Abstract:
There is provided an inkjet print head having a stable filter structure. The inkjet print head includes a vibration substrate including a first filter formed therein; and a channel forming substrate including a second filter and a pressure chamber formed therein, the second filter being connected to the first filter.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2012-0140578 filed on Dec. 5, 2012, 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 print head, and more particularly, to an inkjet print head including a filter having a stable structure. 
         [0004]    2. Description of the Related Art 
         [0005]    An inkjet print head has been widely used commercially and industrially. In addition, as a range of usage of inkjet print heads has gradually expanded, performance of inkjet print heads has also gradually improved. 
         [0006]    For example, the inkjet print head may include a filter for filtering foreign objects contained ink. The above-mentioned filter is installed in a vibration substrate so as to remove foreign objects contained in ink supplied from an ink tank to the inkjet print head. 
         [0007]    However, as inkjet print heads have been thinned in recent times, it is difficult to form a filter in the inkjet print head (particularly, in a vibration substrate). 
         [0008]    Meanwhile, related art examples of inkjet print heads including filters formed therein are disclosed in Patent Documents 1 and 2. Here, Patent Document 1 discloses that a channel unit 30 is provided with a filter part 120, and Patent Document 2 discloses that an ink supply hole 130 is provided with a membrane filter structure 16. However, since the filter part 120 of the Patent Document 1 is formed in a punching process, it may be difficult to be applicable to a thinned inkjet print head, and since the filter structure 16 of Patent Document 2 may not have sufficient strength, it may be easily damaged by external impacts. 
         [0009]    Therefore, development of an inkjet print head that can be formed through a general manufacturing process for a general inkjet print head and that has a stable filter structure has been urgently demanded. 
       RELATED ART DOCUMENTS 
       [0000]    
       
         (Patent Document 1) JP2009-101643 A 
         (Patent Document 2) JP2005-178364 A 
       
     
       SUMMARY OF THE INVENTION 
       [0012]    An aspect of the present invention provides an inkjet print head including a filter having a stable structure, not easily damaged by external impacts. 
         [0013]    According to an aspect of the present invention, there is provided an inkjet print head, including: a vibration substrate including a first filter formed therein; and a channel forming substrate including a second filter and a pressure chamber formed therein, the second filter being connected to the first filter. 
         [0014]    The first filter and the second filter may have the same shape. 
         [0015]    The first filter may include a plurality of first grooves extended to be elongated in a first direction, and the second filter may include a plurality of second grooves extended to be elongated in a second direction. 
         [0016]    The plurality of first grooves and the plurality of second grooves may be disposed to intersect one another. 
         [0017]    The first filter may include a plurality of first holes having a first size, and the second filter may include a plurality of second holes having a second size. 
         [0018]    The vibration substrate may have a thickness of 1.3 μm or less. 
         [0019]    The inkjet print head may further include a nozzle forming substrate including a restrictor and a nozzle formed therein, wherein the restrictor may connect the first filter and the pressure chamber, and the nozzle may be connected to the pressure chamber. 
         [0020]    According to another aspect of the present invention, there is provided an inkjet print head, including: a vibration substrate including a first filter formed therein; a first channel forming substrate including a second filter formed therein, the second filter being connected to the first filter; and a second channel forming substrate including a third filter formed therein, the third filter being connected to the second filter. 
         [0021]    At least one pair of the first filter, the second filter, and the third filter may have the same shape. 
         [0022]    The first filter, the second filter, and the third filter may have different shapes from each other. 
         [0023]    The first filter may include a plurality of first grooves extended to be elongated in a first direction, and the second filter may include a plurality of second grooves extended to be elongated in a second direction. 
         [0024]    The plurality of first grooves and the plurality of second grooves may be disposed to intersect one another. 
         [0025]    The third filter may include a plurality of third grooves extended to be elongated in the first direction. 
         [0026]    The third filter may include a plurality of third grooves extended to be elongated in a third direction. 
         [0027]    The first filter may include a plurality of first holes having a first size, the second filter may include a plurality of second holes having a second size, and the third filter may include a plurality of third holes having a third size. 
         [0028]    The first holes, the second holes and the third holes may have different sizes. 
