Abstract:
A nozzle plate, inkjet printhead with the same and method of manufacturing the same. The nozzle plate includes at least one nozzle and has at least one heater segment disposed adjacent to the nozzle. The heater segment is configured to heat a first fraction of the circumference to a greater degree than a second fraction of the circumference. Heater segments are disposed at intervals around a circumference of the nozzle and are independently operable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an inkjet printhead. More particularly, the present invention relates to an inkjet printhead with a nozzle plate designed to control an ejecting direction of ink droplets ejected through a nozzle. The present invention further relates to a method of manufacturing such a nozzle plate. 
     2. Description of the Related Art 
     Generally, an inkjet printhead is a device for printing a color image on a surface of an object by ejecting droplets of ink on a desired location of the object. Such an inkjet printhead may be classified, according to an ink ejecting method, into a thermal inkjet printhead and a piezoelectric inkjet printhead. 
     In the thermal inkjet printhead, ink is quickly heated by a heater, formed of a heating element, when a pulse-type current is applied to the heater. As the ink is heated, the ink is boiled to generate bubbles. The bubbles expand and apply pressure to ink in a pressure chamber, thereby ejecting ink out of the pressure chamber through a nozzle in the form of droplets. However, the thermal inkjet printhead has to heat the ink to a high temperature, e.g., several hundred degrees Celsius or more, to generate bubbles, thereby resulting in high energy consumption and thermal stress therein. Also, it is hard to increase the driving frequency of the thermal inkjet printhead because the heated ink does not readily cool down. 
     In the piezoelectric inkjet printhead, a piezoelectric material is used. A shape transformation of the piezoelectric material generates pressure, thereby ejecting the ink out of a pressure chamber. 
       FIG. 1  shows a typical piezoelectric inkjet printhead. Referring to  FIG. 1 , a passage plate  10  is provided with an ink passage including a manifold  13 , a plurality of restrictors  12  and a plurality of pressure chambers  11 . A nozzle plate  20  is provided with a plurality of nozzles  22  corresponding to the plurality of pressure chambers  11 . A piezoelectric actuator  40  is disposed on the passage plate  10 . The manifold  13  functions to dispense the ink from an ink storage region (not shown) to the plurality of pressure chambers  11 . The restrictor  12  functions as a passage through which the ink is introduced from the manifold  13  to the pressure chamber  11 . The plurality of the pressure chambers  11 , which store ink to be ejected, are arranged on one or both sides of the manifold  13 . The plurality of pressure chambers  11  vary in their volumes as the piezoelectric actuator  40  is driven, thereby generating pressure variations to eject ink through the nozzles and suck ink from the manifold. To realize this, a portion of the passage plate  10  which defines a top wall of each pressure chamber  11  is designed to function as a vibration plate  14  that is to be deformed by the piezoelectric actuator  40 . 
     The piezoelectric actuator  40  includes a lower electrode  41  disposed above the passage plate  10 , a piezoelectric layer  42  disposed on the lower electrode  41 , and an upper electrode  43  disposed on the piezoelectric layer  42 . Disposed between the lower electrode  41  and the passage plate  10  is an insulating layer  31 , e.g., a silicon oxide layer. The lower electrode  41  is formed all over the top surface of the insulating layer  31  to function as a common electrode. The piezoelectric layer  42  is formed on the lower electrode  41  and is located above the pressure chambers  11 . The upper electrode  43  is formed on the piezoelectric layer  42  to function as a driving electrode applying voltage to the piezoelectric layer  42 . 
     When an image is printed using the above-described typical inkjet printhead, the resolution of the image is affected by the number of nozzles per inch. Here, the number of nozzles per inch is represented by “Channel per Inch (CPI)” and the image resolution is represented by “Dot per Inch (DPI).” The improvement of the CPI in the typical inkjet printhead generally depends on improvements in materials processing technologies, actuator improvements, etc. However, the improvement of the CPI may not keep up with demands for increasingly higher resolution (DPI) images. Therefore, a variety of technologies for printing a higher DPI image using a low CPI printhead have been developed.  FIGS. 2 and 3  show examples of those technologies. 
