JPWO2018179706A1 - Ink jet recording device - Google Patents

Abstract

Provided is an inkjet recording apparatus capable of suppressing occurrence of ink ejection failure. A nozzle forming member provided with a nozzle hole communicating with the ink storage unit, and a driving unit that outputs a drive signal for causing the pressure fluctuation unit to perform a pressure fluctuation operation of fluctuating the pressure of the ink in the ink storage unit, The first portion and the second portion of the nozzle hole have a monotonous non-decreasing cross-sectional area as the distance from the ink ejection port increases, and the first opening of the first portion at the connection surface of the first portion and the second portion. The driving portion is connected in a positional relationship included in the second opening of the second portion, and causes the driving portion to perform a pressure fluctuation operation of drawing the surface of the ink in the nozzle hole toward the ink storing portion from the second opening. A driving signal is supplied, and the opening width in any direction passing through the center of the first opening is D, and the maximum value of the distance between the edge of the first opening and the edge of the second opening along the direction. Is L, 0 <L ≦ 0.25 Meet.

Description

  The present invention relates to an inkjet recording device.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus that changes the pressure of ink in an ink storage unit to discharge ink to a recording medium from an ink discharge port of a nozzle communicating with the ink storage unit, and records an image on the recording medium. There is. 2. Description of the Related Art As a nozzle in an ink jet recording apparatus, a nozzle formed by providing a nozzle hole communicating with an ink reservoir in a nozzle forming member such as a resin plate is widely used.

  In an ink jet recording apparatus using such a nozzle forming member, the distribution of the cross-sectional area in a cross section of the nozzle hole parallel to the ink ejection port is monotonically non-decreasing (in a broad sense monotonically increasing) as the distance from the ink ejection port increases. A technology that discharges minute ink while improving the ink discharge efficiency by suppressing the influence of the drag received from the wall by the ink flowing toward the ink discharge port inside the nozzle hole by providing the nozzle hole in the shape of (For example, Patent Document 1). Further, the nozzle hole has a shape having a first portion having one end forming an ink ejection port and a second portion connected to the other end of the first portion, and the first portion and the second portion are connected. In the connection surface to be formed, the respective parts are connected in a shape and a positional relationship such that the opening (first opening) of the first part is included in the opening (second opening) of the second part. There is known a nozzle in which a shelf-shaped step (shelf-shaped portion) is generated on the connection surface (for example, Patent Document 2). According to such a nozzle, even if an error occurs in the formation position of the first portion and the second portion, the shape of the first portion is not affected as long as the error is within the width of the shelf portion. It is possible to suppress the occurrence of the problem that the ink ejection direction is bent due to the difference in the shape of one part from the original design.

JP 2003-237067 A JP 2002-240294 A

  However, the width of the shelf, that is, the distance between the edge of the first opening and the edge of the second opening along the connection surface is too large for the size of the opening width of the first opening. When the surface (meniscus) of the ink inside the nozzle hole is drawn toward the ink storage portion from the second opening, air that has entered the inside of the nozzle hole with the retreat of the ink surface is bubbled. As a result, it becomes easy to be taken into the ink. If bubbles are taken into the ink inside the nozzle hole, the pressure of the ink in the ink reservoir will not be properly transmitted to the ink inside the nozzle hole. There is a problem that leads to.

  An object of the present invention is to provide an ink jet recording apparatus capable of suppressing occurrence of ink ejection failure.

In order to achieve the above object, an invention of an ink jet recording apparatus according to claim 1 is provided.
An ink storage unit for storing ink,
A nozzle forming member provided with a nozzle hole communicating with the ink storage unit,
A pressure fluctuation unit that performs a pressure fluctuation operation that fluctuates the pressure of the ink in the ink storage unit according to the input drive signal;
A drive unit that outputs the drive signal for performing the pressure fluctuation operation of discharging the ink in the ink storage unit from the ink discharge port of the nozzle hole to the pressure fluctuation unit,
With
The nozzle hole includes a first portion having one end forming the ink ejection port, and a second portion connected to the other end of the first portion,
The first portion and the second portion each have a shape in which a distribution of a cross-sectional area in a cross section parallel to a nozzle surface formed by the ink ejection port becomes monotonically non-decreasing as the distance from the ink ejection port increases. The first opening of the first part in the connection surface of the first part and the second part extends along the nozzle axis direction perpendicular to the nozzle surface, and the first opening of the second part in the connection surface Connected with a shape and a positional relationship included in the second opening,
The drive unit supplies the drive signal for performing the pressure fluctuation operation of drawing the surface of the ink inside the nozzle hole toward the ink storage unit side from the second opening in the nozzle axis direction,
The opening width of the first opening in any direction passing through the center of the first opening along the connection surface is D, and the edge of the first opening along the direction of the opening width and the second When the maximum value of the distance between the edge of the opening is L,
0 <L ≦ 0.25D
Meet.

According to a second aspect of the present invention, in the inkjet recording apparatus according to the first aspect,
D and L are 0 <L <0.15D
Meet.

According to a third aspect of the present invention, in the inkjet recording apparatus according to the first or second aspect,
The first portion and the second portion may have an inner wall surface of the second portion in the nozzle forming member at an arbitrary cross-section passing through the center of the ink discharge port and parallel to the nozzle axis direction. The nozzle has a shape in which the minimum value of the angle formed between the inner wall surface of the first portion of the nozzle forming member and the maximum angle formed between the inner wall surface of the first portion and the nozzle axis direction.

According to a fourth aspect of the present invention, in the inkjet recording apparatus according to any one of the first to third aspects,
The first part comprises:
One end forms the ink ejection port, and a front portion in which an inner wall surface of the nozzle forming member extends from the ink ejection port in parallel to the nozzle axis direction,
A rear portion extending from the other end of the front portion to the first opening, wherein the cross-sectional area monotonically increases as the distance from the ink ejection port increases;
Having.

According to a fifth aspect of the present invention, in the inkjet recording apparatus according to the fourth aspect,
The length of the front portion in the nozzle axis direction is not more than 0.3 times the opening width of the ink discharge port in an arbitrary direction passing through the center of the ink discharge port and along the nozzle surface.

According to a sixth aspect of the present invention, in the inkjet recording apparatus according to any one of the first to fifth aspects,
The length of the first portion in the nozzle axis direction is 1.5 times or less the opening width of the ink discharge port in any direction passing through the center of the ink discharge port and along the nozzle surface.

