JP2004249470A - Inkjet recording head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inkjet recording head in which acoustic resistance of an ink supply passage is increased without increasing inertance, and the ink supply passage is imparted with strength sufficient for preventing deformation in the manufacturing process. <P>SOLUTION: The inkjet recording head is shaped to increase acoustic resistance without increasing inertance because the shape of the ink supply passage 18 has a significant effect on the ink drop ejection efficiency and the damping time of meniscus. Consequently, the groove-like ink supply passage 18 has a rectangular cross-section of height H (about 30 μm) and width D (about 140 μm) and has length L (about 320 μm). Precision of the height H influences most on the acoustic resistance and inertance but it can be machined with high precision because the height H is the thickness of an ink supply plate 30. On the contrary, the width D and length L of the ink supply passage 18 cannot be machined with high precision because it is bored by etching, but since the width D and length L are large, machining precision thereof does not influence significantly on the acoustic resistance and inertance and does not cause a problem. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink supply path of an ink jet recording head and an ink jet recording apparatus.
[0002]
[Prior art]
2. Description of the Related Art There is known an ink jet recording method in which a pressure chamber filled with ink is pressurized through a vibration plate by using an electrostrictive action of a piezoelectric element to discharge ink droplets from a nozzle communicating with the pressure chamber.
[0003]
In such an ink jet recording head, the ink introduced from the ink supply port is filled in the common ink chamber, and the pressure chamber is filled from the common ink chamber through the ink supply path.
[0004]
The shape of the ink supply path affects the ink ejection efficiency and the meniscus decay time. That is, in order to make it difficult for ink to flow backward from the pressure chamber to the common ink chamber and to efficiently eject ink droplets from the nozzles, it is desired to increase the acoustic resistance of the ink supply path. However, if the acoustic resistance is increased, the inertance of the ink supply path is also increased, so that the meniscus becomes difficult to stabilize after the ink droplet is ejected from the nozzle. Therefore, a design that balances acoustic resistance and inertance is important. In other words, it is desired that the shape be such that the acoustic resistance is large and the inertance is not so large.
[0005]
Conventionally, for an ink supply path having such characteristics, a groove-shaped ink supply path formed by etching or the like in the horizontal direction with respect to the diaphragm, or a press working or an electroforming processing in the vertical direction with respect to the diaphragm. There is a supply path in the shape of a hole formed by the above method. (For example, see Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, and Patent Literature 5)
[0006]
[Patent Document 1]
JP 07-329292 A
[Patent Document 2]
Japanese Patent Publication No. 10-508808
[Patent Document 3]
JP 08-108534 A
[Patent Document 4]
JP-A-08-169111
[Patent Document 5]
JP-A-09-150511
[0007]
[Problems to be solved by the invention]
However, the ink supply path formed in this way is difficult to achieve accuracy, the manufacturing cost is high, or in the case of electroforming, the ink supply path is easily corroded by ink. There was a problem.
[0008]
Further, in the case of a groove-shaped ink supply path located in the horizontal direction (directly below) with respect to the diaphragm, the strength is low because the upper surface of the supply path is a thin diaphragm. Therefore, when the electrical connection portion of the piezoelectric element must be located on the upper surface of the ink supply path due to the increase in the density of the nozzles, pressure is applied at the time of electrical connection and the ink supply path is deformed. Could be damaged.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an ink supply path having a large acoustic resistance, a large inertance, and a sufficient strength not to deform the ink supply path in a manufacturing process. And
[0010]
[Means for Solving the Problems]
The ink jet recording head according to the first aspect of the present invention includes an ink supply path that communicates an opening of the common ink chamber with the pressure chamber, and supplies ink from the common ink chamber to the pressure chamber. In an ink jet recording head that pressurizes ink in a pressure chamber and ejects ink droplets from a nozzle, the ink supply path is formed without including a pressure generating surface of the pressure chamber in contact with the actuator, and The ink flow direction in the path is parallel to the pressure generating surface.
[0011]
According to the inkjet recording head of the first aspect, the ink supply path is formed without including the pressure generating surface of the pressure chamber in contact with the actuator, and the ink flow direction in the ink supply path is parallel to the pressure generating surface. It is.
[0012]
Therefore, since the ink supply path is not in contact with the pressure generating surface, the ink supply path can maintain sufficient strength. For this reason, for example, even if the electric connection part has to be located on the upper surface of the ink supply path due to the high density of the nozzles, the ink supply path is deformed when making the electric connection to the actuator, The actuator will not be damaged.
[0013]
Further, the ink supply path is not formed in a vertical hole shape with the pressure generating surface, and the ink supply path is parallel to the pressure generating surface. Therefore, there is no problem of accuracy, a problem of high manufacturing cost, a problem of corrosion by ink, and the like due to processing into a hole shape by pressing or electroforming.