         [0029]    The vibration substrate may have a thickness of 1.3 μm or less. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    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: 
           [0031]      FIG. 1  is a partially cut-away perspective view showing an inkjet print head according to a first embodiment of the present invention; 
           [0032]      FIG. 2  is a plan view of a vibration substrate shown in  FIG. 1 ; 
           [0033]      FIG. 3  is a plan view of a channel forming substrate shown in  FIG. 1 ; 
           [0034]      FIG. 4  is a partially cut-away perspective view showing an inkjet print head according to a second embodiment of the present invention; 
           [0035]      FIG. 5  is a plan view of a vibration substrate shown in  FIG. 4 ; 
           [0036]      FIG. 6  is a plan view of a channel forming substrate shown in  FIG. 4 ; 
           [0037]      FIG. 7  is a partially cut-away perspective view showing an inkjet print head according to a third embodiment of the present invention; 
           [0038]      FIG. 8  is a plan view of a vibration substrate shown in  FIG. 7 ; 
           [0039]      FIG. 9  is a plan view of a channel forming substrate shown in  FIG. 7 ; 
           [0040]      FIG. 10  is a partially cut-away perspective view showing an inkjet print head according to a fourth embodiment of the present invention; 
           [0041]      FIG. 11  is a plan view of a vibration substrate shown in  FIG. 10 ; 
           [0042]      FIG. 12  is a plan view of a first channel forming substrate shown in  FIG. 10 ; 
           [0043]      FIG. 13  is a plan view of a second channel forming substrate shown in  FIG. 10 ; 
           [0044]      FIG. 14  is a partially cut-away perspective view showing an inkjet print head according to a fifth embodiment of the present invention; 
           [0045]      FIG. 15  is a plan view of a vibration substrate shown in  FIG. 14 ; 
           [0046]      FIG. 16  is a plan view of a first channel forming substrate shown in  FIG. 14 ; and 
           [0047]      FIG. 17  is a plan view of a second channel forming substrate shown in  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0048]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
         [0049]    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. 
         [0050]    In the drawings, the shapes and dimensions of components may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components. 
         [0051]      FIG. 1  is a partially cut-away perspective view showing an inkjet print head according to a first embodiment of the present invention,  FIG. 2  is a plan view of a vibration substrate shown in  FIG. 1 ,  FIG. 3  is a plan view of a channel forming substrate shown in  FIG. 1 ,  FIG. 4  is a partially cut-away perspective view showing an inkjet print head according to a second embodiment of the present invention,  FIG. 5  is a plan view of a vibration substrate shown in  FIG. 4 ,  FIG. 6  is a plan view of a channel forming substrate shown in  FIG. 4 ,  FIG. 7  is a partially cut-away perspective view showing an inkjet print head according to a third embodiment of the present invention,  FIG. 8  is a plan view of a vibration substrate shown in  FIG. 7 ,  FIG. 9  is a plan view of a channel forming substrate shown in  FIG. 7 ,  FIG. 10  is a partially cut-away perspective view showing an inkjet print head according to a fourth embodiment of the present invention,  FIG. 11  is a plan view of a vibration substrate shown in  FIG. 10 ,  FIG. 12  is a plan view of a channel forming substrate shown in  FIG. 10 ,  FIG. 13  is a plan view of a second channel forming substrate shown in  FIG. 10 ,  FIG. 14  is a partially cut-away perspective view showing an inkjet print head according to a fifth embodiment of the present invention,  FIG. 15  is a plan view of a vibration substrate shown in  FIG. 14 ,  FIG. 16  is a plan view of a first channel forming substrate shown in  FIG. 14 , and  FIG. 17  is a plan view of a second channel forming substrate shown in  FIG. 14 . 
         [0052]    An inkjet print head according to a first embodiment of the present invention will be described with reference to  FIGS. 1 through 3 . 
         [0053]    An inkjet print head  100  may include a nozzle forming substrate  110 , a channel forming substrate  120 , a vibration substrate  130 , and an actuator  140 . In addition, the inkjet print head  100  may further include a first filter  310  and a second filter  320 . Here, the nozzle forming substrate  110 , the channel forming substrate  120 , and the vibration substrate  130  may be sequentially stacked in a vertical direction (a Z axis direction based on  FIG. 1 ). 
         [0054]    The nozzle forming substrate  110  may be formed of a monocrystal silicon substrate. However, the nozzle forming substrate  110  may be formed of a silicon on insulator (SOI) substrate, as needed. In this case, the nozzle forming substrate  110  may be a stack structure in which a silicon substrate and a plurality of insulating members are stacked. 
