JP2007168337A - Ink-jet head and recording device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small ink-jet head which dispenses with the setting of the positioning precision of a piezoelectric element to a half or less of a nozzle pitch, dispenses with the dimensional precision of the piezoelectric element itself, and require no space corresponding to a space for two heads even if two nozzle rows are provided therefor. <P>SOLUTION: At least one pressure generating chamber out of a group of the pressure generating chambers in a chamber plate, and at least one piezoelectric oscillator out of a group of the piezoelectric oscillators of a piezoelectric actuator are arranged in a staggered or opposed manner with the nozzle row or a midpoint between the nozzle rows as the center, and the group of the pressure generating chambers and the group of the piezoelectric oscillators are held at least by one fixing member in a staggered manner. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head that forms an ink image on a print medium by applying pressure to ink using a piezoelectric vibrator formed by processing a piezoelectric element on a bulk to cause ink droplets to fly from a nozzle.

  Currently, there is an increasing demand for inkjet printers that achieve both high-speed printing and high-quality printing. Particularly for high-speed printing, it is more advantageous to use a line-type head unit that forms and prints an image in one pass parallel to the print medium, as compared to a serial ink jet printer.

  A thermal (heater heating) type inkjet printer (see, for example, Patent Document 1) that converts electric energy for ejecting ink into thermal energy and causes the thermal energy to act on ink as a line type is long. Although there is no dimensional restriction at the part level for the other line printers, it can be manufactured relatively easily, but the heating performance deteriorates due to the formation of deposits called kogation on the heater during ink heating. Discharge characteristics are reduced, and it is difficult to extend the life of the head. Further, there is a problem that a droplet medium to be discharged is limited.

  In addition to the above thermal ink jet printers, there is also known a laminated piezoelectric element method (for example, see Patent Document 2) that ejects ink droplets using laminated piezoelectric elements. However, the above-described multilayer piezoelectric element causes variations in longitudinal warpage, waviness, deformation, and crystal orientation in the cross section, and thus in-plane uniformity of piezoelectric characteristics cannot be obtained sufficiently, and the piezoelectric characteristics vary. There are problems such as. Such a problem becomes more prominent as the thickness of the piezoelectric element increases and the substrate size increases. Considering such a problem, the maximum length in the nozzle arrangement direction in which a piezoelectric element on the bulk can be manufactured is 60 mm.

  As an example in which an inkjet head using the above-described laminated piezoelectric vibrator is adapted to a line-type printer, an inkjet printer configured by fixing a plurality of head units on a single base (for example, Patent Documents) 3) is known. However, the above-described method requires high-precision positioning in the nozzle arrangement between the units of the head unit, and there is a difficulty in arranging high-density nozzles. In addition, the area of the partition walls at both ends of the housing holding the flow path plate is reduced, making it difficult to form the head unit itself, and the discharge characteristics are also degraded at both ends of the unit.

  In order to solve the positioning problem between the nozzles at both ends of the head unit as described above, a method of arranging a plurality of head units in a staggered manner (for example, see Patent Documents 4 and 5) is known. However, the above-described two-point arrangement method causes a problem that the head unit in the nozzle row orthogonal direction becomes large.

  In order to solve such a problem, as a method for realizing a line head as a single head unit using laminated piezoelectric elements, piezoelectric elements on a bulk are arranged in a line on a single base substrate. By joining the seam area between the nozzles at a position that is a multiple of the nozzle density pitch and processing the seam area when the piezoelectric vibrator is formed, the discharge at both ends of the piezoelectric element on the bulk is uniform. There is known an ink jet head for a line printer that does not require a nozzle arrangement between formed piezoelectric vibrators (see, for example, Patent Document 6). However, as the nozzle density of the inkjet head increases, the gap in the joint area of the piezoelectric elements on the bulk needs to be positioned within ½ of the nozzle pitch. It becomes expensive and difficult. Further, the longer the piezoelectric elements are arranged, the larger the accumulated error of the absolute position lengths of the piezoelectric elements on the bulk, and it becomes difficult to make the joint area of the piezoelectric elements a processing region. Therefore, a highly accurate dimensional tolerance is required for the piezoelectric element itself on the bulk, which increases the cost. In addition, the length of the piezoelectric element must be designed so as to be a multiple of the nozzle pitch, and the piezoelectric element must be designed for each development head, and parts cannot be shared.

