JP4665463B2 - Inkjet recording head - Google Patents

Description

  The present invention relates to an inkjet recording head that ejects droplets.

  A recording medium such as recording paper that selectively ejects ink droplets from a plurality of nozzles of an ink jet recording head that reciprocates in the main scanning direction (hereinafter sometimes simply referred to as “recording head”) and is conveyed in the sub-scanning direction. Inkjet recording apparatuses that print characters, images, and the like are conventionally known.

  The recording head includes a nozzle that ejects ink droplets, a chamber (so-called pressure chamber) that communicates with the nozzle and is filled with ink, a vibration plate that forms part of the chamber, and a pressure chamber that increases and decreases pressure through the vibration plate. And a single plate piezo actuator (so-called piezoelectric member, hereinafter referred to as “PA”).

  If the center of the PA drive section is deviated from the center of the chamber, the amount of displacement of the diaphragm will be different, the deformation characteristics of the diaphragm will be non-uniform, and variations in the ink ejection amount and ejection speed will occur within the recording head. growing. That is, the ink ejection characteristics are affected, and the ink ejection characteristics are degraded.

  As a general solution for preventing the deterioration of the ink ejection characteristics, a PA, and a flow path plate unit on the ink flow path side such as a vibration plate, a chamber plate constituting a chamber, and a nozzle plate on which a nozzle is formed are joined. (Hereinafter referred to as “PA bonding”), the PA bonding is performed while performing fine adjustment so that the center of the chamber and the center of the driving unit of the PA coincide with each other.

  On the other hand, in order to obtain improved ink ejection characteristics, in Patent Document 1, as shown in FIGS. 12A and 12B, pressure is applied to both ends of the piezoelectric layer 202 constituting the piezoelectric element 200 in the width direction. A tensile film 206 having a tensile stress is continuously provided on at least both sides in the width direction of the piezoelectric layer 202 and disposed in a region facing the generation chamber 204, and the tension of the tensile film 206 is applied to the piezoelectric layer 202. The piezoelectric characteristics are maintained.

  Furthermore, in Patent Document 2, as shown in FIGS. 13A and 13B, a piezoelectric element driving unit 212 is disposed in the chamber 210, and the chamber is arranged with respect to substantially the entire circumference of the outer peripheral side surface of the piezoelectric element driving unit 212. A gap is provided between the inner wall of 210 and the piezoelectric element driving unit 212 is disposed opposite to the chamber 210 to stabilize the deformation characteristics of the diaphragm 214 and improve the ink ejection performance.

  However, in Patent Document 1, the piezoelectric layer 202 and the tensile film 206 are integrally provided, and the tension of the tensile film 206 is simply used. Further, in Patent Document 2, the piezoelectric element driving unit 212 and the wiring unit 216 are integrally provided on the same plane, and when a voltage is applied to the voltage input terminal unit 218, the piezoelectric element driving unit of the wiring unit 216 is provided. 212 side will drive.

That is, these are to improve the ink discharge performance based on the condition that the center of the PA drive unit and the center of the chamber coincide with each other. There is a problem that a deviation occurs between the center of the chamber, and if this deviation is large, there is a variation in the deformation characteristics of the diaphragm, resulting in a decrease in ink ejection characteristics.
JP 2000-141644 A JP 2001-260352 A

  In consideration of the above facts, an object of the present invention is to obtain an ink jet recording head that suppresses variations in deformation characteristics of a diaphragm and prevents variations in ink ejection characteristics.

In order to achieve the above-mentioned object, the invention according to claim 1 is arranged in a matrix, and a plurality of nozzles for discharging droplets, a plurality of pressure chambers communicating with the nozzles and filled with ink, A diaphragm constituting a part of the pressure chamber, an electric pad portion arranged at a position not corresponding to the pressure chamber and bonded to an electric substrate, and arranged at a position corresponding to the pressure chamber, the electric pad portion A plurality of piezoelectric members having a deforming portion that is deformed by a voltage applied to the pressure chamber and displaces the diaphragm in the pressure chamber, and each of the plurality of piezoelectric members is adjacent to each other in the first direction of the matrix and the first on both sides in a second direction perpendicular to the direction, provided at a corresponding piezoelectric element and a gap, with each other in shape they are the same, provided with a gap to each other, each end when projected in a plan view Part To project a plurality of the pressure chamber, and having a plurality of dummy piezoelectric member to which the voltage is not applied, the.