         [0055]    The nozzle forming substrate  110  may be provided with a plurality of nozzles  210 . More specifically, the nozzle  210  may completely penetrate through the nozzle forming substrate  110  in a vertical direction. That is, the nozzle  210  may have a depth equal to or smaller than a thickness of the nozzle forming substrate  110 . The nozzle  210  may have the same cross-sectional diameter in a thickness direction of the nozzle forming substrate  110  as shown in  FIG. 1 . However, the nozzle  210  does not necessarily have the same cross-sectional diameter in the thickness direction of the nozzle forming substrate  110 . For example, the nozzle  210  may have a cross-sectional diameter, gradually reduced toward a lower surface of the nozzle forming substrate  110  from an upper surface thereof. The nozzles  210  formed as described above may be formed to be spaced apart from each other by an interval in one direction (an x-axis direction based on  FIG. 1 ) of the nozzle forming substrate  110 . 
         [0056]    The nozzle forming substrate  110  may be further provided with a restrictor  230  and a manifold  240 . The restrictor  230  may be formed at a predetermined depth and may be connected to a pressure chamber  220  as shown in  FIG. 1 . Meanwhile, although the present embodiment shows a case in which the restrictor  230  is formed in the nozzle forming substrate  110 , the restrictor  230  may be formed in the nozzle forming substrate  120 , as needed. 
         [0057]    The manifold  240  may be connected to the pressure chamber  220  through the restrictor  230 . The manifold  240  may be formed to be elongated in a length direction (an X axis direction based on  FIG. 1 ) of the channel forming substrate  120 . That is, the manifold  240  may be formed as a single body in the length direction of the channel forming substrate  120  to thereby be simultaneously connected to the plurality of pressure chambers  220 . Although not shown in the drawings, the manifold  240  may be connected to an ink supply tank. Therefore, ink in the ink supply tank may be supplied to the respective pressure chambers  220  through the manifold  240 . 
         [0058]    The channel forming substrate  120  may be formed of a monocrystal silicon substrate similar to the nozzle forming substrate  110 . However, the channel forming substrate  120  may be formed of a silicon on insulator (SOI) substrate, as needed. In this case, the channel forming substrate  120  may be a stack structure in which a silicon substrate and a plurality of insulating members are stacked. The channel forming substrate  120  configured as described above may be formed on one surface (an upper surface) of the nozzle forming substrate  110 . 
         [0059]    The channel forming substrate  120  may be provided with the pressure chamber  220  and the second filter  320 . 
         [0060]    The pressure chamber  220  may have a predetermined volume. More specifically, the pressure chamber  220  may have a volume equal to or greater than that of the ink which may be discharged by one time operation of the actuator  140 . Here, the former may be advantageous for discharging a fixed quantity of ink and the latter may be advantageous for continuously discharging ink from the inkjet print head  100 . 
         [0061]    The second filter  320  may be connected to the manifold  240  and may include a plurality of second holes. For example, the second filter  320  may include the plurality of second holes spaced apart from each other by a predetermined interval in a first direction (an X axis direction based on  FIG. 1 ) and a second direction (a Y axis direction based on  FIG. 1 ) of the channel forming substrate  120 . The second filter  320  configured as described above may remove or alleviate the amount of foreign objects contained in the ink. 
         [0062]    The vibration substrate  130  may be formed on the channel forming substrate  120 . More specifically, the vibration substrate  130  may be formed on one surface (an upper surface) of the channel forming substrate  120 . The vibration substrate  130  configured as described above may deliver driving force generated by the actuator  140  to the pressure chamber  220 . Meanwhile, the vibration substrate  130  may have a thickness (or a height) of 1.3 μm or less. As described above, in the case in which the thickness of the vibration substrate  130  is changed to 1.3 μm or less, even when the height of the actuator  140  becomes lower, the driving force of the actuator  140  may be efficiently delivered to the pressure chamber  220 . Therefore, the entire height of the inkjet print head  100  may be significantly decreased, whereby the miniaturization and the thinning of the inkjet print head  100  may be achieved. 
         [0063]    The vibration substrate  130  may be provided with the first filter  310 . Here, the first filter  310  may include a plurality of first holes. For example, the first filter  310  may include the plurality of first holes spaced apart from each other by a predetermined interval in a first direction (an X axis direction based on  FIG. 1 ) and a second direction (a Y axis direction based on  FIG. 1 ) of the vibration substrate  310 . The first filter  310  configured as described above may remove or alleviate the amount of foreign objects contained in the ink. 
