JP2007276256A - Liquid droplet discharging head, liquid droplet discharging device, and manufacturing method for liquid droplet discharging head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharging head which can make a contact angle of liquid droplets to the nozzle surface large even if a liquid droplet of any size comes into contact with the nozzle surface, and to provide a liquid droplet discharging device and a manufacturing method for the liquid droplet discharging head. <P>SOLUTION: The maximum radius of a circle which is inscribed in a recess section 50 is taken as Rmax, and the depth d of the recess section 50 is made larger than 2Rmax, i.e., the maximum inscribed circle diameter. Thus, even if a mist 100 has entered the recess section 50, a gap can be provided between the upper edge section of the recess section 50 and the mist 100 in the recess section 50. That is, even if an ink droplet of whichever size has adhered to the nozzle surface 56, an air layer 54 can be formed in the recess section 50, and a super-water repellence can be retained (a contact angle to the nozzle surface 56 can be made larger). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge apparatus such as an inkjet recording apparatus, a droplet discharge head, and a method for manufacturing a droplet discharge head.

  In a droplet discharge head that discharges droplets, a water repellent treatment is performed on the nozzle surface by dipping, spraying, CVD, etc. (here, water repellent includes liquids other than water). However, it is difficult to obtain super water repellency such that the contact angle of the droplet with the water repellent film exceeds 120 ° in the case of a water repellent film. There is a problem that the material enters the nozzle.

As a method for solving these problems, in Patent Document 1, irregularities are provided on the nozzle surface to physically cause water repellency. However, in order to obtain super water repellency, an air layer is held in the recess. It is necessary. Although the size of the droplets adhering to the nozzle surface varies, the recesses are only sized so that the droplets do not fall into the recesses. Considering a certain fine droplet (mist), the concave portion is filled with the fine droplet, and the super water repellency cannot be maintained.
JP 2000-203035 A

  In consideration of the above facts, the present invention provides a droplet discharge head, a droplet discharge device, and a droplet capable of increasing the contact angle of the droplet with respect to the nozzle surface no matter what size droplet contacts the nozzle surface. It aims at obtaining the manufacturing method of a discharge head.

  In order to achieve the above object, according to a first aspect of the present invention, in the droplet discharge head, a recess is provided on a nozzle surface on which a nozzle for discharging a droplet is formed, and the depth of the recess is reduced into the recess. It is characterized in that it is deeper than the maximum diameter of the sphere that can enter and the nozzle diameter is larger than the maximum diameter of the sphere.

  In the first aspect of the present invention, by providing the recess on the nozzle surface, an air layer can be formed between the droplet adhering to the nozzle surface and the recess. It can be enlarged (so-called super water repellency can be obtained).

  In addition, by setting the depth of the concave portion to be deeper than the maximum diameter of the sphere that can enter the concave portion, even if a micro droplet enters the concave portion, the upper edge portion (nozzle surface) of the concave portion and the liquid in the concave portion Since a gap can be provided between the droplets, an air layer can be secured between the droplets adhering to the nozzle surface and the recesses, and the contact angle can be maintained.

  That is, the contact angle with respect to the nozzle surface can be increased for any size droplet. In this case, it is not always necessary to provide the water repellent film on the nozzle surface, so that the number of manufacturing steps can be reduced and the cost can be increased.

  According to a second aspect of the present invention, in the droplet discharge head according to the first aspect, the wettability of the nozzle surface is increased by reducing the area of the concave portion per unit area in a direction away from the nozzle. It is characterized by that.

  In the second aspect of the invention, the area of the recess per unit area is reduced in the direction away from the nozzle, thereby reducing the capacity of the air layer and increasing the wettability of the nozzle surface (separate from the nozzle). As a result, the contact angle of the liquid droplet with the nozzle surface becomes smaller and the water repellency becomes lower. As a result, it is possible to easily move the droplets adhering to the vicinity of the nozzle in a direction away from the nozzle.