  According to the first aspect of the present invention, the pressure chamber communicating with the nozzles arranged in a matrix shape is filled with ink. A piezoelectric member such as a single-plate piezo actuator is provided in a matrix on the surface of the diaphragm that constitutes a part of the pressure chamber. When a voltage is applied to the piezoelectric member, the diaphragm is displaced in the pressure chamber. To do. Further, a dummy piezoelectric member is provided on the surface of the diaphragm with a gap around the piezoelectric member, and the end of the dummy piezoelectric member protrudes into the pressure chamber when projected in plan view.

  Thus, by providing a gap between the dummy piezoelectric member and the piezoelectric member, the dummy piezoelectric member is completely independent from the piezoelectric member. For this reason, the dummy piezoelectric member is not affected at all by the application of the voltage of the piezoelectric member. In other words, in the region where the dummy piezoelectric member is disposed, the diaphragm does not displace. When a voltage is applied to the piezoelectric member and the piezoelectric member is displaced, the vibration fixed end when the diaphragm vibrates is the dummy piezoelectric member. It becomes the end of the member.

  Here, when projected in plan view, the end of the dummy piezoelectric member is projected into the pressure chamber, so that the vibration fixed end is in the pressure chamber even if the joining position of the piezoelectric member is somewhat shifted. Therefore, the deformation characteristics of the diaphragm are kept constant, the volume change rate in the pressure chamber is constant, and variations in ink ejection characteristics can be prevented.

  Also, by providing a dummy piezoelectric member around the piezoelectric member, when a substrate (PA substrate) on which the piezoelectric member has been previously patterned is bonded to the diaphragm, the bonding pressure is also distributed to the dummy piezoelectric member. Stress concentration on the surface is avoided.

  For this reason, it is possible to prevent the cause of deterioration of the ink ejection characteristics, such as cracks and cracks in the piezoelectric member, which are caused by the concentration of stress on the piezoelectric member. Furthermore, by projecting the end of the dummy piezoelectric member into the pressure chamber when projected in plan view, the piezoelectric member is disposed in the pressure chamber, so the PA substrate is bonded to the diaphragm. In this case, the stress at the time of joining is received by the dummy piezoelectric member, and no stress is applied to the piezoelectric member.

  Also, by providing a gap around the piezoelectric member, it is possible to absorb the difference in linear expansion coefficient between the piezoelectric member and the diaphragm when the PA substrate is joined to the diaphragm.

  According to a second aspect of the present invention, in the ink jet recording head according to the first aspect, the piezoelectric members have the same shape.

  In the second aspect of the invention, by making the shape of the piezoelectric member the same, the displacement amount of the diaphragm displaced by the piezoelectric member can be made the same for each nozzle, and the ink ejection performance is made uniform. Can do.

  Since the present invention is configured as described above, in the first aspect of the present invention, when the gap is provided between the dummy piezoelectric member and the piezoelectric member and projected in a plan view, the end of the dummy piezoelectric member is pressed against the pressure. By projecting into the chamber, the vibration fixed end is in the pressure chamber even if the joining position of the piezoelectric member is slightly shifted. Therefore, the deformation characteristics of the diaphragm are kept constant, the volume change rate in the pressure chamber is constant, and variations in ink ejection characteristics can be prevented.

  In addition, by providing a dummy piezoelectric member on the same plane as the piezoelectric member, when bonding a substrate (PA substrate) on which the piezoelectric member is pre-patterned to the diaphragm, the bonding pressure is also distributed to the dummy piezoelectric member, Stress concentration on the piezoelectric member can be avoided, and the cause of a decrease in ink ejection characteristics, such as cracking or cracking of the piezoelectric member, can be prevented.

  According to the second aspect of the present invention, the displacement amount of the diaphragm displaced by the piezoelectric member can be made the same for each nozzle, and the ink ejection performance can be made uniform.

  In the third aspect of the invention, the support conditions for supporting the piezoelectric element can be made substantially the same for each nozzle, and the ink ejection performance can be made more uniform.

  Hereinafter, the ink jet recording head according to the embodiment of the present invention will be described. First, an outline of the ink jet recording apparatus 70 shown in FIG. 1 will be described.

  The recording medium is a recording paper P, the conveyance direction of the recording paper P in the inkjet recording apparatus 70 is represented by an arrow S as a sub-scanning direction, and the direction perpendicular to the conveyance direction is represented by an arrow M as a main scanning direction.

