JP2008213421A - Nozzle plate manufacturing method, nozzle plate, liquid discharge head, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle plate in which highly precise constricted nozzles are formed. <P>SOLUTION: The manufacturing method includes the process of forming a tapered hole part 51a which becomes gradually narrow from a first principal plane of a single crystal silicon substrate 62 towards a second principal plane by anisotropically etching the single crystal silicon substrate, the process of forming a resist to at least the second principal plane side of the single crystal silicon substrate, the process of exposing the resist in a reverse tapered shape which becomes gradually wide towards a direction of the second principal plane from the first principal plane by making the single crystal substrate formed with the tapered hole part a mask, the process of developing the resist, the process of forming a functional membrane 64 to the second principal plane side of the single crystal silicon substrate, and the process of removing the resist. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nozzle plate manufacturing method, a nozzle plate, a liquid discharge head, and an image forming apparatus, and in particular, a tapered hole portion that gradually narrows toward the liquid discharge side, and the taper hole portion toward the liquid discharge side. The present invention relates to a manufacturing technique of a nozzle plate in which a constricted nozzle composed of an inversely tapered hole portion that is gradually widened.

  In general, a recording head of an ink jet recording apparatus is provided with a nozzle plate in which a plurality of nozzles are formed, and recording is performed by ejecting ink droplets from each nozzle toward a recording medium. For example, there are recording heads such as a piezoelectric system that ejects ink using displacement of a piezoelectric element, and a thermal system that ejects ink using thermal energy generated by a heating element.

  In order to realize high image quality and high-speed recording in such an ink jet recording apparatus, it is required to increase the accuracy and increase the number of nozzles formed on the nozzle plate. In particular, in order to enable high-speed ejection of high-viscosity ink, it is necessary to lower fluid resistance and improve ink refilling properties, and a tapered nozzle that gradually narrows toward the ink ejection side is required.

  However, in such a tapered nozzle, the ink discharge side opening edge (nozzle edge) has an acutely sharp shape, so that the nozzle plate surface (ink discharge surface) is formed with a blade made of rubber or the like, for example. If wiping is performed, the blade may hit the nozzle edge portion and the nozzle edge portion may be damaged. In addition, the tapered nozzle has a problem that the opening diameter on the side opposite to the ink discharge side (ink inflow side) is large, and is not suitable for increasing the number of nozzles.

  In order to deal with such a problem, for example, in Patent Document 1, a silicon substrate (silicon wafer) in which the (100) plane of a silicon single crystal is oriented on the surface is anisotropically etched from both sides, and the minimum diameter portion of the nozzle There has been proposed a nozzle plate in which is provided in the middle part of the thickness of the silicon substrate.

  Many nozzle plates have a liquid repellent film (ink repellent film) on the surface on the ink ejection side. In the ink jet recording method, fine ink droplets (satellite droplets) are easily generated at the same time as ink droplets are ejected from each nozzle, and the fine ink droplets may adhere to the surface of the nozzle plate. In particular, when fine droplets adhere to the periphery of the nozzle opening, variations occur in the flying direction of the ink droplets, and the landing positions of the ink droplets are shifted, causing image defects such as uneven density and white stripes. For this reason, a liquid repellent film is provided on the surface of the nozzle plate so that the fine droplets adhering to the nozzle plate surface can be easily removed by wiping.

  However, if the edge part (near the edge of the opening part edge) in the liquid repellent film is formed with an acute angle as in the case of the wide-angle taper nozzle, there is a problem that the liquid repellent film is peeled off by wiping. is there. In addition, there is a possibility that the ink ejection stability (ejection stability) may vary.

To deal with such a problem, for example, in Patent Document 2, the shape of the opening of the liquid repellent film formed on the surface of the nozzle plate is a round shape in which the opening area gradually increases toward the ink ejection side. A nozzle plate configured as described above has been proposed.
JP 56-126460 A JP 2006-51808 A

  In general, according to a technique for anisotropically etching a silicon substrate (silicon wafer), a tapered nozzle having an inclined surface (tapered surface) inclined obliquely with respect to the surface to be etched can be formed. Since the tilt angle (taper angle) is determined by the silicon crystal plane, a uniform and accurate nozzle can be obtained.

  However, in Patent Document 1, the constricted nozzle is formed by anisotropic etching from both sides of the silicon substrate, and the position is determined by the hole etched from one surface and the hole etched from the other surface. Misalignment is likely to occur, and the central axis (nozzle axis) of the constricted nozzle constituted by these two holes may be misaligned. For this reason, there is a possibility that adverse effects such as variations in the flying direction of the ink droplets ejected from the nozzles may occur. Further, according to the same document, it is desirable that two through holes for positioning are previously formed in the silicon substrate in order to accurately match the coaxiality of the front and back patterns of the silicon substrate. There is no change in performing anisotropic etching on both surfaces in separate steps, and misalignment may occur due to an alignment error.

  Further, Patent Document 2 describes a method of forming a liquid repellent film (ink repellent film) by applying a silicone resin to the nozzle plate surface using a dispenser. However, with this alone, the nozzle is clogged with the silicone resin. There is a problem that causes it. Also, a mode in which silicon resin is applied while jetting gas from the nozzle, and a mode in which silicon resin is applied without jetting gas and the silicon resin intrudes to a predetermined depth and then jets gas from the nozzle are described. However, although it is considered that the clogging of the nozzle can be prevented in any of the embodiments, the round shape of the opening portion of the liquid repellent film is naturally formed, and thus there is a problem that the shape is likely to vary. There is also a problem that the change in angle at the point where the nozzle plate and the liquid repellent film are in contact is small, and the position of the meniscus is not stable.

  SUMMARY An advantage of some aspects of the invention is that it provides a nozzle plate manufacturing method, a nozzle plate, a liquid discharge head, and an image forming apparatus in which high-precision constricted nozzles are formed. .

  In order to achieve the above object, according to the first aspect of the present invention, the single crystal silicon substrate is anisotropically etched to become gradually narrower from the first main surface to the second main surface of the single crystal silicon substrate. The step of forming a tapered hole, the step of forming a resist on at least the second main surface side of the single crystal silicon substrate, and the single crystal silicon substrate in which the tapered hole is formed as a mask, Exposing the resist in a reverse taper shape gradually widening from the first main surface toward the second main surface; developing the resist; and the second main surface side of the single crystal silicon substrate And a step of forming a functional film, and a step of removing the resist.

  According to the present invention, the resist (photosensitive resin) formed on the second main surface side of the single crystal silicon substrate is reversely tapered using the single crystal silicon substrate in which the tapered hole is formed by anisotropic etching as a mask. By exposing to a high-precision resist pillar without a positional deviation with respect to the tapered hole portion of the single crystal silicon substrate after development, it has a reverse tapered hole portion corresponding to the outer shape of the resist column. The functional film can be formed on the second main surface side of the single crystal silicon substrate. As a result, a highly accurate constricted nozzle composed of a tapered hole portion and a reverse tapered hole portion can be collectively formed.

  Invention of Claim 2 is a manufacturing method of the nozzle plate of Claim 1, Comprising: The said 1st main surface of the said single crystal silicon substrate is comprised by the crystal plane orientation (100) plane It is characterized by.

