Liquid ejection head and liquid ejection device

Abstract

To provide a liquid ejection head which can reduce pressure fluctuation in a liquid flow passage and is easy to manufacture.SOLUTION: A liquid ejection head includes: a nozzle 11 that ejects a liquid; a flow passage member 212 having a liquid flow passage 210 communicating with the nozzle; and pressure generating means 220 that varies a pressure of the liquid in the liquid flow passage. At least a part of the flow passage member is provided with a groove forming portion 202 having a plurality of groove portions 204 formed by at least one of a plurality of recessed parts or a plurality of projecting parts and arranged on a side of the liquid flow passage. The groove forming portion has a contact angle of 90° or more to the liquid at least in a cross section of the recessed parts or the projecting parts in a direction in which they are arranged.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] It is known that in a liquid ejection head, pressure is applied to the liquid in the liquid flow path to eject the liquid from the nozzle. It is known that pressure fluctuations occur in the liquid flow path when ejecting the liquid, which affects the ejection characteristics of the liquid. In response to this, for example, proposals such as those shown in Patent Document 1 have been made.

[0003] Patent Document 1 discloses a liquid ejection device having a compliant microstructure in a feed channel (common liquid chamber) that supplies fluid to a pressure chamber (pressure chamber). Patent Document 1 also describes that the compliance of the compliant microstructure attenuates the energy of pressure fluctuations generated in a fluid ejector connected to the feed channel, thereby reducing the effect of pressure fluctuations on other fluid ejectors. Patent Document 1 also discloses that the compliant microstructure is configured by a recess covered with a thin film in the feed channel.

[0004] According to Patent Document 1, it is possible to reduce fluid crosstalk between fluid ejectors connected to the same inlet or outlet feed channel, thereby stabilizing the droplet size and velocity of fluid ejected from each fluid ejector, enabling precise and accurate printing. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configurations using thin films (silicon or metal) described in the prior art, it is difficult to increase compliance, and a complex processing process is required to form the hollow structure of the compliant microstructure. Therefore, in the prior art, it is difficult to sufficiently reduce pressure fluctuations in the liquid flow path, and the complicated processing makes the device more complicated, increasing the manufacturing cost.

[0006] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a liquid ejection head that is capable of reducing pressure fluctuations within a liquid flow path and that is easy to manufacture. [Means for solving the problem]

[0007] In order to solve the above problems, the liquid ejection head of the present invention comprises a nozzle for ejecting liquid, a flow path member forming a liquid flow path communicating with the nozzle, and a pressure generating means for varying the pressure of the liquid in the liquid flow path, and is characterized in that at least a part of the flow path member is provided with a groove forming portion having an array of at least one of recesses or protrusions on the liquid flow path side, and having a plurality of grooves formed by the recesses or protrusions, and the groove forming portion has a contact angle with the liquid of 90° or more, at least in a cross section in the arrangement direction of the recesses or protrusions. Effect of the Invention

[0008] According to the present invention, it is possible to provide a liquid ejection head that can reduce pressure fluctuations inside a liquid flow path and is easy to manufacture. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view for explaining an example of a groove forming portion and an example of a contact angle θ. FIG. [Diagram 2] FIG. 2A is a cross-sectional schematic diagram showing an example of a flow path member without a groove forming portion, FIG. 2B is a cross-sectional schematic diagram showing an example of a flow path member with a groove forming portion, and FIG. 2C is a cross-sectional schematic diagram for explaining an example of an air layer. [Diagram 3] 1A and 1B are cross-sectional schematic diagrams illustrating an example of a gas layer. [Figure 4] 5A to 5C are schematic cross-sectional views for explaining an example of the interval and width of grooves. [Diagram 5] 13A is a schematic cross-sectional view illustrating another example of the air layer, and FIG. 13B is a schematic cross-sectional view illustrating another example of the interval and width of the groove portion. [Figure 6]1A and 1B are schematic diagrams illustrating an example of a method for measuring a contact angle. [Figure 7A] 5A and 5B are schematic diagrams illustrating an example of the shape of a liquid flow path and another example of a groove-forming portion. [Figure 7B] 5A and 5B are schematic diagrams illustrating an example of the shape of a liquid flow path and another example of a groove-forming portion. [Figure 8] 5A to 5C are schematic diagrams illustrating other examples of the shape of the liquid flow path. [Figure 9] 1A to 1C are schematic diagrams illustrating an example in which groove-formed portions are provided on two adjacent surfaces. [Figure 10] 5A to 5C are schematic diagrams illustrating an example of a method for forming a groove formation portion. [Figure 11] FIG. 4 is a schematic cross-sectional view for explaining an example of a pressure generating means and a nozzle. [Figure 12] 2A to 2C are schematic diagrams illustrating an example of a liquid-repellent layer. [Figure 13A] 5A and 5B are a schematic cross-sectional view and a schematic plan view for explaining an example of an individual liquid chamber and a common liquid chamber. [Figure 13B] 13A(A) is a schematic cross-sectional view for explaining an example of a case where a groove forming portion is provided and an example of residual vibration, and FIG. 13B is a schematic cross-sectional view for explaining an example of an air layer. [Figure 14A] 1A is a schematic cross-sectional view illustrating an example of an individual liquid chamber, a supply-side common liquid chamber, and a recovery-side common liquid chamber; FIG. [Figure 14B] FIG. 14A(A) is a schematic cross-sectional view for explaining an example of a case where a groove forming portion is provided and an example of residual vibration, and FIG. 14A(B) is a schematic plan view for explaining an example of residual vibration. [Figure 15] 1A and 1B are plan schematic views for explaining an example of a groove forming portion. [Figure 16] FIG. 15(A) is a schematic plan view for further illustrating FIG. [Figure 17]13A and 13B are plan schematic views for explaining another example of a groove formation portion. [Figure 18] 13A and 13B are schematic cross-sectional views for explaining other examples of a groove formation portion. [Figure 19] 1A is a schematic plan view illustrating another example of a groove formation portion, and FIG. 1C is a schematic cross-sectional view thereof. [Figure 20] 6A to 6C are schematic cross-sectional views illustrating other examples of a groove formation portion. [Figure 21] 4A to 4C are schematic views for explaining an example of a through-hole forming portion. [Figure 22] 1 is a schematic cross-sectional view for explaining an example of a groove forming portion and an example of a contact angle θ. FIG. [Figure 23] 4A and 4B are schematic cross-sectional views for explaining an example of a through-hole forming portion. [Figure 24] 10A and 10B are schematic cross-sectional views for explaining an example of the interval and width of through holes. [Diagram 25] FIG. 2 is an exploded perspective view illustrating an example of a head module. [Figure 26] FIG. 2 is an exploded perspective view of the head module as viewed from the nozzle surface side. [Figure 27] FIG. 2 is an exploded perspective view illustrating a head, a base member, and a cover member of the head module. [Figure 28] FIG. 2 is an explanatory cross-sectional view taken along a short side direction of the head in an example of a head module. [Figure 29] FIG. 11 is a schematic exploded perspective view illustrating another example of a liquid ejection head according to the present invention. [Diagram 30] FIG. 4 is a schematic cross-sectional view for explaining another example of a liquid ejection head of the present invention. [Diagram 31] FIG. 4 is a schematic cross-sectional view for explaining another example of a liquid ejection head of the present invention. [Diagram 32] FIG. 4 is a schematic cross-sectional view for explaining another example of a liquid ejection head of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A liquid ejection head and a liquid ejection device according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and may be modified within the scope of what a person skilled in the art can imagine, such as other embodiments, additions, modifications, deletions, etc., and any aspect is within the scope of the present invention as long as it provides the functions and effects of the present invention.

[0011] The liquid ejection head of the present invention comprises a nozzle for ejecting liquid, a flow path member forming a liquid flow path communicating with the nozzle, and a pressure generating means for varying the pressure of the liquid in the liquid flow path, and is characterized in that at least a portion of the flow path member is provided with a groove forming portion having an array of at least one of recesses or protrusions on the liquid flow path side, and having a plurality of grooves formed by the recesses or protrusions, and the groove forming portion has a contact angle with the liquid of 90° or more, at least in a cross section in the arrangement direction of the recesses or protrusions.

[0012] The present invention provides a groove forming section that holds an air layer or the like in a liquid flow path of a liquid ejection head, thereby making it possible to reduce pressure fluctuations occurring in the liquid flow path due to high compliance of the air layer or the like. In particular, by providing a groove forming section that has liquid repellency (contact angle with respect to liquid of 90° or more) in the liquid flow path and stably forming and holding an air layer, high compliance can be formed in the liquid flow path. Therefore, the present invention can attenuate pressure fluctuations in the liquid flow path. Note that residual vibrations occur in the liquid flow path when ejecting or supplying liquid, and the residual vibrations cause pressure fluctuations in the liquid flow path.

[0013] In the configurations using thin films (silicon or metal) described in the prior art, it is difficult to increase compliance, and a complex processing process is required to form the hollow structure of the compliant microstructure. In addition, in the prior art, the retention force of the formation layer (damper layer, air layer) is low, and ingenuity is required to prevent the formation layer from breaking, and it is also necessary to secure the installation space for the formation layer. If the formation layer breaks, it is not possible to reduce the residual vibration in the liquid flow path, and air bubbles may be mixed into the liquid flow path, causing other problems.

[0014] Therefore, in the prior art, it is difficult to sufficiently reduce pressure fluctuations in the liquid flow path, and the complicated processing makes the device more complicated, leading to increased manufacturing costs. On the other hand, in the present invention, the air layer (or gas layer) held in the groove formation portion having liquid repellency makes it possible to obtain high compliance, thereby reducing pressure fluctuations in the liquid flow path and obtaining a liquid ejection head that is easy to manufacture.

[0015] (First embodiment) An embodiment of the liquid ejection head of the present invention will be described.

[0016] An example of the groove formation portion will be described using the theory of the water-repellent structure. 1 is a diagram showing a schematic diagram of a state when liquid comes into contact with grooved portion 202. Grooved portion 202 has a plurality of grooves 204 formed by recesses or protrusions.

[0017] When viewed from the liquid 200 side, the groove formation portion 202 can be considered to be formed, for example, from material A and material B. Material A is a portion that is convex on the liquid flow path 210 side, and can be considered to be a contact portion that comes into contact with the liquid 200 (e.g., ink). Material A is, for example, a flow path member. Material B is a portion that is concave on the liquid flow path 210 side, and can be considered to be a non-contact portion that does not come into contact with the liquid 200. Material B is, for example, air. The groove formation portion 202 can be considered to be a fine structure made of material A and material B. The groove formation portion 202 may be referred to as a fine structure, etc.

[0018] The spacing between grooves 204 in one direction is represented, for example, by a1, a2,..., and the average spacing between grooves 204 is represented, for example, by a. The width of grooves 204 in one direction is represented, for example, by b1, b2,..., and the average spacing between grooves 204 is represented, for example, by b. This will also be described later with reference to FIG. 4 etc.

[0019] The liquid in contact with the surface of a microstructure made of two kinds of materials A and B can be considered according to the Cassie-Baxter theory (also called the Cassie-Baxter model). In this case, the contact angle θ of the liquid 200 can be expressed by the Cassie-Baxter equation as shown in the following formula (1).

[0020] cosθ=a×cosθa+b×cosθb Equation (1)

[0021] In the above formula (1), θa is the static contact angle between the liquid and the surface of substance A, and θb is the static contact angle between the liquid and the surface of substance B. The static contact angle is sometimes simply referred to as the contact angle.

[0022] In the above formula (1), the part a is generally represented by the proportion of substance A in the outer periphery of the liquid where the liquid is in contact with the groove forming portion 202. Also, the part b is generally represented by the proportion of substance B in the outer periphery of the liquid where the liquid is in contact with the groove forming portion 202. In this embodiment, the above formula (1) is defined using the interval and width of the groove portions 204 in one direction, and using the average interval a of the groove portions 204 in one direction and the average width b of the groove portions 204.

[0023] In the above formula (1), when the contact angle θ is 90° or more, it can be said that the surface of the microstructure has liquid repellency. In the illustrated example, the upper limit of θ is 180°. When the surface of a microstructure has liquid repellency, it is sometimes referred to as the microstructure having a liquid repellent structure. In this example, material A in groove formation portion 202 corresponds to the flow path member, and material B in groove formation portion 202 corresponds to a gas (e.g., air).

[0024] When material A is used as a flow path member and material B is air, the contact angle θb between the air and the liquid is a constant depending on the liquid. Therefore, the liquid repellency of the surface of the microstructure formed by materials A and B can be adjusted by appropriately selecting the relationship between a and b, or by selecting a flow path member such that the contact angle θa between material A and the liquid is 90°≦θa<180°.

[0025] According to an experimental report by Barthlott et al. (Furstner, R., Barthlott, W., Neinhuis, C., Walzel, P., “Wetting and self-cleaning properties of artificial superhydrophobic surfaces”, Langmuir, Vol. 21, No. 3 (2005), pp. 956-961.), the lotus effect can be achieved, for example, as follows: When the average length of material A in one direction in groove formation portion 202 is a and the average length of material B in said one direction is b, it is preferable to set b / a to 2 or less.

[0026] That is, it is preferable to use the following formula (2). b / 2≦a Formula (2) This will also be explained in FIG. 4 etc. described later.

[0027] The liquid repellency of the groove formation portion 202 against liquid may be referred to as water repellency etc. In this embodiment, the type of liquid is not particularly limited, and may or may not contain water.

