Abstract:
An inkjet head according to an aspect of the invention may include: a manifold storing ink being injected from the outside; ink chambers receiving the ink from the manifold to eject the ink to the outside through nozzles; and a restrictor connecting the manifold and the ink chambers to each other and providing a plurality of interconnection paths.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2009-0071755 filed on Aug. 4, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an inkjet head and a method of manufacturing the same, and more particularly, to an inkjet head that can improve printing quality and a method of manufacturing the same. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, an inkjet head converts an electric signal into a physical force so that ink droplets are ejected through small nozzles. 
         [0006]    In recent years, piezoelectric inkjet heads have been used in industrial inkjet printers. For example, a circuit pattern is directly formed by spraying ink prepared by melting metals such as gold or silver onto a printed circuit board (PCB). A piezoelectric inkjet head is also used for industrial graphics, and is used in the manufacturing of a liquid crystal display (LCD) and an organic light emitting diode (OLED). 
         [0007]    In general, an inlet and an outlet through which ink is introduced and ejected in a cartridge, a reservoir storing the ink being introduced, and chambers through which a driving force of an actuator by which the ink in the reservoir is moved to nozzles are provided in an inkjet head of an inkjet printer. 
         [0008]    A liquid inside chambers of the inkjet head according to the related art generates driving waves when an actuator being mounted adjacent to the chambers generates vibrations. These driving waves become pressure waves travelling toward a manifold through a restrictor, and the pressure waves are then transmitted to the manifold. 
         [0009]    The transmitted pressure waves cause the inkjet head according to the related art to undergo crosstalk that adversely affects neighboring nozzles. As a result, an unstable meniscus motion is observed, causing unstable droplet ejection and serving as noise in the eigenfrequency of an actuator of an adjacent ink chamber, thereby deteriorating printing quality. 
       SUMMARY OF THE INVENTION 
       [0010]    An aspect of the present invention provides an inkjet head and a method of manufacturing the same that can prevent crosstalk adversely affecting other nozzles due to driving waves generated when an actuator vibrates. 
         [0011]    According to an aspect of the present invention, there is provided a an inkjet head including: a manifold storing ink being injected from the outside; ink chambers receiving the ink from the manifold to eject the ink to the outside through nozzles; and a restrictor connecting the manifold and the ink chambers to each other and providing a plurality of interconnection paths. 
         [0012]    The interconnection paths may each have a cylindrical shape. 
         [0013]    The interconnection paths may be arranged symmetrically, relative to each other. 
         [0014]    The ink chambers and the manifold may be provided diagonally opposite each other, and the restrictor may extend diagonally from the ink chambers. 
         [0015]    The amount of ink being ejected through the interconnection paths of the restrictor may be twice as much as the amount of ink being ejected through the nozzle. 
         [0016]    The interconnection paths each may have a diameter of 50 μm or less. 
         [0017]    According to another aspect of the present invention, there is provided a method of manufacturing an inkjet head, the method including: providing a flow path plate having ink chambers therein; forming a manifold, storing ink being injected from the outside, and a plurality of interconnection paths, connecting the ink chamber and the manifold, in a nozzle plate; and forming a restrictor including a plurality of interconnection paths by bonding the flow path plate and the nozzle plate to each other. 
         [0018]    The plurality of interconnection paths may be formed at the same time by an etching process. 
