Patent Publication Number: US-2011063368-A1

Title: Multi inkjet head package, inkjet recording apparatus using the same, and method of aligning the same in inkjet recording apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 10-2009-0088201 filed on Sep. 17, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a multi inkjet head package, an inkjet recording apparatus using the multi inkjet head package, and a method of aligning a multi inkjet head package in the inkjet recording apparatus. 
     2. Description of the Related Art 
     Generally, inkjet heads are structures that convert an electrical signal into physical force and allow ink to be discharged from a minute nozzle in a liquid droplet form. 
     Recently, inkjet printing technology has been applied to various industrial fields relating to electronic apparatuses, textures, and the like. Presently, in the process of manufacturing PCBs, LCDs, PDPs, and the like, inkjet printing technology is being applied as a method for overcoming limits in regard to precision and productivity. 
     Such an industrial inkjet recording apparatus uses a plurality of heads for improving productivity and has been developed into a multi-head printing system capable of implementing high levels of precision and high resolution. 
     The above-described multi-head printing systems can print a large area with high precision. However, since a plurality of inkjet head assemblies are individually installed and aligned in an inkjet recording apparatus, many problems occur. 
     In particular, in order to individually align a plurality of inkjet head assemblies in the inkjet recording apparatus within a range of error of several μm, each inkjet head assembly must be installed in an expensive alignment support stand that controls the inkjet head assembly in directions X, Y, Z and θ. Accordingly, there are problems in that the size and the complexity of the inkjet recording apparatus increase, and the manufacturing cost rides. 
     In addition, since a plurality of inkjet head assemblies are installed with high precision in the alignment support stands, a high level of caution needs to be paid to the attachment or detachment of the inkjet head assemblies, the supply of ink, and the like. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides a multi inkjet head package having high precision by preliminarily fixing inkjet head assemblies to a rack and aligning the inkjet head assemblies. 
     An aspect of the present invention also provides an inkjet recording apparatus which allows the multi inkjet head package to be aligned with high precision. 
     An aspect of the present invention also provides a method of aligning the multi inkjet head package in the inkjet recording apparatus. 
     According to an aspect of the invention, there is provided a multi inkjet head package including: a plurality of inkjet head assemblies each having a head plate in which an inkjet head discharging ink is housed; a rack in which the head plate is housed so as to expose the inkjet head; and a preliminary fixation portion that is installed on the rack and allows the head plate to be preliminarily fixed to the rack. 
     The rack may be configured to include a head plate housing portion of a height that is same as that of the head plate. 
     The head plate may extend to a side portion and includes a screw hole forming portion in which a screw hold is formed, and the head plate housing portion may have a screw hole formed in a position corresponding to the screw hole of the head plate on a side portion and a seat portion of the screw hole forming portion formed in a shape corresponding to the screw hole forming portion. 
     The screw hole forming portion and the seat portion may be configured to have rounding-processed end portions. 
     The preliminary fixation portion may include an elastic plate that presses a part of the head plate and a fixation pin that sets a movement range of the elastic plate. 
     An alignment mark may be formed in the rack, the head plate, or the rack and the head plate. 
     Head plates may be configured to be arranged on the rack in a single row. 
     The head plates may be arranged on the rack in an offset pattern. 
     The head plates may be consecutively tiltedly arranged on the rack. 
     According to another aspect of the present invention, there is provided an inkjet recording apparatus including: a multi inkjet head package that includes a preliminary fixation portion preliminarily fixing an inkjet head assembly and a rack in which an inkjet head of the inkjet head assembly is exposed; an alignment support stand that aligns the multi inkjet head package; and an alignment camera that recognizes an alignment mark formed in the multi inkjet head package. 
     The inkjet recording apparatus may further include a moving stage, on which a printing medium sits, allowing printing to be performed while the printing medium moves. In addition, the multi inkjet head package is fixed to the alignment support stand. 
     The inkjet recording apparatus may further include: a fixation stage on which the printing medium sits; and a movement support stand that allows printing to be performed while the multi inkjet head package moves on the fixation stage. 
     The preliminary fixation portion may be configured to include an elastic plate that presses a part of a head plate in which the inkjet head is housed and a fixation pin that sets a movement range of the elastic plate. 
     An alignment mark may be formed in the rack, the head plate, or the rack and the head plate. 
