JP4692662B2 - Method for manufacturing liquid ejection device - Google Patents

Description

  The present invention relates to a method for manufacturing a liquid discharge apparatus, in which a liquid discharge apparatus is manufactured by joining a flow path unit and an actuator unit.

  As a liquid ejection device manufactured by joining a flow path unit and an actuator unit, for example, an ink ejection device is well known, and an example thereof is disclosed in Patent Document 1. An ink ejection device disclosed in Patent Document 1 includes a flow path unit having a plurality of nozzles that eject ink and a plurality of pressure chambers individually connected to the plurality of nozzles, and ink in the plurality of pressure chambers. And an actuator unit having a plurality of drive units for selectively applying the discharge pressure. The flow path unit is manufactured by stacking a plurality of plates, and a plurality of nozzles and a plurality of pressure chambers are formed in the flow path unit by communicating holes or recesses formed in each plate. Etc. are formed. On the other hand, the actuator unit is manufactured by laminating a plurality of ceramic sheets having a conductive material printed on the surface and then firing the laminated body. By the conductive material printed on the surface of the ceramic sheet, A constant potential electrode and an individual electrode are configured. Also, the active part is configured by polarization processing a part of the ceramic sheet sandwiched between the constant potential electrode and the individual electrode, and the active part is driven by the driving voltage applied between the constant potential electrode and the individual electrode. Is driven to apply a discharge pressure to the ink in the pressure chamber. That is, the drive unit is configured by the constant potential electrode, the individual electrode, and the active unit. When manufacturing the ink ejection device, the flow path unit and the actuator unit are manufactured, and then they are joined to each other.

JP 2004-304027 A JP 2004-48985 A

  In the ink ejection device of Patent Document 1, since the flow path unit and the actuator unit are manufactured separately and then joined together, dimensional errors are likely to occur in the respective manufacturing processes of the flow path unit and the actuator unit. There is a problem in that the dimensional accuracy of the ink ejection device varies. In particular, in the actuator unit, the pitch of the plurality of electrodes (that is, the distance between the electrodes) is likely to vary due to the shrinkage at the time of firing, and the position of the active part may be deviated from the design appropriate position. If the position of the active part is shifted, the position of the active part with respect to the pressure chamber is shifted when the flow path unit and the actuator unit are joined, so that an appropriate discharge pressure is applied to the ink in the pressure chamber. There is a problem that the discharge characteristics (discharge speed and the like) deteriorate.

  As means for solving such a problem, Patent Document 2 discloses variations in ejection characteristics in a plurality of drive units by inspecting the characteristics of a plurality of drive units and controlling the drive voltage based on the inspection results. Techniques for mitigating are disclosed. However, this technique has a problem that the configuration for inspecting the characteristics of a plurality of drive units becomes complicated, resulting in an increase in manufacturing cost. In particular, when the drive unit has a plurality of active parts, it is necessary to inspect the characteristics of each of the plurality of active parts, and thus there is a problem that the configuration is further complicated and the manufacturing cost is further increased.

  The present invention has been made to solve the above-described problems, and can prevent deterioration of discharge characteristics due to variations in pitch of a plurality of electrodes corresponding to a plurality of pressure chambers with a simple configuration. An object of the present invention is to provide a method for manufacturing a liquid ejection device.

  In order to solve the above-described problems, a method of manufacturing a liquid ejection device according to the present invention includes a plurality of nozzles that eject liquid and the plurality of nozzles individually communicated with each other at regular intervals along one direction. A plurality of pressure chambers arranged in a flow path unit provided with openings of each of the plurality of pressure chambers on one surface, a diaphragm for closing each of the openings of the plurality of pressure chambers, A plurality of drive units that selectively apply discharge pressure to the liquid in the plurality of pressure chambers by driving the diaphragm, and an actuator unit joined to the one surface of the flow path unit, Each of the plurality of driving units corresponds to an individual electrode positioned corresponding to the pressure chamber when viewed from the one surface side, and a central region of the individual electrode in the one direction when viewed from the one surface side. Then And a first constant potential electrode positioned corresponding to the total length of the individual electrode in a direction orthogonal to the one direction, and at least outside the central region of the individual electrode when viewed from the one surface side. A second constant potential electrode positioned corresponding to the outer region, a first active portion positioned between the individual electrode and the first constant potential electrode, and the individual electrode and the second constant potential electrode. A method of manufacturing a liquid ejection device having a second active part positioned between the manufacturing method, (a) a step of manufacturing the flow path unit and the actuator unit, and (b) the plurality Measuring the pitch in the one direction with respect to the first constant potential electrode, and measuring the pitch in the one direction with respect to the plurality of pressure chambers; and (c) the plurality of second measured in the step (b). A step of selecting a combination of the actuator unit and the flow path unit in which the pitch of the constant potential electrode and the pitch of the plurality of pressure chambers are within a predetermined allowable error; and (d) selected in the step (c) Joining the actuator unit and the flow path unit in combination.