  In the present invention, an embodiment in which the first main surface of the single crystal silicon substrate is constituted by a crystal plane orientation (100) plane is preferable. By performing anisotropic etching on the crystal plane orientation (100) plane, a highly symmetric nozzle can be formed, and the ejection direction can be stabilized.

  Invention of Claim 3 is a manufacturing method of the nozzle plate of Claim 1 or Claim 2, Comprising: The said resist is exposed using the light reflected on the surface exposed by the said anisotropic etching It is characterized by doing.

  In the present invention, a mode in which the resist is exposed by utilizing light reflected on the surface that appears by anisotropic etching (that is, the inner wall surface of the tapered hole portion formed in the single crystal silicon substrate) is preferable. Compared to the case where reflected light is not used, a reverse-angle resist pillar having a wide angle can be obtained, and the degree of freedom in the shape of the inverse-taper hole of the functional film formed corresponding to the outer shape of the resist pillar is improved. . In addition, by forming a wide-angle reverse-tapered hole in the functional film, the protection effect of the nozzle edge (nozzle edge on the liquid discharge side of the nozzle) is enhanced, and damage to the nozzle edge due to wiping is prevented. And the discharge stability is improved.

  Invention of Claim 4 is a manufacturing method of the nozzle plate of any one of Claim 1 thru | or 3, Comprising: A light-transmitting board | substrate at the said 1st main surface side of the said single crystal silicon substrate And exposing the resist through the light transmissive substrate.

  According to the aspect of claim 4, since the incident light to the resist is stabilized, a resist pattern (resist pillar) having a good shape accuracy can be obtained.

  Invention of Claim 5 is a manufacturing method of the nozzle plate of any one of Claim 1 thru | or 4, Comprising: The said functional film is a resin film or a metal film, It is characterized by the above-mentioned. To do.

  According to the aspect of the fifth aspect, the strength of the nozzle edge portion (liquid discharge side opening edge portion) is improved, and damage to the nozzle edge portion due to wiping or the like can be prevented.

  The invention according to claim 6 is the method for manufacturing a nozzle plate according to any one of claims 1 to 5, wherein the functional film is a film having liquid repellency with respect to ink. It is characterized by being.

  According to the aspect of the sixth aspect, it becomes easy to remove the droplets adhering to the nozzle plate by wiping or the like, and the positional stability of the meniscus is improved.

  The invention according to claim 7 is the method for manufacturing the nozzle plate according to claim 6, wherein the functional film is formed by eutectoid plating containing a fluororesin.

  According to the aspect of claim 7, the liquid repellent film can be formed with high accuracy, and since it is made of metal, the rigidity is high, and the effect of protecting the nozzle edge portion (liquid discharge side opening edge portion) is high. Damage to the nozzle edge due to wiping or the like can be prevented. In addition, the positional stability of the meniscus is improved.

  The invention according to claim 8 is the method of manufacturing a nozzle plate according to any one of claims 1 to 7, wherein the single crystal silicon substrate is anisotropically etched and then the single crystal silicon is formed. The method further includes the step of forming a metal film on the surface of the second main surface of the substrate, wherein the functional film is formed on the surface of the metal film after the exposure and development.

  According to the aspect of claim 8, by forming a metal film on the surface of the second main surface of the single crystal silicon substrate, it is possible to form a functional film by electroplating using the metal film as an electrode, The plating time can be shortened. It is also possible to form a functional film by electroless plating using a metal film as a base, and in this case, a catalytic step is not necessary.

  In order to achieve the above object, the invention according to claim 9 includes a tapered hole portion that gradually narrows toward the liquid discharge side, and a reverse that gradually widens from the tapered hole portion toward the liquid discharge side. A nozzle plate in which a constricted nozzle composed of a tapered hole is formed, wherein the tapered hole is formed in a single crystal silicon substrate, and the reverse tapered hole is the single crystal silicon. A nozzle plate is provided which is formed on a functional film disposed on a liquid discharge side of a substrate, and the functional film is made of a material different from that of the single crystal silicon substrate.

  According to the present invention, the flow path resistance is reduced by the tapered hole portion formed in the single crystal silicon substrate, and the nozzle edge portion (the liquid discharge side opening portion of the nozzle is formed by the reverse tapered hole portion formed in the functional film. ) Can be protected. Further, the meniscus position stability is increased at the interface between the tapered hole portion and the reverse tapered hole portion.

  A tenth aspect of the invention is the nozzle plate according to the ninth aspect of the invention, wherein the nozzle plate is formed in the opening on the liquid discharge side of the tapered hole portion formed in the single crystal silicon substrate and in the functional film. The opening on the opposite side to the liquid discharge side of the reverse tapered hole portion has the same shape.

  Invention of Claim 11 is the nozzle plate of Claim 9 or Claim 10, Comprising: The surface on the opposite side to the liquid discharge side of the said single crystal silicon substrate is comprised by the crystal plane orientation (100) plane. In addition, the inner wall surface of the tapered hole portion is formed of a crystal plane orientation (111) plane.

  A twelfth aspect of the invention is the nozzle plate according to any one of the ninth to eleventh aspects, wherein the inner wall surface of the reverse tapered hole portion formed in the functional film is relative to the nozzle shaft. The inclination angle is wider than the inclination angle of the inner wall surface of the tapered hole formed in the single crystal silicon substrate with respect to the nozzle axis.

  According to the aspect of claim 12, the position of the meniscus can be further stabilized, and the discharge stability is improved.

  A thirteenth aspect of the present invention provides a liquid discharge head comprising the nozzle plate according to any one of the ninth to twelfth aspects.

  According to the present invention, it is possible to realize a head having high durability and excellent discharge performance.

  According to a fourteenth aspect of the present invention, there is provided an image forming apparatus comprising the liquid discharge head according to the thirteenth aspect.

  According to the present invention, the resist (photosensitive resin) formed on the second main surface side of the single crystal silicon substrate is reversely tapered using the single crystal silicon substrate in which the tapered hole is formed by anisotropic etching as a mask. By exposing to a high-precision resist pillar without a positional deviation with respect to the tapered hole portion of the single crystal silicon substrate after development, it has a reverse tapered hole portion corresponding to the outer shape of the resist column. The functional film can be formed on the second main surface side of the single crystal silicon substrate. As a result, a highly accurate constricted nozzle composed of a tapered hole portion and a reverse tapered hole portion can be collectively formed.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Inkjet recording device]
First, an ink jet recording apparatus which is an embodiment of an image forming apparatus according to the present invention will be described. FIG. 1 is an overall configuration diagram showing an outline of an ink jet recording apparatus. As shown in FIG. 1, the inkjet recording apparatus 10 includes a printing unit 12 having a plurality of recording heads 12K, 12C, 12M, and 12Y provided for each ink color, and each recording head 12K, 12C, 12M, and 12Y. An ink storage / loading unit 14 for storing ink to be supplied to the printer, a paper supply unit 18 for supplying the recording paper 16, a decurling unit 20 for removing curling of the recording paper 16, and ink ejection of the printing unit 12 A suction belt conveying unit 22 that conveys the recording paper 16 while maintaining the flatness of the recording paper 16, a print detection unit 24 that reads a printing result by the printing unit 12, and a print And a paper discharge unit 26 for discharging the printed recording paper (printed matter) to the outside.