[0014]
An ink jet recording head according to a second aspect of the present invention is the ink jet recording head according to the first aspect, wherein the ink supply path is formed by a hole formed in an ink supply path plate.
[0015]
According to the inkjet recording head of the second aspect, the same operation as that of the first aspect is achieved, but since the ink supply path is constituted by the holes formed in the ink supply path plate, the pressure of the ink supply path is generated. The length in the direction perpendicular to the surface (hereinafter, this length is referred to as “the height of the ink supply path”) is the thickness of the ink supply path plate. The thickness of the ink supply path plate can be easily and accurately controlled at low cost. Therefore, the height of the ink supply path can be easily and accurately controlled at low cost.
An ink jet recording head according to a third aspect of the present invention is the ink jet recording head according to the second aspect, wherein the ink supply plate is provided between a nozzle plate forming the nozzle and a pressure chamber plate forming the pressure chamber. It is characterized by having.
[0016]
According to the ink jet recording head of the third aspect, the same operation as the second aspect is achieved, but the ink supply plate is located between the nozzle plate forming the nozzle and the pressure chamber plate forming the pressure chamber. The ink supply path plate is not in contact with the pressure generating surface. Therefore, the ink supply path can maintain sufficient strength.
[0017]
According to a fourth aspect of the present invention, in the ink jet recording head according to the third aspect, the ink supply plate is located between a pool plate forming the common ink chamber and the pressure chamber plate. Features.
[0018]
According to the ink jet recording head of the fourth aspect, the same operation as that of the second aspect is achieved, but since the ink supply plate is located between the nozzle plate forming the common ink chamber and the pool plate, the ink droplets are reduced. Assuming that the ejection direction is the vertical direction, the common ink chamber, the ink supply path, and the pressure chamber can be configured to overlap when viewed in the vertical direction. Therefore, the common ink chamber, the ink supply path, and the pressure chamber can be arranged with high density in the horizontal direction.
[0019]
An ink jet recording head according to a fifth aspect of the present invention is the ink jet recording head according to the second to fourth aspects, wherein the hole has a substantially rectangular shape that is long in the ink flow direction when viewed in plan. I have.
[0020]
According to the inkjet recording head of the fifth aspect, the same effect as that of the second to fourth aspects is obtained, but the holes formed in the ink supply plate serving as the ink supply path are provided with the ink when viewed in plan. It is a substantially rectangular shape that is long in the flow direction. Therefore, even if there is some processing error in the ink flow direction, the acoustic resistance and the inertance of the ink supply path are little affected.
[0021]
An ink jet recording head according to a sixth aspect of the present invention is the ink jet recording head according to the fifth aspect, wherein a direction perpendicular to the pressure generating surface of the ink supply path is a height H, and the height direction H is When the width D is orthogonal to the direction and the length in the ink flow direction is L, the relationship is L>D> H.
[0022]
According to the inkjet recording head of the sixth aspect, the same operation as that of the fifth aspect is achieved, but the height H and the height direction H are set such that the direction in which the ink supply path is perpendicular to the pressure generating surface of the ink supply path. When the width D is perpendicular to the width and the length in the ink flow direction is L, the acoustic resistance and the inertance of the ink supply path can be adjusted to the accuracy of the height H because L>D> H. Most dependent. Therefore, if the height H is processed with high precision, the acoustic resistance and inertance of the ink supply path can be controlled with high precision.
[0023]
Since the ink supply path is formed by holes formed in the ink supply path plate, the thickness of the ink supply path plate, that is, the height H of the ink supply path can be easily adjusted at low cost with high accuracy. Therefore, it is preferable.
[0024]
According to a seventh aspect of the present invention, in the ink jet recording head according to the sixth aspect, the height H, the width D, and the length L of the ink supply path have a relationship of L>2D> 3H. Features.
[0025]
According to the inkjet recording head of the seventh aspect, the same operation as that of the sixth aspect is achieved, but the height H, the width D, and the length L of the ink supply path have a relationship of L>2D> 3H. Therefore, the acoustic resistance and inertance of the ink supply path most depend on the accuracy of the height H, and there is no need to control the width D and the length L with high accuracy. Therefore, if only the height H is processed with high precision, even if the width D and the length L have some processing errors, the acoustic resistance and inertance of the ink supply path are little affected.
[0026]
In an ink jet recording head according to an eighth aspect of the present invention, in the configuration according to the sixth aspect, the width D, the height H, and the length L of the ink supply path are L> 200 μm, D> 100 μm, and 50 μm> H.
[0027]
According to the inkjet recording head of the seventh aspect, the same operation as the sixth aspect is achieved, but the width D, the height H, and the length L of the ink supply path are L> 200 μm, D> 100 μm, and 50 μm> Since it is H, the acoustic resistance and inertance of the ink supply path most depend on the accuracy of the height H. Therefore, if the height H is processed with high precision, the acoustic resistance and inertance of the ink supply path can be controlled with high precision.