  In the drive unit of the actuator unit, the first constant potential electrode is positioned corresponding to the central region of the individual electrode in one direction, and is positioned corresponding to the total length of the individual electrode in a direction orthogonal to the one direction. . And the part corresponding to the center area | region in a diaphragm is driven by the drive voltage applied to the 1st active part located between an individual electrode and a 1st constant potential electrode, and thereby discharge pressure is applied to the liquid in a pressure chamber. Is granted. Therefore, in order to homogenize the liquid ejection characteristics of the plurality of driving units, in each of the plurality of driving units, the facing portion where the individual electrode and the first constant potential electrode are opposed is positioned in the central region of the pressure chamber. Need to be.

  Here, since the first constant potential electrode is positioned corresponding to the total length of the individual electrode in the direction orthogonal to the one direction, the position of the first constant potential electrode is orthogonal when the actuator unit is manufactured. Even if it is displaced in the direction, the position of the facing portion does not vary greatly. In addition, since the first constant potential electrode is positioned corresponding to the central region of the individual electrode in the one direction, even if the position of the individual electrode is shifted in the one direction, the position of the facing portion varies greatly. Never do. However, when the position of the first constant potential electrode is shifted in the one direction, the position of the facing portion varies greatly. That is, the “positional displacement of the first constant potential electrode in the one direction” has a great influence on the positioning of the facing portion when manufacturing the actuator unit.

  In this configuration, the pitch of the plurality of first constant potential electrodes in the one direction and the pitch of the plurality of pressure chambers in the one direction are measured, and the actuator unit and the flow path unit are within a predetermined tolerance. Therefore, it is possible to preferentially solve the problem of “positional displacement of the facing portion relative to the pressure chamber” caused by “positional displacement of the first constant potential electrode in the one direction”. The opposing portion is positioned in the central region of the pressure chamber in the one direction without special consideration of misalignment in other elements (individual electrodes, etc.) and other directions (directions orthogonal to one direction). be able to.

  The present invention has been made to solve the above-described problems, and prevents deterioration of discharge characteristics due to variation in pitch of a plurality of electrodes formed corresponding to each of a plurality of pressure chambers with a simple configuration. can do.

It is a perspective view which shows the structure of the liquid discharge apparatus which concerns on embodiment. It is a top view which shows the structure which joined the flow-path unit and the actuator unit. It is a fragmentary sectional view of the Y direction which shows the structure which joined the flow path unit and the actuator unit. It is a fragmentary sectional view of the X direction which shows the structure which joined the flow path unit and the actuator unit. It is a figure which shows the structure of each electrode of an actuator unit, (A) is the partial expanded plan view which shows the structure of a 2nd constant potential electrode, (B) is the partial enlarged plan view which shows the structure of a 1st constant potential electrode, C) is a partially enlarged plan view showing a configuration of an individual electrode. It is a partial enlarged plan view which shows the positional relationship of each electrode of an actuator unit. It is a figure which shows the state which the position of the individual electrode shifted | deviated from the appropriate position, (A) is the elements on larger scale which show the state which the individual electrode shifted | deviated to the Y direction, (B) is the state which the individual electrode shifted | deviated to the X direction. FIG. It is a figure which shows the state which the position of the 1st constant potential electrode shifted | deviated from the appropriate position, (A) is a partial enlarged plan view which shows the state which the 1st constant potential electrode shifted | deviated to the Y direction, (B) is a 1st fixed potential. It is a partial enlarged plan view which shows the state which the electric potential electrode shifted | deviated to the X direction. It is a graph which shows the relationship between the deviation | shift amount of an electrode, and the ratio of the displacement volume in a pressure chamber, (A) is a graph which shows the relationship between the X direction deviation | shift amount of an individual electrode, and the ratio of displacement volume, (B) is 1st. It is a graph which shows the relationship between the X direction deviation | shift amount of a constant potential electrode, and the ratio of displacement volume.