     According to one example, depicted in the upper portion of  FIG. 2 , a plurality of nozzles  51  and  52  are arranged along two or more rows. As illustrated, the nozzles  51  arranged along a first row and the nozzles  52  arranged along a second row may be staggered. Using this array of nozzles  51  and  52 , the droplets ejected from the nozzles  51  and  52  print an image, while forming a single line, as depicted in the lower portion of  FIG. 2 . That is, dots  61  formed by the nozzles  51 , which are arranged along the first row, and the dots  62  formed by the nozzles  52 , which are arranged along the second row, alternate on a print medium  60 . Therefore, the image DPI formed on the print medium  60  is two times the CPI of the printhead  50 . 
     However, in order to precisely print the image, the nozzles  51  and  52  must be arranged accurately along the respective rows. Therefore, there is a need for an arrangement system that can precisely arrange the nozzles  51  and  52 . This increases the size and cost of the printhead. 
     According to another example, depicted in  FIG. 3 , the printing is performed by a printhead  70  having a low CPI and inclined at a predetermined angle Θ with respect to a print medium  80 . That is, the printhead  70  is not perpendicular to a direction of travel of the print medium  80 , but rather is rotated from the perpendicular by the angle Θ. As a result, intervals between dots  81  formed on the print medium  80  are less than intervals between the nozzles  71  along the printhead  70 . Thus, the image DPI on the print medium  80  is higher than the CPI of the printhead  70 . In this case, the greater the inclined angle Θ, the higher the DPI. However, inclining the printhead  70  foreshortens the effective coverage of the printhead  70  on the print medium  80 . That is, the printing area is reduced such that, in order to obtain a printing area equal to that obtained by an uninclined printhead, the length of the printhead  70  must be increased. 
     SUMMARY OF THE INVENTION 
     The present invention is therefore directed to an inkjet printhead with a nozzle plate that is designed to control an ejecting direction of ink droplets ejected through a nozzle and a method of manufacturing such a nozzle plate, which substantially overcome one or more of the problems due to the limitations and disadvantages of the related art. 
     It is therefore a feature of an embodiment of the present invention to provide an inkjet printhead with a nozzle plate that includes a heater designed to control an ejecting direction of droplets of ink ejected through a nozzle, thereby printing a high resolution image. 
     It is therefore another feature of an embodiment of the present invention to provide a nozzle plate including a heater to partially change a surface tension of fluid in the nozzle by partially heating the fluid. 
     At least one of the above and other features and advantages of the present invention may be realized by providing a nozzle plate with at least one nozzle, the nozzle plate including at least one heater segment disposed adjacent to the nozzle. 
     The nozzle has a circumference and the heater segment may be configured to heat a first fraction of the circumference to a greater degree than a second fraction of the circumference. The nozzle plate may include at least two heater segments disposed at intervals around a circumference of the nozzle, each of the at least two segments being independently operable. The nozzle plate may include four segments disposed at 90 degree intervals around the circumference of the nozzle. 
     The nozzle plate may further include a substrate defining the nozzle and on which the heater segments are formed, electrodes that are electrically coupled to the heater segments, and an insulating layer formed on the substrate and covering the heater segments and the electrodes. The substrate may be formed of a base substrate for a printed circuit board. The heater segments may be formed of a material chosen from the group consisting of TaAl and TaN. The insulating layer may be formed of photo solder resist. 
     At least one of the above and other features and advantages of the present invention may also be realized by providing an inkjet printhead including a passage plate including an ink passage having a plurality of pressure chambers, a piezoelectric actuator formed on a surface the passage plate, and a nozzle plate formed on a surface of the passage plate and defining a plurality of nozzles coupled to corresponding ones of the plurality of pressure chambers, wherein the nozzle plate includes at least one heater segment disposed adjacent to each of the plurality of nozzles. 
     The nozzle plate may include at least two heater segments disposed at intervals around a circumference of the nozzle, each of the at least two segments being independently operable. The nozzle plate may include four segments disposed at 90 degree intervals around the circumference of the nozzle. 
     The nozzle plate may further include a substrate defining the plurality of nozzles and on which the heater segments are formed, electrodes that are electrically coupled to the heater segments, and an insulating layer formed on the substrate and covering the heater segments and the electrodes. The substrate may be formed of a base substrate for a printed circuit board. The heater segments may be formed of a material chosen from the group consisting of TaAl and TaN. The insulating layer may be formed of photo solder resist. 
