JP2006069112A - Ink-jet recording head and ink-jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink-jet recording head by which large output displacement can be obtained by reducing the restriction of the displacement at a driving part caused by an electrode pad part of a piezo-element, and an ink-jet recording device provided with the ink-jet recording head. <P>SOLUTION: The driving part 144D of the piezo-element 144 is polarized from an electrode plate 120 toward a nozzle plate 116. The electrode pad part 144P is polarized in the direction orthogonal to the polarized direction of the driving part 144D. The electrode pad part 144P is sheared and deformed so as to be inclined toward the driving part 144D by the impression of a driving voltage. Consequently, restriction force for deformation of the driving part 144D by the electrode pad part 144P is reduced. The output displacement at the driving part 144D becomes larger. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head and an ink jet recording apparatus.

  There is an ink jet recording head in which energy is applied to ink in an ink chamber by bending deformation of a so-called piezo actuator to eject ink droplets from nozzles. A piezoelectric actuator of such an ink jet recording head has a configuration in which a diaphragm and a piezoelectric element are joined, and is arranged corresponding to an ink chamber, and a driving portion that is deformed by application of a driving voltage, and a partition wall of the ink chamber Are arranged (fixed) corresponding to the electrode pad portion for connection with the electrical wiring, and these are integrated.

  In the ink jet recording head having such a structure, the drive unit and the electrode pad unit are integrated, and both are polarized in the same state. In the case of this structure, when a driving voltage is applied, the driving portion is bent and deformed by the bimorph effect, and the electrode pad portion also tends to contract in the in-plane direction, so that the electrode pad portion and the driving portion are attracted by an internal force. Become. As a result, the electrode pad portion restrains the deformation of the drive portion, and the output displacement may be reduced.

  In order to solve this problem, for example, in the droplet ejecting apparatus described in Patent Document 1, the piezoelectric transducer is continuously arranged in the ink chamber and the ink chamber forming member (partition wall), and the ink chamber in the piezoelectric transducer is disposed in the ink chamber. The corresponding part (driving part) is provided with two regions polarized in different directions. When a voltage is applied, the second region is subjected to shear deformation into a parallelogram shape, and the first region is subjected to longitudinal effect deformation to promote deformation of the second region.

In such a configuration of the cited document 1, the deformation restraint exerted by the portion corresponding to the ink chamber forming member (electrode pad portion) on the portion corresponding to the ink chamber (driving portion) of the piezoelectric transducer during voltage application is reduced. Although it was possible, there was a drawback that the configuration and the polarization procedure were complicated.
JP 2002-359410 A

  In consideration of the above facts, the present invention includes an ink jet recording head that has a simple configuration and can easily reduce displacement restraint of the drive unit by the electrode pad portion of the piezo element to obtain a large output displacement, and the ink jet recording head. It is an object to obtain an inkjet recording apparatus.

  According to the first aspect of the present invention, a plurality of ink chambers filled with ink, a nozzle for communicating ink in the ink chamber as ink droplets in communication with the ink chamber, and an opening surface of the ink chamber are arranged. A diaphragm that expands or compresses the ink chamber by deformation, an electrode pad portion that is joined to the diaphragm and disposed at a position corresponding to the chamber partition wall, and the ink chamber. A piezoelectric element integrated with a driving unit arranged at a corresponding position, and an electrode that generates a driving voltage according to image information between the diaphragm and the diaphragm arranged to sandwich the piezoelectric element. A first polarization unit polarized in a direction in which it is deformed by application of the drive voltage. De portion, said there is a second polarized portion which is polarized in the direction of shear deformation by the application of the drive voltage, characterized in that.

  In this ink jet recording head, when a driving voltage is applied to the piezo element, the driving portion is bent and deformed by the bimorph effect. By this deformation, the ink chamber is expanded or compressed, and the ink in the ink chamber is ejected as ink droplets from the nozzle.

  The drive unit of the piezo element is a first polarization unit, and is polarized in a direction in which it is deformed by application of a drive voltage. However, the electrode pad unit is polarized in a direction in which it is sheared by application of a drive voltage. As a result, the electrode pad portion undergoes shear deformation when a drive voltage is applied, so that the force that restrains the deflection deformation of the drive portion can be easily reduced with a simple configuration, and the output displacement of the drive portion increases.