[0028] In this embodiment, the groove forming portion 202 has a contact angle θ of 90° or more with respect to the liquid 200 at least in a cross section in the arrangement direction of the concave portions or convex portions. FIG. 1 shows a cross section in the arrangement direction of the concave portions or convex portions, and illustrates that the groove forming portion 202 has a contact angle θ of 90° or more with respect to the liquid. By having a contact angle θ of 90° or more, the groove forming portion 202 has liquid repellency with respect to the liquid 200, and an air layer 206 is formed in the groove portion 204. As described below, the air layer 206 can compress or rebound (expand) in response to pressure fluctuations in the liquid flow path 210, thereby attenuating the pressure fluctuations. As described below, the groove forming portion 202 may hold a gas layer 208 or the like instead of the air layer 206, and even if the gas layer 208 is used, the same effect as the air layer 206 can be obtained.

[0029] The contact angle θ of the groove formation portion 202 with respect to the liquid 200 in a cross section in the arrangement direction of the recesses or protrusions may be referred to as the contact angle θ of the groove formation portion 202. In addition, the contact angle θ of the groove formation portion 202 may be simply referred to as the contact angle θ.

[0030] Next, it will be described how the groove formation portion 202 attenuates pressure fluctuations of the liquid in the liquid chamber (also called a liquid flow path, a flow path, etc.).

[0031] In the example of the groove forming portion 202 shown in FIG. 1, the groove forming portion 202 has a plurality of grooves formed by recesses or protrusions, forming a microstructure. In such a microstructure, when liquid is present in the liquid chamber, the liquid cannot reach the bottom of the groove, and air remains below the liquid. Therefore, air is held in the grooves of the groove forming portion 202. The air held by the groove forming portion 202 is referred to as an air layer 206, etc. The groove forming portion may also be referred to as a gas holding portion, an air holding portion, a microstructure, a microfabricated portion, etc.

[0032] The air layer of the groove formation portion 202 has compliance components C1 and C2. The compliance component C1 is a compliance component that the meniscus surface of the air layer has. The compliance component C2 is a compliance component that is due to the compressibility of the gas that fills the air layer. The compliance components C1 and C2 are also referred to as compliance C1, C2, etc.

[0033] The compliance C1 can be expressed by the following formula (3).

[0034]

number

[0035] In formula (3), γ is the surface tension of the liquid, and d is the inner diameter or short side of the groove. The unit of γ is, for example, mN / m, and the unit of d is, for example, m. Note that, for the sake of explanation, the shape of the groove is described as being cylindrical, but the shape of the groove is not particularly limited.

[0036] The meniscus is maintained by surface tension and its shape changes with pressure. Assuming that the surface of the meniscus is in equilibrium, the volume of the air layer formed in the groove determines the curvature of the meniscus. The pressure is determined by the surface tension γ of the liquid.

[0037] The compliance C2 can be expressed by the following formula (4).

[0038]

number

[0039] In formula (4), V is the volume of the air layer. γ is the surface tension of the liquid, as in formula (3). d is the inner diameter or short side of the groove, as in formula (3).

[0040] The formula for calculating compliance C2 can be introduced using the ideal gas equation of state and the Young-Laplace equation (the relational equation for pressure between the gas phase and the liquid phase). The premise for this introduction will be explained.

[0041] The definition of compliance C for a compressible object such as a gas is the ratio of the change in volume ΔW of the object to the change in pressure ΔP applied to the object, C=-ΔW / ΔP Equation (5) It can be expressed as:

[0042] When the volume of the air layer in the flow path is V and the pressure of the air layer is P, if the pressure of the air layer changes by ΔP and the volume of the air layer changes by ΔV, the compliance C2 of the air layer is given by the following equation (5). C2=-ΔV / ΔP Equation (6) It can be expressed as:

[0043] Here, let us assume that the air layer is an ideal gas. If the volume of the air layer is V, the pressure of the air layer is P, the number of moles of the air layer is n, the gas constant of an ideal gas is R, and the absolute temperature of the air layer is T, then from the gas state equation (PV=nRT), V=nRT / P Equation (7) holds true.

[0044] When n, R, and T are constants (when the temperature and the number of moles of gas are constant), differentiating equation (7) with respect to pressure P gives ΔV / ΔP=-nRT / P 2 =-V / P Equation (8) is obtained.

[0045] From equations (6) and (8), the compliance C2 of the air layer is given by C2=V / P formula (9) It is expressed as:

[0046] Here, the pressure P of the air layer corresponds to the pressure (Laplace pressure) at the interface between the air layer and the liquid in the flow channel, so using the Young-Laplace equation, P=γ(1 / R1+1 / R2) Equation (10) It can be expressed as:

[0047] In Equation (10), P is the pressure (Laplace pressure) at the interface between the air layer and the liquid, γ is the surface tension at the interface between the air layer and the liquid, and R1 and R2 are the radii of curvature of the cross-section orthogonal to the interface between the air layer and the liquid layer. Here, since the radius of curvature can be regarded as approximately the same as the inner diameter of the groove portion or the length d of the short side, R1 = R2 = d can be set. Therefore, P = 2γ / d Equation (11) can be regarded as. By applying Equation (11) to P in Equation (9), Equation (4) can be obtained.

[0048] In the above Equation (8), T is the temperature of the air layer 206. Strictly speaking, when a change in the pressure ΔP of the air layer causes a change in the volume ΔV of the air layer, a change in the temperature ΔT of the air layer due to the expansion and contraction of the air layer can be considered. However, since ΔT << T and it is cooled by the liquid in the flow path, ΔT is ignored and the temperature T of the air layer is used.

[0049] The compliance of the air layer formed in the groove portion can be expressed as the sum of compliance C1 and compliance C2. When a plurality of groove portions are arranged in the flow path, the compliance of the entire air layer provided in the flow path can be obtained by adding up compliance C1 and compliance C2 corresponding to the number of groove portions.

[0050] Figure 2 is a schematic diagram for explaining the compliance component of the air layer 206 in the groove forming portion 202. In the figure, the flow path member 212, the liquid flow path 210, the groove forming portion 202, the air layer 206, the contact portion 214, and the groove portion 204 are shown.

[0051] (A) is a diagram schematically showing the liquid flow path when the groove forming portion 202 is not formed. In order to indicate that the liquid 200 exists in the liquid flow path 210, the reference numerals in the figure are "200, 210".

[0052] 1B is a diagram showing an example in which a groove forming portion 202 is provided in a part of a liquid flow path 210. In the example shown, an air layer 206 held by the groove forming portion 202 has a curved surface that is convex toward the liquid 200 side (liquid flow path 210 side). As described in FIG. 1, in the microstructure formed by the groove forming portion 202, the liquid does not reach the bottom of the groove portion 204, and an air layer 206 is formed.

[0053] (C) is an enlarged view for illustrating the fluctuation of the air layer 206 in (B). In the air layer 206 of the groove formation portion 202, the position of the interface of the liquid 200 fluctuates as indicated by the double-headed arrow in the figure. The dashed line in the figure shows a schematic representation of the change in the position of the interface between the air layer 206 and the liquid 200. The fluctuation of the air layer 206 can attenuate the pressure fluctuation of the liquid 200 in the liquid flow path 210.

[0054] In the liquid ejection head, for example, when the liquid 200 is ejected, pressure fluctuations occur due to short-period vibrations Tc in the individual liquid chambers. The pressure fluctuations propagate through the liquid flow path 210 and adversely affect the ejection characteristics, etc. The groove formation portion 202 provided in the liquid flow path 210 causes the air layer 206 in the groove formation portion 202 to compress or rebound (expand) in response to the pressure fluctuations in the liquid flow path 210. This makes it possible to attenuate the pressure fluctuations of the liquid 200 in the liquid flow path 210.

[0055] The ejection characteristics are also called liquid ejection performance, and good ejection characteristics stabilize the size and speed of the droplets. In addition, the compression or rebound (expansion) of the air layer 206 in the above can be said to have a damping function. Therefore, the groove forming portion 202 can be said to have a damping function.

[0056] Next, an example of a case where the air layer 206 in the liquid chamber (inside the liquid flow path 210) is degassed (reduced in pressure) will be described. When the air layer 206 in the liquid flow path 210 is degassed, a gas layer (also referred to as a gas layer 208) is formed by vaporizing the liquid in the liquid flow path 210 in place of the air layer 206.

[0057] The state change when the air layer 206 is deaerated can be expressed as follows from Dalton's law of partial pressures: Air pressure P of the micromachined part = Air pressure P1 + Vapor pressure P2 of the air layer Equation (12)

[0058] That is, when the air pressure of the air layer 206 is reduced, the vapor pressure of the air layer increases, and a liquid air layer is formed in place of the degassed air layer. This phenomenon can also be confirmed by the fact that water in a vacuum (or reduced pressure environment) boils at low temperatures (approximately 23 to 50°C).

[0059] 3 is a diagram for explaining the gas layer 208. When the air layer 206 in the groove portion 204 of the groove forming portion 202 is degassed, the groove portion 204 of the groove forming portion 202 becomes a vacuum or negative pressure. As a result, as shown in FIG. 3(A), the liquid 200 in the liquid flow path 210 is vaporized, and the gas 200a of the liquid 200 is held in the groove portion 204, and the gas layer 208 is formed.

[0060] In the illustrated example, the liquid 200 curves from the liquid flow path 210 side toward the flow path member 212 side, and the liquid 200 forms a meniscus that is convex toward the flow path member 212 side. Fig. 3(B) shows in schematic form that the pressure fluctuation is attenuated by the formed meniscus. As in Fig. 2(C), in Fig. 3(B) as well, the pressure fluctuation in the liquid flow path 210 can be attenuated by the fluctuation of the gas layer 208.

[0061] The curvature direction of the interface between air layer 206 and liquid 200 is not limited to that shown in the figure, and may be convex toward the liquid 200 side, or may be convex toward the air layer 206 side. Similarly, the curvature direction of the interface between gas layer 208 and liquid 200 is not limited to that shown in the figure, and may be convex toward the liquid 200 side, or may be convex toward the gas layer 208 side.

[0062] Next, the fact that the contact angle of the groove formation portion 202 with respect to the liquid is 90° or more will be further described.

[0063] In this embodiment, at least a portion of the flow path member 212 is provided with a groove forming portion 202 having a plurality of grooves 204 formed by the recesses or protrusions, with at least a plurality of recesses or protrusions arranged on the liquid flow path 210 side. "At least a plurality of recesses or protrusions arranged on the liquid flow path 210 side" may also be expressed as "at least a plurality of recesses or protrusions arranged facing the liquid 200", etc.

[0064] As described above, when the contact angle θ of the groove formation portion 202 with respect to the liquid is 90° or more, the groove formation portion 202 exhibits liquid repellency with respect to the liquid 200, and an air layer 206 (which may be a gas layer 208, etc.) is formed in the groove portion 204, thereby damping pressure fluctuations within the liquid flow path 210.

[0065] In order to make the contact angle θ of the groove formation portion 202 with respect to the liquid equal to or greater than 90°, for example, there is a method of appropriately adjusting the interval, width, etc. of the groove portion 204. In order to appropriately adjust the interval, width, etc. of the groove portion 204, for example, the dimensions of the recessed or protruding portion that forms the groove portion 204 are appropriately adjusted.

[0066] When the average value of the interval between adjacent grooves 204 in one direction is a and the average value of the width of the grooves 204 in the one direction is b, a and b are 0 It is preferable that the following condition is satisfied. In this case, grooved portion 202 is more likely to exhibit the lotus effect (liquid repellency), and the contact angle θ of grooved portion 202 with respect to liquid is more likely to be 90° or more. The matters explained in relation to formula (2) above can be applied to formula (13) above.

[0067] ​The above formula (13) will be explained with reference to FIG. 4. The intervals between the grooves 204 in one direction are a1, a2,..., and the widths of the grooves 204 in the one direction are b1, b2, b3,.... The one direction is any direction, and may be, for example, the arrangement direction of the recesses or protrusions. Here, when there are multiple arrangement directions of the recesses or protrusions, the arrangement direction may be the direction in which the most adjacent recesses or protrusions are arranged. In other words, when there are multiple arrangement directions of the recesses or protrusions, an example of the one direction may be, for example, the direction in which the arrangement interval between the recesses or protrusions is smallest.

[0068] In this embodiment, the intervals between the grooves 204 may be the same or different for each groove 204. In this embodiment, the widths of the grooves 204 may be the same or different for each groove 204.

[0069] The average value of the intervals between adjacent grooves 204 in one direction is a, and the average value of the widths of the grooves 204 in the one direction is b. When calculating the average value, the number of intervals and widths of the grooves 204 is preferably large, but may be selected appropriately. The ratio of a to b (b / a) is also referred to as the aspect ratio b / a. The above formula (13) is also referred to as the aspect ratio relational formula.

[0070] In order to form more air layers 206 within a limited dimension, it is preferable that the aspect ratio b / a is larger. On the other hand, when the aspect ratio b / a is larger than 2, that is, when b / a>2, the mass and pressure of the liquid 200 present on the surface of the groove forming portion 202 may exceed the holding power of the groove forming portion 202 and may invade the groove portion 204. For this reason, by satisfying the above formula (13), the groove forming portion 202 can stably hold the air layer 206 more easily. As described above, the groove forming portion 202 may hold the gas layer 208, and although the following description is given using the air layer 206 as an example, the description also applies to the gas layer 208.