     At least one of the above and other features and advantages of the present invention may further be realized by providing a method of manufacturing a nozzle plate having at least one nozzle, including forming an electrode on a substrate, forming a first insulating layer on the substrate to cover the electrode, patterning the first insulating layer to form a trench around a region in which the nozzle is to be formed, the trench partially exposing the electrode, depositing a resistive heating material in the trench to form a heater, forming a second insulating layer on the first insulating layer to cover the heater, and defining the nozzle inside the heater, the nozzle formed through the substrate, the first insulating layer and the second insulating layer. 
     The substrate may be formed of a base substrate for a printed circuit board. The heater may be divided into at least two segments that are arranged around the nozzle with a predetermined distance from the nozzle. The trench may be formed in the shape of an arc such that the heater does not completely encircle the nozzle and may be disposed proximate to the nozzle, such that heat generated by the heater heats one side of the nozzle preferentially. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
         FIG. 1  illustrates a schematic sectional view of a conventional inkjet printhead; 
         FIGS. 2 and 3  illustrate schematic views of examples of technologies for printing a higher DPI image using a low CPI printhead; 
         FIG. 4  illustrates a schematic vertical sectional view of an inkjet printhead according to an embodiment of the present invention; 
         FIG. 5A  illustrates an enlarged partial plan view of a heater that is provided on a nozzle plate according to an embodiment of the present invention; 
         FIG. 5B  illustrates an enlarged partial plan view of a heater that is provided on a nozzle plate according to another embodiment of the present invention; 
         FIGS. 6A-6C  illustrate sectional views of a deflection of ink droplets by a nozzle plate according to the present invention; 
         FIG. 7  illustrates a schematic view of a method of printing a higher resolution image using a nozzle plate of an inkjet printhead according to the present invention; and 
         FIGS. 8A-8F  illustrate sectional views of stages in a method of manufacturing a nozzle plate according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Korean Patent Application No. 10-2004-0087038, filed on Oct. 29, 2004, in the Korean Intellectual Property Office, and entitled: “Nozzle Plate Unit, Inkjet Printhead with the Same and Method of Manufacturing the Same,” is incorporated by reference herein in its entirety. 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in different forms and should not be construed as 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. In the figures, the dimensions of layers and regions are exaggerated for clarity of illustration. It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     According to embodiments of the present invention, the direction of ink droplets ejected through a nozzle may be controlled by adjusting the surface tension of ink in the nozzle using a heater, such that a high resolution image can be printed using a printhead having a relatively low CPI. 
     The heater of the printhead may only heat the ink to a degree sufficient to change the surface tension of the ink, such that it consumes less power than a heater of a conventional thermal inkjet printhead. For example, the surface tension of the ink may be sufficiently changed by increasing the temperature of the ink by several tens of degrees Celsius. 
     The nozzle plate may be formed of a printed circuit board (PCB) base substrate to reduce manufacturing costs. 
     While the description provided herein provides a detailed description in the context of a piezoelectric inkjet printhead that ejects ink, it will be understood that the present invention may be suitable applied to a variety of other fluids and fluid ejecting systems. 
       FIG. 4  illustrates a schematic vertical sectional view of an inkjet printhead according to an embodiment of the present invention and  FIG. 5A  illustrates an enlarged partial plan view of a heater that is provided on a nozzle plate according to an embodiment of the present invention. Referring to  FIGS. 4 and 5A , an inkjet printhead according to an embodiment of the present invention may include a passage plate  200  provided with an ink passage having a plurality of pressure chambers  204  and a piezoelectric actuator  300  disposed on a top surface of the passage plate  200  to apply a driving force for ejecting ink to the pressure chambers  204 . The inkjet printhead may also include a nozzle plate  100  attached on a bottom surface of the passage plate  200  and provided with a plurality of penetration nozzles  150  to eject the ink out of the pressure chambers  204 . 
     The ink passage may include, in addition to the plurality of pressure chambers  204 , a manifold  202  functioning as a common passage supplying ink, which is introduced from an ink inlet (not shown), to the pressure chambers  204 . The ink passage may also include a restrictor  203  functioning as an individual passage supplying ink from the manifold  202  to each pressure chamber  204 . A damper  205  may be disposed between the pressure chamber  204  and the nozzle  150  to concentrate energy, which is generated in the pressure chamber by the piezoelectric actuator  300 , on the nozzle  150  and to buffer sudden pressure variations. The elements defining the ink passage may be formed on the passage plate  200 . Some portion of the passage plate  200  may define a top wall of the pressure chamber  204  and function as a vibration plate when the piezoelectric actuator  300  operates. 
