JP7258386B1 - NOZZLE PLATE, LIQUID EJECTING DEVICE, AND LIQUID EJECTING METHOD - Google Patents

Abstract

A nozzle plate, a liquid ejecting apparatus, and a liquid ejecting method are provided in which air is less likely to be sucked from an ejection port. A nozzle plate (20) according to the present invention includes a storage chamber (21) in which a liquid is stored, a discharge channel (22c) communicating with the storage chamber (21), and an end portion of the discharge channel (22c) provided in a nozzle plate body (24). and an ejection port 22d for ejecting liquid. The nozzle plate 20 includes a liquid holding portion 60 that holds a liquid film M formed so as to cover the ejection port 22d and is surrounded by a restricting portion 61 that limits the spread of the liquid film M. S1/S2 is larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion 60 and S2 is the area of the ejection port 22d.

Description

The present invention relates to a nozzle plate, a liquid ejecting apparatus, and a liquid ejecting method.

2. Description of the Related Art Conventionally, liquid ejecting apparatuses for ejecting liquid have been used in the field of semiconductor manufacturing and the like. For example, the liquid ejecting apparatus described in Patent Document 1 includes a head main body, a pressurizing member attached to the head main body so as to be reciprocally movable and having a lower end projecting downward from the head main body, and a head main body. A nozzle plate provided on the lower surface and an actuator for vertically driving the pressure member are provided. The nozzle plate includes a concave portion that accommodates the lower end portion of the pressure member that protrudes from the head main body portion and forms a liquid storage chamber, an introduction channel for introducing the liquid into the concave portion, and an ejection port formed at the bottom of the concave portion. A flow path and a discharge port provided at the lower end of the discharge flow path are provided.

The introduction channel is connected to a liquid supply unit such as a syringe, and the liquid is supplied from the liquid supply unit to the storage chamber of the recess through the introduction channel. Next, the actuator is operated to move the pressing member downward. As a result, pressure is applied to the liquid, and the liquid is discharged from the discharge port at the lower end of the discharge channel. After the liquid is ejected, the pressure member is returned to its original position and waits until the next ejection. The liquid is discharged each time the pressurizing member reciprocates.

In addition, the liquid ejecting apparatus described in Patent Document 2 has a configuration similar to that of Patent Document 1, and includes a liquid holding portion that holds liquid around the ejection port, and the liquid to be ejected is supplied from the liquid supply portion. When doing so, the liquid is held in the liquid holding portion as a liquid mass. During the liquid ejection operation, this liquid mass and part of the liquid in the storage chamber are ejected as droplets. When changing the amount of liquid droplets to be ejected, the amount of the retained liquid mass is adjusted.

JP 2017-127837 A JP 2018-15741 A

In the liquid ejecting apparatus of Patent Document 1, after the liquid is ejected by moving the pressure member downward, the pressure member is lifted upward. At this time, air may be sucked from the ejection port and mixed into the storage chamber and the ejection channel. If air mixes with the liquid in the storage chamber or the discharge channel, the mixed air will be compressed and the discharge amount will change for each discharge, or the air in the discharge channel will bend the flow of the liquid, causing the liquid to flow into the discharge port. The ink may be ejected in an oblique direction without going straight down from the top. Furthermore, when there is a large amount of air in the ejection channel, the ejection amount may become extremely small, or ejection may not occur.

In the liquid ejecting apparatus of Patent Document 2 as well, no liquid remains around the ejection port immediately after ejection of the liquid lump held in the liquid holding portion. There is a problem that air is sucked from the discharge port when the pressure member is pulled upward.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a nozzle plate, a liquid ejecting apparatus, and a liquid ejecting method in which air is less likely to be sucked from the ejection openings.

To achieve the above objectives, the present invention includes the subject matter described in the following sections.

Item 1: A nozzle plate having, in a nozzle plate main body, a storage chamber containing a liquid, a discharge channel communicating with the storage chamber, and a discharge port provided at an end of the discharge channel for discharging the liquid. and
a liquid holding portion that holds a liquid film formed to cover the ejection port and is surrounded by a regulating portion that limits the spread of the liquid film;
The nozzle plate, wherein S1/S2 is larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion and S2 is the area of the ejection port when viewed from the plane.

Item 2: The nozzle plate according to Item 1, wherein the liquid holding portion is a depression that is recessed from a position around the liquid holding portion, and the outer side surface of the depression is the regulation portion.

Item 3: The liquid holding portion includes a portion including the ejection port, and an annular recess portion surrounding the portion including the ejection port and recessed beyond the portion including the ejection port. Item 2. The nozzle plate according to Item 1, wherein the side surface is the restriction portion.

Item 4: The portion including the ejection port protrudes from the position around the liquid holding portion,
Item 3, wherein a/b is greater than 0 and equal to or less than 2, where a is a projection length of the portion including the ejection port with respect to the position around the liquid holding portion, and b is the diameter of the ejection port. Nozzle plate as described.

Item 5: The portion including the ejection port is located at the same position as the periphery of the liquid holding portion, or is recessed from the periphery of the liquid holding portion,
Item 3, wherein c/b is not less than -1 and not more than 0, where c is the recessed length of the portion including the ejection port with respect to the position around the liquid holding portion, and b is the diameter of the ejection port. Nozzle plate as described in .

Item 6: The nozzle plate according to Item 1, wherein the liquid retaining portion is a convex portion projecting from a position around the liquid retaining portion, and an end portion of the convex portion is the restricting portion.

Item 7: The liquid holding portion includes an annular protrusion protruding from a position around the liquid holding portion, and a portion including the ejection port protruding from the annular protrusion, and the end portion of the annular protrusion is Item 2. The nozzle plate according to Item 1, which is the restriction portion.

Item 8: further comprising a water-repellent layer having holes for exposing the ejection ports on the lower surface of the nozzle plate main body,
Item 8. The nozzle plate according to any one of Items 1 to 7, wherein the inner surface of the hole of the water-repellent layer is at least part of the regulation portion of the liquid holding portion.

Item 9: The nozzle plate according to any one of Items 1 to 8, wherein the thickness of the liquid film held in the liquid holding portion is five times or less the diameter of the ejection port.

Item 10: A liquid ejection device that ejects liquid by pressurizing the liquid,
A pressure unit, and the nozzle plate according to any one of items 1 to 9 provided at the lower end of the pressure unit,
The pressure unit is
a pressurizing unit body;
a pressurizing member that is supported by the pressurizing unit main body so as to be freely movable in the vertical direction, has a lower end projecting from the pressurizing unit main body, and pressurizes the liquid introduced into the storage chamber to discharge it from the discharge channel;
and a drive unit that vertically moves the pressure member.

Item 11: A liquid ejection method for ejecting the liquid contained in the storage chamber from the ejection port of the ejection channel using the nozzle plate according to any one of Items 1 to 9,
forming and holding a liquid film so as to cover the ejection port;
A step of ejecting a liquid mass composed of part of the liquid film and part of the liquid contained in the storage chamber as a droplet, wherein when the liquid mass separates from the liquid film, the liquid is discharged. ejecting, wherein the membrane remains covering the ejection port;
A method of liquid ejection, comprising:

According to the present invention, it is possible to provide a nozzle plate, a liquid ejecting apparatus, and a liquid ejecting method in which air is less likely to be sucked from ejection ports.