  In FIG. 1, a magazine for rolled paper (continuous paper) is shown as an example of the paper supply unit 18, but a plurality of magazines having different paper widths, paper quality, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  In the case of an apparatus configuration using roll paper, a cutter 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. The cutter 28 includes a fixed blade 28A having a length equal to or greater than the conveyance path width of the recording paper 16, and a round blade 28B that moves along the fixed blade 28A. The fixed blade 28A is provided on the back side of the print. The round blade 28B is arranged on the print surface side with the conveyance path interposed therebetween. Note that the cutter 28 is not necessary when cut paper is used.

  When multiple types of recording paper are used, an information recording body such as a barcode or wireless tag that records paper type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Therefore, it is preferable to automatically determine the type of paper to be used and perform ink ejection control so as to realize appropriate ink ejection according to the type of paper.

  The recording paper 16 delivered from the paper supply unit 18 retains curl due to having been loaded in the magazine. In order to remove this curl, heat is applied to the recording paper 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  After the decurling process, the cut recording paper 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least a portion facing the ink ejection surface of the printing unit 12 and the sensor surface of the printing detection unit 24 is flat. It is comprised so that it may make.

  The belt 33 has a width that is greater than the width of the recording paper 16, and a plurality of suction holes (not shown) are formed on the belt surface. As shown in FIG. 1, an adsorption chamber 34 is provided at a position facing the ink ejection surface of the printing unit 12 and the sensor surface of the printing detection unit 24 inside the belt 33 spanned between the rollers 31 and 32. The suction chamber 34 is sucked by the fan 35 to be a negative pressure so that the recording paper 16 on the belt 33 is sucked and held.

  The power of a motor (not shown) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, so that the belt 33 is driven in the clockwise direction in FIG. The recording paper 16 is conveyed from left to right in FIG.

  Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blowing method of spraying clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the print area, the roller contacts the print surface of the paper immediately after printing, so that the image blurs. There is a problem that it is easy. Therefore, as in this example, suction belt conveyance that does not contact the image surface in the printing region is preferable.

  A heating fan 40 is provided on the upstream side of the printing unit 12 on the paper conveyance path formed by the suction belt conveyance unit 22. The heating fan 40 heats the recording paper 16 by blowing heated air onto the recording paper 16 before printing. Heating the recording paper 16 immediately before printing makes it easier for the ink to dry after landing.

  The printing unit 12 is a so-called full-line type head in which line-type heads having a length corresponding to the maximum paper width are arranged in a direction (main scanning direction) orthogonal to the paper transport direction (sub-scanning direction). Each of the recording heads 12K, 12C, 12M, and 12Y constituting the printing unit 12 has a plurality of ink discharge ports (nozzles) arranged over a length exceeding at least one side of the maximum size recording paper 16 targeted by the inkjet recording apparatus 10. It is comprised by the made line type head (refer FIG. 2).

  Recording corresponding to each color ink in the order of black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side (left side in FIG. 1) along the conveyance direction (paper conveyance direction) of the recording paper 16. Heads 12K, 12C, 12M, and 12Y are arranged. A color image can be formed on the recording paper 16 by discharging the color inks from the recording heads 12K, 12C, 12M, and 12Y while conveying the recording paper 16.

  Thus, according to the printing unit 12 in which the full line head that covers the entire width of the paper is provided for each ink color, the recording paper 16 and the printing unit 12 are relatively moved in the paper transport direction (sub-scanning direction). It is possible to record an image on the entire surface of the recording paper 16 by performing this operation only once (that is, by one sub-scan). Thereby, high-speed printing is possible and productivity can be improved as compared with the shuttle type head in which the recording head reciprocates in the direction (main scanning direction) orthogonal to the paper transport direction.

  In this example, the configuration of KCMY standard colors (four colors) is illustrated, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink and dark ink are added as necessary. May be. For example, it is possible to add a recording head that discharges light ink such as light cyan and light magenta.

  As shown in FIG. 1, the ink storage / loading unit 14 has tanks that store inks of colors corresponding to the recording heads 12K, 12C, 12M, and 12Y, and each tank has a pipeline that is not shown. Via the recording heads 12K, 12C, 12M, and 12Y. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means, etc.) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. is doing.

  The print detection unit 24 includes an image sensor (line sensor or the like) for imaging the droplet ejection result of the print unit 12, and means for checking nozzle clogging and other ejection defects from the droplet ejection image read by the image sensor. Function as.

The print detection unit 24 of this example is composed of a line sensor having a light receiving element array that is wider than at least the ink ejection width (image recording width) of each recording head 12K, 12C, 12M, 12Y. This line sensor is a photoelectric conversion element (pixel) provided with a red (R) color filter.
A color separation line CCD sensor comprising: an R sensor array in which G is arranged in a line, a G sensor array provided with a green (G) color filter, and a B sensor array provided with a blue (B) color filter It consists of Instead of the line sensor, an area sensor in which the light receiving elements are two-dimensionally arranged can be used.

  The print detection unit 24 reads the test pattern printed by the recording heads 12K, 12C, 12M, and 12Y for each color, and detects the ejection of each head. The ejection determination includes the presence / absence of ejection, measurement of dot size, measurement of dot landing position, and the like.

  A post-drying unit 42 is provided following the print detection unit 24. The post-drying unit 42 is means for drying the printed image surface, and for example, a heating fan is used. Since it is preferable to avoid contact with the printing surface until the ink after printing is dried, a method of blowing hot air is preferred.

  When printing on porous paper with dye-based ink, the weather resistance of the image is improved by preventing contact with ozone or other things that cause dye molecules to break by blocking the paper holes by pressurization. There is an effect to.

  A heating / pressurizing unit 44 is provided following the post-drying unit 42. The heating / pressurizing unit 44 is a means for controlling the glossiness of the image surface, and pressurizes with a pressure roller 45 having a predetermined uneven surface shape while heating the image surface to transfer the uneven shape to the image surface. To do.

  The printed matter generated in this manner is outputted from the paper output unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. ing. Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by a cutter (second cutter) 48. The cutter 48 is provided immediately before the paper discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin. The structure of the cutter 48 is the same as that of the first cutter 28 described above, and includes a fixed blade 48A and a round blade 48B. Although not shown, the paper output unit 26A for the target prints is provided with a sorter for collecting prints according to print orders.

  Since the recording heads 12K, 12C, 12M, and 12Y provided for each ink color have the same structure, the recording head is represented by reference numeral 50 below.

[Recording head structure]
Next, the structure of the recording head 50 which is an embodiment of the droplet discharge head according to the present invention will be described.

  FIG. 3 is a perspective plan view showing an example of the structure of the recording head 50. As shown in FIG. 3, the recording head 50 of this example includes a plurality of ink chamber units (droplet discharge elements) including nozzles 51 serving as ink droplet discharge ports and pressure chambers 52 corresponding to the nozzles 51. 53 has a structure in which 53 are arranged in a staggered matrix (two-dimensional), so that the substantial nozzle interval projected so as to be aligned along the longitudinal direction of the recording head (direction perpendicular to the paper feed direction) High density (projection nozzle pitch) is achieved.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape, and nozzles 51 and supply ink inlets (supply ports) 54 are provided at both corners on the diagonal line. ing.