According to a seventh aspect of the present invention, in the inkjet recording apparatus according to any one of the first to sixth aspects,
The nozzle forming member is composed of a single member.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that generation | occurrence | production of an ink discharge failure can be suppressed.

FIG. 2 is a diagram illustrating a schematic configuration of an inkjet recording apparatus. FIG. 3 is a diagram illustrating an internal configuration of a head unit. FIG. 2 is an exploded perspective view illustrating a configuration of a recording head. FIG. 2 is a block diagram illustrating a main functional configuration of the inkjet recording apparatus. FIG. 3 is a diagram illustrating a configuration of a nozzle hole provided in a nozzle plate, and is a cross-sectional view of the nozzle plate in an XZ plane. It is the top view which looked at the 1st opening and the 2nd opening from the Z direction. 9 is a graph showing an effect of suppressing bending of an ink ejection angle by providing a shelf portion. FIG. 4 is a diagram illustrating an example of a drive signal supplied for an ink ejection operation. FIG. 4 is a diagram illustrating an example of a drive signal supplied for an ink ejection operation. FIG. 4 is a schematic cross-sectional view illustrating an operation of the recording head according to a drive signal input. FIG. 4 is a schematic cross-sectional view illustrating an operation of the recording head according to a drive signal input. FIG. 4 is a schematic cross-sectional view illustrating an operation of the recording head according to a drive signal input. FIG. 7 is a diagram illustrating a meniscus of ink drawn toward a pressure chamber from a second opening. It is a figure showing the result of the simulation for confirming the effect of an embodiment. FIG. 4 is a schematic diagram illustrating a mode in which air bubbles are caught in ink in a nozzle hole. FIG. 4 is a schematic diagram illustrating a mode in which air bubbles are caught in ink in a nozzle hole. FIG. 4 is a schematic diagram illustrating a mode in which air bubbles are caught in ink in a nozzle hole. It is a figure explaining the formation method of a nozzle hole. It is a figure showing composition of a nozzle hole concerning a modification.

  Hereinafter, embodiments of the ink jet recording apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating a schematic configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention.
The inkjet recording device 1 includes a transport unit 10, a head unit 20, and the like.

The transport unit 10 includes a driving roller 101 that rotates about a rotation axis extending in the X direction in FIG. 1 and a ring-shaped transport belt 103 whose inside is supported by a driven roller 102. The transport unit 10 performs recording by rotating the drive roller 101 according to the operation of a transport motor (not shown) and rotating the transport belt 103 while the recording medium P is placed on the transport surface of the transport belt 103. The medium P is transported in the moving direction of the transport belt 103 (transport direction; Y direction in FIG. 1).
The recording medium P can be a sheet member such as paper or resin. The recording medium P is supplied onto the transport belt 103 by a paper supply device (not shown), and is discharged from the transport belt 103 to a predetermined paper discharge unit after ink is ejected from the head unit 20 and an image is recorded.

  The head unit 20 records an image on the recording medium P conveyed by the conveyance unit 10 by discharging ink at an appropriate timing based on the image data. In the ink jet recording apparatus 1 of the present embodiment, the four head units 20 corresponding to the four color inks of yellow (Y), magenta (M), cyan (C), and black (K) move in the transport direction of the recording medium P. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C and K colors from the upstream side. The number of head units 20 may be three or less or five or more.

FIG. 2 is a diagram showing the internal configuration of the head unit 20. FIG. 2 shows a configuration when the head unit 20 is viewed from the transport belt 103 side.
The head unit 20 has a plurality of recording heads 30 each provided with a plurality of nozzle holes 40 (nozzles) for discharging ink on an ink discharge surface facing the transport belt 103. In each recording head 30, a plurality of nozzle holes 40 are arranged in two rows along the X direction to form two nozzle rows, and these two nozzle rows are arranged at intervals of the nozzle holes 40 in the X direction. They are displaced from each other by one half. Further, in the head unit 20, the recording modules 30 are combined two by two to form a head module 30M, and the head modules 30M are arranged in a staggered lattice. In each head module 30M, the recording heads 30 are arranged in a positional relationship such that the nozzle holes 40 of the two recording heads 30 are alternately arranged in the X direction. With such an arrangement of the recording heads 30, the arrangement range of the nozzle holes 40 included in the head unit 20 in the X direction is changed in the X direction of the area on the recording medium P conveyed by the conveyance belt 103 where an image can be formed. It covers the width (recordable width). The head unit 20 is used in a fixed position during image recording, and sequentially discharges ink at predetermined intervals (intervals in the transport direction) at different positions in the transport direction according to the transport of the recording medium P. The image is recorded by the single pass method.

FIG. 3 is an exploded perspective view showing the configuration of the recording head 30. In FIG. 3, the number of nozzle rows in the recording head 30 is omitted and the number of nozzle holes 40 is omitted.
The recording head 30 has an ink ejection substrate 31 in which a plurality of pressure chambers 38 (ink storage sections) for storing ink are formed. A nozzle plate 33 provided with a plurality of nozzle holes 40 is bonded to an end surface of the ink discharge substrate 31. The nozzle hole 40 communicates with the pressure chamber 38 of the ink discharge substrate 31 so that the ink stored in the pressure chamber 38 is discharged. A cover plate 32 is attached to an upper portion of the ink discharge substrate 31 on the nozzle plate 33 side.
As the nozzle plate 33, a material that can be easily ablated by a laser beam, for example, a resin substrate such as polyimide, polyethylene terephthalate, polyamide, or polysulfone can be used. In the present embodiment, a nozzle plate 33 made of a polyimide substrate is used.

  The ink discharge substrate 31 has a structure in which two substrates 34 and 35 are bonded to each other via a bonding portion 36. The substrates 34 and 35 are made of a piezoelectric material such as lead zirconate titanate (PZT), and are polarized in opposite directions in the thickness direction. A plurality of pressure chambers 38 are formed on the ink discharge substrate 31 at equal intervals, and a partition 37 (piezoelectric element) made of a piezoelectric material is formed between the pressure chambers 38. An electrode 371 (FIGS. 8A to 8C) is provided on a side wall (the surface of the partition wall 37) of each pressure chamber 38, and the partition wall 37 responds to a voltage applied between the electrodes 371 of the adjacent pressure chamber 38. To bend (shear deformation) around the bonding portion 36. When a voltage signal having a predetermined drive waveform (hereinafter, referred to as a drive signal) is input to the electrode 371 from the head drive unit 39 (FIG. 4), the recording head 30 changes in the drive voltage in the drive signal. In response, the partition wall 37 undergoes shear deformation, thereby causing a pressure change in the pressure chamber 38 and ejecting ink from the nozzle holes 40. As described above, the recording head 30 of the present embodiment is in the shear mode (share mode) in which ink is ejected from the nozzle holes 40 by the shear (share) stress generated by applying an electric field in a direction orthogonal to the polarization direction of the piezoelectric element. This is an inkjet head having an ink ejection mechanism. In the present embodiment, in the recording head 30, a pressure fluctuation portion is configured by the partition wall 37 on which the electrode 371 is provided, and the shear deformation of the partition wall 37 according to the drive signal corresponds to the pressure fluctuation operation.