[0028]
According to a ninth aspect of the present invention, in the ink jet recording head according to the seventh or eighth aspect, the width D, the height H, and the length L of the ink supply path are L> 300 μm, D> 120 μm, 40 μm> H.
[0029]
According to the ink jet recording head of the ninth aspect, the same operation as the seventh or eighth aspect is achieved, but the width D, the height H, and the length L of the ink supply path are L> 300 μm, D> Since 120 μm and 40 μm> H, if only the height H is processed with high accuracy, even if the width D and the length L have a processing error of about 10 μm, the acoustic resistance and the inertance of the ink supply path are affected. Few.
[0030]
According to a tenth aspect of the present invention, in the ink jet recording head according to the second to ninth aspects, the communication portion of the ink supply path that communicates with the common ink chamber has an opening in the common ink chamber. It is characterized by having a widened part wider than the part.
[0031]
According to the ink jet recording head of the tenth aspect, the same effect as that of the second to ninth aspects is obtained, but the communicating part of the ink supply path communicating with the common ink chamber is located closer to the opening of the common ink chamber. Since the widened portion is widened, even when the ink supply path plates are laminated, even if there is a slight displacement, the widened portion does not protrude from the opening of the common ink chamber.
[0032]
Therefore, the acoustic resistance and the inertance of the ink supply path plate are hardly affected by the stacking deviation.
[0033]
An ink jet recording head according to an eleventh aspect of the present invention is the ink jet recording head according to the second to ninth aspects, wherein the opening of the common ink chamber is wider than the communicating part of the ink supply path. It is characterized by.
[0034]
According to the ink jet recording head of the eleventh aspect, the same effect as that of the second to ninth aspects is obtained, but since the opening of the common ink chamber is wider than the communicating part of the ink supply path, When the ink supply path plates are stacked, even if the ink supply path plates are slightly misaligned, the communication portion of the ink supply path does not protrude from the opening of the common ink chamber.
[0035]
Therefore, the acoustic resistance and the inertance of the ink supply path plate are hardly affected by the stacking deviation.
[0036]
An ink jet recording head according to a twelfth aspect of the present invention is the ink jet recording head according to the first to eleventh aspects, wherein the nozzles are arranged in a matrix.
[0037]
According to the inkjet recording head of the twelfth aspect, the same operation as that of the first to eleventh aspects is achieved, but printing can be performed at high speed because the nozzles are arranged in a matrix.
[0038]
Further, since the ink supply path is not in contact with the pressure generating surface, the ink supply path has a sufficient strength. For this reason, as the nozzles are arranged in a matrix at a high density, the ink supply path is deformed when making an electric connection to the actuator, even if the electric connection part has to be located on the upper surface of the ink supply path. Or damage to the actuator.
[0039]
According to a thirteenth aspect of the present invention, in the ink jet recording head according to the first to twelfth aspects, the actuator is a piezoelectric element that presses the ink in the pressure chamber by an electrostrictive action. ,
According to a fourteenth aspect of the present invention, in the ink jet recording head according to the first to twelfth aspects, the actuator is a heating resistor that pressurizes the ink in the pressure chamber by heating and foaming the ink. Features.
[0040]
According to a fifteenth aspect of the present invention, there is provided an inkjet recording apparatus including the inkjet recording head according to any one of the first to fourteenth aspects.
According to the ink jet recording apparatus of the present invention, the ink jet recording head according to the present invention is provided with an ink jet recording head in which the acoustic resistance and inertance of the ink supply path are low cost and high accuracy. That is, an ink jet recording head having good ink ejection efficiency and a short meniscus decay time is provided.
[0041]
Therefore, the inkjet recording apparatus has a low manufacturing cost and can form a good image at high speed.
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of an inkjet recording head according to the present invention will be described with reference to FIGS.
[0043]
As shown in FIG. 1 or FIG. 2, the ink jet recording head 112 according to the present embodiment discharges ink droplets from nozzles 10 that discharge ink droplets that are opened in a matrix and a nozzle 10 that presses and communicates with ink. It has a pressure chamber 12 and a common ink chamber 14 to which ink is supplied from an ink supply member (not shown). A nozzle communication chamber 16 that communicates the nozzle 10 with the pressure chamber 12 and an ink supply path 18 that communicates the opening 20 of the common ink chamber 14 with the pressure chamber 12 are provided. As shown in FIG. 2A, a vibration plate 34 is bonded to the upper surface of the pressure chamber 12, a piezoelectric element 36 is bonded to the upper surface of the vibration plate 34, and a ball solder 40 is further bonded to the upper surface of the piezoelectric element 36. The electric board 38 is joined via the.