  The shape of the pressure chamber 52 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon and other polygons, a circle, and an ellipse. Further, the arrangement of the nozzles 51 and the supply ports 54 is not limited to the arrangement shown in FIG.

  4 is a cross-sectional view (a cross-sectional view taken along line 4-4 in FIG. 3) showing a three-dimensional configuration of one droplet discharge element (an ink chamber unit corresponding to one nozzle 51). FIG. 5 is an enlarged sectional view of the periphery of the nozzle 51.

  As shown in FIGS. 4 and 5, the nozzle plate 60 provided in the recording head 50 is disposed on the single crystal silicon substrate 62 and the second main surface 62 b side (ink ejection side) of the single crystal silicon substrate 62. It is comprised from the property film | membrane 64. FIG.

  The nozzle plate 60 includes a tapered hole 51a that gradually narrows toward the ink discharge side (the lower side in the drawing), and an inversely tapered hole 51b that gradually increases from the tapered hole 51a toward the ink discharge side. A constricted nozzle 51 is provided. The tapered hole 51 a is formed in the single crystal silicon substrate 62, and the reverse tapered hole 51 b is formed in the functional film 64. The first main surface 62a of the single crystal silicon substrate 62 is configured by a crystal plane orientation (100) plane, and the inner wall surface (inclined plane) 66 of the tapered hole 51a is configured by a crystal plane orientation (111) plane. .

  The functional film 64 is made of, for example, a metal film or a resin film, and is made of a material different from that of the single crystal silicon substrate 62. The functional film 64 is not limited to one layer, and two or more layers may be provided. The functional film 64 improves the strength of the ink ejection side opening edge (nozzle edge) of the nozzle 51, reduces stress concentration during wiping, and prevents damage to the nozzle edge. Thus, the functional film 64 also functions as a protective film for the nozzle 51. In particular, when the functional film 64 is made of a metal film, the rigidity is increased, so that the effect of nozzle protection is increased.

  In this specification, such a constricted nozzle is referred to as a “constricted nozzle”. Although not shown, a plurality of constricted nozzles 51 are two-dimensionally arranged on the nozzle plate 60 (see FIG. 3).

  As shown in FIG. 5, the constricted nozzle 51 in the present embodiment is manufactured by a manufacturing method in the case of using reflected light, which will be described later, and an inclination angle (taper angle) of the reverse tapered hole portion 51 b formed in the functional film 64. ) Θb is configured to have a wider angle (that is, θb> θa) than the inclination angle (taper angle) θa of the tapered hole 51 a formed in the single crystal silicon substrate 62. According to this configuration, it is possible to further stabilize the position of the meniscus. The inclination angles θa and θb are inclination angles with respect to the nozzle axis P of the corresponding inner wall surface of the hole.

  Further, the constricted nozzle 51 in the present embodiment is not shown, but the opening of the tapered hole 51a formed in the single crystal silicon substrate 62 and the reverse tapered hole 51b formed in the functional film 64 are omitted. The openings have the same shape. According to this configuration, the ejection stability is improved as compared with the case of different opening shapes.

  Each nozzle 51 formed in the nozzle plate 60 communicates with a corresponding pressure chamber 52 as shown in FIG. The pressure chamber 52 is a space filled with ink to be ejected from the nozzle 51, and a supply port 54 is formed at one end thereof, and communicates with the common flow channel 55 through the supply port 54. Although not shown, the common flow channel 55 communicates with the plurality of pressure chambers 52, and the ink supplied from the ink storage / loading unit 14 shown in FIG. To be distributed.

  The diaphragm 56 constitutes one wall surface (the upper surface in FIG. 4) of the pressure chamber 52 and is made of a conductive material such as stainless steel (SUS) or nickel (Ni), and is disposed corresponding to each pressure chamber 52. It also serves as a common electrode for the plurality of piezoelectric elements 58. It is also possible to form the diaphragm with a non-conductive material such as resin. In this case, a common electrode layer made of a conductive material such as metal is formed on the surface of the diaphragm member. Moreover, the aspect which forms a diaphragm with a silicon | silicone is also possible. On the surface opposite to the pressure chamber 52 side (the upper side in FIG. 4) on the diaphragm 56, a piezoelectric element 58 including individual electrodes 57 is provided at a position corresponding to each pressure chamber 52. A piezoelectric material such as lead zirconate titanate (PZT) is preferably used for the piezoelectric element 58.

  With this configuration, when a driving voltage is applied to the piezoelectric element 58, the volume of the pressure chamber 52 changes according to the deformation of the piezoelectric element 58, and the ink in the pressure chamber 52 is pressurized by the pressure change accompanying this, Ink droplets are ejected from a nozzle 51 communicating with the pressure chamber 52. When the application of the drive voltage is released after ink ejection, new ink is supplied from the common flow channel 55 through the supply port 54 to the pressure chamber 52.

  According to the present embodiment, the flow resistance of the tapered hole 51a in the constricted nozzle 51 is reduced, so that the refill property is improved, and high-frequency discharge of high-viscosity ink is possible. Further, the position stability of the meniscus is increased at the minimum diameter portion corresponding to the interface between the tapered hole portion 51a and the reverse tapered hole portion 51b, and the discharge stability is improved. Moreover, damage to the nozzle edge portion can be prevented by the functional film 64 in which the reverse tapered hole portion 51b is formed.

  Moreover, according to the aspect which provides the functional film 64 of two or more layers, the function with which the functional film 64 is provided can be changed for every layer, and various effects can be acquired.

  In the present embodiment, a method of ejecting ink droplets by deformation of the piezoelectric element 58 typified by a piezo element is employed. However, the present invention is not limited to a method of ejecting ink, and the piezo element is not limited. Instead of the method, a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure may be used.

[Configuration of ink supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. In the figure, an ink tank 80 is a base tank that supplies ink to the recording head 50, and is installed in the ink storage / loading unit 14 described in FIG. In the form of the ink tank 80, there are a system that replenishes ink from a replenishment port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink decreases. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type. The ink tank 80 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. 1 described above.

  A filter 82 is provided between the ink tank 80 and the recording head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter (generally about 20 μm). Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the recording head 50 or integrally with the recording head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the recording head 50.

  Further, the inkjet recording apparatus 10 is provided with a cap 84 as a means for preventing an increase in ink viscosity near the nozzles and drying, and a cleaning blade 86 as a means for cleaning the ink discharge surface 50a of the recording head 50. ing. The maintenance unit including the cap 84 and the cleaning blade 86 can be moved relative to the recording head 50 by a moving mechanism (not shown), and is moved from a predetermined retracted position to a maintenance position below the recording head 50 as necessary. The

  The cap 84 is displaced up and down relatively with respect to the recording head 50 by an elevator mechanism (not shown). The cap 84 is raised to a predetermined raised position when the power is turned off or during printing standby, and is brought into close contact with the recording head 50, thereby covering the ink ejection surface 50 a with the cap 84.

