Patent Publication Number: US-6334667-B1

Title: Inkjetting device for an inkjet printer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Application No. 57367/1997, filed Oct. 31, 1997, in the Korean Patent Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an inkjetting device for an inkjet printer, and more particularly, relates to an inkjetting device for continuously jetting ink drops by using a plurality of bridge and lever-type nozzle plates, which are operated by a pair of permanent magnets. 
     2. Description of the Related Art 
     Generally, the techniques applied for a conventional drop and demand-type inkjet printer head are divided into a piezo-type, a thermal-type, a continuously jetting type and so on. As shown in FIG. 1, the piezo-type has a piezoelectric element  1  to jet ink I and is used in the inkjet printer heads of the Epson company. As shown in FIGS. 2 and 3, the thermal-type has an exothermal body  2  which generates heat to jet the ink I and is used in the inkjet printer heads of the Hewlett-Packard Co., and the Canon Co., respectively. Additionally, as shown in FIG. 4, the continuously jetting type generates a magnetic force and an electrostatic force and is used in other inkjet printer heads. 
     As shown in FIG. 1, for generating a displacement, a driving signal is applied to the piezoelectric element  1  in the piezo-type inkjet printer head using the piezoelectric element  1 . The ink is jetted by transmitting the displacement to the ink I. 
     As shown in FIGS. 2 and 3, when the driving signal passes through the exothermal body  2  via an electrode (not shown), the exothermal body  2 , having a large resistance, generates heat in the thermal type inkjet printer head. The generated heat, which about boils the ink I, generates an air bubble in the ink I. Consequently, the generated air bubble jets the ink I from the inkjet printer head. 
     As shown in FIG. 4, the continuously jetting type inkjet printer head, which uses the magnetic force and the electrostatic force, has a permanent magnet  3  and a thin film coil  4  to jet the conductive ink I continuously. Accordingly, the generated magnetic force and electrostatic force by the driving signal change a moving direction of an ink drop and print the ink I onto printing paper. 
     In the piezo-type inkjetting method, a printing speed is low, the printer head cannot have a plurality of nozzles and a production yield is very low because the printer head is very expensive. Moreover, in the thermal-type inkjetting method, a life span of the printer head is short, resolution is lowered, compatibility of the ink is poor and the structure of the printer head is complex. In the continuously jetting type inkjetting method, the printer head consumes a large amount of ink and efficiency is lowered in spite of the fast printing speed. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide an inkjetting device for an inkjet printer having a simple structure. 
     It is another object of the present invention to provide an inkjetting device for an inkjet printer for reducing an amount of ink which is expended by precisely executing the inkjetting operation. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     The foregoing and other objects of the present invention are achieved by providing an inkjetting device having at least two nozzle plates arranged in a parallel line, a pair of magnets, such that a first one of the pair of magnets is formed on upper portions of the nozzle plates and a second one of the pair of magnets is formed on lower portions of the nozzle plates. Each nozzle plate includes a pair of parallel levers, which are connected to a bridge at one end portion of the nozzle plate and separated from each other at the other end portion of the nozzle plate, and a nozzle orifice formed at a front surface of the bridge, to jet ink therefrom. 
     In an embodiment of the present invention, each of the pair of magnets includes a permanent magnet and the polarity of the pair of magnets is determined by a direction of electric current selectively applied to the nozzle plates  102 ,  104 ,  106  and  108 . Preferably, the polarity of the pair of magnets and the direction of electric current applied to the lever are determined so that force can be generated to allow the parallel pair of levers which form each nozzle plate to become closer to each other. 
     Moreover, preferably, both end portions of either the upper or the lower portions of the levers of each nozzle plate are fixed to one of the pair of magnets and the remaining portion of the upper or lower of the levers is spaced apart from the one magnet by a predetermined distance. Additionally, the opposite one of the upper or lower portions of the levers is spaced apart from the other magnet of the pair of magnets. 
     The objects of the present invention will be more clearly understood through a detailed description of the preferred embodiment and the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention, and many of the attendant advantages thereof, will become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a sectional view illustrating a piezo-type inkjetting device of the Epson Co.; 
     FIGS. 2 and 3 are perspective views illustrating thermal-type inkjetting devices of the Hewlett-Packard Co., and the Canon Co., respectively; 
     FIG. 4 is a perspective view illustrating a conventional continuously jetting type inkjetting device using a magnetic force and an electrostatic force; 
     FIG. 5 is a perspective view illustrating an inkjetting device according to an embodiment of the present invention; 
     FIG. 6 is a perspective view illustrating a nozzle plate according to the embodiment of the present invention and shown in FIG. 5; 
     FIG. 7 is rear elevation of the nozzle plate shown in FIG. 6; 
     FIG. 8 is a sectional view illustrating a condition before the inkjetting device jets ink according to the embodiment of the present invention; and 
     FIG. 9 is a sectional view illustrating a condition of the inkjetting device while jetting the ink, according to the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now made in detail to the present preferred embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. 