[0044]
Next, a method for manufacturing the inkjet recording head 112 according to the present embodiment will be described.
[0045]
The nozzle plate 22 in which the nozzle 10 is formed, the ink pool plates 24 and 26 forming the nozzle communication chamber 16 and the common ink chamber 14, and the through hole forming the nozzle communication chamber 16 and the opening 20 of the common ink chamber 14. The plate 28, the ink supply path plate 30 in which the ink supply paths 18 are formed, and the pressure chamber plate 32 in which the pressure chambers 12 are formed are sequentially laminated and joined.
[0046]
Since the ink supply path plate 30 is located between the ink pool plate 28 and the pressure chamber plate 32 as described above, if the direction in which ink droplets are ejected is set to the vertical direction, the common ink chamber 14, the ink supply path 18 and the pressure chamber 12 overlap each other. Therefore, the common ink chamber, the ink supply path, and the pressure chamber can be arranged with high density in the horizontal direction. That is, the nozzles 10 can be arranged in a matrix at a high density.
[0047]
Next, the surface of the nozzle plate 22 is coated with a water-repellent coating film, and the nozzle 10 is opened with an excimer laser. Then, after forming the nozzle 10, the vibration plate 34 is bonded to the pressure chamber plate 32.
[0048]
The material of the nozzle plate 22 is polyimide, and the material of the ink pool plates 24 and 26, the through plate 28, the ink supply path plate 30, the pressure chamber plate 32, and the vibration plate 34 is SUS. The diaphragm 34 is about 20 μm, the pressure chamber plate 32 is about 100 μm, the ink supply path plate 30 is about 30 μm, the through plate 28 is about 150 μm, the pool plate 24 is about 200 μm, and the pool plate 36 is about 150 μm.
[0049]
As shown in FIG. 2, the ink supply path plate 30 is formed by etching a substantially rectangular hole having a width D of about 140 μm and a length L of about 320 μm on a plate having a thickness (H) of about 30 μm. . This hole becomes the ink supply path 18. In other words, the shape of the ink supply path 18 is a groove having a rectangular section having a height H (about 30 μm) and a width D (about 140 μm) and a length L (about 320 μm).
[0050]
Further, the portion of the ink supply passage 18 communicating with the common ink chamber 14 has a widened portion 18A having a diameter φ1 (about 200 μm) wider than the diameter φ2 (about 150 μm) of the opening 20 of the common ink chamber 14. I have. For this reason, the displacement of the ink supply path plate 30 can be tolerated up to FIG. 3B in the communicating portion with the opening 20 of the common ink chamber 14. The maximum stacking deviation due to a manufacturing error in the present embodiment is shown in FIG. 3B, and does not reach the state shown in FIG. 3C.
[0051]
Therefore, the acoustic resistance and inertance of the ink supply path 18 which affect the ink droplet ejection efficiency and the meniscus decay time, which will be described later, are not affected by the stacking deviation.
[0052]
Next, a peelable adhesive, for example, a piezoelectric plate bonded to a fixed substrate via a heat-foamable adhesive film having a property of being foamed and greatly reduced in adhesive strength when heated at a predetermined temperature after bonding. Next, the piezoelectric elements 36 arranged in a matrix are formed by using, for example, sandblasting.
[0053]
The surface of the piezoelectric element 36 opposite to the fixed substrate is joined to the diaphragm 34. Note that first and second electrode layers are formed in advance on both surfaces of the piezoelectric element 36 as electrode layers by sputtering or the like, and the first and second electrode layers are adhered to the vibration plate 34 also serving as a common electrode with a conductive adhesive. One electrode layer, that is, the piezoelectric element 36 and the vibration plate 34 are also electrically connected.
[0054]
Subsequently, the fixed substrate is heated to reduce the adhesive force of the thermally foamable adhesive film, and the fixed substrate is peeled off.
[0055]
After peeling, a ball solder 40 is formed for each piezoelectric element 36, and an electric board 38 is bonded thereon. As described above, since the first and second electrode layers are formed on both surfaces of the piezoelectric element 36, the second electrode layer, that is, the piezoelectric element 36 and the electric substrate 38 are electrically connected. In addition, the electric board 38 and the diaphragm 34 are connected by a contact (not shown).
[0056]
In addition, as the nozzles 10 are arranged in a matrix and the density is increased, the configuration in which the electrical connection to the piezoelectric element 36 is located on the upper surface of the ink supply path 18 is inevitable.
[0057]
However, the upper surface of the ink supply path 18 is formed by the pressure chamber plate 32 instead of the vibration plate 34, and the ink supply path 18 has sufficient strength. Therefore, since the electrical contacts of the ball solder 40 are interposed in the electrical connection process via the pressure chamber plate 32, the ink supply path 18 is pressurized and the ink supply path 18 is deformed. 36 is not damaged.