1 is a cross-sectional view showing an overall schematic configuration of a liquid ejection device according to an embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing an enlarged main part of the nozzle plate; It is a bottom view which expands and shows the principal part of a nozzle plate. (A) to (C) are diagrams for explaining a process of ejecting liquid, (A) is a diagram showing a state in which a film of liquid is formed on a liquid holding portion, and (B) is a diagram showing formation of a liquid mass; (C) is a diagram showing a state in which liquid masses are ejected as droplets. FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion; FIG. 10 is a cross-sectional view showing another form of the liquid holding portion;

(overall structure)
An embodiment of the present invention will be described with reference to the drawings. 1 to 4 show a liquid ejection device 10 according to one embodiment of the invention. The liquid ejection device 10 ejects liquid by pressurizing the liquid, and includes a pressurizing section 11 and a nozzle plate 20 provided at the lower end of the pressurizing section 11 . The liquid ejection device 10 is connected to a liquid supply section 100 for supplying liquid to be ejected. In the following description, the vertical direction in FIG. 1 is defined as the vertical direction of the liquid ejection device 10, and the vertical direction is along the axial direction of the ejection passages 22c in the nozzle plate 20, that is, along the direction in which the liquid is ejected. A direction perpendicular to the up-down direction is defined as a left-right direction. However, the vertical direction in this specification does not necessarily correspond to the vertical direction, and the liquid ejection device 10 does not necessarily have to eject liquid along the vertical direction.

(Liquid supply unit 100)
In the liquid supply unit 100 , for example, a syringe 101 storing liquid and an air pressure supply source 103 such as an air compressor for supplying air pressure to the syringe 101 are connected via an electromagnetic valve 102 . When the electromagnetic valve 102 is opened, a predetermined air pressure is supplied from the air pressure supply source 103 into the syringe 101 to push out the liquid, and the liquid is supplied to the liquid ejection device 10 through the liquid supply pipe 105 .

(Liquid ejection device 10)
(Pressure unit 11)
As shown in FIG. 1 , the pressurizing section 11 includes a pressurizing section main body 12 , a pressurizing member 13 , a driving section 14 , and a rotation restricting mechanism 15 . The pressurizing unit main body 12 has a bottomed cylindrical shape with an open upper end, and the opening is closed by a base member 16 . A through hole 12b through which the pressure member 13 is inserted is formed in the central portion of the bottom portion 12a of the pressure portion main body 12 in plan view. A nozzle plate 20 is attached to the outer surface 12c of the bottom portion 12a with screws and screw holes (not shown). A stepped portion 12d in which an O-ring 12e is accommodated is formed around the through-hole 12b on the outer surface 12c of the bottom portion 12a. prevent

The pressurizing member 13 pressurizes the liquid introduced into the concave portion 22 from the liquid channel 23 of the nozzle plate 20, which will be described later, and ejects the liquid from the ejection channel 22c and the ejection port 22d. The pressure member 13 has a cylindrical small diameter portion 13a and a square large diameter portion 13b attached to the upper end of the small diameter portion 13a, and has a T-shaped cross section. Note that the large diameter portion 13b may be cylindrical. The diameter of the small-diameter portion 13a is set so that it can be inserted into the through-hole 12b of the pressurizing portion main body 12. In this embodiment, the diameter of the through-hole 12b is approximately 3.1 mm, and the diameter of the small-diameter portion 13a is approximately 3.0 mm. set, but not limited to this. The small-diameter portion 13 a is inserted through the through hole 12 b , and the lower end projects outward from the outer surface 12 c of the bottom portion 12 a of the pressurizing portion main body 12 and is accommodated in the recess 22 of the nozzle plate 20 . The vertical length of the small-diameter portion 13 a is set to a length sufficient to pressurize the liquid contained in the storage chamber 21 of the recess 22 . On the other hand, the small-diameter portion 13a receives reaction force from the liquid in the storage chamber 21 when pressurized, and shrinks slightly in the vertical direction, and energy loss occurs due to this contraction. Become. From this point of view, the small diameter portion 13a is set as short as possible.

The large-diameter portion 13b is located inside the pressurizing portion main body 12, and the size of the large-diameter portion 13b in plan view is such that the large-diameter portion 13b does not slip out of the through-hole 12b of the pressurizing portion main body 12. is set. An annular disk spring 17 is provided between the lower surface of the large-diameter portion 13b and the upper surface of the bottom portion 12a of the pressurizing portion body 12, and pressurization of the pressurizing member 13 by an actuator 18, which will be described later, is released. In this state, the disc spring 17 urges the pressure member 13 upward to position it at the first position. The pressing member 13 is detachably supported by the pressing portion main body 12 by the disc spring 17 and the through hole 12 b of the pressing portion main body 12 so as to be freely movable in the vertical direction.

A groove-like first channel 19 ( 2) are formed along the vertical direction.

The rotation restricting mechanism 15 restricts the relative rotation of the pressing member 13 about the central axis. The rotation restricting mechanism 15 is composed of, for example, a pin which is a protruding portion protruding from the outer peripheral surface of the small diameter portion 13a of the pressure member 13, and a groove provided on the upper surface of the bottom portion 12a of the pressure portion main body 12 and having an open top. be done. By housing the pin in the groove, the pressure member 13 is restricted from rotating with respect to the recess 22 of the nozzle plate 20 . Note that the rotation restricting mechanism 15 is not limited to this embodiment, and may have a known configuration.

An actuator 18 including a piezoelectric element is attached between the pressure member 13 and the base member 16 . The actuator 18 expands and contracts vertically. The upper surface of the actuator 18 is in contact with the base member 16 by the biasing force of the disc spring 17, and the base member 16 supports the upward reaction force when the actuator 18 is extended.

The actuator 18 contacts the upper surface of the large diameter portion 13b of the pressure member 13, but is not fixed. When the actuator 18 is extended, the lower surface of the actuator 18 contacts the upper surface of the large-diameter portion 13b of the pressure member 13 and applies downward pressure to the pressure member 13 . As a result, the pressing member 13 is moved downward from the first position where it is biased upward by the disc spring 17 against the biasing force of the disc spring 17 to the second position. The moving distance between the first position and the second position is set to about 20 μm, but is not limited to this. The actuator 18 and the disc spring 17 constitute the driving section 14 .

Note that the configuration of the pressurizing unit 11 is not limited to the configuration shown in FIG.

(Nozzle plate 20)
The nozzle plate 20 includes a nozzle plate main body 24, a concave portion 22 having a storage chamber 21 in which liquid is stored, a liquid channel 23 for introducing the liquid into the storage chamber 21, and the liquid stored in the storage chamber 21. It has a discharge channel 22c for discharging, and a discharge port 22d at the lower end of the discharge channel 22c. In this embodiment, the nozzle plate main body 24 includes a first member 31 , a second member 41 joined to the first member 31 in a separable manner, and a cushioning member 50 . As shown in FIG. 1, the first member 31 and the second member 41 are freely separably joined via a cushioning member 50 by joining means such as a screw (not shown).