  According to a third aspect of the present invention, in the liquid droplet ejection head according to the second aspect, the cleaning device is provided with a cleaning member that slides on the nozzle surface and removes the liquid droplets attached to the nozzle surface. The area of the recess per unit area is reduced along the line.

  According to the third aspect of the present invention, by reducing the area of the recess per unit area along the cleaning direction of the cleaning member, the capacity of the air layer can be reduced and the wettability of the nozzle surface can be increased. As a result, the droplets adhering to the nozzle surface can easily move along the cleaning direction of the cleaning member, and the cleaning performance can be improved when the nozzle surface is cleaned by the cleaning member.

  According to a fourth aspect of the present invention, in the liquid droplet ejection head according to any one of the first to third aspects, a plurality of short unit heads each having the nozzle surface are joined together, and the unit heads are joined together. The concave portion is provided in the joint portion.

  In the case where a long head or a full line head is manufactured by connecting unit heads, if the nozzle surface is wiped (cleaned), droplets are likely to accumulate in a connecting portion where the unit heads are connected. For this reason, in invention of Claim 4, the recessed part is provided in the connection part and it is trying to obtain super water repellency in a connection part. Thereby, the cleaning performance of a joint part can be improved.

  Here, by reducing the area of the concave portion per unit area on the end side than the central part of the joint part, reducing the volume of the air layer and increasing the wettability of the nozzle surface, the liquid accumulated in the joint part Drops can be moved from the center of the splice to the end. For this reason, the cleaning performance of the joint portion can be further improved.

  According to a fifth aspect of the present invention, in the liquid droplet ejection head according to any one of the first to fourth aspects, a water repellent film is deposited on the surface of the nozzle surface.

  In the invention described in claim 5, a water repellent film may be formed on the surface of the nozzle surface, which increases the number of manufacturing steps, but can further improve the water repellency of the nozzle surface (nozzle The wettability of the surface is reduced, and the contact angle of the droplet with the nozzle surface is increased).

  According to a sixth aspect of the present invention, in the liquid droplet ejection head according to any one of the first to fifth aspects, a counterbore portion is formed at a peripheral edge portion of the nozzle.

  According to the sixth aspect of the present invention, the nozzle can be protected from wiping by the cleaning member, paper jam, and the like by forming a counterbore portion at the peripheral edge of the nozzle.

  According to a seventh aspect of the present invention, in the droplet discharge device, the droplet discharge head according to any one of the first to sixth aspects is provided.

  According to an eighth aspect of the present invention, in the method for manufacturing a droplet discharge head, the concave portion and the nozzle according to any one of the first to sixth aspects are formed by etching.

  In the invention according to claim 8, since the concave portion and the nozzle can be formed at a time, the number of manufacturing steps can be reduced.

  Since the present invention has the above-described configuration, the contact angle with respect to the nozzle surface can be increased for any size droplet.

  Hereinafter, an outline of an ink jet recording apparatus provided with a recording head nozzle as a droplet discharge head according to an embodiment of the present invention will be described with reference to FIG.

  The recording medium is a recording paper P, the conveyance direction of the recording paper P in the inkjet recording apparatus 70 is represented by an arrow S as a sub-scanning direction, and the direction perpendicular to the conveyance direction is represented by an arrow M as a main scanning direction.

  The ink jet recording apparatus 70 includes a carriage 76 on which black, yellow, magenta, and cyan ink jet recording units 72 are mounted. A pair of brackets 78 project from the carriage 76 on the upstream side in the conveyance direction of the recording paper P, and the bracket 78 has a circular opening 78A. A shaft 80 installed in the main scanning direction is inserted through the opening 78A.

  A driving pulley 84 and a driven pulley 86 constituting the main scanning mechanism 82 are disposed at both ends in the main scanning direction. A timing belt 88 is wound around the driving pulley 84 and the driven pulley 86. The timing belt 88 is fixed to a carriage 76, and the carriage 76 can reciprocate in the main scanning direction.

