JP2009051061A - Inkjet type recording head unit, its manufacture method, and inkjet type recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet type recording head unit capable of inexpensively achieving high-speed and high-quality printing, and its manufacture method and an inkjet type recording device. <P>SOLUTION: The inkjet type recording head unit 1 provided with a plurality of nozzle trains 21A where nozzle apertures 21 ejecting ink are juxtaposed includes a pair of nozzle trains 21A ejecting the same color ink, wherein the pair of nozzle trains 21A having an inclination that the ink ejection amount of ink drops ejected from the nozzle apertures 21 based on the same driving signal becomes gradually smaller from one end side to the other end side of the nozzle train 21A is arranged so that the inclination that the ink ejection amount of the nozzle train 21A becomes gradually smaller may be reverse to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording head unit that performs printing by ejecting ink of different colors from a plurality of nozzle arrays in which nozzle openings for ejecting ink are arranged in parallel, and a method for manufacturing the same, and an ink jet recording apparatus.

  An ink jet recording head unit (hereinafter also referred to as a head unit) having an ink jet recording head for ejecting ink includes an ink jet recording head having an ink ejection surface in which a nozzle opening for ejecting ink is opened, and ink jet recording. Some have a holding member such as a fixed plate that is bonded to the ink ejection surface of the head via an adhesive (see, for example, Patent Document 1).

  In addition, a correction circuit for adjusting the pressure fluctuation characteristic of the pressure generation chamber is provided in the ink jet recording head, and the correction circuit prevents a variation in the pressure fluctuation characteristic of the pressure generation chamber and improves the print quality. (For example, refer to Patent Document 2).

Japanese Patent Laying-Open No. 2005-096419 (pages 7 to 12, FIGS. 1 to 3) JP 2000-351209 A (pages 6 to 10, FIGS. 1 to 3)

  However, the ink jet recording head has variations in the displacement characteristics of the pressure generating means such as piezoelectric elements and the volume of the pressure generating chamber due to variations in film formation during manufacturing and variations in the pressure generating chamber. There is a problem that the ink discharge amount of the ink droplets discharged from the nozzle openings in the nozzle row tends to gradually decrease from the one end side to the other end side of the nozzle row.

  In the ink jet recording head unit in which a plurality of ink jet recording heads are arranged so as to gradually decrease the ink discharge amount of the nozzle row, for example, printing is performed by moving the ink jet recording head unit in the main scanning direction. After performing pass printing, if the recording paper is moved in the sub-scanning direction to perform one-pass printing, so-called microfeed or bind printing, the color density changes abruptly between passes, resulting in print quality. There is a problem that will deteriorate.

  In addition, as disclosed in Patent Document 2, it is possible to prevent variations in ink ejection characteristics by providing a correction circuit. However, there is a problem in that the correction circuit is necessary and the number of parts increases, resulting in an increase in cost.

  In view of such circumstances, an object of the present invention is to provide an ink jet recording head unit that can perform high-speed and high-quality printing at low cost, a manufacturing method thereof, and an ink jet recording apparatus.

An aspect of the present invention that solves the above problems is an ink jet recording head unit provided with a plurality of nozzle arrays in which nozzle openings for discharging ink are arranged in parallel.
Comprising a pair of nozzle rows from which ink of the same color is ejected;
A nozzle row in which the ink discharge amount of ink droplets discharged from the nozzle openings based on the same drive signal tends to gradually decrease from one end side to the other end side of the nozzle row is the ink of the nozzle row The ink jet recording head unit is characterized in that the pair of nozzle rows are arranged such that the tendency of the discharge amount to gradually decrease is reversed.
In this aspect, for example, when different colors are superimposed and various colors are printed in one pass, the color density can be averaged or density unevenness can be made inconspicuous in the direction in which the nozzle openings of the nozzle row are arranged. Moreover, since density unevenness between passes can be prevented or made inconspicuous when microfeed printing or bind printing is performed, high-speed and high-quality printing can be performed. In addition, density unevenness can be prevented or made inconspicuous only by the arrangement of the ink jet recording head, so that a correction circuit for correcting the drive waveform is not required, and high-quality printing can be performed at low cost at high speed. it can.

  Here, a pair of nozzle rows from which ink of the same color is ejected is displaced in the direction of the nozzle row by a half pitch of the pitch of the nozzle openings arranged in parallel in one nozzle row. A nozzle opening is preferably provided. According to this, the ink discharge amount at the time of one pass printing can be averaged to prevent density unevenness, and density unevenness between passes at the time of microfeed printing or bind printing can be prevented.