(First member 31)
As shown in FIG. 1 , the first member 31 has a rectangular shape in plan view, and the right portion 32 is formed to have a smaller thickness (vertical length) than the left portion 33 . The upper surface of the right portion 32 is attached to the outer surface 12c of the bottom portion 12a of the pressurizing portion main body 12 of the pressurizing portion 11 . The thickness of the right portion 32 of the first member 31 is formed as thin as possible in order to shorten the length of the small diameter portion 13a of the pressure member 13 in the vertical direction. It is not limited to this. The left portion 33 is set to 3000 μm in this embodiment, but is not limited to this.

A joint portion 34 for connecting with the liquid supply portion 100 is provided on the upper surface of the left portion 33 . A connection channel 34 a is formed inside the joint part 34 , and communicates with an introduction channel 35 provided in the first member 31 along the vertical direction. In the first member 31 , recess through holes 36 forming the recesses 22 are formed along the vertical direction at positions corresponding to the through holes 12 b of the pressure unit body 12 . The recess through-hole 36 has a circular shape when viewed from a plane. The diameter of the recess through-hole 36 is set to be smaller than the diameter of the through-hole 12b of the pressure member body 12 and slightly larger than the diameter of the small-diameter portion 13a so that the small-diameter portion 13a of the pressure member 13 can be inserted. ing.

A groove 37 is formed in the lower surface 31 a of the first member 31 so as to communicate with the recess through-hole 36 and the introduction channel 35 . The groove 37 has a semicircular cross-sectional shape, and the bottom side of the groove 37 is open. In the present embodiment, the introduction channel 35, the groove 37, and the recess through-hole 36 are positioned on a straight line in plan view. When the first member 31 and the second member 41 are joined, the groove 37 becomes part of the liquid flow path 23 by closing the open portion with the buffer member 50 and the second member 41 . The groove 37 , the introduction channel 35 and the connection channel 34 a constitute the liquid channel 23 . In this embodiment, the length of the groove 37 in the horizontal direction in FIG. 1 is about 10000 μm (10 mm), the length (thickness) of the groove 37 in the vertical direction in FIG. The length (width) in the direction orthogonal to the thickness and thickness is set to about 1400 μm, but is not limited to this. A lower surface 31a of the first member 31 is a surface to be joined to the second member 41 and is also called a joint surface 31a.

The first member 31 is preferably made of a highly rigid material such as metal or ceramic. Although it is made of stainless steel in this embodiment, it is not limited to this, and may be made of ceramic such as alumina or zirconia.

(Second member 41)
The second member 41 has a rectangular shape, and the upper surface 41a is a bonding surface 41a that is bonded to the lower surface of the first member 31 with the cushioning member 50 interposed therebetween. A joint surface 41 a of the second member 41 is formed with a recess hole 42 forming the recess 22 at a position corresponding to the recess through hole 36 of the first member 31 . The recess hole 42 has a circular shape when viewed from the plane, and the diameter of the recess hole 42 is set to be the same as the diameter of the recess through hole 36 . The small-diameter portion 13 a of the pressure member 13 passing through the through hole 12 b of the pressure member main body 12 passes through the recess 22 formed by the through hole 36 for the recess of the first member 31 and the hole 42 for the recess of the second member 41 . A lower end is accommodated. In the present embodiment, the shortest distance between the outer peripheral surface 13c of the small diameter portion 13a of the pressure member 13 and the inner surface 22b of the recess 22 is set to about 5 μm, but it is not limited to this. Between the bottom surface 13d of the pressurizing member 13 and the bottom portion 22a of the recess hole 42, a storage chamber 21 is formed in which liquid is stored.

As shown in FIG. 2, a discharge flow path 22c for discharging the liquid stored in the storage chamber 21 of the recess 22 is formed in the bottom 22a of the recess hole 42. As shown in FIG. The discharge channel 22c is circular in plan view, and has a tapered shape with an inner diameter that decreases toward the bottom. The discharge channel 22c is located at a position deviated from the center of gravity P of the recess 22 in plan view, and corresponds to the liquid channel 23 formed in the first channel 19 of the pressure member 13 and the inner surface 22b of the recess 22 in FIG. is formed on the opposite side of the center of gravity position P from the opening of . In this embodiment, since the concave portion 22 is circular in plan view, the center point of the circular shape is the center of gravity position P. As shown in FIG. As a result, the liquid supplied from the first flow path 19 of the pressurizing member 13 is supplied to the entire storage chamber 21, and air pooling is less likely to occur in the storage chamber 21, thereby preventing ejection failure. Note that the position of the discharge channel 22c is not limited to that of the present embodiment, and may be any position on the bottom 22a of the recess 22. FIG.

The thickness of the second member 41, that is, the length in the vertical direction, is determined by the pressure exerted by the pressure member 13 on the liquid contained in the storage chamber 21 during the liquid discharge operation. The thickness is set to the extent that bending does not occur. On the other hand, the thickness of the second member 41 is set as thin as possible from the viewpoint of shortening the small diameter portion 13a of the pressure member 13 as much as possible.

The second member 41 is preferably made of a highly rigid material such as metal or ceramic. Although it is made of stainless steel in this embodiment, it is not limited to this, and may be made of ceramic such as alumina or zirconia. Moreover, it is preferable to be made of the same material as the first member 31 .

(Liquid holding portion 60)
A liquid holding portion 60 is formed on the lower surface 41 b of the second member 41 . The liquid holding portion 60 holds a liquid film M formed so as to cover the ejection port 22d positioned at the lower end of the ejection channel 22c, and is surrounded by a restricting portion 61 that restricts the spread of the liquid film M. is As shown in FIGS. 2 and 3, the liquid holding portion 60 has a circular shape when viewed from the top, and is recessed upward from a position around the liquid holding portion 60 (that is, the lower surface 41b of the second member 41). It is a recessed part. At the center of the bottom surface 60a of the liquid holding part 60 in a plan view, an ejection port 22d having a circular shape when viewed from the plan is opened. In the case of this embodiment, the restricting portion 61 is the end portion of the recessed portion, that is, the outer side surface 60b (peripheral wall) of the recessed portion. S1/S2 is set to be larger than 25 and smaller than 2500, preferably larger than 100 and 625, where S1 is the area of the bottom surface 60a of the liquid holding portion 60 and S2 is the area of the ejection port when viewed from the plane. set smaller. In calculating S1/S2, the area S1 of the bottom surface 60a of the liquid holding portion 60 is the area of a circle having the inner diameter L1 of the liquid holding portion 60 as its diameter, and includes the area S2 of the ejection port.

