated on each other, one member or three or more members laminated on each other may be arranged.

  Here, in the ink jet head 3, an adhesive is also present between the plates 31 to 34 and between the plate 31 and the ink separation layer 41, but FIG. The adhesives other than the adhesive 26 are not shown.

  The common electrode 44 is formed between the ceramic layer 42 and the piezoelectric layer 43 and extends over almost the entire area thereof. The common electrode 44 is led out to a surface electrode 38 formed on the upper surface of the piezoelectric layer 43 through a through hole 39 formed in the piezoelectric layer 43. A bump 37 protruding upward from the upper surface of the piezoelectric layer 43 is formed on the upper surface of the surface electrode 38. The bump 37 is made of a conductive material and is connected to the wiring 51 of the FPC 50 disposed above the piezoelectric actuator 22. A driver IC (not shown) is connected to the wiring 51, and the common electrode 44 is connected to the driver IC via the wiring 51, the bump 37, the surface electrode 38, and the through hole 39. The common electrode 44 is always held at the ground potential by the driver IC.

  The plurality of individual electrodes 45 have a substantially rectangular planar shape that is slightly smaller than the pressure chamber 10, and are arranged on a portion of the upper surface of the piezoelectric layer 43 that overlaps with a substantially central portion of the plurality of pressure chambers 10. The plurality of inspection electrodes 46 have a substantially circular planar shape that is slightly smaller than the inspection space 17, and are arranged in a portion overlapping the substantially central portion of the plurality of inspection spaces 17 on the upper surface of the piezoelectric layer 43. ing.

  Here, the common electrode 44, the plurality of individual electrodes 45, and the plurality of inspection electrodes 46 are arranged in this way, and are sandwiched between the individual electrodes 45 and the common electrode 44 of the piezoelectric layer 43. The portions sandwiched between the inspection electrodes 46 and the common electrode 44 are polarized in the thickness direction.

  A plurality of conduction portions 47 are provided on the upper surface of the piezoelectric layer 43. The plurality of conducting portions 47 are disposed between the corresponding individual electrodes 45 and the inspection electrodes 46 and extend in the scanning direction to electrically connect the individual electrodes 45 and the inspection electrodes 46.

  A bump 48 protruding upward from the upper surface of the piezoelectric layer 43 is formed on the upper surface of the inspection electrode 46. The bump 48 is made of a conductive material and is connected to the wiring 51 of the FPC 50 disposed above the piezoelectric actuator 22. A driver IC (not shown) is connected to the wiring 51, and the plurality of individual electrodes 45 are connected to the driver IC via the wiring 51, the bump 48, and the conduction portion 47, respectively. The plurality of individual electrodes 45 are selectively given either a ground potential or a drive potential by a driver IC.

  In the piezoelectric actuator 22 configured as described above, the portions that overlap with the plurality of pressure chambers 10 serve as driving units 22a for applying pressure to the ink in the pressure chambers 10, respectively. Further, a portion overlapping the inspection space 17 is an inspection unit 22b for inspecting the performance of the corresponding drive unit 22a.

  Here, a method for ejecting ink from the nozzle 15 by driving the piezoelectric actuator 22 in the inkjet head 3 will be described. In the piezoelectric actuator 22, all the individual electrodes 45 are previously held at the ground potential by the driver IC. When ink is ejected from a certain nozzle 15, the potential of the corresponding individual electrode 45 is switched to the driving potential. Then, a voltage is applied to the portion of the piezoelectric layer 43 sandwiched between the individual electrode 45 and the common electrode 44, and an electric field parallel to the polarization direction is generated in this portion of the piezoelectric layer. The electric field causes this portion of the piezoelectric layer 43 to contract in the horizontal direction orthogonal to the polarization direction, and the portion of the ink separation layer 41, the ceramic layer 42, and the piezoelectric layer 43 that overlaps the pressure chamber 10 as a whole. The volume of the pressure chamber 10 is reduced by being deformed so as to protrude to the side. As a result, the pressure of the ink in the pressure chamber 10 rises, and the ink is ejected from the nozzle 15 communicating with the pressure chamber 10.

  Next, a manufacturing method of the printer 1 will be described with reference to the flowchart of FIG. In order to manufacture the printer 1, first, the inkjet head 3 is manufactured (step S101, hereinafter, simply referred to as S101).