[0058]
Finally, by attaching an ink supply member (not shown) or the like, the ink jet recording head 112 of the present embodiment is completed.
[0059]
Next, the operation of the inkjet recording head 112 according to the present embodiment will be described.
[0060]
As shown by the arrow in FIG. 1B, ink introduced from an ink supply port (not shown) of the ink jet recording head 112 is filled in the common ink chamber 14, and the pressure from the common ink chamber 14 passes through the ink supply path 18 to each pressure. The chamber 12 is filled with ink. When the pressure chambers 12 are filled with ink, for example, when current is supplied from the ball solder 40 to the vibration plate 34, the piezoelectric element 36 is distorted, and the ink in the pressure chambers 12 is pressurized via the vibration plate 34, and a nozzle is formed. An ink droplet is ejected from 10. At this time, the ink in the pressure chamber 12 also flows back to the ink supply path 18. If the reverse flow rate is large, the ejection efficiency of the ink droplets deteriorates.
[0061]
After the ink droplets are ejected, the ink is refilled into the pressure chamber 12 from the common ink chamber 14 through the ink supply path 18, and the movement of the meniscus of the ink in the nozzle 10 is attenuated and stabilized. Can be discharged. Note that the maximum drive frequency for continuously ejecting ink droplets, that is, the print recording speed also depends on the time during which the movement of the meniscus is attenuated and stabilized. Therefore, it is necessary to quickly stabilize the meniscus of the ink of the nozzle 10.
[0062]
Here, the movement of the meniscus will be described below.
[0063]
FIG. 4 schematically illustrates the operation of the meniscus 50 in the nozzle 10 before and after the droplet discharge, in order from (A) to (F). The meniscus 50 (FIG. 4A), which has been slightly depressed, causes the nozzle 10 to eject the ink droplet 52 when the pressure chamber 12 is compressed (FIG. 4B). When the ink droplets 52 are ejected, the amount of ink inside the nozzles 10 decreases, so that a concave meniscus 50 is formed (FIG. 4C). The concave meniscus 50 gradually returns to the opening of the nozzle 10 by the action of the surface tension of the ink (FIGS. 4D and 4E), and recovers to the state before ejection (FIG. 4). (F)). The operation of returning the meniscus 50 after the ejection of the ink droplet 52 is hereinafter referred to as “refill”, and the time until the meniscus 50 returns to the opening surface 22A of the nozzle 10 after the ejection of the ink droplet 52 and is stabilized. Is called the meniscus decay time.
[0064]
FIG. 5 is a graph showing the relationship between the elapsed time immediately after the ejection of the ink droplet 52 and the change in the position of the meniscus 50 (the center position y of the meniscus 50, see FIG. 4C). The meniscus 50 (y = −60 μm) that has largely retreated immediately after ejection (t = 0) returns to the initial position (y = 0) while vibrating as shown in this graph.
[0065]
The shape of the ink supply path 18 has a great influence on the ejection efficiency of the ink droplets 52 and the meniscus decay time. That is, in the ink supply path 18, it is difficult to cause the ink to flow backward from the pressure chamber 12 to the common ink chamber 14, and it is desired to increase the acoustic resistance of the ink supply path 18 in order to efficiently eject the ink droplet 52 from the nozzle 10. However, when the acoustic resistance is increased, the inertance of the ink supply path 18 is also increased, so that the meniscus 50 becomes difficult to stabilize after the ink droplet 52 is ejected from the nozzle 10. Therefore, a design that balances acoustic resistance and inertance is important. In other words, it is desired that the shape has a large acoustic resistance and a small inertance.
[0066]
In the present embodiment, as described above, the ink supply path 18 has a rectangular cross section having a height H (about 30 μm) and a width D (about 140 μm) and a length L (about 320 μm). Thus, the shape is such that the acoustic resistance is large and the inertance is not so large. That is, the shape is such that high ejection efficiency and a sufficiently short meniscus decay time can be obtained. Since the height H is small and the width D and the length L are large, the accuracy of the height H has the greatest influence on the acoustic resistance and inertance thereof as described later.
[0067]
However, in this embodiment, since the ink supply path 18 is a hole formed in the ink supply path plate 30 in a substantially rectangular shape by etching, the height H becomes the thickness of the ink supply path plate 30 and can be processed with high precision. On the other hand, the width D and the length L of the ink supply path 18 cannot be processed with high precision because they are holes formed by etching. However, since the width D and the length L are large, as described later, the processing precision is low. Has no problem because it has little effect on acoustic resistance and inertance.