  The ink jet recording apparatus 70 includes a carriage 76 on which black, yellow, magenta, and cyan ink jet recording units 72 are mounted. A pair of brackets 78 project from the carriage 76 on the upstream side in the conveyance direction of the recording paper P, and the bracket 78 has a circular opening 78A. A shaft 80 installed in the main scanning direction is inserted through the opening 78A.

  A driving pulley 84 and a driven pulley 86 constituting the main scanning mechanism 82 are disposed at both ends in the main scanning direction. A timing belt 88 is wound around the driving pulley 84 and the driven pulley 86. The timing belt 88 is fixed to a carriage 76, and the carriage 76 can reciprocate in the main scanning direction.

  In addition, the inkjet recording apparatus 70 is provided with a sub-scanning mechanism 94 including a transport roller 90 and a discharge roller 92, and one sheet from a paper feed tray 96 on which recording paper P before image printing is placed in a bundle. The recording sheets P fed one by one are conveyed in the sub-scanning direction at a predetermined pitch.

  Further, as shown in FIG. 2, each color ink jet recording unit 72 includes an ink jet recording head 74 and an ink tank 98 that supplies ink thereto, and is formed on the lower surface of the ink jet recording head 74. The plurality of nozzles 10 (see FIG. 4B) are mounted on the carriage 76 so as to face the recording paper P.

  Accordingly, the ink jet recording head 74 selectively ejects ink droplets from the nozzles 10 to the recording paper P while moving in the main scanning direction by the main scanning mechanism 82 (see FIG. 1), whereby a predetermined band region BE is obtained. In contrast, a part of the image based on the image data is recorded.

  When one movement in the main scanning direction is completed, the recording paper P is conveyed at a predetermined pitch in the sub scanning direction by the sub scanning mechanism 94 (see FIG. 1), and again the ink jet recording head 74 (ink jet recording unit 72). Is moving in the main scanning direction (the direction opposite to the above), and a part of the image based on the image data is recorded in the next band area, and this operation is repeated a plurality of times. Thus, the entire image based on the image data is recorded on the recording paper P in full color.

  Next, the configuration of the ink jet recording head according to the embodiment of the present invention will be described.

  As shown in FIGS. 3A and 3B, the inkjet recording head 74 is provided with a common ink chamber 20 to which ink is supplied from an ink tank 98 (see FIG. 2). An opening 18 is provided in the common ink chamber 20, and the pressure chamber 14 communicates with the ink supply path 16 so that ink in the common ink chamber 20 is supplied.

  The inkjet recording head 74 includes a plurality of nozzles 10 arranged in a matrix and communicates with the pressure chamber 14 via the nozzle communication chamber 12. A vibration plate 30 having elasticity in the vertical direction is provided on the upper surface of the pressure chamber 14. On the upper surface of the vibration plate 30 corresponding to the pressure chamber 14, as shown in FIG. Arranged in a shape.

  The piezoelectric active portions 42 all have the same shape, and as shown in FIG. 4A, rhomboid pressure chambers in which the four corners are formed by arcs and the ratio of the lengths of the two diagonals is close to 1. 14 is formed so as to be slightly smaller than 14, and on the longer diagonal L of the two rhombuses 42A located above the pressure chamber 14 and the rhombus 42A, the corners of the rhombus 42A overlap. And a polygonal portion 42B formed integrally.

In this polygonal part 42B, the side m ₁ connected to the rhombus 42A spreads away from the rhombus 42A. Further, the side m ₂ facing the nozzle 10 located in the pressure chamber 14 in plan view is formed perpendicular to the diagonal L at a position away from the pressure chamber 14. The side m ₁ and the side m ₂ of the polygonal part 42B are connected by a curved part that protrudes toward the corner part 14A of the pressure chamber 14.

  The polygonal part 42B becomes an electric pad part for electrical connection, and the electric substrate 36 is joined via the ball solder 34. When a voltage is applied to the polygonal portion 42B, the diamond-shaped portion 42A located above the pressure chamber 14 is deformed by electrostriction and becomes a drive portion that pressurizes the ink in the pressure chamber 14. As described above, when the ink in the pressure chamber 14 is pressurized, an ink droplet is ejected from the nozzle 10.