[0071] The interval between grooves 204 and the width of grooves 204 are each preferably 1 μm to 100 μm, and more preferably 10 μm to 100 μm. Also, the interval between grooves 204 and the width of grooves 204 are each preferably 1 μm to 100 μm, and more preferably 10 μm to 100 μm. By making the thickness 1 μm or more, the required machining precision of the concave or convex portions can be suppressed, and the concave or convex portions can be stably arranged. In addition, by making the thickness 1 μm or more, chipping in the flow path and damage due to friction and wear due to mechanical durability can be reduced. When the thickness is 100 μm or less, it is possible to prevent the lotus effect (liquid repellency) from decreasing, and it is possible to reduce the collapse of the air layer 206 due to a large pressure fluctuation. Also, it is possible to form the air layer 206 stably.

[0072] The average value a of the intervals between the grooves 204 and the average value b of the widths of the grooves 204 are preferably 1 μm or more and 100 μm or less, and more preferably 10 μm or more and 100 μm or less. In addition, the average value a of the intervals between the grooves 204 and the average value b of the widths of the grooves 204 are preferably both 1 μm or more and 100 μm or less, and more preferably 10 μm or more and 100 μm or less. From the viewpoint of improving the above-mentioned effects, it is preferable that the intervals between the grooves 204 are all 1 μm or more and 100 μm or less, it is preferable that the widths of the grooves 204 are all 1 μm or more and 100 μm or less, and it is particularly preferable that the intervals between the grooves 204 and the widths of the grooves 204 are all 1 μm or more and 100 μm or less.

[0073] In order to determine whether the grooved portion 202 exhibits liquid repellency, the contact angle θ may be determined by measuring the grooved portion 202 using the liquid 200, or cosθ may be determined by the above formula (1). In the above formula (1), θa is the static contact angle between the liquid and the surface of the material A, and θb is the static contact angle between the liquid and the surface of the material B. In the grooved portion 202, θa is the contact angle between the flow path member 212 and the liquid 200, and θb is the contact angle between the air layer 206 (which may be the gas layer 208, etc.) and the liquid 200. θa and θb can be determined as shown in FIG. 6, which will be described later. The above formula (1) may be referred to as a formula for the contact angle, and the above formula (13) may be referred to as a relational formula for the aspect ratio.

[0074] The depth h of the grooves 204 is not particularly limited and may be changed as appropriate. The grooves 204 may be the same or different.

[0075] From the viewpoint of maintaining the air layer 206, it is preferable that the contact angle θ of the groove formation portion 202 is large, and when the contact angle θ is 90° or more, the groove formation portion 202 can stably maintain the air layer 206. On the other hand, if the contact angle θ is too large, large air bubbles may be trapped in the groove portion 204. In this case, the air bubbles exposed from the groove portion 204 may obstruct the flow of the liquid 200 in the liquid flow path 210. For this reason, the contact angle θ is preferably 140° or less, and more preferably 110° or less.

[0076] 5(A) is a diagram showing a schematic example of a case where the contact angle θ is greater than 110°. When the contact angle θ is greater than 110°, the air layer 206 is exposed to a greater extent, and the air layer 206 protrudes toward the liquid flow path 210 from the surface of the groove forming portion 202. In the figure, the protruding portion is indicated by the symbol 206a. When the air layer 206 is exposed to a greater extent toward the liquid flow path 210, the flow of the liquid 200 in the liquid flow path 210 may be hindered. For this reason, it is more preferable that the contact angle θ satisfies 90°≦θ≦110°, and in this case, the retention force of the air layer 206 is more stable.

[0077] 5(B) is a schematic diagram for explaining an example in which the interval a1 of the grooves 204 and the width b1 of the grooves 204 are both large, and is a diagram that typically shows an example in which a1 and b1 are both 100 μm or more. Note that in the figure, they are denoted as a1 and b1 to distinguish them from the average interval a and the average width b.

[0078] 5(B) shows an example in which the contact angle θ is 90° or more, satisfying the above formula (13), but the interval a1 and width b1 of the groove portion 204 are both greater than 100 μm. In this case, the lotus effect (retentive force) can be obtained, but if a large pressure change occurs, the air layer 206 may break down. For this reason, it is particularly preferable that the contact angle θ is 90° or more, satisfying the above formula (13), and that the interval and width of the groove portion 204 are both 100 μm or less.

[0079] Next, a method for measuring the contact angle will be described. The contact angles θ and θa are measured, for example, by the sessile drop method. The sessile drop method shall conform to JIS R 3257. The contact angle θb is measured, for example, by the air bubble method. Since the air bubble method is not specified in industrial standards such as JIS or ISO, it shall conform to the handling of the measuring device. It is assumed that the contact angles θ, θa, and θb are static contact angles, and in this specification, the static contact angles are also referred to simply as contact angles.

[0080] 6A is a schematic diagram for explaining a measurement example of contact angles θ and θa, showing a measurement example by the sessile drop method. Liquid 200 is placed on flow path member 212, and measurement is performed using syringe 216.

[0081] 6(B) is a schematic diagram for explaining a measurement example of the contact angle θb, showing an example of measurement by the air bubble method. In a container filled with liquid 200, gas 201 is brought into contact with flow path member 212, and measurement is performed using syringe 216. Examples of gas 201 include air in air layer 206 and gas in gas layer 208. When air layer 206 is formed in groove formation portion 202, measurement may be performed using air.

[0082] As can be seen from the above, in this embodiment, the contact angle θ of the groove forming portion 202 may be determined by measuring the flow path member 212 in which the groove forming portion 202 is provided using the sessile drop method (e.g., Figure 6(A)), or may be determined using the above formula (1).

[0083] When determining the contact angle θ of the groove formation portion 202 using the above formula (1), for example, the following procedure is followed. The contact angle θa is measured by the sessile drop method (for example, FIG. 6(A)), and the contact angle θb is measured by the bubble method (for example, FIG. 6(B)). In addition, the average value a of the distance between adjacent groove portions 204 in one direction and the average value b of the width of the groove portions 204 in the one direction are determined. These a and b do not have to be actually measured, and may be design values. By applying the thus determined θa, θb, a, and b to the above formula (1), the contact angle θ of the groove formation portion 202 can be determined.

[0084] When the contact angle θ of the groove formation portion 202 is obtained using the above formula (1), it can be obtained from the material of the flow path member 212, the dimensions of the groove portion 204, etc., even if the groove formation portion 202 is not actually formed. This has the advantage that the liquid repellency of the groove formation portion 202 and the configuration of the flow path member 212, etc. can be considered at the design stage before the liquid ejection head is manufactured.

[0085] The material of the flow path member 212 can be appropriately selected, and materials used for general flow path members can be used. In addition, substrate (wafer) materials used in general semiconductor manufacturing can be used. For example, resins such as PPS (polyphenylene sulfide), SUS, other metals, etc. In addition, substrate (wafer) materials using silicon, germanium, gallium arsenide, and compounds containing these can be used.

[0086] Next, the groove formation portion 202 and the liquid flow path 210 will be described with some examples. 7A and 7B are diagrams for explaining an example of the groove forming portion 202 when the liquid flow path 210 has a cylindrical shape. In the example shown here, the shape of the part of the liquid flow path 210 where the groove forming portion 202 is provided is cylindrical. In this example, the shape of the part of the liquid flow path 210 where the groove forming portion 202 is provided is cylindrical, but this embodiment is not limited to this. For example, the entire shape of the liquid flow path 210 may be cylindrical, or the shape of the part of the liquid flow path 210 other than that shown in the figure may not be cylindrical.

[0087] In addition, in the illustrated example, the flow path member 212 is cylindrical, but this example is not limited to this. For example, this example also includes the case where the flow path member 212 is rectangular parallelepiped shaped and the liquid flow path 210 is cylindrical.

[0088] Fig. 7A shows an example in which the groove direction of groove portion 204 of groove formation portion 202 is the circumferential direction of liquid flow path 210. Arrows in the figure typically indicate the direction in which liquid 200 flows. Fig. 7A(A) is a schematic perspective view of the main parts, and Fig. 7A(B) is a schematic plan view of flow path member 212 cut in half and viewed from the liquid flow path 210 side to the flow path member 212 side.

[0089] In the example shown in Fig. 7A, the direction of groove portion 204 is the circumferential direction of liquid flow path 210. The groove direction of groove portion 204 may be referred to as the longitudinal direction of groove portion 204, and when the bottom of groove portion 204 is viewed in a plane, it can also be said that the direction of groove portion 204 is the longitudinal direction of the bottom. Also, in this example, it can also be said that the recesses or protrusions forming groove portion 204 are arranged in the direction in which liquid 200 flows. In the case of Fig. 7A, by providing many recesses and protrusions parallel to the short sides of the flow path, there is an advantage that even if some air layers break (liquid enters the recesses), the impact on the whole is small.

[0090] In the example shown in Fig. 7B, the groove direction of groove portion 204 is the direction in which liquid 200 flows. Fig. 7B(A) is a schematic perspective view of the main part, and Fig. 7B(B) is a schematic plan view of flow path member 212 cut in half and viewed from the liquid flow path 210 to the flow path member 212. In this example, it can be said that the recesses or protrusions forming groove portion 204 are arranged in the circumferential direction of liquid flow path 210. In the case of Fig. 7B, each recess or protrusion is arranged longer in parallel to the long side of the flow path, so that the required compliance can be ensured with fewer cuts (processing).

[0091] The liquid flow path 210 is not limited to a cylindrical shape, and may be, for example, a tubular shape having one flat side. Fig. 8 is a diagram for explaining another example of the groove forming portion 202 and the liquid flow path 210. As shown in Fig. 8(A), the liquid flow path 210 may be in the shape of a rectangular parallelepiped.

[0092] In addition to the above, the liquid flow path 210 may have a shape as shown in Fig. 8(B). In the example shown here, the liquid flow path 210 is substantially cylindrical, but has one flat side. In addition to the above, the liquid flow path 210 may have a triangular prism shape as shown in Fig. 8(C).

[0093] In the example shown in Fig. 8, the location where the groove forming portion 202 is provided can be appropriately selected, and it is preferable that the groove forming portion 202 is provided on one or more of the flat surfaces. When the groove forming portion 202 is formed on a flat surface, processing is easy. However, this is not limited to this, and the groove forming portion 202 may be provided on a circumferential portion of the liquid flow path 210 as shown in the examples of Figs. 7A and 7B. For example, the groove forming portion 202 may be provided on a circumferential portion (curved portion) of Fig. 8(B).

[0094] There is no particular limitation on the location where the groove forming portion 202 is provided, and it may be one location or multiple locations. For example, in Fig. 8(A), the groove forming portion 202 is illustrated on only one surface, but this is not limiting, and the groove forming portion 202 may be provided on the other surfaces.

[0095] 9 is a diagram showing an example of a case where groove forming portions 202 are provided on multiple surfaces, and this example is an example where groove forming portions 202 are provided on two adjacent surfaces. (A) is a diagram for explaining that groove forming portions 202 are provided on two surfaces, (B) is an enlarged view of a main portion of (A), and (C) is a diagram for explaining the relationship in length in (B).

[0096] When groove formation portion 202 is provided on two adjacent surfaces, it is preferable to space groove formation portion 202 to a certain extent from intersection P1 of the two surfaces. Intersection P1 of the two surfaces is also called a curved portion. In the illustrated example, the two surfaces are flat, but this is not limiting, and the explanation given here also applies to the case where the two surfaces are curved.

[0097] As shown in (B), the groove forming portion provided on one surface is indicated by the reference symbol 42, and the groove forming portion provided on the other surface is indicated by the reference symbol 202'. The distance from the intersection P1 of the two surfaces (hereinafter also simply referred to as the intersection P1) to the ends of the groove forming portions 202, 202' is indicated as c on one surface, and as c' on the other surface. c is the distance from the intersection P1 to the end P2 of the groove forming portion 202, and c' is the distance from the intersection P1 to the end P3 of the groove forming portion 202'. It is preferable that c and c' are sufficiently long so that an unexpected uneven pattern is not formed.

[0098] In order to provide the groove forming portions 202 and 202′ at positions sufficiently distant from the intersection point P1, c>a and c'>a' Equation (14) It is preferable that the above formula (14) be expressed as follows: a is the average value of the spacing between groove portions 204 in groove formed portion 202, and a' is the average value of the spacing between groove portions 204 in groove formed portion 202'. For the sake of explanation, in the drawing, the spacing between groove portions 204 in groove formed portion 202 is represented by a1, a2..., and the spacing between groove portions 204' in groove formed portion 202' is represented by a1', a2'....

[0099] In (B), the intersection point P1, the end P2 of the grooved portion 202, and the end P3 of the grooved portion 202' are shown. Also, as shown in (B), a straight line is drawn between the end P2 and the end P3, and a perpendicular line H is drawn from the intersection point P1 to the line P2P3. In this case, the angle between the line P1P2 and the perpendicular line H is α, and the angle between the line P1P2 and the line P1P3 is β. Also, the intersection point between the line P2P3 and the perpendicular line H is the intersection point P4.