  According to a second aspect of the present invention, in the first aspect of the present invention, the first polarization unit is polarized in the same direction as the voltage application direction of the drive voltage, and the second polarization unit is coupled with the drive voltage. It is characterized by being polarized in a direction substantially orthogonal to the voltage application direction.

  Thereby, a 1st polarization part and a 2nd polarization part are realizable by simple structure. Here, “substantially orthogonal” means that the electrode pad portion (second polarization portion) may be shear-deformed toward the drive portion (first polarization portion) by application of a drive voltage, and the polarization directions thereof are formed. The angle is approximately 45 degrees or more and 135 degrees or less.

  In the invention according to claim 2, as a polarization direction of the second polarization part, for example, as in claim 3, the electrode pad part is shear-deformed toward the drive part by application of the drive voltage. Or a direction from the boundary line between the electrode pad portion and the drive portion toward the outer periphery of the electrode pad portion.

  According to a fifth aspect of the invention, in the first aspect of the invention according to any one of the first to fourth aspects, the electrode pad portion is polarized on at least one of the electrode plate or the diaphragm, and the second. A polarization electrode pair for applying a polarization voltage for forming a polarization part is formed.

  In other words, the piezoelectric element according to the first aspect of the present invention may be one that is previously polarized so that the driving portion becomes the first polarization portion or polarized so that the electrode pad portion becomes the second driving portion. However, as described in claim 2, when a polarizing electrode pair is formed on at least one of the electrode plate and the diaphragm, the electrode pad portion of the piezo element is polarized in a later step and the second A polarization part can be constituted. For the drive part of the unpolarized piezo element, for example, a polarization voltage in the same direction as the drive voltage (thickness direction of the piezo element) is applied between the electrode plate and the diaphragm, and polarized, A 1st polarization part can be comprised.

  As a polarization electrode pair according to a fifth aspect, for example, as described in the sixth aspect, one of the polarization electrode pairs is formed along a boundary line between the drive section and the electrode pad section. The other is shaped so as to be separated by a substantially constant distance.

  According to a seventh aspect of the present invention, a plurality of ink chambers filled with ink, a nozzle for communicating ink in the ink chamber as ink droplets in communication with the ink chamber, and an opening surface of the ink chamber are arranged. A movable wall of the ink chamber that expands or compresses the ink chamber by deformation, an electrode pad portion that is joined to the vibration plate and disposed at a position corresponding to the chamber partition, and the ink chamber. A piezoelectric element integrated with a driving unit arranged at a corresponding position, and an electrode that generates a driving voltage corresponding to image information between the diaphragm and the diaphragm arranged between the diaphragm A plate, and the drive unit is a polarization unit that is polarized in a direction in which it is deformed by application of the drive voltage, and the electrode pad But there is a non-polarized portion, and wherein the.

  In this ink jet recording head, when a driving voltage is applied to the piezo element, the driving portion is bent and deformed by the bimorph effect. By this deformation, the ink chamber is expanded or compressed, and the ink in the ink chamber is ejected as ink droplets from the nozzle.

  The drive part of the piezo element is a polarization part, and is polarized in a direction in which it is deformed by application of a drive voltage, but the electrode pad part is a non-polarization part. As a result, the internal force that the drive unit and the electrode pad unit attract each other can be made smaller than that of the conventional structure, and the force that restrains the bending deformation of the drive unit can be easily reduced with a simple configuration, and the output displacement of the drive unit increases. .

  According to an eighth aspect of the present invention, a plurality of ink chambers filled with ink, a nozzle that communicates with the ink chamber and ejects ink in the ink chamber as ink droplets, and an opening surface of the ink chamber are disposed. A movable wall of the ink chamber that expands or compresses the ink chamber by deformation, an electrode pad portion that is joined to the vibration plate and disposed at a position corresponding to the chamber partition, and the ink chamber. A piezoelectric element integrated with a driving unit arranged at a corresponding position, and an electrode that generates a driving voltage corresponding to image information between the diaphragm and the diaphragm arranged between the diaphragm A plate, and the drive unit is polarized in a direction in which it is deformed by application of the voltage, and at least of the diaphragm and the electrode plate Write to the the electrode pad portion non-application portion that does not apply the driving voltage is formed, characterized in that.