[0068]
Therefore, the ink supply path 18 can produce the acoustic resistance and the inertance with high accuracy and at low cost. The upper surface of the ink supply path 18 is formed by the pressure chamber plate 32 instead of the vibration plate 34, and the ink supply path 18 maintains sufficient strength.
[0069]
Now, the relationship between the acoustic resistance and inertance of the ink supply path 18 and the processing accuracy will be described in detail below.
[0070]
In a rectangular section having a width Dm and a height Hm, a flow path having a length Lm is provided with a viscosity (Pa · s) and a density ρ (kg / m ³ ), The inertance of the flow path when the liquid flows (kg / m ⁴ ), Acoustic resistance (Ns / m ⁵ ) Can be calculated by the equations (1) and (2) in FIG.
[0071]
The ink used in the present embodiment has an ink viscosity of about 0.003 (Pa · s) and an ink density ρ of about 998 (kg / m ³ As described above, the width D is about 0.00014 m (140 μm), the height H is about 0.00003 m (30 μm), and the length L is about 0.00032 m (320 μm). Therefore, when these numerical values are put into equations (1) and (2) in FIG. 10 and calculated, the inertance is 7.60E + 07 (Kg / m2). ⁴ ), The acoustic resistance is 3.47E + 12 (Ns / m ⁵ ).
[0072]
Now, for example, if a manufacturing error occurs such that the width D and the height H are larger than the design values by 10 μm, the error between the design values of the width D and the height H and the design values of the inertance and the acoustic resistance are as shown in FIG. It becomes like the graph of. According to this graph, since the width D is 140 μm, the inertance and the acoustic resistance are both reduced to about 7% even if a manufacturing error occurs in which the width D is increased by 10 μm, that is, the width is 150 μm. However, since the height H is 30 μm, if the height H is increased by 10 μm, that is, if a manufacturing error occurs when the height H is 40 μm, the inertance decreases by about 25% and the acoustic resistance decreases by about 42%.
[0073]
If the error between the inertance and the acoustic resistance is about 10% or less, the variation in the ejection characteristics of the ink droplets is limited to the image quality that cannot be recognized by human eyes. That is, if the error of the inertance and the acoustic resistance is about 10% or less, the image quality is not affected.
[0074]
Also, as for the length L, since L is in the numerator in both the formulas (1) and (2) in FIG. 10, even if a manufacturing error occurs in which 320 μm (L1) is increased by 10 μm to 330 μm (L2), As shown by the equation (3) in FIG. 10, the influence is only about 3%.
[0075]
Therefore, in the case of the shape of the ink supply path as in the present embodiment, the height H has the largest influence on the inertance and the acoustic resistance with respect to the manufacturing error. In other words, in the case of the shape of the ink supply path as in the present embodiment, if only the height H is processed with high precision, the acoustic resistance and inertance can be controlled with high precision.
[0076]
The ink supply path 18 of the present embodiment is a hole formed in the ink supply path plate 30 in a substantially rectangular shape by etching, and the height H is the thickness of the ink supply path plate 30 and can be set with high accuracy. is there.
[0077]
In general, in the case of processing by etching, a manufacturing error of several μm occurs. If the groove depth (the height H of the ink supply path 18) is processed by etching, that is, if the processing is performed on the pressure chamber plate 32 without providing the ink supply path plate 30, the groove depth may have an error of about several μm. Occurs. Moreover, the processing in the depth direction generally has lower processing accuracy than the processing in the width direction, and an error of about 10 μm occurs. As described above, in order to reduce the error of inertance and acoustic resistance to about 10% or less which does not affect image quality even with such processing accuracy, a dimension of 100 μm or more is required from the graph of FIG. And
[0078]
If the ink supply path having a width D and a height H of 100 μm or more has a large cross-sectional area, the acoustic resistance (3.47E + 12 (Ns / m ⁵ )), It is necessary to make the length L about 4000 μm (4 mm), which is impractical.
[0079]
When the groove-shaped ink supply path 18 is formed in consideration of the processing accuracy of the etching, the cross-sectional area increases and the acoustic resistance decreases. It is also impractical to increase the acoustic resistance by making the ink supply path 18 longer. Therefore, by making the height H small, that is, the thickness of the ink flow path plate 30 and increasing the width D, it is possible to design such that the acoustic resistance is large and the inertance is not so large.
[0080]
Since the opening 20 of the through plate 28 has a larger cross-sectional area and a shorter length (in this case, the thickness of the through plate 28) than the ink supply path 18, inertance and acoustic resistance are smaller than those of the supply path. However, the manufacturing error in this portion hardly affects the characteristics.
[0081]
Next, a second embodiment of the ink jet recording head according to the present invention will be described with reference to FIGS.
[0082]
The members described in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.
