Abstract:
Provided are a nozzle plate of an inkjet printhead and a method of manufacturing the same. The nozzle plate includes: a substrate including a plurality of nozzles; and a plurality of first grooves formed on the surface of a substrate around the nozzles. In this structure, ink remaining on the surface of the nozzle plate can be efficiently removed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2007-0128271, filed on Dec. 11, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a nozzle plate of an inkjet printhead, and more particularly, to a nozzle plate including grooves formed around nozzles and a method of manufacturing the same. 
         [0004]    2. Description of the Related Art 
         [0005]    An inkjet printhead is an apparatus that ejects very small droplets of printing ink on a printing medium in a desired position to print an image in a predetermined color. Inkjet printheads may be largely classified into thermal inkjet printheads and piezoelectric inkjet printheads. The thermal inkjet printhead produces bubbles using a thermal source and ejects ink due to the expansive force of the bubbles. The piezoelectric inkjet printhead applies pressure generated by deforming a piezoelectric material to ink and ejects the ink due to the generated pressure. 
         [0006]    In an inkjet printhead, when ink pressed by a pressure chamber is ejected via a nozzle of a nozzle plate, ink may be hardened and more viscous due to evaporation of a solvent in a nozzle outlet, and the sticking of dust or the mixture of bubbles may occur, thereby resulting in ejection failures. In order to solve the ejection failures, the surface of the nozzle plate of the inkjet printhead is wiped using a blade. Also, when the nozzle is clogged with ink or ejection failures occur after the inkjet printhead is used over a long period, a suction process or a purging process is performed on the printhead. In this case, ink may flow out from the nozzle and remain on the surface of the nozzle plate and thus, the ink remaining on the surface of the nozzle plate should be removed using a wiper. However, a wiping process, which is performed periodically by bringing the wiper into contact with the nozzle, damages a thin hydrophobic layer coated on the surface of the nozzle plate, thereby detrimentally affecting the ejection performance of the printhead. Also, contaminant factors, such as particles, which are present around the nozzle, may be stuck into the nozzle during the wiping process, thereby causing ejection failures. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a nozzle plate of an inkjet printhead and a method of manufacturing the same, which can prevent a wiper from directly contacting a nozzle plate and easily remove ink remaining on the surface of the nozzle plate. Specifically, a path is formed on the nozzle plate so that ink remaining on the surface of the nozzle plate can move via the path during a purging process or a suction process. 
         [0008]    Also, the present invention provides a nozzle plate of an inkjet printhead and a method of manufacturing the same, which can prevent a hydrophobic layer coated on the surface of the nozzle plate from being damaged during a wiping process due to the clogging of a nozzle with particles or dust stuck to the nozzle plate or a wiper or a repeated wiping process. 
         [0009]    According to an aspect of the present invention, there is provided a nozzle plate of an inkjet printhead. The nozzle plate of the inkjet printhead includes: a substrate including a plurality of nozzles; and a plurality of first grooves formed on the surface of a substrate around the nozzles. 
         [0010]    The first groove may be formed to enclose the corresponding nozzle and extend from the nozzle on both sides of the substrate. Also, the nozzles may be arranged at regular intervals, and the first groove may be formed in a direction perpendicular to a direction in which the nozzles are arranged. 
         [0011]    Second grooves may be connected to the first grooves, respectively, and formed along both end portions of the first grooves in a direction parallel to the direction in which the nozzles are arranged. Inner walls of the first and second grooves may be coated with a hydrophilic material, and an outer surface of the substrate may be coated with a hydrophobic material except the first and second grooves. Also, inner walls of the nozzles may be coated with a hydrophobic material. The first and second grooves may be formed using a wet etching process or a dry etching process. 
         [0012]    The width of the first groove may increase or decrease towards both end portions of the first groove and away from the corresponding nozzle. Alternatively, the width of the first groove may be maintained constant from the corresponding nozzle to both end portions of the first groove. 
         [0013]    The width of the first groove may decrease or be constant in a depthwise direction from the surface of the substrate. 