Hereinafter, a “method for manufacturing a liquid ejection device” according to a preferred embodiment of the present invention will be described with reference to the drawings. In the following embodiments, the present invention is applied to an “ink discharge device”. However, the present invention can be applied to a “colored liquid discharge device” that discharges a colored liquid or a “conductive liquid discharge device that discharges a conductive liquid. It is also applicable to other “liquid ejecting apparatuses” such as “ When the present invention is applied to a “colored liquid ejecting apparatus” or “conductive liquid ejecting apparatus”, “ink” used in the following description is read as “colored liquid” or “conductive liquid”. Further, “lower” used in the following description means the direction in which ink is ejected, and “upper” means the opposite direction.
[Overall configuration of ink ejection device]
FIG. 1 is an exploded perspective view showing the configuration of the ink ejection device 10. The ink ejection apparatus 10 uses a plurality of nozzles 14 (FIG. 3) based on the drive voltage generated by the driver IC 12 for ink of four colors, black (BK), yellow (Y), cyan (C), and magenta (M). ) To a discharge object (paper or the like) selectively, and has a flow path unit 16, an actuator unit 18, and a wiring board 20, as shown in FIG.

Although not shown, the ink ejection device 10 is configured to eject ink from the nozzles 14 (FIG. 3) toward the ejection target that is transported by the transport device while being mounted on a carriage and reciprocally moved. The movement direction of the ink discharge device 10 and the conveyance direction of the discharge target are orthogonal to each other. Therefore, in the following description, the conveyance direction of the ejection target is referred to as “conveyance direction X”, and the movement direction of the ink ejection apparatus 10 (that is, the scanning direction of the nozzle 14) is referred to as “scanning direction Y”.
<Flow path unit>
As shown in FIG. 3, the flow path unit 16 is configured by stacking five plates 22 a to 22 e, and “concave portions” or “through holes” formed in these plates 22 a to 22 e are mutually connected. By communicating, four ink flow paths N1 to N4 (FIG. 1) are configured for each ink color. That is, the flow path unit 16 includes a manifold 24 for storing ink, an ink supply port 26 (FIG. 1) for supplying ink to the manifold 24, a plurality of nozzles 14 for discharging ink in the manifold 24 to the outside, and a manifold. A plurality of individual flow paths 28 that communicate the 24 and the plurality of nozzles 14 are configured for each color of ink. Each of the plurality of individual flow paths 28 is formed with a pressure chamber 30 that communicates with the nozzle 14 individually. One surface of the flow path unit 16 (in this embodiment) is formed above the pressure chamber 30. An opening 30a is formed in the upper surface 16a.

  As shown in FIG. 5A, the plurality of pressure chambers 30 form a pressure chamber row L by being arranged at regular intervals along the transport direction X (that is, “one direction”), A plurality of pressure chamber rows L are arranged in parallel to each other at intervals in the scanning direction Y. In each of the ink flow paths N1 to N4 (FIG. 1), two pressure chamber rows L that are close to each other form a pair, and in the pair of pressure chamber rows L, a plurality of nozzles in one pressure chamber row L. 14 and the plurality of nozzles 14 of the other pressure chamber example L are arranged in a zigzag manner at the center in the scanning direction Y. The shape of each of the plurality of pressure chambers 30 in plan view (that is, the shape when viewed from above) is designed to be a substantially rectangular shape having a long side extending in the scanning direction Y. The pitch P1 is designed to be constant over the entire length of the pressure chamber row L. In the flow path unit 16, since a dimensional error occurs in the process of stacking the five plates 22a to 22e, the actually measured pitch P1 does not necessarily match the design appropriate pitch.

The actuator unit 18 is joined to the one surface 16 a of the flow path unit 16, whereby the respective openings 30 a of the plurality of pressure chambers 30 are closed.
<Actuator unit>
As shown in FIGS. 2, 3, and 4, the actuator unit 18 applies ejection pressure to the ink existing in the pressure chamber 30, and drives the diaphragm 32 and the diaphragm 32 by driving the diaphragm 32. And a plurality of drive units 34 that selectively apply ejection pressure to the ink in the plurality of pressure chambers 30.

  The diaphragm 32 closes the respective openings 30a of the plurality of pressure chambers 30 and causes the pressure chambers 30 to change in volume by being deformed by the drive unit 34. Lead zirconate titanate (PZT) It is formed of a piezoelectric material having as a main component. However, the material of the diaphragm 32 is not limited to the piezoelectric material.