  In addition, a pair of nozzle rows from which the same color ink is ejected has a nozzle opening at one end of one nozzle row and a nozzle opening at the other end of the other nozzle row at the same position in the parallel arrangement direction of the nozzle openings. It is preferable to arrange so as to be. According to this, density unevenness can be made inconspicuous at the boundary between a pair of nozzle rows during one-pass printing, and density unevenness between passes during microfeed printing or bind printing can be made inconspicuous.

  The ink jet recording head includes a flow path forming substrate provided with a pressure generating chamber communicating with the nozzle opening, and a lower electrode provided in a region facing the pressure generating chamber of the flow path forming substrate, It is preferable to include a piezoelectric element including a piezoelectric layer and an upper electrode. According to this, high-speed and high-quality printing is possible even when using an ink jet recording head in which the ink discharge amount of the nozzle array tends to vary due to variations due to characteristics of the piezoelectric elements or variations in the formation of the pressure generation chamber. Can be performed.

  Furthermore, another aspect of the present invention is an ink jet recording apparatus comprising the ink jet recording head unit of the above aspect. In this aspect, an ink jet recording apparatus that can perform high-speed and high-quality printing at low cost can be realized.

Furthermore, another aspect of the present invention includes an inkjet recording head including a plurality of inkjet recording heads including nozzle arrays in which nozzle openings for ejecting ink are arranged in parallel, and an inkjet including a pair of nozzle arrays from which the same color ink is ejected. A method for manufacturing an ink jet recording head unit, wherein when the ink jet recording head is manufactured, an ink discharge amount of ink droplets discharged from the nozzle openings based on the same drive signal is determined from one end side of the nozzle row. When the ink jet recording head having a tendency to gradually decrease toward the other end portion is formed, the ink jet recording head is configured to gradually decrease the ink discharge amount of the nozzle array in the pair of nozzle arrays. An inkjet recording head unit manufacturing method is characterized in that the arrangement is such that the trends are reversed.
In such an aspect, even when the ink discharge amount of the nozzle row tends to vary during the manufacture of the ink jet recording head, for example, when different colors are superimposed and various colors are printed in one pass, the color density of the nozzle row is changed. Averaging or density unevenness can be made inconspicuous in the direction in which the nozzle openings are arranged side by side. Moreover, since density unevenness between passes can be prevented or made inconspicuous when microfeed printing or bind printing is performed, high-speed and high-quality printing can be performed. In addition, density unevenness can be prevented or made inconspicuous only by the arrangement of the ink jet recording head, so that a correction circuit for correcting the drive waveform is not required, and high-quality printing can be performed at low cost at high speed. it can.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a schematic diagram illustrating an example of an ink jet recording apparatus. As shown in FIG. 1, the ink jet recording apparatus I includes two ink jet recording head units 1 (hereinafter also referred to as head units 1) each having an ink jet recording head. The two head units 1 are detachably provided with a plurality of cartridges 1 </ b> A constituting ink supply means, and are mounted on a carriage 3. A carriage 3 on which the head unit 1 is mounted is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. As will be described later in detail, each ink jet recording head of each head unit 1 discharges four color inks in this embodiment, and four ink cartridges 1A respectively storing four color inks are provided. It is provided in the head unit 1.

  Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the head unit 1 is mounted is moved along the carriage shaft 5. On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  Here, each head unit 1 will be described in detail. FIG. 2 is an exploded perspective view showing a schematic configuration of the head unit.

  As shown in FIG. 2, the cartridge case 210 of the head unit 1 has cartridge mounting portions 211 to which ink cartridges 1 </ b> A as ink supply means are respectively mounted. The bottom surface of the cartridge case 210 is provided with a plurality of ink communication paths (not shown) having one end opened to each cartridge mounting portion 211 and the other end opened to the head case side described later. Further, an ink supply needle 213 to be inserted into the ink supply port of the ink cartridge is formed in the ink communication path in the ink communication path of the cartridge mounting portion 211 in order to remove bubbles and foreign matters in the ink. It is fixed via a filter (not shown).

  A plurality of ink jet recording heads 2 that eject ink are fixed to the bottom surface side of the cartridge case 210. As will be described in detail later, the ink jet recording head 2 is provided with a nozzle row in which nozzle openings are arranged in parallel. From the nozzle row of each ink jet recording head 2, black (K), cyan (C ), Magenta (M), and yellow (Y) ink are ejected. In other words, in the present embodiment, one head unit 1 is provided with four ink jet recording heads 2 each provided with a nozzle array for ejecting four colors of ink. As described above, the carriage 3 of the ink jet recording apparatus I is provided with the two head units 1. As will be described in detail later, four color inks are ejected from each head unit 1.