         [0014]    According to another aspect of the present invention, there is provided a method of removing ink remaining on the surface of a nozzle plate of an inkjet printhead. The nozzle plate of the inkjet printhead includes: a substrate including a plurality of nozzles; a plurality of first grooves formed in the surface of a substrate around each of the nozzles; and second grooves may be formed in both end portions of the first grooves in a direction parallel to the nozzles and connected to the first grooves, respectively. The method includes: collecting ink remaining on the surface of the nozzle plate in the first groove formed around the nozzle; and draining ink from the first groove toward the second groove due to capillary attraction. 
         [0015]    In order to facilitate the collection of ink remaining on the surface of the nozzle plate in the first groove formed around the nozzle, the method may further include wiping the surface of the nozzle plate using a wiper. 
         [0016]    The method may further include applying a negative pressure to the nozzle plate or inclining the nozzle plate after collecting ink remaining on the surface of the nozzle plate in the first groove formed around the nozzle. 
         [0017]    According to yet another aspect of the present invention, there is provided a method of manufacturing a nozzle plate. The method includes: preparing a substrate having a damper formed in a first surface of the substrate; forming a first oxide layer on the entire surface of the substrate; forming first photoresist on a second surface of the substrate and patterning the first photoresist by etching to form a groove pattern in the first oxide layer; removing the first photoresist, forming second photoresist on the second surface of the substrate, and patterning the second photoresist to form a nozzle pattern in the first oxide layer by etching; etching a portion of the substrate exposed by the nozzle pattern to a predetermined depth to form an upper portion of the nozzle; and removing the second photoresist and etching a portion of the substrate exposed by the groove pattern and a portion of the substrate exposed by the upper portion of the nozzle at the same time to form a groove with a predetermined depth and a nozzle connected to the damper. 
         [0018]    After forming the groove and the nozzle, the method may further include: forming a second oxide layer on inner walls of the groove and the nozzle; laminating dry film resist (DFR) to cover the groove; coating a hydrophobic material on the surface of the substrate outside the nozzle; and inner walls of the nozzle and the damper and removing the DFR. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0020]      FIG. 1  is a plan view of a nozzle plate of an inkjet printhead according to an embodiment of the present invention; 
           [0021]      FIG. 2A  is a magnified view of the nozzle shown in  FIG. 1 ; 
           [0022]      FIG. 2B  is a cross-sectional view taken along a line A-A′ of  FIG. 2A ; 
           [0023]      FIG. 3A  is a plan view of a portion of a nozzle plate of an inkjet printhead according to another embodiment of the present invention; 
           [0024]      FIG. 3B  is a cross-sectional view taken along a line B-B′ of  FIG. 3A ; 
           [0025]      FIG. 4  is a plan view of a portion of a nozzle plate of an inkjet printhead according to another embodiment of the present invention; 
           [0026]      FIG. 5A  is a plan view of a portion of a nozzle plate of an inkjet printhead according to another embodiment of the present invention; 
           [0027]      FIG. 5B  is a cross-sectional view taken along a line C-C′ of  FIG. 5A ; 
           [0028]      FIG. 6  is a diagram illustrating a method of removing ink remaining on the surface of a nozzle plate without bringing a wiper into contact with the nozzle plate according to an embodiment of the present invention; 
           [0029]      FIG. 7  is a diagram illustrating a method of removing ink remaining on the surface of a nozzle plate according to another embodiment of the present invention; 
           [0030]      FIGS. 8A through 15A  are plan views illustrating a method of manufacturing a nozzle plate according to an embodiment of the present invention; and 
           [0031]      FIGS. 8B through 15B  are cross-sectional views corresponding to  FIGS. 8A through 15A , respectively. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The same reference numerals are used to denote the same elements throughout the specification. In the drawings, the thicknesses of components are exaggerated for clarity. 
         [0033]      FIG. 1  is a plan view of a nozzle plate  100  of an inkjet printhead according to an embodiment of the present invention,  FIG. 2A  is a magnified view of the nozzle shown in  FIG. 1 , and  FIG. 2B  is a cross-sectional view taken along a line A-A′ of  FIG. 2A . 