  Each of the plurality of driving units 34 is integrally formed on the upper surface of the diaphragm 32. As shown in FIGS. 3 and 4, the lower piezoelectric layer 36, the upper piezoelectric layer 38, and the second constant potential are provided. The electrode 40 includes a first constant potential electrode 42, a plurality of individual electrodes 44, a first active part 46, and a second active part 48. The lower piezoelectric layer 36 constitutes a second active portion 48 described later, and the upper piezoelectric layer 38 constitutes a first active portion 46 and a second active portion 48 described later, which are titanic acid. It is made of a piezoelectric material mainly composed of lead zirconate (PZT). Each of the second constant potential electrode 40, the first constant potential electrode 42, and the plurality of individual electrodes 44 generates an electric field for driving the first active portion 46 and the second active portion 48 in a predetermined manner. , Ag—Pd and the like.

  As shown in FIG. 4, the second constant potential electrode 40 is positioned opposite to each of the plurality of individual electrodes 44, thereby forming a second active portion configured in each of the lower piezoelectric layer 36 and the upper piezoelectric layer 38. As shown in FIG. 5 (A), the electric field is applied to 48 and is sufficiently larger than the width of the pair of pressure chamber rows L so as to correspond to the entire pair of pressure chamber rows L in the flow path unit 16. It is formed in a strip shape having a wide width and extending in the transport direction X. Although not shown, the second constant potential electrode 40 is a second surface terminal formed on the upper surface of the actuator unit 18 through a conductive portion formed through the lower piezoelectric layer 36 and the upper piezoelectric layer 38. Is electrically connected.

  As shown in FIG. 4, the first constant potential electrode 42 is located opposite to each of the plurality of individual electrodes 44, thereby applying an electric field to the first active portion 46 formed in the upper piezoelectric layer 38. It is formed so as to partially correspond to each of the plurality of pressure chambers 30 in the flow path unit 16. As shown in FIG. 5B, the first constant potential electrode 42 includes a plurality of electrode portions 42a having a long side extending in the scanning direction Y and a substantially rectangular shape in plan view, and a plurality of electrode portions 42a in a pair of pressure chamber rows. And a strip-shaped connection portion 42b that is electrically connected on both sides in the width direction of L (that is, the scanning direction Y). Each of the plurality of electrode portions 42a corresponds to the central region of the pressure chamber 30 and is disposed so as to correspond to the entire length of the pressure chamber 30 in the scanning direction Y. A region that does not face 42a is secured outside the central region. Although not shown, the connection portion 42b of the first constant potential electrode 42 is connected to the first surface terminal formed on the upper surface of the actuator unit 18 through the conductive portion formed through the upper piezoelectric layer 38. Electrically connected.

  As shown in FIG. 4, each of the plurality of individual electrodes 44 is positioned opposite to each of the second constant potential electrode 40 and the first constant potential electrode 42, thereby forming the first piezoelectric layer 38. An electric field is selectively applied to the active portion 46 and the second active portion 48 continuously formed in each of the upper piezoelectric layer 38 and the lower piezoelectric layer 36, as shown in FIG. Each of the plurality of pressure chambers 30 is formed to individually correspond to each other. The individual electrode 44 includes a substantially rectangular electrode portion 44a having a long side extending in the scanning direction Y, and a width direction in the pair of pressure chambers L (that is, the end of the electrode portion 44a opposite to the nozzle 14 side) And a terminal portion 44b formed to extend outward in the scanning direction Y). The length in the scanning direction Y of the electrode portion 44 a is designed to be substantially the same as the length of the scanning direction Y in the pressure chamber 30, and the length in the transport direction X in the electrode portion 44 a is the same as that in the transport direction X in the pressure chamber 30. Designed to be slightly longer than the length. Therefore, the area when the pressure chamber 30 is viewed in plan and the area when the electrode portion 44a is viewed in plan are substantially the same.

  When each of the second constant potential electrode 40, the first constant potential electrode 42, and the plurality of individual electrodes 44 is viewed from the one surface 16a side of the flow path unit 16, it can be seen from the partially enlarged plan view shown in FIG. In addition, the individual electrodes 44 (portions indicated by oblique lines) are positioned corresponding to the pressure chambers 30 (portions indicated by two-dot chain lines), and the first constant potential electrodes 42 (portions indicated by broken lines) are arranged in the X direction. It is located corresponding to the central region (part drawn with a dashed line) S of the individual electrode, and is located corresponding to the entire length of the individual electrode 44 in the Y direction. Further, the second constant potential electrode 40 (portion drawn with a broken line) is positioned corresponding to the outer region G positioned outside the central region S of at least the individual electrode 44 in the transport direction X.