     According to another aspect of the present invention, there is provided a method of aligning a multi inkjet head. The method includes: installing a rack in an alignment support stand of an inkjet recording apparatus; disposing an inkjet head assembly in the rack and aligning the head assembly in a preliminarily fixed state by using the alignment support stand; and checking an alignment state by recognizing an alignment mark that is formed in the rack or the inkjet head assembly by using an alignment camera and fixing the inkjet head assembly to the rack. 
     The preliminary fixation may be configured to be performed by using an elastic plate that presses a part of a head plate that houses an inkjet head. 
     An alignment reference value of the inkjet head assembly may be set, and a next head assembly may be aligned by using the alignment reference value. 
     The method may further include aligning the rack after the installing of a rack in an alignment support stand. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a schematic perspective view of an inkjet recording apparatus according to an embodiment of the present invention; 
         FIG. 2  is a schematic perspective view of a multi inkjet head package according to an embodiment of the present invention; 
         FIG. 3  is an exploded perspective view illustrating the appearance of installing the inkjet head assembly shown in  FIG. 2  to a rack; 
         FIGS. 4A to 4F  are schematic perspective views illustrating steps in which an inkjet head assembly is installed in a rack so as to be aligned; 
         FIG. 5  is a schematic diagram illustrating the appearance of aligning an inkjet head assembly through a rack; 
         FIGS. 6A to 6C  are schematic diagrams showing the appearance of disposing inkjet head assemblies in a rack in various manners; 
         FIG. 7  is a flowchart showing the operations of aligning an inkjet head assembly according to an embodiment of the present invention in equipment through a rack; and 
         FIG. 8  is a schematic perspective view of an inkjet recording apparatus according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components. 
       FIG. 1  is a schematic perspective view of an inkjet recording apparatus according to an embodiment of the present invention. 
     As shown in  FIG. 1 , an inkjet recording apparatus  100  according to an embodiment of the present invention may be configured to include a multi inkjet head package  10 , an alignment support stand  140 , and an alignment camera  80 . 
     In the multi inkjet head package  10 , inkjet heads of a plurality of inkjet head assemblies are exposed and discharge ink onto a printing medium. 
     The multi inkjet head package  10  may include all the technical aspects described with reference to  FIGS. 2 to 6 . 
     Here, directions for aligning an inkjet head assembly  20  in the multi inkjet head package  10  are defined as follows. Of directions X, Y, Z, and θ as shown in  FIG. 1 , one of directions X and Y is a main scanning direction in which a printing medium moves, and the other of directions X and Y is a sub-scanning direction that is perpendicular to the main scanning direction. In addition, direction Z is a height direction in which the inkjet head assembly  20  is installed in a rack  40 , and direction θ is the direction of an angle formed by the inkjet head assembly  20  with respect to the horizontal surface of the rack  40 . 
     Hereinafter, the directions are simply denoted by directions X, Y, Z, and θ. 
     The alignment support stand  140  is delicately driven in directions X, Y, Z, and θ for aligning the rack  40  in directions X, Y, Z, and θ and aligning the inkjet head assembly  20 , which is disposed on the rack  40 , in directions X, Y, Z, and θ of the rack  40 . 
     In the multi inkjet head package  10 , an alignment mark (a shape such as a cross, a circle, or a rectangle) is formed, and the alignment mark can be recognized by the alignment camera  80 . 
     First, direction θ of the inkjet head assembly  20  is corrected on the horizontal plane of the rack  40  by using the alignment camera  80 , such that the rack  40  and the inkjet head assembly  20  are positioned to be at a same angle. Then, the rack  40  and the inkjet head assembly  20  are corrected such that the axes in directions X and Y thereof are parallel to each other. 
     Before being aligned, the inkjet head assembly  20  is preliminarily fixed to the rack  40 , so that a misalignment between the rack  40  and the inkjet head assembly  20  can be prevented. 
     In the inkjet recording apparatus  100  according to this embodiment, the multi inkjet head package  10  is provided in a state of being fixed to the alignment support stand. Here, printing is performed while a moving stage  130  on which a printing medium sits moves. 
     Hereinafter, the multi inkjet head package  10  will be described in detail with reference to  FIGS. 2 to 6 . 
       FIG. 2  is a schematic perspective view of a multi inkjet head package according to an embodiment of the present invention.  FIG. 3  is an exploded perspective view illustrating the appearance of installing the inkjet head assembly shown in  FIG. 2  to the rack. 