     Specifically, as shown in  FIG. 4 , the passage plate  200  may further include first and second passage plates  210  and  220 . The pressure chambers  204  may be formed on a bottom surface of the first passage plate  210  at a predetermined depth. The pressure chamber  204  may be formed in a rectangular shape having a longitudinal direction corresponding to the direction of ink flow between the manifold  202  and the nozzle  150 . 
     The manifold  202  may be formed on the second passage plate  220 . As shown in  FIG. 4 , the manifold  202  may be formed on a top surface of the second passage plate  220  at a predetermined depth. The manifold  202  may also be formed vertically penetrating the second passage plate  220  (this example is not shown). The restrictor  203  may be formed on the top surface of the second passage plate  220  at a predetermined depth to connect the manifold  202  to a first end of the pressure chamber  204 . The restrictor  203  may be also formed vertically penetrating the second passage plate  220  (this example is not shown). The damper  205  may be formed vertically penetrating the second passage plate  220  and corresponding to a second end of the pressure chamber  204 , so as to connect the pressure chamber  204  to the nozzle  150 . 
     Although the elements constituting the ink passage are separately arranged on the two passage plates  210  and  220  in the above description, this is only an exemplary embodiment and a variety of other ink passages and configurations may be provided on the inkjet printhead. For example, the passage plate may be formed of a single plate, more than two plates, etc. Accordingly, the present invention is not limited to the specific examples described herein. 
     The piezoelectric actuator  300  may be provided on a top surface of the first passage plate  210  to provide a driving force for forcing ink out of the pressure chamber  204 . The piezoelectric actuator  300  may include a lower electrode  310  disposed on the top surface of the first passage plate  210 , to function as a common electrode, a piezoelectric layer  320  disposed on the lower electrode  310 , to be transformed by an applied voltage, and an upper electrode  330  disposed on the piezoelectric layer  320 , to function as a driving electrode. 
     In detail, an insulating layer  212  may be formed between the lower electrode  310  and the first passage plate  210 . The lower electrode  310  may be formed of a single conductive material layer applied on an overall top surface of the insulating layer  212 . Alternatively, the lower electrode  310  may be formed of a titanium (Ti) layer and a platinum (Pt) layer. The lower electrode  310  may function as a common electrode and as a diffusion barrier layer, which prevents inter-diffusion between the first passage plate  210  and the piezoelectric layer  320 . The piezoelectric layer  320  may be formed on the lower electrode  310  over the pressure chamber  204 . The piezoelectric layer  320  is transformed by a voltage applied thereto, such that a vibration plate, i.e., a top of the pressure chamber  204 , is elastically deformed. The piezoelectric layer  320  may be formed of a piezoelectric material, e.g., a lead zirconate titanate (PZT) ceramic material. The upper electrode  330  may be disposed on the piezoelectric layer  320  and function to apply a driving voltage to the piezoelectric layer  320 . 
     The nozzle plate  100  may be formed on the bottom of the second passage plate  220  and define a nozzle  150 . A nozzle  150  may be provided for each pressure chamber  204  and may communicate therewith by way of the damper  205 , such that nozzle plate  100  includes a plurality of nozzles  150 . The nozzle plate  100  may include a substrate  110  defining the nozzle  150 , which may be tapered as it approaches the exit end. The substrate  110  may be formed of, e.g., a silicon wafer or an inexpensive base substrate for a PCB. 
     The nozzle plate  100  may include a heater  140  around the nozzle  150 . In detail, each nozzle  150  may be provided with a heater  140  and an electrode  120  for operating the heater  140 . The heater  140  may be disposed around the nozzle  150 , i.e., each of the plurality of nozzles  150  may include a respective heater  140 . The heater may be made of resistive heating material, e.g., TaAl, TaN, etc. The heater  140  and electrode  120  may be formed on a bottom surface of the substrate  110  and an insulating layer  130  may be formed thereon to cover the heater  140  and the electrode  120 . 
     Referring to  FIG. 5A , the heater  140  may include two arc-shaped heater segments  141  and  142  that are disposed around the nozzle  150 . The two segments  141  and  142  may be located a predetermined distance from the nozzle  150 . The two segments  141  and  142  may be independently operated to apply heat to ink in the nozzle  150 . Accordingly, the surface tension of the heated ink may be varied such that droplets of ink can be ejected out of the nozzle  150  in a deflected direction. This deflection of the ink is described in greater detail herein. 