Then, as shown in FIG. 4, a part of the upper piezoelectric layer 38 located between the individual electrode 44 and the first constant potential electrode 42 is polarized upward from the first constant potential electrode 42 toward the individual electrode 44. The part is the first active part 46. Further, a portion of each of the lower piezoelectric layer 36 and the upper piezoelectric layer 38 located between the individual electrode 44 and the second constant potential electrode 40 excluding a portion facing the first constant potential electrode 42 is It is polarized downward from the individual electrode 44 toward the second constant potential electrode 40, and this portion is the second active portion 48. Further, a part of the lower piezoelectric layer 36 located between the first constant potential electrode 42 and the second constant potential electrode 40 is polarized downward from the first constant potential electrode 42 toward the second constant potential electrode 40. ing.
<Wiring board>
The wiring board 20 (FIG. 1) includes a sheet-like board body made of a flexible synthetic resin material such as polyimide resin, and a driver IC 12 (FIG. 1) mounted on one surface of the board body. A first constant potential wiring that electrically connects the first constant potential electrode 42 of the actuator unit 18 to a predetermined potential (for example, 20V), and a second constant potential electrode 40 of the actuator unit 18 is electrically connected to the ground potential (0V). The second constant potential wiring to be connected and the plurality of driving wirings for electrically connecting the plurality of individual electrodes 44 of the actuator unit 18 and the driving output terminal of the driver IC 12 are provided. Then, the driver IC 12 always holds the first constant potential electrode 42 at a predetermined potential (for example, 20 V), the second constant potential electrode 40 is always held at the ground potential (0 V), and a plurality of individual electrodes 44. Are switched between a ground potential (0 V) and a predetermined potential (for example, 20 V).
[Operation of ink ejection device]
In a standby state before executing the ink ejection operation, the potential of the first constant potential electrode 42 is held at a predetermined potential (for example, 20 V), and the second constant potential electrode 40 is held at the ground potential (0 V). Each of the individual electrodes 44 is held at the ground potential (0 V). In this state, since a potential difference is generated between the individual electrode 44 and the first constant potential electrode 42, an upward electric field that is the same as the polarization direction is generated in the first active portion 46, and the first active portion 46 is horizontal. Shrink in the direction. As a result, the upper piezoelectric layer 38, the lower piezoelectric layer 36, and the portion of the diaphragm 32 facing the pressure chamber 30 are deformed so as to be convex toward the pressure chamber 30 as a whole, and the diaphragm 32 is not deformed. In comparison, the volume of the pressure chamber 30 is reduced.

  When ink is ejected from the nozzle 14, the potential of the individual electrode 44 is once switched to a predetermined potential (for example, 20V) and then returned to the ground potential (0V). When the potential of the individual electrode 44 is switched to a predetermined potential (for example, 20 V), the individual electrode 44 becomes the same potential as the first constant potential electrode 42 and is at a higher potential than the second constant potential electrode 40. The first active part 46 that has been returned is restored. Further, since a potential difference is generated between the individual electrode 44 and the second constant potential electrode 40, a downward electric field that is the same as the polarization direction is generated in the second active portion 48, and the second active portion 48 is horizontally oriented. Shrink. As a result, the upper piezoelectric layer 38, the lower piezoelectric layer 36, and the diaphragm 32 are deformed so as to be convex on the opposite side of the pressure chamber 30 as a whole, and the volume of the pressure chamber 30 increases. Thereafter, when the potential of the individual electrode 44 is returned to the ground potential (0 V), the portions of the upper piezoelectric layer 38, the lower piezoelectric layer 36, and the diaphragm 32 that face the pressure chamber 30 become convex toward the pressure chamber 30 again. Thus, the volume of the pressure chamber 30 is reduced. As a result, a discharge pressure is applied to the ink existing in the pressure chamber 30, and the ink is discharged from the nozzle 14.