2 and 4(A), at least immediately before the step of ejecting the liquid onto the workpiece, which is the object to be ejected (also referred to as "liquid ejection operation"). A membrane M is held. The liquid film M adheres to and is held by the bottom surface 60a of the liquid holding portion 60 and the regulation portion 61 due to surface tension. The thickness d of the liquid film M is set to be 1 to 5 times the diameter b of the ejection port 22d. The thickness d of the liquid film M is the length of the liquid film M along the vertical direction passing through the center of the ejection port 22d. In other words, it is the minimum length between the center of the outlet 22d and the outer surface of the membrane. The step of ejecting the liquid does not include ejection for checking the ejection amount C1 (volume) per shot, which is called a so-called trial ejection (also referred to as trial ejection). On the other hand, it means to perform an operation of ejecting liquid at a predetermined ejection amount C1 per one time.

The volume of the liquid contained in the film M when the liquid film M is formed (also referred to as the “volume of the liquid film M”) C2 is determined by the type of liquid and the desired liquid ejection amount C1 (volume ), etc. The liquid ejected by the liquid ejecting apparatus 10 of the present embodiment is not particularly limited, but it is preferable that the viscosity of the liquid does not easily change even after a predetermined period of time has passed when the liquid is held as the film M in the liquid holding portion 60 . At least during the liquid ejection operation, a liquid having a viscosity in the range of 0.001 Pa·s or more and 2 Pa·s or less is preferably used. mentioned. Further, a predetermined discharge amount C1 of the liquid per one time is set to 1 nanoliter (1×10 ⁻¹² cubic meters) or more and 200 nanoliter or less. Note that the liquid to be ejected may have a viscosity within the above range during the liquid ejection operation. For example, even if the liquid has a viscosity outside the above range at room temperature, the nozzle plate 20 is provided with a heater to heat the liquid, and the liquid is brought to a predetermined temperature during the liquid ejection operation so that the viscosity falls within the above range. Inner liquid may be used.

C2/C1 is preferably set to 20 or more and 900 or less, more preferably 30 or more, where C1 is the liquid ejection amount (volume) per one time discharge and C2 is the volume of the liquid film M. , 300 or less.

The depth L2 (length in the vertical direction) of the liquid holding portion 60 is set according to the desired volume C2 of the liquid film M. /L1 is set to 0.01 or more and 0.1 or less.

In this embodiment, the inner diameter of the ejection port 22d is 200 μm, the thickness d of the liquid film M is 200 μm, the inner diameter L1 of the liquid retaining portion 60 is 3 mm, and the depth L2 of the liquid retaining portion 60 is 0.05 mm. is set to 30 nanoliters (30×10 ⁻¹² cubic meters), and the volume C2 of the liquid film M is set to 1500 nanoliters.

Methods for forming the liquid film M include, for example, a method of throwing away the liquid and a method of supplying the liquid from the liquid supply unit 100 . In the method of using the dummy shot, the dummy shot is ejected several times to several tens of times before the liquid is ejected onto the workpiece. In a normal liquid ejection operation, the liquid supply unit 100 supplies the liquid in the ejection amount C1 per ejection to the storage chamber 21 for each ejection. The amount of liquid larger than the ejection amount C1 is supplied to the storage chamber 21 for each ejection. Then, the liquid overflowing from the storage chamber 21 comes out from the ejection port 22d and is held around the ejection port 22d. When a dummy ejection is performed in this state, part of the liquid discharged from the storage chamber 21 and part of the liquid held around the ejection port 22d are combined to be ejected as droplets. Not all the liquid held around is ejected as droplets, but the liquid remains around the ejection port 22d. By repeating the random ejection and the liquid supply from the liquid supply unit 100, the amount of liquid held around the ejection port 22d gradually increases, and is held along the bottom surface 60a of the liquid holding unit 60 by surface tension. It spreads while being done. When the liquid reaches the regulating portion 61 , the liquid thickens vertically along the regulating portion 61 and forms a liquid film M on the liquid retaining portion 60 . The amount of liquid supplied from the liquid supply unit 100 required to form the liquid film M and the number of times of discarding discharge are determined by the inner diameter L1 and depth L2 of the liquid holding unit 60 and the volume C2 of the desired liquid film M. , is determined by the thickness d of the liquid film M and is controlled by the controller.

In the method of supplying from the liquid supply unit 100, the liquid is supplied from the liquid supply unit 100 into the storage chamber 21, thereby discharging the liquid already existing in the storage chamber 21 or the liquid supplied from the liquid supply unit 100. A liquid film M is formed by leaking from the outlet 22d. The amount of liquid supplied by the liquid supply unit 100 required to form the liquid film M is determined by the inner diameter L1 and depth L2 of the liquid holding unit 60 and the volume C2 of the liquid film M, and is controlled by the control unit. .

(buffer member 50)
As shown in FIG. 1, the first member 31 and the second member 41 are joined with the cushioning member 50 interposed therebetween. Joining the first member 31 and the second member 41 in a separable manner includes joining the first member 31 and the second member 41 through the cushioning member 50 . The cushioning member 50 is sheet-like, has a shape and size corresponding to the first member 31 and the second member 41 in a plan view, is made of PET (polyethylene terephthalate), and has a thickness of 50 μm. It is flexible. As shown in FIG. 1 , recessed through holes 51 are formed in the cushioning member 50 at positions corresponding to the recessed through holes 36 of the first member 31 and the recessed holes 42 of the second member 41 . At least the upper surface 50a of the cushioning member 50 facing the joint surface 31a of the first member 31 is subjected to mold release treatment. The mold release process is a process to make the cushioning member 50 easily peeled off from at least the first member 31, for example, a process of applying a mold release agent to the surface.

In this embodiment, PET (polyethylene terephthalate) is used as a rigid resin sheet as a material for the cushioning member 50, but PP (polypropylene) is also preferably used as a material with good low adhesion. Metals such as stainless steel and aluminum can also be used, in which case a thickness of 10 μm to 30 μm is preferably used from the viewpoint of flexibility. By providing the buffer member 50 between the first member 31 and the second member 41, the liquid enters between the first member 31 and the second member 41 and solidifies, and the first member 31 and the second member 41 are stuck together and cannot be separated. In addition, in this embodiment, the structure which does not have the buffer member 50 may be sufficient.

Note that the nozzle plate 20 is not limited to this embodiment, and is connected to the liquid supply section 100. The liquid supplied from the liquid supply section 100 is introduced into the storage chamber 21, discharged from the discharge port 22d, and discharged from the liquid holding section. 60 may be any known nozzle. For example, the nozzle plate 20 may not be separated into the first member 31 and the second member 41, but may be configured as one member, and the cushioning member 50 may not be provided.

(control part)
A control section (not shown) is connected to each section such as the actuator 18 and the electromagnetic valve 102 of the liquid supply section 100 . The control unit includes a memory, a CPU, etc., in which programs necessary for the operation of each unit are stored in advance, and the CPU executes various programs to control the operation of each unit. Accordingly, the liquid ejection device 10 operates.