  In this ink jet recording head, when a driving voltage is applied to the piezo element, the driving portion is bent and deformed by a so-called bimorph effect. By this deformation, the ink chamber is expanded or compressed, and the ink in the ink chamber is ejected as ink droplets from the nozzle.

  The drive portion of the piezo element is polarized in a direction in which it is deformed by application of a drive voltage, but at least one of the diaphragm and the electrode plate is formed with a non-apply portion that does not apply the drive voltage to the electrode pad portion. . As a result, the electrode pad portion is not deformed when the drive voltage is applied, so that the internal force that the drive portion and the electrode pad portion attract each other can be made smaller than that of the conventional structure, and the force that easily restrains the deformation of the drive portion with a simple configuration. Is reduced, and the output displacement of the drive unit is increased.

  According to a ninth aspect of the present invention, the ink jet recording head according to any one of the first to eighth aspects is provided.

  That is, since the ink jet recording head according to any one of claims 1 to 8 is provided, the force with which the electrode pad of the piezo element restrains the bending deformation of the driving unit with a simple configuration is easily achieved. Is reduced, and the output displacement of the drive unit is increased.

  Since the present invention has the above configuration, the displacement constraint of the drive unit by the electrode pad portion of the piezo element can be easily reduced with a simple configuration, and a large output displacement can be obtained.

  1 and 2 partially show the ink droplet ejection portion of the inkjet recording head 112 according to the first embodiment of the present invention. FIG. 3 shows an ink jet recording apparatus 102 including the ink jet recording head 112. The ink jet recording apparatus 102 provided with the ink jet recording head 112 of the present embodiment ejects ink droplets of colored ink from a nozzle 140 (see FIGS. 1 and 2) of the ink jet recording head 112 onto a recording paper P that is a recording medium. It is used to record an image with dots formed by the ink droplets.

  As shown in FIG. 3, the inkjet recording apparatus 102 moves the carriage 104 on which the inkjet recording head 112 is mounted, and the carriage 104 in a predetermined main scanning direction along the recording surface of the recording paper P (main scanning). The main scanning mechanism 106 and the sub-scanning mechanism 108 for conveying (sub-scanning) the recording paper P in a predetermined sub-scanning direction that intersects (preferably orthogonally) the main scanning direction are configured. In the drawings, the main scanning direction is indicated by an arrow M, and the sub-scanning direction is indicated by an arrow S.

  The ink jet recording head 112 is mounted on the carriage 104 so that the nozzle surface on which the nozzles 140 are formed faces the recording paper P, and is moved in the main scanning direction by the main scanning mechanism 106 with respect to the recording paper P. By ejecting ink droplets, an image is recorded on a certain band region BE. When one movement in the main scanning direction is completed, the recording paper P is conveyed in the sub scanning direction by the sub scanning mechanism 108, and the next band area is recorded while moving the carriage 104 in the main scanning direction again. By repeating such an operation a plurality of times, image recording can be performed over the entire surface of the recording paper P.

  As can be seen from FIGS. 1 and 2, the inkjet recording head 112 is attached to the chamber plate 118, the nozzle plate 116 attached to one end face of the chamber plate 118, and the other end face of the chamber plate 118. The vibration plate 124 is included.

  The chamber plate 118 is formed with a plurality of chamber portions 118H, and the chamber portion 118H, the nozzle plate 116, and the vibration plate 124 constitute a plurality of ink chambers 142 that are temporarily filled with ink. Yes. That is, the chamber plate 118 forms a partition that separates the plurality of ink chambers 142, and the wall at one end in the thickness direction of the ink chamber 142 is formed by the nozzle plate 116 and the wall at the other end is formed by the diaphragm 124. Will be.

  In the nozzle plate 116, the nozzles 140 corresponding to the respective ink chambers 142 are formed. The nozzles 140 may be arranged in a line or a plurality of lines in the nozzle surface 114S, or may be a so-called matrix arrangement.

  A piezoelectric element 144 is attached to the diaphragm 124. The piezo element 144 includes a drive unit 144D disposed at a position corresponding to the ink chamber 142 and an electrode pad unit 144P disposed at a portion corresponding to the chamber plate 118 (a portion serving as a partition wall of the ink chamber 142). It is set as an integrated structure (these boundary surfaces are indicated by a two-dot chain line BS).