[0100] In (C), the length of P2P4 and the length of P3P4 are explained. As shown in the figure, the length of P2P4 is c×cos(90°-α), and the length of P3P4 is c'×cos(90°-(β-α)). When groove formation portions 202, 202' are provided on two adjacent surfaces, respectively, it is preferable that the relationship be as shown in the above formula (14), and it is preferable that the above formula (14) is modified to obtain the following formula (14)'. c+c'>a+a' Equation (14)'

[0101] For the above formula (14)', when the length of P2P4 and the length of P3P4 are used, it is preferable that the relationship of the following formula (15) is satisfied. c×cos(90°-α)+c'×cos(90°-(β-α))>a+a' Equation (15)

[0102] In other words, when groove-forming portions 202, 202' are provided on two adjacent surfaces, respectively, it is preferable to design the liquid flow path 210 and the groove-forming portions 202, 202' so as to satisfy the above formula (15). If the line P2P3 is a curve and the intersection point P1 cannot be identified, the midpoint of the line P2P3 may be set as the intersection point P1. Alternatively, if the line P2P3 is a curve and the intersection point P1 cannot be identified, an arbitrary point may be set as the intersection point P1 using a tangent to the contact surface.

[0103] Next, an example of a method for forming the groove formation portion 202 will be described. 10 is a diagram for explaining an example of a method for forming the groove formation portion 202. (A) is an unprocessed flow path member 212, (B) is an example in which the groove formation portion 202 is formed by arranging a plurality of recesses in the flow path member 212, and (C) is an example in which the groove formation portion 202 is formed by arranging a plurality of protrusions in the flow path member 212. In (B) and (C), the groove formation portion 202 is provided on the liquid flow path 210 side of the flow path member 212.

[0104] 1B is an example in which a plurality of recesses are arranged to form groove formation portion 202. In order to arrange a plurality of recesses, for example, an etching method, a dicing method, or the like is used. 1C is an example in which a plurality of convex portions are arranged to form the groove formation portion 202. In order to arrange a plurality of convex portions, for example, a coating method, a transfer method, or the like is used.

[0105] In this way, the groove portion 204 may be formed by providing a plurality of recesses in the flow path member 212, or the groove portion 204 may be formed by providing a plurality of protrusions in the flow path member 212. As shown in the figure, when the groove forming portion 202 is formed by providing a plurality of recesses, the recesses become the groove portion 204. When the groove forming portion 202 is formed by providing a plurality of protrusions, the groove portion 204 is formed between the protrusions. When a protrusion is provided, the material of the protrusion may be the same as or different from the material of the flow path member 212.

[0106] Next, a further explanation will be given of the compliance of the air layer 206 (which may be the gas layer 208, etc.) held in the groove portion 204 of the groove forming portion 202. As illustrated and explained in Fig. 2(C) and Fig. 3(B), the air layer 206 held in the groove portion 204 of the groove forming portion 202 deforms, thereby making it possible to attenuate pressure fluctuations in the liquid flow path 210.

[0107] The pressure vibrations occurring within the liquid flow path 210 are also referred to as residual vibrations. Examples of residual vibrations include vibrations caused by driving the pressure generating means, vibrations caused by ejecting liquid, vibrations propagated to other individual liquid chambers via a common liquid chamber, and vibrations caused when liquid is supplied to the liquid flow path 210. Furthermore, the pressure vibrations occurring within the liquid flow path 210 can also be classified into vibrations caused by the liquid chamber natural period (Tc) and refill period vibrations.

[0108] The liquid chamber natural period (Tc) corresponds to the natural vibration period of the pressure vibrations that occur in the nozzle and pressure chamber (the part of the individual liquid chamber where pressure is applied). It is generally called the Helmholtz period. The natural vibration period of this individual liquid chamber is a short vibration of about a few μs. It is measured as the vibration of the nozzle meniscus.

[0109] The "refill" in refill periodic vibration means that droplets ejected from the nozzle are supplied (refilled) from the common liquid chamber to the individual liquid chamber. Refill periodic vibration is a pressure vibration that occurs in the flow path including not only the individual liquid chambers but also the common liquid chamber. It is a vibration with a period longer than the vibration period of the individual liquid chambers, ranging from several μs to several hundred μs. Like the vibration due to the liquid chamber's natural period, it is measured as a vibration of the nozzle meniscus.

[0110] In this embodiment, these pressure vibrations with different periods can be damped, which has an excellent advantage.

[0111] The compliance C of the air layer 206 has a compliance component C1 due to the deformation of the meniscus on the gas surface and a compliance component C2 due to the elasticity of the gas. From the above formulas (3) and (4), the compliance C of the air layer 206 can be expressed as follows:

[0112]

number

[0113] In the example shown in Table 1 below, the compliance C of the air layer 206 was actually calculated using the above formula (16).

[0114] [Table 1]

[0115] In the case of the example shown in Table 1, when C, C1, and C2 are calculated using Table 1 and the above formula (16), the compliance C obtained from the dimensions of the groove portion 204 (1.5×1.5×1.5 μm) is 36.5 μm. 3 / Pa. To add to that, C=C1+C2 =1.71+34.8[μm 3 / Pa] =36.5[μm 3 / Pa]

[0116] In this way, it is possible to find the compliance C of the air layer 206 from the dimensions of the groove portion 204, and it is preferable to design the groove formation portion 202 taking into consideration the configuration of the liquid 200 to be used, etc. It is also possible to find the compliance C of the air layer 206 in the fabricated groove formation portion 202.

[0117] Next, an example of the nozzle and the pressure generating means will be described. The liquid ejection head of this embodiment comprises a nozzle for ejecting liquid, a flow path member forming a liquid flow path communicating with the nozzle, and a pressure generating means for varying the pressure of the liquid in the liquid flow path.

[0118] 11 is a diagram for explaining an example of a nozzle and a pressure generating means. In the figure, a liquid flow path 210, a groove forming portion 202, a nozzle 11, and a pressure generating means 220 are shown. The pressure generating means 220 changes the pressure of the liquid 200 in the liquid flow path 210, and the liquid 200 is ejected from the nozzle 11.

[0119] As the pressure generating means 220, for example, a piezoelectric actuator can be used, and the piezoelectric actuator has, for example, electrodes, PZT (lead zirconate titanate), a vibration plate, etc. The pressure generating means 220 may be called a drive unit, etc. In this example, a drive circuit (not shown) is provided. The pressure generating means is not limited to a piezoelectric actuator, and any means can be used as long as it is a means for varying the pressure of the liquid 200 in the liquid flow path 210. For example, an electrostatic actuator using electrostatic force, a heater that applies heat to the liquid 200 to vaporize it, etc. can be exemplified.

[0120] The locations where the groove forming portions 202 are provided, the number of the groove forming portions 202, the number of the grooves 204, etc. are not limited to those shown in the figure, and can be changed as appropriate.

[0121] <Second embodiment> Next, another embodiment of the present invention will be described. In this embodiment, the groove formation portion 202 includes a liquid-repellent layer that is liquid-repellent to the liquid 200. The liquid-repellent layer may also be called a liquid-repellent film, a water-repellent film, a liquid-contacting film, or the like.

[0122] Fig. 12 is a diagram for explaining this embodiment, and shows an example in which a liquid-repellent film 218 is formed in the example shown in Fig. 10. Fig. 12B shows an example in which a plurality of recesses are provided to form grooves 204, and liquid-repellent film 218 is formed between adjacent grooves 204. Fig. 12C shows an example in which a plurality of protrusions are provided to form grooves 204, and liquid-repellent film 218 is formed on the protrusions. Note that, although Fig. 12C shows liquid-repellent film 218 also between protrusions, the present invention is not limited to this, and liquid-repellent film 218 does not necessarily have to be formed between protrusions.

[0123] By including a liquid-repellent layer in the groove forming portion 202, liquid that has entered the groove due to the air layer being broken can be repelled (pushed out) into the flow path. Therefore, even if the air layer breaks in the flow path, a restoring force can be obtained. Therefore, the air layer can be stabilized against impacts, etc.

[0124] The liquid-repellent film 218 is provided at a location where the groove formation section 202 and the liquid 200 can come into contact with each other, and is provided on the liquid flow path 210 side. The liquid-repellent film 218 is provided, for example, on the surface of the groove formation section 202.

[0125] The method for forming the liquid-repellent film 218 can be appropriately selected, and for example, a method for forming the film by coating a film material can be mentioned.

[0126] <Third embodiment> Next, another embodiment of the present invention will be described. An example of the liquid flow path has been described in the above-mentioned first embodiment. In this embodiment, the configuration of the liquid flow path, the arrangement and number of groove formation parts, etc. are different from those in the above-mentioned embodiment.

[0127] In this embodiment, a plurality of nozzles 11 and pressure generating means 220 are provided. The liquid flow path 210 has a plurality of individual liquid chambers 222 that communicate with the plurality of nozzles 11, respectively, and a common liquid chamber 224 that communicates with the plurality of individual liquid chambers 222. The common liquid chamber 224 communicates with the individual liquid chambers 222 via a fluid resistance portion 226 provided for each individual liquid chamber 222. The liquid 200 flows through the common liquid chamber 224 and the individual liquid chambers 222 in this order. The pressure generating means 220 varies the pressure of the liquid in the individual liquid chambers 222. The groove forming portion 202 is provided in the liquid flow path 210 upstream of the fluid resistance portion 226.

[0128] Fig. 13A is a schematic diagram for explaining this embodiment. Fig. 13A(A) is a schematic cross-sectional diagram showing one nozzle 11 and one pressure generating means 220. (B) is a schematic plan view. In (A) and (B), the groove forming portion 202 is omitted.

[0129] As shown by the arrows in Figure 13A(A), the liquid 200 flows from the common liquid chamber 224 to the individual liquid chamber 222, where pressure is applied by the pressure generating means 220, and the liquid 200 is ejected from the nozzle 11. The dashed line in the figure shows a schematic boundary between the common liquid chamber 224 and the individual liquid chamber 222. The individual liquid chamber 222 has a fluid resistance section 226, and for example, the width of the flow path is narrowed in the fluid resistance section 226. Note that to indicate that the individual liquid chamber 222 and the common liquid chamber 224 are part of the liquid flow path 210, the reference numerals in the figure are written as 222 (210) and 224 (210).

[0130] In this embodiment, the groove formation portion 202 is provided in the liquid flow path 210 upstream of the fluid resistance portion 226. The liquid flow path 210 upstream of the fluid resistance portion 226 includes a part of the individual liquid chamber 222 and the common liquid chamber 224, as shown in the figure.

[0131] 13A(B) is a plan view for explaining the flow of liquid in (A) and is a schematic diagram for explaining the positional relationship between the individual liquid chambers 222 and the common liquid chamber 224. The arrows in the figure show the flow of liquid. As shown in the figure, the liquid in the common liquid chamber 224 flows into each individual liquid chamber 222. Although the fluid resistance section 226, the nozzle 11, and the pressure generating means 220 are not shown in (B), the liquid in the individual liquid chambers 222 downstream of the fluid resistance section 226 is discharged from the nozzle 11 by applying pressure to it by the pressure generating means 220.

[0132] In addition, in the individual liquid chamber 222, a portion downstream of the fluid resistance portion 226 and to which pressure is applied to the liquid by the pressure generating means 220 may also be referred to as a pressure chamber.

[0133] 13B(A) is a schematic cross-sectional view for explaining an example of the arrangement of the groove forming portion 202 in this embodiment. In addition, (A) shows a schematic diagram of pressure vibrations occurring in the liquid flow path 210, and (B) is an enlarged schematic diagram for explaining a schematic diagram of an example of a mechanism for damping the pressure vibrations occurring in the liquid flow path 210.

[0134] 13B(A) shows pressure vibrations (solid lines) generated by the pressure generating means 220 and pressure vibrations (dashed lines) caused by ejection in an individual liquid chamber 222 downstream (toward the nozzle 11) of the fluid resistance portion 226. Such pressure vibrations pass through the fluid resistance portion 226 and propagate to the liquid flow path 210 upstream of the fluid resistance portion 226. If the groove formation portion 202 were not provided, the pressure vibrations would propagate to other individual liquid chambers 222 via the common liquid chamber 224, affecting the ejection characteristics.

[0135] In this example, as shown in FIG. 13B(A), groove forming portions 202a to 202e are provided in the liquid flow path 210. As shown in (B), the air layer 206 held in the groove portion 204 of the groove forming portion 202 can damp the pressure vibration generated in the liquid flow path 210. As described above, for example, the pressure vibration can be damped by the compliance of the air layer 206. Also, as described above, the vibration due to the liquid chamber natural period (Tc) and the refill period vibration can be damped, and pressure vibrations with different periods can be damped. In this embodiment, too, the pressure fluctuation due to the residual vibration can be reduced, and the propagation of the residual vibration to adjacent nozzles can be suppressed.

[0136] In this embodiment, the number, arrangement, etc. of the groove forming portions 202 can be appropriately selected. As shown in Fig. 13B(A), when a plurality of groove forming portions 202 are provided, the pressure vibration generated in the liquid flow path 210 can be further attenuated. The groove forming portion 202b is provided so as to straddle the individual liquid chamber 222 and the common liquid chamber 224, but the groove forming portion 202b may be provided in this manner.

[0137] Since the common liquid chamber 224 has a flow path with a width greater than that of the individual liquid chambers 222, providing the groove formation portion 202 in the common liquid chamber 224 has the advantage of being easier to manufacture than providing the groove formation portion 202 in the individual liquid chambers 222.

[0138] 13B(A) illustrates the intersection point P1. As described in FIG. 9, when groove forming portions 202 are provided on two adjacent surfaces, it is preferable to provide the groove forming portions 202 away from the intersection point P1.