(Liquid Ejecting Method by Liquid Ejecting Apparatus 10)
A liquid ejection method by the liquid ejection apparatus 10 of this embodiment will be described. As a preparatory step, an operation of supplying liquid from the liquid supply unit 100 to the storage chamber 21 is performed. The electromagnetic valve 102 of the liquid supply unit 100 is opened by the control unit, and a predetermined air pressure is supplied from the air pressure supply source 103 into the syringe 101 to push out the liquid from the syringe 101 and discharge the liquid through the liquid supply pipe 105. Liquid flows through the liquid channel 23 of the nozzle plate 20 of the device 10 into the reservoir 21 of the recess 22 . When a predetermined amount of liquid is supplied to the storage chamber 21, the controller closes the electromagnetic valve 102. FIG. Also, the control unit operates the actuator 18 to position the pressure member 13 at the first position.

Next, a step of forming and holding a liquid film M on the liquid holding portion 60 is performed. In the case of the method using dummy shots, dummy shots are ejected several times to several tens of times before the step of ejecting the liquid to be described later, that is, before the liquid ejection operation to the workpiece. As a result, a liquid film M is formed on the liquid holding portion 60 so as to cover the ejection port 22d by surface tension. At this time, it is preferable that the control unit controls the number of times and the amount of ejection so that the thickness d of the liquid film M is five times or less the diameter b of the ejection port 22d. FIG. 4A shows the liquid film M held in the liquid holding section 60 . In the case of the method of supplying from the liquid supply unit 100, by supplying the liquid from the liquid supply unit 100 into the storage chamber 21, the liquid already existing in the storage chamber 21 or the liquid supplied from the liquid supply unit 100 A liquid film M is formed by leaking the liquid from the ejection port 22d. Due to the surface tension of the liquid film M, the controller preferably adjusts the amount of liquid supplied by the liquid supply unit 100 so that the thickness d of the liquid film M is five times or less the diameter b of the ejection port 22d. In the case of the method of supplying from the liquid supply unit 100, the process of forming and holding the liquid film M may be performed simultaneously with the above-described preparation process. S1/S2 is set to be larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion 60 and S2 is the area of the ejection port 22d. , and is formed so as to cover the ejection port 22d.

Then, a step of ejecting liquid is performed. The actuator 18 moves the pressing member 13 downward from the first position to the second position. As a result, the liquid stored in the storage chamber 21 is pressed by the pressurizing member 13, and the amount of liquid corresponding to the amount of movement of the actuator 18 is discharged from the discharge port 22d through the discharge passage 22c. At this time, the amount of liquid coming out of the ejection port 22d is less than the predetermined liquid ejection amount C1. When the liquid ejected from the ejection port 22d is added to the liquid film M, the liquid film M cannot be held by the liquid holding portion 60, and a downward liquid mass B1 is formed as shown in FIG. 4B. The liquid mass B1 is a combination of part of the liquid film M held in the liquid holding unit 60 in advance before the liquid exits from the ejection port 22d and part of the liquid ejected from the ejection port 22d. Then, as shown in FIG. 4C, the liquid mass B1 is ejected as a droplet B2 separated from the liquid film M. As shown in FIG. In the present embodiment, S1/S2 is larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion 60 and S2 is the area of the ejection port 22d. The volume C2 of the liquid film M held in the liquid holding part 60 is set such that the thickness d of the film M is five times or less the diameter of the ejection port. The applicant found that the volume of the ejected droplet B2 becomes equal to the predetermined liquid ejection amount (volume) C1 per one time by setting in this manner. It should be noted that the fact that the volume of the ejected droplet B2 is equal to the predetermined amount of liquid ejected per one time C1 means that the volume of the droplet B2 (the volume of the liquid actually ejected per one time) is equal to the volume. Including cases where it is 90% or more and 110% or less of C1.

The volume C2 of the liquid film M is set to be sufficiently larger than the ejection amount (volume) C1 of the liquid per one time, and when the droplet B2 is ejected, the volume of the liquid held in the liquid holding portion 60 is increased. Not all of the film M is ejected as droplets B2, but only part of it is ejected as droplets B2. Therefore, when the liquid mass B1 is separated from the liquid film M and the droplet B2 is ejected, the liquid holding unit 60 maintains the liquid film M, and the ejection port 22d holds the liquid. It is covered with a membrane M.

The actuator 18 begins to contract immediately after the liquid contained in the storage chamber 21 is pressed and the liquid begins to flow out from the discharge port 22d, and the pressure member 13 is pushed up by the biasing force of the disc spring 17 to reach the first position. back to Since the ejection port 22d is covered with the liquid film M, air does not enter the ejection channel 22c from the ejection port 22d even when the pressure member 13 is pushed up.

After the step of ejecting the liquid described above, the liquid supply step of supplying the same amount of liquid as the amount C1 to be ejected next from the liquid supply unit 100 to the storage chamber 21 is performed. The liquid supply process is the same operation as the liquid supply operation in the preparation process. A portion of the liquid supplied by the liquid supply operation is stored in the storage chamber 21 . The remaining liquid leaks out from the ejection port 22d and becomes a part of the liquid film M, and the thickness d of the liquid film M becomes substantially the same as the thickness d of the liquid film M immediately before the step of ejecting the liquid. . That is, the liquid film M returns to the state shown in FIG. 4(A). The step of ejecting the liquid and the step of supplying the liquid are alternately repeated.

In the present embodiment, in the step of ejecting the liquid, for example, by moving the pressure member 13 downward from the first position to the second position by the actuator 18, predetermined liquid is ejected from the ejection port 22d. Assume that the amount of liquid (C1/2) that is half the ejection amount is ejected. Then, C1/2 of the liquid discharged from the ejection port 22d and C1/2 of the liquid film M held in advance in the liquid holding unit 60 before the liquid was discharged from the ejection port 22d. The amount of liquid is combined to form droplets B2 of the amount of C1, which are ejected. Next, in the liquid supply step, when the amount of liquid C1 is supplied from the liquid supply unit 100 to the storage chamber 21, the amount of liquid of C1/2 is stored in the storage chamber 21, and the remaining amount of C1/2 is stored in the storage chamber 21. The liquid leaks out from the ejection port 22d and becomes part of the liquid film M. As shown in FIG. In this way, by repeating the step of ejecting the liquid and the step of supplying the liquid, the amount of liquid C1 is ejected as droplets B2.

In the present embodiment, the liquid film M is formed on the liquid holding portion 60 so as to cover the ejection port 22d. S1/S2 is set to be larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion 60 and S2 is the area of the ejection port 22d. Further, the thickness d of the liquid film M immediately before the liquid ejection operation is set to be five times or less the diameter b of the ejection port 22d. According to the applicant, with this configuration, when the droplets B2 are ejected, the liquid film M held in the liquid holding unit 60 is not entirely ejected as the droplets B2, but only a part of the liquid film M is ejected. is combined with part of the liquid ejected from the ejection port 22d to be ejected as a droplet B2. Therefore, when the droplet B2 is ejected, the liquid film M is held by the remaining liquid in the liquid holding portion 60, and the ejection port 22d remains covered with the liquid film M. Therefore, immediately after the droplet B2 is ejected, there is no air around the ejection port 22d, and the pressure member 13 sucks air when it moves upward to the first position. is prevented, and stable liquid ejection becomes possible.