         [0064]    The first filter  310  may be connected to the second filter  320 . Here, a size D1 of the hole included in the first filter  310  may be the same as a size D2 of the hole included in the second filter  320 . In addition, an interval S1 between the holes included in the first filter  310  may be the same as an interval S2 between the holes included in the second filter  320 . That is, the first filter  310  and the second filter  320  may have the same shape. Therefore, according to the present embodiment, even when the vibration substrate  130 , a base material of the first filter  310  has a thin thickness, the strength of the first filter  310  may be reinforced by the second filter  320  of the channel forming substrate  120 . 
         [0065]    The actuator  140  may be formed on the vibration substrate  130 . The actuator  140  may have a size corresponding to a length (a length in a Y axis direction) and a width (a length in an X axis direction) of the pressure chamber  220 . More specifically, a length of the actuator  140  may be the same as the length of the pressure chamber  220  and a width of the actuator  140  may be the same as the width of the pressure chamber  220 . However, in order to easily make connection between the actuator  140  and electrodes, the length and the width of the actuator  140  may be greater than the length and the width of the pressure chamber  220 . 
         [0066]    The actuator  140  may include a lower electrode, a piezoelectric element, and an upper electrode. The lower electrode may be formed on the vibration substrate  130 . The piezoelectric element may be formed on the lower electrode. More specifically, the piezoelectric element may be disposed to correspond to the pressure chamber  220 . Here, a length and a width of the piezoelectric element may be the same as or greater than the length and the width of the pressure chamber. The upper electrode may be formed on the piezoelectric element. Here, a size of the upper electrode may be the same as or smaller than a size of the piezoelectric element. The actuator  140  configured as described above may generate driving force by deforming the piezoelectric element through a current signal supplied through the lower electrode and the upper electrode. 
         [0067]    Since the inkjet print head  100  configured as described above has a structure in which the first filter  310  and the second filter  320  are connected to each other, the strength of the filters  310  and  320  may be sufficiently ensured, even when the thickness of the vibration substrate  130  and the thickness of the channel forming substrate  120  are significantly decreased. Therefore, a phenomenon in which the filters  310  and  320  are damaged by an external impact or excessive vibrations of the vibration substrate  130  may be significantly decreased. 
         [0068]    Hereinafter, other embodiments of the present invention will be described. For reference, in a description of the following embodiments, the same reference numerals will be used to describe the same components as those of the first embodiment and a detailed description of these components will be omitted. 
         [0069]    An inkjet print head according to a second embodiment of the present invention will be described with reference to  FIGS. 4 through 6 . 
         [0070]    The inkjet print head  100  according to the present embodiment may be different from the inkjet print head  100  of the above-described embodiment in terms of configurations of the first filter  310  and the second filter  320 . 
         [0071]    In the present embodiment, the first filter  310  and the second filter  320  may have different sizes and arrangements. For example, the first filter  310  may include a plurality of first holes having a first size D1 as shown in  FIG. 5 . Here, the first holes may be arranged in a plurality of rows (based on an X-Y plane) according to the size D1 and a size of an ink inlet (not shown) and an interval between the first holes may be a first interval S1. 
         [0072]    Unlike this, the second filter  320  may include a plurality of second holes having a second size D2, smaller than the first size D1 as shown in  FIG. 6 . Here, the second holes may be arranged in a plurality of rows (based on an X-Y plane) according to the size D2 and the size of the ink inlet (not shown) and an interval between the second holes may be a second interval S2, smaller than the first interval  51 . Meanwhile, the first size D1 and the first interval S1 of the first holes included in the first filter  310  may be determined such that the first holes partially intersect the second holes included in the second filter  320 . 
         [0073]    The inkjet print head  100  configured as described above may maximize an effect of removing the foreign objects by the first filter  310  and the second filter  320 . In addition, since the inkjet print head  100  according to the present embodiment has a structure in which the first filter  310  and the second filter  320  partially intersect each other to be supported by each other, a phenomenon in which the first filter  310  is damaged may be alleviated even when the thickness of the vibration substrate  130  is decreased. 