  In addition, the inkjet recording apparatus 70 is provided with a sub-scanning mechanism 94 including a transport roller 90 and a discharge roller 92, and one sheet from a paper feed tray 96 on which recording paper P before image printing is placed in a bundle. The recording sheets P fed one by one are conveyed in the sub-scanning direction at a predetermined pitch.

  Further, as shown in FIG. 2, each color ink jet recording unit 72 includes an ink jet recording head 74 and an ink tank 98 that supplies ink thereto, and is formed on the lower surface of the ink jet recording head 74. The plurality of nozzles 10 (see FIG. 3) thus mounted are mounted on the carriage 76 so as to face the recording paper P.

  Accordingly, the ink jet recording head 74 selectively ejects ink droplets from the nozzles 10 to the recording paper P while moving in the main scanning direction by the main scanning mechanism 82 (see FIG. 1), whereby a predetermined band region BE is obtained. In contrast, a part of the image based on the image data is recorded.

  When one movement in the main scanning direction is completed, the recording paper P is conveyed at a predetermined pitch in the sub scanning direction by the sub scanning mechanism 94 (see FIG. 1), and again the ink jet recording head 74 (ink jet recording unit 72). Is moving in the main scanning direction (the direction opposite to the above), and a part of the image based on the image data is recorded in the next band area, and this operation is repeated a plurality of times. Thus, the entire image based on the image data is recorded on the recording paper P in full color.

  Next, the ink jet recording head 74 will be described in detail.

  As shown in FIG. 4, the inkjet recording head 74 is provided with a common ink chamber 20 to which ink is supplied from an ink tank 98 (see FIG. 2). An opening 18 is provided in the common ink chamber 20, and the pressure chamber 14 communicates with the ink supply path 16 so that ink in the common ink chamber 20 is supplied.

  Further, the inkjet recording head 74 is provided with a plurality of nozzles 10 (see FIG. 3) arranged in a single row or in two or more rows in a staggered manner, and the pressure chambers 14 are connected via the nozzle communication chamber 12. Communicate. A vibration plate 30 having elasticity in the vertical direction is provided on the upper surface of the pressure chamber 14, and a piezoelectric element 42 is disposed on the upper surface of the vibration plate 30 corresponding to the pressure chamber 14.

  An electric substrate 36 is bonded onto the piezoelectric element 42 via a ball solder 34. When the piezoelectric element 42 is energized (when a voltage is applied), the piezoelectric element 42 is bent and deformed in the vertical direction. Accordingly, the vibration plate 30 is bent and deformed, and ink is ejected from the nozzle 10 when the ink in the pressure chamber 14 is pressurized.

  By the way, in this embodiment, as shown in FIGS. 4 to 6, the nozzle surface 56 of the nozzle plate 21 is provided with the concave portions 50 (where the convex portions formed by the concave portions 50 are formed in a lattice shape with a width smaller than the nozzle diameter). Hereinafter, it is referred to as a convex portion 52, and the top surface of the convex portion 52 is a nozzle surface 56) (here, the peripheral portion of the nozzle 10 is an annular convex portion 52). Therefore, in the vicinity of the nozzle 10, the pitch of the convex portions 52 is not uniform depending on the angle with respect to the arrangement direction of the nozzles 10). And when the air layer 54 is formed in the recessed part 50 and ink larger than the recessed part 50 adheres to the nozzle surface 56, what is called a super-water-repellent property (this water-repellent also includes liquids other than water) arises. .

