JP6312961B2 - Method for manufacturing nozzle plate of inkjet head - Google Patents

Description

  The present invention relates to a nozzle plate for an inkjet head that forms an image by ejecting ink onto a recording medium, and a method for manufacturing the same.

  Conventionally, as an image forming method on a recording medium, a method of forming a desired image by ejecting ink from an inkjet head onto a recording medium is known.

  In the inkjet head, nozzles for ejecting ink are formed on the ejection surface, and an ink flow path communicating with the nozzles is formed therein. Then, ink supplied from the ink tank flows through the ink flow path and fills the nozzles. A pressure chamber is formed in a part of the ink flow path, and a predetermined amount of ink is ejected from the nozzle by changing the ink pressure in the pressure chamber.

  When an inkjet head is manufactured, a manifold having a portion corresponding to the ink flow path and a nozzle plate having a minute hole are stacked and integrated to form an ink flow path. It is.

  When manufacturing the nozzle plate, the nozzle plate is often subjected to water repellent treatment so that the discharged ink does not adhere to the discharge surface on which the nozzle is formed. For example, Patent Document 1 describes that a through hole is formed in a film by a photolithography method, and a protective film for a diamond-like carbon film or a fluorine-added diamond-like carbon film is provided. Patent Document 2 describes a method for manufacturing a discharge head in which a diamond thin film is formed on the surface where the discharge port of the discharge head is located.

JP 2000-229413 A JP 2012-101548 A

  In the methods of Patent Document 1 and Patent Document 2 described above, the water repellent coating is unevenly formed, and there is a possibility that not only the outer surface of the nozzle but also the inside of the nozzle may be subjected to water repellent treatment. Further, in order to prevent the water-repellent treatment inside the nozzle, complicated processing such as masking processing must be performed, leading to an increase in manufacturing steps.

  Therefore, the present invention provides a nozzle plate for an inkjet head that can easily perform water-repellent treatment on the ejection surface on which the nozzle is formed and hydrophilic treatment inside the nozzle without performing complicated processing such as masking. The object is to provide a manufacturing method.

A method for manufacturing a nozzle plate for an inkjet head according to the present invention is a method for manufacturing a nozzle plate for an inkjet head in which nozzle holes are formed. The nozzle holes are formed in the nozzle plate, and fluorine is added from the discharge surface side of the nozzle plate. After performing diamond-like carbon processing and forming a water-repellent coating on the discharge surface of the nozzle plate, diamond-like carbon processing is performed from the surface opposite to the discharge surface of the nozzle plate, A hydrophilic coating that is more hydrophilic than the water-repellent coating is formed on the surface and inside the nozzle hole. Furthermore, the shape of the cross section along the plate stacking direction of the nozzle holes is formed of a tapered portion and a straight portion.

  By having the above-described configuration, the present invention can easily perform water-repellent treatment on the discharge surface on which the nozzle is formed and hydrophilic treatment inside the nozzle without performing complicated processing such as masking. It becomes possible.

It is a schematic block diagram regarding the plate which comprises an inkjet head. It is a flow which shows the manufacturing process of a nozzle plate. It is explanatory drawing regarding the manufacturing process of a nozzle plate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic configuration diagram relating to a plate constituting the inkjet head 1. The inkjet head 1 includes a plurality of nozzle plates 10 in which a plurality of nozzles for ejecting ink are formed and a plurality of notches for forming a flow path for supplying ink to the nozzles (three in the figure). A flow path plate 20, two pressure chamber plates 30 each having a notch for forming a pressure chamber (not shown) communicating with each nozzle through the formed flow path, and a piezoelectric element. The vibration plate 40 is configured to transmit a pressure wave generated by the deformation 50 to the pressure chamber, and a rigidity reinforcing plate 60 for reinforcing the vibration plate 40. In this example, a plate other than the nozzle plate 10 corresponds to the head plate. The configuration of the head plate may be changed in shape and number according to the inkjet head to be manufactured, and is not limited to this example.

  The pressure chamber formed by the pressure chamber plate 30 is provided with a restrictor (not shown) that is a throttle channel for supplying ink. The restrictor receives ink from an ink tank (not shown). A supply channel (not shown) is connected.

  Further, these plates are molded from, for example, a metal material, and the notches for the flow paths and pressure chambers formed in the plate are patterned by, for example, etching the metal material. As the metal material used for the plate, stainless steel is preferable from the viewpoint of ink resistance, and it can cope with highly corrosive ink such as ultraviolet curable ink. In addition, by using the same metal material as each plate, deformation during heating or cooling in the manufacturing process occurs in the same way in each plate, so that distortion between the plates does not occur and manufacturing errors can be reduced. It becomes.

  On the surface of the vibration plate 40, a plurality of piezoelectric elements 50, which are ink ejection drive sources, are independently mounted at mounting positions corresponding to the pressure chambers. The piezoelectric elements 50 that are individually manufactured in advance are bonded and fixed to the respective mounting positions. Therefore, when a failure occurs in some of the piezoelectric elements, only the defective piezoelectric element can be replaced, and the number of defective inkjet heads is reduced compared to the case where the piezoelectric element is integrally formed on the vibration plate. be able to. Further, when the layout of the inkjet head is changed, the mounting position of the piezoelectric element may be set in accordance with the change, and the piezoelectric element can be easily mounted.