  An electrode plate 120 is disposed on the piezoelectric element 144 so as to face the vibration plate 124 with the piezoelectric element 144 interposed therebetween. This is usually a thin film electrode using sputtering or the like.

  As shown in detail in FIG. 1A, a first electrode portion 120A having substantially the same shape as that of the driving portion 144D in plan view is formed at the center of the electrode plate 120. Further, a portion corresponding to the boundary surface BS between the drive unit 144D and the electrode pad portion 144P of the piezo element 144 is independent (insulated) from the first electrode unit 120A along the shape of the boundary surface BS in plan view. ), The third electrode portion 120C is configured. 120 A of 1st electrode parts are comprised also in the location corresponding to electrode pad part 144P so that it may go around the both sides of this 3rd electrode part 120C. Therefore, the part corresponding to the drive part 144D and the part corresponding to the electrode pad part 144P of the first electrode part 120A are connected on both sides of the third electrode part 120C.

  Further, the outermost edge of the portion corresponding to the electrode pad portion 144P is formed by a substantially L-shaped fourth electrode portion 120D independently (insulated) from both the first electrode portion 120A and the third electrode portion 120C. Has been. The shape of this electrode is configured so as to be along a substantially constant distance from the third electrode portion. The third electrode portion 120C and the fourth electrode portion 120D constitute a polarization electrode pair 122B that can polarize the electrode pad portion 144P in the in-plane direction of the piezoelectric element, as will be described later. The diaphragm 124 also functions as the second electrode portion 120B, and the first electrode portion 120A and the second electrode portion 120B constitute a drive electrode pair 122A that can drive the drive portion 144D. . The second electrode portion 120B is an electrode (common electrode) common to the plurality of ink chambers 142, and the first electrode portion 120A is an electrode (individual electrode) corresponding to the ink chamber 142 of the second electrode portion 120B. However, the reverse is also possible.

  Further, the chamber plate 118 is formed with an ink channel 136 serving as a channel for the ink supplied from the ink supply channel 146. The ink flow path 136 is shared by the plurality of ink chambers 142, and the ink that has flowed through the ink flow path 136 is sent to the ink chamber 142 through the ink supply path 146.

  In the drawing, the chamber plate 118 is a single plate-shaped member, and the chamber 118H, the ink flow path 136, the ink supply path 146, and the like are formed therein. However, a plurality of plates are stacked. And the chamber plate 118 may be comprised as a whole.

  Next, in the process of manufacturing the ink jet recording head 112 of the present embodiment, the drive unit 144D and the electrode pad unit 144P of the piezo element 144 are polarized in desired directions, respectively, so that the first polarization unit 144A and the second polarization unit 144A of the present invention are used. A method of configuring the polarization unit 144B will be described.

  First, the nozzle plate 116, the vibration plate 124, the piezo element 144, and the electrode plate 120 are laminated and bonded to the chamber plate 118 to be integrated. A conventional general method can be applied to this process. . At this stage, the piezo element 144 is unpolarized, and the first polarization unit 144A and the second polarization unit 144B are not configured.

  Here, first, a predetermined polarization voltage is applied between the first electrode portion 120A and the second electrode portion 120B (the diaphragm 124), and the piezo element 144 is moved from the first electrode portion 120A to the second electrode portion 120B. Polarization is performed in the direction of heading (the thickness direction of the piezo element 144) (see arrow P1 in FIG. 1B). Thereby, 144 A of 1st polarization parts are comprised. At this time, the region of the electrode pad portion where the first electrode portion exists is also polarized in the same manner as the drive portion.

  Next, a predetermined polarization voltage is applied between the third electrode portion 120C and the fourth electrode portion 120D, and the electrode pad portion 144P moves in the direction from the third electrode portion 120C to the fourth electrode portion 120D (piezo element 144). (Refer to the arrow P2 in FIG. 1B). Thereby, the 2nd polarization part 144B is constituted. Note that the electrode pad portion 144P is also polarized in the thickness direction in the previous polarization step, but is corrected in the in-plane direction by this step. Here, since the distance between the third electrode part 120C and the fourth electrode part 120D is larger than the distance between the first electrode part 120A and the second electrode part 120B, it is necessary to increase the polarization voltage according to the distance. is there.