  Further, a cover head 240 that protects the ink ejection surface side of the plurality of ink jet recording heads 2 is provided on the ink ejection surface side where the nozzle openings of the ink jet recording head 2 are opened. The ink discharge surface of the ink jet recording head 2 is a surface where nozzle openings for discharging ink are opened, as will be described in detail later. The cover head 240 is a surface of the ink discharge surface of each ink jet recording head 2. Exposed openings 241 that respectively open the nozzle rows 21A are provided.

  Specifically, the cover head 240 includes an exposed opening 241 that exposes the nozzle opening 21, and a joint 242 that defines the exposed opening 241 and is joined to the ink ejection surface A of the ink jet recording head 2. It has.

  In the present embodiment, the joint portion 242 extends between the fixing frame portion 243 provided along the outer periphery of the ink ejection surface A across the plurality of ink jet recording heads 2 and the adjacent ink jet recording head 2. And a fixing beam portion 244 that is provided and divides the exposed opening 241. A joint portion 242 including the fixing frame portion 243 and the fixing beam portion 244 is simultaneously joined to the ink discharge surfaces A of the plurality of ink jet recording heads 2.

  Here, an example of the ink jet recording head 2 will be described. FIG. 3 is a plan view of the ink jet recording head and a sectional view taken along line AA ′.

  As shown in the drawing, the flow path forming substrate 10 constituting the ink jet recording head 2 is made of a silicon single crystal substrate having a plane orientation (110) in this embodiment, and one surface thereof is made of silicon dioxide with a thickness of 0. An elastic film 50 having a thickness of 5 to 2 μm is formed.

  In the flow path forming substrate 10, pressure generating chambers 12 partitioned by a plurality of partition walls 11 are arranged in parallel in the width direction (short direction) by anisotropic etching from the other surface side. Further, an ink supply path 14 and a communication path 15 are partitioned by a partition wall on one end side in the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10. Further, at one end of the communication passage 15, a communication portion 13 that forms a part of the reservoir 100 that is a common ink chamber of each pressure generation chamber 12 is formed. That is, the flow path forming substrate 10 is provided with an ink flow path including a pressure generation chamber 12, a communication portion 13, an ink supply path 14, and a communication path 15. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13.

  Further, on the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is provided with an adhesive. Or a heat-welded film or the like. The nozzle opening 21 of the nozzle plate 20 is formed at a position communicating with the pressure generation chamber 12 on the side opposite to the ink supply path 14. In the present embodiment, since one row in which the pressure generation chambers 12 are arranged in parallel is provided on the flow path forming substrate 10, one nozzle row 21A in which nozzle openings 21 are arranged in parallel is provided in one ink jet recording head 2. (See FIG. 8). In the present embodiment, the surface of the nozzle plate 20 where the nozzle openings 21 are opened is the ink discharge surface A. Examples of such a nozzle plate 20 include a silicon single crystal substrate and a metal substrate such as stainless steel (SUS).

  Further, in the ink jet recording head 2 of the present embodiment, the direction in which the nozzle openings 21 are juxtaposed with each other intersects the main scanning direction (movement direction of the carriage 3) of the head unit 1, that is, the sub-scanning direction (recording sheet). It is mounted on the head unit 1 so as to be in the (S transport direction). That is, in the plurality of ink jet recording heads 2, the nozzle rows 21 </ b> A are arranged in parallel in the main scanning direction of the head unit 1.

  Further, each of the inkjet recording heads 2 is provided with a nozzle plate 20. The nozzle plate 20 has a slightly larger area than the exposed opening 241 of the cover head 240 and overlaps the cover head 240. It is fixed with an adhesive.

  On the other hand, as described above, the elastic film 50 having a thickness of, for example, about 1.0 μm is formed on the side opposite to the opening surface of the flow path forming substrate 10. For example, an insulator film 55 having a thickness of about 0.4 μm is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.1 μm, and a thickness of, for example, about 0 The upper electrode film 80 having a thickness of 0.05 μm is laminated by a process described later to constitute the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In this case, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In this embodiment, as will be described in detail later, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300, and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. There is no problem. In addition, here, the piezoelectric element 300 and the diaphragm that is displaced by driving the piezoelectric element 300 are collectively referred to as an actuator device. In the above-described example, the elastic film 50, the insulator film 55, and the lower electrode film 60 function as a diaphragm. However, the present invention is not limited to this, and for example, the elastic film 50 and the insulator film 55 are provided. Instead, only the lower electrode film 60 may act as a diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

  The piezoelectric layer 70 is a crystal film having a perovskite structure formed on the lower electrode film 60. As the piezoelectric layer 70, for example, a ferroelectric material such as lead zirconate titanate (PZT) or a material obtained by adding a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide to the ferroelectric material is suitable. The piezoelectric layer 70 is formed thick enough to suppress the thickness so as not to generate cracks in the manufacturing process and to exhibit sufficient displacement characteristics. For example, in this embodiment, the piezoelectric layer 70 is formed with a thickness of about 1 to 2 μm.