[0139] It is preferable that the groove forming portion 202 is provided at a position at least twice the average width b of the groove portion 204 in one direction from the fluid resistance portion 226. In this way, when the groove forming portion 202 is provided at a position away from the fluid resistance portion 226, it is possible to suppress a decrease in the filling property of the liquid from the fluid resistance portion 226 into the pressure chamber.

[0140] The groove formation portion 202 is preferably disposed at a position 100 μm or more away from the fluid resistance portion 226. This can prevent a decrease in the ability of the liquid to be filled from the fluid resistance portion 226 into the pressure chamber.

[0141] In this embodiment, the groove forming portion 202 is provided in the liquid flow path 210 upstream of the fluid resistance portion 226. However, the present invention does not exclude a configuration in which the groove forming portion 202 is provided in the liquid flow path 210 downstream of the fluid resistance portion 226. When the groove forming portion 202 is provided in the liquid flow path 210 downstream of the fluid resistance portion 226, the groove forming portion 202 is located close to the pressure generating means 220, so that the pressure fluctuation caused by the pressure generating means 220 is easily attenuated. On the other hand, when the groove forming portion 202 is provided in the liquid flow path 210 upstream of the fluid resistance portion 226, the effect of reducing residual vibrations including other pressure vibrations, not limited to pressure fluctuations caused by the pressure generating means 220, is improved. From this viewpoint, it is preferable that the groove forming portion 202 is provided in the liquid flow path 210 upstream of the fluid resistance portion 226, as in this embodiment.

[0142] <Fourth embodiment> Next, another embodiment of the present invention will be described. In this embodiment, the configuration of the liquid flow path is different from that of the third embodiment, and the liquid ejection head of this embodiment is a circulation type liquid ejection head. However, the matters described in the above embodiment are also applicable to this embodiment unless otherwise specified.

[0143] In this embodiment, a plurality of nozzles 11 and pressure generating means 220 are provided. The liquid flow path 210 has individual liquid chambers 222 each communicating with the plurality of nozzles 11, a supply side common liquid chamber 230 communicating with the plurality of individual liquid chambers 222, and a recovery side common liquid chamber 232 communicating with the plurality of individual liquid chambers 222. The supply side common liquid chamber 230 communicates with the individual liquid chambers 222 via a supply side fluid resistance portion 234 provided for each individual liquid chamber 222, and the recovery side common liquid chamber 232 communicates with the individual liquid chambers 222 via a recovery side fluid resistance portion 236 provided for each individual liquid chamber 222. The liquid 200 flows through the supply side common liquid chamber 230, the individual liquid chamber 222, and the recovery side common liquid chamber 232 in this order. The pressure generating means 220 changes the pressure of the liquid in the individual liquid chamber 222. The groove formation section 202 is provided in at least one of the liquid flow path 210 upstream of the supply side fluid resistance section 234 and the liquid flow path 210 downstream of the recovery side fluid resistance section 236 .

[0144] 14A is a schematic diagram for explaining this embodiment. (A) is a schematic cross-sectional view showing one nozzle 11 and one pressure generating means 220. (B) is a plan view for typically explaining the flow of liquid in (A), and is a schematic diagram for explaining the positional relationship of the supply side common liquid chamber 230, the individual liquid chamber 222, and the recovery side common liquid chamber 232. (B) does not show the groove formation portion 202. For example, as indicated by the arrow in the figure, the liquid 200 flows in the order of the supply side common liquid chamber 230, the individual liquid chamber 222, and the recovery side common liquid chamber 232.

[0145] In the example shown in FIG. 14A(A), groove forming portions 202a-202h are provided, and the illustrated example can be said to be a particularly preferable example. The groove forming portions 202a-202e are groove forming portions 202 provided in the liquid flow path 210 upstream of the supply side fluid resistance portion 234. The groove forming portions 202f-202h are groove forming portions 202 provided in the liquid flow path 210 downstream of the recovery side fluid resistance portion 236. The effect of the present invention can be obtained by providing one of the groove forming portions 202a-202h. When the groove forming portions 202 are provided in both the liquid flow path 210 upstream of the supply side fluid resistance portion 234 and the liquid flow path 210 downstream of the recovery side fluid resistance portion 236, the effect of the present invention is improved.

[0146] When groove forming portions 202 are provided in both the liquid flow path 210 upstream of the supply side fluid resistance portion 234 and the liquid flow path 210 downstream of the recovery side fluid resistance portion 236, pressure fluctuations can be attenuated on both the supply side and the recovery side.

[0147] Fig. 14B is a diagram for typically explaining pressure vibration. (A) is a schematic cross-sectional view also corresponding to Fig. 14A(A), and (B) is a schematic plan view also corresponding to Fig. 14A(B). (C) is an enlarged schematic view for typically explaining an example of a mechanism for damping pressure vibration generated in the liquid flow channel 210.

[0148] 14B(A) shows pressure vibrations (solid lines) generated by the pressure generating means 220 and pressure vibrations (dashed lines) due to ejection in the individual liquid chamber 222 downstream (toward the nozzle 11) of the fluid resistance portion 226. Such pressure vibrations pass through the supply side fluid resistance portion 234 and propagate to the supply side common liquid chamber 230. In addition, such pressure vibrations pass through the recovery side fluid resistance portion 236 and propagate to the recovery side common liquid chamber 232. If the groove formation portion 202 is not provided, the pressure vibrations propagate to the other individual liquid chambers 222 via the supply side common liquid chamber 230 and the recovery side common liquid chamber 232, affecting the ejection characteristics.

[0149] In this example, as shown in FIG. 14A(A) and FIG. 14B(A), groove forming portions 202a-h are provided in the liquid flow path 210. As shown in (C), the air layer 206 held in the groove portion 204 of the groove forming portion 202 can attenuate the pressure vibration generated in the liquid flow path 210. As described above, for example, the pressure vibration can be attenuated by the compliance of the air layer 206. Also, as described above, the vibration due to the liquid chamber natural period (Tc) and the refill period vibration can be attenuated, and pressure vibrations with different periods can be attenuated. In this embodiment, too, the pressure fluctuation due to the residual vibration can be reduced, and the propagation of the residual vibration to adjacent nozzles can be suppressed.

[0150] 14A and 14B, the intersection point P1 is omitted from the illustration. The above description of the intersection point P1 can also be applied to this example.

[0151] <Fifth embodiment> Next, another embodiment of the present invention will be described. In the present invention, the recesses or protrusions may be arranged in one direction to form the groove formation portion 202, or the recesses or protrusions may be arranged in multiple directions to form the groove formation portion 202. Here, this embodiment will be described using an example in which the recesses or protrusions are arranged in two directions to form the groove formation portion 202.

[0152] 15(A) and (B) are schematic plan views for explaining an example of the groove formation portion 202 in this embodiment. (A) is a diagram showing an example in which the groove formation portion 202 is formed by providing a plurality of recesses to form the groove portion 204. (B) is a diagram showing an example in which the groove formation portion 202 is formed by providing a plurality of protrusions to form the groove portion 204. In the example shown in the figure, the recesses and protrusions are arranged in two directions to form the groove portion 204.

[0153] When the recesses or protrusions are arranged in multiple directions, more air layers 206 can be formed with the same dimensions compared to when the recesses or protrusions are arranged in one direction.

[0154] In (A), adjacent grooves 204 may or may not be connected to each other. Air layers 206 (which may be gas layers 208, etc.) held in grooves 204 may or may not be connected to other air layers 206.

[0155] When the recesses or protrusions are arranged in multiple directions, the groove forming portion 202 satisfies the requirement that the contact angle with respect to the liquid 200 is 90° or more in at least one of the directions in which the recesses or protrusions are arranged. This allows the groove forming portion 202 to exhibit liquid repellency even when the recesses or protrusions are arranged in multiple directions, and allows the air layer 206 (which may be a gas layer 208, etc.) to be held in the groove portion 204.

[0156] When the recesses or protrusions are arranged in multiple directions, it is preferable that the above formula (13) is satisfied in at least one direction. In this case, even when the recesses or protrusions are arranged in multiple directions, the grooved portion 202 is more likely to exhibit liquid repellency. When the recesses or protrusions are arranged in multiple directions, it is even more preferable that the above formula (13) is simultaneously satisfied in all directions in which the recesses or protrusions are arranged. In this case, the grooved portion 202 is more likely to exhibit liquid repellency, and the air layer 206 is more likely to be retained.

[0157] 15(A) and (B) are schematic plan views, but may be curved surfaces. Therefore, the examples shown in Fig. 15(A) and (B) are also applicable to cylindrical liquid flow paths 210 as shown in Fig. 7A and Fig. 7B, and other cylindrical flow path members 212, etc.

[0158] When the recesses or protrusions are arranged in multiple directions, the contact angle θ is 90° or more in a cross section in at least one of the directions in which the recesses or protrusions are arranged. A supplementary explanation of the contact angle of 90° or more in at least one direction will be given with reference to FIG. 16. FIG. 16 is a diagram showing the example of FIG. 15(A), and shows dashed lines s1 to s6 as candidates for a cross section in the arrangement direction of the recesses. The recesses in this example are arranged in, for example, direction 1 (up and down direction on the paper) and direction 2 (left and right direction on the paper). It can be said that the recesses are also arranged in a diagonal direction on the paper, but this direction need not be considered here.

[0159] Consider direction 1 for example. It is preferable that the groove formation portion 202 has a contact angle with respect to the liquid of 90° or more in all cross sections along direction 1 including dashed lines s1 to s3, but it is sufficient that the contact angle is 90° or more in at least one cross section along direction 1 including dashed lines s1 to s3. For example, when the contact angle is 90° or more in the cross section along dashed line s1, it can be said that the contact angle θ is 90° or more in at least one cross section along the direction in which the recesses or protrusions are arranged. When the contact angle is 90° or more in direction 1, direction 2 does not have to have a contact angle of 90° or more.

[0160] Similarly, consider direction 2. Even if the contact angle does not satisfy the requirement of 90° or more in direction 1, the present invention is included if the contact angle satisfies the requirement of 90° or more in direction 2. As with direction 1, for example, when the contact angle satisfies the requirement of 90° or more in a cross section taken along dashed line s4, it can be said that the contact angle θ is 90° or more in a cross section in at least one of the directions in which the recesses or protrusions are arranged.

[0161] Sixth embodiment Next, another embodiment of the present invention will be described. In the above fifth embodiment, the volumes of the grooves 204 are the same or approximately the same, but the present invention is not limited to this, and the shapes and volumes of the grooves 204 may be different. In this embodiment, an example in which the shapes and volumes of the grooves 204 are different will be described.

[0162] 17(A) and (B) are schematic plan views for explaining an example of this embodiment. In the example shown in (A), a plurality of circular recesses are provided, and furthermore, a triangular recess and a recess in the shape of an x ​​are provided. In the example shown in (B), a plurality of triangular recesses are provided, and furthermore, a rectangular recess is provided. In (A) and (B), the provided recesses are grooves 204. Thus, in this embodiment, the shapes and volumes of the grooves 204 are different.

[0163] When the volumes of the grooves 204 are different, there are locations in the groove formation portion 202 where the volumes of the air layers 206 (which may be gas layers 208, etc.) held by the grooves 204 are different. This causes differences in the compliance of the air layers 206, and the groove formation portion 202 has different resonance frequencies according to the compliance. This makes it possible to attenuate pressure fluctuations in the liquid flow path 210 more effectively by using compliance with multiple resonance frequencies (resonance frequency bands). Therefore, in this embodiment, the frequency band of pressure fluctuations that can be attenuated can be expanded, and pressure fluctuations can be attenuated more efficiently.

[0164] Furthermore, when the shape or volume of the groove portion 204 is different, pressure fluctuations may be attenuated even when the type of liquid 200 is changed. When the type of liquid 200 is changed, the ease of holding the air layer 206 in the groove portion 204 differs. By having the groove portion 204 with a different shape or volume, the groove forming portion 202 may be able to hold the air layer 206 even when the type of liquid 200 is changed. In this case, even if the type of liquid 200 is changed, the flow path member 212 can be used as it is without being changed, and an increase in costs can be suppressed.

[0165] Although different shapes of groove portion 204 do not strictly coincide with different volumes of groove portion 204, different shapes of groove portion 204 often result in different volumes of groove portion 204. Therefore, different shapes of groove portion 204 may be considered to be the same as different volumes of groove portion 204.

[0166] When the shape or volume of groove formation portion 202 is different, the contact angle with respect to liquid must be 90° or more in at least one of the directions in which the concave or convex portions are arranged. This allows groove formation portion 202 to exhibit liquid repellency even when the shape or volume of groove formation portion 202 is different, and allows air layer 206 (which may be gas layer 208, etc.) to be held in groove portion 204.

[0167] In the figure, an example of one direction is shown by dashed lines s7 and s8, and an example of the interval a1 of the groove portion 204 and the width b1 of the groove portion 204 in one direction (for example, the left-right direction of the paper) is shown. This embodiment is not limited to this example, and the one direction, the interval a1, and the width b1 can be selected as appropriate. The dashed line s9 in FIG. 17(B) is a direction along the one direction, but the cross section of the dashed line s9 does not satisfy the requirement that the contact angle is 90° or more. However, the cross section along the dashed line s8 satisfies the requirement that the contact angle is 90° or more, and therefore satisfies the requirements of the present invention. In this way, it is sufficient that the requirement that the contact angle is 90° or more is satisfied in at least one cross section along the one direction.