  As a method for solving the above problem, there is a method (for example, refer to Patent Document 7) in which the both ends of each channel row are overlapped in a zigzag pattern. However, the method described above also increases the size of the head as in Patent Documents 4 and 5.

JP 2000-255064 A

JP-A-63-295269

Japanese Examined Patent Publication No. 3-58917

JP 2004-209964 A

Japanese Patent No. 2752843

Japanese Patent No. 3156411

Japanese Patent Laid-Open No. 2005-193602

  The present invention does not require the positioning accuracy of the piezoelectric element as described above to be 1/2 or less of the nozzle pitch, and does not require the dimensional accuracy of the piezoelectric element itself, and has two nozzle rows, An object of the present invention is to provide a small inkjet head that does not require space for two heads.

  The present invention provides an orifice plate having a plurality of nozzles for ejecting ink droplets, a chamber plate having a pressure generation chamber communicating with the nozzle, a diaphragm plate for sealing the pressure generation chamber, and the diaphragm plate through the diaphragm plate. In an inkjet head having a plurality of piezoelectric actuators composed of a plurality of piezoelectric vibrators for changing the volume of the pressure generating chamber, in at least one pressure generating chamber group of the chamber plate, at least one piezoelectric vibrator of the piezoelectric actuator The pressure generation chambers in the group and the piezoelectric vibrators are arranged in a staggered or opposed manner around a nozzle row or the middle of the nozzle row, and the plurality of pressure generation chamber groups and the piezoelectric vibrator groups are at least one fixing member It is characterized by being held in a staggered pattern.

  According to the present invention, since it corresponds to a full-line print head using piezoelectric elements, there is little variation in characteristics between nozzle units and between joints of piezoelectric elements, positioning accuracy between unit nozzles is not required, and piezoelectric on the bulk is also required. It is possible to provide an ink jet head with good workability that does not require precise positioning accuracy in the arrangement of elements and enables high-density mounting and high nozzle arrangement. In addition, the pressure generating chambers and piezoelectric vibrators are arranged in a staggered manner so that each piezoelectric vibrator group and the corresponding pressure generating chamber group have overlapping regions extending in the nozzle arrangement direction and the nozzle row orthogonal direction. By arranging, the head can be miniaturized.

  Furthermore, when two nozzle rows are formed using an ink jet head having pressure chambers arranged in a staggered manner or opposed to each other, it is not necessary to take a space for two heads, and it is possible to collect them in a small size. In addition, since the piezoelectric actuator does not increase in size, the rigidity of the housing that holds the flow path can be increased, and the influence of crosstalk due to the deterioration of the discharge characteristics when simultaneously driving multiple units can be reduced, so that the same function or more can be provided. Is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 9 shows an example of a droplet discharge device using the inkjet head of the present invention.

  The inkjet head 26 is a line-type inkjet head having a unit width corresponding to the printing width, and is fixed to the base. This is a fixed head printing type liquid droplet ejecting apparatus that performs printing by transporting the print medium 28 while ejecting ink onto the print area. The ink-jet head 26 is equipped with an ink cartridge 27 that supplies ink to the ink-jet head 26, and the ink-jet head 26 rests on the printing area during printing. On the other hand, the print medium 28 faces the inkjet head 26 and is conveyed by the conveyance roll 29 in the recording unit nozzle row orthogonal direction. Ink is ejected onto the print medium 28 from the nozzles of the inkjet head 26 in accordance with the recording signal, thereby forming an image.

  FIG. 1 is a perspective view of the main part of the inkjet head 26 of the present invention. FIG. 2 is a plan view of each component when the respective members in FIG. 1 are viewed from the nozzle direction. 3 to 5 are perspective views of the piezoelectric vibrator, the pressure generation chamber, and the piezoelectric vibrator as seen from the nozzle direction.