  Note that the configuration of the ink ejection mechanism in the recording head 30 is not limited to the above-described share mode. For example, a bend mode ink discharge mechanism using thin film vibration of the wall surface of a pressure chamber using piezo or an ink discharge mechanism of a method of discharging ink by heating ink to generate bubbles may be used.

FIG. 4 is a block diagram illustrating a main functional configuration of the inkjet recording apparatus 1.
The inkjet recording apparatus 1 includes a control unit 50, a head unit 20 having a head control unit 301 and a head drive unit 39, a transport drive unit 61, an input / output interface 62, a bus 63, and the like.

  The control unit 50 has a CPU 51 (Central Processing Unit), a RAM 52 (Random Access Memory), a ROM 53 (Read Only Memory), and a storage unit 54.

  The CPU 51 reads out various control programs and setting data stored in the ROM 53 and stores them in the RAM 52, and executes the programs to perform various arithmetic processes. Further, the CPU 51 controls the overall operation of the inkjet recording apparatus 1.

  The RAM 52 provides a working memory space to the CPU 51 and stores temporary data. The RAM 52 may include a non-volatile memory.

  The ROM 53 stores various control programs executed by the CPU 51, setting data, and the like. Note that a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used instead of the ROM 53.

  The storage unit 54 stores a print job (image recording command) input from the external device 2 via the input / output interface 62, image data related to the print job, and the like. For example, an HDD (Hard Disk Drive) is used as the storage unit 54, and a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The head control unit 301 outputs various control signals and image data to a head driving unit 39 provided in the recording head 30 at an appropriate timing according to a control signal from the control unit 50. Here, the control signal includes a signal that specifies a drive waveform related to a drive signal supplied from the head drive unit 39 to the partition wall 37 in the above-described ink ejection mechanism.
The head driving unit 39 supplies a driving signal to an electrode 371 provided on the partition wall 37 of the recording head 30 according to a control signal or image data input from the head control unit 301, so that the ink from the nozzle hole 40 is supplied. Is discharged. Specifically, the head driving section 39 has a waveform data storage section in which driving waveform data of a plurality of driving signals are stored, and one of the plurality of driving waveforms according to a control signal from the head control section 301 and image data. A drive waveform is selected and a drive signal is supplied to the electrode 371 of the partition 37.

  The transport drive unit 61 supplies a drive signal to a transport motor (not shown) based on a control signal supplied from the control unit 50 to rotate the drive roller 101, thereby moving the transport belt 103 around at a predetermined speed. .

  The input / output interface 62 transmits and receives data between the external device 2 and the control unit 50. The input / output interface 62 is configured by, for example, any one of various serial interfaces and various parallel interfaces, or a combination thereof.

  The bus 63 is a path for transmitting and receiving signals between the control unit 50 and other components.

  The external device 2 is, for example, a personal computer, and supplies a print job, image data, and the like to the control unit 50 via the input / output interface 62.

Next, the configuration of the nozzle holes 40 in the recording head 30 will be described in detail.
FIG. 5A and FIG. 5B are diagrams illustrating the configuration of the nozzle holes 40 provided in the nozzle plate 33. FIG.
FIG. 5A is a cross-sectional view of the nozzle plate 33 in the XZ plane. As shown in FIG. 5A, the nozzle hole 40 is configured by a through hole provided in the nozzle plate 33 made of a single member (polyimide substrate). The lower end of the nozzle hole 40 in FIG. 5A is an ink discharge port 40 a, and the upper end communicates with the pressure chamber 38. The nozzle hole 40 extends in a Z direction (nozzle axis direction) perpendicular to a surface (hereinafter, referred to as a nozzle surface) formed by the ink discharge ports 40a.

In the nozzle hole 40, the distribution of the cross-sectional area in a cross section parallel to the nozzle surface formed by the ink ejection port 40a (that is, a cross section perpendicular to the Z direction) is monotonically non-decreasing as the distance from the ink ejection port 40a increases (broadly monotonous) ), That is, in a shape in which there is no portion where the cross-sectional area decreases as the distance from the ink ejection port 40a increases. In addition, the nozzle hole 40 has a first portion 41 having one end forming the ink ejection port 40a, and a second portion connected to the other end of the first portion 41 (an end opposite to the ink ejection port 40a side). 42. In the present embodiment, the thickness of the nozzle plate 33 is 200 [μm], and the diameter d of the ink discharge port 40a is 20 [μm]. Further, the length A of the first portion 41 in the Z direction is desirably within a range that is 1.5 times or less the diameter d of the ink ejection port 40a, and the length A of the present embodiment is 15 μm. ].
Here, in the definition of the length A when the ink ejection port 40a has a shape other than a circle, the minimum value of the opening width passing through the area center of gravity (center) of the ink ejection port 40a is used instead of the diameter d. That is, the length A is within a range of 1.5 times or less the opening width of the ink ejection port 40a in any direction passing through the area center of gravity of the ink ejection port 40a and along the nozzle surface.
In FIG. 5A, the length of the second portion 42 (and the nozzle plate 33) in the Z direction is reduced so that the shape of the first portion 41 can be easily understood.

  The first portion 41 has a tapered shape such that the inner wall surface of the first portion 41 of the nozzle plate 33 forms an angle θ1 with the Z direction in a plane passing through the center of the ink discharge port 40a and parallel to the Z direction. have. Further, in a plane passing through the center of the ink ejection port 40a and parallel to the Z direction, the second portion 42 has an angle between the inner wall surface of the second portion 42 of the nozzle plate 33 and the Z direction that is larger than the angle θ1. It has a tapered shape that forms θ2. That is, the second portion 42 has a tapered shape having a larger inclination angle than the first portion 41. In the present embodiment, the angle θ1 is about 4 degrees, and the angle θ2 is about 36 degrees. In FIG. 5A, the angle of the inner wall surface in the XZ plane is shown. However, in any other cross section that passes through the center of the ink ejection port 40a and is parallel to the Z direction, the second portion 42 is not the first portion. It has a tapered shape having a larger inclination angle than 41.