     As shown in  FIGS. 2 and 3 , the multi inkjet head package  10  according to an embodiment of the present invention may be configured to include a plurality of inkjet head assemblies  20 , a rack  40 , and preliminary fixation portions  42 . 
     The inkjet head assembly  20  is configured by a cartridge  22  that is supplied with ink and stores the ink therein, an inkjet head  26  that discharges the ink supplied from the cartridge  22  in a liquid droplet form, and a head plate  24  that houses the inkjet head  26 . 
     The head plate  24  is preliminary fixed to the rack  40  by the preliminary fixation portion  42  and then aligned. Then, the head plate  24  is fixed completely by a screw  28 . 
     The rack  40  houses the head plate  24  so as to allow the inkjet head  26  to be exposed. The rack  40  includes a head plate housing portion  44  having the same shape as that of the head plate  24  for housing the head plate  24 . 
     Here, the height of the head plate housing portion  44  may be configured to be equal to that of the head plate  24 . The head plate housing portion  44  may be configured by a head plate housing hole  448  that allows the front face of the head plate  24  to be exposed and a seat portion  446  on which a screw hole forming portion  224  of the head plate  24  sits. 
     The head plate  24  extends to the side portion and includes a screw hole forming portion  244  in which a screw hole  246  is formed. 
     As regards the configuration of the head plate  24 , the head plate housing portion  44  may have a side portion in which a screw hole  446  is formed in a position corresponding to the screw hole  246  of the head plate  24  and a seat portion  444  of the shape corresponding to the screw hole forming portion  244  is formed. 
     In other words, by disposing the screw hole forming portion  244  of the head plate  24  on the seat portion  444 , the inkjet head  26  of the head plate  24  can be exposed externally. 
     Here, as the embodiment shown in the figure, the screw hole forming portion  224  and the seat portion  444  may have rounding-processed end portions. 
     The preliminary fixation portion  42  is a device that presses the head plate  24  so as not to move in the head plate housing portion  44  after the head plate  24  is disposed in the head plate housing portion  44  of the rack  40  as described above. 
     The preliminary fixation portion  42  may be configured by an elastic plate  422  that presses a part of the head plate  24  and a fixation pin  44  that sets the movement range of the elastic plate  422 . 
     In the elastic plate  422 , a movement hole  426  in which the fixation pin  44  fits is formed. The length of the movement hole  426  sets the movement length of the elastic plate  422 . 
     In a case where the preliminary fixation is performed by the elastic plate  422 , a misalignment between the rack  40  and the inkjet head assembly  20 , which occurs in a case where the head plate is completely fixed by using the screw  28 , can be prevented. 
     The above-described elastic plate  422  can be manufactured together with the rack  40 . An elastic plate of a type that has sufficient rigidity to allowing separate installation and sufficient strength to withstand the rotary force of the screw is used as the elastic plate  422 . 
     After all of the inkjet head assemblies  20  are fixed to the rack  40 , an exterior cover is combined with the rack  40  so as to be manufactured in the state of a package. 
       FIGS. 4A to 4F  are schematic perspective views illustrating steps in which the inkjet head assembly is installed in the rack so as to be aligned. 
       FIGS. 4A to 4F  are illustrated on a premise that the rack  40  is installed in the alignment support stand  140  of the inkjet recording apparatus  100 . 
       FIG. 4A  illustrates the rack  40  that is provided in a state of being installed to the alignment support stand  140  (see  FIG. 1 ). The rack  40  is provided in a state in which the preliminary fixation portion  42  is open. Then, as illustrated in  FIG. 4B , the inkjet head assembly  20  is housed in the rack  40 , and, as illustrated in  FIG. 4C , the preliminary fixation portion  42  is set so as to press a part of the head plate  24  of the inkjet head assembly  20 . 
     Then, after being aligned in directions X, Y, Z, and θ by using a clamp  60  that is linked with the alignment support stand  140 , as shown in  FIG. 4D , the inkjet head assembly  20  is fixed by using the screw  28  as illustrated in  FIG. 4E . 
     Thereafter, as illustrated in  FIG. 4F , the clamp  60  is separated from the inkjet head assembly  20 , and the next inkjet head assembly  20  is fixed to the rack  40 . The above-described procedure is repeatedly performed. 
       FIG. 5  is a schematic diagram illustrating the appearance of aligning the inkjet head assembly through the rack. 
