JP6423296B2 - Nozzle plate for liquid discharge head, liquid discharge head using the same, and recording apparatus - Google Patents

Description

  The present invention relates to a nozzle plate used for a liquid discharge head, a liquid discharge head using the same, and a recording apparatus.

  The resin that reacts to light is exposed to light, a master die corresponding to the desired nozzle shape is produced, and a metal plating layer is formed around the master die to produce a nozzle plate for use in a liquid discharge head There is a known method (see, for example, Patent Document 1).

JP 2006-175678 A

  However, using a method as described in Patent Document 1, a nozzle plate having a nozzle whose cross-sectional area increases toward the opening through which the liquid is discharged is produced. When a liquid discharge head is manufactured using the same, there is a problem that printing accuracy is low.

  Accordingly, an object of the present invention is to provide a nozzle plate for a liquid discharge head capable of increasing printing accuracy, a liquid discharge head using the same, and a recording apparatus.

  The nozzle plate for a liquid discharge head according to the present invention is a nozzle plate for a liquid discharge head having a plurality of through holes serving as nozzles, and the through holes are at least on the external opening side on which liquid is discharged. A reverse tapered portion having a cross-sectional area that increases toward the external opening, and when viewed from the external opening side, of the plurality of through-holes, the width of the portion of the reverse tapered portion that faces each other The ratio of the through-holes having a difference of more than 1.5 μm is lower than 10%.

  The liquid discharge head of the present invention includes the nozzle plate for the liquid discharge head and a plurality of pressurizing chambers, and the plurality of pressurizing chambers and the plurality of through holes on the opposite side of the external openings. A flow path member joined to the nozzle plate so as to be connected to each of the openings, and a pressurizing unit that applies pressure to the pressurizing chamber are provided.

  The recording apparatus of the invention includes the liquid discharge head, a transport unit that transports a recording medium to the liquid discharge head, and a control unit that controls the liquid discharge head. .

  According to the nozzle plate for a liquid discharge head of the present invention, the accuracy in the direction in which the liquid is discharged is increased, and the printing accuracy can be increased.

(A) is a side view of a recording apparatus including a liquid ejection head according to an embodiment of the present invention, and (b) is a plan view. FIG. 2 is a plan view of a head body that constitutes the liquid ejection head of FIG. 1. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2, and is a plan view in which some flow paths are omitted for explanation. FIG. 3 is an enlarged view of a region surrounded by an alternate long and short dash line in FIG. 2, and is a plan view in which some flow paths are omitted for explanation. (A) is the longitudinal cross-sectional view along the VV line of FIG. 3, (b) is an expanded longitudinal cross-sectional view of the nozzle 8 of (a), (c) is an external opening side of a nozzle. It is the enlarged plan view seen from. (A)-(d) is a schematic sectional drawing of the process in one manufacturing method which manufactures the nozzle plate which concerns on one Embodiment of this invention, (e)-(h) shows the nozzle plate of this invention. It is a schematic sectional drawing of the process in the other manufacturing method to manufacture. (A), (b) is the graph which showed the evaluation result of the nozzle plate which concerns on embodiment of this invention, and a liquid discharge head using the same, (c), (d) is the graph of this invention. It is the graph which showed the evaluation result of the nozzle plate other than embodiment, and the liquid discharge head using the same.

  FIG. 1A is a schematic side view of a color inkjet printer 1 (hereinafter sometimes simply referred to as a printer) which is a recording apparatus including a liquid discharge head 2 according to an embodiment of the present invention. (B) is a schematic plan view. The printer 1 moves the print paper P relative to the liquid ejection head 2 by transporting the print paper P as a recording medium from the guide roller 82 </ b> A to the transport roller 82 </ b> B. The control unit 88 controls the liquid ejection head 2 based on image and character data, ejects liquid toward the recording medium P, causes droplets to land on the printing paper P, and prints on the printing paper P. Record such as.

  In the present embodiment, the liquid discharge head 2 is fixed to the printer 1, and the printer 1 is a so-called line printer. As another embodiment of the recording apparatus of the present invention, the operation of moving the liquid ejection head 2 by reciprocating in the direction intersecting the transport direction of the printing paper P, for example, the direction substantially orthogonal, and the printing paper P There is a so-called serial printer that alternately conveys.

  A flat head mounting frame 70 (hereinafter sometimes simply referred to as a frame) is fixed to the printer 1 so as to be substantially parallel to the printing paper P. The frame 70 is provided with 20 holes (not shown), and the 20 liquid discharge heads 2 are mounted in the respective hole portions, and the portion of the liquid discharge head 2 that discharges the liquid is the printing paper P. It has come to face. The distance between the liquid ejection head 2 and the printing paper P is, for example, about 0.5 to 20 mm. The five liquid ejection heads 2 constitute one head group 72, and the printer 1 has four head groups 72.

  The liquid discharge head 2 has a long and narrow shape in the direction from the front to the back in FIG. 1A and in the vertical direction in FIG. This long direction is sometimes called the longitudinal direction. Within one head group 72, the three liquid ejection heads 2 are arranged along a direction that intersects the conveyance direction of the printing paper P, for example, a substantially orthogonal direction, and the other two liquid ejection heads 2 are conveyed. One of the three liquid ejection heads 2 is arranged at a position shifted along the direction. The liquid discharge heads 2 are arranged so that the printable range of each liquid discharge head 2 is connected in the width direction of the print paper P (in the direction intersecting the conveyance direction of the print paper P) or the ends overlap. Thus, printing without gaps in the width direction of the printing paper P is possible.

The four head groups 72 are arranged along the conveyance direction of the recording paper P. A liquid, for example, ink is supplied to each liquid ejection head 2 from a liquid tank (not shown). The liquid discharge heads 2 belonging to one head group 72 are supplied with the same color ink, and the four head groups 72 can print four color inks. The colors of ink ejected from each head group 72 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). A color image can be printed by printing such ink under the control of the control unit 88.

  The number of the liquid discharge heads 2 mounted on the printer 1 may be one if it is a single color and the range that can be printed by one liquid discharge head 2 is printed. The number of liquid ejection heads 2 included in the head group 72 and the number of head groups 72 can be changed as appropriate according to the printing target and printing conditions. For example, the number of head groups 72 may be increased in order to perform multicolor printing. Also, if a plurality of head groups 72 that print in the same color are arranged and printed alternately in the transport direction, the transport speed can be increased even if the liquid ejection heads 2 having the same performance are used. Thereby, the printing area per time can be increased. Alternatively, a plurality of head groups 72 for printing in the same color may be prepared and arranged so as to be shifted in a direction crossing the transport direction, so that the resolution in the width direction of the print paper P may be increased.