  The first portion 41 and the second portion 42 are connected at a connection surface S parallel to the nozzle surface. In the first portion 41 and the second portion 42, the first opening 41a of the first portion 41 on the connection surface S is included in the range of the second opening 42a of the second portion 42 on the connection surface S. They are connected with a shape and positional relationship. Thus, a shelf-shaped step is formed on the connection surface S, and a shelf-shaped portion T (terrace portion) is provided.

FIG. 5B is a plan view of the first opening 41a and the second opening 42a as viewed from the Z direction. As shown in FIG. 5B, the edge of the first opening 41a has a circular shape, and the edge of the second opening 42a has a square shape with four rounded vertices. The region between the edge of the first opening 41a and the edge of the second opening 42a forms a shelf T. This shelf T is in the plane of the connection surface S and is therefore parallel to the nozzle surface.
In the following, the opening width of the first opening 41a (the diameter of a circle formed by the first opening 41a in the present embodiment) in the direction along the connection surface S passing through the center of the first opening 41a is D (hereinafter, referred to as D). In this case, the maximum value of the distance between the edge of the first opening 41a and the edge of the second opening 42a along the direction of the opening width is represented by L (hereinafter, referred to as a shelf-like portion). T width L).

  The nozzle hole 40 of the present embodiment is provided with the shelf portion T, so that when an error occurs in the formation positions of the first portion 41 and the second portion 42, the shape of the first portion 41 is hardly affected. Has become. That is, if the relative displacement of the first portion 41 and the second portion 42 in the XY plane is within the width of the shelf T, the shape of the shelf T fluctuates, but the first opening Since the state where 41a is included in the second opening 42a on the connection surface S is maintained, the shape itself of the first portion 41 is not affected. As described above, since the shape of the first portion 41 is not easily changed, the bending of the ejection angle of the ink ejected from the nozzle hole 40 when the formation positions of the first portion 41 and the second portion 42 are shifted. It can be made hard to occur.

FIG. 6 is a graph showing the effect of suppressing the bending of the ink ejection angle by providing the shelf portion T.
Curves C1, C2, and C3 in FIG. 6 respectively show the case where the shelf-shaped portion T is not provided in the nozzle hole 40, the case where the shelf-shaped portion T whose width L is equal to 2 [μm] is provided, and the width L 6 shows the amount of bending of the ink ejection angle with respect to the relative displacement between the first portion 41 and the second portion 42 in each case where a shelf-shaped portion T having a uniform thickness of 6 [μm] is provided.

  As shown by the curve C1 in FIG. 6, when the shelf-shaped portion T is not provided, the bending amount of the ink ejection angle sharply increases according to the relative displacement between the first portion 41 and the second portion 42. I will do it. This is because, when the shelf-shaped portion T is not provided, if a positional shift occurs between the first portion 41 and the second portion 42, the connection surface between the first portion 41 and the second portion 42 is located on the nozzle surface. This is because the direction in which ink flows into the first portion 41 includes components other than the Z direction.

  On the other hand, as shown by the curves C2 and C3 in FIG. 6, when the shelf portion T is provided, the bending amount of the ink ejection angle with respect to the relative displacement amount of the first portion 41 and the second portion 42. Is greatly reduced. This is because, as described above, the positional shift between the first portion 41 and the second portion 42 is absorbed by the change in the shape of the shelf portion T, and the connection surface S becomes parallel to the nozzle surface. This is because the state is easily maintained. The effect of reducing the bending of the ink ejection angle increases as the width L of the shelf T increases.

  Next, the ink ejection operation of the recording head 30 according to the drive signal in the ink jet recording apparatus 1 of the present embodiment and the behavior of the ink in the nozzle holes 40 in the ink ejection operation will be described.

FIGS. 7A and 7B are diagrams each showing an example of a drive signal supplied from the head drive unit 39 to the electrode 371 of the partition wall 37 for an ink discharging operation.
8A, 8B, and 8C are schematic cross-sectional views illustrating the operation of the recording head 30 in response to the input of the drive signal, and show a cross section of the recording head 30 in a plane parallel to the nozzle plate 33. 8A, 8B, and 8C illustrate three adjacent pressure chambers 38A to 38C. Hereinafter, the operation when ink is ejected from the central pressure chamber 38B will be described. FIG. 8A shows a neutral state in which the electrodes 371A, 371B, and 371C are set to the ground potential.

The drive signal shown in FIG. 7A has an expansion pulse p1 of voltage V1 applied from time t0 to time t1. Here, the application time (t1−t0) of the expansion pulse p1 is set to の of the resonance period corresponding to the acoustic natural frequency of the pressure wave in the pressure chamber 38.
When the supply of the drive signal of FIG. 7A to the electrode 371 is started, the voltage V1 is supplied to the electrode 371B in response to the application of the expansion pulse p1, and the electrodes 371A and 371C are connected to the ground potential, as shown in FIG. 8B. Accordingly, the partition 37 sandwiching the pressure chamber 38B is sheared and deformed, and the volume of the pressure chamber 38B expands. Thereby, the pressure of the ink in the pressure chamber 38 decreases. When the application of the expansion pulse p1 is completed at time t1 and the electrodes 371A, 371B, and 371C are set to the ground potential, the state of FIG. 8B transitions to the state of FIG. 8A, and the volume of the pressure chamber 38 is reduced. It contracts and the pressure of the ink in the pressure chamber 38 increases. The ink is ejected from the ink ejection port 40a of the nozzle hole 40 by the pressure of the ink.
As described above, according to the drive signal in FIG. 7A, a series of operations (pressure fluctuation operation) of the partition 37 that increases the pressure of the ink in the pressure chamber 38 after decreasing the pressure is performed. Is ejected from the nozzle hole 40.

The drive signal shown in FIG. 7B includes an expansion pulse p1 of the voltage V1 applied from time t0 to time t1, and a contraction pulse p2 of voltage −V2 applied from time t1 to time t2. Here, the application time (t2−t1) of the contraction pulse p2 is twice as long as the application time of the expansion pulse p1, and the absolute value of the voltage −V2 is の of the absolute value of the voltage V1.
When the drive signal shown in FIG. 7B is supplied to the partition 37, the partition 37 is deformed in a direction in which the volume of the pressure chamber 38 expands in response to the rise of the expansion pulse p1, as shown in FIG. Ink pressure decreases. Then, when the application of the contraction pulse p2 is started, as shown in FIG. 8C, the voltage -V2 is supplied to the electrode 371B, and the electrodes 371A and 371C are set to the ground potential. 37 undergoes shear deformation, and the volume of the pressure chamber 38B further contracts from the neutral state in FIG. 8A. Accordingly, the pressure of the ink in the pressure chamber 38 increases, and the ink is discharged from the ink discharge port 40a of the nozzle hole 40 by the pressure of the ink.
As described above, even with the drive signal in FIG. 7B, a series of operations (pressure fluctuation operation) of the partition wall 37 for increasing and decreasing the pressure of the ink in the pressure chamber 38 is performed. Ink is ejected from the nozzle holes 40.