In the conventional technology, it is generally desirable that no liquid remains around the ejection port 22d. In general, when a liquid ejecting apparatus performs a liquid ejecting operation, liquid adheres around the ejection port 22d due to a liquid shortage. Liquid shortage means that although the liquid ejected from the ejection port 22d jumps out of the ejection port 22d, part of the liquid is completely separated from the ejection port 22d and remains around the ejection port 22d. By repeating the liquid ejection operation, the amount of liquid attached around the ejection port 22d gradually increases. If liquid adheres to the periphery of the ejection port 22d, the liquid ejected from the ejection port 22d hits the adhered liquid, causing an ejection failure such as the liquid flying obliquely when ejected downward or the liquid breaking and scattering. Sometimes. For this reason, normally, the liquid ejection operation is stopped every predetermined number of times of ejection, and the surroundings of the ejection port 22d are cleaned to remove the adhering liquid as dirt.

On the other hand, in the present embodiment, since the ejection port 22d is covered with the liquid film M in the step of ejecting the liquid, the liquid does not adhere to the periphery of the ejection port 22d as dirt as in the prior art. do not have. Therefore, droplets are ejected in the vertical direction, the liquid is prevented from scattering, and the liquid can be ejected stably.

Moreover, due to the difference in head pressure between the storage chamber 21 and the liquid supply unit 100, the liquid in the storage chamber 21 may spontaneously leak out from the discharge port 22d. In the prior art, when the interval between the liquid ejection operation and the next liquid ejection operation is long, for example, about 5 seconds, the amount of liquid leaking from the ejection port 22d increases and adheres to the periphery of the ejection port 22d. Increased amount of liquid. When the liquid ejecting operation is performed after a large amount of liquid has adhered, the liquid ejected from the ejection port 22d is combined with the liquid adhering around the ejection port 22d to form droplets B2 that are ejected. The volume of the droplet B2 may be larger than the ejection amount C1 per ejection. However, according to this embodiment, the liquid holding portion 60 always maintains the state in which the liquid film M is held. It becomes part of the membrane M. Although the volume C2 of the liquid film M increases due to the addition of the leaked liquid, the increase in the volume C2 of the liquid film M due to the addition of the leaked liquid to the existing liquid film M is small. Therefore, the volume of the ejected droplets B2 is less affected by the liquid leaking from the ejection port 22d, and the volume of the droplets B2 does not increase significantly as compared with the conventional technology.

(Another Embodiment of Liquid Discharging Process and Liquid Supplying Process)
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. For example, the liquid ejection process and the liquid supply process are not limited to the above methods. In the above process, after the electromagnetic valve 102 is opened to supply the liquid from the liquid supply unit 100 to the storage chamber 21, the electromagnetic valve 102 is closed to perform the liquid ejection operation. That is, the electromagnetic valve 102 is opened and closed for each liquid supply operation. However, the process is not limited to this process. For example, with the electromagnetic valve 102 open, the liquid ejection operation is performed by repeating the reciprocating motion of the pressure member 13 between the first position and the second position. good too. According to this method, since it is not necessary to open and close the electromagnetic valve 102, the droplets B2 can be discharged quickly and continuously a plurality of times, and the discharge cycle can be shortened.

(Another embodiment of the liquid holding part 60)
Another embodiment of the liquid holding part 60 is shown in FIG. The liquid holding portion 60 has a portion 62 including an ejection port and an annular recess portion 63 . The portion 62 including the ejection port is a circular flat surface when viewed from the top, has an ejection port 22 d opening in the center, and protrudes downward from the position around the liquid holding portion 60 . In other words, in FIG. 5 , the portion 62 including the ejection port is positioned below the bottom surface 41 b of the second member 41 . The annular recessed portion 63 surrounds the portion 62 including the discharge port, and recesses above the lower surface 41 b of the second member 41 at a position around the liquid holding portion 60 . The projection length of the portion 62 including the ejection port with respect to the position around the liquid holding portion 60 is a (the downward direction is positive, and the projection length a is always a positive value), and the diameter of the ejection port 22d is b. Sometimes a/b is set to be greater than 0 and less than or equal to 2. In the present embodiment, the inner diameter L1 of the liquid holding portion 60 is the diameter (outer diameter) of the outer side surface 60b of the annular recessed portion 63, and the diameter of the portion 62 including the discharge port is L3, then L3/L1 is: It is set to 0.1 or more and 0.3 or less. An outer side surface 60 b (peripheral wall) of the annular recessed portion 63 constitutes a restricting portion 61 . A depth L<b>4 of the annular recessed portion 63 is the distance between the bottom surface 63 a of the annular recessed portion 63 and the lower surface 41 b of the second member 41 .

In the process of forming and holding the liquid film M in the liquid holding portion 60, the liquid coming out of the ejection port 22d spreads over the portion 62 including the ejection port and reaches the outer edge of the portion 62 including the ejection port. Spreading of the liquid is regulated by the outer edge of the portion 62 including the ejection port, and a liquid film M is once formed on the portion 62 including the ejection port. If the volume of the liquid contained in the liquid film M further increases, it cannot be retained in the portion 62 including the ejection port. As a result, the liquid flows over the outer edge of the portion 62 including the ejection port and reaches the inner side surface 63b of the annular recess 63 (the side surface 63b caused by the vertical position difference between the bottom surface 63a of the annular recess 63 and the portion 62 including the ejection port). ) and along the bottom surface 63 a of the annular recess 63 . When reaching the restricting portion 61, which is the outer side surface 60b of the annular recessed portion 63, further outward spread is restricted, and the liquid is retained so that the liquid film M becomes thicker in the vertical direction, and surface tension is applied. A liquid film M is formed by . The thickness d of the liquid film M is the minimum length between the center of the ejection port 22d and the outer surface of the film. Further, the area S1 of the liquid holding portion 60 is the area of a circle having the inner diameter L1 of the liquid holding portion 60 as its diameter, and the area of the portion 62 including the ejection port when viewed from the plane (diameter L3 of the portion 62 including the ejection port). area of a circle with a diameter of ). Since other configurations are the same as those of the embodiment of FIG. 1, descriptions thereof will be omitted by assigning the same reference numerals to corresponding portions.

According to the above configuration, the liquid film M having the desired volume C2 can be formed in the liquid retaining section 60 by adjusting the depth L4 of the annular recessed section 63 . Also, the thickness d of the liquid film M in the portion 62 including the ejection port can be reduced. Since the thickness d of the liquid film M in the portion 62 including the ejection port is thin and the annular recess 63 is positioned above the portion 62 including the ejection port, part of the liquid coming out of the storage chamber 21 is A portion of the liquid film M covering the portion 62 including the ejection port is combined to form a liquid mass B1, and the liquid in the annular recess 63 is not included in the liquid mass B1. Therefore, even if the liquid mass B1 is ejected, the liquid in the annular recess 63 remains in the liquid holding portion 60 without fail, and immediately after the liquid is ejected, it moves to the portion 62 including the ejection port to cover the ejection port 22d. A liquid film M can be formed.