As shown in FIG. 5, a dummy portion 44 is provided on the same plane as the piezoelectric active portion 42 at the center of the region where the piezoelectric active portions 42 are arranged in 2 rows × 2 columns.
A dummy portion 44 having the same shape is arranged around the piezoelectric active portion 42. A groove 40 is provided between the dummy portion 44 and the piezoelectric active portion 42. Here, as shown in FIG. 4A, the end portion (hatched portion) of the dummy portion 44 is arranged above the pressure chamber 14.

  Next, a method for manufacturing the ink jet recording head according to the embodiment of the present invention will be described.

  As shown in FIG. 6A, the ink jet recording head 74 includes a nozzle plate 21 in which the nozzles 10 are formed, an ink pool plate 22 that forms the nozzle communication chamber 12 and the common ink chamber 20, and an ink pool plate 23. A through plate 24 that forms the opening 18 of the common ink chamber 20 and the nozzle communication chamber 12, an ink supply path plate 26 in which the ink supply path 16 is formed, and a pressure chamber plate 28 in which the pressure chamber 14 is formed. Are laminated and joined in order.

  The surface of the nozzle plate 21 is covered with a water-repellent coating film, and the nozzle 10 is formed by the excimer laser 50 as shown in FIG. 6B. As shown in FIG. After the formation, the diaphragm 30 is bonded to the pressure chamber plate 28.

  The material of the nozzle plate 21 is polyimide, and the material of the ink pool plate 22, the ink pool plate 23, the through plate 24, the ink supply path plate 26, the pressure chamber plate 28, and the vibration plate 30 is SUS.

  The nozzle plate 21, the ink pool plate 22, the ink pool plate 23, the through plate 24, the ink supply path plate 26, the pressure chamber plate 28, and the vibration plate 30 are bonded to each other. That's it.

  Here, separately, as shown in FIG. 6D, a piezoelectric unit 54 (hereinafter referred to as “PA substrate 54”) including a piezoelectric active portion 42 to which a voltage is applied and a dummy portion 44 to which no voltage is applied. ).

  First, a piezoelectric plate 58 and a fixed substrate 56, which will be described later, are bonded via an adhesive. For the bonding, a peelable adhesive, for example, a heat-foamable adhesive film having a property of foaming and greatly reducing the adhesive strength when heated at a predetermined temperature after bonding is used.

  After the piezoelectric plate 58 is bonded and fixed to the fixed substrate 56, a groove 40 having a constant width is formed in the piezoelectric plate 58 using sand blast processing, which will be described later, so that piezoelectric active elements arranged in a matrix as shown in FIG. A PA substrate 54 on which the part 42 and the dummy part 44 are formed is created.

  The opposite surface of the PA substrate 54 to which the fixed substrate 56 is bonded is bonded to the diaphragm 30 of the flow path plate unit 52 (hereinafter referred to as “PA bonding”). The alignment at the time of PA bonding is performed by aligning marks (not shown) formed in advance on the flow path plate unit 52 and marker holes (not shown) previously formed on the fixed substrate 56.

  Although not shown in the drawings, the first electrode layer (lower surface) and the second electrode layer (upper surface) are formed in advance on both surfaces of the piezoelectric plate 58 by sputtering or the like, and the diaphragm also serves as a common electrode. The piezoelectric active part 42 and the diaphragm 30 are also electrically connected through the first electrode layer by bonding with the adhesive 30.

  Then, the fixed substrate 56 is heated to reduce the adhesive force of the thermally foamable adhesive film, and the fixed substrate 56 is peeled off (see FIG. 6E). As shown in FIG. A ball solder 34 is formed for each 42, and an electric substrate 36 is bonded thereon.

  As described above, since the second electrode layer is formed on the upper surface of the piezoelectric plate 58, the piezoelectric active portion 42 and the electric substrate 36 are electrically connected via the second electrode layer. Further, the electric board 36 and the diaphragm 30 are connected by a contact (not shown).

  Finally, an ink supply member or the like (not shown) is attached to complete the ink jet recording head 74 of the present embodiment.

  Ink is introduced from the ink tank 98 (see FIG. 2) into the ink jet recording head 74 thus completed, and flows along the arrow Y as shown in FIGS. 3 (B) and 4 (B). The common ink chamber 20, the ink supply path 16, the pressure chamber 14, and the nozzle communication chamber 12 are filled.

  By the way, in the present embodiment, when the piezoelectric active portion 42 and the dummy portion 44 are formed on the piezoelectric plate 58, that is, when the groove portion 40 having a constant width is formed on the piezoelectric plate 58, such a sandblasting process is used. Complex shapes of the piezoelectric active part 42 and the dummy part 44 can be manufactured. Therefore, sandblasting will be described below.