Further, in the operation of ejecting ink, when the potential of the individual electrode 44 is switched from the ground potential (0 V) to a predetermined potential (for example, 20 V), the first active portion 46 extends to the state before contraction, and the first Since the second active part 48 contracts, the extension of the first active part 46 is absorbed by the contraction of the second active part 48. On the other hand, when the potential of the individual electrode 44 is returned from a predetermined potential (for example, 20V) to the ground potential (0V), the first active portion 46 contracts and the second active portion 48 extends to a state before contraction. Therefore, the contraction of the first active part 46 is absorbed by the extension of the second active part 48. Accordingly, it is possible to prevent the deformation of the portions of the lower piezoelectric layer 36 and the upper piezoelectric layer 38 facing the pressure chamber 30 from adversely affecting the discharge operation in the other pressure chambers 30.
[Manufacturing method of ink ejection apparatus]
When manufacturing the ink ejection device, (a) a “unit manufacturing process” for manufacturing the flow path unit 16 and the actuator unit 18, and (b) the transport direction X (that is, the plurality of first constant potential electrodes 42). “Pitch measurement step” of measuring the pitch P2 (FIG. 5B) in “one direction” and measuring the pitch P1 (FIG. 5A) in the transport direction X for a plurality of pressure chambers 30; c) “Combination step” for selecting a combination of the actuator unit 18 and the flow path unit 16 in which the pitch P2 of the plurality of first constant potential electrodes 42 and the pitch P1 of the plurality of pressure chambers 30 are within a predetermined tolerance. (D) The “joining step” for joining the actuator unit 18 and the flow path unit 16 according to the selected combination is executed in this order.

<Unit manufacturing process>
In the “unit manufacturing process”, when the flow path unit 16 is manufactured, the five plates 22a to 22e (FIG. 3) are positioned and joined to each other. On the other hand, when the actuator unit 18 is manufactured, the second constant potential electrode 40, the first piezoelectric element 36, and the first constant potential electrode 40 are formed on the surface of the ceramic green sheet corresponding to each of the diaphragm 32, the lower piezoelectric layer 36, and the upper piezoelectric layer 38 (FIG. 3). A conductive paste corresponding to each of the constant potential electrode 42 and the plurality of individual electrodes 44 (FIG. 3) is printed, and then these ceramic green sheets are stacked and fired. In this “unit manufacturing process”, a dimensional error occurs when the members are joined. In particular, in the actuator unit 18, it is necessary to determine the positional relationship between a plurality of electrodes with high accuracy. The influence of the dimensional error on the characteristics (discharge speed, etc.) becomes large.

  In the “unit manufacturing process”, each of the flow path unit 16 and the actuator unit 18 may be manufactured one by one, or a plurality of them may be manufactured. Further, only one of these may be manufactured and a plurality of the other may be manufactured.

<Pitch measurement process>
In the “pitch measurement step”, “pitch P2 (FIG. 5B) in the transport direction X of the plurality of first constant potential electrodes 42”, which greatly affects the ink ejection characteristics, is measured and corresponds to the pitch P2. “Pitch P <b> 1 (FIG. 5A) in the transport direction X of the plurality of pressure chambers 30” is measured. Hereinafter, the reason why the “pitch P2 in the transport direction X of the plurality of first constant potential electrodes 42” greatly affects the ink ejection characteristics will be described in detail.

  In the drive unit 34 of the actuator unit 18, as shown in FIG. 6, the first constant potential electrode 42 is positioned corresponding to the central region S of the individual electrode 44 in the transport direction X (that is, “one direction”), In the scanning direction Y, it is located corresponding to the entire length of the individual electrode 44. And the part corresponding to the center area | region S (FIG. 6) in the diaphragm 32 with the drive voltage applied to the 1st active part 46 (FIG. 4) located between the separate electrode 44 and the 1st constant potential electrode 42 is. As a result, a discharge pressure is applied to the liquid in the pressure chamber 30. Therefore, in order to homogenize the ink ejection characteristics of the plurality of driving units 34, the individual electrode 44 and the first constant potential electrode 42 are opposed to each other in each of the plurality of driving units 34 (hereinafter referred to as “opposing portion”). R) (FIG. 6) needs to be accurately positioned in the central region of the pressure chamber 30, and when the facing portion R is greatly deviated from the central region of the pressure chamber 30, Since the “ratio of displacement volume” becomes small, the ejection characteristics deteriorate. Here, the “ratio of displacement volume” is the amount of displacement relative to the appropriate displacement volume when the displacement volume when the volume of the pressure chamber 30 is appropriately displaced in the discharge operation is defined as the appropriate displacement volume. If the displacement volume ratio (%) is small, it becomes impossible to apply a sufficient discharge pressure to the ink in the pressure chamber 30, so the discharge speed is lowered and the discharge characteristics are deteriorated. .

