Patent Publication Number: US-8123340-B2

Title: Ink-jet printer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2008-0088209, filed with the Korean Intellectual Property Office on Sep. 8, 2008, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an inkjet printer. 
     2. Description of the Related Art 
     An inkjet printer performs printing by converting an electrical signal into a physical force and ejecting ink droplets through a nozzle. Recently, there has been an increase in the density and the number of nozzles formed in the inkjet printer, for the purpose of improving the print quality of the inkjet printer. 
     With the increased number of nozzles in the inkjet printer, the channel for supplying ink to each inkjet head becomes longer, causing a lengthwise pressure difference in the supply channel. 
     The pressure difference in the supply channel causes a pressure difference between the inkjet heads coupled to the supply channel and changes the jetting characteristic of each nozzle. Therefore, printing cannot be guaranteed to be uniform, deteriorating the performance of the inkjet printer. 
     SUMMARY 
     The present invention provides an inkjet printer having a uniform jetting characteristic among nozzles. 
     An aspect of the present invention features an inkjet printer. The inkjet printer in accordance with an embodiment of the present invention can include a supply channel coupled to a plurality of inkjet heads; a first main reservoir and a second main reservoir being coupled to either side of the supply channel; and a first press and a second press applying pressure to the inside of the first main reservoir and the second main reservoir, respectively. 
     Here, the supply channel can be extended lengthwise, and the plurality of inkjet heads can be coupled lengthwise to the supply channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an inkjet printer according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view showing an inkjet head according to an embodiment of the present invention. 
         FIGS. 3 and 4  are cross-sectional views showing ink-injection of an inkjet printer according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Some of the characteristics and advantages of the present invention will be apparent through the following drawings and detailed description. 
     Hereinafter, embodiments of an inkjet printer in accordance with the present invention will be described in detail with reference to the accompanying drawings. In description with reference to accompanying drawings, the same reference numerals will be assigned to the same or corresponding elements, and repetitive descriptions thereof will be omitted. 
       FIG. 1  is a perspective view showing an inkjet printer  100  according to an embodiment of the present invention. As shown in  FIG. 1 , an inkjet printer  100  according to an embodiment of the present invention includes a supply channel  130  coupled to a plurality of inkjet heads  150 , a first main reservoir  111  and a second main reservoir  112 , which are joined to either side of the supply channel  130  and a first press  121  and a second press  122 , which press the inside of the first main reservoir  111  and the second main reservoirs  112 , respectively, thereby improving the print quality by maintaining a uniform jetting characteristic among a multiple number of nozzles  145 . 
       FIG. 2  is a cross-sectional view showing an inkjet head  151  according to an embodiment of the present invention. As shown in  FIG. 2 , an inkjet head  151  can include a reservoir  142 , a restrictor  143 , a chamber  144 , a membrane  147 , an actuator  146  and a nozzle  145 . 
     The reservoir  142  accommodates ink and provides the ink to the chamber  144  through the restrictor  143 , which will be described below. The reservoir  142  can be supplied with the ink from the supply channel  130  through an inlet port  132 , which, as shown in  FIG. 1 , can be linked to the supply channel through a flow path formed inside a part  131  extended from one side of the supply channel  130 . 
     The reservoir  142  and the chamber  144  are linked to each other through the restrictor  143 , which can function as a channel for supplying the ink from the reservoir  142  to the chamber  144 . The restrictor  143  is formed to have a smaller cross sectional area than that of the reservoir  142 . As a result, if pressure is applied to the chamber  144  by the actuator  146 , it is possible to control the flow of the ink supplied from the reservoir  142  to the chamber  144 . 
     The chamber  144  is linked to the restrictor  143  and connected to the reservoir  142 . The chamber  144  is linked to the nozzle  145 . Through this structure, the inkjet head  151  is supplied with and accommodates the ink from the reservoir  142 . By supplying this ink again to the nozzle  145 , the ink can be ejected. 