  As shown in FIG. 7 (note that the shapes of the piezoelectric active portion 42 and the dummy portion 44 are simply shown here), a piezoelectric material block (not shown) is first lapped to produce a piezoelectric plate 58. . The thickness of the piezoelectric plate 58 is determined based on the amount of deflection deformation and the driving voltage required for the piezoelectric active part 42. In this embodiment, the thickness is 35 μm.

  A first electrode layer (lower surface) and a second electrode layer (upper surface) are formed on both surfaces of the piezoelectric plate 58 by sputtering or the like. In this embodiment, chromium, nickel, and gold are used as the electrode layer material.

  Subsequently, the sputtered piezoelectric plate 58 is temporarily fixed to the fixed substrate 56 through the thermally foamable adhesive film. A marker hole (not shown) is formed in the fixed substrate 56 for aligning the joining position with the flow path plate unit 52 (see FIG. 6D).

  A photosensitive film resist 60 is pasted on the temporarily fixed piezoelectric plate 58. In this embodiment, a urethane film resist having a thickness of 50 μm is used. Thereafter, an exposure mask 62 having a pattern through which ultraviolet rays (UV) are transmitted only through the piezoelectric active portion 42 and the dummy portion 44 is separately prepared and attached to the film resist 60.

  The exposure mask 62 is patterned with reference to the marker hole of the fixed substrate 56. The piezoelectric plate 58 covered with the film resist 60 is irradiated with UV through the exposure mask 62 and then etched. As the etching solution, an etching solution that does not remove the UV-irradiated portion and that can reliably remove other portions, for example, an aqueous sodium carbonate solution is used.

  By the above process, the film resist 60 is covered only on the piezoelectric active portion 42 and the dummy portion 44, and the film resist 60 is removed on the other portions. That is, the removed portion becomes a groove 40 having a constant width.

  Subsequently, sandblasting is performed. In this sandblasting process, the exposed portion (groove portion 40) of the piezoelectric plate 58 from which the film resist 60 has been removed is surely ground and removed, and the remaining portion of the film resist 60 (the piezoelectric active portion 42 and the dummy portion 44) is removed. Is performed under conditions that prevent grinding.

  Generally, in sandblasting, blasting abrasive grains collide with the side surface of the piezoelectric plate 58, so that the processing (vertical processing) in the thickness direction of the piezoelectric plate 58 progresses in the width direction of the piezoelectric plate 58. Processing (horizontal processing) also proceeds. The processing speed of this horizontal processing depends on the width of the groove 40 formed in the piezoelectric plate 58. That is, as the width of the groove portion 40 increases, the blast abrasive grains easily collide with the side surface of the piezoelectric plate 58, and the processing speed of horizontal processing increases.

  However, in the present embodiment, since the groove portion 40 has a constant width, the side etching amount is the same. For this reason, the piezoelectric active part 42 can be made into a uniform dimension, and a highly accurate process is attained. Then, after sandblasting, the film resist 60 remaining on the surface of the piezoelectric plate 58 is removed and washed.

  The upper film resist 60 is removed in this way, and the surface opposite to the fixed substrate 56, that is, the surface from which the film resist 60 is removed is attached to the diaphragm 30 as described above.

  Through the above steps, a PA substrate 54 having a piezoelectric active portion 42 and a dummy portion 44 which are attached to the fixed substrate 56 with a heat-foamable adhesive film and having electrode layers on both sides is obtained (see FIG. 7).

  As described above, according to the sandblasting, even the complicatedly shaped piezoelectric active part 42 and dummy part 44 as in the present embodiment can be processed easily and accurately in a short time. Therefore, the cost can be reduced.

  Next, the operation of the ink jet recording head according to the embodiment of the present invention will be described.

  In the present invention, as shown in FIGS. 4A and 4B, the piezoelectric active portion 42 is composed of a rhombus portion 42A and a polygonal portion 42B, and an electric substrate 36 is joined to the polygonal portion 42B via a ball solder 34. In addition, the rhombus 42A is deformed by electrostriction to serve as a drive unit that pressurizes the ink in the pressure chamber 14.