  Next, in the inkjet head 3 manufactured in S101, the resonance frequency of the inspection unit 22b of the piezoelectric actuator 22 is detected (S102). Specifically, for example, as shown in FIG. 5, a current detection device 61 is connected to the common electrode 44, and a probe 63 connected to a voltage application device 62 is connected to an individual electrode 45 corresponding to a certain inspection electrode 46. Contact. Then, the voltage application device 62 applies a voltage from the probe 63 to the inspection electrode 46 via the individual electrode 45 and the conduction portion 47, and sequentially changes the frequency, and the current detection device 61 outputs the voltage from the common electrode 44. The detected current value Ie is detected.

  At this time, as shown in FIG. 6, when the frequency of the voltage applied to the inspection electrode 46 becomes the resonance frequency of the inspection unit 22b, the frequency is a frequency other than the resonance frequency of the inspection unit 22b. Also, the current value Ie output from the common electrode 44 becomes extremely large. Using this fact, when the peak of the current value Ie is obtained, the frequency of the voltage applied to the inspection electrode 46 is detected as the resonance frequency of the inspection unit 22b.

  Here, as described above, when the frequency of the voltage applied to the individual electrode 45 becomes the resonance frequency of the drive unit 22a, the frequency of the drive unit 22a is the drive unit as shown in FIG. The current value Id output from the common electrode 44 becomes extremely larger than when the frequency is other than the resonance frequency of 22a.

  In the present embodiment, since the inspection space 17 has a different planar shape from the pressure chamber 10, the resonance frequency of the inspection portion 22b is different from the resonance frequency of the drive portion 22a. More specifically, as shown in FIG. 6, the resonance frequency Fe1 in the primary vibration mode of the inspection unit 22b is approximately equal to the resonance frequency Fd1 in the primary vibration mode of the drive unit 22a and the resonance frequency Fd2 in the secondary vibration mode. It is an intermediate frequency.

  Specifically, for example, in the flow path unit 21, the planar shape of the pressure chamber 10 is a substantially rectangular shape having a length in the scanning direction of about 800 μm and a length in the paper feed direction of about 350 μm. The planar shape of the space 17 is a substantially circular shape with a diameter of about 440 μm. In the piezoelectric actuator 22, the thickness of the ink separation layer 41 is about 10 μm, and the thicknesses of the ceramic layer 42 and the piezoelectric layer 43 are each about 20 μm. In this case, the resonance frequencies Fd1 and Fd2 in the primary vibration mode and the secondary vibration mode of the drive unit 22a are about 1 MHz and about 1.5 MHz, respectively. On the other hand, the resonance frequency in the primary vibration mode of the inspection unit 22b is about 1.25 MHz.

  In this embodiment, the resonance frequency in the primary vibration mode is detected as the resonance frequency of the inspection unit 22b.

  Further, as described above, the value of the resonance frequency of the drive unit 22a is estimated in advance depending on the shape and size of the pressure chamber 10, the thickness of the ink separation layer 41, the ceramic layer 42, and the piezoelectric layer 43, and the like. can do. On the other hand, it is possible to estimate in advance how much the resonance frequency of the inspection unit 22b will be based on the shape and size of the inspection space 17, the thickness of the ink separation layer 41, the ceramic layer 42, and the piezoelectric layer 43, and the like. it can.

  Therefore, as described above, when the resonance frequency of the inspection unit 22b is detected by changing the frequency of the voltage applied to the inspection electrode 46, the resonance frequency of the inspection unit 22b is included and the drive unit 22a. The frequency is changed within a range where it is estimated that the resonance frequency is not included. Specifically, for example, the frequency of the voltage applied to the inspection electrode 46 is changed in the vicinity of the estimated resonance frequency of the inspection unit 22b.

  By the above-described method, the resonance frequency is detected in order for all the inspection units 22b. Then, it is determined whether or not the drive unit 22a has a predetermined performance according to the detected resonance frequency (S103).

  The process in S103 will be described with reference to the flowchart of FIG. In S103, it is determined whether or not the resonance frequencies Fe1 of the plurality of inspection units 22b detected in S102 are within a predetermined range R (S201). If the resonance frequency of any of the inspection units 22b is out of the predetermined range R (S201: NO), the inkjet head 3 having the piezoelectric actuator 22 is discarded because the piezoelectric actuator 22 is defective. Alternatively, the process is sent to a process for disassembling and recycling the inkjet head 3 (S202), and the flow ends.