  More specifically, when the pressure fluctuation operation of the partition wall 37 is started by the application of the drive signal of FIG. 7A or 7B, first, in response to a decrease in the pressure of the ink in the pressure chamber 38 due to the application of the expansion pulse p1, The surface (meniscus) of the ink in the nozzle hole 40 is drawn toward the pressure chamber 38 and recedes. When the pressure of the ink in the pressure chamber 38 increases by the end of the application of the expansion pulse p1 in the drive signal of FIG. 7A and by the start of the application of the contraction pulse p2 in the drive signal of FIG. 7B, the nozzle holes 40 are correspondingly increased. The meniscus of the ink inside is pushed toward the ink ejection port 40a in the Z direction, and a part of the ink is ejected from the ink ejection port 40a as ink droplets. Note that the behavior of the meniscus of the ink is not always in synchronization with the application period of the pulse in the drive signal, and the inertia according to the ink flow that has already occurred before the application of the pulse, and the behavior within the nozzle hole 40. Can move in the Z direction before and after the application of each pulse according to the pressure distribution and the like.

  Here, in the inkjet recording apparatus 1 of the present embodiment, in the series of behaviors of the meniscus of the ink in the above-described ink ejection operation, the position in the Z direction of the meniscus when the meniscus is drawn into the pressure chamber 38 side is: The second portion 42 is retracted from the second opening 42a to the pressure chamber 38 side. In other words, a drive signal that causes the meniscus of the ink in the nozzle hole 40 to be drawn toward the pressure chamber 38 from the second opening 42a in the Z direction in accordance with the pressure fluctuation operation of the partition 37 is used for ink ejection. ing.

FIG. 9 is a diagram illustrating the meniscus M of the ink In drawn into the pressure chamber 38 from the second opening 42a.
When the meniscus M of the ink In is drawn closer to the pressure chamber 38 than the second opening 42a, the range where the meniscus M can exist is expanded to the inside of the second portion 42, so that the meniscus M is easily spread. For this reason, the meniscus M enters the second portion 42 deeply unless an appropriate ink pressure is applied to push the meniscus M toward the ink ejection port 40a against the meniscus M entering the inside of the second portion 42. . As a result, a problem occurs in which the meniscus M entrains bubbles and the bubbles are taken into the ink In. If air bubbles are trapped in the ink In, the pressure of the ink in the pressure chamber 38 will not be properly transmitted to the ink In in the nozzle hole 40, and an abnormality related to the amount of ink to be ejected and the direction of ink ejection will occur, resulting in defective ink ejection. Leads to.

On the other hand, in the nozzle hole 40 of the present embodiment, the nozzle hole 40 is formed such that the opening width D of the first opening 41a and the width L of the shelf portion T satisfy the following expression (1). Thus, the occurrence of the above-described inconvenience is suppressed.
0 <L ≦ 0.25D (1)
For example, the opening width D of the first opening 41a in the direction parallel to the X direction shown in FIG. 5A is 21 [μm], and the opening width W of the second opening 42a is 25 [μm]. Has a width L of 2 μm. Although not shown in FIG. 5A, the opening width D and the width L of the shelf-shaped portion T satisfy the above equation (1) in an arbitrary direction passing through the center of the first opening 41a.

  By limiting the upper limit of the width L of the shelf portion T as in equation (1), the position of the portion of the inner wall surface of the first portion 41 that is connected to the shelf portion T and the position of the inner wall surface of the second portion 42 are determined. The position of the portion connected to the shelf T can be prevented from being extremely separated in the direction along the connection surface S. This suppresses a rapid expansion of the expandable range of the meniscus M that has entered the inside of the second portion 42 from the first portion 41. By suppressing the expandable range of the meniscus M, the pressure exerted on the meniscus M from the ink In is less likely to be dispersed, and a reduction in the pressure received by each part of the meniscus M from the ink In is suppressed. In particular, the pressure of the ink In along the inner wall surface of the second portion 42 can be easily applied to the meniscus M that has entered the inside of the second portion 42, as shown by the arrow in FIG. . As a result, it is possible to prevent the meniscus M from penetrating deeply into the second portion 42 and entraining the air bubbles, thereby preventing the air bubbles from being taken into the ink In.

Further, instead of the above equation (1), the nozzle hole 40 is formed so that the opening width D of the first opening 41a and the width L of the shelf-shaped portion T satisfy the following equation (2). Thus, the occurrence of the above-described inconvenience is more reliably suppressed.
0 <L <0.15D (2)

  In the present embodiment, an example in which the first opening 41a in the first portion 41 is circular is used. However, the shape of the first opening 41a is not limited to this, and may be, for example, an ellipse or a polygon (the vertex is (Including those having roundness). When the first opening 41a has a shape other than a circle, D and L in Equations (1) and (2) are calculated along a direction passing through the area center of gravity (center) of the first opening 41a. Further, when the widths of the pair of shelf portions T in one direction are different from each other, the larger one (maximum value) of the widths of the pair of shelf portions T is set to L.

Next, a result of a simulation performed to confirm the effect of the present embodiment will be described.
FIG. 10 is a diagram showing a result of a simulation for confirming the effect of the present embodiment. Here, in the nozzle hole 40 shown in FIG. 5A where the opening width D of the first opening 41a is 21 [μm], the width L of the shelf portion T is set in seven steps from 0 [μm] to 10 [μm]. The behavior of the ink in the nozzle hole 40 when changing to was analyzed by fluid simulation. In the simulation, the presence or absence of bubbles when the meniscus M is drawn to the pressure chamber 38 side in the second portion 42 of the nozzle hole 40 in the ink ejection operation was analyzed. In FIG. 10, the analysis results of the entrapment of bubbles are indicated by “、”, “、”, and “×”.