  Further, in addition to printing colored inks, a liquid such as a coating agent may be printed for surface treatment of the printing paper P.

  The printer 1 performs printing on a printing paper P that is a recording medium. The printing paper P is wound around the paper feed roller 80A, passes between the two guide rollers 82A, passes through the lower side of the liquid ejection head 2 mounted on the frame 70, and thereafter It passes between the two conveying rollers 82B and is finally collected by the collecting roller 80B. When printing, the printing paper P is transported at a constant speed by rotating the transport roller 82 </ b> B and printed by the liquid ejection head 2. The collection roller 80B winds up the printing paper P sent out from the conveyance roller 82B. The conveyance speed is, for example, 75 m / min. Each roller may be controlled by the controller 88 or may be manually operated by a person.

  In addition to the printing paper P, the recording medium may be a roll-like cloth. Further, instead of directly transporting the printing paper P, the printer 1 may transport the transport belt directly and transport the recording medium placed on the transport belt. By doing so, sheets, cut cloth, wood, tiles and the like can be used as the recording medium. Furthermore, a wiring pattern of an electronic device may be printed by discharging a liquid containing conductive particles from the liquid discharge head 2. Still further, the chemical may be produced by discharging a predetermined amount of liquid chemical agent or liquid containing the chemical agent from the liquid discharge head 2 toward the reaction container or the like and reacting.

  In addition, a position sensor, a speed sensor, a temperature sensor, and the like may be attached to the printer 1, and the control unit 88 may control each part of the printer 1 according to the state of each part of the printer 1 that can be understood from information from each sensor. . For example, the temperature of the liquid discharge head 2, the temperature of the liquid in the liquid tank, the pressure applied by the liquid in the liquid tank to the liquid discharge head 2, etc. affect the discharge characteristics such as the discharge amount and discharge speed of the discharged liquid. In the case of giving, the drive signal for ejecting the liquid may be changed according to the information.

Next, the head main body 13 constituting the liquid discharge head 2 of the present invention will be described. FIG. 2 is a plan view showing a head body 13 which is a main part of the liquid ejection head 2 shown in FIG. FIG. 3 is an enlarged plan view of a region surrounded by the alternate long and short dash line in FIG. 2 and shows a part of the head main body 13. FIG. 4 is an enlarged plan view of the same position as FIG. In FIG. 3 and FIG. 4, some of the flow paths are omitted for easy understanding. 3 and 4, the pressurizing chamber 10, the squeeze 12 and the discharge hole 8d, which are to be drawn by broken lines below the piezoelectric actuator substrate 21, are drawn by solid lines for easy understanding of the drawings. 5A is a longitudinal sectional view taken along the line VV in FIG. 3, FIG. 5B is an enlarged longitudinal sectional view of the nozzle 8, and FIG. It is the enlarged plan view seen from the opening 8d side.

  The head main body 13 has a flat plate-like channel member 4 and a piezoelectric actuator substrate 21 on the channel member 4. The flow path member 4 is formed by laminating a nozzle plate 31 having nozzles 8 and a flow path member main body on which plates 22 to 30 are laminated. The piezoelectric actuator substrate 21 has a trapezoidal shape, and is disposed on the upper surface of the flow path member 4 so that a pair of parallel opposing sides of the trapezoid is parallel to the longitudinal direction of the flow path member 4. In addition, two piezoelectric actuator substrates 21 are arranged on the flow path member 4 as a whole in a zigzag manner, two along each of the two virtual straight lines parallel to the longitudinal direction of the flow path member 4. Yes. The oblique sides of the piezoelectric actuator substrates 21 adjacent to each other on the flow path member 4 partially overlap in the short direction of the flow path member 4. In the area printed by driving the overlapping piezoelectric actuator substrate 21, the droplets ejected by the two piezoelectric actuator substrates 21 are mixed and landed.

  A manifold 5 that is a part of the liquid flow path is formed inside the flow path member 4. The manifold 5 has an elongated shape extending along the longitudinal direction of the flow path member 4, and an opening 5 b of the manifold 5 is formed on the upper surface of the flow path member 4. A total of ten openings 5 b are formed along each of two straight lines (imaginary lines) parallel to the longitudinal direction of the flow path member 4. The opening 5b is formed at a position that avoids a region where the four piezoelectric actuator substrates 21 are disposed. The manifold 5 is supplied with liquid from a liquid tank (not shown) through the opening 5b.

  The manifold 5 formed in the flow path member 4 is branched into a plurality of branches (the manifold 5 at the branched portion may be referred to as a sub-manifold 5a). The manifold 5 connected to the opening 5 b extends along the oblique side of the piezoelectric actuator substrate 21 and is disposed so as to intersect with the longitudinal direction of the flow path member 4. In the region sandwiched between the two piezoelectric actuator substrates 21, one manifold 5 is shared by the adjacent piezoelectric actuator substrates 21, and the sub-manifold 5 a is branched from both sides of the manifold 5. These sub-manifolds 5 a extend in the longitudinal direction of the head main body 13 adjacent to each other in regions facing the piezoelectric actuator substrates 21 inside the flow path member 4.

  The flow path member 4 has four pressure chamber groups 9 in which a plurality of pressure chambers 10 are formed in a matrix (that is, two-dimensionally and regularly). The pressurizing chamber 10 is a hollow region having a substantially rhombic planar shape with rounded corners. The pressurizing chamber 10 is formed so as to open on the upper surface of the flow path member 4. These pressurizing chambers 10 are arranged over almost the entire surface of the upper surface of the flow path member 4 facing the piezoelectric actuator substrate 21. Therefore, each pressurizing chamber group 9 formed by these pressurizing chambers 10 occupies an area having almost the same size and shape as the piezoelectric actuator substrate 21. Further, the opening of each pressurizing chamber 10 is closed by adhering the piezoelectric actuator substrate 21 to the upper surface of the flow path member 4.

  In the present embodiment, as shown in FIG. 3, the manifold 5 branches into four rows of E1-E4 sub-manifolds 5a arranged in parallel with each other in the short direction of the flow path member 4, and each sub-manifold The pressurizing chambers 10 connected to 5a constitute a row of the pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the four rows are arranged in parallel to each other in the lateral direction. Two rows of the pressure chambers 10 connected to the sub-manifold 5a are arranged on both sides of the sub-manifold 5a.

