Abstract:
In an inkjet recording apparatus including an ink and solvent containers, they are coupled with each other through a first exhaust channel, an exhaust gas and ink mist within the ink container are supplied to the solvent container through the first exhaust channel, and the solvent container has an ink mist removal unit removing the ink mist supplied from the first exhaust channel.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an inkjet recording apparatus that conducts printing by ejecting ink from a nozzle. 
         [0002]    In an inkjet recoding apparatus of a so-called continuous system, ink is ejected from a nozzle, only ink particles for use in printing are charged by a charging electrode, a flying direction of the charged ink particles is deflected by a deflection electrode to conduct printing. Ink particles not used for printing are sucked and recovered into a gutter, and again used for printing. In the gutter, circumambient air is also sucked while the ink particles are sucked and recovered. The sucked air is discharged from an interior of an ink container toward an exterior thereof because the air is continuously fed into the ink container (for example, refer to Japanese Unexamined Patent Application Publication No. 2009-172932). 
       SUMMARY 
       [0003]    In Japanese Unexamined Patent Application Publication No. 2009-172932, within a recovery route for sucking the ink and the air from the gutter to recover the ink and the air within the ink container, ink mist occurs, and the ink mist drifts from the recovery route into the air within the ink container. The air within the ink container is discharged from an outlet provided in an inkjet recording apparatus main body toward an exterior of the inkjet recording apparatus main body. The ink mist within the ink container is collected into an ink liquid within a route through which the ink mist is discharged to the exterior of the inkjet recording apparatus, and the ink is spilled out of the outlet, resulting in a possibility that the circumference is contaminated with the ink. 
         [0004]    Also, in the gutter, the ink as well as the ink is sucked and pumped into the ink container with the use of a pump located in the recovery route. Thereafter, the ink is accumulated in a lower portion of the ink container, and the air drifts in an upper portion of the ink container. However, the air within the upper portion of the ink container passes through an exhaust route located in the ink container, and is exhausted toward the exterior of the ink container because a fresh air continues to be fed into the ink container from the gutter without interruption. 
         [0005]    In this case, a required flow rate of the air is about 80 to 200 [ml/min]. When the flow rate of the air to be sucked from the gutter becomes lower, an ink flow within the gutter becomes slow, and the ink may be spilled from a leading end of the gutter. (Conversely, when the flow rate of the air to be sucked from the gutter becomes higher, a larger amount of solvent component in the ink is volatilized within the recovery route, and the running costs are increased in order to exhaust the volatilized solvent.) 
         [0006]    That is, in Japanese Unexamined Patent Application Publication No. 2009-172932, the ink mist is collected into the ink and deposited in the exhaust route to narrow the exhaust route, to thereby decrease the flow rate of the air that can be discharged from the exhaust route. This makes it difficult to suck the fresh ink and air from the gutter (because the flow rate of the air to be sucked from the gutter is decreased). As a result, there is a risk that the ink is spilled out of the gutter, and the circumference is contaminated with the ink. 
         [0007]    An object of the present invention is to prevent discharge of the ink mist generated within the recovery route toward the exterior of the device, and the deposition of the ink within the route. 
         [0008]    In order to solve the above problem, for example, there is provided an inkjet recording apparatus including: an ink container for storing ink which is housed in a main body; a solvent container that accommodates solvent for supplying the solvent to the ink container in order to adjust a concentration of the ink within the ink container; a nozzle that ejects the ink supplied from the ink container through an ink supply channel as ink particles to conduct printing on an object to be printed; a gutter for recovering the ink particles not used for printing among the ink particles ejected by the nozzle; an ink recovery channel for recovering the ink particles recovered by the gutter into the ink container; and a second exhaust channel that discharges a gas recovered together with the ink particles through the ink recover channel from the solvent container to an exterior of the main body, in which the ink container and the solvent container are coupled with each other through a first exhaust channel, an exhaust gas and ink mist within the ink container are supplied to the solvent container through the first exhaust channel, and the solvent container is equipped with an ink mist removal unit that removes the ink mist supplied from the first exhaust channel. 
         [0009]    According to the aspect of the present invention, the deposition of the ink mist that flows in the exhaust channels together with the gas within the exhaust routes can be reduced. 