     As illustrated in  FIG. 5 , a method of aligning the rack  40  as illustrated in  FIG. 4D  in a state in which the rack  40  is installed in the alignment support stand  140  of the inkjet recording apparatus  100  can be understood. 
     In addition, an alignment mark  248  can be formed in the rack  40 , the head plate  24 , or the rack  40  and the head plate  24 . 
     The position of the alignment mark  248  is searched for after the alignment camera  80  is adjusted, and a deviation between an alignment reference portion  82  and the alignment mark  248  is acquired through a control unit  85 . Then, alignment of the rack  40  and the inkjet head assembly  20  in the directions of X, Y, Z, and θ is performed. 
       FIGS. 6A to 6C  are schematic diagrams showing the appearance of disposing the inkjet head assemblies in the rack in various manners. 
       FIG. 6A  illustrates an example in which the head plates  24  are arranged on the rack  40  in a single row.  FIG. 6B  illustrates an example in which the head plates  24  are arranged on the rack  40  in an offset pattern. In addition,  FIG. 6C  illustrates an example in which the head plates  24  are consecutively tiltedly arranged on the rack  40 . 
     The above-described modified examples are not limited to this embodiment and may be selected in various manners in accordance with the printing length. 
       FIG. 7  is a flowchart showing the operations of aligning the inkjet head assembly according to an embodiment of the present invention in equipment through the rack. 
     Hereinafter, a method of aligning a multi inkjet head according to an embodiment of the present invention will be described with reference to  FIG. 7 . First, the rack  40  is installed in the alignment support stand  140  of the inkjet recording apparatus  100  in operation S 10 . 
     Then, the inkjet head assembly  20  is disposed in the rack  40 . Then, the inkjet head assembly  20  is aligned in a preliminarily fixed state in operation S 30  by the alignment support stand  140  in operation S 40 . 
     At this moment, the alignment mark  248  that is formed in the rack  40  or the inkjet head assembly  20  is recognized so as to check the alignment state in operation S 50  by using the alignment camera  80 , and the inkjet head assembly  20  is fixed to the rack  40  by using the screw  28 . 
     The preliminary fixation is performed by using the preliminary fixation portion  42  of the above-described multi inkjet head package  10 , and thus a detailed description thereof will be omitted. 
     However, the rack  40  may be aligned before the inkjet recording apparatus  10  is aligned in operation S 20 . 
     After one inkjet head assembly is aligned, an alignment reference value at that moment is set, and the next inkjet head assembly can be aligned by using the alignment reference value in operation S 60 . 
       FIG. 8  is a schematic perspective view of an inkjet recording apparatus according to another embodiment of the present invention. 
     The inkjet recording apparatus  200  of this embodiment, similarly to the inkjet recording apparatus  100  illustrated in  FIG. 1 , may be configured to include a multi inkjet head package  10 , an alignment support stand  140 , and an alignment camera  80 . 
     However, in this embodiment, differently from the embodiment illustrated in  FIG. 1 , a printing medium is maintained in a state of sitting in a fixation stage  230 , and printing is performed while the multi inkjet head package  10  moves on the fixation stage  230 . 
     At this moment, the multi inkjet head package  10  can be moved by a movement support stand  260  that is disposed on an equipment base  220 . 
     On the other hand, all the technical aspects and the alignment methods of the multi inkjet head package  10  are also applied to the inkjet recording apparatus  200  illustrated in  FIG. 8 . Thus, a detailed description thereof will be omitted. 
     According to a multi inkjet head package, an inkjet recording apparatus using the multi inkjet head package, and a method of aligning a multi inkjet head package in the inkjet recording apparatus according to an embodiment of the present invention, an alignment process can be performed by using a single alignment support stand that controls a plurality of inkjet head assemblies in directions X, Y, Z, and θ through the rack. Therefore, the structure and the control process of the inkjet recording apparatus can be simplified. 
     In addition, the disposition direction of each inkjet head assembly can be changed in various manners by changing the design of the rack. Accordingly, the length of the printing head can be arbitrarily adjusted by a user. 
     In addition, multiple heads are manufactured as a single package by using the rack, and accordingly, the supply of the amount of flow and the pneumatic control line can be simplified. 
     In addition, one alignment support stand, which is expensive, controlling the inkjet head assembly in directions X, Y, Z, and θ is used. Accordingly, there are advantages in that the equipment manufacturing costs can be reduced, and embodiments of the present invention can be generally used for various equipment. 
     While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.