     One surface of the chamber  144  is covered by the membrane  147 . The actuator  146  can be coupled to the upper surface of the membrane  147  that corresponds to the position of the chamber  144 . 
     The actuator  146  is coupled to the upper surface of the membrane that corresponds to the position of the chamber  144  and can generate vibration when electric power is supplied. The actuator  146  transfers the vibration to the membrane, thereby applying pressure to the chamber  144 . The actuator  146  can be implemented by various methods, such as a piezoelectric method or an electrostatic method. 
     The nozzle  145  is linked to the chamber  144  and is supplied with the ink from the chamber  144 , and then can perform the function of ejecting the ink. If the vibration generated by the actuator  146  is delivered to the chamber  144 , pressure is given to the chamber  144 , ejecting the ink through the nozzle  145 . 
     There can be a plurality of inkjet heads  150 . Each of the plurality of the inkjet heads  150  can be coupled lengthwise to the supply channel  130 , which is extended lengthwise. The supply channel  130  and the reservoir  142  of each inkjet head can be linked to each other through a connecting portion  141 . 
       FIGS. 3 and 4  are cross-sectional views showing ink-injection of an inkjet printer  100  according to an embodiment of the present invention. As shown in  FIG. 3 , the first main reservoir  111  and the second main reservoir  112  can be joined to either side of the supply channel  130 . The first main reservoir  111  can be linked to one side of the supply channel  130  through the inlet port  132 . The second main reservoir  112  can be linked to the other side of the supply channel  130  through an outlet port  134 . 
     The first main reservoir  111  can accommodate the ink that will be supplied to a plurality of inkjet heads  150 . The second main reservoir  112  can accommodate ink that remains after being supplied to the plurality of inkjet heads  150  through the supply channel  130 . Therefore, the second main reservoir  112  makes it easier to retrieve the residual ink. 
     The first press  121  and the second press  122  can press the inside of the first main reservoir  111  and the second main reservoir  112 , respectively. The first press  121  and the second press  122  can be joined to the upper part of the first main reservoir  111  and the second main reservoir  112 , respectively, and can be linked to the inside of the first main reservoir  111  and the second main reservoir  112 , respectively. 
     The first press  121  and the second press  122  can deliver positive pressure and negative pressure to the inside of the first main reservoir  111  and the second main reservoir  112 . The first press  121  and the second press  122  can be, for example, a pneumatic pump, which is capable of generating the positive pressure or negative pressure by rotating in either direction. 
     As shown in  FIG. 3 , when the ink is supplied to the plurality of inkjet heads  150  through the supply channel  130 , the first press  121  can give the positive pressure to the first main reservoir  111 , pushing the ink into the supply channel  130 . The second press  122  can give the negative pressure to the second main reservoir  112  and pull the ink supplied into the supply channel  130 , making it easier to supply the ink to the plurality of inkjet heads  150 . Additionally, bubbles generated insides the supply channel  130  and the plurality of inkjet heads  150  can be minimized. 
     As shown in  FIG. 4 , when the supply of ink to the plurality of inkjet heads  150  is completed, the first main reservoir  111  and the second main reservoir  112  can maintain a same ink level. In this case, the first press  121  and the second press  122  can apply negative pressure to the first main reservoir  111  and the second main reservoir  112 , respectively, thereby minimizing the lengthwise pressure difference in the supply channel  130  to a minimum. 
     The first press  121  and the second press  122  can control the pressure applied to the first main reservoir  111  and the second main reservoir  112 , respectively, such that the lengthwise pressure difference in the supply channel  130  is minimized. This can minimize the pressure difference among the plurality of inkjet heads  150  and the difference in jetting characteristics of the nozzles  145 . 
     Accordingly, even though a plurality of inkjet heads  150  are coupled to the supply channel  130 , uniform jetting characteristics among the nozzles  145  can be obtained by minimizing the pressure difference among the inkjet heads  150 , thereby improving the print quality of the inkjet printer  100 . 
     While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modification in forms and details may be made without departing from the spirit and scope of the present invention as defined by the appended claims.