  As shown in FIG. 5, the piezoelectric active portions 42 are arranged in a matrix, and the central portion of the region where the piezoelectric active portions 42 are arranged in 2 rows × 2 columns is flush with the piezoelectric active portion 42. A dummy portion 44 is provided, and as shown in FIG. 4A, the end portion (hatched portion) of the dummy portion 44 is positioned above the pressure chamber 14 (projects into the pressure chamber 14). A groove 40 is provided between the piezoelectric active part 42 and the dummy part 44.

  As described above, by providing the groove portion 40 between the dummy portion 44 and the piezoelectric active portion 42, the dummy portion 44 is completely independent from the piezoelectric active portion 42. For this reason, the dummy part 44 is not affected at all by the voltage application of the piezoelectric active part 42.

  That is, as shown in FIG. 8A, the diaphragm 30 is not displaced in the region where the dummy portion 44 is disposed, and the rhombus 42A of the piezoelectric active portion 42 is applied by applying a voltage to the piezoelectric active portion 42. When displaced, the vibration fixed end P when the diaphragm 30 vibrates becomes the end portion of the dummy portion 44.

  By projecting the end portion of the dummy portion 44 into the pressure chamber 14 when projected in a plan view, even if the joining position of the piezoelectric active portion 42 is slightly shifted, the vibration fixed end P remains at the pressure chamber 14. The diaphragm 30 is always displaced in the pressure chamber 14. Therefore, the deformation characteristics of the diaphragm 30 are kept constant, and variations in ink ejection characteristics can be prevented.

  Further, for example, as shown in FIGS. 9A and 9B, when the dummy portion 44 is not provided around the piezoelectric active portion 42, the vibration of the fixed substrate 56 of the PA substrate 54 and the flow path plate unit 52. At the time of PA bonding for bonding the plate 30, stress concentrates on the piezoelectric active portion 42.

  On the other hand, as shown in FIGS. 10A and 10B, by providing a dummy portion 44 around the piezoelectric active portion 42, when the PA substrate 54 is bonded to the diaphragm 30, the stress at the time of bonding is the dummy portion. 44 is also dispersed, and stress concentration on the piezoelectric active part 42 is avoided. For this reason, it is possible to prevent the occurrence of a decrease in ink ejection characteristics, such as cracks and cracks in the rhombus 42A due to stress concentration on the piezoelectric active portion 42.

  Further, by projecting the end portion of the dummy portion 44 into the pressure chamber 14 when projected in plan view, the rhombus portion 42A of the piezoelectric active portion 42 is disposed in the pressure chamber 14. Become. For this reason, when the PA substrate 54 is bonded to the diaphragm 30, the stress at the time of bonding is received by the dummy portion 44, and no stress is applied to the rhombus portion 42A.

  Furthermore, by providing the groove portion 40 around the piezoelectric active portion 42, it is possible to absorb a difference in linear expansion coefficient between the PA substrate 54 and the diaphragm 30 during PA bonding.

  Further, by making the piezoelectric active portions 42 arranged in a matrix on the upper surface of the vibration plate 30 in the same shape, the displacement amount of the vibration plate 30 displaced by the piezoelectric active portion 42 can be made the same in each nozzle 10. Ink ejection performance can be made uniform. Furthermore, by making the shapes of the dummy portions 44 the same, the support conditions for supporting the piezoelectric active portion 42 can be made substantially the same for each nozzle 10, and the ink ejection performance can be made more uniform.

Here, as shown in FIGS. 8A and 8B, the protrusion amount L ₁ of the end portion of the dummy portion 44 into the pressure chamber 14 is used as the PA substrate when the PA substrate 54 and the diaphragm 30 are joined. 54 is larger than the positional shift amount L ₂ . For example, as shown in FIGS. 11A and 11B, when the center portion of the piezoelectric active portion 220 and the center portion of the pressure chamber 222 are displaced, the deformation characteristics of the diaphragm 224 are changed.

However, as shown in FIGS. 9A and 9B, the protrusion amount L ₁ of the end portion of the dummy portion 44 into the pressure chamber 14 is the amount of displacement when the PA substrate 54 and the diaphragm 30 are joined. By making it larger than L ₂ , even if the central portion of the rhombus 42A and the central portion of the pressure chamber 14 are displaced, the vibration fixed end P is always located in the pressure chamber 14.

Specifically, if the clearance between the end face on the side of the piezoelectric active portion 42 and the end face on the side of the dummy portion 44 (width of the groove portion 40) is all constant within the ink jet recording head 74, the optimum clearance value is created by blasting. Considering what to do, it is between 50 and 120 μm. For this reason, the projection amount L ₁ of the end portion of the dummy portion 44 into the pressure chamber 14 is an optimum value between 10 and 50 μm from the results of the PA bonding position deviation.