  Further, each upper electrode film 80 that is an individual electrode of the piezoelectric element 300 is provided with a lead electrode 90 made of, for example, gold (Au) or the like as a lead-out wiring drawn out from the vicinity of the end on the ink supply path 14 side. ing. The lead electrode 90 is electrically connected to the drive circuit 120 via the connection wiring 121 through a through hole 33 described later in detail.

  Further, on the flow path forming substrate 10 on which the piezoelectric element 300 is formed, a protective substrate 30 provided with a reservoir portion 31 in a region facing the communication portion 13 is bonded via an adhesive 35. As described above, the reservoir unit 31 communicates with the communication unit 13 of the flow path forming substrate 10 and constitutes the reservoir 100 serving as a common ink chamber for the pressure generation chambers 12. Alternatively, the communication portion 13 of the flow path forming substrate 10 may be divided into a plurality of pressure generation chambers 12 and only the reservoir portion 31 may be used as the reservoir. Further, for example, only the pressure generation chamber 12 is provided in the flow path forming substrate 10, and a reservoir and a member interposed between the flow path forming substrate 10 and the protective substrate 30 (for example, the elastic film 50, the insulator film 55, etc.) An ink supply path 14 that communicates with each pressure generating chamber 12 may be provided.

  A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The piezoelectric element holding part 32 only needs to have a space that does not hinder the movement of the piezoelectric element 300, and the space may be sealed or unsealed.

  As such a protective substrate 30, it is preferable to use substantially the same material as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10 is used. The silicon single crystal substrate was used.

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end of the lead electrode 90 (connection layer 301) drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  A drive circuit 120 for driving the piezoelectric elements 300 arranged in parallel is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire. Note that the connection wiring 121 is electrically connected to the lead electrode 90 on the connection layer 301 as described above. The connection between the connection wiring 121 and the lead electrode 90 includes, for example, wire bonding.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and the sealing film 41 seals one surface of the reservoir portion 31. It has been stopped. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  In the ink jet recording head 2 of this embodiment, ink is taken in from the ink introduction port connected to the ink cartridge shown in FIG. 2 via the ink communication path of the cartridge case 210 and reaches from the reservoir 100 to the nozzle opening 21. After the inside is filled with ink, a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12 in accordance with a recording signal from the drive circuit 120, and the elastic film 50 is insulated. By flexing and deforming the body film 55, the lower electrode film 60, and the piezoelectric layer 70, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle openings 21.

Hereinafter, a method for manufacturing such an ink jet recording head 2 will be described with reference to FIGS. 4 to 7 are cross-sectional views in the longitudinal direction of the pressure generating chamber showing the method of manufacturing the ink jet recording head according to the first embodiment of the present invention. First, as shown in FIG. 4A, a silicon dioxide film 51 made of silicon dioxide (SiO ₂ ) constituting the elastic film 50 is formed on the surface of a flow path forming substrate wafer 110 that is a silicon wafer. Next, as shown in FIG. 4B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51).

  Next, as shown in FIG. 4C, a lower electrode film 60 made of platinum (Pt) and iridium (Ir) is formed over the entire surface of the insulator film 55 of the flow path forming substrate wafer 110. At the same time, it is patterned into a predetermined shape.

  Next, as shown in FIG. 5A, for example, a piezoelectric layer 70 made of lead zirconate titanate (PZT) or the like and an upper electrode film 80 made of iridium, for example, are formed on the wafer 110 for flow path forming substrate. Then, as shown in FIG. 5B, patterning is performed in a region facing each pressure generating chamber 12 to form a piezoelectric element 300. As a material of the piezoelectric layer 70 constituting the piezoelectric element 300, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) or a metal such as niobium, nickel, magnesium, bismuth or yttrium is used. An added relaxor ferroelectric or the like is used. In the present embodiment, the piezoelectric layer 70 is formed by applying a so-called sol in which a metal organic material is dissolved and dispersed in a solvent, drying it to gel, and baking it at a high temperature to form a piezoelectric layer made of a metal oxide. The piezoelectric layer 70 was formed using a so-called sol-gel method for obtaining 70. The method for forming the piezoelectric layer 70 is not particularly limited, and for example, a MOD method or a sputtering method may be used.

  Next, as shown in FIG. 5C, a lead electrode 90 made of gold (Au) is formed over the entire surface of the flow path forming substrate wafer 110, and then patterned for each piezoelectric element 300.