As a whole, the pressurizing chambers 10 connected from the manifold 5 constitute rows of the pressurizing chambers 10 arranged in the longitudinal direction of the flow path member 4 at equal intervals, and the rows are arranged in 16 rows parallel to each other in the short side direction. ing. The number of pressurizing chambers 10 included in each pressurizing chamber row is arranged so as to gradually decrease from the long side toward the short side corresponding to the outer shape of the displacement element 50 that is an actuator. . The discharge holes 8d are also arranged in the same manner.

  The ejection holes 8d are arranged at substantially equal intervals in the longitudinal direction, which is the resolution direction of the head main body 13, at an interval of about 42 μm (25.4 mm / 150 = 42 μm intervals if 600 dpi). As a result, the head main body 13 can form an image with a resolution of 600 dpi in the longitudinal direction. In the portion where the trapezoidal piezoelectric actuator substrate 21 overlaps, the discharge holes 8d below the two piezoelectric actuator substrates 21 are arranged so as to complement each other. The main body 13 is arranged in the longitudinal direction at an interval corresponding to 600 dpi.

  Moreover, the individual flow paths 32 are connected to the sub manifolds 5a at intervals corresponding to 150 dpi on average. This is because when the discharge holes 8d for 600 dpi are divided and connected to the four sub-manifolds 5a, the individual flow paths 32 connected to the sub-manifolds 5a are not always connected at equal intervals. In other words, the individual flow paths 32 are formed at intervals of an average of 170 μm (25.4 mm / 150 = 169 μm intervals if 150 dpi) in the main scanning direction.

  Individual electrodes 35 to be described later are formed at positions facing the pressurizing chambers 10 on the upper surface of the piezoelectric actuator substrate 21. The individual electrode 35 is slightly smaller than the pressurizing chamber 10, has a shape substantially similar to the pressurizing chamber 10, and is disposed so as to be within a region facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21. ing.

  A large number of discharge holes 8 d are opened on the lower surface of the flow path member 4. The discharge hole 8d is disposed at a position that avoids a region facing the sub-manifold 5a disposed on the lower surface side of the flow path member 4. Further, the discharge hole 8 d is disposed in a region facing the piezoelectric actuator substrate 21 on the lower surface side of the flow path member 4. The discharge hole group, which is a collection of the discharge holes 8, occupies a region having almost the same size and shape as the piezoelectric actuator substrate 21, and the displacement element 50 of the corresponding piezoelectric actuator substrate 21 is displaced from the discharge hole 8d. Droplets can be ejected. The discharge holes 8 d in each region are arranged at equal intervals along a plurality of straight lines parallel to the longitudinal direction of the flow path member 4.

  The flow path member 4 included in the head body 13 has a stacked structure in which a plurality of plates are stacked. These plates are a cavity plate 22, a base plate 23, an aperture (squeezing) plate 24, supply plates 25 and 26, manifold plates 27, 28 and 29, a cover plate 30 and a nozzle plate 31 in order from the upper surface of the flow path member 4. is there. A number of holes are formed in these plates. Each plate is aligned and laminated so that these holes communicate with each other to form the individual flow path 32 and the sub-manifold 5a. As shown in FIG. 5, the head body 13 has the pressurizing chamber 10 on the upper surface of the flow path member 4, the sub-manifold 5 a on the inner lower surface side, and the discharge holes 8 d on the lower surface. Are arranged close to each other at different positions, and the sub-manifold 5a and the discharge hole 8d are connected via the pressurizing chamber 10.

The holes formed in each plate will be described. These holes include the following. First, the pressurizing chamber 10 formed in the cavity plate 22. Secondly, there is a communication hole that constitutes a flow path that connects from one end of the pressurizing chamber 10 to the sub-manifold 5a. This communication hole is formed in each plate from the base plate 23 (specifically, the inlet of the pressurizing chamber 10) to the supply plate 25 (specifically, the outlet of the sub-manifold 5a). The communication hole includes the aperture 12 formed in the aperture plate 24 and the individual supply flow path 6 formed in the supply plates 25 and 26.

  Third, there is a communication hole that constitutes a flow path that communicates from the other end of the pressurizing chamber 10 to the discharge hole 8d, and this communication hole is referred to as a descender (partial flow path) in the following description. The descender is formed on each plate from the base plate 23 (specifically, the outlet of the pressurizing chamber 10) to the nozzle plate 31 (specifically, the discharge hole 8d). On the discharge hole 8d side of the descender, the nozzle 8 formed in the nozzle plate 31 has a particularly small cross-sectional area. The nozzle 8 has a portion with the smallest cross-sectional area in the middle of the thickness direction, a tapered portion 8a whose cross-sectional area increases from the portion toward the internal opening 8c of the nozzle 8, and a nozzle from the portion. It has a reverse taper portion 8b whose cross-sectional area increases toward 8 discharge holes (sometimes referred to as external openings) 8d. The shape of the nozzle 8 will be described later.

  Fourthly, there is a communication hole constituting the sub-manifold 5a. The communication holes are formed in the manifold plates 27-30.

  Such communication holes are connected to each other to form an individual flow path 32 extending from the liquid inflow port (outlet of the submanifold 5a) from the submanifold 5a to the discharge hole 8d. The liquid supplied to the sub-manifold 5a is discharged from the discharge hole 8d through the following path. First, from the sub-manifold 5a, it passes through the individual supply flow path 6 and reaches one end of the aperture 12. Next, it proceeds horizontally along the extending direction of the aperture 12 and reaches the other end of the aperture 12. From there, it reaches one end of the pressurizing chamber 10 upward. Furthermore, it progresses horizontally along the extending direction of the pressurizing chamber 10 and reaches the other end of the pressurizing chamber 10. While moving little by little in the horizontal direction from there, it proceeds mainly downward and proceeds to the discharge hole 8d opened on the lower surface.

  As shown in FIG. 5, the piezoelectric actuator substrate 21 has a laminated structure including two piezoelectric ceramic layers 21a and 21b. Each of these piezoelectric ceramic layers 21a and 21b has a thickness of about 20 μm. The thickness of the displacement element 50, which is the portion where the piezoelectric actuator substrate 21 is displaced, is about 40 μm, and the displacement amount can be increased by being 100 μm or less. Each of the piezoelectric ceramic layers 21a and 21b extends so as to straddle the plurality of pressure chambers 10 (see FIG. 3). The piezoelectric ceramic layers 21a and 21b are made of a lead zirconate titanate (PZT) ceramic material having ferroelectricity.