  As described above, in this embodiment, the electrode plate 120 is provided with the polarization electrode pair 122 </ b> B configured by the third electrode portion 120 </ b> C and the fourth electrode portion 120 </ b> D, and thus the piezoelectric element 144 is replaced with the diaphragm 124 and the electrode plate 120. The first polarization unit 144A and the second polarization unit 144B can be formed inside by polarizing in a desired direction in a state sandwiched between.

  Thereafter, individual electric wiring (not shown) is connected to the region where the first electrode portion 120A of the electrode pad portion 144P is present.

  In order to drive the ink jet recording head 112 configured as described above and eject ink droplets from the nozzles 140, only the driving electrode pair 122A (the first electrode portion 120A and the second electrode portion 120B) has an image. A driving voltage corresponding to the information is applied (see arrow D1 in FIG. 2A). As a result, as shown in FIG. 2A, the drive unit 144D (first polarization unit 144A) is flexibly deformed by the bimorph effect to vibrate the diaphragm 124. Ink droplets are ejected from the nozzle 140 by compressing the ink chamber 142. Further, when the ink chamber 142 is expanded, ink is supplied from the ink flow path 136 through the ink supply path 146 to the ink chamber 142.

  Here, in the present embodiment, the electrode pad portion 144P of the piezo element 144 is the second polarization portion 144B, and is polarized in a direction from the third electrode portion 120C to the fourth electrode portion 120D. Therefore, as shown in FIG. 2A, the electrode pad portion 144P is shear-deformed so as to be inclined toward the driving portion 144D by the application of the driving voltage. When the electrode pad portion 144P is also polarized in the same direction as the driving portion 144D as in the prior art, the electrode pad portion 144P and the driving portion 144D are attracted to each other by internal force when a driving voltage is applied, and the electrode pad portion 144P is driven. The deformation of the portion 144D is constrained. However, in this embodiment, since the restraining force of the deformation of the drive unit 144D by the electrode pad portion 144P is reduced, the output displacement of the drive unit 144D increases.

  4A and 4B show an inkjet recording head 412 of a comparative example (prior art) that is prepared for comparison and does not fall under the present invention. In the ink jet recording head 412, the electrode plate 420 is composed of only the first electrode portion 420A. In addition, the inside of the piezo element 444 is also polarized from the electrode plate 420 toward the diaphragm 424 uniformly throughout. Except for these, the configuration is the same as that of the first embodiment (note that the diaphragm 424 is not shown in FIG. 4A).

  In the inkjet recording head 412 of the comparative example, when the driving voltage is applied between the electrode plate 420 and the vibration plate 424 and the driving unit 444D is bent and deformed by the bimorph effect similarly to the first embodiment, the boundary surface BS The in-plane direction stress at 50 has reached 50 MPa. On the other hand, as shown in FIG. 2B, in the inkjet recording head 112 of the first embodiment, the in-plane stress at the boundary surface BS during driving remains at 26 MPa. Also from this example, it can be seen that in the present embodiment, the restraining force of the deformation of the drive unit 144D by the electrode pad unit 144P is reduced.

  FIG. 5 shows the effect of increasing the output displacement of the drive unit by comparing each embodiment of the present invention with the prior art. The relationship between the output displacement ratio and (bridge width / chamber width) is shown.

  As shown in FIG. 4A, the bridge width refers to the width of the narrowest part of the boundary between the drive part and the electrode pad part of the piezoelectric element, and the chamber width refers to the same direction as the bridge width. The width of the drive unit. As the ratio (bridge width / chamber width) increases, the electrode pad portion restrains the deflection deformation of the drive portion more strongly. 4A shows the bridge width and the chamber width in the case of the comparative example, these are similarly defined in each embodiment of the present invention.

  On the other hand, the “output displacement ratio” is an index when the value of (bridge width / chamber width) in the structure having the reference value 1.0 is the reference value 1.0, which is the conventional output displacement. The higher the value, the more efficiently the drive unit is driven.

  From this graph, it can be seen that in the range of 0.6 ≦ (bridge width / chamber width) ≦ 1.0, an output displacement ratio higher than that of the prior art is obtained in the present embodiment.