         [0034]    Referring to  FIGS. 1 ,  2 A, and  2 B, the nozzle plate  100  of the inkjet printhead includes a substrate  150 , which has a plurality of nozzles  110  and a plurality of first grooves  120  formed around the nozzles  110 . The substrate  150  may be, for example, a silicon substrate, but the present invention is not limited thereto. A plurality of nozzles  110  for ejecting ink may be formed at regular intervals in an upper portion of the substrate  150 , and a plurality of dampers  140  are formed in a lower portion of the substrate  150  and connected to the nozzles  110 , respectively. Each of the dampers  140  is an ink flow path that connects a pressure chamber (not shown) of the inkjet printhead with the corresponding nozzle  110 . 
         [0035]    The plurality of first grooves  120  are formed to a predetermined depth in the surface of the substrate  150  to correspond to the nozzles  110 . As shown in  FIG. 2A , the first groove  120  may be formed to enclose the corresponding nozzle  110  and extend on both sides of the substrate  150 . Also, the width of the first groove  120  may be maintained constant from the nozzle  110  to both end portions of the first groove  120  as shown in  FIG. 2A . Furthermore, the width of the first groove  120  may be maintained constant in a depthwise direction from the surface of the substrate  150  as shown in  FIG. 2B . In this case, the first groove  120  may be formed by dry etching the substrate  150 . Alternatively, the first groove  120  may be formed such that the width of the first groove  120  decreases in the depthwise direction from the surface of the substrate  150 . In this case, the first groove  120  may be formed by wet etching the substrate  150 . The first groove  120  functions to collect ink remaining on the surface of the nozzle plate  100 . The first groove  120  may be formed in a direction perpendicular to a direction in which the nozzles  110  are arranged. 
         [0036]    Second grooves  130  may be further formed along both end portions of the first grooves  120  and connected to the first grooves  120 , respectively. Ink collected in the first grooves  120  can be drained toward the second grooves  130  due to capillary attraction. The second grooves  130  may be formed in a direction parallel to the direction in which the nozzles  110  are arranged. 
         [0037]    A hydrophilic material layer, for example, an oxide layer  170 , may be further coated on the entire surface of the substrate  150 . For example, the oxide layer  170  may be a silicon oxide layer, but the present invention is not limited thereto. Also, a hydrophobic material layer  160  may be further coated on the entire surface of the oxide layer  170  except the first and second grooves  120  and  130 . Thus, inner walls of the first and second grooves  120  and  130  may be coated with the hydrophilic material layer, for example, the oxide layer  170 , and an outer surface of the substrate  150  and inner walls of the nozzle  110  and the damper  140  may be coated with a hydrophobic material layer except the first and second grooves  120  and  130 . 
         [0038]      FIG. 3A  is a plan view of a portion of a nozzle plate  200  of an inkjet printhead according to another embodiment of the present invention, and  FIG. 3B  is a cross-sectional view taken along a line B-B′ of  FIG. 3A . Hereinafter, differences between the previous embodiment and the current embodiment will be principally explained. 
         [0039]    Referring to  FIGS. 3A and 3B , a plurality of nozzles  210  and a plurality of dampers  240  are formed in a substrate  250 . A plurality of first grooves  220  are formed on the surface of the substrate  250  around the nozzles  210 . Also, second grooves  230  are formed on both sides of the substrate  250  and connected to the first grooves  220 , respectively. The first groove  220  may be formed such that the width of the first groove  220  increases towards both end portions of the first groove  220  and away from the corresponding nozzle  210 . Also, the width of the first groove  220  may be maintained constant in a depthwise direction from the surface of the substrate  250  as shown in  FIG. 3B . In this case, the first groove  220  may be formed by dry etching the substrate  250 . Alternatively, the first groove  220  may be formed such that the width of the first groove  220  decreases in a depthwise direction from the surface of the substrate  250 . In this case, the first groove  220  may be formed by wet etching the substrate  250 . Also, inner walls of the first and second grooves  220  and  230  may be coated with a hydrophilic material layer, for example, an oxide layer  270 , and an outer surface of the substrate  250  and inner walls of the nozzles  210  and the damper  240  may be coated with a hydrophobic material layer  260  except the first and second grooves  220  and  230 . 
         [0040]      FIG. 4  is a plan view of a portion of a nozzle plate  300  of an inkjet printhead according to another embodiment of the present invention. 