  The piezoelectric actuator substrate 21 has a common electrode 34 made of a metal material such as Ag—Pd and an individual electrode 35 made of a metal material such as Au. As described above, the individual electrode 35 is disposed at a position facing the pressurizing chamber 10 on the upper surface of the piezoelectric actuator substrate 21. One end of the individual electrode 35 is composed of an individual electrode body 35 a facing the pressurizing chamber 10 and an extraction electrode 35 b that is led out of the region facing the pressurizing chamber 10.

Since the piezoelectric ceramic layers 21a and 21b and the common electrode 34 have substantially the same shape, warpage can be reduced when they are produced by simultaneous firing. The piezoelectric actuator substrate 21 of 100 μm or less is likely to be warped during the firing process, and the amount thereof is also increased. In addition, if warpage occurs, the warp is deformed and bonded when laminated on the flow path member 4, and the deformation at that time affects the characteristic variation of the displacement element 50, and thus the liquid ejection characteristics. Therefore, the warp is preferably as small as the thickness of the piezoelectric actuator substrate 21 or less. And in order to reduce the curvature by the difference of the baking shrinkage | contraction behavior of a place with an internal electrode and a place without an internal electrode, the internal electrode 34 is formed with a solid without a pattern inside. Here, when the shape is substantially the same, it means that the difference in the dimensions of the outer periphery is within 1% of the width of the portion. Since the outer circumferences of the piezoelectric ceramic layers 21a and 21b are basically cut and formed in a state of being stacked before firing, they are at the same position within the range of processing accuracy. The internal electrode 34 is also less likely to warp if it is formed by cutting simultaneously with the piezoelectric ceramic layers 21a and 21b after solid printing, but by printing with a slightly smaller pattern similar to the piezoelectric ceramic layers 21a and 21b. Since the internal electrode 34 is not exposed on the side surface of the piezoelectric actuator 21, the electrical reliability is increased.

  Although details will be described later, a drive signal (drive voltage) is supplied to the individual electrode 35 from the control unit 88 through an FPC (Flexible Printed Circuit) which is an external wiring. The drive signal is supplied in a constant cycle in synchronization with the conveyance speed of the print medium P. The common electrode 34 is formed over almost the entire surface in the area between the piezoelectric ceramic layer 21a and the piezoelectric ceramic layer 21b. That is, the common electrode 34 extends so as to cover all the pressurizing chambers 10 in the region facing the piezoelectric actuator substrate 21. The thickness of the common electrode 34 is about 2 μm. The common electrode 34 is grounded in a region not shown, and is held at the ground potential. In the present embodiment, a surface electrode (not shown) different from the individual electrode 35 is formed on the piezoelectric ceramic layer 21b at a position avoiding the electrode group composed of the individual electrodes 35. The surface electrode is electrically connected to the common electrode 34 through a through hole formed in the piezoelectric ceramic layer 21b, and is connected to external wiring in the same manner as the large number of individual electrodes 35.

  As will be described later, when a predetermined drive signal is selectively supplied to the individual electrode 35, pressure is applied to the liquid in the pressurizing chamber 10 corresponding to the individual electrode 35. As a result, droplets are discharged from the corresponding discharge holes 8 through the individual flow paths 32. That is, the portion of the piezoelectric actuator substrate 21 that faces each pressure chamber 10 corresponds to an individual displacement element 50 (actuator) corresponding to each pressure chamber 10 and the discharge hole 8. That is, in the laminate composed of two piezoelectric ceramic layers, the displacement element 50 having a unit structure as shown in FIG. 5 is positioned immediately above the pressurizing chamber 10 for each pressurizing chamber 10. The diaphragm 21a, the common electrode 34, the piezoelectric ceramic layer 21b, and the individual electrode 35 are formed. The piezoelectric actuator substrate 21 includes a plurality of displacement elements 50. In the present embodiment, the amount of liquid discharged from the discharge hole 8 by one discharge operation is about 5 to 7 pL (picoliter).

  When the piezoelectric actuator substrate 21 is viewed in plan, the individual electrode main body 35a is disposed so as to overlap the pressurizing chamber 10, and the individual electrode 35, the common electrode 34, and the individual electrode 35 located at the center of the pressurizing chamber 10 are arranged. The piezoelectric ceramic layer 21 b sandwiched between the two is polarized in the stacking direction of the piezoelectric actuator substrate 21. The direction of polarization may be either upward or downward, and driving can be performed by giving a drive signal corresponding to the direction.

  As shown in FIG. 5, the common electrode 34 and the individual electrode 35 are disposed so as to sandwich only the uppermost piezoelectric ceramic layer 21b. A region sandwiched between the individual electrode 35 and the common electrode 34 in the piezoelectric ceramic layer 21b is called an active portion, and the piezoelectric ceramic in that portion is polarized in the thickness direction. In the piezoelectric actuator substrate 21 of the present embodiment, only the uppermost piezoelectric ceramic layer 21b includes an active portion, and the piezoelectric ceramic 21a does not include an active portion and functions as a diaphragm. The piezoelectric actuator substrate 21 has a so-called unimorph type configuration.

In an actual driving procedure in the present embodiment, the individual electrode 35 is set to a potential higher than the common electrode 34 (hereinafter referred to as a high potential) in advance, and the individual electrode 35 is temporarily set to the same potential as the common electrode 34 every time there is a discharge request. (Hereinafter referred to as a low potential), and then set to a high potential again at a predetermined timing. As a result, the piezoelectric ceramic layers 21a and 21b return to their original shapes at the timing when the individual electrodes 35 become low potential, and the volume of the pressurizing chamber 10 increases compared to the initial state (the state where the potentials of both electrodes are different). To do. At this time, a negative pressure is applied to the pressurizing chamber 10 and the liquid is sucked into the pressurizing chamber 10 from the manifold 5 side. Thereafter, at the timing when the individual electrode 35 is set to a high potential again, the piezoelectric ceramic layers 21a and 21b are deformed so as to protrude toward the pressurizing chamber 10, and the pressure in the pressurizing chamber 10 is reduced due to the volume reduction of the pressurizing chamber 10. The pressure becomes positive and the pressure on the liquid rises, and droplets are ejected. That is, a drive signal including a pulse based on a high potential is supplied to the individual electrode 35 in order to eject a droplet. The ideal pulse width is AL (Acoustic Length), which is the length of time during which the pressure wave propagates from the manifold 5 to the discharge hole 8d in the pressurizing chamber 10. According to this, when the inside of the pressurizing chamber 10 is reversed from the negative pressure state to the positive pressure state, both pressures are combined, and the liquid droplets can be discharged at a stronger pressure.