[0168] 17(A) and (B) are schematic plan views, but may be curved surfaces. Therefore, the examples shown in Fig. 17(A) and (B) are also applicable to cylindrical liquid flow paths 210 as shown in Fig. 7A and Fig. 7B, and other cylindrical flow path members 212.

[0169] 18(A) and (B) are schematic cross-sectional views for explaining another example of this embodiment. The example shown in (A) is an example in which the cross-sectional shape of the groove portion 204 is rectangular. As shown in the figure, the depth (which may also be referred to as height) of the groove portion 204 may be different from one another. When the depth of the groove portion 204 is different, the volume of the air layer 206 held by the groove portion 204 is different. Therefore, there is a difference in the compliance of the air layer 206, and as in the above, pressure fluctuations can be further attenuated by compliance having a plurality of resonant frequencies (resonant frequency bands), and pressure fluctuations can be attenuated more efficiently.

[0170] The example shown in (B) includes a case where the cross-sectional shape of the groove portion 204 is a shape other than a rectangle. As shown in the figure, the cross-sectional shape of the groove portion 204 may be a shape having a curved surface, a triangular shape, or the like. Even in the example shown in (B), the cross-sectional shapes of the groove portion 204 are different, and therefore the volume of the air layer 206 held by the groove portion 204 is different. For this reason, there is a difference in the compliance of the air layer 206, and as in the above, pressure fluctuations can be further attenuated by compliance having a plurality of resonant frequencies (resonant frequency bands), and pressure fluctuations can be attenuated more efficiently.

[0171] Seventh embodiment Next, another embodiment of the present invention will be described. In the present invention, the interval and width of the grooves 204 in one direction may be the same value or may be different values. In this embodiment, the interval and width of the grooves 204 in one direction have two or more values. The interval and width of the grooves 204 having two or more values ​​in one direction may be referred to as the interval and width of the grooves 204 being modulated, for example.

[0172] By having two or more values ​​for the spacing and width of the groove portion 204 in one direction, a difference occurs in the compliance of the air layer 206 held in the groove formation portion 202. Therefore, the pressure fluctuation in the liquid flow path 210 can be attenuated by the compliance having a plurality of resonant frequencies (resonant frequency bands). Therefore, in this embodiment, the frequency band of pressure fluctuations that can be attenuated can be widened, and pressure fluctuations can be attenuated more efficiently.

[0173] 19 is a schematic plan view for explaining an example of this embodiment. (A) is a schematic plan view of this example, (B) is a schematic xx cross-sectional view of (A), and (C) is a schematic yy cross-sectional view of (A). In the plane shown in (A), the xx direction (left-right direction on the paper) is direction 1, and the yy direction (up-down direction on the paper) is direction 2.

[0174] In this example, the groove formation portion 202 satisfies the requirement that the contact angle θ with respect to the liquid is 90° or more in a cross section in the arrangement direction of the recesses or protrusions. In this example, the contact angle θ with respect to the liquid is 90° or more in cross sections in directions 1 and 2.

[0175] In this example, most of the planar shapes of the grooves 204 are triangular, but the grooves 204m have a planar shape that resembles three combined rectangles. By forming the grooves 204m, the intervals and widths of the grooves 204 have two or more values.

[0176] As shown in (B), the interval between grooves 204 in direction 1 has two values, a1 and ax. In addition, the width between grooves 204 in direction 1 has two values, b1 and bx. The interval ax and the width bx correspond to groove 204m. Air layer 206 held in groove 204m has a compliance different from that of the other grooves 204, and therefore pressure fluctuations can be further attenuated by compliance with multiple resonant frequencies (resonant frequency bands).

[0177] As shown in (C), in this example, the spacing between grooves 204 in direction 2 also has two values, a1' and ay. The width of grooves 204 in direction 2 has two values, b1' and by. The spacing ay and width by correspond to groove 204m. Air layer 206 held in groove 204m has a different compliance from the other grooves 204, so pressure fluctuations can be further attenuated by compliance with multiple resonant frequencies (resonant frequency bands).

[0178] The value of the width of the groove portion 204 in one direction can be appropriately selected. When the minimum width of the groove portion 204 in one direction is bm and the maximum width of the groove portion 204 in the one direction is bM, the ratio of bm to bM is preferably 1:1 to 1:10. In this case, one or more of the following effects (1) to (4) can be obtained. When the ratio of bm to bM is 1:1, the width of the groove portion 204 has one value.

[0179] (1) By forming air layers (grooves) with different compliance, the resonant frequency of the air layer can be expanded, which resonates with pressure fluctuations to obtain a higher damping effect. (2) As shown in the Cassie-Baxter equation, by modulating the width of the grooves, it is possible to give each groove a different contact angle. By modulating the width of the grooves to give them different contact angles, it is possible to preserve some of the air layer from collapsing due to sudden pressure fluctuations. This prevents the air layer from being completely destroyed. (3) As shown in the Cassie-Baxter equation, by modulating the width of the grooves, it is possible to give each groove a different contact angle. By modulating the width of the grooves to give them different contact angles, the grooves can hold an air layer for liquids with different surface energies. This expands the compatibility with ink types and ink temperatures. (4) By keeping the ratio within 10 times, a single processing method can be applied, making manufacturing easier.

[0180] The interval of the grooves 204 in one direction may be one value or may be different values. The interval of the grooves 204 is adjusted, for example, so that cosθ required for obtaining water repellency is obtained for the contact angle cosθb of the grooves (air layer) to be installed. The interval of the grooves 204 may be set such that, for example, the minimum width of the interval of the grooves 204 in one direction is am and the maximum width of the grooves 204 in the one direction is aM, the ratio of am to aM is 1:1 to 1:10. When the interval of the grooves 204 is in this range, it is expected that wear due to friction and damage during assembly can be suppressed, and mechanical durability is improved. Note that when the ratio of am to aM is 1:1, the interval of the grooves 204 is one value.

[0181] It is preferable to satisfy the above formula (13) even when the interval and width of the groove portion 204 have two or more values ​​as in this example. In this case, even when the interval and width of the groove portion 204 have two or more values, the groove formation portion 202 is more likely to exhibit liquid repellency. In this example, the above formula (13) is satisfied in both directions 1 and 2.

[0182] Next, a supplementary effect when the interval and width of groove portion 204 have two or more values ​​will be described with reference to Fig. 20. Fig. 20(A) to (C) are schematic cross-sectional views of a main part of groove formation portion 202 in one direction, and (A) to (C) show different liquids. (A) is liquid 200, (B) is liquid 200', and (C) is liquid 200''.

[0183] In the grooved portion 202 of this example, the spacing between the grooves 204 has two values, a1 and a2. The spacing a2 is twice as large as a1. In the grooved portion 202 of this example, the width between the grooves 204 has two values, b1 and b2. The width b2 is twice as large as b1. The spacing a2 and the width b2 correspond to the groove 204n.

[0184] As shown in the figure, different types of liquid affect whether groove portion 204 can hold air layer 206. As shown diagrammatically in the figure, different types of liquid affect whether groove portions 204, 204n can hold air layer 206 for liquids 200, 200', 200''. Whether a groove portion can hold air layer 206 is affected not only by the width of the groove portion but also by the distance between adjacent groove portions. Therefore, as shown in (A) and (C) for example, even if width b1 is the same, there will be groove portions 204 that hold air layer 206 and groove portions 204 that cannot hold air layer 206.

[0185] By having two or more values ​​for the interval and width of the groove portion 204, the air layer 206 may be retained even if the type of the liquid 200 is changed. In this case, even if the type of the liquid 200 is changed, the flow path member 212 can be used as it is without modification, and an increase in costs can be suppressed.

[0186] <Eighth embodiment> Next, another embodiment of the present invention will be described. In the above embodiment, a case has been described in which a groove forming portion 202 having a plurality of groove portions 204 formed by recesses or protrusions is used. The effects of the present invention are not limited to the groove forming portion 202 having groove portions 204, but can also be obtained in the case in which a partition having a through hole is used in the liquid flow path. In other words, in this embodiment as well, it is possible to provide a liquid ejection head that can reduce pressure fluctuations in the liquid flow path and is easy to manufacture. The present embodiment will be described below, and the description of the same matters as those in the above embodiment will be omitted.

[0187] The liquid ejection head of this embodiment comprises a nozzle for ejecting liquid, a liquid flow path connected to the nozzle, and a pressure generating means for varying the pressure of the liquid in the liquid flow path, wherein the liquid flow path has a portion separated by a partition, the pressure of the liquid in the two flow paths separated by the partition is the same in positive and negative relative to atmospheric pressure, at least a portion of the partition is provided with a through hole forming portion having a plurality of through holes penetrating the partition, and the through hole forming portion has a contact angle with the liquid of 90° or more, at least in a cross section in the arrangement direction of the through holes.

[0188] The example described in the above embodiment is an example in which the groove forming portion 202 for holding the air layer 206 and the like is provided on the liquid flow path 210 side of the flow path member 212, in other words, on the inside of the wall forming the liquid flow path 210. On the other hand, in this embodiment, a partition wall separating the liquid flow paths 210 is inserted into the liquid flow path 210, and the partition wall holds the air layer 206 and has a damping function. In this embodiment, it is sufficient to insert a partition wall capable of holding the air layer 206 into the liquid flow path 210, which makes it easy to manufacture and increases the degree of freedom in installation. In addition, because the degree of freedom in installation is good, the effect of attenuating pressure fluctuations in the liquid flow path 210 can also be improved.

[0189] 21 is a diagram for explaining one example of this embodiment. (A) is a diagram for explaining a cylindrical liquid flow path 210 or a flow path member 212, and is an example in which no partition is provided. (B) is an example in which a partition 240 that divides the liquid flow path 210 into two is provided in addition to (A). (C) is a schematic cross-sectional view of (B).

[0190] As shown in (C), the partition 240 is provided with a through-hole forming portion 244 having a plurality of through-holes 242 penetrating the partition 240. An air layer 206 (which may be a gas layer 208, etc.) is held in the through-hole 242. In (B) and (C), two flow paths separated by the partition 240 are illustrated as liquid flow paths 210a and 210b, respectively.

[0191] The through hole forming portion 244 has a contact angle of 90° or more with respect to the liquid 200 at least in a cross section in the arrangement direction of the through holes 242. When the contact angle is 90° or more, it can be said that the through hole forming portion 244 has liquid repellency with respect to the liquid 200. The contact angle of 90° or more with respect to the liquid 200 of the through hole forming portion 244 needs to be satisfied on both sides of the through hole forming portion 244. The through hole forming portion 244 of this example satisfies the requirement that the contact angle is 90° or more on the liquid flow path 210a side and the liquid flow path 210b side.

[0192] 22 is a diagram for illustrating, in a schematic manner, that the contact angle θ of the through-hole forming portion 244 with respect to the liquid 200 is 90° or more, and is a diagram similar to FIG. 1. As shown in the figure, it is possible to prevent the liquid 200 from entering the through-hole 242.

[0193] The contact angle θ may be obtained by measuring the through hole forming portion 244 in which the through hole 242 is formed. The contact angle θ can be measured, for example, as shown in FIG. 6(A) above. Alternatively, θa and θb may be obtained as shown in FIGS. 6(A) and 6(B) above, and the contact angle θ may be obtained using the above formula (1). When the above formula (1) is applied to this embodiment, the average value a of the interval between adjacent groove portions 204 in one direction is replaced with the average value c of the interval between adjacent through holes 242 in one direction. In addition, the average value b of the width of the groove portions 204 in one direction is replaced with the average value d of the width of the through holes 242 in one direction (formula (18) described later).

[0194] The pressure of the liquid 200 in the two flow paths separated by the partition wall 240 has the same positive and negative pressure with respect to the atmospheric pressure. An example will be described in which the pressure of the liquid 200 has the same positive and negative pressure with respect to the atmospheric pressure. For example, when the atmospheric pressure is 1 atm, the two liquid flow paths 210a, 210b include the following cases. (Example 1) When the pressure of the liquid 200 in the liquid flow path 210a is 0.99 atm (−0.01 atm relative to atmospheric pressure) and the pressure of the liquid 200 in the liquid flow path 210b is 0.98 atm (−0.02 atm relative to atmospheric pressure) (Example 2) When the pressure of the liquid 200 in the liquid flow path 210a is 1.01 atm (atmospheric pressure +0.01 atm) and the pressure of the liquid 200 in the liquid flow path 210b is 1.02 atm (atmospheric pressure +0.02 atm) The atmospheric pressure is not limited to 1 atmosphere, but can be appropriately selected according to the atmospheric pressure when the head is used.

[0195] In this embodiment, the contact angle of the through hole forming portion 244 with respect to the liquid 200 is 90° or more, and the pressure of the liquid 200 in the liquid flow paths 210a, 210b is the same as the positive and negative pressures with respect to the atmospheric pressure. This makes it possible to prevent the liquid flow paths 210a, 210b from being short-circuited (connected) through the through hole 242, and the air layer 206 is maintained in the through hole 242. If the configuration of this embodiment is not satisfied, not only may the liquid flow paths 210a, 210b be short-circuited (connected) through the through hole 242, but the through hole forming portion 244 may be damaged due to the pressure difference.