         [0074]    An inkjet print head according to a third embodiment of the present invention will be described with reference to  FIGS. 7 and 9 . 
         [0075]    The inkjet print head  100  according to the present embodiment may be different from the inkjet print head  100  of the above-described embodiments in terms of shapes of the first filter  310  and the second filter  320 . 
         [0076]    In the present embodiment, the first filter  310  may include first grooves extended to be elongated in an X axis direction as shown in  FIG. 8 . The first grooves may be grooves each having a roughly rectangular shape having a first length L1 and a first width W1, and may be arranged at a predetermined interval in the X axis direction. Here, a first interval between the first grooves may be S1. 
         [0077]    Unlike this, the second filter  320  may include second grooves extended to be elongated in a Y axis direction as shown in  FIG. 9 . The second grooves may be grooves each having a roughly rectangular shape having a second length L2 and a second width W2, and may be arranged at a predetermined interval in the X axis direction. Here, a second interval between the second grooves may be S2. 
         [0078]    The inkjet print head  100  configured as described above include the first filter  310  and the second filter  320  having the rectangular shape, whereby the filters may be easily processed. 
         [0079]    An inkjet print head according to a fourth embodiment of the present invention will be described with reference to  FIGS. 10 through 13 . 
         [0080]    The inkjet print head  100  according to the present embodiment may be different from the inkjet print head  100  of the above-described embodiments, in that the inkjet print head  100  includes three filters  310 ,  320 , and  330 . To this end, the channel forming substrate  120  may include a first channel forming substrate  122  and a second channel forming substrate  124 . More specifically, the first filter  310  may be formed in the vibration substrate  130 , the second filter  320  may be formed in the second channel forming substrate  124 , and the third filter  330  may be formed in the first channel forming substrate  122 . 
         [0081]    Here, a size D1 of a first hole included in the first filter  310  and a first interval S1 between the first holes, a size D2 of a second hole included in the second filter  320  and a second interval S2 between the second holes, and a size D3 of a third hole included in the third filter  330  and a third interval S3 between the third holes may be different from one another. 
         [0082]    For reference, the first hole may be greater than the second hole and the third hole, and the second hole may be greater than the third hole in the accompanying drawings. In addition, the first interval S1 may be greater than the second interval S2 and the third interval S3, and the second interval S2 may be greater than the third interval S3. However, since this is merely an exemplary form, this may be changed to different configurations. 
         [0083]    An inkjet print head according to a fifth embodiment of the present invention will be described with reference to  FIGS. 14 through 17 . 
         [0084]    The inkjet print head  100  according to the present embodiment may be different from the inkjet print head  100  of the fourth embodiment in terms of shapes of the filters  310 ,  320 , and  330 . More specifically, the filters  310 ,  320 , and  330  may have a groove shape extended to be elongated in one direction. Here, a size (a length L1 and a width W1) and an interval of first grooves included in the first filter  310  may be the same as those of the first grooves according to the third embodiment, and a size (a length L2 and a width W2) and an interval of second grooves included in the second filter  320  may be the same as those of the second grooves according to the third embodiment. 
         [0085]    Meanwhile, third grooves included in the third filter  330  may have a rectangular shape extended in the same direction (an X axis direction) as that of the first grooves. Further, the third grooves may extend to be elongated in a third direction (for example, a diagonal direction). However, a size (a length L3 and a width W3) and an interval of the third grooves may be substantially the same as those of the second grooves. 
         [0086]    The inkjet print head  100  configured as described above according to the fourth and fifth embodiments may have the three filters  310 ,  320 , and  330  disposed to intersect one another, whereby the effect of removing foreign objects by the filters may be maximized. In addition, since portions of the filters  310 ,  320 , and  330  are supported by the filter positioned at a lower portion of the inkjet print head, the strength of the portions of the filters  310 ,  320 , and  330  may be improved. 
         [0087]    Therefore, according to the present embodiment, the thicknesses of the vibration substrate  130  and the channel forming substrates  120 ,  122 , and  124  may be significantly decreased, whereby the thinning of the inkjet print head  100  may be effectively achieved. 
         [0088]    As set forth above, since the strength of the filters may be improved, a phenomenon in which the filters are damaged or deformed by external impacts may be alleviated. 
         [0089]    Further, since the present invention is not restricted by formation of the filters, the inkjet print head may be thinned. 
         [0090]    While the present invention has been shown and described in connection with the 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.