[0083]
In the ink jet recording head 113 of this embodiment, as shown in FIG. 7, the ink supply path plate 31 has no widened portion, the opening 21 of the common ink chamber 14 has a diameter φ3 of about 200 μm, and the ink supply path 19 The configuration is the same as that of the first embodiment except that the width is wider than the communication portion having the width D (about 140 μm).
[0084]
As described above, since the opening 21 of the common ink chamber 14 has a diameter φ3 (about 200 μm) larger than the width D (about 140 μm) of the ink supply path plate 31, the misalignment of the ink supply path plate 31 is common. The communicating portion with the opening 21 of the ink chamber 14 is permissible up to FIG. It should be noted that the maximum stacking deviation due to a manufacturing error in the present embodiment is shown in FIG. 8B, and does not reach the state shown in FIG. 8C.
[0085]
Therefore, the acoustic resistance and inertance of the ink supply path 18 which affect the ink droplet ejection efficiency and the meniscus decay time are not affected by the stacking deviation.
[0086]
Next, the operation of the inkjet recording head 113 according to the second embodiment will be described.
[0087]
Since the ink supply path 19 of the second embodiment has the same configuration as that of the first embodiment, the acoustic resistance and inertance of the ink supply path 19 are most affected by the accuracy of the height H.
[0088]
However, as in the first embodiment, since the ink supply path 19 is a hole formed in the ink supply path plate 31 in a substantially rectangular shape by etching, the height H becomes the thickness of the ink supply path plate 31 and can be processed with high precision. In this configuration, the acoustic resistance and inertance can be controlled with high accuracy at low cost.
[0089]
Next, an ink jet recording apparatus 102 including the ink jet recording head 112 of the first embodiment or the ink jet recording head 113 of the second embodiment will be described with reference to FIG.
[0090]
The inkjet recording apparatus 102 includes a carriage 104 on which the inkjet recording head 112 or the inkjet recording head 113 is mounted, a main scanning mechanism 106 for scanning the carriage 104 in the main scanning direction M, and a recording sheet P as a recording medium in the sub scanning direction S. A sub-scanning mechanism 108 for scanning and a maintenance station 110 are included.
[0091]
The inkjet recording head 112 or the inkjet recording head 113 is mounted on the carriage 104 such that the nozzle plate 22 in which the nozzles 10 are formed faces the recording paper P, and is moved in the main scanning direction M by the main scanning mechanism 106. By discharging ink droplets onto the recording paper P, an image is recorded on a certain band area BE. When one movement in the main scanning direction is completed, the recording paper P is conveyed in the sub-scanning direction S by the sub-scanning mechanism 108, and the next band area BE is recorded while the carriage 104 is moved in the main scanning direction M again. . By repeating such an operation a plurality of times, image recording can be performed over the entire surface of the recording paper P.
[0092]
The ink jet recording head 112 or the ink jet recording head 113 of the present embodiment has a number of nozzles 10 arranged in a matrix. Therefore, an image can be formed in a wide band area BE by one movement of the carriage 104 in the main scanning direction M. That is, image recording can be performed over the entire surface of the recording paper P with a small number of movements of the carriage 104. Further, as described above, since the ink supply path 18 or the ink supply path 19 having the sufficiently short meniscus decay time is provided, the driving frequency can be increased. Therefore, high-speed image formation is possible.
[0093]
Further, since the ink supply path 18 or the ink supply path 19 having high ejection efficiency is provided, good and stable image formation can be performed.
Accordingly, the ink jet recording apparatus 102 can perform good and stable image formation at high speed.
[0094]
Note that the present invention is not limited to the above embodiment.
[0095]
For example, in the above embodiment, the piezoelectric element 36 pressurizes the pressure chamber 12 by the flexural vibration of one piezoelectric element 36, but is not limited thereto. For example, a form in which piezoelectric elements are stacked or a longitudinal vibration type piezoelectric element may be used. Alternatively, other types of piezoelectric elements may be used.
[0096]
Further, for example, in the above-described embodiment, the actuator is formed of the piezoelectric element 36, but is not limited thereto. For example, a heating resistor which pressurizes the ink in the pressure chamber by heating and foaming the ink may be used, or a device using electrostatic force or magnetic force may be used. Alternatively, other types of actuators may be used.
[0097]
Further, for example, in the above embodiment, the nozzles 10 are arranged in a matrix, but the present invention is not limited to this. For example, the nozzles may be arranged in one row.
[0098]
Further, for example, in the above-described embodiment, printing is performed while the inkjet recording head 112 or the inkjet recording head 113 is transported by the carriage 104, but the invention is not limited to this. For example, an inkjet recording head having nozzles arranged over the entire recording medium may be used, the inkjet recording head may be fixed, and recording may be performed while transporting only the recording medium.