  On the other hand, if the resonance frequencies of all the inspection units 22b are within the predetermined range R (S201: YES), the piezoelectric actuators 22 are further classified according to the resonance frequency of the inspection unit 22b (S203). Specifically, for example, the predetermined range R is divided into a plurality of ranges that do not overlap with each other, and the piezoelectric actuator 22 is changed depending on which of the plurality of ranges the average of the resonance frequencies Fe1 of the plurality of inspection units 22b falls within. Classify. The value of the driving potential applied to the individual electrode 45 and the driving waveform of the piezoelectric actuator 22 are set to a potential and waveform set in advance according to this classification. Then, after S203, the process proceeds to S104.

  In S <b> 104, bumps 48 are formed on the upper surface of the inspection electrode 46. Subsequently, the wiring 51 of the wiring member 50 is connected to the bump 48 (S105). Thereafter, the process proceeds to a subsequent manufacturing process for manufacturing the printer 1 such as assembling the inkjet head 3 connected with the FPC 50 to the carriage 2 manufactured in parallel with the inkjet head 3 (S106), and the printer 1 is completed. To end the flow.

  According to the embodiment described above, the resonance frequency of the inspection unit 22b can be detected by bringing the probe 63 into contact with the individual electrode 45 and applying a voltage to the inspection electrode 46 that is electrically connected to the individual electrode 45. it can. Then, based on the detected resonance frequency, it can be determined whether or not the piezoelectric actuator 22 has a predetermined performance.

  At this time, since the individual electrode 45 is used as a pad for contacting the probe 63, it is not necessary to provide a dedicated pad separately, and an increase in size of the piezoelectric actuator 22 can be suppressed.

  In particular, in the present embodiment, the piezoelectric actuator 22 has a plurality of drive units 22a, and an inspection unit 22b is provided for each of the plurality of drive units 22a. Therefore, unlike this embodiment, when a dedicated pad is provided separately from the individual electrode 45, a plurality of pads are provided, and the enlargement of the piezoelectric actuator 22 becomes remarkable. On the other hand, in this Embodiment, the enlargement of the piezoelectric actuator 22 can be suppressed especially effectively by using the individual electrode 45 as a pad.

  In the present embodiment, the individual electrode 45 and the inspection electrode 46 are electrically connected, and the individual electrode 45 is used as a pad for contacting the probe 63. Is applied to the individual electrode 45 at the same frequency.

  However, in the present embodiment, the resonance frequency of the drive unit 22a and the resonance frequency of the inspection unit 22b are different because the size of the pressure chamber 10 and the size of the inspection space 17 are different in plan view. ing. Specifically, the resonance frequency Fe1 in the primary vibration mode of the inspection unit 22b is a substantially intermediate frequency between the resonance frequency Fd1 in the primary vibration mode of the drive unit 22a and the resonance frequency Fd2 in the secondary vibration mode. .

  When detecting the resonance frequency of the inspection unit 22b, the resonance frequency Fe1 in the primary vibration mode of the inspection unit 22b and the resonance frequencies Fd1 and Fd2 in the primary vibration mode and the secondary vibration mode of the drive unit 22a are included. The frequency of the voltage applied from the probe 63 to the individual electrode 45 and the inspection electrode 46 is changed within a range that does not include.

  Therefore, when detecting the resonance frequency of the inspection unit 22b, the frequency of the voltage applied to the individual electrode 45 does not become the resonance frequency of the drive unit 22a. That is, the drive unit 22a does not resonate. Therefore, it is possible to prevent the ceramic layer 42 and the piezoelectric layer 43 from forming a drive portion 22a from being cracked, and the drive portion 22a from being unable to be driven normally. In addition, about the part which forms the test | inspection part 22b of the ceramic layer 42 and the piezoelectric layer 43, even if it cracks when the test | inspection part 22b is resonated, it will interfere with the drive of the subsequent drive part 22a. Never come.

  In the present embodiment, the current value Ie peak output from the common electrode 44 is sharp even when the planar shape of the inspection space 17 is circular. Further, in the present embodiment, the planar shape of the inspection space 17 and the planar shape of the inspection electrode 46 are both circular, and the peak of the current value Ie becomes sharp even when they have a similar relationship. In the present embodiment, since the inspection electrode 46 is smaller than the inspection space 17 in plan view, the deformation amount of the inspection portion 22b when a voltage is applied to the inspection electrode 46 increases. And in this Embodiment, it is easy to detect a resonant frequency from these things.