  1 to 5, reference numeral 2 denotes an orifice plate in which a plurality of nozzles 1 are formed in a row. The orifice plates 2 are arranged in a zigzag pattern for each nozzle group so as to correspond to each piezoelectric vibrator group of the piezoelectric actuator 15 described later. The processing accuracy of the opening shape of the nozzle 1 greatly affects the ink discharge characteristics of the inkjet head 26. In order to keep these nozzle accuracy variations low among the plurality of nozzles 1, the manufacturing method of the orifice plate 2 requires high processing accuracy. For this reason, the orifice plate 2 is formed by a precision press method of stainless steel, a laser processing method, nickel electroforming, or the like.

  Reference numeral 4 denotes a chamber plate in which the pressure generating chamber 3 is formed. The chamber plates 4 are arranged in a zigzag pattern around the nozzle rows so that the pressure generating chambers 3 correspond to the nozzles 1 and arranged at high density, and further generate pressure so as to correspond to each nozzle row group. The chamber group 20 is similarly arranged in a staggered manner. At this time, the pressure generation chamber groups 20 arranged in a staggered manner are arranged so that the pressure generation chamber groups 20 overlap in the nozzle orthogonal direction.

  A restrictor plate 6 connects the common ink supply path 10 and the pressure generating chamber 3 to form a restrictor 5 that controls ink inflow into the pressure generating chamber 3. The restrictors 5 are also arranged in a staggered manner around the nozzle row so as to correspond to the pressure generating chambers 3, and the restrictor groups 21 are also arranged in a staggered manner so as to correspond to each pressure generating chamber group 20. At this time, the restrictor groups 21 arranged in a staggered manner are arranged so that the restrictor groups 21 overlap in the nozzle orthogonal direction.

  Reference numeral 9 denotes elasticity that forms a diaphragm 7 for efficiently transmitting the displacement of the piezoelectric actuator 15 to the pressure generating chamber 3 and a filter portion 8 that removes dust and the like in the ink flowing into the restrictor 5 from the common ink passage 10. It has a diaphragm plate.

  Reference numeral 11 denotes a manifold plate in which a common ink passage 10 is formed. The common ink passages 10 formed in the manifold plate 11 communicate with the restrictors 5 arranged in a staggered manner so that the second row side has a convex shape as opposed to the first side concave shape as shown in the figure. is doing.

The chamber plate 4, the restrictor plate 6, the diaphragm plate 9, and the manifold plate 11 are made by a stainless steel etching method, a nickel material electroforming method, or a precision press method.
Reference numeral 13 denotes a housing in which a common ink passage 12 is formed. The housing 13 is formed by cutting stainless steel or the like, and an ink introduction pipe 14 that guides ink from an ink tank (not shown) to the common ink passages 10 and 11 is joined. The housing 13 shown in the figure has a large opening for inserting a piezoelectric actuator 15 to be described later. However, it is possible to increase the rigidity of the head 26 by opening each piezoelectric vibrator so as to have a partition.

  The pressure generating chambers 3 and the restrictor 5 are arranged in a zigzag manner with the nozzle row in the center, and a nozzle group 19, a pressure generating chamber group 20, corresponding to each bulk piezoelectric element before dicing, which will be described later, The restrictor group 21 and the diaphragm group 22 are arranged in a staggered manner and correspond to a piezoelectric vibrator group 23 described later.

  A piezoelectric actuator 15 includes a piezoelectric vibrator 17 and a fixing member 18. One end of the piezoelectric vibrator 17 is fixed to one end face of the fixing member using an adhesive, and the other end face of the piezoelectric vibrator 17 is joined to the diaphragm 7. The piezoelectric vibrators 17 are arranged on the fixing member 18 in a staggered manner with respect to the nozzle rows, and the piezoelectric vibrator groups 23 corresponding to the bulk piezoelectric elements before dicing are arranged in a staggered manner. An electric signal is input to the individual electrode pattern and the common electrode pattern of the piezoelectric actuator 15 via an FPC (not shown), causing the piezoelectric vibrator 17 to be displaced. An ink droplet is ejected by changing the pressure in the pressure generating chamber through the vibration plate 7 by the displacement generated by the piezoelectric vibrator 17 in this manner, thereby forming an image.