  As described above, the nozzle 8 is a through hole formed in the nozzle plate 31. The thickness of the nozzle plate 31, that is, the length of the nozzle 8 is 20 to 100 μm. In order to reduce the fluid resistance of the nozzle 8, it is desirable to make it as thin as possible. However, if it is too thin, handling in manufacturing becomes difficult, so an optimum value is set with a compatible thickness. The cross-sectional shape of the nozzle 8 is preferably a circular shape, but may be a rotationally symmetric shape such as an elliptical shape, a triangular shape, or a rectangular shape. The narrowest portion of the cross section of the nozzle 8 has, for example, a circular shape having a diameter of 10 to 60 μm. The nozzle hole diameter is a control factor for setting the discharge amount, and is set according to a desired discharge amount. One opening of the nozzle 8 is an external opening 8d which is open to the outside of the flow path member 4 and is an opening on the side from which the liquid is discharged. Also. The other opening of the nozzle 8 opens toward the inside of the flow path member 4 and is an internal opening 8c that is an opening on the side to which the liquid is supplied.

  The nozzle 8 includes, on the side of the external opening 8d, a reverse tapered portion 8b whose opening cross-sectional area increases toward the external opening 8d. When viewed from the external opening 8d side, the reverse tapered portion 8b appears as an annular region around a circular portion that penetrates the nozzle plate 31. When viewed from the side of the external opening 8d, the width of the reverse tapered portion 8b is substantially constant. This is the same when the shape of the nozzle 8 is not circular.

  More specifically, the difference between the widths of the opposing portions of the reverse tapered portion 8b is basically 1.5 μm or less. The difference in width is preferably 1.0 μm or less. Among the plurality of nozzles 8, the ratio of the nozzles 8 having a difference in the width of the opposed portions of the reverse tapered portion 8 b that is greater than 1.5 μm is lower than 10%. The ratio is further lower than 5%, particularly preferably lower than 2%, and it is further preferable that the difference in width is 1.5 μm or less in all the nozzles 8. Unless otherwise specified below, the width of the inverse tapered portion 8b indicates the width when viewed from the external opening 8d side.

  Although details will be described later, the difference in width affects the liquid ejection direction. Therefore, in the liquid discharge head 2, the difference in the width in the longitudinal direction of the liquid discharge head 2 in which the nozzles 8 are arranged in the printing resolution direction is particularly important. In the nozzle plate 31, the nozzles 8 are arranged at substantially equal intervals in the direction that is the printing resolution.

  In FIG. 5C, L1 is an imaginary straight line along the longitudinal direction of the liquid ejection head 2, and the width of the portion of the reverse taper portion 8b facing the L1 is T1a [μm]. T1b [μm]. The difference between the widths of the facing portions is an absolute value of T1a [μm] −T1b [μm], and this value is 1.5 μm or less.

  L2 is a direction in which the liquid ejection head 2 and the recording paper P are relatively conveyed during printing. The difference between the widths of the opposing portions of the reverse tapered portion 8b along L2 is T2a [μm] −T2b [μm], and this value is also preferably 1.5 μm or less. L3 and L4 are imaginary straight lines inclined by 45 degrees with respect to L1, and the difference in the widths of the opposing portions of the inversely tapered portion 8b along L1 to 4 is measured at four locations. If it is 0.5 μm or less, it can be confirmed that the overall width of the reverse tapered portion 8b is substantially constant.

The average width of the reverse tapered portion 8b is preferably 1 μm or less. Here, the average width of the reverse tapered portion 8b is an average value of T1a, T1b, T2a, and T2b. The average width of the reverse tapered portion 8b may be calculated by dividing the area of the reverse tapered portion 8b when viewed from the external opening 8d side by the length of the outer periphery of the external opening 8b. Further, the length of the reverse tapered portion 8b, in other words, the depth of the reverse tapered portion 8b is preferably 10 μm or less, and more preferably 5 μm or less. The longer the reverse tapered portion 8b is, the more easily the meniscus position at the time of ejection varies, and the ejection direction tends to vary. Therefore, the shorter length of the inverse tapered portion 8b is preferable.

  The nozzle 8 includes a tapered portion 8a on the side of the internal opening 8c, in which the cross-sectional area of the opening increases toward the internal opening 8c. The internal opening 8 c of the tapered portion 8 a is inclined at an angle θ with respect to the direction orthogonal to the nozzle plate 31. θ is preferably 10 to 30 degrees. The inclination of the tapered portion 8a is substantially constant over half or more of the length of the tapered portion 8a on the inner opening 8c side. When the inclination is almost constant, the inclination gradually becomes gentler, and the portion having the smallest cross-sectional area is connected to the reverse tapered portion 8b. There is no corner that changes abruptly at the boundary between the tapered portion 8a and the reverse tapered portion 8b, and the angle changes smoothly from the tapered portion 8a to the reverse tapered portion 8b.

  Here, the shape of the inner surface of the nozzle 8 located in a certain direction from the central axis of the nozzle 8 will be considered. The distance from the central axis is long on the side of the internal opening 8c, and the distance from the center is shortened from the internal opening 8c toward the external opening 8d, and the distance is the shortest at a certain place. This place is the boundary between the tapered portion 8a and the reverse tapered portion 8b, and is referred to as the closest contact A. The nozzle 8 ideally has a shape of a rotating body with respect to the central axis, and it is preferable that the depth of the closest point A, that is, the distance from the external opening 8d does not change for each angle viewed from the central axis. However, some variation in manufacturing occurs. When the closest point A is a corner where the angle changes abruptly and there is a large variation in the position of the closest point A in the depth direction for each angle from the central axis, the variation in the discharge direction also increases. Therefore, it is preferable that there is no corner from the tapered portion 8a to the reverse tapered portion 8b, and the angle is smoothly changed.

  When the relationship between the printing accuracy and the shape of the nozzle 8 is examined for the liquid discharge head 2 including the nozzle 8 having the taper portion 8a and the reverse taper portion 8b, it is related to the formation variation of the width of the reverse taper portion 8b and the liquid discharge direction. I found out that Specifically, the discharge direction tends to be shifted in the direction in which the reverse tapered portion 8b is wide. When the rear end of the discharged liquid (hereinafter sometimes referred to as a tail) tends to be separated from the reverse taper portion 8b, the tail is offset from the position where the tail is biased toward the wide side of the reverse taper portion 8b. Going to the outside. When this tail catches up with the main body of the discharged liquid, it is considered that a force toward the wider direction of the reverse tapered portion 8b is applied.