  Considering the factors that affect the position of the facing portion R in the driving unit 34 shown in FIG. 6, first, the second constant potential electrode 40 does not directly contribute to driving the first active unit 46. In addition, since it has a width that is sufficiently wider than the width of the pair of pressure chambers L and extends in the transport direction X (FIG. 5A), the positional deviation affects the ejection characteristics. There is no. Therefore, it is not necessary to consider the displacement of the second constant potential electrode 40 in positioning the facing portion R.

  The individual electrode 44 directly contributes to the driving of the first active portion 46. As described above, the length of the electrode portion 44a in the scanning direction Y is designed to be substantially the same as the length of the pressure chamber 30 in the scanning direction Y. Since the length in the transport direction X in the electrode portion 44a is designed to be slightly longer than the length in the transport direction X in the pressure chamber 30 (FIG. 5C), the individual electrodes 44 are arranged in the scanning direction Y. Even when the position is displaced (FIG. 7A) or when the position is displaced in the transport direction X (FIG. 7B), the position of the facing portion R does not change. Therefore, it is not necessary to consider the positional deviation of the individual electrode 44 in positioning the facing portion R. FIG. 9A is a graph showing a change in the “displacement volume ratio” when the individual electrode 44 is displaced in the transport direction X. From this graph as well, the displacement is the “displacement volume ratio”. It is clear that it does not affect. 7 and 8, each of the individual electrode 44 and the first constant potential electrode 42 is indicated by hatching, and the facing portion R is located at a portion where these hatching overlap in a lattice shape. Moreover, the two-dot chain line in FIG. 7 and FIG. 8 shows the position before position shift.

  The first constant potential electrode 42 directly contributes to the driving of the first active portion 46. As described above, each of the plurality of electrode portions 42a corresponds to the central region of the pressure chamber 30, and the scanning direction Y 8 is arranged so as to correspond to the entire length of the pressure chamber 30 (FIG. 5B), and when the first constant potential electrode 42 is displaced in the scanning direction Y, as shown in FIG. In addition, the position of the facing portion R does not vary. Therefore, it is not necessary to consider the displacement of the first constant potential electrode 42 in the scanning direction Y in positioning the facing portion R. However, since the electrode portion 42a of the first constant potential electrode 42 is disposed corresponding to only the central region of the pressure chamber 30 in the transport direction X (FIG. 5B), the first constant potential electrode 42 is transported. When the position is displaced in the direction X, as shown in FIG. 8B, the position of the facing portion R varies greatly, and when the variation width is large, the “displacement volume ratio” of the pressure chamber 30 is changed. It becomes smaller and the discharge characteristics deteriorate. FIG. 9B is a graph showing a change in the “displacement volume ratio” when the first constant potential electrode 42 is displaced in the transport direction X. From this graph as well, the displacement is “displacement volume”. It is clear that it has a great influence on the ratio.

  From the above, it can be seen that only the “positional displacement of the first constant potential electrode 42 in the transport direction X” needs to be considered in positioning the facing portion R. Therefore, in the “pitch measurement step”, the “pitch P2 in the transport direction X of the plurality of first constant potential electrodes 42” reflecting the displacement is measured, and the following “combination step” is performed based on the pitch P2. Like to do. When at least one of the flow path unit 16 and the actuator unit 18 is manufactured in the “unit manufacturing process” described above, the pitch P1 and the pitch P2 are measured for all of them.

<Combination process>
In the “combination step”, the pitch P2 between the first constant potential electrodes 42 and the pitch P1 between the pressure chambers 30 measured in the “pitch measurement step” are analyzed, and the actuator unit 18 and the flow within the predetermined allowable error are analyzed. A combination with the road unit 16 is selected. In the present embodiment, the “pitch P2 of the plurality of first constant potential electrodes 42” reflecting “the positional deviation of the first constant potential electrodes 42 in the transport direction X” that greatly affects the positional accuracy of the facing portion R is used as a reference. Thus, since the combination of the actuator unit 18 and the flow path unit 16 is selected, in the “combination process”, misalignment of other elements (individual electrodes 44, etc.) and other directions (scanning direction Y, etc.) There is no need to consider.