         [0019]    The nozzle plate may be formed by bonding an intermediate plate having the manifold and the restrictor formed therein, and a lower plate having nozzles formed therein so as to be connected to the ink chambers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0021]      FIG. 1  is a schematic perspective view illustrating an inkjet head according to an exemplary embodiment of the present invention; 
           [0022]      FIG. 2  is a cross-sectional view illustrating the inkjet head of  FIG. 1 ; 
           [0023]      FIGS. 3A through 3E  are schematic partial perspective views illustrating the restrictors of inkjet heads according to various embodiments of the present invention; 
           [0024]      FIG. 4  is a cross-sectional view illustrating a method of manufacturing an inkjet head according to an exemplary embodiment of the present invention; 
           [0025]      FIG. 5  is a schematic cross-sectional view illustrating an inkjet head according to another exemplary embodiment of the present invention; and 
           [0026]      FIG. 6  is a schematic cross-sectional view illustrating an inkjet head according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    An inkjet head and a method of manufacturing the same according to exemplary embodiments of the invention will be described in detail with reference to  FIGS. 1 through 6 . Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
         [0028]    Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0029]      FIG. 1  is a schematic perspective view illustrating an inkjet head according to an exemplary embodiment of the invention.  FIG. 2  is a cross-sectional view illustrating the inkjet head of  FIG. 1 . 
         [0030]    Referring to  FIGS. 1 and 2 , an inkjet head according to this embodiment includes a flow path plate  110 , an intermediate plate  120 , a lower plate  130 , piezoelectric actuators  140  and a restrictor  150 . 
         [0031]    The flow path plate  110  includes a plurality of ink chambers  112  at regular intervals and has an ink introduction hole  116  through which ink is introduced. Here, the ink introduction hole  116  is directly connected with a manifold  122 . The manifold  122  supplies ink to the ink chambers  112  via a restrictor  124  (in the direction of the arrow of  FIG. 1 ). 
         [0032]    Here, the manifold  122  may be one large space to which the plurality of ink chambers  112  are connected. However, the invention is not limited thereto. A plurality of manifolds  122  may be formed to correspond to the individual ink chambers  112 . 
         [0033]    Similarly, one ink introduction hole  116  may be formed to correspond to one manifold  122 . When the plurality of manifolds  122  are formed, a plurality of ink introduction holes  116  may be formed to correspond to the individual manifolds  122 . 
         [0034]    The ink chambers  112  are provided in the flow path plate  110  at positions located under piezoelectric actuators  140 . Here, a portion of the flow path plate  110  that forms the ceiling of the ink chambers  112  serves as a vibration plate  114 . 
         [0035]    Therefore, when a driving signal is applied to the piezoelectric actuators  140  in order to eject ink, the piezoelectric actuators  140  and the vibration plate  114  thereunder are deformed to reduce the volumes of the ink chambers  112 . 
         [0036]    The reduction in the volumes of the ink chambers  112  increases the pressure inside the ink chambers  112 , so that ink inside the ink chambers  112  is ejected to the outside through dampers  126  and nozzles  132 . 
         [0037]    Electrodes electrically connected to each other may be formed on upper and lower surfaces of each of the piezoelectric actuators  140 . The electrodes may be formed of Lead Zirconate Titanate (PZT) ceramics, which is one of piezoelectric materials. 
         [0038]    The intermediate plate  120  may include the manifold  122  having a large length extending in a longitudinal direction and the dampers  126  connecting the nozzles  132  and the ink chambers  112 . 
         [0039]    The manifold  122  receives ink through the ink introduction hole  116  and supplies the ink to the ink chambers  112 . The manifold  122  and the ink chambers  112  are connected with each other through the restrictor  124 . 
         [0040]    The dampers  126  receive the ink ejected from the ink chambers  112  through the piezoelectric actuators  140  and eject the received ink to the outside through the nozzles  132 . 
         [0041]    The dampers  126  may have a multi-stage configuration by which the amount of ink ejected from the ink chambers  112  and the amount of ink ejected through the nozzles  132  can be controlled. 
         [0042]    Here, the dampers  126  are optional. When the dampers  126  are removed, the inkjet head may only include the flow path plate  110  and the lower plate  130 . 
         [0043]    The lower plate  130  corresponds to the ink chambers  112  and includes the nozzles  132  through which the ink passing through the dampers  126  is ejected to the outside. The lower plate  130  is bonded to the bottom of the intermediate plate  120 . 
         [0044]    The ink moving through a flow path formed inside the inkjet head is sprayed as ink droplets through the nozzles  132 . 