When the contact angle of the ink on the non-concave surface as shown in FIG. 7A is θ, the contact angle on the uneven surface including the air layer 54 is θ ′ larger than θ as shown in FIG. 7B. Thus, the apparent contact angle when the air layer is trapped in the concave portion is obtained by setting component 2 as air (θ ₂ = 180 °) in the following Cassie equation.

cos θ ′ = Q ₁ cos θ ₁ + Q ₂ cos θ ₂ (Formula 1)
Here, Q ₁ and Q ₂ are the ratios of the components 1 and 2 occupying the surface, and θ ₁ and θ ₂ are the true contact angles of the components 1 and 2. That is, it is shown that the contact angle becomes a higher value by trapping the air layer in the rough concave portion on the hydrophobic surface. That is, even if the material has high wettability (small contact angle), the contact angle can be increased (super water repellency can be obtained) by providing the air layer.

Further, in the present invention, as shown in FIGS. 8A and 8B, the depth d of the recess 50 is made deeper than the maximum diameter 2Rmax of the ink droplet that can enter the recess 50. Yes. That means
2Rmax <d (Formula 2)
The recess 50 is formed under the conditions.

  FIG. 9 shows the relationship between the amount of ejected ink and the diameter of the formed (spherical) ink droplet. In a normal printer, the amount of ink droplets ejected from the nozzle is about 1 to 20 pl, and the ink droplet diameter is 12 to 33 μm. When an ink droplet is ejected from a nozzle, it is known that the ink droplet is separated into a relatively large droplet called a main droplet and a small droplet called a satellite. The size is preferably 10 μm or less.

  In addition, when the main droplet size is 28 μm, satellites have been reported in the literature as 12 μm and mist size as 6 μm (reference: N. Hirooka, PIV Measurements of Airflow and Ink Mist Motion around Ink Jet Nozzles, 2003 International Conference). on Digital Printing Technologies), satellites and mists are even smaller when the main drops are small.

  From the above, in the present invention in which the diameter of the nozzle 10 is 25 μm, 2Rmax is set to 5.7 μm and d is set to 7 μm.

  Then, as shown in FIG. 13 (A), the width of the recess 50 is gradually reduced (the pitch of the protrusions 52 is gradually increased) in the direction away from the nozzle 10, and the recess 50 per unit area is reduced. The area is made small.

Here, the ink composition of this embodiment is
-Mogul L (manufactured by Cabot) (pigment / no surface functional group): 4 wt%
-Styrene-acrylic acid-sodium acrylate copolymer: 0.6 wt%
・ Diethylene glycol: 15wt%
・ Diglycerin ethylene oxide adduct: 5 wt%
・ Polyoxyethylene-2-ethylhexyl ether: 0.75 wt%
-Ion-exchanged water: remainder The ink has a surface tension of 32 mN / m and a viscosity of 3.3 mPa · s.

  Next, a method for forming the nozzle plate 21 will be described.

As shown in FIG. 10A, first, a pattern corresponding to the concavo-convex portion is formed with the SiO ₂ film 60 on the silicon substrate 58 corresponding to the nozzle plate 21. Next, as shown in FIG. 10 (B), a resist 64 is formed on the SiO ₂ film 60 in order to protect the concavo-convex portion when the nozzle 10 is formed.

  Then, as shown in FIG. 10C, the nozzle 10 is recessed by RIE (Reactive Ion Etching) (in this step, the silicon substrate 58 is penetrated to form the nozzle 10. Is also good).

Next, as shown in FIG. 10D, after removing the resist 64, as shown in FIG. 10E, the recess 50 is formed by RIE, and the nozzle 10 is formed through the silicon substrate 58. To do. Then, as shown in FIG. 10F, the SiO ₂ film 60 is removed.

  Through the steps as described above, the recess 50 is formed in the nozzle surface 56 of the nozzle plate 21. Here, since the recess 50 and the nozzle 10 are formed at a time, the number of manufacturing steps can be reduced.

  In the nozzle plate 21 formed as described above, the contact angle of the ink droplet with respect to the nozzle surface 56 is 120 ° (about 50 ° on Si having an oxidized surface).