  If the difference in the width of the reverse taper portion 8b of the opposing portion of the inner surface is 1.5 μm or less, this influence can be reduced, the accuracy in the ejection direction can be increased, and the printing accuracy can be increased. In order to confirm the formation accuracy of the nozzles 8 in the liquid discharge head 2, for example, the widths T1a and T1b of the reverse tapered portions 8b in the L1 direction are measured for ten nozzles 8 and the differences are all 1.5 μm or less. It may be confirmed that the ratio of the nozzles 8 having a width difference larger than 1.5 μm is lower than 10%. If the number of nozzles 8 of the liquid ejection head 2 is less than 10, all the nozzles 8 are measured, and it is only necessary to confirm that the difference in width between all the nozzles 8 is 1.5 μm or less. In order to confirm that the ratio of the nozzles 8 having a width difference larger than 1.5 μm is lower than 5%, the number of measurements may be measured by measuring 20 nozzles to confirm that there is no such thing. In order to confirm that the ratio of the nozzles 8 having a width difference larger than 1.5 μm is lower than 2%, 50 nozzles may be measured to confirm that there is no such thing. Moreover, you may measure the difference of a width | variety also about the direction of L2, L3, L4 as needed.

  Further, the surface roughness of the inner surface of the nozzle 8 is smaller in the reverse tapered portion 8b than in the tapered portion 8a. Thereby, it can suppress that the discharge direction varies by the influence of the unevenness on the reverse tapered portion 8b side. If the surface roughness of the reverse taper portion 8b is large, the tail is delayed from separating from the reverse taper portion 8b, so that the influence of the difference in the width of the reverse taper portion 8b increases, or the position where the tail finally leaves is the surface. It is thought that it is difficult to occur because there is an effect such as variation due to the effect of roughness. The surface roughness of the inner surface of the nozzle 8 can be measured by cutting the nozzle 8 in the vertical direction. The surface roughness of the tapered portion 8b is, for example, Rmax 0.13 to 0.25 μm, and the surface roughness of the reverse tapered portion 8b is, for example, Rmax 0.10 to 0.15 μm. If the surface roughness of the reverse tapered portion 8b is 0.02 μm or more smaller than the surface roughness of the tapered portion 8a, it is preferable because variations in the ejection direction can be further suppressed.

  Subsequently, two manufacturing methods for manufacturing the nozzle plate 31 including such nozzles 8 will be described. First, a manufacturing method using a negative type photoresist in which the exposed portion is cured will be described, and then a manufacturing method using a positive type photoresist in which the exposed portion is dissolved will be described.

  6A to 6D are longitudinal sectional views in each step of the method of manufacturing the nozzle plate 31 using a negative photoresist. First, an electroformed substrate 102 made of a metal such as stainless steel is prepared. The surface of the electroformed substrate 102 on the side where the nozzle plate 31 is formed by plating in a process described later is polished to Rmax 100 nm or less. As shown in FIG. 6A, a negative photoresist film 104 is formed on the polished surface side of the electroformed substrate 102. The photoresist film 104 is formed by applying a liquid photoresist by a method such as spin coating or by thermocompression bonding a dry film type resist.

  A photomask 106 on which a mask pattern is formed so that the nozzle 8 can be formed with a desired size and arrangement is prepared. As shown in FIG. 6B, the photoresist film 104 is exposed through the photomask 106. The light source may be a g-line (wavelength 436 nm), i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), or the like of a high-pressure mercury lamp.

  The photomask 106 transmits light only at the portion that becomes the nozzle 8, and the photoresist film 104 located in the opening is exposed to light and cured (the cured portion is cured below). Part) Due to the light diffraction phenomenon, the diffracted light spreads outside the opening of the photomask 106. In the vicinity of the boundary of the opening, the amount of sensitized light is reduced by the amount of diffracted light spreading outside. Basically, this effect increases as the distance from the photomask 106 increases. Therefore, as the distance from the photomask 106 increases, the range of the hardened portion gradually decreases. Thereby, the shape used as the taper part 8a is formed.

  However, the photoresist film 104 immediately above the electroformed substrate 102 is also exposed by light reflected at the interface between the electroformed substrate 102 and the photoresist film 104. For this reason, the size of the hardened portion increases in the vicinity of this interface. Since the reflected light is diffused and attenuated in the photoresist film 104, the size of the hardened portion gradually decreases as the distance from the interface increases. Further away from the interface, it leads to the shape of the tapered portion 8a, and the size of the hardened portion increases. The influence of the reflected light is in the range of about 1 to 10 μm from the interface between the electroformed substrate 102 and the photoresist film 104. Thereby, the hardening part which becomes the shape which changes an angle gradually from the reverse taper part 8b and the reverse taper part 8b to the taper part 8a can be formed. In the positive type manufacturing method, since the angle from the reverse tapered portion 8b to the tapered portion 8a is smoothly and gradually changed, it is preferable to produce the positive type rather than the negative type.

Here, since the surface on which the photoresist film 104 is formed is polished as described above, the light reflected by the electroformed substrate 102 is reflected almost uniformly on the side of the nozzle 8 that becomes the external opening 8d. Is done. Thereby, the dispersion | variation by the position of the shape of the hardening part of the photoresist film 104 used as the reverse taper part 8b of the nozzle 8 can be made small. If the polishing is insufficient, there are irregularities, or there is a portion with low reflectance, a difference in intensity is generated in the reflected light depending on the position in the nozzle 8. If there is a portion where the reflected light is weak, curing does not proceed at that portion, so the reverse tapered portion 8a becomes small, and the width of the reverse tapered portion 8a also becomes small. On the contrary, if there is a portion where the reflected light is strong, curing proceeds at that portion, so the reverse tapered portion 8a becomes large and the width of the reverse tapered portion 8a also becomes large. If there is such a portion, the difference in the width of the reverse tapered portion 8a at the opposite portion of the inner surface of the nozzle width becomes large.

  When the uncured photoresist film 104 is removed, the cured portion of the photoresist film 104, which is the basis of the shape of the nozzle 8, remains patterned as shown in FIG. At this time, if necessary, rinse with ultrapure water or the like so that unnecessary portions do not easily remain.

  The nozzle plate 31 is produced by forming the plating film 31 on the electroformed substrate 102 on which the patterned photoresist film 104 prepared as described above is formed. The electroformed substrate 102 is immersed in a plating solution containing Ni, Cu, Cr, Ag, W, Pt, Pd, Rd, etc., and electricity is allowed to flow, so that a photoresist film 104 is formed as shown in FIG. A plating film 31 is formed on the surface of the electroformed substrate 102 on which is disposed. For example, the plating film 31 is mainly composed of Ni. The formation of the plating film 31 is stopped by time management or the like before reaching the height of the photoresist film 104, so that the nozzle plate 31 has a predetermined thickness. Subsequently, the photoresist film 104 inside the nozzle 8 is removed using an organic solvent or the like. Further, the nozzle plate 31 is peeled from the electroformed substrate 102.