     The electrode  120  may be formed of a conductive material, e.g., a highly conductive metal such as copper (Cu), which may be advantageously combined with a PCB substrate. As shown in  FIG. 5A , the electrode  120  may be provided in the form of a pattern that is connected to each of the two segments  141  and  142 , such that the two segments  141  and  142  can be independently operated. The pattern of the electrode  120  is not limited to the shape or configuration illustrated in  FIG. 5A  and may have various shapes or configurations for connection with each of the two segments  141  and  142 . 
     The insulating layer  130  may cover the heater  140  and the electrode  120  to protect and insulate them. The insulating layer  130  may be, e.g., an insulating material such as a photo solder resist (PSR), which is widely used as a PCB insulating material. 
       FIG. 5B  illustrates an enlarged partial plan view of a heater that is provided on a nozzle plate according to another embodiment of the present invention. Referring to  FIG. 5B , a heater  240  may include four segments  241 ,  242 ,  243  and  244  that are arranged around the nozzle  150 , e.g., at a regular interval such as 90°. Each of the four segments  241 ,  242 ,  243  and  244  may be arc-shaped. An electrode  121  may be patterned for connection with each of the four segments  241 ,  242 ,  243  and  244 , such that the four segments  241 ,  242 ,  243  and  244  can be independently operated. The pattern of the electrode  121  is not limited to the shape or configuration illustrated in  FIG. 5B  and may be of various shapes and configurations suitable for connection with each of the four segments  241 ,  242 ,  243  and  244 . Further, the heater is not limited to the shapes and configurations illustrated in  FIGS. 5A and 5B  and may be divided into two or more segments, e.g., three, five or six segments may be provided. 
       FIGS. 6A-6C  illustrate sectional views of a deflection of ink droplets by a nozzle plate according to the present invention. In particular,  FIGS. 6A-6C  illustrate ink deflection by the nozzle plate with a two-segment heater, as depicted in  FIG. 5A . Referring to  FIG. 6A , when a current is not applied to first and second segments  141  and  142  of the heater  140 , the segments  141  and  142  are not heated and thus the temperature of the ink in the nozzle  150  is uniformly maintained. In this case, the contact angle of the ink does not vary around the inner wall of the nozzle  150 . Accordingly, a convex meniscus M is formed, as shown in  FIG. 6A . That is, the meniscus M is symmetric with respect to the first and second heater segments. When pressure is applied to ink in the nozzle  150 , e.g., by energizing the piezoelectric actuator  300 , the ink is ejected from the nozzle  150  in the form of droplets. In particular, since the meniscus M is symmetric, the ink droplets D are ejected straight out of the nozzle  150 . 
       FIG. 6B  illustrates a case where ink is deflected. Referring to  FIG. 6B , a current is applied to only the first segment  141  of the heater  140 . Thus, heat is generated by the first segment  141 , and ink adjacent to the first segment  141  is heated. However, ink that is not adjacent to the first segment  141  is not heated at all, or heated to a lesser degree. As a result, the viscosity and surface tension of the heated ink changes with respect to the ink that is not heated, or heated to a lesser degree. In particular, the viscosity and surface tension is reduced, changing the contact angle of the heated ink with the inner wall of the nozzle  150 . Therefore, a meniscus M is formed that is asymmetric relative to the heater segments  141  and  142 , as shown in  FIG. 6B . In this case, when pressure is applied to ink in the nozzle  150 , ink droplets are ejected from the nozzle  150  is deflected manner. That is, with respect to the arrangement illustrated in  FIG. 6B , the ink droplets are ejected with a deflection to the right. Of course, spatially relative terms such as “right” are intended for descriptive purposes only, and various configurations of the present invention may be provided to deflect ink droplets in various directions. 
     The surface tension of the ink may be changed with a small amount of heat, such that the heater  140  may consume less power than, e.g., a heater of the conventional thermal inkjet printhead. For example, the surface tension of ink may be sufficiently changed by increasing the temperature of the ink by several tens of degrees Celsius. 
     Referring to  FIG. 6C , when a current is applied to only the second segment  142 , heat is generated by the second segment  142  and thus the ink adjacent to the second segment  142  is heated. Therefore, a meniscus M is formed that is asymmetric with respect to the heater segments  141  and  142 , as shown in  FIG. 6C . In this case, when pressure is applied to ink in the nozzle  150 , ink droplets are ejected from the nozzle  150  and deflected to the left. 