  6 and 7 show an ink jet recording head 212 according to a second embodiment of the present invention. In the second embodiment, the shape of the electrode plate is different from that of the first embodiment. However, all other configurations including the entire configuration of the ink jet recording apparatus are the same as those of the first embodiment. The elements and members are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the electrode plate 220 of the second embodiment, the third electrode portion 220C is divided and formed on both sides of the boundary surface BS, unlike the third electrode portion 120C of the first embodiment. Therefore, in the first electrode part 220A of the second embodiment, the part corresponding to the driving part 144D and the part corresponding to the electrode pad part 144P are connected at the part between the two third electrode parts 220C. Become.

  Also in the second embodiment having such a configuration, as in the first embodiment, first, with respect to the piezo element 144, a predetermined interval between the first electrode portion 220A and the second electrode portion 120B (the diaphragm 124) is set. A polarization voltage is applied to configure the first polarization portion 144A that is polarized in the direction from the first electrode portion 120A toward the second electrode portion 120B (see arrow P1). At this time, as in the first embodiment, the region of the electrode pad portion where the first electrode portion exists is also polarized in the same manner as the drive portion.

  Next, a second polarization unit that is polarized in a direction from the third electrode unit 220C toward the fourth electrode unit 120D by applying a predetermined polarization voltage between the third electrode unit 220C and the fourth electrode unit 120D. 144B is configured (see arrow P2).

  Accordingly, in the second embodiment, similarly to the first embodiment, when a drive voltage corresponding to image information is applied between the first electrode portion 120A and the second electrode portion 120B, the drive portion 144D portion (the first portion) Since the polarization portion 144A) is bent and deformed by the bimorph effect and vibrates the diaphragm 124, the ink chamber 142 is compressed and ink droplets are ejected from the nozzle 140. Further, since the electrode pad portion 144P (second polarization portion 144B) undergoes shear deformation so as to incline toward the drive portion 144D when a drive voltage is applied, the restraining force of deformation of the drive portion 144D by the electrode pad portion 144P is reduced. As a result, the output displacement of the drive unit 144D increases. As shown in FIG. 7B, also in the second embodiment, the in-plane stress at the boundary surface BS during driving remains at 26 MPa, and the restraining force of deformation of the driving unit 144D by the electrode pad unit 144P is limited. It turns out that it is reduced rather than a comparative example (refer FIG. 4).

  Further, from the graph of FIG. 5, in the range of 0.6 ≦ (bridge width / chamber width) ≦ 1.0, the second embodiment can obtain a higher output displacement ratio than the comparative example, similarly to the first embodiment. You can see that

  In the first embodiment and the second embodiment, the material of the piezo element 144 is a so-called hard system so that the polarization direction of the electrode pad portion 144P is not inadvertently changed by the drive voltage during driving. It is preferable to use these materials. From the same viewpoint, it is preferable to increase the polarization voltage when configuring the second polarization unit 144B, rather than the drive voltage.

  In addition, by using a piezoelectric element in which the drive unit 144D and the electrode pad unit 144P are polarized in a predetermined direction in advance, regardless of voltage application to the drive polarization pair 122A and the polarization electrode pair 122B in the manufacturing process, You may comprise the inkjet recording head of this invention.

  8 and 9 show an ink jet recording head 312 according to a third embodiment of the present invention. Also in the third embodiment, the same components and members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Also in the third embodiment, the overall configuration of the ink jet recording apparatus is the same as that of the first embodiment.

  In the electrode plate 320 of the third embodiment, unlike the first embodiment and the second embodiment, the third electrode portion and the fourth electrode portion are not configured. In other words, the electrode plate 320 includes only the first electrode portion 320A.

  In addition, the diaphragm 324 of the third embodiment has a hole 324H as a non-application portion formed in a portion corresponding to the electrode pad portion 144P, and the hole 324H is driven between the electrode plate 320 and the hole 324H. The electrode pair 122A is not configured. Note that the hole 324H is preferably filled with an insulating member (such as an adhesive).

  In this embodiment, when a piezo element polarized in a predetermined direction (thickness direction) is used in advance, the drive unit 344D and the electrode pad unit 344P of the piezo element 344 are both connected from the electrode plate 320 to the diaphragm 324. (Essentially, only the first polarization portion 144A of the first embodiment).