  The cleaning blade 86 is made of an elastic member such as rubber, and can slide on the ink discharge surface 50a of the recording head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matters adhere to the ink ejection surface 50a, the ink droplets or the like are wiped off by performing a so-called wiping operation in which the cleaning blade 86 slides on the ink ejection surface 50a.

  During printing or standby, when a specific nozzle is used less frequently and the ink viscosity in the vicinity of the nozzle increases, preliminary ejection is performed toward the cap 84 to discharge the deteriorated ink.

  Further, when bubbles are mixed in the ink in the recording head 50 (in the pressure chamber 52), the cap 84 is applied to the recording head 50, and the ink in the recording head 50 (ink mixed with bubbles) is sucked by the suction pump 87. The removed and sucked ink is sent to the collection tank 88. In this suction operation, the deteriorated ink that has increased in viscosity (solidified) is sucked when the initial ink is loaded into the recording head 50 or when the ink is used after being stopped for a long time.

  If the recording head 50 is not ejected for a certain period of time, the ink solvent near the nozzles evaporates and the viscosity of the ink near the nozzles increases, and the ejection drive actuator (piezoelectric element 58) operates. Ink is not discharged from the nozzle 51. Therefore, before this state is reached (within the viscosity range in which ink can be ejected by the operation of the piezoelectric element 58), the piezoelectric element 58 is operated toward the ink receiver, and the ink in the vicinity of the nozzle whose viscosity has increased is removed. “Preliminary discharge” is performed. Further, after the dirt on the ink discharge surface 50a is cleaned by a wiper such as a cleaning blade 86 provided as a cleaning means for the ink discharge surface 50a, foreign matters are mixed in the nozzle by this wiper rubbing operation (wiping operation). In order to prevent this, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  Further, if bubbles are mixed into the nozzle 51 or the pressure chamber 52 or if the ink viscosity in the vicinity of the nozzle exceeds a certain level, ink cannot be ejected by the preliminary ejection, and the suction operation described below is performed.

  That is, when bubbles are mixed in the ink in the nozzle 51 or the pressure chamber 52, or when the ink viscosity in the vicinity of the nozzle rises to a certain level or more, the ink cannot be ejected from the nozzle even if the piezoelectric element 58 is operated. . In such a case, the cap 84 is brought into contact with the ink discharge surface 50a of the recording head 50 as a suction means for sucking the ink in the pressure chamber 52 with a pump or the like, and the ink containing the bubbles or the thickened ink is sucked. Is done.

[Nozzle plate manufacturing method]
Next, an example of the nozzle plate manufacturing method according to the present invention will be described.

  7 and 8 are process diagrams showing a method for manufacturing the nozzle plate 60 of the present embodiment. Hereinafter, the manufacturing method of the nozzle plate 60 will be described with reference to these drawings.

First, as shown in FIG. 7A, a single crystal silicon substrate 200 is prepared in which the crystal plane orientation (100) plane is the first main surface 200a and the second main surface 200b. A silicon oxide film (SiO ₂ film) 202 is formed on the entire surface of the single crystal silicon substrate 200 by, eg, thermal oxidation.

  Next, as shown in FIG. 7B, a resist layer 204 is formed on the silicon oxide film 202 on the first main surface 200 a side and the second main surface 200 b side of the single crystal silicon substrate 200. Specifically, a resist (photosensitive resin) is applied to the entire surface of the silicon oxide film 202 on the first main surface 200a side and the second main surface 200b side, and the tapered hole 51a of the constricted nozzle 51 (FIG. 5). The exposure is performed from the first main surface 200a side through a mask pattern corresponding to the reference), and development is performed. In this way, as shown in FIG. 7B, the resist layer 204A having the opening 204a is patterned on the first main surface 200a side of the single crystal silicon substrate 200. On the other hand, the resist layer 204 </ b> B is disposed on the entire surface of the silicon oxide film 202 on the second main surface 200 b side of the single crystal silicon substrate 200.

  Next, as shown in FIG. 7C, the silicon oxide film 202 is etched with hydrogen fluoride (hydrofluoric acid) or the like using the resist layer 204 (204A, 204B) formed as described above as a mask. Thus, the silicon oxide film 202 exposed from the opening 204a (see FIG. 7B) of the resist layer 204A on the first main surface 200a side is removed. Thus, the first main surface 200a (that is, the crystal plane orientation (100) plane) of the single crystal silicon substrate 200 where anisotropic etching is started is exposed. Thereafter, the resist layer 204 (204A, 204B) on the first main surface 200a side and the second main surface 200b side is removed.

  Next, as shown in FIG. 7D, the single crystal silicon substrate 200 is anisotropically etched using the silicon oxide film 202 formed as described above as a mask. For anisotropic etching, KOH, TMAH, or the like is used as an etchant. Etching conditions include liquid concentration and temperature, and these may be selected as appropriate according to the situation. For example, with KOH, the concentration is 40 to 50 wt% and the temperature is 70 to 80 ° C. In TMAH, the concentration is 30 to 40 wt% and the temperature is 80 to 90 ° C. When the anisotropic etching is performed, the exposed portion of the single crystal silicon substrate 200 that is not covered with the silicon oxide film 202 is removed by etching, and as shown in FIG. An inclined surface 206 formed of a crystal plane orientation (111) surface that is inclined by about 55 degrees with respect to the first main surface 200a of the single crystal silicon substrate 200 to be formed appears. Thus, a tapered hole 208 that gradually narrows from the first main surface 200a of the single crystal silicon substrate 200 toward the second main surface 200b is formed.

  Thereafter, as shown in FIG. 7E, the silicon oxide film 202 is removed with hydrogen fluoride (hydrofluoric acid) or the like. FIG. 7F shows a plan view of the single crystal silicon substrate 200 of FIG. 7E viewed from the second main surface 200b side.

  In the manufacturing method described above, the surface on which anisotropic etching is started (the first main surface 200a of the single crystal silicon substrate 200) is composed of the crystal plane orientation (100) plane. The crystal plane orientation of the plane where anisotropic etching is started is not particularly limited.

  In the present invention, the first main surface 200a of the crystalline silicon substrate 200 is preferably constituted by a crystal plane orientation (100) plane. That is, by setting the plane where anisotropic etching is started as the crystal plane orientation (100) plane, as shown in FIG. 7F, the tapered hole 208 is rotationally symmetric four times with respect to the nozzle center axis. (That is, the nozzle 51) can be formed, the symmetry of the nozzle 51 is high, and the ejection direction is stable.

  Further, in this manufacturing method, anisotropic etching is performed using the silicon oxide film 202 as a mask after removing the resist layer 204, but the silicon oxide film 202 alone cannot be used as a mask for anisotropic etching. In another embodiment, the resist layer 204 may be left as it is without being removed and the resist layer 204 may be used as a mask for anisotropic etching.

  Next, as shown in FIG. 8A, a resist 210 is disposed on the first main surface 200 a side, the second main surface 200 b side, and inside the tapered hole 208 of the single crystal silicon substrate 200. At this time, a glass substrate 212 is arranged on the first main surface 200a side of the single crystal silicon substrate 200. A method for arranging the resist 210 using the glass substrate 212 will be described later.