         [0041]    Referring to  FIG. 4 , a first groove  320  is formed on the surface of a substrate (not shown) around a nozzle  310  such that the width of the first groove  320  decreases towards both end portions of the first groove  320  and away from the nozzle  310 . Also, the first groove  320  is connected to second grooves  330 . In this case, the first groove  320  may be formed such that the width of the first groove  320  is constant or decreases in a depthwise direction from the surface of the substrate. 
         [0042]      FIG. 5A  is a plan view of a portion of a nozzle plate  400  of an inkjet printhead according to another embodiment of the present invention, and  FIG. 5B  is a cross-sectional view taken along a line C-C′ of  FIG. 5A . 
         [0043]    Referring to  FIGS. 5A and 5B , a plurality of nozzles  410  and a plurality of dampers  440  are formed in a substrate  450 , and a plurality of first grooves  420  are respectively formed on the surface of the substrate  450  around the nozzles  410 . Also, second grooves  430  are formed on both sides of the substrate  450  and connected to the first grooves  420 , respectively. As shown in  FIG. 5A , the first groove  420  may have a square shape to enclose the corresponding nozzle  410  and may extend on both sides of the nozzle  410  on the surface of the substrate  450 . In another embodiment, the first groove  420  may have one of various shapes other than the square shape to enclose the nozzle  410 . As shown in  FIG. 5A , the first groove  420  may be formed such that the width of the first groove  420  is maintained constant from the nozzle  510  to both end portions of the first groove  420 . However, the first groove  420  may be formed such that the width of the first groove  420  decreases or increases towards both the end portions of the first groove  420  and away from the nozzle  410 . Also, as shown in  FIG. 5B , the first groove  420  may be formed such that the width of the first groove  420  gradually decreases in a depthwise direction from the surface of the substrate  450 . In this case, the first groove  420  may be formed by wet etching the substrate  450 . Alternatively, the first groove  430  may be formed such that the width of the first groove  420  is maintained constant in the depthwise direction from the surface of the substrate  450 . In this case, the first groove  420  may be formed by dry etching the substrate  450 . Also, inner walls of the first and second grooves  420  and  430  may be coated with a hydrophilic material layer, for example, an oxide layer  470 , and an outer surface of the substrate  450  and inner walls of the nozzles  410  and the damper  440  may be coated with a hydrophobic material layer  460  except the first and second grooves  420  and  430 . 
         [0044]    In the above-described nozzle plates  100 ,  200 ,  300 , and  400  of the inkjet printheads, ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  is collected in the first grooves  120 ,  220 ,  320 , and  420  around the nozzles  110 ,  210 ,  310 , and  410  and drained toward the second grooves  130 ,  230 ,  330 , and  430  due to capillary attraction. 
         [0045]      FIG. 6  is a diagram illustrating a method of removing ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  without bringing a wiper  650  into contact with the nozzle plates  100 ,  200 ,  300 , and  400 , according to an embodiment of the present invention. 
         [0046]    When the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  are wiped using the wiper  650  as shown in  FIG. 6 , ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  can be collected more easily in the first grooves  120 ,  220 ,  320 , and  420  around the nozzles  110 ,  210 ,  310 , and  410 . 
         [0047]      FIG. 7  is a diagram illustrating a method of removing ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400 , according to another embodiment of the present invention. 
         [0048]    Referring to  FIG. 7 , ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  is collected in the first grooves  120 ,  220 ,  320 , and  420  around the nozzles  110 ,  210 ,  310 , and  410 . Thereafter, a negative pressure may be applied to the nozzle plates  100 ,  200 ,  300 , and  400  or the nozzle plates  100 ,  200 ,  300 , and  400  may be inclined, thereby facilitating the removal of the remaining ink. When inclining the nozzle plates  100 ,  200 ,  300 , and  400 , ink remaining on the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  can be collected in the first grooves  120 ,  220 ,  320 , and  420  because the inner walls of the first grooves  120 ,  220 ,  320 , and  420  and the second grooves  130 ,  230 ,  330 , and  430  are coated with the hydrophilic material layers, for example, the oxide layers  170 ,  270 , and  470  and the surfaces of the nozzle plates  100 ,  200 ,  300 , and  400  are coated with the hydrophobic material layers  160 ,  260 , and  460  except the first grooves  120 ,  220 ,  320 , and  420  and the second grooves  130 ,  230 ,  330 , and  430 . Thus, ink remaining in hydrophobic regions of the nozzle plates  100 ,  200 ,  300 , and  400  can be externally drained through the first grooves  120 ,  220 ,  320 , and  420  and the second grooves  130 ,  230 ,  330 , and  430 , which are hydrophilic regions. 