  In the third embodiment having such a configuration, when a drive voltage corresponding to image information is applied between the first electrode part 320A and the diaphragm 324, the drive part 344D is deformed by the bimorph effect and the diaphragm 324 is deformed. , The ink chamber 142 is compressed and ink droplets are ejected from the nozzles 140. In addition, since the hole 324H is formed in the diaphragm 324 of the third embodiment, the above driving voltage does not act on the electrode pad portion 344P, and the electrode pad portion 344P becomes piezoelectrically inactive. That is, even when the drive voltage is applied, the electrode pad portion 344P is not deformed. As a result, the restraining force of deformation of the drive unit 344D by the electrode pad unit 344P is reduced as compared with the prior art, so that the output displacement of the drive unit 344D increases. As shown in FIG. 9B, in the third embodiment, the in-plane stress at the boundary surface BS during driving is 37 MPa, and the restraining force of deformation of the driving unit 344D by the electrode pad unit 344P is a comparative example ( As can be seen from FIG.

  Further, it can be seen from the graph of FIG. 5 that an output displacement ratio higher than that of the comparative example is obtained in the range of 0.6 ≦ (bridge width / chamber width) ≦ 1.0.

  In the third embodiment, the non-application portion of the present invention may be formed on the electrode plate 320.

  In addition, the configuration in which the electrode pad portion is piezoelectrically inactive is not limited to this. For example, a configuration may be adopted in which only the inside of the electrode pad portion is in an unpolarized state.

  As described above, in any of the embodiments of the present invention, the force with which the electrode pad portion of the piezo element restrains the deflection deformation of the drive portion during driving is reduced, so that a large output displacement can be obtained.

  Further, since a drive voltage necessary for obtaining a desired output displacement can be reduced, the entire ink jet recording head can be driven with high efficiency, and the size can be reduced.

  In addition, in the conventional configuration, the internal force generated when the electrode pad portion itself tries to bend and deform by the same mechanism as that of the driving portion causes unnecessary vibration in the ink jet recording head, but this can also be prevented.

  Further, since the force (internal stress) acting on the piezo element is reduced, the reliability of adhesion of the piezo element to the vibration plate and electrode plate is improved and the life of the piezo element itself is also extended.

  As mentioned above, although embodiment of this invention was described, these embodiment showed embodiment suitable for this invention, and this invention is not limited to these. That is, various modifications, improvements, corrections, simplifications, and the like may be added to the above-described embodiment without departing from the gist of the present invention.

  Further, in the above description, the ink jet recording apparatus is configured to perform liquid droplet ejection while moving the ink jet recording head by the carriage. However, a line type liquid droplet ejection head in which the nozzles 140 are arranged over the entire width of the recording medium is used. It is also possible to apply the present invention to another apparatus configuration, such as performing printing while fixing only the recording medium while fixing the mold head (in this case, only main scanning is performed).

The inkjet recording head of 1st Embodiment of this invention is shown partially, (A) is a top view, (B) is the BB sectional drawing of (A). (A) And (B) is sectional drawing which shows partially the inkjet recording head of 1st Embodiment of this invention in a drive state. It is a perspective view which shows the inkjet recording device of this invention. The inkjet recording head of a comparative example is partially shown, (A) is a schematic perspective view, and (B) is a sectional view. It is a graph which shows the output change ratio in the inkjet recording head of this invention and a comparative example. The inkjet recording head of 2nd Embodiment of this invention is shown partially, (A) is a top view, (B) is the BB sectional drawing of (A). (A) And (B) is sectional drawing which shows partially the inkjet recording head of 2nd Embodiment of this invention in a drive state. The inkjet recording head of 3rd Embodiment of this invention is shown partially, (A) is a top view, (B) is the BB sectional drawing of (A). (A) And (B) is sectional drawing which shows partially the inkjet recording head of 3rd Embodiment of this invention in a drive state.