  Next, as shown in FIG. 8B, the single crystal silicon substrate 200 in which the tapered hole 208 is formed is used as a mask from the first main surface 200a of the single crystal silicon substrate 200 toward the second main surface 200b. The resist 210 on the second main surface 200b side is exposed in an inversely tapered shape that gradually increases in the direction. Specifically, light (parallel light) emitted from a light source (not shown) is incident at an oblique angle that is not perpendicular to the surface of the glass substrate 212 (the surface opposite to the single crystal silicon substrate 200 side). Thus, exposure is performed while rotating the glass substrate 212 side about an axis perpendicular to the surface of the glass substrate 212 in a state where the glass substrate 212 side including the single crystal silicon substrate 200 and the resist 210 is inclined obliquely ( Hereinafter, it is referred to as “tilt rotation exposure”. The arrow shown in FIG. 8B represents a state in which light is irradiated to the resist 210 from the glass substrate 212 side by tilt rotation exposure.

  Further, in place of the tilt rotation exposure, a light diffusion plate (not shown) in a state where the glass substrate 212 side including the single crystal silicon substrate 200 and the resist 210 is fixed vertically without being inclined with respect to the light irradiation direction. There is also a mode in which exposure is performed via the above (hereinafter referred to as “diffuse light exposure”). Since light (parallel light) emitted from the light source passes through the light diffusing plate and becomes diffused light, exposure similar to tilt rotation exposure can be performed as shown in FIG. 8B.

  When the single crystal silicon substrate 200 is anisotropically etched under suitable etching conditions, the surface (namely, the inclined surface 206) that appears as a result is a crystal surface, so that the surface roughness is small. For this reason, when the tilt rotation exposure or the diffused light exposure is performed as described above, the irradiation light from the glass substrate 212 side is reflected accurately and efficiently on the inclined surface 206 as shown in FIG. 8B. Therefore, the resist 210 on the second main surface 200b side of the single crystal silicon substrate 200 can be exposed to a wide angle by the reflected light.

  When the resist 210 is developed after such tilt rotation exposure or diffuse light exposure, as shown in FIG. 8C, a wide-angle reverse tapered shape is formed on the second main surface 200b side of the single crystal silicon substrate 200. The resist pillar 210a can be obtained.

  Next, as shown in FIG. 8D, a functional film 214 is formed on the second main surface 200b side of the single crystal silicon substrate 200 using the resist pillar 210a obtained as described above as a mold. At this time, two or more functional films 214 may be formed. Examples of the method of forming the functional film 214 include a method of forming a metal film by plating, a method of forming a resin film by coating, and the like. In the functional film 214 thus obtained, the reverse tapered hole 216 corresponding to the outer shape of the resist pillar 210a is highly accurate without being displaced corresponding to the tapered hole 208 of the single crystal silicon substrate 200. Formed.

  Finally, as shown in FIG. 8E, the glass substrate 212 is peeled off and the resist 210 (including the resist pillar 210a) is removed. Thus, the nozzle plate 60 composed of the single crystal silicon substrate 200 and the functional film 214 can be obtained.

  In this manufacturing method, as shown in FIG. 8B, exposure is performed from the glass substrate 212 side in a state where the glass substrate 212 is arranged on the first main surface 200 a side of the single crystal silicon substrate 200. In the practice of the present invention, it is not always necessary to dispose the glass substrate 212. However, the glass substrate 212 used in the present manufacturing method or the like is flat so as to transmit light (for example, UV light) used in exposure. It is preferable to perform exposure in a state where a simple substrate (light transmissive substrate) is disposed on the first main surface 200a side of the single crystal silicon substrate 200. Since the irradiation light (incident light) to the resist 210 is stabilized, the shape accuracy of the resist pillar 210a (see FIG. 8C) obtained after development is improved. As a result, the reverse tapered hole 51b (particularly the ink discharge side opening edge (nozzle edge)) of the constricted nozzle 51 can be formed with high accuracy, and the discharge stability is improved.

  More preferably, both surfaces of the light-transmitting substrate (glass substrate 212) are parallel and flat. Irradiation light to the resist 210 can be further stabilized.

  There may also be a mode in which the surface of the light-transmitting substrate (glass substrate 212) on the single crystal silicon substrate 200 side (side in contact with the resist 210) is roughened. That is, as shown in FIG. 9, the surface on which the irradiation light is incident (the lower surface in FIG. 9) of the glass substrate 212 which is a light-transmitting substrate is flattened, while the opposite surface (the upper surface in FIG. 9). ). Thus, by roughening the surface of the glass substrate 212 on the single crystal silicon substrate 200 side (the side in contact with the resist 210), the adhesion of the resist 210 to the glass substrate 212 is improved, and the glass substrate 212 during the manufacturing process is improved. Peeling can be prevented. Further, since the light (parallel light) emitted from the light source passes through the rough surface of the glass substrate 212 (the surface on the single crystal silicon substrate 200 side), it becomes scattered light (see FIG. 9). Development is performed in the same manner as in the case of performing oblique rotation exposure or diffused light exposure by performing parallel light incident on the glass substrate 212 side including the single crystal silicon substrate 200 and the resist 210 without performing diffused light exposure. Later, a wide-angle inversely tapered resist pillar 210a can be obtained, and the manufacturing process can be simplified.

  In this manufacturing method, when the resist 210 is disposed on the first main surface 200a side, the second main surface 200b side, and the tapered hole 208 of the single crystal silicon substrate 200, the glass substrate 212 is used as follows. Is preferred.

  FIG. 10 is an explanatory view showing an example of a method for arranging the resist 210 using the glass substrate 212. First, as shown in FIG. 10A, a resist 210 is applied (coated) on a glass substrate 212. Next, as shown in FIG. 10B, the first main surface 200a side of the single crystal silicon substrate 200 in which the tapered hole portion 208 is formed faces the glass substrate 212 side, and the resist 210 on the glass substrate 212 is placed. The single crystal silicon substrate 200 is pressed against the glass substrate 212 side in a state of sandwiching. The resist 210 gradually enters the tapered hole 208, and finally the tapered hole 208 is filled with the resist 210. At this time, it is preferable to carry out to such an extent that a small amount of resist 210 protrudes from the opening part of the tapered hole 208 on the second main surface 200b side. Since the resist 210 can be completely filled in the tapered hole 208, residual bubbles are not generated, and adverse effects during exposure can be prevented.

  In a state where the resist 210 is filled in the tapered hole 208 as described above, preferably, a small amount of the resist 210 protrudes from the opening on the second main surface 200b side of the tapered hole 208 as shown in FIG. As shown in c), a resist 210 is applied to the second main surface 200b side of the single crystal silicon substrate 200. Thus, the resist 210 can be disposed on the first main surface 200 a side, the second main surface 200 b side, and the tapered hole 208 of the single crystal silicon substrate 200.

  As described above, according to the method of disposing the resist 210 using the glass substrate 212, the tapered hole 208 can be completely filled with the resist 210, and the glass substrate 212 and the single crystal silicon can be filled. It is also possible to obtain an effect in which the substrate 200 is brought into close contact with the resist 210 instead of the adhesive.