  A signal cable (not shown) is connected to each piezoelectric element 50, and an electric signal can be given to each piezoelectric element 50 independently. By applying an electrical signal to each piezoelectric element 50 via the signal cable, each piezoelectric element 50 is distorted. As a result, the vibration plate 40 is displaced and is joined to the vibration plate 40. The volume in the 30 pressure chambers expands and contracts, pressure waves are applied to the ink filled in the pressure chambers, and ink is ejected from the nozzles.

  The manufacturing process of the nozzle plate 10 will be described below. FIG. 2 is a flow relating to the manufacturing process of the nozzle plate 10. First, a stainless plate is prepared as the nozzle plate 10. The nozzle plate 10 may be made of other materials such as nickel or silicon other than stainless steel. The prepared plate is cleaned to remove impurities and the like. Next, nozzle holes are formed in the nozzle plate by pressing. After removing the flash generated during the pressing process by polishing or the like, it is preferable to inspect whether there is any problem in the shape of the nozzle. Further, if the nozzle hole has a tapered shape in which the cross-sectional shape along the plate stacking direction is inclined at a predetermined angle, the size of the ejected ink droplets can be made almost constant, and the landing accuracy can be improved. It is preferable because it is an excellent nozzle plate. Here, an example in which the nozzle hole has a tapered portion and a straight portion will be described. By making the ejection tip portion of the nozzle hole into a straight portion, the ejection direction of the ink droplets can be stabilized and the landing accuracy can be further improved. In addition, about the formation method of a nozzle hole, you may carry out using other methods, such as a punching process, electric discharge machining, and laser processing, instead of press working.

  Next, as shown in FIG. 3 (a), a fluorinated diamond-like carbon (fluorine-added carbon) is added from the discharge surface side with the cover plate 4 laid and the discharge surface on which the nozzle holes of the nozzle plate 10 are formed facing upward. DLC) processing. By this treatment, the water repellent coating 2 can be applied to the discharge surface side of the nozzle plate 10. Note that a water-repellent film is formed not only on the ejection surface side (nozzle hole outer surface) of the nozzle plate 10 but also near the inlet (injection tip portion) inside the nozzle hole. Since a hydrophilic film can be formed inside the nozzle in the process, it is not necessary to perform a process such as masking.

  Then, as shown in FIG. 3B, with the nozzle plate 10 turned upside down and the discharge surface on which the nozzle holes are formed facing down, the diamond-like carbon is formed from the inner side of the nozzle holes (opposite the discharge surface). (DLC) Processing is performed. In this case, the DLC process only needs to be hydrophilic in comparison with the fluorine-added DLC process in the previous step. DLC processing that contains nitrogen or the like and has higher hydrophilicity may also be used. By this processing, the hydrophilic coating 3 that is more hydrophilic than the discharge surface side of the nozzle plate 10 is applied to the inside of the nozzle holes of the nozzle plate 10. In addition, about the DLC process in each process mentioned above, it can implement by conventionally well-known methods, such as a chemical vapor deposition method (CVD method) and an ion plating method.

  Usually, when other coatings having properties such as hydrophilicity are applied on the water-repellent coating, for example, when coating with a resin, the resin coated with the water-repellent coating is repelled, and the coating is successfully performed. It is difficult to form a coating on the surface. However, in the case of DLC processing, it is possible to form another film on the water-repellent film. For this reason, the surface of the water-repellent coating formed by the fluorine-added DLC processing is a state in which fluorine is finely dispersed in the carbon film. When the DLC processing is performed on the surface, the DLC coating becomes a fluorine-added DLC. This is considered to be because the DLC film can be formed so as to first bond with the carbon of the film and then cover the fluorine.

  The nozzle plate manufactured in this way exhibits water repellency on the ejection surface side and hydrophilicity inside the nozzle without performing complicated processing such as masking. Further, since the adhesive surface of the nozzle plate with the flow path plate becomes hydrophilic, the adhesive can be uniformly applied to the adhesive surface, and the adhesiveness with the flow path plate is improved. And since the inside of a nozzle hole is hydrophilic in the inkjet head using this nozzle plate, the discharge property of a bubble improves because an ink spreads uniformly. Further, since the discharge surface side of the nozzle plate is water-repellent, the ink can be reliably wiped off during the wiping process of the inkjet head. Furthermore, since the film to be formed is a DLC film, the wear resistance and chemical resistance are also excellent.

DESCRIPTION OF SYMBOLS 1 Inkjet head 10 Nozzle plate 20 Flow path plate 30 Pressure chamber plate 40 Vibration plate 50 Piezoelectric element 60 Stiffening plate 2 Water-repellent coating 3 Hydrophilic coating 4

Claims (2)

A method of manufacturing a nozzle plate of an inkjet head in which nozzle holes are formed,
Form nozzle holes in the nozzle plate,
After performing fluorine-added diamond-like carbon processing from the discharge surface side of the nozzle plate and forming a water-repellent coating on the discharge surface of the nozzle plate,
Diamond-like carbon processing is performed from the surface opposite to the discharge surface of the nozzle plate to form a hydrophilic coating that is more hydrophilic than the water-repellent coating on the surface opposite to the discharge surface of the nozzle plate and inside the nozzle hole. Do
A method for manufacturing a nozzle plate of an inkjet head. 2. The method of manufacturing a nozzle plate of an ink jet head according to claim 1, wherein the shape of the cross section of the nozzle hole along the plate stacking direction is composed of a tapered portion and a straight portion .