FIG. 6 shows another embodiment of the liquid holding part 60. As shown in FIG. Only points different from the embodiment of FIG. 5 will be described below. An end portion 62a of the portion 62 including the ejection port of the liquid holding portion 60 is chamfered in an arcuate cross section and is continuous with the inner side surface 63b of the annular recess portion 63 . The radius of curvature of the end portion 62a is 0.1 or more and 3 or less. In addition, the restricting portion 61, that is, the outer side surface 60b of the annular recessed portion 63 is inclined obliquely with respect to the vertical direction in cross section. The outer diameter of the annular recessed portion 63 increases downward, and the maximum diameter of the outer side surface 60b of the annular recessed portion 63 is defined as the inner diameter L1 of the liquid holding portion 60 . Since other configurations are the same as those of the embodiment of FIG. 5, descriptions thereof are omitted by assigning the same reference numerals to the corresponding portions.

If the end portion 62a of the portion 62 including the ejection port is not chamfered, in the step of forming and holding the liquid film M in the liquid holding portion 60, the spreading of the liquid is once restricted by the end portion 62a and the ejection is not performed. A liquid film M is formed in the portion 62 containing the outlet. As the volume of the film M of liquid increases further, the liquid spreads into the annular recess 63 beyond the edge 62a. However, according to the above-described embodiment, since the end 62a of the portion 62 including the ejection port is chamfered in an arc shape, the spreading of the liquid in the portion 62 including the ejection port is not restricted by the end 62a. It tends to spread along the inner side surface 63b of the annular recessed portion 63 and the bottom surface 63a of the annular recessed portion 63 from the outer edge of the portion 62 including the discharge port.

In the embodiment shown in FIG. 6, at least one of the end portion 62a of the portion 62 including the ejection port of the liquid holding portion 60 and the regulating portion 61 has the shape of the embodiment shown in FIG. may have the same form as the embodiment shown in FIG. 7 to 12 to be described later, at least one of the shape of the end portion 62a of the portion 62 including the discharge port and the direction in which the restricting portion 61, which is the outer side surface 60b of the annular recess portion 63, extends. may be of the same form as the embodiment of FIG.

Another embodiment of the liquid holding part 60 is shown in FIG. In the embodiment of FIG. 7, a water-repellent layer 66 is formed on the lower surface 41b of the second member 41 of the nozzle plate body 24. As shown in FIG. The water-repellent layer 66 has a hole 66a for exposing the outlet 22d and the annular depression 63. As shown in FIG. The hole 66a is circular in plan view and has the same shape as the lower end of the outer side surface 60b of the annular recess 63. Contiguous. The hole 66a forms part of the liquid holding portion 60. As shown in FIG. An inner surface 66b of the hole 66a is a part of the regulating portion 61 of the liquid holding portion 60, and constitutes the regulating portion 61 of the liquid holding portion 60 together with the outer side surface 60b of the annular recess portion 63. As shown in FIG. The water-repellent layer 66 is composed of, for example, a fluorine-based water-repellent agent, and is formed by a known coating method or plating method. In the coating method, the thickness of the water-repellent layer 66 is often 0.001 μm or more and 0.02 μm or less, and in the plating method, the thickness is often 2 μm or more and 20 μm or less. However, the material and thickness of the water-repellent layer 66 are not limited to those of this embodiment. Other configurations are the same as those in the embodiment of FIG. 6, so corresponding parts are denoted by the same reference numerals and descriptions thereof are omitted.

According to the present embodiment shown in FIG. 7, since the water-repellent layer 66 is formed on the lower end of the regulating portion 61, the surface of the liquid film M is located on the inner surface 66b of the hole 66a of the water-repellent layer 66. Sometimes, the water-repellent power of the water-repellent layer 66 acts on the surface tension of the film M of liquid. Therefore, the volume C2 of the liquid film M that can be held by the liquid holding section 60 can be increased. The water-repellent layer 66 may be provided on the nozzle plate 20 of the embodiments shown in FIGS. 1 to 5 and the embodiments shown in FIGS. 8 and 9 described later.

FIG. 8 shows another embodiment of the liquid holding part 60. As shown in FIG. A portion 62 including the ejection port of the liquid holding portion 60 is located around the liquid holding portion 60, that is, at the same position as the lower surface 41b of the second member 41, and has the same height in the vertical direction. Since other configurations are the same as those of the embodiment of FIG. 5, descriptions thereof are omitted by assigning the same reference numerals to the corresponding portions. According to the embodiment shown in FIG. 8, the liquid holding portion 60 can be formed simply by cutting the lower surface 41b of the second member 41 of the nozzle plate 20 so as to form the annular recess portion 63. It is easy to process when forming.

Another embodiment of the liquid holding part 60 is shown in FIG. A portion 62 including the ejection port of the liquid holding portion 60 is recessed from the surrounding position of the liquid holding portion 60 . In other words, in FIG. 9 , the portion 62 including the ejection port is positioned above the bottom surface 41 b of the second member 41 . The recessed length of the portion 62 including the ejection port with respect to the position of the liquid holding portion 60 is c (the downward direction is positive, and the recessed length c always takes a negative value), and the diameter of the ejection port 22d is b. Sometimes, c/b is set to be greater than or equal to -1 and less than or equal to 0. Note that when c/b is 0, the embodiment shown in FIG. 8 is obtained. Since other configurations are the same as those of the embodiment of FIG. 5, descriptions thereof are omitted by assigning the same reference numerals to the corresponding portions.

FIG. 10 shows another embodiment of the liquid holding portion 60. As shown in FIG. The liquid holding portion 60 is a convex portion that protrudes from the position around the liquid holding portion 60 . That is, the liquid holding portion 60 protrudes below the lower surface 41 b of the second member 41 . An end (outer edge) of the convex portion constitutes a restricting portion 61 . The liquid discharged from the ejection port 22d spreads on the lower surface 60c of the liquid holding portion 60, and when it reaches the outer edge, the liquid is prevented from spreading further outward by surface tension so as to cover the lower surface 60c of the liquid holding portion 60. A membrane M is formed. Since other configurations are the same as those of the embodiment of FIG. 1, descriptions thereof will be omitted by assigning the same reference numerals to corresponding portions. In addition, in FIG. 10, the lower surface 60c of the liquid holding portion 60 is a flat surface, but it may be a curved surface that is convex downward.

FIG. 11 shows another embodiment of the liquid holding portion 60. As shown in FIG. The liquid holding portion 60 includes an annular protrusion 64 protruding from the periphery of the liquid holding portion 60 and a portion 65 surrounded by the annular protrusion 64 and including an ejection port protruding from the annular protrusion 64 . That is, the annular protrusion 64 protrudes downward from the lower surface 41b of the second member 41, and the portion 65 including the discharge port protrudes downward from the annular protrusion 64 by the protrusion length e. An end portion (outer edge) of the annular convex portion 64 constitutes the restricting portion 61 . The liquid coming out of the ejection port 22d spreads over the portion 65 including the ejection port and reaches the outer edge of the portion 65 including the ejection port. Then, it spreads along the side surface caused by the vertical position of the annular convex portion 64 and the portion 65 including the ejection port, and when it reaches the restricting portion 61 which is the outer edge of the annular convex portion 64, it spreads further outward. A regulated, liquid film M is formed by surface tension. Since other configurations are the same as those of the embodiment of FIG. 1, descriptions thereof will be omitted by assigning the same reference numerals to corresponding portions.