  In the present embodiment, after the resonance frequency of the inspection portion 22b is formed, bumps 48 are formed on the upper surface of the inspection electrode 46, thereby connecting the inspection electrode 46 to the wiring 51 of the FPC 50. Used as a connection terminal. Therefore, it is possible to suppress an increase in size of the piezoelectric actuator 22 as compared with the case where a separate connection terminal is formed on the upper surface of the piezoelectric layer 43.

  In particular, in the present embodiment, since the piezoelectric actuator 22 has a plurality of drive units 22a, it is necessary to provide connection terminals individually for the individual electrodes 45 of the plurality of drive units 22a. Therefore, unlike the present embodiment, when the connection terminal is provided separately from the inspection electrode 46, the piezoelectric actuator 22 is significantly increased in size. On the other hand, in the present embodiment, the use of the inspection electrode 46 as a connection terminal can particularly effectively suppress an increase in size of the piezoelectric actuator 22.

  In the present embodiment, a plurality of pressure chambers 10, that is, a plurality of driving units 22 a are arranged in the paper feeding direction, whereas the inspection space 17 is in the paper feeding direction of each pressure chamber 10. Therefore, even when the inspection space 17 and the inspection portion 22b are provided, the arrangement intervals of the plurality of pressure chambers 10 and the drive portions 22a do not increase.

  In the present embodiment, the inkjet head 3 corresponds to the liquid ejection apparatus according to the present invention. The combination of the ink separation layer 41 and the ceramic layer 42 corresponds to the first layer according to the present invention, and the piezoelectric layer 43 corresponds to the second layer according to the present invention. Further, the upper surface of the piezoelectric layer 43 corresponds to the surface of the second layer according to the present invention on the side opposite to the first layer. The individual electrode 45 corresponds to the driving electrode according to the present invention.

  Further, the paper feeding direction in which the plurality of pressure chambers 10 are arranged corresponds to one direction according to the present invention. Further, the vertical direction in which the flow path unit 21 and the piezoelectric actuator 22 are stacked corresponds to the stacking direction according to the present invention. The step S102 corresponds to the resonance frequency detection step according to the present invention. The step S103 corresponds to the determination step according to the present invention. The step S104 corresponds to a bump forming step according to the present invention.

  Next, modified examples in which various changes are made to the present embodiment will be described. However, description of components having the same configuration as in this embodiment will be omitted as appropriate.

  In the above-described embodiment, the planar shape of the inspection space 17 is substantially circular, and the planar shape of the inspection electrode 46 is substantially circular smaller than the inspection space 17, but is not limited thereto.

  For example, the planar shape of the inspection space 17 and the inspection electrode 46 may be a shape other than a circle such as a substantially rectangular shape. In addition, the planar shape of the inspection space 17 and the planar shape of the inspection electrode 46 are such that the planar shape of the inspection space 17 is substantially rectangular while the planar shape of the inspection electrode 46 is substantially circular. It does not have to be similar. Further, the inspection electrode 46 may be larger than the inspection space 17 and may protrude from the inspection space 17 in plan view.

  Further, in the above-described embodiment, when detecting the resonance frequency of the inspection unit 22b, the detection frequency is within a range that includes the resonance frequency of the inspection unit 22b and is not estimated to include the resonance frequency of the drive unit 22a. Although the frequency of the voltage applied to the electrode 46 was changed, it is not restricted to this. When detecting the resonance frequency of the inspection unit 22b, the voltage applied to the inspection electrode 46 may be changed in a range including both the resonance frequency of the drive unit 22a and the resonance frequency of the inspection unit 22b.

  In the above-described embodiment, the resonance frequency Fe1 in the primary vibration mode of the inspection unit 22b is an intermediate frequency between the resonance frequency Fd1 in the primary vibration mode of the drive unit 22a and the resonance frequency Fd2 in the secondary vibration mode. The resonance frequency Fe1 in the primary vibration mode is detected as the resonance frequency of the inspection unit 22b, but is not limited thereto.

  For example, the two other adjacent vibration modes of the drive unit 22a such that the resonance frequency in the primary vibration mode of the inspection unit 22b is between the resonance frequency in the secondary vibration mode and the resonance frequency in the tertiary vibration mode of the drive unit 22a. It may be a frequency between the resonance frequencies. Further, the resonance frequency in the vibration mode other than the primary vibration mode of the inspection unit 22b is a frequency between the resonance frequencies in the two adjacent vibration modes of the drive unit 22a, and the resonance frequency of the inspection unit 22b is You may detect the resonant frequency in another vibration mode.