  Next, as illustrated in FIG. 6A, the protective substrate wafer 130 is bonded to the flow path forming substrate wafer 110 via the adhesive 35. Here, the protective substrate wafer 130 is formed by integrally forming a plurality of protective substrates 30, and a reservoir portion 31 and a piezoelectric element holding portion 32 are formed in advance on the protective substrate wafer 130.

  Next, as shown in FIG. 6B, the flow path forming substrate wafer 110 is thinned to a predetermined thickness. Next, as shown in FIG. 6C, a mask film 52 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, as shown in FIG. 7, the pressure corresponding to the piezoelectric element 300 is obtained by performing anisotropic etching (wet etching) using an alkaline solution such as KOH on the flow path forming substrate wafer 110 through the mask film 52. A generation chamber 12, a communication portion 13, an ink supply path 14, a communication path 15 and the like are formed.

  Then, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by cutting, for example, by dicing. The nozzle plate 20 having the nozzle openings 21 formed on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130 is bonded, and the compliance substrate 40 is bonded to the protective substrate wafer 130. Then, the flow path forming substrate wafer 110 and the like are divided into a single chip size flow path forming substrate 10 as shown in FIG.

  The ink jet recording head 2 manufactured by such a process has an ink discharge amount of ink droplets discharged from the nozzle openings 21 based on the same drive signal in one nozzle row 21A (see FIG. 8). There is a case where the ink jet recording head 2 having a tendency to gradually decrease from the nozzle opening 21 provided on one end side of the nozzle row 21A toward the nozzle opening 21 provided on the other end side may be manufactured. This is because, for example, when the inkjet recording head 2 is manufactured by the above-described manufacturing method, the thickness of the piezoelectric element 300 during film formation, the firing temperature, or the like, or when the flow path forming substrate 10 is anisotropically etched. This occurs due to variations in the amount of etching. Note that the tendency of variation in the ink discharge amount in the nozzle row 21A is also caused by other factors such as variation in the opening area of the nozzle openings 21, and is not limited to these manufacturing methods.

  Thus, in one nozzle row 21A, the ink jet recording head 2 having a tendency to gradually reduce the amount of ink discharged from the nozzle openings 21 is a pair of nozzle rows 21A that discharge ink that is used frequently. The nozzle arrays 21A are arranged so that the decreasing tendency of the ink discharge amount of the nozzle row 21A is reversed.

  Note that the amount of ink discharged from each nozzle opening 21 of the ink jet recording head 2 is determined by measuring the capacitance of the piezoelectric element 300 (piezoelectric layer 70) corresponding to the nozzle opening 21, for example. By grasping the displacement amount, the ink discharge amount corresponding to the piezoelectric element 300 can be grasped. Further, the ink discharge amount can also be grasped by measuring the resonance frequency of the pressure generating chamber 12. Such a tendency of the ink discharge amount in the nozzle row 21A can be grasped by measuring the piezoelectric elements 300 corresponding to the nozzle openings 21 at a ratio of one to a plurality.

  Thus, by measuring the ink discharge amount of the ink jet recording head 2, the tendency of the ink discharge amount of the ink jet recording head 2 is acquired, and the ink jet recording head 2 is classified based on the tendency of the ink discharge amount. Incidentally, the classification based on the tendency of the ink discharge amount of the ink jet recording head 2 is performed by attaching the ink jet recording head 2 to the cartridge case 210 or the like when the head unit 1 is manufactured by combining a plurality of ink jet recording heads 2. Since the direction (the direction of the nozzle row 21A) is defined by its shape, the direction is determined based on the shape of the ink jet recording head 2 itself and the tendency of the ink discharge amount. Note that when the head unit 1 is manufactured, the ink jet recording head 2 is arranged so that the tendency of the ink discharge amount is arranged in detail later. For this reason, the manufacturing process of the head unit 1 can be simplified by classifying the ink jet recording head 2 in advance based on the tendency of the ink discharge amount.

  Here, the arrangement of the plurality of ink jet recording heads 2 in the ink jet recording head unit 2 of the present embodiment will be described in detail. FIG. 8 is a plan view showing the arrangement of the ink jet recording head of the head unit.

  As shown in FIG. 8, in this embodiment, one head unit 1 is provided with four ink jet recording heads 2A to 2D and 2E to 2H. In the present embodiment, different colors, that is, black (K), cyan (C), magenta (from the nozzle rows 21A of the ink jet recording heads 2A to 2D of one head unit 1 of the two head units 1, respectively. M) and yellow (Y) are discharged. Similarly, different colors are discharged from the nozzle rows 21A of the ink jet recording heads 2E to 2H of the other head unit of the two head units 1, respectively. That is, the two head units 1 are provided with two nozzle rows 21A for ejecting ink of each color.