[0196] As a method for making the pressure of the liquid 200 in the liquid flow paths 210a, 210b equal in positive and negative with respect to atmospheric pressure, for example, the flow paths on both sides of the partition 240 are connected to each other on the upstream and downstream sides of the partition 240 in the liquid flow path 210. For example, by partially arranging a partition in the flow path and connecting the partially separated flow paths on the upstream and downstream sides of the partition 240, it is possible to make the pressures of the flow paths branched by the partition approximately equal.

[0197] 23(A) and (B) are schematic cross-sectional views for explaining the air layer 206 held in the through-hole 242, and are similar to Fig. 21(C). In (A), the flow direction of the liquid 200 in the liquid flow channel 210a and the flow direction of the liquid 200 in the liquid flow channel 210b are shown by white arrows. The liquid 200 flows in the same direction in the liquid flow channel 210a and the liquid flow channel 210b.

[0198] In (A), the pressure from the liquid 200 in the liquid flow paths 210a and 210b is shown diagrammatically by black arrows. By satisfying the configuration of this embodiment described above (the configuration of the contact angle and the configuration of the positive and negative pressure), the air layer 206 is held in the through-hole 242 even when pressure from the liquid 200 is applied.

[0199] 1B is a schematic diagram illustrating the effect of the present embodiment due to the air layer 206. In the through-hole forming portion 244 of the present embodiment, the pressure fluctuation in the liquid flow path 210 can be attenuated, similar to the groove forming portion 202 of the above embodiment.

[0200] (B) As schematically shown by the double arrows, in the air layer 206 of the through-hole 242, the position of the interface of the liquid 200 varies as shown by the broken line in the figure. Such variation is the same as the variation in FIG. 2(C), but in this embodiment, the position of the interface on the liquid flow path 210a side and / or the position of the interface on the liquid flow path 210b side varies. Thereby, both the pressure variation of the liquid 200 in the liquid flow path 210a and the pressure variation of the liquid 200 in the liquid flow path 210b can be attenuated.

[0201] The air layer 206 of the through-hole 242 attenuates the pressure variation, for example, due to the compliance of the air layer 206. The compliance of the air layer 206 of the through-hole 242 can be considered in the same manner as the compliance of the air layer 206 of the groove portion 204 described in the above embodiment.

[0202] As described above, the matters described in the above embodiment are also applicable in this embodiment. For example, it is preferable to satisfy the aspect ratio relational expression (the above formula (13)) described in the above embodiment in this embodiment. The aspect ratio relational expression in this embodiment is shown below.

[0203] When the average value of the intervals between adjacent through-holes 242 in one direction is c and the average value of the widths of the through-holes 242 in the one direction is d, c and d are 0 < d / c ≦ 2 Formula (17) It is preferable to satisfy this. In this case, the through-hole forming portion 244 is likely to exhibit the lotus effect (liquid repellency), and it is easy to make the contact angle θ of the liquid with respect to the through-hole forming portion 244 90° or more.

[0204] The above formula (17) will be described with reference to FIG. 24. The intervals between the through holes 242 in one direction are c1, c2,..., and the widths of the through holes 242 in the one direction are d1, d2, d3,.... The one direction is any direction, and an example of this is the arrangement direction of the through holes 242. In this embodiment, the intervals between the through holes 242 may be the same for each through hole 242, or may be different. In this embodiment, the widths of the through holes 242 may be the same for each groove portion 204, or may be different.

[0205] The average value of the intervals between adjacent through holes 242 in one direction is c, and the average value of the widths of the through holes 242 in the one direction is d. The number of intervals and widths of the through holes 242 when calculating the average value is preferably large, but may be selected appropriately.

[0206] In this embodiment, the same formula for the contact angle (the above formula (1)) as in the above embodiment can be defined. The formula for the contact angle in this embodiment can be expressed as follows. cosθ=c×cosθc+d×cosθd Equation (18) In the above formula (18), θ is the contact angle θ of the through-hole forming portion 244 with respect to the liquid 200, θc is the contact angle between the partition wall 240 (material A in FIG. 22) and the liquid 200, and θd is the contact angle between the air layer 206 (material B in FIG. 22) and the liquid 200. The contact angles θc and θd can be obtained as shown in the above-mentioned FIGS. 6(A) and (B).

[0207] In order to determine whether the through-hole formation portion 244 exhibits liquid repellency, the contact angle θ may be measured using the liquid 200 on the through-hole formation portion 244, as in the case of the groove formation portion 202, or cos θ may be calculated using the above formula (18).

[0208] In this embodiment, the through holes 242 may also be arranged in the other direction. For example, as in the examples shown in Figs. 15 to 17, the through holes 242 may be arranged in the other direction. Furthermore, the planar shape of the through holes 242 (the shape of the through holes 242 as viewed from the liquid flow paths 210a, 210b side) may be appropriately selected, and may be a circle, a polygon, or the like. Furthermore, the shapes of the through holes 242 may be the same or different from each other.

[0209] Also in this embodiment, it is preferable that the interval and width of the through-holes 242 in one direction have two or more values. For example, in FIG. 24, c1 and c2 are not the same, and d1 to d3 are not the same. When the interval and width of the through-holes 242 have two or more values, the volume of the air layer 206 held by the through-holes 242 differs. Therefore, a difference occurs in the compliance of the air layer 206, and pressure fluctuations can be further attenuated by compliance with a plurality of resonant frequencies (resonant frequency bands), and pressure fluctuations can be attenuated more efficiently.

[0210] Also in this embodiment, when the minimum width of the through hole 242 in one direction is dm and the maximum width of the through hole 242 in the one direction is dM, the ratio of dm to dM is preferably 1:1 to 1:10. In this case, a difference occurs in the compliance of the air layer 206. This makes it possible to attenuate pressure vibrations with different vibration periods of the short period vibration Tc and the refill vibration, and since the ratio of the maximum dimension to the minimum dimension is 10 times or less, the same processing method can be applied.

[0211] In addition, when the minimum width of the interval between the through holes 242 in one direction is cm, and the maximum width of the groove portion 204 in the one direction is cM, the ratio of cm to cM is preferably 1:1 to 1:10. In this case, a difference occurs in the compliance of the air layer 206. This makes it possible to attenuate pressure vibrations with different vibration periods, the short period vibration Tc and the refill vibration, and since the ratio of the maximum dimension to the minimum dimension is 10 times or less, the same processing method can be applied.

[0212] <Ninth embodiment> Next, other configurations of the liquid ejection head of the present invention and embodiments of the liquid ejection apparatus will be described.

[0213] The liquid ejection device of the present invention includes a head module equipped with a liquid ejection head of the present invention. The liquid ejection head and head module according to this embodiment will be described with reference to Fig. 25 to Fig. 28. Fig. 25 is a cross-sectional explanatory view taken along the short side of the head of a head module according to one embodiment, Fig. 26 is an exploded perspective explanatory view of the head module, Fig. 27 is an exploded perspective explanatory view of the head module as viewed from the nozzle surface side, and Fig. 28 is an exploded perspective explanatory view showing the head, base member, and cover member of the head module.

[0214] The head module 100 includes a plurality of heads 101 which are liquid ejection heads that eject liquid, a base member 102, a cover member 103, a heat dissipation member 104, a manifold 105, a printed circuit board (PCB) 106, and a module case 107.

[0215] The head 101 includes a nozzle substrate 10, a flow path substrate 20, a vibration plate 30, a holding substrate 50, and a frame member 70. The head 101 is an example of the liquid ejection head of this embodiment.

[0216] The nozzle substrate 10 has nozzles 11 formed therein. The flow path substrate 20 has pressure chambers 21 and the like formed therein, which communicate with the nozzles 11. The pressure chambers 21 may also be referred to as individual liquid chambers or the like. The vibration plate 30 forms a part of the pressure chambers 21, and vibrates due to the piezoelectric elements 40. The holding substrate 50 is laminated on the vibration plate 30. The frame member 70 is laminated on the holding substrate 50. The frame member 70 may also be referred to as a common flow path member or the like.

[0217] The flow path substrate 20, together with the pressure chamber 21, forms a supply-side individual flow path 22 communicating with the pressure chamber 21, and a recovery-side individual flow path 24 communicating with the pressure chamber 21. The flow path substrate 20 may be referred to as an individual flow path plate or the like.

[0218] The holding substrate 50 forms a supply-side intermediate individual flow path 51 that communicates with the supply-side individual flow path 22 via the opening 31 of the vibration plate 30, and a recovery-side intermediate individual flow path 52 that communicates with the recovery-side individual flow path 24 via the opening 32 of the vibration plate 30. The holding substrate 50 may be referred to as an intermediate flow path plate or the like.

[0219] The holding substrate 50 may be composed of a plurality of substrates, and in this embodiment, the holding substrate 50 is composed of a first holding substrate and a second holding substrate. As described later, the liquid chamber substrate in this embodiment includes a flow path substrate 20 and a first holding substrate which is a part of the holding substrate 50. The liquid chamber substrate in this embodiment is bonded to the nozzle substrate 10, and is also bonded to the second holding substrate which is a part of the holding substrate 50.

[0220] The frame member 70 forms a supply side common flow path 71 that communicates with the supply side intermediate individual flow path 51, and a recovery side common flow path 72 that communicates with the recovery side intermediate individual flow path 52. The supply side common flow path 71 communicates with the supply port 81 via a flow path 151 of the manifold 105. The recovery side common flow path 72 communicates with the recovery port 82 via a flow path 152 of the manifold 105. The frame member 70 may be referred to as a common flow path member.

[0221] The printed circuit board 106 and the piezoelectric element 40 of the head 101 are connected via a flexible wiring member 90, on which a driver IC 91 (drive circuit) is mounted.

[0222] In this embodiment, multiple heads 101 are attached to a base member 102 at intervals. The heads 101 are attached to the base member 102 by inserting the heads 101 into openings 121 provided in the base member 102, and then bonding and fixing the peripheral edge of the nozzle substrate 10 of the heads 101 to a cover member 103 bonded and fixed to the base member 102. In addition, a flange portion 70a provided on the outside of a frame member 70 of the heads 101 is bonded and fixed to the base member 102.

[0223] The fixing structure for the head 101 and the base member 102 is not limited, and may be achieved by adhesion, caulking, screw fixing, or the like.

[0224] Here, the base member 102 is preferably formed from a material with a low linear expansion coefficient. Examples include 42alloy, which is iron with nickel added, and Invar material. Invar material is used in this embodiment. As a result, even if the head 101 generates heat and the temperature of the base member 102 rises, the amount of expansion of the base member 102 is small, so that the nozzle is less likely to deviate from the predetermined nozzle position, and deviation of the landing position can be suppressed.

[0225] The nozzle substrate 10, the flow path substrate 20, and the vibration plate 30 are formed from a silicon single crystal substrate, and the linear expansion coefficient of the base member 102 is set to be approximately the same. This makes it possible to reduce nozzle position deviation due to thermal expansion.

[0226] FIG. 29 is an exploded perspective view for illustrating a schematic configuration of a substrate of the liquid ejection head in this embodiment.

[0227] The liquid chamber substrate 122 is bonded to the nozzle substrate 10. The liquid chamber substrate 122 is also bonded to a damper frame 125 (second holding substrate). A damper 123 is provided at least partially between the liquid chamber substrate 122 and the damper frame 125. The damper 123 reduces impact, for example, by dissipating the energy of the piezoelectric element 40. The method for bonding the substrates is not particularly limited and can be selected appropriately, and examples include a method using an adhesive.

[0228] In this embodiment, the holding substrate 50 is composed of a first holding substrate and a second holding substrate, and the damper frame 125 is an example of the second holding substrate. A subframe 121 described below is an example of the first holding substrate. In this embodiment, the liquid chamber substrate 122 includes the subframe 121, that is, the liquid chamber substrate 122 includes a part of the holding substrate 50 (first holding substrate) (see FIG. 30). Therefore, in FIG. 25, the part including the part of the holding substrate 50 (first holding substrate) and the flow path substrate 20 becomes the liquid chamber substrate 122.

[0229] As described above, the nozzles 11 that eject liquid are formed on the nozzle substrate 10. The liquid chamber substrate 122 has pressure chambers 21 formed therein that correspond to the nozzles, and is provided with piezoelectric elements 40 (pressure generating means) that apply pressure to the pressure chambers. The piezoelectric elements 40 convert electrical energy into mechanical energy such as displacement and force, and contribute to the ejection of liquid.

[0230] FIG. 30 is an explanatory diagram in which a main part of the head 101 is enlarged in the cross-sectional explanatory diagram of FIG. The head 101 of this example has a liquid chamber substrate 122, a nozzle substrate 10, and a damper frame 125. The liquid chamber substrate 122 has pressure chambers 21 whose volume changes due to piezoelectric elements 40 (pressure generating means). The nozzle substrate 10 has nozzles 11 corresponding to the pressure chambers 21, and is bonded to the liquid chamber substrate 122. The damper frame 125 is bonded to the liquid chamber substrate 122 on the side opposite to the side to which the nozzle substrate 10 is bonded.

[0231] The liquid chamber substrate 122 in this embodiment may be composed of one substrate or multiple substrates. The liquid chamber substrate 122 in this example is composed of a flow path substrate 20 and a subframe 121. The subframe 121 is a part of the holding substrate 50, and is also referred to as a first holding substrate. The liquid chamber substrate 122 in this example has a piezoelectric element 40 as an example of a pressure generating means, and a vibration plate 30. The volume of the pressure chamber 21 changes when the vibration plate 30 is deformed by the piezoelectric element 40.