  Furthermore, the resonance frequency of the drive unit 22a is not limited to the resonance frequency of the inspection unit 22b, and the resonance frequency of the drive unit 22a and the resonance frequency of the inspection unit 22b may be the same. .

  In the above-described embodiment, the plurality of pressure chambers 10 and the plurality of driving units 22a are arranged in the paper feeding direction, whereas the inspection space 17 and the inspection unit 22b are in the scanning direction of the pressure chambers 10. However, the present invention is not limited to this. For example, the inspection space 17 and the inspection unit 22b may be disposed at other positions such as between the adjacent pressure chambers 10 and the drive unit 22a in plan view.

  In the above-described embodiment, the inspection units 22b are individually provided for the plurality of drive units 22a. However, the present invention is not limited to this. For example, one inspection unit 22b is provided for the drive unit 22a corresponding to one pressure chamber row 9, or one inspection unit 22b is provided for all the drive units 22a. One inspection unit 22b may be provided for the plurality of drive units 22a.

  Further, in the above-described embodiment, the inspection electrode 46 is formed on the upper surface of the piezoelectric layer 43 like the individual electrode 45, and the individual electrode 45 and the inspection electrode 46 are connected to each other on the upper surface of the piezoelectric layer 43. However, the present invention is not limited to this. For example, the inspection electrode 46 is provided in a portion overlapping the inspection space 17 between the ceramic layer 42 and the piezoelectric layer 43, and the individual electrode 45 and the corresponding inspection electrode 46 are formed in the piezoelectric layer 43. Conduction may be made through a formed through hole. In this case, in addition to the common electrode 44, an electrode is provided in a portion overlapping the inspection space 17 on the upper surface of the piezoelectric layer 43, and a current output from the electrode is detected by the current detection device 61. And what is necessary is just to detect the resonant frequency of the test | inspection part 22b.

  In the above-described embodiment, the ceramic layer 42 and the piezoelectric layer 43 are continuously extended across all the pressure chambers 10 and all the test spaces 17, but are not limited thereto. For example, in one modification, as shown in FIGS. 8 and 9, a plurality of pairs of pressure chambers 10 and test spaces 17 extending on the upper surface of the ink separation layer 41 are extended over only one set. A ceramic layer 42 and a piezoelectric layer 43 are provided.

  Further, the common electrode 44 is led out to a surface electrode 72 formed on the upper surface of the ink separation layer 41 via a conductive adhesive 71 formed on the side surface of the piezoelectric actuator 22. The surface electrode 72 is connected to the wiring 51 of the FPC 50 through the bump 73.

  Further, in the above modification, the ceramic layer 42 and the piezoelectric layer 43 extend over only the pair of the pressure chamber 10 and the inspection space 17, but the present invention is not limited to this. The ceramic layer 42 and the piezoelectric layer 43 may extend across a plurality of sets of pressure chambers 10 and inspection spaces 17, such as a pair of two pressure chambers 10 and an inspection space 17.

  In the above description, the present invention is applied to an inkjet head that ejects ink from nozzles. However, the present invention is not limited to this. The present invention can also be applied to a liquid ejection device other than an inkjet head that ejects liquid other than ink from a nozzle, or a performance inspection method of a piezoelectric actuator used in the liquid ejection device.

DESCRIPTION OF SYMBOLS 3 Inkjet head 10 Pressure chamber 15 Nozzle 17 Inspection space 21 Flow path unit 22 Piezoelectric actuator 22a Drive part 22b Inspection part 41 Ink separation layer 42 Ceramic layer 43 Piezoelectric layer 45 Individual electrode 46 Inspection electrode 47 Conductive part 48 Bump 50 FPC

Claims (15)