FIGS. 11A, 11B, and 11C are schematic diagrams illustrating a mode in which bubbles are caught in the ink in the nozzle holes 40. FIG.
FIG. 11A shows an example where the meniscus M of the ink In is stably held in the second portion 41 and there is no entrapment of bubbles. In FIG. 10, the case where such an analysis result is obtained is indicated by “で”.
FIG. 11B shows an example in which the meniscus M is retained in the second portion 41, but becomes unstable with a certain probability and air bubbles may be involved. In FIG. 10, the case where such an analysis result is obtained is indicated by “で”.
FIG. 11C shows an example in which the meniscus M is crushed (broken) in the second portion 41 and entrainment of air bubbles occurs. In FIG. 10, the case where such an analysis result is obtained is indicated by “x”.

As shown in FIG. 10, when the ratio (L / D) of the width L of the shelf portion T to the opening width D of the first opening 41a exceeds 0.25, the meniscus M is crushed and bubbles are trapped. A result ("x") was obtained.
On the other hand, within the range where L / D is 0.25 or less, the analysis result of the entrapment of the bubble is “で” or “「 ”, and the meniscus M is held in the second portion 41 to keep the entrainment of the bubble constant. It turned out that it can be suppressed within the range of about.
In particular, when the L / D was less than 0.15, the result was that the meniscus M was stably held in the second portion 41 and no bubbles were trapped (“○”).

  From these results, by forming the nozzle hole 40 so that the opening width D of the first opening 41a and the width L of the shelf portion T satisfy the above expression (1), the ink in the nozzle hole 40 is formed. It has been confirmed that the entrapment of air bubbles into the nozzle can be suppressed within a certain range, and furthermore, by forming the nozzle holes 40 so as to satisfy the expression (2), the entrapment of air bubbles can be more reliably suppressed. Was.

Next, a method for forming the nozzle hole 40 will be described.
The nozzle hole 40 having the above-described configuration is not particularly limited, but can be formed by, for example, the following method.

FIG. 12 is a diagram illustrating a method of forming the nozzle holes 40.
In the method of forming the nozzle holes 40 in FIG. 12, first, the nozzle plate 33 made of a polyimide substrate having a thickness of 200 [μm] is formed through a mask 70 having a transmission hole having a size corresponding to the opening shape of the ink discharge port 40a. By irradiating a laser (here, an excimer laser), a through-hole penetrating the nozzle plate 33 is formed (S1 in FIG. 12). As a result, the ink discharge ports 40a are formed in the nozzle plate 33. Here, by adjusting the energy density of the laser, a through hole having a tapered shape can be formed from the opening on the inlet side of the laser to the opening on the outlet side (ink ejection port 40a).
Next, a mask 70 having a transmission hole having a size corresponding to the opening shape of the second opening 42a is arranged at a position where the transmission hole is concentric with the opening of the ink discharge port 40a, and the mask 70 is inserted through the mask 70. The nozzle plate 33 is irradiated with a laser to pierce it to a depth of 185 [μm]. Thus, the shape of the first portion 41 is determined, and the shelf T is formed (S2 in FIG. 12).
After that, by irradiating laser while changing the area of the transmission hole of the mask 70 to the opening shape of the second portion 42 on the pressure chamber 38 side, the inner wall surface of the second portion 42 is processed into a tapered shape ( S3 in FIG. 12).
In the step shown in S3 of FIG. 12, the inner wall surface may be processed into a tapered shape by sequentially applying a plurality of masks 70 having different opening shapes and irradiating a laser. Also, at the time of forming the through hole in S1 in FIG. 12, the tapered shape may be processed in the same manner as in S3 in FIG. In the above description, the second portion 42 is formed after the first portion 42 is formed, but the second portion 42 may be formed first. Further, instead of the above method, the first portion 41 and the second portion 42 may be formed by punching with a conical or quadrangular pyramid punch.

  In such a forming method, a problem may occur in which the axis of the transmission hole of the mask 70 in S1 of FIG. 12 and the axis of the transmission hole of the mask 70 in S2 of FIG. 12 are displaced, but the nozzle hole 40 has the shelf portion T. With this configuration, even if the axis deviation occurs, the connection surface S of the first portion 41 and the second portion 42 is maintained in a state parallel to the nozzle surface, and the shape of the first portion 41 is not easily changed. It is possible to suppress the occurrence of the problem that the ink ejection direction is deflected.

When a bend mode ink ejection mechanism is used in the recording head 30, a silicon substrate is suitably used as the nozzle plate 33. When a silicon substrate is used, the nozzle holes 40 can be formed by, for example, the following method.
That is, first, a photoresist is applied to one surface of a 200 [μm] -thick silicon substrate having a thermal oxide film formed on both front and back surfaces, and the opening shape of the second portion 42 on the pressure chamber 38 side is formed by photolithography. A photoresist pattern corresponding to is formed. By etching the thermal oxide film using the photoresist pattern, an etching mask pattern using the thermal oxide film is formed. Then, using the etching mask pattern, the silicon substrate is etched to a depth of 185 [μm] by anisotropic dry etching to form the second portion 42.
Next, a photoresist is applied to the other surface of the silicon substrate, and a photoresist pattern corresponding to the opening shape of the ink discharge port 40a is formed by photolithography at a position concentric with the opening of the second portion 42. I do. By etching the thermal oxide film using the photoresist pattern, an etching mask pattern using the thermal oxide film is formed. Then, using the etching mask pattern, the first portion 41 is formed by etching the silicon substrate by anisotropic dry etching until the silicon substrate penetrates the second portion 42.
As a silicon substrate used in this method, a silicon substrate in which a silicon oxide film as an etching stopper is laminated at a boundary position between the first portion 41 and the second portion 42 may be used. Thereby, the etching depth for forming the second portion 42 can be accurately controlled. Further, the nozzle holes 40 may be formed by wet etching instead of dry etching.

(Modification)
Subsequently, a modified example of the above embodiment will be described. In the present modification, the shape of the first portion 41 in the nozzle hole 40 is different from the above embodiment. Hereinafter, differences from the above embodiment will be described.