  In this manufacturing method, at the stage where the tapered hole 208 is formed in the single crystal silicon substrate 200 (see FIG. 7E), a substrate (for example, a flow path substrate or the like) to which the nozzle plate 60 is to be bonded is finally formed. You may make it join to the 1st main surface 200a of the single crystal silicon substrate 200. FIG. Handleability in the subsequent process is improved. At this time, it is preferable that the substrate to which the nozzle plate 60 is finally bonded is also made of silicon. Since there is no difference in coefficient of thermal expansion, it is possible to prevent warping between substrates, and since it can be bonded to the nozzle plate 60 by direct bonding of silicon, it is not necessary to use an adhesive and has excellent chemical resistance. The recording head 50 can be obtained.

  Further, in the stage before removing the silicon oxide film 202 (see FIG. 7D), the substrate (for example, a flow path substrate) to which the nozzle plate 60 is to be bonded finally is the first of the single crystal silicon substrate 200. It may be bonded to the silicon oxide film 202 on the main surface 200a side. In this case, the silicon oxide film 202 on the second main surface 200b side of the single crystal silicon substrate 200 may be removed after bonding.

  In this manufacturing method, the functional film 214 may be formed by eutectoid plating containing a fluororesin. According to this aspect, a highly accurate liquid repellent film can be simultaneously formed as the functional film 214, and since it is a metal, it has high rigidity and little damage during wiping. Further, the position of the meniscus is determined by both the shape and the liquid repellency, and the discharge performance is further improved.

  Further, in the present manufacturing method, after forming the tapered hole 208 in the single crystal silicon substrate 200 by anisotropic etching (FIG. 7B), before placing the resist 210 in a predetermined position (FIG. 8A), There is also an aspect in which a metal film is formed on the second main surface 200 b side of the single crystal silicon substrate 200.

  That is, as shown in FIG. 11 (a), as shown in FIG. 11 (b), the single crystal silicon substrate 200 has a tapered hole 208 formed by anisotropic etching. A metal film 220 is formed on the second main surface 200b side. As a method of forming the metal film 220, there is a method of forming a film of nickel (Ni) or the like by sputtering or vapor deposition. Subsequently, as shown in FIG. 11C, the first main surface 200a side, the second main surface 200b side, and the tapered hole of the single crystal silicon substrate 200 are used by using the method described in FIG. A resist 210 is disposed inside the portion 208. At this time, by arranging the glass substrate 212 on the first main surface 200a side of the single crystal silicon substrate 200, the light irradiated to the resist 210 can be stabilized. Next, when tilt rotation exposure or diffuse light exposure is performed and development is performed, as shown in FIG. 11D, a wide-angle inversely tapered resist column 210a is formed on the second main surface 200b side of the single crystal silicon substrate 200. Obtainable. Using the resist pillar 210a thus obtained as a mold, a functional film 214 is formed on the metal film 220 as shown in FIG. Examples of the method for forming the functional film 214 include methods such as electroplating and electroless plating. After that, as shown in FIG. 11F, the glass substrate 212 is peeled off and the resist 210 (including the resist pillar 210a) is removed, so that the metal film 220 is formed between the single crystal silicon substrate 200 and the functional film 214. The arranged nozzle plate 60A can be obtained.

  Generally, silicon (Si) is a difficult-to-plating material as it is, and electroless plating is possible by performing a catalytic treatment, but if a resist is applied after the catalytic treatment, the effect of the catalytic treatment is reduced. . In addition, when the catalyst treatment is performed after resist patterning, the resist may be damaged by the treatment liquid. Therefore, as described above, after the tapered hole 208 is formed in the single crystal silicon substrate 200 by anisotropic etching, before the resist 210 is placed at a predetermined position, the second main surface 200b of the single crystal silicon substrate 200 is formed. An embodiment in which the metal film 220 is formed on the side is preferable. According to this aspect, electroplating can be performed using the metal film 220 as an electrode, and the plating time can be shortened. In addition, electroless plating can be performed using the metal film 220 as a base, and in this case, a catalytic step is not required.

  In addition, in this manufacturing method, there is an aspect in which the functional film 214 having two or more layers is formed. That is, as shown in FIG. 12A, after forming a wide-angle inversely tapered resist pillar 210a on the second main surface 200b side of the single crystal silicon substrate 200, as shown in FIG. A first functional film 214 </ b> A is formed on the second main surface 200 b of the silicon substrate 200. Subsequently, as shown in FIG. 12C, a second functional film 214B is formed on the first functional film 214A. Thereafter, the glass substrate 212 is peeled off and the resist 210 (including the resist pillars 210a) is removed, so that the second main surface 200b side (ink ejection side) of the single crystal silicon substrate 200 as shown in FIG. Thus, the nozzle plate 60B on which two layers of functional films 214A and 214B are formed can be obtained.

  As described above, according to the aspect in which the functional film 214 having two or more layers is formed, various effects can be obtained by changing the function of the functional film 214 for each layer.

  For example, in the case where the above-described two-layer functional films 214A and 214B are formed (see FIG. 12), the first functional film 214A is made of a soft material, and the second functional film 214B is made of a hard material. Thus, the abrasion resistance of the second functional film 214B is improved, and the first functional film 214A absorbs an impact at the time of collision of paper or the like and is hardly damaged.

  In addition, the liquid repellency of the first functional film 214A and the second functional film 214B can be changed. For example, when the contact angle of the first functional film 214A with respect to ink is θ1, and the contact angle of the second functional film 214B with respect to ink is θ2, the first and second functions are set so as to satisfy θ1> θ2. By selecting the material of the functional films 214A and 214B, the ink around the nozzles can easily move from the first functional film 214A to the second functional film 214B, and the ink around the nozzles can be easily removed, and the ejection can be performed. Performance is improved.

  Alternatively, the first functional film 214A may be formed of a highly liquid-repellent film (liquid-repellent film), and the second functional film 214B may be formed of a highly scratch-resistant film. Since the wiping blade is not applied to the first functional film 214A at the time of wiping, the durability is improved by providing the second functional film 214B with wiping durability. Further, since the first functional film 214A has liquid repellency, it is easy to remove ink around the nozzles.

  In this manufacturing method, as described above, the exposure is performed using the reflected light from the silicon crystal surface (inclined surface 206) that has appeared by anisotropic etching. However, the reflected light is used in the practice of the present invention. It is not limited to the embodiment.