  When manufacturing a plurality of actuator units 18 in the “unit manufacturing process”, the actuator unit combined with the flow path unit 30 based on the pitch P2 between the first constant potential electrodes 42 measured in the “pitch measurement process”. 18 may be selected from a plurality of actuator units 18. Further, when a plurality of both the flow path unit 16 and the actuator unit 18 are manufactured in the “unit manufacturing process”, the pitch P1 and the pitch P2 are analyzed for all of them, and the “pitch value (ie, distance)” or “ They may be ranked based on the “degree of pitch variation” or the like, and a combination of the actuator unit 18 and the flow path unit 16 belonging to the same rank may be selected.

<Joint process>
In the “joining process”, the actuator unit 18 and the flow path unit 16 related to the combination selected in the “combination process” are opposed to each other, and light is transmitted through each of the actuator unit 18 and the flow path unit 16, thereby both of them. The position of a marker (such as a printed sign) provided on the actuator is confirmed, and the actuator unit 18 and the flow path unit 16 are brought into contact so that one marker and the other marker overlap each other. At this time, an adhesive is applied to at least one surface of the actuator unit 18 and the flow path unit 16, and both are bonded by the adhesive. Note that the specific methods of “positioning” and “joining” in the “joining step” are not limited to the present embodiment, and a conventionally existing method can be appropriately selected and used. In addition, as a method of joining the actuator unit 18 and the wiring board 20, a known method can be appropriately selected and used.

E ... Side region S ... Central region G ... Outer region L ... Pressure chamber row R ... Opposite portions P1, P2 ... Pitch X ... Transport direction Y ... Scanning direction 10 ... Ink ejection device (liquid ejection device)
12 ... Driver IC
14 ... Nozzle 16 ... Flow path unit 16a ... One side 18 ... Actuator unit 20 ... Wiring board 30 ... Pressure chamber 30a ... Opening 32 ... Diaphragm 34 ... Drive part 36 ... Lower piezoelectric layer 38 ... Upper piezoelectric layer 40 ... Second constant potential Electrode 42 ... First constant potential electrode 44 ... Individual electrode 46 ... First active part 48 ... Second active part

Claims (3)

A plurality of nozzles for discharging a liquid; and a plurality of pressure chambers individually communicated with each of the plurality of nozzles and arranged at regular intervals along one direction. A flow path unit provided with each of the openings,
A diaphragm that closes the openings of the plurality of pressure chambers, and a plurality of drive units that selectively apply a discharge pressure to the liquid in the plurality of pressure chambers by driving the diaphragm. An actuator unit joined to the one surface of the flow path unit,
Each of the plurality of driving units corresponds to an individual electrode positioned corresponding to the pressure chamber when viewed from the one surface side, and a central region of the individual electrode in the one direction when viewed from the one surface side. And a first constant potential electrode positioned corresponding to the entire length of the individual electrode in a direction orthogonal to the one direction, and at least the central region of the individual electrode when viewed from the one surface side. A second constant potential electrode positioned corresponding to an outer region positioned on the outside; a first active portion positioned between the individual electrode and the first constant potential electrode; the individual electrode and the second constant potential. A method of manufacturing a liquid ejection device having a second active part located between the electrodes,
(A) producing the flow path unit and the actuator unit respectively;
(B) measuring the pitch in the one direction for the plurality of first constant potential electrodes, and measuring the pitch in the one direction for the plurality of pressure chambers;
(C) A combination of the actuator unit and the flow path unit in which the pitch of the plurality of first constant potential electrodes and the pitch of the plurality of pressure chambers measured in the step (b) are within a predetermined tolerance. A process to select;
(D) A method for manufacturing a liquid ejection device, comprising: a step of joining the actuator unit and the flow path unit according to the combination selected in the step (c).   The pitch of the plurality of first constant potential electrodes in a direction orthogonal to the one direction and the pitch of the plurality of pressure chambers in a direction orthogonal to the one direction are not measured in the step (b), The method for manufacturing a liquid ejection device according to claim 1, which is not considered in the step (c). In the step (a), a plurality of the actuator units are manufactured,
In the step (b), for each of the plurality of actuator units, the pitch of the plurality of first constant potential electrodes in the one direction is measured,
In the step (c), the actuator unit to be combined with the flow path unit is selected from the plurality of actuator units based on the pitch of the plurality of first constant potential electrodes measured in the step (b). The manufacturing method of the liquid discharge apparatus of Claim 1 or 2.

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