FIG. 13 is a diagram illustrating the configuration of the nozzle hole 40 according to the present modification.
One end of the nozzle hole 40 of this modified example forms an ink discharge port 40a, and the inner wall surface of the nozzle plate 33 extends straight from the ink discharge port 40a in the Z direction in a straight portion 411 (tip portion); A tapered portion 412 (rear end portion) extending from the other end of 411 to the first opening 41a and having a monotonically increasing cross-sectional area (that is, an inner wall surface having a tapered shape) as the distance from the ink ejection port 40a increases. Have. The inclination angle of the inner wall surface of the tapered portion 412 from the Z direction is smaller than the inclination angle of the inner wall surface of the second portion 42 from the Z direction.
Further, it is desirable that the length A1 of the straight portion 411 in the Z direction be within a range of 0.3 times or less the diameter d of the ink discharge port 40a, and the length A1 of the present embodiment is 5 μm ].
Note that, in the definition of the length A1 when the ink ejection port 40a is not circular, the minimum value of the opening width passing through the area center of gravity (predetermined center) of the ink ejection port 40a is used instead of the diameter d. That is, the length A1 is within a range of 0.3 times or less the opening width of the ink discharge port 40a in any direction passing through the area center of gravity of the ink discharge port 40a and along the nozzle surface.

In this manner, by providing the straight portion 411 at the tip of the first portion 41 on the side of the ink ejection port 40a, the ink immediately before being ejected from the ink ejection port 40a moves along the straight portion 411. The occurrence of the problem that the angle is bent is suppressed.
Note that the second portion 42 may also be configured to include two or more portions having different inclination angles of the inner wall surface from the Z direction. In this case, the nozzle hole 40 may be formed such that the minimum value of the inclination angle of the inner wall surface of the second portion 42 is larger than the maximum value of the inclination angle of the inner wall surface of the first portion 41.

As described above, the ink jet recording apparatus 1 according to the present embodiment includes the pressure chamber 38 for storing the ink, the nozzle plate 33 provided with the nozzle hole 40 communicating with the pressure chamber 38, and the A partition 37 for performing a pressure fluctuation operation for fluctuating the pressure of the ink in the pressure chamber 38 and a driving signal for performing a pressure fluctuation operation for discharging the ink in the pressure chamber 38 from the ink discharge port 40 a of the nozzle hole 40. And a head drive unit 39 that outputs the ink to the nozzle hole 40. The nozzle hole 40 includes a first portion 41 having one end forming an ink discharge port 40a, and a second portion 42 connected to the other end of the first portion 41. The first portion 41 and the second portion 42 are arranged such that the distribution of the cross-sectional area in a cross section parallel to the nozzle surface formed by the ink ejection port 40a is simply increased as the distance from the ink ejection port 40a increases. It has a non-decreasing shape and extends along the Z direction (nozzle axis direction) perpendicular to the nozzle surface, and the first portion 41 of the first portion 41 at the connection surface S of the first portion 41 and the second portion 42. The opening 41a is connected with a shape and a positional relationship included in the second opening 42a of the second portion 42 on the connection surface S to form a shelf-shaped portion T, and the head driving portion 39 Supplies a drive signal for causing the partition wall 37 to perform a pressure fluctuation operation of drawing the surface of the ink inside the nozzle hole 40 toward the pressure chamber 38 from the second opening 42a in the Z direction, and the center of the first opening 41a. , The opening width of the first opening 41a in any direction along the connection surface S is defined as D, between the edge of the first opening 41a and the edge of the second opening 42a along the direction of the opening width. When the maximum value of the distance is L,
0 <L ≦ 0.25D (1)
Meet.
By limiting the upper limit of the width L of the shelf portion T in this manner, the position of the inner wall surface of the first portion 41 connected to the connection surface S and the position of the inner wall surface of the second portion 42 extend along the connection surface S. It can be prevented from being extremely separated in the direction. This suppresses a rapid expansion of the expandable range of the meniscus M that has entered the inside of the second portion 42 from the first portion 41. By suppressing the expandable range of the meniscus M, the pressure exerted on the meniscus M from the ink is less likely to be dispersed, and it is possible to suppress a reduction in the pressure that each part of the meniscus M receives from the ink. In particular, the pressure of the ink along the inner wall surface of the second portion 42 is likely to be applied to the meniscus M that has entered the inside of the second portion 42, so that the shape of the meniscus M can be easily maintained. As a result, it is possible to prevent the meniscus M from penetrating deeply into the second portion 42 and entraining the air bubbles, thereby preventing the air bubbles from being taken into the ink.
Further, by providing the shelf portion T in the nozzle hole 40, when an error occurs in the formation position of the first portion 41 and the second portion 42, occurrence of a problem that affects the shape of the first portion 41 can be prevented. Can be suppressed. That is, if the relative displacement of the first portion 41 and the second portion 42 in the XY plane is within the range of the width of the shelf T, the shape of the shelf T fluctuates. Since the connection surface S of the portion 41 and the second portion 42 is maintained in a state parallel to the nozzle surface, the shape itself of the first portion 41 is not affected. Accordingly, when the formation positions of the first portion 41 and the second portion 42 are displaced from each other, a change in the shape of the first portion 41 from the initial design can be suppressed. The bending of the injection angle can be made hard to occur.

Further, the opening width D of the first opening 41a and the width L of the shelf portion T are 0 <L <0.15D (2)
By providing the nozzle hole 40 so as to satisfy the condition, it is possible to more reliably suppress the occurrence of a problem in which bubbles are trapped and taken in the ink in the nozzle hole 40.

  Further, the first portion 41 and the second portion 42 have an inner wall surface between the Z direction and the inner wall surface of the second portion 42 of the nozzle plate 33 at an arbitrary cross section passing through the center of the ink ejection port 40a and parallel to the Z direction. It has a shape in which the minimum value of the angle is larger than the maximum value of the angle formed between the inner wall surface of the first portion 41 of the nozzle plate 33 and the Z direction. With such a configuration, it is possible to efficiently discharge the ink by reducing the drag (viscous resistance) that the ink traveling in the Z direction in the nozzle hole 40 receives from the wall surface of the nozzle hole 40. Therefore, the ink ejection operation can be performed by the drive signal including the pulse having the smaller voltage amplitude. Further, in such a configuration, when the meniscus M of the ink enters the inside of the second portion 42 of the nozzle hole 40, the meniscus M easily spreads, but the nozzle hole 40 is formed by the above formula (1) or ( By being formed so as to satisfy 2), the shape of the meniscus M can be easily maintained. Therefore, it is possible to effectively suppress the occurrence of a defect taken into the ink.

  Further, the first portion 41 of the modified example has a straight portion 411 in which one end forms an ink ejection port 40a, and an inner wall surface of the nozzle plate 33 extends from the ink ejection port 40a in parallel in the Z direction. A tapered portion 412 extending from the other end to the first opening 41a and having a monotonically increasing cross-sectional area as the distance from the ink ejection port 40a increases. Accordingly, since the ink immediately before being ejected from the ink ejection port 40a moves along the straight portion 411, it is possible to more reliably suppress the occurrence of the problem that the ejection angle of the ink is bent.