         [0045]    Here, silicon substrates being widely used for semiconductor integrated circuits may be used for the flow path plate  110 , the intermediate plate  120 , and the lower plate  130 . The intermediate plate  120  and the lower plate  130  may be bonded to each other, which construction may be referred to as a nozzle plate. 
         [0046]    The restrictor  150  connects the ink chambers  112  and the manifold  122  to each other and includes a plurality of interconnection paths  152 . Here, the restrictor  150  may extend from the bottom of the ink chambers  112 . However, the location at which the restrictor may be formed is not limited thereto. 
         [0047]    Here, the restrictor  150  serves as a passage through which the ink, stored in the manifold  122 , moves toward the ink chambers  112 . In order to realize appropriate droplet ejection, the amount of ink being ejected through the interconnection paths  152  may be twice as much as the amount of ink being ejected through the nozzles  132 . Specifically, the interconnection paths  152  each may have a diameter of 50 μm or less. 
         [0048]    Therefore, in this embodiment, the restrictor  150  having the interconnection paths  152  with the diameter of 50 μm or less can increase high frequency characteristics while maintaining droplet ejection performance. 
         [0049]      FIGS. 3A through 3E  are partial perspective views illustrating the restrictors of inkjet heads according to various embodiments of the invention. 
         [0050]    Referring to  FIGS. 3A through 3E , the restrictor  150  has the plurality of interconnection paths  152 . As shown in  FIG. 3A , the interconnection paths  152  may be arranged in contact with each other. 
         [0051]    As shown in  FIG. 3B , the plurality of interconnection paths  152  may be located symmetrically, relative to each other. Alternatively, as shown in  FIG. 3C , the plurality of interconnection paths  152  may be localized at one side of the intermediate plate  120 . 
         [0052]    As shown in  FIGS. 3D and 3E , there may be two interconnection paths  152 . The locations of the interconnection paths  152  may vary according to the designers&#39; intentions in consideration of cancellation of pressure waves. 
         [0053]    Here, a lower surface of the intermediate plate  120  which corresponds to the space of the ink chambers  112  is only illustrated in  FIGS. 3A through 3E . 
         [0054]    As shown in  FIGS. 3A through 3E , the restrictor  150  may have a circular shape in cross section. However, the restrictor  150  may have various shapes, such as rectangular and polygonal shapes, which are suitable for cancelling pressure waves. 
         [0055]    If the restrictor  150  is a single large passage having a large diameter, when the actuators  140 , mounted adjacent to the ink chambers  112 , vibrate, the liquid inside the ink chambers  112  generates driving waves. These driving waves may become pressure waves travelling toward the manifold by the restrictor  150 , which may then be transmitted to the manifold. This force may cause crosstalk affecting the neighboring nozzles  132 . 
         [0056]    However, the inkjet head according to this embodiment has the restrictor  150  that connects the manifold  122  and the ink chambers  112  to each other and includes the plurality of interconnection paths  152 . Therefore, when the actuators vibrate, pressure waves, generated from the inside of the ink chambers  112 , may be cancelled to thereby prevent crosstalk. 
         [0057]    Furthermore, the inkjet head according to this embodiment has the plurality of interconnection paths  152  each having a diameter of 50 μm or less, thereby filtering out dust that may enter the ink chambers  112  from the manifold  122 . Therefore, in this embodiment, these problems can be solved to thereby improve high frequency ejection characteristics and increase printing quality. 
         [0058]      FIG. 4  is a cross-sectional view illustrating a method of manufacturing an inkjet head according to an exemplary embodiment of the invention. 
         [0059]    Referring to  FIG. 4 , according to a method of manufacturing an inkjet head according to this embodiment, the flow path plate  110 , the intermediate plate  120  and the lower plate  130  are provided. 
         [0060]    Here, the intermediate plate  120  and the lower plate  130  may be bonded to each other, which construction may be referred to as a nozzle plate. 