  Further, the two head units 1 have a half pitch of the pitch of the nozzle openings 21 arranged in parallel in a direction in which a pair of nozzle rows 21A from which ink of the same color is ejected intersects the parallel direction of the nozzle rows 21A. It is provided so as to be a position shifted by a minute. That is, the two head units 1 are arranged such that each nozzle row 21A is shifted by a half pitch of the nozzle openings 21 in the sub-scanning direction. With such an arrangement, printing can be performed with a resolution that is twice the pitch of the nozzle openings 21 arranged in parallel in one nozzle row 21A. The pair of nozzle rows 21 </ b> A may be arranged such that the other nozzle row 21 </ b> A is shifted by 1.5 pitches of the nozzle openings 21 with respect to the one nozzle row 21 </ b> A.

  The pair of nozzle rows 21A of the ink jet recording heads 2A to 2D and 2E to 2H that discharge the same color are arranged so that the tendency of the ink discharge amount of the nozzle rows 21A is reversed.

  That is, the pair of nozzle rows 21A of the ink jet recording heads 2A and 2E that discharge black ink are arranged so that the tendency of the ink discharge amount is reversed. Similarly, a pair of nozzle rows 21A for ink jet recording heads 2B and 2F that discharge cyan ink, a pair of nozzle rows 21A for ink jet recording heads 2C and 2G that discharge magenta ink, and an ink jet recording head that discharges yellow ink. A pair of 2D and 2H nozzle rows 21A is also arranged so that the tendency of the ink ejection amount is reversed.

  In the present embodiment, the ink jet recording heads 2A to 2D of one head unit 1 are arranged so that the ink discharge amount of the nozzle row 21A gradually decreases toward the lower side in FIG. The ink jet recording heads 2E to 2H of the other head unit 1 are arranged so that the ink discharge amount of the nozzle array 21A gradually decreases toward the upper side in FIG. 8 opposite to the ink jet recording heads 2A to 2D. ing.

  In this way, by arranging the pair of nozzle rows 21A that discharge ink of the same color so that the tendency of the ink discharge amount of the nozzle row 21A is reversed with each other, by using these inks to overlap each other, When the colors are printed, the color density can be averaged in the direction in which the nozzle openings 21 of the nozzle row 21A are arranged in parallel.

  That is, for example, on the upper side in FIG. 8, the amount of ink ejected from the ink jet recording head 2B of one head unit 1 that ejects cyan ink is relatively large, and the ink jet recording head 2F of the other head unit 1 is relatively high. The amount of ink discharged from the ink is relatively small. Conversely, on the lower side in FIG. 8, the amount of ink discharged from the ink jet recording head 2B of one head unit 2 that discharges cyan ink is relatively small, and the ink jet recording of the other head unit 1 is performed. The amount of ink discharged from the head 2F is relatively large. Therefore, when one-pass printing is performed in which printing is performed by ejecting ink while moving the two head units 1 in the main scanning direction, as shown in FIG. 9A, the density is averaged and printed.

  Also, as shown in FIG. 9A, so-called microfeed printing or bind printing is performed in which one-pass printing is performed, then the recording sheet S is moved by one pass in the sub-scanning direction, and then further one-pass printing is performed. It is possible to prevent density unevenness from occurring between the one pass printing and the one pass printing.

  Incidentally, when a pair of nozzle rows 21A that discharge ink of the same color are arranged so that the tendency of the ink discharge amount of the nozzle rows 21A is the same, as shown in FIG. In addition, density unevenness occurs, and the density difference between the 1-pass printing and the 1-pass printing increases, and the unevenness becomes conspicuous.

  In this way, even if printing is performed in a high-speed printing direction such as microfeed printing or bind printing by arranging the pair of nozzle rows 21A that discharge ink of the same color so that the tendency of the ink discharge amount is mutually reversed, It is possible to prevent the occurrence of density unevenness in one-pass printing, and to prevent the occurrence of density unevenness between passes, thereby improving the print quality.

(Embodiment 2)
FIG. 10 is a plan view of a head unit according to the second embodiment of the present invention, and FIG. 11 is a diagram illustrating density unevenness during printing according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to Embodiment 1 mentioned above, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 10, the two head units 1 have a pair of nozzle rows 21A that discharge ink of the same color, and one end of one nozzle row 21A and the other end of the other nozzle row are sub-scanned. It arrange | positions so that it may become the same position in a direction. In other words, one head unit 1 and the other head unit 1 that is shifted from the one head unit 1 in the sub-scanning direction by the length of the nozzle row 21A are provided.

  According to such two head units 1, since the length of the two nozzle rows 21A can be simultaneously printed by one-pass printing, high-speed printing can be performed.

  Each of the ink jet recording heads 2A to 2H of each head unit 1 is provided with a pair of nozzle rows 21A that discharge ink of the same color so that the tendency of the ink discharge amount is reversed.