  In this manner, the nozzle plate 31 including the nozzle 8 having the tapered portion 8a and the reverse tapered portion 8b can be manufactured. If necessary, a water repellent (ink repellent) film or the like may be formed on the surface of the nozzle plate 31 on the side of the external opening 8d with a fluororesin or carbon.

  In addition, you may make it accelerate | stimulate hardening reaction beforehand before performing exposure. The heating process can be easily controlled by using an oven, a hot plate or the like. In addition, since the heating reaction further accelerates the curing reaction on the electroformed substrate 102 side in the photoresist film 104, the surface roughness of the side surface of the photoresist film 104 after development is on the side far from the electroformed substrate 102. Thus, the side closer to the electroformed substrate 102 becomes smaller. The surface roughness of the side surface of the photoresist film 104 after development is transferred to the nozzle 8 and becomes the surface roughness of the inner surface of the nozzle 8. Therefore, when manufactured as described above, the surface roughness of the reverse tapered portion 8b can be made smaller than the surface roughness of the tapered portion 8a. By reducing the surface roughness of the reverse tapered portion 8b that has a great influence on the discharge characteristics, variations in the discharge characteristics can be reduced.

  FIGS. 6E to 6H are longitudinal sectional views in respective steps of the method for manufacturing the nozzle plate 31 using a positive photoresist.

In FIG. 6 (e), a positive type photoresist film 204 is formed on one surface of the electroformed substrate 202. The electroformed substrate 202 may be almost the same as that used in the negative type described above, but polishing of the surface on the photoresist film 204 side is not necessarily required. In this manufacturing process, since the interface side between the electroformed substrate 202 and the photoresist film 204 is the side of the internal opening 8c of the nozzle 8, the internal opening is affected by the reflected light at the interface between the electroformed substrate 202 and the photoresist film 204. This is because even if the formation accuracy on the 8c side varies, the influence on the ejection characteristics is low compared to the case where the shape on the external opening 8d side varies. However, by polishing, the internal opening 8
Since c-side formation accuracy can be increased and variation in ejection characteristics can be reduced, polishing is preferably performed. The positive photoresist film 204 can be formed by a method similar to that for the negative photoresist film 104.

  In FIG. 6F, the photomask 206 shields light only from the portion serving as the nozzle 8, and the photoresist film 204 located at the other transmitting portion is dissolved and removed. Similar to the manufacturing process of the nozzle plate 31 using the negative photoresist, the diffracted light spreads inward from the light shielding portion of the photomask 206 due to the light diffraction phenomenon. In the vicinity of the boundary of the light shielding part, the amount of sensitization decreases by the amount of diffracted light spreading inward. Basically, this effect increases as the distance from the photomask 206 increases. Therefore, as the distance from the photomask 106 increases, the area to be dissolved and removed gradually decreases. Thereby, the shape which becomes the taper part 8a like FIG.6 (g) is formed. In FIG. 6H, the plating film 31 is formed in the same manner as in the manufacturing process using a negative photoresist. Although the description of the negative type manufacturing method is omitted, in the vicinity of the photoresist film 204, the formation rate of the plating film 31 is slower than the surroundings. For this reason, in the vicinity of the photoresist film 204, the growth of the plating film 31 is delayed, and a curved portion 31a in which the thickness of the plating film 31 gradually decreases toward the photoresist film 204 is formed. This phenomenon occurs in both the positive-type and negative-type manufacturing processes, but in the positive-type process, the dimension of the curved portion 31a varies due to variations in the thickness of the plating film 31 in the vicinity of the photoresist film 204.

  The curved portion 31a has a shape that is the basis of the reverse tapered portion 8b. However, only by managing the process conditions of the plating film 31, the curved portion 31a is curved with high accuracy so that the variation in the width of the reverse tapered portion 8b is within a desired range. It is difficult to form the portion 31a. Therefore, after removing the residue of the photoresist film 204 and peeling the nozzle plate 31 from the electroformed substrate 202, the nozzle plate 31 is polished from the curved portion 31a side, that is, from the external opening 8b side. This polishing can be performed by various methods such as lapping, buffing, chemical polishing, and electrolytic polishing. Since there is a difference in the shape of the curved portion 31a depending on the location of the nozzle plate 31, by adjusting the polishing amount depending on the location, the difference in the width of the opposite portion of the inverse tapered portion 8b is made 1.5 μm or less.

  The nozzle plate 31 was manufactured by a negative type manufacturing method, and the relationship between the width of the reverse tapered portion 8b and the variation in the ejection direction was examined. In the process of producing the nozzle plate 31, the nozzle plate 31 of the present invention produced by polishing the surface of the electroformed substrate 102 to Rmax 100 nm and the electroformed substrate 102 of Rmax 2 μm, which is outside the scope of the present invention. Was made. Using these nozzle plates 31, the liquid discharge head 2 shown in FIGS. 2, 3, 4 and 5 (a) was produced and evaluated.

  The shape of the produced nozzle 8 is as follows: the thickness of the nozzle 8 is 40 μm, the thickness of the tapered portion 8 a is 35 μm, the thickness of the reverse tapered portion 8 b is 5 μm, the external opening 8 d is circular and has a diameter of 20 μm, and the average width of the reverse tapered portion 8 b is 1 It was 5 μm. FIG. 7A shows the difference between the width of the reverse tapered portion 8b and the deviation of the landing position in the liquid discharge head 2 manufactured using the nozzle plate 31 manufactured by polishing the surface of the electroformed substrate 102 to Rmax 100 nm. It is the graph which showed the relationship. FIG. 7B is a graph showing the frequency of occurrence of the difference in the width of the inverse tapered portion 8b at that time. In the graph, “0.1 to 0.3” or the like represents 0.1 or more and less than 0.3.

  FIGS. 7C and 7D are graphs showing the same evaluation results of the liquid discharge head 2 manufactured using the nozzle plate 31 in which the surface of the electroformed substrate 102 is manufactured at Rmax 2 μm.

In the evaluation, for 50 nozzles 8, the difference in the width of the reverse tapered portion 8 b and the deviation of the landing position in the longitudinal direction of the liquid ejection head 2 were measured. The nozzles 8 to be measured were randomly determined so as to be distributed almost uniformly over the entire nozzle plate 31 of the liquid ejection head 2. The nozzles 8 evaluated by the two liquid discharge heads 2 were assumed to be at the same position.