  Further, as shown in FIG. 11A, a pattern corresponding to the unevenness may be formed with the SiO 2 film 60 on the polyimide film 66 in addition to the silicon substrate 58.

  In this case, as shown in FIG. 11B, the recess 50 is formed by RIE, and the nozzle 10 is provided by the depth of the recess 50 (in this step, the polyimide film 66 is penetrated to form the nozzle 10 may be formed).

  Next, as shown in FIG. 11C, the SiO 2 film 60 is peeled off. Then, as shown in FIG. 11D, the back side of the polyimide film 66 is irradiated by an excimer laser (not shown) through a mask 68 in which a hole 68A corresponding to the nozzle 10 is formed. Thereby, the nozzle 10 is formed.

  In the nozzle plate 21 formed as described above, the contact angle of the ink droplet with respect to the nozzle surface 56 is 100 ° (about 30 ° on the polyimide surface).

  In addition, although not shown in the drawings, the resin film may be formed with a recess by nanoimprinting, or may be formed with a metal plate such as Ni by electroforming.

  Next, the operation of the ink jet recording head 74 according to the embodiment of the present invention will be described.

  As shown in FIGS. 8A and 8B, the mist 100 has entered the recess 50 by making the depth d of the recess 50 deeper than the maximum diameter 2Rmax of the mist 100 that can enter the recess 50. However, a gap can be provided between the upper edge (nozzle surface 56) of the recess 50 and the mist 100 in the recess 50.

  That is, even if an ink droplet of any size adheres to the nozzle surface 56, the air layer 54 can be formed in the recess 50, so that super water repellency can be maintained (the contact angle with respect to the nozzle surface 56 is reduced). Can be larger).

  Further, since the super water repellency can be maintained in this way, it is not always necessary to provide the water repellent film on the nozzle surface 56. When the water repellent film is not provided on the nozzle surface 56, the number of manufacturing steps can be reduced and the cost can be increased.

  However, in the present invention, since a higher water repellency can be obtained by applying a water repellent film to the nozzle surface 56, it is not denied that the water repellent film is applied to the nozzle surface 56. As shown in FIGS. 12A and 12B, when a water repellent film 57 is applied to the nozzle surface 56, a counterbore portion 102 is provided in the peripheral portion of the nozzle 10, and wiping is performed by a cleaning blade 104 (described later). Alternatively, the nozzle 10 may be protected from paper jam or the like.

  By the way, in this embodiment, as shown in FIG. 13A, the width of the recess 50 is reduced in the direction away from the nozzle 10 so that the area of the recess 50 per unit area is reduced. As a result, the capacity of the air layer 54 is reduced in the direction away from the nozzle 10 to increase the wettability (water repellency is reduced).

  That is, as shown in FIG. 3, the nozzle surface 56 of the ink jet recording head 74 has a distribution of water repellency, the super water-repellent region 106 is provided in the vicinity of the nozzle 10, and the water repellency is provided on the peripheral side of the nozzle plate 21. By providing the water repellency reduction region 108 with reduced water, the ink adhered to the nozzle surface 56 moves in a direction away from the nozzle 10.

  Here, as shown in FIG. 13A, the width of the recess 50 is reduced in the direction away from the nozzle 10 so that the area of the recess 50 per unit area is reduced. Since it is sufficient that the area of the recess 50 can be reduced in the direction away from the center, the present invention is not limited to this.

  For example, as shown in FIG. 13B, the area of the convex portion 52 per unit area may be increased and the area of the concave portion 50 may be decreased in the direction away from the nozzle 10. In addition, since it is sufficient that the nozzle surface 56 has a distribution of water repellency, the width of the recess 50 does not necessarily have to be gradually changed in the super water-repellent region 106. This is the same in the following.

  When cleaning the nozzle surface 56, as shown in FIG. 14, when wiping ink droplets attached to the nozzle surface 56 by the cleaning blade 104, the unit along the wiping direction (arrow direction) of the cleaning blade 104 is used. The area of the recess 50 per area is reduced to increase the wettability of the nozzle surface 56.

  As a result, the ink droplets adhering to the nozzle surface 56 can be easily moved along the wiping direction of the cleaning blade 104, and the cleaning performance can be improved when the nozzle surface 56 is wiped by the cleaning blade 104. .

  On the other hand, in FIG. 15, the long head 112 is formed by connecting the inkjet recording heads 74 (unit heads) formed in a substantially trapezoidal shape. In the long head 112, the inkjet recording heads 74 are arranged in a staggered pattern on the substrate 113 so that the pitches of the nozzles 10 along the longitudinal direction are the same.

  The connecting portion 114 that connects the ink jet recording heads 74 is provided with a recess 50 so that the water repellency of the nozzle surface 56 is increased. On the other hand, the boundary between the substrate 113 and the side end portion of the ink jet recording head 74 has high wettability (low water repellency).

  In other words, the water repellency is distributed at the boundary between the substrate 113 and the ink jet recording head 74, the connecting portion 114 connecting the ink jet recording heads 74 is the super water repellent region 106, and the side end of the ink jet recording head 74 is the water repellent portion. A lowered region 108 is set.

  When a long or full line head is manufactured by connecting the inkjet recording head 74, ink droplets are likely to accumulate in the connecting portion 114 when the nozzle surface 56 is wiped. For this reason, the joining portion 114 of the ink jet recording head 74 is used as the super water-repellent region 106, and the boundary between the substrate 113 and the side end portion of the ink jet recording head 74 is used as the water repellent reduction region 108. Ink droplets are moved onto the substrate 113. Thereby, the cleaning performance of the connection part 114 can be improved.

  In the connecting portion 114, the ink accumulated in the connecting portion 114 is connected by decreasing the area of the concave portion 50 per unit area from the center portion to the end portion to increase the wettability of the nozzle surface 56. It can be made easy to move from the center part of the part 114 to an edge part. Thereby, the cleaning performance of the connection part 114 can further be improved.

  Here, although not shown, in addition to wiping by the cleaning blade 104, an air compressor or the like is provided so that air is blown onto the nozzle surface 56, whereby the ink adhering to the nozzle surface 56 is separated from the nozzle 10. And the ink on the nozzle surface 56 can be efficiently removed. Thus, by reliably removing the ink adhering to the nozzle surface 56, it is effective to maintain the water repellency of the nozzle surface 56.

  Here, the case where the nozzles 10 are arranged in one row or in two or more rows in a zigzag manner has been described. However, as shown in FIGS. 16A and 16B, the nozzles 10 are arranged in a matrix. The inkjet recording head 116 thus formed is the same as the inkjet recording head 74 shown in FIG. That is, the super water-repellent region 106 is provided in the vicinity of the nozzle 10, and the water-repellent reduction region 108 is provided on the peripheral side of the nozzle plate 118.

  In addition, here, the lattice-shaped recesses 50 having a width smaller than the nozzle diameter are formed on the nozzle surface 56 of the nozzle plate 21, but it is only necessary that the recesses can be formed on the nozzle surface 56. . For example, a plurality of prismatic or cylindrical recesses may be provided.

  Further, in the ink jet recording apparatus 70 of the above embodiment, black, yellow, magenta, and cyan ink jet recording units 72 are mounted on the carriage 76, and the ink jet recording heads 74 of these colors are selectively selected based on image data. Although ink droplets are ejected and a full-color image is recorded on the recording paper P, ink jet recording in the present invention is not limited to recording characters and images on the recording paper P.

  That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrially used liquids such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging welded solder onto a substrate The ink jet recording head 74 according to the present invention can be applied to all droplet ejecting apparatuses.