         [0061]    The ink chambers  112 , the manifold  122 , the dampers  126  and the nozzles  132  may be formed in the flow path plate  110 , the intermediate plate  120  and the lower plate  130 , respectively. 
         [0062]    Here, the plurality of interconnection paths  152  may be formed at the same time by an etching process. The restrictor  150  having the plurality of interconnection paths  152  may be formed at the same time as the interconnection paths  152  are formed. Therefore, the restrictor  150  may be manufactured with ease without forming additional separate structures, thereby reducing the time required for manufacturing the same. 
         [0063]    Here, the flow path plate  110 , the intermediate plate  120  and the lower plate  130  may be bonded together to thereby form a single body. Specifically, the intermediate plate  120  is bonded to the bottom of the flow path plate  110 , and the lower plate  130  is bonded to the bottom of the intermediate plate  120 . 
         [0064]    Therefore, according to the method of manufacturing an inkjet head according to this embodiment, the restrictor  150  that connects the manifold  122  and the ink chambers  112  to each other and has the plurality of interconnection paths  152  can be manufactured with ease. 
         [0065]      FIG. 5  is a schematic sectional view illustrating an inkjet head according to another exemplary embodiment of the invention. 
         [0066]    Referring to  FIG. 5 , an inkjet head includes the flow path plate  110 , the intermediate plate  120 , the lower plate  130 , the piezoelectric actuators  140  and a restrictor  250 . 
         [0067]    The flow path plate  110 , the intermediate plate  120 , the lower plate  130  and the piezoelectric actuators  140  according to this embodiment are substantially the same as those of the embodiment, described with reference to  FIGS. 1 and 2 . Thus, a detailed description thereof will be omitted. 
         [0068]    The restrictor  250  connects the ink chambers  112  and the manifold  122  and includes a plurality of interconnection paths  252 . Here, the manifold  122  may be provided diagonally opposite the ink chambers  112 . 
         [0069]    Therefore, as shown in  FIG. 5 , the restrictor  250  may be located at the side of the ink chambers  112  in the inkjet head in order to connect the manifold  122  and the ink chambers  112 . 
         [0070]      FIG. 6  is a schematic sectional view illustrating an inkjet head according to another exemplary embodiment of the invention. 
         [0071]    Referring to  FIG. 6 , an inkjet head according to this embodiment includes the flow path plate  110 , the intermediate plate  120 , the lower plate  130 , the piezoelectric actuators  140 , and a restrictor  350 . 
         [0072]    The flow path plate  110 , the intermediate plate  120 , the lower plate  130  and the piezoelectric actuators  140  according to this embodiment are substantially the same as those of the embodiment, described with reference to  FIGS. 1 and 2 . Thus, a detailed description thereof will be omitted. 
         [0073]    The restrictor  350  connects the ink chambers  112  and the manifold  122  and includes a plurality of interconnection paths  352 . Here, the manifold  122  is located diagonally opposite the ink chambers  112 . 
         [0074]    Therefore, as shown in  FIG. 6 , the restrictor  350  may extend diagonally from the ink chambers  112  in the inkjet head in order to connect the manifold  122  and the ink chambers  112 . 
         [0075]    Therefore, the inkjet head according to this embodiment has the restrictors  250  and  350  that connect the manifold  122  and the ink chambers  112  and include the plurality of interconnection paths  252  and the plurality of interconnection paths  352 , respectively, to cancel pressure waves generated from the inside of the ink chambers  112  when the actuators vibrate, thereby preventing crosstalk. 
         [0076]    As set forth above, according to exemplary embodiments of the invention, an inkjet head and a method of manufacturing the same include a restrictor that connects a manifold and ink chambers and has a plurality of interconnection paths, thereby cancelling pressure waves generated from the inside of the ink chambers when actuators vibrate. 
         [0077]    Furthermore, the inkjet head and the method of manufacturing the same can filter dust that may enter the ink chambers from the manifold since interconnection paths have a small diameter. 
         [0078]    While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.