  As shown in FIG. 5C, the difference in the width of the reverse taper portion 8b is the opposite reverse taper portion 8b of the portion intersecting the imaginary line L1 along the longitudinal direction of the liquid ejection head 2. T1a [μm] and T1b [μm] were measured. In the graphs of FIGS. 7A to 7D, the values of these differences T1a-T1b are shown. That is, if the value of the width of the reverse tapered portion 8b in the graph is positive, the width of the reverse tapered portion 8b on the right side of FIG. 5C is large, and if the width is negative, the reverse tapered portion on the left side of FIG. The width of the portion 8b is large.

  Regarding the displacement of the landing position, the displacement in the longitudinal direction of the liquid ejection head 2 was measured out of the displacement of the landing position of the liquid landed at a position 1 mm away from the ejection hole 8d. If the landing position shift is a positive value, it indicates a shift to the right in FIG.

  7A and 7C, the landing position is shifted to the wide side of the reverse tapered portion 8b, and the liquid flying direction tends to the wide side of the reverse tapered portion 8b. I understand that there is.

  In the evaluation of FIGS. 7A and 7B, the ratio of the nozzles 8 in which the width difference between the opposed portions of the reverse tapered portion 8b is greater than 1.5 μm is 0 out of 50, and 0 %, The proportion was lower than 10%. That is, the liquid ejection head 2 evaluated in FIGS. 7A and 7B includes the nozzle plate 31 within the range of the present invention, and the absolute value of the landing position deviation in the evaluated nozzle 8 is 5 at the maximum. It was as small as 8 μm. Further, the liquid discharge head 2 was capable of good printing at 600 dpi.

  On the other hand, in the evaluation of FIGS. 7C and 7D, the ratio of the nozzles 8 in which the width difference between the opposed portions of the reverse tapered portion 8b is larger than 1.5 μm is 50 out of 50. 11 pieces were 12%, and the ratio was 10% or more. That is, the liquid ejection head 2 evaluated in FIGS. 7C and 7D includes the nozzle plate 31 outside the range of the present invention, and the absolute value of the landing position deviation in the evaluated nozzle 8 is 23 at the maximum. Increased to 9 μm. Further, this liquid discharge head 2 was inferior to the above-described liquid discharge head 2 in printing results at 600 dpi.

DESCRIPTION OF SYMBOLS 1 ... Printer 2 ... Liquid discharge head 4 ... Flow path member 5 ... Manifold 5a ... Sub manifold 5b ... Manifold opening 6 ... Individual supply flow path 8 ... Nozzle 8a ... Tapered portion 8b ... Reverse tapered portion 8c ... Internal opening 8d ... Discharge hole (external opening)
DESCRIPTION OF SYMBOLS 9 ... Pressurizing chamber group 10 ... Pressurizing chamber 11a, b, c, d ... Pressurizing chamber row 12 ... Squeezing 13 ... Head body 15a, b, c, d ... Discharge hole array 21 ... Piezoelectric actuator substrate 21a ... Piezoelectric ceramic layer (ceramic diaphragm)
21b ... Piezoelectric ceramic layer 22-30 ... Plate 31 ... Plate (nozzle plate), plating film 31a ... Curved part 32 ... Individual flow path 34 ... Common electrode 35 ... Individual Electrode 35a ... Individual electrode body 35b ... Lead electrode 36 ... Connection electrode 50 ... Displacement element 70 ... Head mounting frame 72 ... Head group 80A ... Paper feed roller 80B ... Recovery roller 82A ... guide roller 82B ... conveying roller 88 ... control unit 102,202 ... electroformed substrate 104,204 ... photoresist film 106,206 ... photomask A ... Nearest contact point P: Printing paper T1a, T1b: Width of reverse taper part (opposite each other) T2a, T2b ... Width of reverse taper part (opposite each other)

Claims (8)

A nozzle plate for a liquid discharge head having a plurality of through holes to be nozzles,
The through hole is provided with a reverse taper portion whose cross-sectional area increases toward the external opening at least on the external opening side that is a side from which liquid is discharged,
When viewed from the external opening side,
A nozzle plate for a liquid discharge head, wherein a ratio of the through holes having a difference in width of the opposed portions of the reverse taper portion of the plurality of through holes being greater than 1.5 μm is lower than 10%. .   The through holes in one direction have a group of through holes in which the arrangement of the through holes is substantially equidistant. Among the through holes belonging to the group of through holes, the reverse tapered portion in the one direction is opposed to the reverse tapered part. 2. The nozzle plate for a liquid discharge head according to claim 1, wherein a ratio of the through holes having a width difference of more than 1.5 μm is lower than 10%.   3. The nozzle plate for a liquid discharge head according to claim 1, wherein the through-hole has a tapered portion whose cross-sectional area increases toward an opening opposite to the external opening.   4. The nozzle plate for a liquid discharge head according to claim 3, wherein the through hole is constituted by the reverse tapered portion and the tapered portion. A nozzle plate for a liquid discharge head having a plurality of through holes to be nozzles,
The through hole is provided with a reverse taper portion whose cross-sectional area increases toward the external opening at least on the external opening side that is a side from which liquid is discharged,
When viewed from the external opening side,
Among the plurality of through-holes, a ratio of the through-holes having a difference in width of the opposed portions of the reverse taper portion of greater than 1.5 μm is lower than 10%,
The through-hole has a tapered portion whose cross-sectional area increases toward the opening opposite to the external opening ,
Wherein the inner surface of the through hole, the surface roughness of the reverse tapered portion, you being smaller than the surface roughness of the tapered portion the liquid discharge head nozzle plate. 5. The nozzle plate for a liquid discharge head according to claim 4, wherein a surface roughness of the reverse tapered portion is 0.02 μm or less smaller than a surface roughness of the tapered portion on the inner surface of the through hole. A nozzle plate for a liquid ejection head according to any one of claims 1 to 6,
A flow path member main body having a plurality of pressurizing chambers and joined to the nozzle plate such that the plurality of pressurizing chambers and the openings on the opposite sides of the external openings of the plurality of through holes are connected to each other; ,
A liquid discharge head comprising: a pressurizing unit that applies pressure to the pressurizing chamber.   8. A recording apparatus comprising: the liquid ejection head according to claim 7; a conveyance unit that conveys a recording medium to the liquid ejection head; and a control unit that controls the liquid ejection head.