     As described above, when a current is selectively applied to one of the segments  141  and  142  provided on the nozzle plate  100 , the ejecting direction of the ink droplets may be deflected rightward or leftward. When, as illustrated in  FIG. 5B , the heater  140  is divided into four segments  141 ,  142 ,  143  and  144 , the ejection of ink droplets through the nozzle  150  may be varied in a greater number of directions. 
       FIG. 7  illustrates a schematic view of a method of printing a higher resolution image using a nozzle plate of an inkjet printhead according to the present invention. Referring to  FIG. 7 , the plurality of nozzles  150  are arranged in the nozzle plate  100  at a predetermined CPI rate. When a current is selectively applied to the segments  141  and  142  of the heater  140  formed around the nozzle  150 , the direction of ejection of ink droplets from the nozzle  150  may be varied. 
     In detail, printed dots  401  may be printed directly in front of the nozzle  150 . That is, dots  401  may be printed by ink ejected straight from the nozzle  150 , without deflection. Printed dots  402  and  403  may be printed offset from the nozzle  150 . That is, dots  402  and  403  may be printed by ink that is deflected as it is ejected from the nozzle  150 . Where segments  141  and  142  are arranged to the left and right of the nozzle  150 , respectively, ink may be deflected so as to form a row of printed dots that are formed on a single line on a print medium  400 , the dots spaced at a predetermined interval. As a result, in the example illustrated in  FIG. 7 , the DPI of the image formed on the print medium  400  may be three times the CPI of the nozzle plate  100 . 
     Further, the nozzle plate  100  having the four-segment heater  140  depicted in  FIG. 5B  may be employed to eject the ink droplets in a greater variety of directions, allowing an image having a higher resolution to be printed using the nozzle plate  100  having a relatively low CPI. 
     A method of manufacturing the nozzle plate will be described hereinafter with reference to the accompanying drawings.  FIGS. 8A-8F  illustrate sectional views of stages in a method of manufacturing a nozzle plate according to the present invention. In these drawings, the nozzle plate is illustrated such that the completed unit is shown having the heater and electrode on the upper surface, though it will be appreciated that this is simply for ease of reference and does not limit the scope of the present invention. 
     Referring to  FIG. 8A , the substrate  110  is provided and the electrode  120  is formed on the substrate  110  in a predetermined pattern. In detail, as described above, the substrate  110  may be formed of a base substrate for the PCB and may include, e.g., polyamide. The electrode  120  may be formed of a conductive material, e.g., a highly conductive metal such as Cu. Thus, Cu may be deposited and etched in a predetermined pattern to form electrode  120 . 
     As illustrated in  FIG. 8B , a first insulating layer  131  may be formed on the substrate  110  to cover the electrode  120 , in order to protect and insulate the electrode  120 . The first insulating layer  131  may be formed over the entire substrate  110  using, e.g., PSR. 
     As illustrated in  FIG. 8C , the first insulating layer  131  may be patterned to form, e.g., a trench  133 , to thereby partially expose the electrode  120 . The patterning of the first insulating layer  131  may be achieved by well-known photolithography processes, e.g., exposing, developing, etc. The trench  133  may be formed around a region where the nozzle  150  (refer to  FIG. 8F ) is to be defined in a subsequent stage. The trench  133  may be divided into two or more regions. That is, two or more separate trenches  133  may be formed. 
     As illustrated in  FIG. 8D , the heater  140  may be formed in the trench  133  by depositing a resistive heating material therein, e.g. TaAl, TaN, etc. The heater  140  may be formed as two or more segments corresponding to the trenches  133 , such that discrete heater segments are formed. 
     As illustrated in  FIG. 8E , a second insulating layer  132  may be formed on the first insulating layer  131  to cover the heater  140 , in order to protect and insulate the heater  140 . As with the first insulating layer  131 , the second insulating layer  132  may be formed of, e.g., PSR. 
     As illustrated in  FIG. 8F , the nozzle  150  may be defined between the segments of the heater  140 , through the substrate  110 , the first insulating layer  131  and the second insulating layer  132 , by using, e.g., a laser beam or drill. 
     As described above, the nozzle plate  100  of the present invention can be formed using a PCB base substrate through a PCB manufacturing process. That is, the nozzle plate  100  can be formed through a simple process with low cost. 
     Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.