         [0049]    Hereinafter, a method of manufacturing a nozzle plate of an inkjet printhead according to an embodiment of the present invention will be described with reference to  FIGS. 8A through 15B . 
         [0050]      FIG. 8A  is a plan view for explaining formation of a groove pattern  570   a  in an oxide layer  570  formed on a substrate  550 , and  FIG. 8B  is a cross-sectional view taken along a line D-D′ of  FIG. 8A . 
         [0051]    Referring to  FIGS. 8A and 8B , initially, the substrate  550  under which a damper  540  is formed is prepared. The substrate  550  may be, for example, a silicon substrate, but the present invention is not limited thereto. Thereafter, the oxide layer  570  is formed on the entire surface of the substrate  550 . The oxide layer  570  may be, for example, a silicon oxide layer. Thereafter, first photoresist  591  is coated on the oxide layer  570  formed on the top surface of the substrate  550 . The first photoresist  591  is patterned using exposure and developing processes. When the oxide layer  570  is etched using the patterned first photoresist  591  as an etch mask, the groove pattern  570   a  having a predetermined shape is formed in the oxide layer  570  to expose the substrate  550 . 
         [0052]    Referring to  FIGS. 9A and 9B , the first photoresist  591  is removed, and second photoresist  592  is coated on the oxide layer  570  formed on the top surface of the substrate  550  and patterned. When the oxide layer  570  is etched using the patterned second photoresist  592  as an etch mask, a nozzle pattern  570 b having a predetermined shape is formed in the oxide layer  570  to expose the substrate  550 . 
         [0053]    Referring to  FIGS. 10A and 10B , a portion of the substrate  550  exposed by the nozzle pattern  570   b  is etched to a predetermined depth, thereby forming a nozzle upper portion  510 ′. As a result, a portion of the substrate  550  disposed between the nozzle upper portion  510 ′ and the damper  540  has a thickness corresponding to the depth of a groove (refer to  520  in  FIG. 11B ) that will be formed in a subsequent process. 
         [0054]    Referring to  FIGS. 11A and 11B , the second photoresist  592  is removed, and a portion of the substrate  550  exposed by the groove pattern  570   a  and a portion of the substrate  550  exposed by the nozzle upper portion  510 ′ are etched at the same time. As a result, a nozzle  510  is formed in an upper portion of the substrate  550  and connected to the damper  540 , and a groove  520  having a predetermined depth is formed around the nozzle  510 . 
         [0055]    Meanwhile, the above-described method of manufacturing the nozzle plate according to the present invention may further include the following processes after forming the nozzle  510  and the groove  520 . 
         [0056]    Referring to  FIGS. 12A and 12B , an oxide layer  570  is formed on inner walls of the nozzle  510  and the groove  520 . As described above, the oxide layer  570  may be a silicon oxide layer. 
         [0057]    Referring to  FIGS. 13A and 13B , a dry film resist (DFR)  580  is laminated on the enter surface of the substrate  550  having the nozzle  510  and the groove  520 . Thereafter, the DFR  580  is patterned and left only on the groove  520 . Thus, the patterned DFR  580  has a shape corresponding to the groove  520 . 
         [0058]    Referring to  FIGS. 14A and 14B , a hydrophobic material layer  560  is coated on the entire surface of the oxide layer  570 . 
         [0059]    Referring to  FIGS. 15A and 15B , the DFR  580  is removed from the groove  520 , thereby completing the nozzle plate  500  according to the present invention. As a result, the oxide layer  570  is coated on the inner wall of the groove  520 , and the hydrophobic material layer  560  is coated on an outer surface of the substrate  550  and inner walls of the nozzle  510  and the damper  540  except the groove  520 . 
         [0060]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.