  As described above, the pressure generating chamber 3, the restrictor 5 and the piezoelectric vibrator 17 are arranged in a two-row staggered arrangement, and the pressure generating chamber group 20, the restrictor group 21 and the piezoelectric vibrator group 23 are overlapped. By staggering so as to have a region and forming two nozzle rows, the head unit size can be made smaller than when two head units 26 arranged in a staggered manner around the nozzle rows are arranged as shown in FIG. Can do.

  Although the pressure generating chamber 3, the restrictor 5 and the piezoelectric vibrator 17 arranged in a staggered manner in the present invention have been described, the pressure generating chamber 3, the restrictor 5 and the piezoelectric vibrator 17 arranged in an opposing manner as shown in FIG. The present invention can also be applied to a method in which the generation chamber group 20, the restrictor group 21, and the piezoelectric vibrator group 23 are arranged in a staggered manner.

  An example of a method for manufacturing the piezoelectric actuator 15 of the ink jet head of the present invention will be described with reference to FIGS. First, as shown in FIG. 6, the bulk piezoelectric elements 16 are staggered in the nozzle arrangement direction on the fixing member 18 on which the individual electrode pattern 18a and the common electrode pattern 18b are patterned. The bulk piezoelectric element 16 uses a piezoelectric element 16 having a central portion as an inactive region 16a and both ends thereof as an active region 16b. At this time, the first bulk piezoelectric element 16 in one of the rows arranged in a staggered manner overlaps with the opposing second bulk piezoelectric element 16 on the extension line in the nozzle row direction and the nozzle row orthogonal direction. The relief notches 16c are formed so as to form an array having

  In the case of FIG. 6, the individual electrode side pattern 18 a forms a groove on the opposing piezoelectric element side with a pitch twice or less of the vibrator (nozzle) pitch. Further, the two bulk-shaped piezoelectric elements 16 arranged in a staggered manner are arranged so as to have regions that overlap on the nozzle row direction extension line in the direction orthogonal to the nozzle row in the direction perpendicular to the nozzle row by the width of the piezoelectric vibrator. By configuring as described above, it is not necessary to set the positioning accuracy of the piezoelectric elements 16 to ½ of the pitch, and the piezoelectric elements 16 can be arranged up to twice the nozzle pitch as a margin.

  In FIG. 7, the piezoelectric elements 16 arranged in a staggered manner as shown in FIG. 6 are divided into two rows by the inactive region 16a. A conductive adhesive 25 is applied to the divided intermediate region, and the individual electrode and the common electrode of the external electrode of the piezoelectric element 16 are conducted to the individual electrode pattern 18 a and the common electrode pattern 18 b applied to the fixing member 18. Since the piezoelectric element 16 as described above is used, the positioning accuracy of the bulk piezoelectric element facing the center of the nozzle row can be relaxed, and the effect of suppressing the positioning accuracy can be enhanced.

  Finally, as shown in FIG. 8, the piezoelectric element 16 bonded and fixed is divided into a comb shape by a wire saw or a dicing process so as to be equal to the pitch of the pressure generating chambers 3 and the staggered arrangement position. The piezoelectric actuator 15 having the vibrator 17 is obtained.

  Regarding the manufacturing method of the piezoelectric actuator 15, the piezoelectric vibrator group 23, the piezoelectric vibrator 17 in the pressure generation chamber group, and the pressure generation chamber may be arranged to face each other in the nozzle array center. The opposing arrangement causes a problem of complication of the electrode pattern formed on the ceramic plate, but there is an advantage that the processing time when the piezoelectric vibrator 17 is formed by dicing can be shortened.

  By adopting the structure of the piezoelectric actuator 15 of the present invention, it is possible to form a piezoelectric actuator that does not require positioning accuracy and can suppress the dimension between the piezoelectric vibrations in the nozzle row orthogonal direction. The dimension width in the direction perpendicular to the nozzle row can reduce the opening of the housing of the piezoelectric vibrator 17 into which the piezoelectric actuator 15 is inserted, and can improve the flow path knuckle 24 characteristics. Further, it is caused by deformation of the flow path cum 24 when a plurality of piezoelectric vibrators 17 are driven simultaneously. It is possible to reduce the so-called crosstalk of the discharge characteristics.