[0099]
Further, the ink jet recording in this specification is not limited to the recording of characters and images on recording paper. That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, ink is discharged onto a polymer film or glass to create a color filter for display, or solder in a welded state is discharged onto a substrate to form bumps for component mounting, for industrial use. The present invention can be applied to all droplet ejecting apparatuses used.
[0100]
【The invention's effect】
As described above, the ink supply path of the ink jet recording head according to the present invention can produce acoustic resistance and inertance with high accuracy and at low cost. Has strength.
[Brief description of the drawings]
FIG. 1 is a cross-sectional perspective view illustrating a main part of an inkjet recording head according to a first embodiment of the present invention. FIG. (B) is an enlarged view of a portion X in FIG. (A).
FIG. 2 is a cross-sectional view illustrating the inkjet recording head according to the first embodiment of the present invention. FIG. (B) is a sectional view taken along the line AA of FIG. (A).
FIG. 3 is an explanatory diagram illustrating a stacking deviation of an ink supply path plate of the inkjet recording head according to the first embodiment of the present invention.
FIG. 4 is an explanatory diagram schematically showing a meniscus change when ink is ejected from a nozzle of an ink jet recording head.
FIG. 5 is a graph showing an example of a relationship between a meniscus attenuation and a center position of a meniscus when ink is ejected from a nozzle of an ink jet recording head.
FIG. 6 is a graph showing a relationship between a manufacturing error of an ink supply path and inertance and acoustic resistance.
FIG. 7 is a cross-sectional view illustrating an inkjet recording head according to a second embodiment of the present invention. FIG. (B) is a sectional view taken along the line BB of FIG. (A).
FIG. 8 is an explanatory diagram for explaining lamination misalignment of an ink supply path plate of an inkjet recording head according to a second embodiment of the present invention.
FIG. 9 is a sectional perspective view showing an ink jet recording apparatus provided with an ink jet recording head according to the first embodiment or the second embodiment of the present invention.
FIG. 10: inertance (kg / m ⁴ ), Acoustic resistance (Ns / m ⁵ ) And (3) calculating the effect of the manufacturing error of the length L.
[Explanation of symbols]
10 nozzles
12 pressure chamber
14 Common ink chamber
18, 19 Ink supply path
18A Wide section
20, 21 opening
30 Ink supply path plate
34 diaphragm (pressure generating surface)
36 Piezoelectric element (actuator)
102 Inkjet storage device
112, 113 inkjet recording head

Claims (15)

An ink supply path is provided that communicates the opening of the common ink chamber with the pressure chamber and supplies ink from the common ink chamber to the pressure chamber. The ink in the pressure chamber is pressurized by an actuator to eject ink droplets from the nozzles. In the ink jet recording head to be
The ink supply path is formed without including a pressure generation surface of the pressure chamber in contact with the actuator, and an ink flow direction in the ink supply path is parallel to the pressure generation surface. Ink jet recording head. 2. The ink jet recording head according to claim 1, wherein the ink supply path is formed by a hole formed in the ink supply path plate. The ink jet recording head according to claim 2, wherein the ink supply plate is located between a nozzle plate forming the nozzle and a pressure chamber plate forming the pressure chamber. The ink jet recording head according to claim 3, wherein the ink supply path plate is located between a pool plate forming the common ink chamber and the pressure chamber plate. The ink jet recording head according to claim 2, wherein the hole has a substantially rectangular shape that is long in a flow direction of the ink when viewed in a plan view. When a height H is a direction orthogonal to the pressure generating surface of the ink supply path, a width D is a direction orthogonal to the height direction H, and L is a length in the ink flow direction, L> D> 6. The ink jet recording head according to claim 5, having a relationship of H. 7. The ink jet recording head according to claim 6, wherein the height H, width D, and length L of the ink supply path have a relationship of L> 2D> 3H. 7. The ink jet recording head according to claim 6, wherein the width D, height H, and length L of the ink supply path satisfy L> 200 μm, D> 100 μm, and 50 μm> H. 9. The ink jet recording head according to claim 7, wherein a width D, a height H, and a length L of the ink supply path satisfy L> 300 μm, D> 120 μm, and 40 μm> H. 10. 10. The ink-jet recording according to claim 2, wherein a communicating portion of the ink supply path communicating with the common ink chamber has a widened portion wider than an opening of the common ink chamber. head. 10. The ink jet recording head according to claim 2, wherein an opening of the common ink chamber is wider than a communication part of the ink supply path. The ink jet recording head according to claim 1, wherein the nozzles are arranged in a matrix. 13. The ink jet recording head according to claim 1, wherein the actuator is a piezoelectric element that presses ink in the pressure chamber by an electrostrictive action. 13. The inkjet recording head according to claim 1, wherein the actuator is a heating resistor that pressurizes the ink in the pressure chamber by heating and foaming the ink. An inkjet recording apparatus comprising the inkjet recording head according to claim 1.

Images