Explanation of symbols

102 Inkjet recording apparatus 104 Carriage 106 Main scanning mechanism 108 Sub scanning mechanism 112 Inkjet recording head 114S Nozzle surface 116 Nozzle plate 118 Chamber plate 118H Chamber portion 120 Electrode plate 120A First electrode portion 120B Second electrode portion 120C Third electrode portion 120D First 4 electrode part 122A drive electrode pair 122B polarization electrode pair 124 diaphragm 136 ink flow path 140 nozzle 142 ink chamber 144 piezo element 144D drive part 144P electrode pad part 144A first polarization part 144B second polarization part 146 ink supply path 154 Piezo actuator 212 Inkjet recording head 220 Electrode plate 220A First electrode portion 220C Third electrode portion 312 Inkjet recording head 320 Electrode plate 320A First electrode portion 32 4H Hole 324 Vibration plate 344 Piezo element 412 Inkjet recording head 420 Electrode plate 420A First electrode portion 424 Vibration plate 444 Piezo element 444D Drive unit BE Band area BS Boundary surface P Recording paper M Main scanning direction S Sub scanning direction

Claims (9)

A plurality of ink chambers filled with ink;
A nozzle communicating with the ink chamber to eject ink in the ink chamber as ink droplets;
A vibration plate disposed on an opening surface of the ink chamber to constitute a movable wall of the ink chamber, and to expand or compress the ink chamber by deformation;
Piezoelectric elements in which an electrode pad portion that is bonded to the diaphragm and disposed at a position corresponding to the chamber partition and a driving portion disposed at a position corresponding to the ink chamber are integrated;
An electrode plate that is arranged so as to sandwich a piezo element with the diaphragm and generates a driving voltage according to image information between the diaphragm and the diaphragm;
Have
The drive unit is a first polarization unit that is polarized in a direction in which it is deformed by application of the drive voltage,
The electrode pad portion is a second polarization portion that is polarized in a direction of shear deformation by application of the drive voltage.
An ink jet recording head. The first polarization part is polarized in the same direction as the voltage application direction of the drive voltage;
The inkjet recording head according to claim 1, wherein the second polarization portion is polarized in a direction substantially orthogonal to a voltage application direction of the drive voltage.   3. The ink jet recording head according to claim 2, wherein the polarization direction of the second polarization portion is a direction in which the electrode pad portion undergoes shear deformation toward the drive portion by application of the drive voltage.   3. The ink jet recording head according to claim 2, wherein a polarization direction of the second polarization portion is a direction from a boundary line between the electrode pad portion and the driving portion toward an outer periphery of the electrode pad portion. A pair of electrodes for polarization that applies a polarization voltage to polarize the electrode pad portion to form the second polarization portion on at least one of the electrode plate or the diaphragm;
The inkjet recording head according to claim 1, wherein the inkjet recording head is formed.   One of the electrode pairs for polarization is formed along a boundary line between the drive unit and the electrode pad unit, and the other is formed along a substantially constant distance from the other. The ink jet recording head according to claim 5. A plurality of ink chambers filled with ink;
A nozzle communicating with the ink chamber to eject ink in the ink chamber as ink droplets;
A vibration plate disposed on an opening surface of the ink chamber to constitute a movable wall of the ink chamber, and to expand or compress the ink chamber by deformation;
A piezoelectric element that is integrated with an electrode pad portion that is bonded to the diaphragm and is disposed at a position corresponding to the chamber partition, and a drive portion that is disposed at a position corresponding to the ink chamber;
An electrode plate that is arranged so as to sandwich a piezo element with the diaphragm and generates a driving voltage according to image information between the diaphragm and the diaphragm;
Have
The drive unit is a polarization unit that is polarized in a direction in which it is deformed by application of the drive voltage,
The electrode pad portion is a non-polarized portion;
An ink jet recording head. A plurality of ink chambers filled with ink;
A nozzle communicating with the ink chamber to eject ink in the ink chamber as ink droplets;
A vibration plate disposed on an opening surface of the ink chamber to constitute a movable wall of the ink chamber, and to expand or compress the ink chamber by deformation;
A piezoelectric element that is integrated with an electrode pad portion that is bonded to the diaphragm and is disposed at a position corresponding to the chamber partition, and a drive portion that is disposed at a position corresponding to the ink chamber;
An electrode plate that is arranged so as to sandwich a piezo element with the diaphragm and generates a driving voltage according to image information between the diaphragm and the diaphragm;
Have
The driving unit is polarized in a direction in which the driving unit bends and deforms when the voltage is applied;
At least one of the diaphragm and the electrode plate is formed with a non-application portion that does not apply the drive voltage to the electrode pad portion.
An ink jet recording head.   An ink jet recording apparatus comprising the ink jet recording head according to claim 1.

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