A nozzle,
A pressure chamber communicating with the nozzle;
A flow path unit having an inspection space provided separately from the pressure chamber;
A first layer covering the pressure chamber and the inspection space;
A second layer made of a piezoelectric material, disposed on the surface of the first layer opposite to the pressure chamber, and continuously extending across the pressure chamber and the inspection space;
A driving electrode formed in a portion overlapping the pressure chamber on the surface of the second layer opposite to the first layer;
A liquid ejecting apparatus comprising: a piezoelectric actuator formed on a portion of the piezoelectric layer that overlaps the inspection space and having an inspection electrode electrically connected to the driving electrode.   A drive that is a portion overlapping the pressure chamber of the piezoelectric actuator because the size of the pressure chamber and the size of the inspection space are different from each other when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. 2. The liquid ejection apparatus according to claim 1, wherein a resonance frequency of the inspection portion is different from a resonance frequency of the inspection portion which is a portion overlapping the inspection space of the piezoelectric actuator.   3. The liquid ejection apparatus according to claim 1, wherein the inspection space is circular as viewed from a stacking direction of the flow path unit and the piezoelectric actuator.   The shape of the space for inspection and the shape of the electrode for inspection are similar when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. The liquid discharge apparatus according to 1.   The liquid ejection apparatus according to claim 1, wherein the inspection electrode is smaller than the inspection space when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. A plurality of the pressure chambers are arranged along one direction;
The liquid ejection apparatus according to claim 1, wherein the inspection space is provided at a position adjacent to the pressure chamber with respect to a direction orthogonal to the one direction. A flow path unit having a nozzle and a pressure chamber communicating with the nozzle;
A piezoelectric actuator for inspecting the liquid in the pressure chamber, and a piezoelectric actuator performance inspection method in a liquid ejection device comprising:
The channel unit is
An inspection space provided separately from the pressure chamber,
The piezoelectric actuator is
A first layer covering the pressure chamber and the inspection space;
A second layer made of a piezoelectric material, disposed on the surface of the first layer opposite to the pressure chamber, and continuously extending across the pressure chamber and the inspection space;
A driving electrode formed in a portion overlapping the pressure chamber on the surface of the second layer opposite to the first layer;
An inspection electrode formed on a portion of the second layer that overlaps the inspection space and electrically connected to the driving electrode;
Resonance frequency detection step of detecting a resonance frequency of an inspection portion that is a portion overlapping with the inspection space of the piezoelectric actuator by applying a voltage to the inspection electrode and changing the frequency of the voltage;
A determination step of determining whether or not a drive unit that is a portion overlapping the pressure chamber of the piezoelectric actuator has a predetermined performance from the resonance frequency detected in the resonance frequency detection step,
In the resonance frequency detecting step, a voltage is applied to the inspection electrode by bringing a probe for applying a voltage to the inspection electrode into contact with the drive electrode.   The resonance frequency of the driving unit and the resonance frequency of the inspection unit are different from each other in that the size of the pressure chamber and the size of the inspection space are different when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. The method for inspecting the performance of a piezoelectric actuator according to claim 7, wherein:   9. The resonance frequency detecting step, wherein a frequency of a voltage applied to the inspection electrode is changed in a range including a resonance frequency of the inspection unit and not including a resonance frequency of the driving unit. 4. A method for inspecting performance of the piezoelectric actuator according to 1. The inspection electrode is formed on a surface of the second layer opposite to the first layer;
After the resonance frequency detecting step, the method further comprises a bump forming step of forming a bump for connecting to the wiring member on the surface of the inspection electrode opposite to the first layer. A method for inspecting performance of a piezoelectric actuator according to any one of claims 7 to 9.   The method for inspecting the performance of a piezoelectric actuator according to any one of claims 7 to 10, wherein the inspection space is circular when viewed from the stacking direction of the flow path unit and the piezoelectric actuator.   The shape of the inspection space and the shape of the inspection electrode are similar when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. 4. A method for inspecting performance of the piezoelectric actuator according to 1.   The method for inspecting a piezoelectric actuator according to any one of claims 7 to 12, wherein the inspection electrode is smaller than the inspection space when viewed from the stacking direction of the flow path unit and the piezoelectric actuator. . The resonance frequency in the primary vibration mode of the inspection unit is a frequency between the resonance frequency in the primary vibration mode of the drive unit and the resonance frequency in the secondary vibration mode,
The piezoelectric actuator performance inspection method according to claim 8 or 9, wherein, in the resonance frequency detection step, a resonance frequency in a primary vibration mode of the inspection unit is detected. The flow path unit includes a plurality of the pressure chambers,
The piezoelectric actuator includes a plurality of driving electrodes corresponding to the plurality of pressure chambers;
A plurality of the pressure chambers are arranged along one direction;
15. The inspection space is provided at a position adjacent to at least one of the plurality of pressure chambers with respect to a direction orthogonal to the one direction. Piezoelectric actuator performance inspection method.

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