  That is, as shown in FIG. 13, there is also an aspect in which exposure is performed without reflecting the light irradiated to the silicon crystal surface (inclined surface 206) that appears by anisotropic etching of the single crystal silicon substrate 200. Specifically, as shown in FIG. 14A, a mask 222 in which an opening pattern corresponding to the tapered hole 208 of the single crystal silicon substrate 200 is formed between a glass substrate 212 and a light source (not shown). In addition to the glass substrate 212 side including the single crystal silicon substrate 200 and the resist 210, tilt rotation exposure while rotating the mask 222 in a state where the mask 222 is tilted with respect to the light (parallel light) irradiation direction. I do. Further, as shown in FIG. 14B, the position corresponding to the tapered hole 208 of the single crystal silicon substrate 200 is on the opposite side of the glass substrate 212 from the single crystal silicon substrate 200 side (the side in contact with the resist 210). In addition, light (parallel light) may be irradiated in a state where a mask 224 on which a light diffusion portion 224a is disposed is disposed. The region 224b other than the light diffusion portion 224a of the mask 224 is a light blocking region, and the irradiated light (parallel light) becomes diffused light when passing through the diffusion portion 224a of the mask 224, and the resist 210 is exposed as shown in the figure. Is called. It is preferable to perform the mask 224 in close contact with the glass substrate 212 because the resist 210 can be accurately exposed.

  As described above, according to the present manufacturing method, the single crystal silicon substrate 200 in which the tapered hole 208 is formed by anisotropic etching is used as a mask to the second main surface 200b side (ink) of the single crystal silicon substrate 200. By exposing the resist 210 on the discharge side to a reverse taper shape, it is possible to obtain a high-precision resist column 210a that is not displaced with respect to the tapered hole 208 of the single crystal silicon substrate 200 after development. A functional film 214 having a reverse tapered hole 216 corresponding to the outer shape of the pillar 210 a can be formed on the second main surface 200 b side of the single crystal silicon substrate 200. As a result, a highly accurate constricted nozzle 51 composed of the tapered hole 51a (208) and the reverse tapered hole 51b (216) can be collectively formed.

  In particular, according to the aspect in which the exposure is performed by reflecting the light irradiated to the silicon crystal surface (inclined surface 206) that appears by anisotropic etching of the single crystal silicon substrate 200, generally under appropriate etching conditions. Since the surface roughness of the silicon crystal surface that appears in the anisotropic etching performed becomes small, the reflected light from the silicon crystal surface can be used efficiently and accurately during exposure, and the reflected light from the silicon crystal surface is not used. As compared with the case where the exposure is performed in the above, a reverse-tapered resist pillar 210a having a wider angle can be obtained (see FIG. 8C). Therefore, the degree of freedom of the shape of the reverse tapered portion 51b of the constricted nozzle 51 is improved, the protection effect of the nozzle is increased, and the discharge stability is improved.

  Although the nozzle plate manufacturing method, nozzle plate, liquid ejection head, and image forming apparatus of the present invention have been described in detail above, the present invention is not limited to the above examples and does not depart from the spirit of the present invention. Of course, various improvements and modifications may be made.

Overall configuration diagram showing outline of inkjet recording apparatus Main part plan view showing the periphery of the printing unit of the ink jet recording apparatus Plane perspective view showing structure example of recording head Sectional drawing which shows the three-dimensional structure of one droplet discharge element Enlarged cross section around the nozzle Schematic diagram showing the configuration of an ink supply system in an inkjet recording apparatus Process chart showing nozzle plate manufacturing method Process chart showing nozzle plate manufacturing method Explanatory drawing which showed the aspect which roughens one side of a glass substrate Explanatory drawing showing how to arrange resist using glass substrate Explanatory drawing which showed the aspect which forms a metal film in the 2nd main surface side of a single crystal silicon substrate Explanatory drawing which showed the aspect which forms the functional film of two layers Explanatory drawing which showed the aspect exposed without using the reflected light by a silicon crystal plane Explanatory drawing which showed the aspect exposed without using the reflected light by a silicon crystal plane

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording apparatus 50 ... Recording head 51 ... Nozzle 52 ... Pressure chamber 54 ... Ink supply port 55 ... Common liquid chamber 58 ... Piezoelectric element 60 ... Nozzle plate 62 ... Single crystal silicon substrate 64 ... Functional film, 200 ... Single crystal silicon substrate, 202 ... Silicon oxide film, 204 ... Resist, 206 ... Inclined surface, 208 ... Tapered hole, 210 ... Resist, 210a ... Resist pillar, 212 ... Glass substrate, 214 ... Functional film, 216, reverse tapered hole, 220, metal film

Claims (14)

A step of anisotropically etching the single crystal silicon substrate to form a tapered hole gradually narrowing from the first main surface of the single crystal silicon substrate toward the second main surface;
Forming a resist on at least the second main surface side of the single crystal silicon substrate;
Exposing the resist in a reverse taper shape gradually widening from the first main surface toward the second main surface using the single crystal silicon substrate in which the tapered hole is formed as a mask;
Developing the resist;
Forming a functional film on the second main surface side of the single crystal silicon substrate;
Removing the resist;
The manufacturing method of the nozzle plate characterized by including.   2. The method of manufacturing a nozzle plate according to claim 1, wherein the first main surface of the single crystal silicon substrate is formed of a crystal plane orientation (100) plane.   The method for manufacturing a nozzle plate according to claim 1, wherein the resist is exposed using light reflected on a surface exposed by the anisotropic etching.   4. The light-transmitting substrate is disposed on the first main surface side of the single crystal silicon substrate, and the resist is exposed through the light-transmitting substrate. 2. A method for producing a nozzle plate according to item 1.   The method for manufacturing a nozzle plate according to any one of claims 1 to 4, wherein the functional film is a resin film or a metal film.   The method for manufacturing a nozzle plate according to claim 1, wherein the functional film is a film having liquid repellency with respect to ink.   The method for producing a nozzle plate according to claim 6, wherein the functional film is formed by eutectoid plating containing a fluororesin. After anisotropically etching the single crystal silicon substrate, further comprising forming a metal film on the surface of the second main surface of the single crystal silicon substrate;
The method for manufacturing a nozzle plate according to claim 1, wherein the functional film is formed on the surface of the metal film after the exposure and development. Nozzle plate formed with a constricted nozzle composed of a tapered hole portion that gradually narrows toward the liquid discharge side and a reverse tapered hole portion that gradually widens from the tapered hole portion toward the liquid discharge side Because
The tapered hole is formed in the single crystal silicon substrate, and the reverse tapered hole is formed in a functional film disposed on the liquid discharge side of the single crystal silicon substrate,
The nozzle plate according to claim 1, wherein the functional film is made of a material different from that of the single crystal silicon substrate.   The opening on the liquid discharge side of the tapered hole formed in the single crystal silicon substrate and the opening on the side opposite to the liquid discharge side of the reverse tapered hole formed in the functional film have the same shape. The nozzle plate according to claim 9.   The surface opposite to the liquid discharge side of the single crystal silicon substrate is constituted by a crystal plane orientation (100) plane, and the inner wall surface of the tapered hole portion is constituted by a crystal plane orientation (111) plane. The nozzle plate according to claim 9 or 10, wherein the nozzle plate is characterized.   The inclination angle of the inner wall surface of the inversely tapered hole portion formed in the functional film with respect to the nozzle axis is wider than the inclination angle of the inner wall surface of the tapered hole portion formed in the single crystal silicon substrate with respect to the nozzle axis. The nozzle plate according to any one of claims 9 to 11, wherein the nozzle plate is characterized in that   A liquid discharge head comprising the nozzle plate according to any one of claims 9 to 12.   An image forming apparatus comprising the liquid discharge head according to claim 13.

Images