  Further, in the ink jet recording apparatus 70 of the above embodiment, the example of the partial width array (PWA) having the main scanning mechanism 82 and the sub scanning mechanism 94 has been described. However, the ink jet recording in the present invention is not limited to this, and the paper width A corresponding so-called Full Width Array (FWA) may be used.

1 is a perspective view showing an ink jet recording apparatus to which an ink jet recording head according to an embodiment of the present invention is applied. 1 is a perspective view showing an ink jet recording unit to which an ink jet recording head according to an embodiment of the present invention is applied. It is a bottom view showing an ink jet recording head of an embodiment of the present invention. 1 is a cross-sectional view illustrating an ink jet recording head according to an embodiment of the present invention. FIG. 2A is a cross-sectional view illustrating a nozzle plate of an ink jet recording head according to an embodiment of the present invention, and FIG. It is a perspective view which shows the nozzle surface of the inkjet recording head which concerns on embodiment of this invention. (A) is explanatory drawing explaining the contact angle of the droplet in a smooth surface, (B) is explanatory drawing explaining the contact angle of the droplet in the uneven surface containing an air layer. FIG. 2A is a bottom view and FIG. 2B is a cross-sectional view illustrating a nozzle surface of an ink jet recording head according to an embodiment of the present invention. It is a graph which shows the relationship between the amount of ejected inks, and the diameter of the ink droplet formed. (A)-(F) are sectional drawings which show the manufacturing process of the nozzle plate of the inkjet recording head which concerns on embodiment of this invention. (A)-(D) are sectional drawings which show the other manufacturing process of the nozzle plate of the inkjet recording head which concerns on embodiment of this invention. The modification of the nozzle plate of the inkjet recording head which concerns on embodiment of this invention is shown, (A) is sectional drawing, (B) is a bottom view. (A) is a bottom view showing the nozzle plate of the ink jet recording head according to the embodiment of the present invention, and (B) is a modification. It is explanatory drawing explaining the relationship between the recessed part of the nozzle surface of the inkjet recording head which concerns on embodiment of this invention, and the wiping of a cleaning blade. It is the long head which connected the inkjet recording head which concerns on embodiment of this invention. (A), (B) is explanatory drawing showing the state by which the nozzle of the inkjet recording head which concerns on embodiment of this invention was arrange | positioned at matrix form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nozzle 50 Concave part 52 Convex part 54 Air layer 56 Nozzle surface 57 Water-repellent film 70 Inkjet recording apparatus (droplet discharge apparatus)
72 Inkjet recording unit 74 Inkjet recording head (droplet ejection head)
DESCRIPTION OF SYMBOLS 100 Mist 102 Counterbore part 104 Cleaning blade 106 Super water-repellent area 108 Water-repellent fall area 112 Long head 114 Joint part 116 Inkjet recording head

Claims (8)

  A recess is provided on the nozzle surface on which the nozzle for discharging droplets is formed, the depth of the recess is made deeper than the maximum diameter of the sphere that can enter the recess, and the nozzle diameter is made larger than the maximum diameter of the sphere. A droplet discharge head characterized by the above.   2. The droplet discharge head according to claim 1, wherein the wettability of the nozzle surface is increased by decreasing the area of the concave portion per unit area in a direction away from the nozzle. A cleaning member that slides on the nozzle surface and removes droplets attached to the nozzle surface,
The droplet discharge head according to claim 2, wherein an area of the concave portion per unit area is reduced along a cleaning direction of the cleaning member. A plurality of short unit heads provided with the nozzle surface are connected,
The liquid droplet ejection head according to claim 1, wherein the concave portion is provided in a joint portion where the unit heads are joined together.   The liquid droplet ejection head according to claim 1, wherein a water repellent film is deposited on the surface of the nozzle surface.   The droplet discharge head according to any one of claims 1 to 5, wherein a counterbore portion is formed at a peripheral portion of the nozzle.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1.   A method for manufacturing a droplet discharge head, wherein the recess and the nozzle according to any one of claims 1 to 6 are formed by etching.