  In the present embodiment, as in the first embodiment described above, the ink jet recording heads 2A to 2D of one head unit 1 are configured so that the ink discharge amount of the nozzle row 21A gradually decreases toward the lower side in FIG. The ink jet recording heads 2E to 2H of the other head unit 1 are arranged so that the ink discharge amount of the nozzle row 21A gradually decreases toward the upper side in FIG. 10 opposite to the ink jet recording heads 2A to 2D. did.

  When one-pass printing is performed using such a head unit 1, for example, in the ink jet recording heads 2B and 2E having a pair of nozzle rows 21A for discharging cyan ink, in one ink jet recording head 2B, FIG. As shown in FIG. 11A, printing is performed so that the ink discharge amount gradually decreases from the upper side to the lower side in FIG. 11, and the other ink jet recording head 2F moves from the lower side to the upper side in FIG. Thus, printing is performed so that the ink discharge amount gradually decreases. Therefore, in the one-pass printing of the ink jet recording head 2B and the ink jet recording head 2E, it is possible to perform printing so that density unevenness is not noticeable between the nozzle arrays 21A of the ink jet recording heads 2B and 2E.

  Further, when microfeed printing or bind printing is performed using such a head unit 1, as shown in FIG. 11A, the density 203 between the one-pass printing and the one-pass printing is dark or thin. Since they are adjacent to each other at the same density such as densities, printing can be performed so that density unevenness is not noticeable.

  On the other hand, when the pair of nozzle rows 21A that discharge ink of the same color are arranged so that the tendency of the ink discharge amount is the same, as shown in FIG. The density difference becomes large and density unevenness becomes conspicuous in 204 during printing by the nozzle row 21A, and the density difference becomes large and density unevenness becomes noticeable in 205 between the 1-pass printing and 1-pass printing. End up.

  In this way, even if printing is performed in a high-speed printing direction such as microfeed printing or bind printing by arranging the pair of nozzle rows 21A that discharge ink of the same color so that the tendency of the ink discharge amount is mutually reversed, It is possible to make the density unevenness in one-pass printing inconspicuous and to improve the print quality by making the density unevenness between passes inconspicuous.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, in the first and second embodiments described above, an example in which four ink jet recording heads 2A to 2D and 2E to 2H for ejecting four colors of ink are provided in one head unit 1 has been described. For example, the head unit has more than four colors of ink, for example, black (K), light black (LK), light light black (LLK), cyan (C), light cyan (LC), magenta (M), Eight ink jet recording heads for ejecting eight colors of light magenta (LC) and yellow (Y) may be provided. Note that light black (LK), light cyan (LC), and light magenta (LM) are higher in brightness than black (K), cyan (C), and magenta (M), and light light black (LLK) is The lightness is higher than that of light black (LK). In the first embodiment described above, the ink jet recording heads 2A to 2D and 2E to 2H for ejecting different color inks are provided on each head unit 1, respectively. A plurality of ink jet recording heads 2 that eject ink of the same color may be provided in one head unit. Furthermore, in the first embodiment described above, the example in which the two head units 1 are provided has been described. However, the number of the head units 1 is not particularly limited thereto, and three or more head units are provided. Also good.

  In the first and second embodiments described above, a pair of nozzle arrays 21A (ink jet recording heads 2) that discharge ink of the same color is provided. However, the present invention is not particularly limited thereto, and for example, three or more nozzle arrays are provided. It may be. For example, in the case where an even number of nozzle rows 21A for ejecting the same color ink is provided, the nozzle rows 21A as a pair may be arranged so that the tendency of the ink ejection amount is mutually reversed. Of course, even when an odd number of nozzle rows 21A for ejecting the same color of ink is provided, the plurality of nozzle rows 21A having the same tendency of the ink ejection amount and the plurality of nozzle rows 21A having the tendency to be reversed are provided. Can be improved so that the print quality can be improved.

  Furthermore, in the first and second embodiments described above, in each head unit 1, the ink jet recording heads 2 </ b> A to 2 </ b> D and 2 </ b> E to 2 </ b> H are arranged so that the tendency of the ink discharge amount to become the same tendency. However, the present invention is not limited to this, and in each head unit 1, the ink discharge amount may be arranged so as to be mixed gradually in each of the ink jet recording heads 2A to 2D and 2E to 2H. In any case, it is only necessary that the pair of nozzle rows 21A that discharge ink of the same color are arranged such that the tendency of the ink discharge amount to gradually reverse.