[0232] A change in the volume of the pressure chamber 21 causes droplets to be ejected from the nozzle 11. The nozzle 11 is a hole for ejecting liquid to the outside as droplets. An example of the liquid is ink, and droplets of ink are also called ink droplets.

[0233] The subframe 121 has a gap 124 on the flow path substrate 20 side for securing a drive region for the piezoelectric element 40. The subframe 121 is also joined to a damper 123, and has a first damper chamber 126. The first damper chamber 126 is provided for securing a space in which the damper 123 can vibrate.

[0234] In this example, a damper 123 is provided at least partially between the damper frame 125 and the liquid chamber substrate 122. By providing the damper 123, it is possible to disperse the energy generated when the piezoelectric element 40 deforms, thereby reducing the impact.

[0235] The damper frame 125 may be referred to as a frame substrate. The nozzle substrate 10, the liquid chamber substrate 122, and the damper frame 125 may be collectively referred to as a module substrate.

[0236] The damper frame 125 in this example has a second damper chamber 127 on the subframe 121 side. The second damper chamber 127 is provided to ensure a space in which the damper 123 can vibrate.

[0237] The material of the substrate can be appropriately selected, and it is particularly preferable that the nozzle substrate 10, the liquid chamber substrate 122, and the damper frame 125 are made of Si, which facilitates processing to reduce the thickness and size.

[0238] In this embodiment, another example is shown below. 31 is a diagram for explaining another example, and is another schematic plan view in the stacking direction of the substrates. As shown in the figure, the damper frame 125 (frame substrate) is larger than the other substrates only in the longitudinal direction. In the lateral direction, the damper frame 125 is the same size as the liquid chamber substrate 122 and the nozzle substrate 10.

[0239] That is, in this example, in a plane viewed from the stacking direction of the substrates, the nozzle substrate, the liquid chamber substrate and the frame substrate have a longitudinal direction and a transverse direction, the longitudinal directions of these substrates are the same direction, the transverse directions of these substrates are the same direction, the liquid chamber substrate has an outer shape that is larger than the nozzle substrate only in the longitudinal direction, and the frame substrate has an outer shape that is larger than the liquid chamber substrate only in the longitudinal direction. In this example, on a plane viewed from the stacking direction of the substrates, the size relationship of the substrates only in the longitudinal direction is nozzle substrate 10<liquid chamber substrate 122<damper frame 125.

[0240] In this example as well, the risk of the liquid chamber substrate 122 and the nozzle substrate 10 coming into contact with the outside and being damaged can be reduced. Meanwhile, in this example, since the damper frame 125 is larger than the other substrates only in the longitudinal direction, the expansion of the damper frame 125 can be minimized compared to the conventional case. This makes it possible to suppress an increase in the cost of parts. In this embodiment, if there is a position where there is a high risk of the substrate coming into contact depending on the jig or device used in the manufacturing process, it is possible to appropriately design the damper frame 125 so that the size is expanded only in that portion.

[0241] 32 is a diagram for explaining another example different from the above, and is another schematic plan view in the stacking direction of the substrates. As shown in the figure, the damper frame 125 (frame substrate) is larger than the other substrates only in the short side direction. In the long side direction, the damper frame 125 is the same size as the liquid chamber substrate 122 and the nozzle substrate 10.

[0242] That is, in this example, in a plane viewed from the stacking direction of the substrates, the nozzle substrate, the liquid chamber substrate and the frame substrate have a longitudinal direction and a lateral direction, the longitudinal directions of these substrates are the same direction, the lateral directions of these substrates are the same direction, the liquid chamber substrate has an outer shape that is larger than the nozzle substrate only in the lateral direction, and the frame substrate has an outer shape that is larger than the liquid chamber substrate only in the lateral direction. In this example, on a plane viewed from the stacking direction of the substrates, the size relationship of the substrates in only the short side direction is nozzle substrate 10<liquid chamber substrate 122<damper frame 125.

[0243] In this example as well, the risk of the liquid chamber substrate 122 and the nozzle substrate 10 coming into contact with the outside and being damaged can be reduced. Meanwhile, in this example, since the damper frame 125 is larger than the other substrates only in the short side direction, the expansion of the damper frame 125 can be minimized compared to the conventional art. This makes it possible to suppress an increase in the cost of parts. In this embodiment, if there is a position where there is a high risk of the substrate coming into contact depending on the jig or device used in the manufacturing process, it is possible to appropriately design the damper frame 125 so that the size is expanded only in that portion.

[0244] For example, aspects of the present invention are as follows. <1> A nozzle for discharging a liquid; a flow path member having a liquid flow path communicating with the nozzle; a pressure generating means for varying the pressure of the liquid in the liquid flow path, a groove forming section is provided in at least a part of the flow path member, the groove forming section having a plurality of grooves formed by at least one of a plurality of recesses or a plurality of protrusions on the liquid flow path side, the plurality of grooves being formed by the recesses or the protrusions; The groove forming portion has a contact angle with respect to the liquid of 90° or more at least in a cross section in the arrangement direction of the recesses or the protrusions. A liquid ejection head comprising: <2> When the average value of the interval between adjacent groove portions in one direction is a and the average value of the width of the groove portions in the one direction is b, a and b are 0 Fulfill Characterized by <1> The liquid ejection head according to claim 1. <3> The interval and width of the grooves in one direction have two or more values. Characterized by <1> or <2> The liquid ejection head according to claim 1. <4> When the minimum width of the groove portion in the one direction is bm and the maximum width of the groove portion in the one direction is bM, the ratio of bm to bM is 1:1 to 1:10. Characterized by <1> or <2> The liquid ejection head according to claim 1. <5> The nozzle and the pressure generating means are provided in plurality, the liquid flow path includes a plurality of individual liquid chambers each in communication with the plurality of nozzles, and a common liquid chamber in communication with the plurality of individual liquid chambers; the common liquid chamber communicates with the individual liquid chambers via fluid resistance portions provided for the individual liquid chambers, The liquid flows in the common liquid chamber and then in the individual liquid chambers. The pressure generating means varies the pressure of the liquid in the individual liquid chamber, The groove forming portion is provided in the liquid flow path upstream of the fluid resistance portion. Characterized by <1> from <4> 2. The liquid ejection head according to claim 1 . <6> The nozzle and the pressure generating means are provided in plurality, the liquid flow path includes individual liquid chambers each in communication with the plurality of nozzles, a supply-side common liquid chamber in communication with the plurality of individual liquid chambers, and a recovery-side common liquid chamber in communication with the plurality of individual liquid chambers; the supply-side common liquid chamber communicates with the individual liquid chambers via a supply-side fluid resistance portion provided for each of the individual liquid chambers; the recovery side common liquid chamber communicates with the individual liquid chambers via recovery side fluid resistance portions provided for the individual liquid chambers,​ the liquid flows through the supply-side common liquid chamber, the individual liquid chambers, and the recovery-side common liquid chamber in this order; The pressure generating means varies the pressure of the liquid in the individual liquid chamber, The groove forming portion is provided in at least one of the liquid flow path upstream of the supply side fluid resistance portion and the liquid flow path downstream of the recovery side fluid resistance portion. Characterized by <1> from <4> 2. The liquid ejection head according to claim 1 . <7> The groove formation portion includes a liquid-repellent layer that is liquid-repellent to the liquid. Characterized by <1> from <6> 2. The liquid ejection head according to claim 1 . <8> The recesses or protrusions are arranged in two directions. Characterized by <1> from <7> 2. The liquid ejection head according to claim 1 . <9> A nozzle for discharging a liquid; A liquid flow path communicating with the nozzle; a pressure generating means for varying the pressure of the liquid in the liquid flow path, The liquid flow path has a portion separated by a partition wall, the pressure of the liquid in the two flow paths separated by the partition is equal in positive and negative with respect to atmospheric pressure, a through-hole forming portion having a plurality of through-holes penetrating the partition wall is provided in at least a portion of the partition wall, The through-hole formation portion has a contact angle with respect to the liquid of 90° or more at least in a cross section in the arrangement direction of the through-holes. A liquid ejection head comprising: <10> When the average value of the interval between adjacent through holes in one direction is c and the average value of the width of the through holes in the one direction is d, c and d are 0 <d / c≦2 Fulfill Characterized by <9> The liquid ejection head according to claim 1. <11> The interval and width of the through holes in one direction have two or more values. Characterized by <9> or <10> The liquid ejection head according to claim 1. <12> When the minimum width of the through hole in the one direction is dm and the maximum width of the through hole in the one direction is dM, the ratio of dm to dM is 1:1 to 1:10. Characterized by <9> from <10> 2. The liquid ejection head according to claim 1 . <13> <1> from <12> The liquid ejection head according to any one of claims 1 to 4 is provided. A liquid ejection device comprising: [Explanation of symbols]

[0245] 11 Nozzle 200 liquid 202 Groove forming part 204 Groove 206 Air Layer 208 Gas Layer 210, 210a, 210b Liquid flow path 212 Flow path components 214 Contact part 216 Syringe 218 Liquid repellent film 220 Pressure generating means 222 Individual liquid chamber 224 Common Liquid Chamber 226 Fluid resistance section 230 Supply side common liquid chamber 232 Recovery side common liquid chamber 234 Supply side fluid resistance section 236 Recovery side fluid resistance part 240 Bulkhead 242 Through hole 244 Hole forming part [Prior art documents] [Patent documents]

[0246] [Patent Document 1] Patent Publication No. 2021-154748

Claims

1. A nozzle for discharging a liquid; a flow path member having a liquid flow path communicating with the nozzle; a pressure generating means for varying the pressure of the liquid in the liquid flow path, a groove forming section is provided in at least a part of the flow path member, the groove forming section having a plurality of grooves formed by at least one of a plurality of recesses or a plurality of protrusions on the liquid flow path side, the plurality of grooves being formed by the recesses or the protrusions; The groove forming portion has a contact angle with respect to the liquid of 90° or more at least in a cross section in the arrangement direction of the recesses or the protrusions. A liquid ejection head comprising:

2. When the average value of the interval between adjacent groove portions in one direction is a and the average value of the width of the groove portions in the one direction is b, a and b are 0<b / a≦2 Fulfill 2. The liquid ejection head according to claim 1.

3. The interval and width of the grooves in one direction have two or more values.

2. The liquid ejection head according to claim 1.

4. When the minimum width of the groove portion in the one direction is bm and the maximum width of the groove portion in the one direction is bM, the ratio of bm to bM is 1:1 to 1:

10.

2. The liquid ejection head according to claim 1.

5. The nozzle and the pressure generating means are provided in plurality, the liquid flow path includes a plurality of individual liquid chambers each in communication with the plurality of nozzles, and a common liquid chamber in communication with the plurality of individual liquid chambers; the common liquid chamber communicates with the individual liquid chambers via fluid resistance portions provided for the individual liquid chambers, The liquid flows in the common liquid chamber and then in the individual liquid chambers. The pressure generating means varies the pressure of the liquid in the individual liquid chamber, The groove forming portion is provided in the liquid flow path upstream of the fluid resistance portion.

2. The liquid ejection head according to claim 1.

6. The nozzle and the pressure generating means are provided in plurality, the liquid flow path includes individual liquid chambers each in communication with the plurality of nozzles, a supply-side common liquid chamber in communication with the plurality of individual liquid chambers, and a recovery-side common liquid chamber in communication with the plurality of individual liquid chambers; the supply-side common liquid chamber communicates with the individual liquid chambers via a supply-side fluid resistance portion provided for each of the individual liquid chambers; the recovery side common liquid chamber communicates with the individual liquid chambers via recovery side fluid resistance portions provided for the individual liquid chambers, the liquid flows through the supply-side common liquid chamber, the individual liquid chambers, and the recovery-side common liquid chamber in this order; The pressure generating means varies the pressure of the liquid in the individual liquid chamber, The groove forming portion is provided in at least one of the liquid flow path upstream of the supply side fluid resistance portion and the liquid flow path downstream of the recovery side fluid resistance portion.

2. The liquid ejection head according to claim 1.

7. The groove formation portion includes a liquid-repellent layer that is liquid-repellent to the liquid.

2. The liquid ejection head according to claim 1.

8. The recesses or protrusions are arranged in two directions.

2. The liquid ejection head according to claim 1.

9. A nozzle for discharging a liquid; A liquid flow path communicating with the nozzle; a pressure generating means for varying the pressure of the liquid in the liquid flow path, The liquid flow path has a portion separated by a partition wall, the pressure of the liquid in the two flow paths separated by the partition is equal in positive and negative with respect to atmospheric pressure, a through-hole forming portion having a plurality of through-holes penetrating the partition wall is provided in at least a portion of the partition wall, The through-hole forming portion has a contact angle with respect to the liquid of 90° or more at least in a cross section in the arrangement direction of the through-holes. A liquid ejection head comprising:

10. When the average value of the interval between adjacent through holes in one direction is c and the average value of the width of the through holes in the one direction is d, c and d are 0<d / c≦2 Fulfill 10. The liquid ejection head according to claim 9.

11. The interval and width of the through holes in one direction have two or more values.

10. The liquid ejection head according to claim 9.

12. When the minimum width of the through hole in the one direction is dm and the maximum width of the through hole in the one direction is dM, the ratio of dm to dM is 1:1 to 1:

10.

10. The liquid ejection head according to claim 9.

13. The liquid ejection head according to any one of claims 1 to 12 is provided. A liquid ejection device comprising:

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