12 shows another embodiment of the liquid holding part 60. As shown in FIG. In the embodiment of FIG. 12, like the embodiments of FIGS. 1 to 11, the lower surface 41b of the second member 41 of the nozzle plate body 24 is provided with a depression, an annular depression 63, an annular protrusion 64, and the like. The lower surface 41b is a flat surface, and the ejection port 22d is open. A water-repellent layer 66 is formed on the lower surface 41 b of the second member 41 . The water-repellent layer 66 has holes 66a for exposing the ejection ports 22d. The hole 66a is circular in plan view and has a diameter larger than the diameter b of the discharge port 22d. The inside of the hole 66 a constitutes the liquid holding portion 60 , and the inner surface 66 b of the hole 66 a becomes the regulation portion 61 of the liquid holding portion 60 . The water-repellent layer 66 is composed of, for example, a fluorine-based water-repellent agent, and is formed by a known coating method or plating method. In the coating method, the thickness of the water-repellent layer 66 is often 0.001 μm or more and 0.02 μm or less, and in the plating method, the thickness is often 2 μm or more and 20 μm or less. However, the material and thickness of the water-repellent layer 66 are not limited to those of this embodiment. Since other configurations are the same as those of the embodiment of FIG. 1, descriptions thereof will be omitted by assigning the same reference numerals to corresponding portions.

In the above embodiment, the nozzle plate 20 can be provided with the liquid holding portion 60 by a simple process of forming the water-repellent layer 66 having the holes 66a on the lower surface 41b of the nozzle plate main body 24, which is a flat surface. .

The dimensions, materials, shapes, relative positions, and the like of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained. For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state. For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. The shape including the part etc. shall also be represented. References to "comprise," "comprise," "comprise," "include," or "have" an element are not exclusive expressions that exclude the presence of other elements.

In addition, in this specification, expressions such as "end" and "end" are used to distinguish between the presence or absence of "... portion". For example, "end" means a portion having a certain range including the "end". The same applies to other expressions with "... part".

10 liquid ejection device 11 pressurizing part 21 storage chamber 22c ejection passage 22d ejection port 24 nozzle plate main body 60 liquid holding portion 61 regulation portion 62 portion including ejection port 63 annular depression 64 annular convex portion 65 portion 66 including ejection port Water-repellent layer M Liquid film S1 Area of liquid holding portion S2 Area of ejection port C1 Ejection amount of liquid per one time C2 Volume of liquid film a Protrusion length of portion including ejection port b Diameter of ejection port c Ejection Invagination length of the part containing the outlet d Thickness of the liquid film

Claims (9)

A nozzle plate having, in a nozzle plate main body, a storage chamber in which liquid is stored, a discharge channel communicating with the storage chamber, and a discharge port provided at an end of the discharge channel for discharging the liquid. ,
a liquid holding portion that holds a liquid film formed to cover the ejection port and is surrounded by a regulating portion that limits the spread of the liquid film;
The ejection port having a circular shape when viewed from a plane opens in the center of the liquid holding portion,
the liquid holding portion is a depression that is recessed from a position around the liquid holding portion, and the outer side surface of the depression is the regulation portion;
S1/S2 is larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion and S2 is the area of the ejection port when viewed from the plane,
the thickness of the liquid film held in the liquid holding portion is five times or less the diameter of the ejection port;
C2/C1 is set to 20 or more and 900 or less, where C1 is the discharge amount (volume) of the liquid per one time, and C2 is the volume of the liquid film M. A nozzle plate, wherein L2/L1 is set to 0.01 or more and 0.1 or less, where L2 is the depth of the liquid holding portion. The recessed portion of the liquid holding portion includes a portion including the ejection port, and an annular recessed portion surrounding the portion including the ejection port and recessed beyond the portion including the ejection port. is the restricting portion. a portion including the ejection port protrudes from a position around the liquid holding portion;
3. A ratio of a/b is greater than 0 and equal to or less than 2, where a is a projection length of the portion including the ejection port with respect to the position around the liquid holding portion, and b is the diameter of the ejection port. Nozzle plate as described in . the part including the ejection port is at the same position as the periphery of the liquid holding part or recessed from the position around the liquid holding part;
wherein c/b is -1 or more and 0 or less, where c is the recessed length of the portion including the ejection port with respect to the position around the liquid holding portion, and b is the diameter of the ejection port. 2. The nozzle plate according to 2. A nozzle plate having, in a nozzle plate main body, a storage chamber in which liquid is stored, a discharge channel communicating with the storage chamber, and a discharge port provided at an end of the discharge channel for discharging the liquid. ,
a liquid holding part that holds a liquid film formed so as to cover the ejection port and is surrounded by a restricting part that restricts the spread of the liquid film, wherein the center of the liquid holding part has a shape when viewed from a plane; The circular discharge port is open,
S1/S2 is larger than 25 and smaller than 2500, where S1 is the area of the liquid holding portion and S2 is the area of the ejection port when viewed from the plane,
The thickness of the liquid film held in the liquid holding portion is five times or less than the diameter of the ejection port, and the amount (volume) of the liquid ejected per one time is C1, and the volume of the liquid film M is C2. When C2/C1 is set to 20 or more and 900 or less,
The nozzle plate, wherein the liquid retaining portion is a convex portion protruding from a position around the liquid retaining portion, and an end portion of the convex portion is the restricting portion. The liquid holding portion includes an annular projection protruding from a position around the liquid holding portion, and a portion including the ejection port projecting from the annular projection. 6. The nozzle plate according to claim 5, wherein: a water-repellent layer having holes for exposing the ejection ports on the lower surface of the nozzle plate body;
2. The nozzle plate according to claim 1 , wherein the inner surface of the hole of the water-repellent layer is at least part of the regulation portion of the liquid holding portion. A liquid ejection device that ejects a liquid by pressurizing the liquid,
A pressurizing part, and the nozzle plate according to any one of claims 1 to 7 provided at the lower end of the pressurizing part,
The pressure unit is
a pressurizing unit body;
a pressurizing member that is supported by the pressurizing unit main body so as to be freely movable in the vertical direction, has a lower end projecting from the pressurizing unit main body, and pressurizes the liquid introduced into the storage chamber to discharge it from the discharge channel;
and a drive unit that vertically moves the pressure member. A liquid ejection method for ejecting the liquid contained in the storage chamber from the ejection port using the nozzle plate according to any one of claims 1 to 7,
forming and holding a liquid film so as to cover the ejection port;
A step of ejecting a liquid mass composed of part of the liquid film and part of the liquid contained in the storage chamber as a droplet, wherein when the liquid mass separates from the liquid film, the liquid is discharged. ejecting, wherein the membrane remains covering the ejection port;
A liquid ejection method, comprising:

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