  Further, in the first and second embodiments described above, the actuator device having the thin film type piezoelectric element 300 has been described as the pressure generating means for generating the pressure change in the pressure generating chamber 12 that is the ink flow path. For example, a thick film type actuator device formed by a method such as attaching a green sheet, or a longitudinal vibration type actuator in which piezoelectric materials and electrode forming materials are alternately stacked to expand and contract in the axial direction A device or the like can be used. Also, as a pressure generating means, a heating element is arranged in the pressure generating chamber, and droplets are discharged from the nozzle opening by bubbles generated by the heat generated by the heating element, or static electricity is generated between the diaphragm and the electrode. Thus, it is possible to use a so-called electrostatic actuator that deforms the diaphragm by electrostatic force and ejects droplets from the nozzle openings. That is, the present invention uses any pressure generating means as long as the ink jet recording head has a tendency that the ink discharge amount gradually decreases from one end side to the other end side of the nozzle row. Also good.

  Further, in the first and second embodiments described above, the ink jet recording apparatus I in which the carriage 3 holding the head unit 2 moves in the main scanning direction is illustrated, but the invention is not particularly limited thereto. A head unit used in a so-called line-type ink jet recording apparatus in which a plurality of head units 1 are arranged in the main scanning direction without being moved, and the recording sheet S is moved in the sub scanning direction for printing. Also, the present invention can be applied.

1 is a schematic diagram illustrating an example of a recording apparatus according to a first embodiment of the invention. FIG. 3 is an exploded perspective view of the head unit according to the first embodiment of the invention. 2A and 2B are a plan view and a cross-sectional view of the recording head according to Embodiment 1 of the invention. FIG. 5 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment of the invention. FIG. 5 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment of the invention. FIG. 5 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment of the invention. FIG. 5 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment of the invention. It is a top view of the head unit concerning Embodiment 1 of the present invention. It is a figure which shows the density nonuniformity at the time of the printing which concerns on Embodiment 1 of this invention. It is a top view of the head unit concerning Embodiment 2 of the present invention. It is a figure which shows the density nonuniformity at the time of the printing which concerns on Embodiment 2 of this invention.

Explanation of symbols

  I ink jet recording apparatus, 1 ink jet recording head unit, 2, 2A to 2H ink jet recording head, 10 flow path forming substrate, 12 pressure generating chamber, 13 ink supply path, 14 communication path, 15 communication section, 20 nozzle plate, 21 nozzle opening, 21A nozzle row, 30 protective substrate, 40 compliance substrate, 50 elastic film, 55 insulator film, 60 lower electrode film, 70 piezoelectric layer, 80 upper electrode film, 90 lead electrode, 300 piezoelectric element

Claims (6)

An ink jet recording head unit provided with a plurality of nozzle rows in which nozzle openings for discharging ink are arranged in parallel,
Comprising a pair of nozzle rows from which ink of the same color is ejected;
A nozzle row in which the ink discharge amount of ink droplets discharged from the nozzle openings based on the same drive signal tends to gradually decrease from one end side to the other end side of the nozzle row is the ink of the nozzle row An ink jet recording head unit, wherein the pair of nozzle rows are arranged so that the tendency of the discharge amount to gradually reverse each other.   A pair of nozzle rows from which ink of the same color is ejected is displaced in the direction of the nozzle row by a half pitch of the pitch of the nozzle openings arranged in parallel in one nozzle row. 2. An ink jet recording head unit according to claim 1, wherein the ink jet recording head unit is provided.   In a pair of nozzle rows from which ink of the same color is ejected, the nozzle opening at one end of one nozzle row and the nozzle opening at the other end of the other nozzle row are in the same position in the juxtaposition direction of the nozzle openings. The ink jet recording head unit according to claim 1, wherein the ink jet recording head unit is disposed on the head.   The ink jet recording head includes a flow path forming substrate provided with a pressure generating chamber communicating with the nozzle opening, a lower electrode provided in a region facing the pressure generating chamber of the flow path forming substrate, and a piezoelectric body. The inkjet recording head unit according to any one of claims 1 to 3, further comprising: a piezoelectric element including a layer and an upper electrode.   An ink jet recording apparatus comprising the ink jet recording head unit according to claim 1. A method of manufacturing an ink jet recording head unit comprising a plurality of ink jet recording heads each having a nozzle row in which nozzle openings for ejecting ink are arranged in parallel, and a pair of nozzle rows from which ink of the same color is ejected. And
When the ink jet recording head is manufactured, the ink discharge amount of the ink droplets discharged from the nozzle openings based on the same drive signal tends to gradually decrease from the one end side to the other end side of the nozzle row. When the ink jet recording head having the above is formed, the ink jet recording head is arranged in the pair of nozzle rows so that the tendency of the ink discharge amount of the nozzle rows to gradually reverse each other. A method of manufacturing an ink jet recording head unit.

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