  In addition, the length of the straight portion 411 in the Z direction is equal to 0 of the opening width (the diameter d in the above embodiment) of the ink discharge port 40a in any direction passing through the center of the ink discharge port 40a and along the nozzle surface. .3 times or less. Since the straight portion 411 is a narrow path having the same diameter as the ink ejection port 40a which is narrowly provided for ejecting minute ink droplets, the ink passing through the straight portion 411 is affected by the drag received from the wall surface. However, by limiting the length of the straight portion 411 to the above range, the effect of the drag can be suppressed and ink can be ejected efficiently.

  The length of the first portion 41 in the Z direction is the opening width (the diameter d in the above embodiment) of the ink discharge port 40a in any direction passing through the center of the ink discharge port 40a and along the nozzle surface. 1.5 times or less. The first portion 41 has a smaller cross-sectional area than the second portion 42, and the ink passing through the first portion 41 is more susceptible to the drag received from the wall surface than the second portion 42. By limiting the length within the above range, the effect of the drag can be suppressed and ink can be ejected efficiently.

  Further, the nozzle plate 33 of the present embodiment is formed of a single member. In the configuration in which the plate on which the first portion 41 is formed and the plate on which the second portion 42 is formed are bonded with an adhesive, there is a problem that the adhesive may enter the position of the shelf T in the nozzle hole 40. By configuring the nozzle plate 33 by a single member as described above, such a problem can be prevented. As a result, it is possible to suppress the occurrence of abnormalities in the ink ejection amount and the flying direction due to the influence of the adhesive.

Note that the present invention is not limited to the above-described embodiment and modifications, and various modifications are possible.
For example, the drive signal supplied for the ink ejection operation is not limited to those shown in FIGS. 7A and 7B, and the drive signal in the nozzle hole 40 is changed in accordance with a change in the ink pressure in the pressure chamber 38 due to the application of the drive signal. Any drive signal that causes the meniscus of the ink to be drawn toward the pressure chamber 38 from the second opening 42a can be used. For example, the driving signal may be a combination of at least one of the expansion pulse and the contraction pulse.

  Further, the shapes of the first portion 41 and the second portion 42 in the nozzle hole 40 are not limited to those described in the above-described embodiment and modified examples. For example, the inner wall surface of at least one of the first portion 41 and the second portion 42 may have a straight shape parallel to the Z direction. Further, the inner wall surface of at least one of the first portion 41 and the second portion 42 may have a step or unevenness.

  In the above embodiment, the single-pass type inkjet recording apparatus 1 has been described as an example. However, the present invention may be applied to an inkjet recording apparatus that records an image while scanning a recording head.

  Although some embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and equivalents thereof .

  INDUSTRIAL APPLICATION This invention can be utilized for an inkjet recording device.

REFERENCE SIGNS LIST 1 inkjet recording device 2 external device 10 transport unit 101 drive roller 102 driven roller 103 transport belt 20 head unit 30 recording head 30M head module 301 head control unit 31 ink ejection substrate 32 cover plate 33 nozzle plate 34, 35 substrate 36 bonding unit 37 Partition 371, 371A, 371B, 371C Electrode 38, 38A, 38B, 38C Pressure chamber 39 Head drive unit 40 Nozzle 40a Ink ejection port 41 First part 41a First opening 411 Straight part 412 Tapered part 42 Second part 42a Second Opening 50 control unit 51 CPU
52 RAM
53 ROM
54 storage unit 61 transport drive unit 62 input / output interface 63 bus 70 mask In ink M meniscus P recording medium T shelf

Claims (7)

An ink storage unit for storing ink,
A nozzle forming member provided with a nozzle hole communicating with the ink storage unit,
A pressure fluctuation unit that performs a pressure fluctuation operation that fluctuates the pressure of the ink in the ink storage unit according to the input drive signal;
A drive unit that outputs the drive signal for performing the pressure fluctuation operation of discharging the ink in the ink storage unit from the ink discharge port of the nozzle hole to the pressure fluctuation unit,
With
The nozzle hole includes a first portion having one end forming the ink ejection port, and a second portion connected to the other end of the first portion,
The first portion and the second portion each have a shape in which a distribution of a cross-sectional area in a cross section parallel to a nozzle surface formed by the ink ejection port becomes monotonically non-decreasing as the distance from the ink ejection port increases. The first opening of the first part in the connection surface of the first part and the second part extends along the nozzle axis direction perpendicular to the nozzle surface, and the first opening of the second part in the connection surface Connected with a shape and a positional relationship included in the second opening,
The drive unit supplies the drive signal for performing the pressure fluctuation operation of drawing the surface of the ink inside the nozzle hole toward the ink storage unit side from the second opening in the nozzle axis direction,
The opening width of the first opening in any direction passing through the center of the first opening along the connection surface is D, and the edge of the first opening along the direction of the opening width and the second When the maximum value of the distance between the edge of the opening is L,
0 <L ≦ 0.25D
Inkjet recording device that satisfies D and L are 0 <L <0.15D
2. The ink jet recording apparatus according to claim 1, wherein the following conditions are satisfied.   The first portion and the second portion may have an inner wall surface of the second portion in the nozzle forming member at an arbitrary cross-section passing through the center of the ink discharge port and parallel to the nozzle axis direction. 3. The nozzle according to claim 1, wherein the minimum value of the angle formed between the nozzle forming member and the inner wall surface of the first portion is larger than the maximum value of the angle formed between the inner wall surface and the nozzle axis direction. 4. Ink jet recording device. The first part comprises:
One end forms the ink ejection port, and a front portion in which an inner wall surface of the nozzle forming member extends from the ink ejection port in parallel to the nozzle axis direction,
A rear portion extending from the other end of the front portion to the first opening, wherein the cross-sectional area monotonically increases as the distance from the ink ejection port increases;
The inkjet recording apparatus according to claim 1, further comprising:   The length of the front portion in the nozzle axis direction is not more than 0.3 times the opening width of the ink ejection port in any direction passing through the center of the ink ejection port and along the nozzle surface. 5. The ink jet recording apparatus according to 4.   The length of the first portion in the nozzle axis direction is 1.5 times or less the opening width of the ink ejection port in an arbitrary direction passing through the center of the ink ejection port and along the nozzle surface. Item 6. The ink jet recording apparatus according to any one of items 1 to 5.   The inkjet recording apparatus according to claim 1, wherein the nozzle forming member is a single member.

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