  As a result, the deformation characteristics of the diaphragm 30 that is unstable due to the displacement of the PA substrate 54 with respect to the center of the pressure chamber 14 become stable characteristics that are not affected by the displacement, and the displacement amount of the diaphragm 30 is constant. Kept. Accordingly, the volume change rate in the pressure chamber 14 is constant, and variations in ink ejection characteristics can be prevented.

  Further, in the ink jet recording apparatus 70 of the above embodiment, black, yellow, magenta, and cyan ink jet recording units 72 are mounted on the carriage 76, and the ink jet recording heads 74 of these colors are selectively selected based on image data. Although ink droplets are ejected and a full-color image is recorded on the recording paper P, ink jet recording in the present invention is not limited to recording characters and images on the recording paper P.

  That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrially used liquids such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging welded solder onto a substrate The ink jet recording head 74 according to the present invention can be applied to all droplet ejecting apparatuses.

  Further, in the ink jet recording apparatus 70 of the above embodiment, the example of the partial width array (PWA) having the main scanning mechanism 82 and the sub scanning mechanism 94 has been described. However, the ink jet recording in the present invention is not limited to this, and the paper width A corresponding so-called Full Width Array (FWA) may be used. Rather, since the present invention is effective for realizing a high-density nozzle arrangement, it is suitable for FWA that requires one-pass printing.

1 is a perspective view showing an ink jet recording apparatus to which an ink jet recording head according to an embodiment of the present invention is applied. 1 is a perspective view showing an ink jet recording unit to which an ink jet recording head according to an embodiment of the present invention is applied. (A) is a perspective view which shows the structure of the inkjet recording head based on Embodiment of this invention, (B) is the elements on larger scale of (A). (A) is an enlarged view showing a piezoelectric active portion of the ink jet recording head according to the embodiment of the present invention, and (B) is a cross-sectional view taken along line AA of (A). FIG. 2 is a plan view showing a piezoelectric active part and a dummy part of the ink jet recording head according to the embodiment of the invention. (A)-(F) is process drawing which represents typically the manufacturing process of the ink jet recording head concerning an embodiment of the invention. It is process drawing which represents typically the process of the sandblasting to the piezoelectric plate of the inkjet recording head of this Embodiment. (A) and (B) are BB sectional views of Drawing 4 (A), and are explanatory views showing a vibration fixed end of a diaphragm. (A), (B) is sectional drawing which shows the comparative example of the inkjet recording head which concerns on embodiment of this invention. (A), (B) is BB sectional drawing of FIG. 4 (A), and is explanatory drawing corresponding to FIG. (A), (B) is sectional drawing which shows the comparative example of the inkjet recording head which concerns on embodiment of this invention, and is explanatory drawing corresponding to FIG. (A), (B) is sectional drawing which shows the conventional inkjet recording head (patent document 1). FIG. 2A is a plan view showing a conventional inkjet recording head, and FIG. 2B is a cross-sectional view (Patent Document 2).

Explanation of symbols

10 Nozzle 14 Pressure chamber 30 Diaphragm 40 Groove (gap)
42 Piezoelectric active part (piezoelectric member)
44 Dummy part (dummy piezoelectric member)
70 Inkjet recording device 72 Inkjet recording unit 74 Inkjet recording head

Claims (2)

A plurality of nozzles arranged in a matrix and ejecting droplets;
A plurality of pressure chambers communicating with the nozzle and filled with ink;
A diaphragm constituting a part of the pressure chamber;
An electric pad portion disposed at a position not corresponding to the pressure chamber and bonded to an electric substrate; a vibration plate disposed at a position corresponding to the pressure chamber and deformed by a voltage applied to the electric pad portion; A plurality of piezoelectric members having a deforming portion that displaces
Each of the plurality of piezoelectric members is provided on both sides in the first direction of the matrix and on both sides in the second direction orthogonal to the first direction with a gap from the piezoelectric member, and the shape is the same. with it, provided with a gap to each other, each of the end portions when projected in a plan view is projected to a plurality of said pressure chamber, and a plurality of dummy piezoelectric member to which the voltage is not applied,
An inkjet recording head comprising:   The inkjet recording head according to claim 1, wherein the piezoelectric members have the same shape.

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