1 is a perspective view of an inkjet head according to the present invention. It is a top view of each component seen from the nozzle side of the inkjet head in the present invention. 4 is a perspective view of a piezoelectric vibrator, a pressure generation chamber, and a piezoelectric vibrator from the nozzle side in the inkjet head of the present invention. FIG. FIG. 5 is a perspective view seen from the nozzle side when two rows of nozzles are arranged in a head in which piezoelectric vibrators and pressure generation chambers are arranged in a staggered manner with the nozzle row as a center. FIG. 3 is a perspective view seen from the nozzle side of a head in which a piezoelectric vibrator group and a pressure generation chamber group according to the present invention are arranged in a staggered manner. The manufacturing method of the piezoelectric actuator by this invention is shown, (a) is a front view, (b) is a top view, (c) is a side view. The manufacturing method of the piezoelectric actuator by this invention is shown, (a) is a front view, (b) is a top view, (c) is a side view. The manufacturing method of the piezoelectric actuator by this invention is shown, (a) is a front view, (b) is a top view, (c) is a side view. It is the schematic of the droplet discharge apparatus using the head unit using this invention.

Explanation of symbols

1: nozzle, 2: orifice plate, 3: pressure generation chamber, 4: chamber plate, 5: restrictor, 6: restrictor plate, 7: diaphragm, 8: filter section, 9: diaphragm plate, 10: common ink Passage (manifold), 11: manifold plate, 12: common ink passage (housing), 13: housing, 13a: opening, 14: ink introduction pipe, 15: piezoelectric actuator, 16: bulk piezoelectric element, piezoelectric element, 16a : Active region, 16b: Inactive region, 17: Piezoelectric vibrator, 18: Fixing member, 18a: Individual electrode side pattern 18b: Common electrode side pattern, 19: Nozzle row group, 20: Pressure generating chamber group, 21: List Rector group, 22: Diaphragm group, 23: Piezoelectric vibrator group, 24: Channel kumi, 25: Conductive adhesive, 26: In Jet head, a head unit, 27: ink cartridge, 28: print media, 29: transport roll.

Claims (5)

  An orifice plate having a plurality of nozzles for discharging ink droplets; a chamber plate having a pressure generating chamber communicating with the nozzle; a diaphragm plate for sealing the pressure generating chamber; and the pressure generating chamber via the diaphragm plate. In an inkjet head having a plurality of piezoelectric actuators composed of a plurality of piezoelectric vibrators for changing the volume, the pressure in at least one pressure generating chamber group of the chamber plate and in the at least one piezoelectric vibrator group of the piezoelectric actuator The generating chambers and the piezoelectric vibrators are arranged in a zigzag shape or opposed to each other centering on the nozzle row or the middle of the nozzle rows, and the plurality of pressure generating chamber groups and the piezoelectric vibrator groups are staggered on at least one fixing member. An inkjet head characterized by being held.   2. The ink jet head according to claim 1, wherein the piezoelectric vibrator rows are constituted by at least three rows and the nozzle rows are constituted by at least two rows.   2. An ink jet head according to claim 1, wherein said one piezoelectric vibrator group includes one bulk piezoelectric element divided into a plurality of piezoelectric vibrators.   Both end portions of the piezoelectric element forming the piezoelectric vibrator have an orifice plate having a plurality of nozzles for discharging ink droplets overlapping in the nozzle row direction and the nozzle row orthogonal direction, and pressure generation in communication with the nozzles An inkjet head having a chamber plate having a chamber, a diaphragm plate for sealing the pressure generation chamber, and a plurality of piezoelectric actuators including a plurality of piezoelectric vibrators that change the volume of the pressure generation chamber via the diaphragm plate In the at least one pressure generating chamber group of the chamber plate, the pressure generating chambers in the at least one piezoelectric vibrator group of the piezoelectric actuator, and the piezoelectric vibrators staggered from each other around the nozzle row or the middle of the nozzle row Alternatively, the plurality of pressure generation chamber groups and the piezoelectric vibrator groups are few in an opposed manner. Ink jet head according to claim 1, characterized in that it has a frequency which is characterized in that it is held in a zigzag pattern in the one fixing member both. A droplet discharge device comprising the inkjet head according to claim 1.

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