     The objects, characteristics and advantages of the present invention will be more clearly understood through the preferred embodiment of the present invention by referring to the attached drawings. 
     In the following description, when the detailed description related to the disclosed function and structure is unnecessarily obvious in explaining the embodiment of the present invention, the detailed description will be omitted. 
     In the embodiment of the present invention, as shown in FIGS. 5 and 6, a plurality of nozzle plates  102 ,  104 ,  106  and  108  are arranged in a parallel line. Magnets, for example, permanent magnets  12  and  13 , are respectively installed on the upper and lower portions of the nozzle plates  102 ,  104 ,  106  and  108 . 
     In more detail, the nozzle plates  102 ,  104 ,  106  and  108  have a pair of parallel levers  102   a  and  102   b,    104   a  and  104   b,    106   a  and  106   b  and  108   a  and  108   b,  respectively. One end portion of each one of a pair of levers  102   a  and  102   b  is connected by a bridge  102   d  (the end portions of the pairs of levers  104   a  and  104   b,    106 a and  106   b,  and  108   a  and  108   b  are connected by respective bridges as well). The other end portion of each one of the pair of levers  102   a  and  102   b  is separated from the other end portion of the other lever of the same pair of levers  102   a  and  102   b  and forms an ink chamber  14  therebetween for receiving ink I (the other end portions of each one of the pairs of levers  104   a  and  104   b,    106   a  and  106   b,  and  108   a  and  108   b  are separated from the other portions of the other lever of the same pairs of levers, similar to that shown in FIG. 6, to form ink chambers  14 ). 
     Of course, the ink I is not only received in the ink chamber  14  as the spaces between each of the pairs of levers and the ink chambers  14  are respectively connected. But, as subsequently explained, the jetting of the ink by the operation of the levers is restricted to the ink I received in the ink chamber  14 , and accordingly, the jetted ink is considered to be separately stored in the area called the ink chamber  14 . 
     The opposite side surface to the permanent magnet  13  of each lever is spaced apart from the permanent magnet  13  by a predetermined distance. Both end portions of the nozzle plates  102 ,  104 ,  106  and  108  have lower portions which are fixed to the permanent magnet  13  and spaced apart from the permanent magnet  12  by a predetermined distance. The nozzle orifices  102   c,    104   c,    106   c  and  108   c  are respectively formed on the front surfaces of the nozzle plates  102 ,  104 ,  106  and  108 . 
     The operation of the above-mentioned inkjetting device according to the embodiment of the present invention will be described hereinafter. 
     A magnetic field of magnetic flux density B, from the permanent magnet  12  to the permanent magnet  13 , is formed by respectively installing the N-poled permanent magnet  12  and the S-poled permanent magnet  13  on the upper and lower portions of the nozzle plates  102 ,  104 ,  106  and  108 . 
     Conventionally, a Lorentz force F affects an electric charge, moving in the magnetic field. As shown in FIG. 7, the Lorentz force F is provided in a right direction with respect to the levers  102   a,    104   a,    106   a  and  108   a  when electric current i flows in the direction outwardly from the Earth&#39;s surface. Moreover, in the same manner, the Lorentz force F is produced in a left direction with respect to the levers  102   b,    104   b,    106   b  and  108   b  when the electric current i flows in the direction inwardly to the Earth&#39;s surface. 
     Accordingly, as shown in FIGS. 8 and 9, the levers  102   a  ,  104   a,    106   a  and  108   a  and the respectively corresponding levers  102   b,    104   b,    106   b  and  108   b  are affected and bent to be respectively closer to each other. Consequently, the volume in the corresponding ink chamber  14  is decreased and the ink I is jetted through the nozzle orifices  102   c,    104   c,    106   c  and  108   c.    
     That is, by selectively applying the electric current to the nozzle plates  102 ,  104 ,  106  and  108 , which are arranged between the permanent magnets  12  and  13 , in a predetermined direction, the force affects both the right and left levers of the nozzle plates  102 ,  104 ,  106  and  108  to be respectively closer to each other. Accordingly, the ink I is jetted, and printing on printing paper is executed. 
     As mentioned above, the inkjetting device according to the embodiment of the present invention jets ink by applying electric current to a nozzle plate have rectangular bridge-shaped levers. Accordingly, the inkjetting device has a simpler structure than that of the prior art and can reduce the amount of consumption of the ink I by exactly and smoothly executing the inkjetting operation. 
     As the terms mentioned in the specification are determined based upon the function of the present invention, and they can be changed according to an artisan&#39;s intention or usual practice, the terms should be determined considering the overall contents of the specification of the present invention. 
     While there have been illustrated and described what is considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. In addition, many modifications may be made to adapt a particular situation to the teaching of the present invention without departing from the central scope thereof. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims.