Patent Publication Number: US-2010107411-A1

Title: Inkjet head manufacturing method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2008-0106925, filed with the Korean Intellectual Property Office on Oct. 30, 2008, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a method of manufacturing an inkjet head. 
     2. Description of the Related Art 
     The inkjet printer can convert an electric signal to a physical force and discharge an in ink droplet through a nozzle in order to perform the printing. An inkjet head can be manufactured by processing various elements such as a chamber, a restrictor, a nozzle, and a piezoelectric element on each layer and coupling the layers to one another. 
     The inkjet head has been expansively applied to the manufacture of electronic parts, such as printed boards and LCD panels, as well as the conventional graphic inkjet industries that perform the printing on the paper or fiber. 
     Accordingly, the inkjet printing technology for electronic parts, which is required to discharge functional ink more precisely than the conventional graphic printing, requires functions that the conventional inkjet has not required. It is necessary to control the size and the speed deviation of an ink droplet. Moreover, high density nozzles and high frequency properties are required to increase the production. An actuator of the thin-film inkjet head has been developed to meet such demands. 
       FIG. 1  is a front cross-sectional view showing a conventional inkjet head  12 . In accordance with the conventional art as shown in  FIG. 1 , a piezoelectric element is adhered to one surface of the inkjet head  12 , and then dicing is performed to allow the piezoelectric element to function as an independent actuator  2  on each chamber  6 . 
     At this time, if each of the actuators  2  is completely severed, there may be serious stress on a silicon board of the inkjet head  12 . If the piezoelectric element is not completely severed, however, the adjacent actuators  2  are connected to each other, thereby causing the crosstalk. 
     If the dicing is performed twice by using a saw blade for fear of the stress of the silicon board of the inkjet head  12 , there remains a wall-shaped part  8  of the piezoelectric element between the adjacent actuators, thereby causing the crosstalk. 
     SUMMARY 
     The present invention provides a method of manufacturing an inkjet head having a thin actuator and reducing the crosstalk. 
     An aspect of present invention features a method of manufacturing an inkjet head, the inkjet head having a plurality of chambers containing ink and an actuator providing pressure to the chambers, including forming a piezoelectric element on one side of the inkjet head that is adjacent to the chambers; forming the actuator(s) by dicing the piezoelectric element such that the piezoelectric element is divided and placed corresponding to a position of the chamber(s); and etching one side of the inkjet head such that a part of the piezoelectric element remaining between the adjacent actuators is removed. 
     Here, the forming of the piezoelectric element can be performed by adhering the sintered piezoelectric element to one side of the inkjet head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front cross-sectional view showing the conventional inkjet head; 
         FIG. 2  is a lateral cross-sectional view showing an inkjet head in accordance with an embodiment of the present invention; 
         FIG. 3  is a flowchart showing an inkjet head manufacturing method in accordance with an embodiment of the present invention; 
         FIG. 4  and  FIG. 5  are plan views showing an inkjet head in accordance with an embodiment of the present invention; 
         FIG. 6  is a front cross-sectional view showing an inkjet head in accordance with an embodiment of the present invention; and 
         FIG. 7  and  FIG. 8  are front cross-sectional views showing part of an inkjet head in accordance with an embodiment of the present invention. 
     
    
    
     DETAIL DESCRIPTION 
     The features and benefits of an embodiment of the present invention will become more apparent through the below description with reference to the accompanying drawings. 
     An inkjet head manufacturing method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Identical or corresponding elements will be given the same reference numerals, regardless of the figure number, and any redundant description of the identical or corresponding elements will not be repeated. 
       FIG. 2  is a lateral cross-sectional view showing an inkjet head in accordance with an embodiment of the present invention. As shown in  FIG. 2 , an inkjet head  100  can include a reservoir  111 , a restrictor  113 , a chamber  114 , a membrane  115 , an actuator  190 , and a nozzle  116 . 
     The reservoir  111  can contain ink and supply the ink to the chamber  114  through the restrictor  113 , which will be described below. The reservoir  111  can receive ink from the outside of the inkjet head  100  through an inlet  112 . The inlet  112  and the chamber  114  can be formed on a third plate  30 , and the reservoir  111  can be formed or, a second plate  20 . 
     The restrictor  113  can connect the reservoir  111  and the chamber  114 , which will be described below, and function as a channel supplying the ink from the reservoir  111  to the chamber  114 . The restrictor  113  and the reservoir  111  can be formed on the second plate  20 . 
     The restrictor  113  can have a cross-section that is smaller than that of the reservoir  111 . When pressure is provided to the chamber  114  by the actuator  190 , the restrictor  113  can adjust the amount of the ink supplied from the reservoir  111  to the chamber  114 . 
     One side of the chamber  114  can be connected to the restrictor  113 , and the other side can be connected to the nozzle  116 . The chamber  114  can be formed inside the inkjet head  100  to receive ink, and the membrane  115  can cover the one side of the membrane  115 . 
     A plurality of inkjet heads can be formed in the widthwise direction inside the inkjet head  100 . Accordingly, a plurality of reservoirs  111  can be formed by being expanded in the widthwise direction, and each of the restrictors  113  can be formed between each chamber  114  and the reservoir  111 . 
     The nozzles  116  can be connected to the other side of each chamber  114  and provide a path through which ink is discharged to the outside of the inkjet head  100 . The nozzle  116  can be formed on a first plate  10 . 
     The actuator  190  can be coupled to one side of the inkjet head  100 , corresponding to a position of the chamber  114 , which is an upper side of the membrane  115 . The actuator  190  can provide pressure to the chamber  114  by generating vibration and transferring the vibration to the chamber  114  through the membrane  115 . The membrane  115  can be formed on a fourth plate  40 . 
     An upper electrode (not shown) and a lower electrode (not shown) can be coupled to one side of the inkjet head  100  in order to supply voltage to the actuator  190 . 
     The above-described inkjet head  100 , including the nozzle  116 , the chamber  114 , the restrictor  113 , and the reservoir  111 , can be formed by stacking the first plate  10 , the second plate  20 , the third plate  30 , and the fourth plate  40 , on which each of the corresponding elements are formed. The first plate  10 , the second plate  20 , the third plate  30 , and the fourth plate  40  can be made of a silicon board. The method of manufacturing the inkjet head  100  in accordance with an embodiment of the present invention will be described below. 
       FIG. 3  is a flowchart showing an inkjet head manufacturing method in accordance with an embodiment of the present invention. As shown in  FIG. 3 , the method of manufacturing the inkjet head  100  in accordance with an embodiment of the present invention can include a process represented by S 100 , in which a sintered piezoelectric element  400  is adhered to one side of the inkjet head  100  that is adjacent to the chamber  114 ; a process represented by S 200 , in which the actuator  190  is formed by dicing the piezoelectric element, to correspond to a position of the chamber  114 ; and a process represented by S 300 , in which one side of the inkjet head  100  is etched such that a part of the piezoelectric element  400  remaining between the adjacent actuators  190  is removed. Accordingly, by removing a part of the piezoelectric element  400  that remains between the actuators  190  of the inkjet head  100 , it is possible to manufacture the inkjet head  100  having the thin actuator  190  that reduces the crosstalk. 
       FIG. 4  and  FIG. 5  are plan views showing an inkjet head in accordance with an embodiment of the present invention. As shown in  FIG. 4 , in the process represented by S 100 , the sintered piezoelectric element  400  can be adhered to one side of the inkjet head  100  adjacent to the chamber  114 . 
     The chamber  114  can be formed inside the inkjet head  100 . The sintered piezoelectric element  400  can be adhered to one side, which is an upper side, of the inkjet head  100  adjacent to the chamber  114 . 
     The sintered piezoelectric element  400  can have a bulk shape. The bulk-shaped piezoelectric element  400  can be adhered to the upper side of the inkjet head  100 , corresponding to the position of the chamber  114 . The piezoelectric element  400  can be adhered to the upper side of the inkjet head  100  by using, for example, an adhesive. 
     Next, in the process represented by S 200 , the actuators  190  can be formed by dicing the piezoelectric element  400  such that the piezoelectric element  190  remains between the actuators  190 , which are to be adjacently formed corresponding to the position of each of the chambers  114 , as shown in  FIG. 5 . As described above, the chambers  114  can be arranged side by side in the widthwise direction of the inkjet head  100 , and the dicing process can sever and divide the piezoelectric element  400  such that the actuator  190  is formed on each chamber  114 . 
       FIG. 6  is a front cross-sectional view showing an inkjet head in accordance with an embodiment of the present invention. As shown in  FIG. 6 , the dicing process can be performed one time to divide the piezoelectric element  400 , to thereby form the adjacent actuators  190 . This can prevent a wall-shaped part of the piezoelectric element  400  from remaining between the adjacent actuators  190 . 
     The dicing process can be also performed to be shallow enough not to server the piezoelectric element  400  completely. Accordingly, it is possible to minimize the stress on the fourth plate  40  in the process of completely severing the piezoelectric element  400 . 
       FIG. 7  and  FIG. 8  are front cross-sectional views showing part of an inkjet head in accordance with an embodiment of the present invention. Through the dicing process, the thickness of the piezoelectric element  400  remaining between the adjacent actuators  190  may be identical to that of the actuator  190 , which is to be removed through the etching as described below, as shown in  FIG. 7 . Accordingly, it is possible to remove a part of the piezoelectric element  400  remaining between the adjacent actuators  190  and simultaneously form the actuators having desired thicknesses. 
     Next, in the process represented by S 300 , one side of the inkjet head  100  can be etched such that a part of the piezoelectric element  400  remaining between the adjacent actuators  190  is removed. The etching process can be preformed by, for example, wet etching. The etching conditions can be adjusted such that the actuators  190  can be physically separated from one another by removing a part of the piezoelectric element  400  remaining between the adjacent actuators  190 . Various solutions capable of etching the piezoelectric element  400  can be used as the etchant. For example, it is possible to use a solution having the composition of 1BHF:2HCl:4NH4Cl:4H2O. 
     Accordingly, the method of manufacturing the inkjet head  100  in accordance with an embodiment of the present invention can separate the adjacent actuators  190  by complementing the limitations of the dicing process, which is a mechanical method, with the etching process, which is a chemical method. This can give no stress to the fourth plate  40  but can prevent the crosstalk from being generated, thereby improving the discharging property of the inkjet head  100 . 
     On the other hand, the etching process can be performed over the overall part of one side of the inkjet head  100 . The process of forming an additional etching resist on one side of the inkjet head  100  can be omitted. Accordingly, it is possible to remove a part of the piezoelectric element  400  remaining between the adjacent actuators  190  and simultaneously reduce the thickness of the actuator  190 . 
     As a result, it is possible to decrease the actuating voltage of the inkjet head  100  and improve the frequency property of the inkjet head  100  because the thin actuator  190  can be formed even though the sintered bulk-shaped piezoelectric element is used. 
     Hitherto, although some embodiments of the present invention have been shown and described for the above-described objects, it will be appreciated by any person of ordinary skill in the art that a large number of modifications, permutations and additions are possible within the principles and spirit of the invention, the scope of which shall be defined by the appended claims and their equivalents.