         [0010]    Also, according to the aspect of the present invention, ink contamination of the circumference of the inkjet recording apparatus caused by allowing the ink mist to be discharged to the exterior can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a main body and a print head in an inkjet recording apparatus; 
           [0012]      FIG. 2  is a perspective view illustrating a basic operation of the inkjet recording apparatus; 
           [0013]      FIG. 3  is a perspective view illustrating a use state of the inkjet recording apparatus; 
           [0014]      FIG. 4  is a configuration diagram illustrating a route of an inkjet recording apparatus according to a first embodiment of the present invention; 
           [0015]      FIG. 5  is an enlarged view of an ink recovery route; 
           [0016]      FIG. 6  is an enlarged view of an exhaust route (before mist removal); 
           [0017]      FIG. 7  is an enlarged view of the exhaust route (after mist removal); 
           [0018]      FIG. 8  is a vertically cross-sectional view illustrating a solvent container having a mist removal function according to an embodiment of the present invention; 
           [0019]      FIG. 9  is a horizontally cross-sectional view illustrating the solvent container having the mist removal function according to the embodiment of the present invention; 
           [0020]      FIG. 10  is a vertically cross-sectional view illustrating a state in which a fluid level in the solvent container having the mist removal function is low according to an embodiment of the present invention; 
           [0021]      FIG. 11  is a cross-sectional view illustrating an exhaust gas discharge opening within the solvent container in the inkjet recording apparatus according to the embodiment of the present invention; and 
           [0022]      FIG. 12  is a diagram illustrating the amount of solvent within the solvent container and a change in ink concentration according to the embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiment. 
       Embodiment 
     (Configuration of Apparatus Exterior) 
       [0024]      FIG. 1  is a perspective view illustrating an inkjet recording apparatus  100 . The inkjet recording apparatus  100  includes a main body  1  externally equipped with an operation display unit  3 , and a print head  2 . The main body  1  and the print head  2  are connected to each other by a conducting pipe. 
       (Operation Principle of Apparatus) 
       [0025]    Now, an operation principle of the inkjet recording apparatus  100  will be described. As illustrated in  FIG. 2 , an ink  7 A within an ink container  18  is sucked and pressurized into an ink column  7 B by a pump  25 , and then ejected from a nozzle  8 . The nozzle  8  is equipped with an electrostrictive element  9 , which subjects the ink to vibration at a given frequency so as to particulate the ink column  7 B to be ejected from the nozzle  8 . The number of ink particles  7 C thus generated is determined according to a frequency of an excitation voltage to be applied to the electrostrictive element  9 , and have the same number as the frequency. The ink particles  7 C are given electric charge by applying a voltage having a magnitude corresponding to print information by charging electrodes  11 . The ink particles  7 C charged with the charging electrodes  11  are subject to a force proportional to the amount of electric charge and deflected while flying in an electric field between deflection electrodes  12 . Then, the ink particles  7 C fly toward an object to be printed  13 , and lands thereon. In this situation, a landing position of the ink particles  7 C in the deflection direction is changed according to the amount of electric charge, and a production line moves the object to be printed  13  in a direction orthogonal to the deflection direction with the result that the particles can be landed even in the direction orthogonal to the deflection direction, and a character is configured by a plurality of landing particles to conduct printing. 
         [0026]    The ink particles  7 C that have not been used for printing fly linearly between the deflection electrodes  12 , pass through the route after having been trapped by a gutter  14 , and are recovered into the main ink container  18 . 
       (Use Form of Apparatus) 
       [0027]    An example of actual use forms of the inkjet recording apparatus  100  is illustrated in  FIG. 3 . The inkjet recording apparatus  100  is installed in the production line within a factory where, for example, foods or beverages are produced. The main body  1  is located at a position where a user can operate the main body  1 , and the print head  2  is located at a position where the print head  2  can come close to the object to be printed  13  which is fed on the production line such as a belt conveyer  15 . 
         [0028]    In order to print with the same width regardless of a feed speed, on the production line such as the belt conveyer  15  are located an encoder  16  that outputs a signal responsive to the feed speed to the inkjet recording apparatus  100 , and a print sensor  17  that detects the object to be printed  13 , and outputs a signal for ordering printing to the inkjet recording apparatus  100 . The encoder  16  and the print sensor  17  are connected to a controller not shown within the main body  1 . The controller controls the amount of electric charge and a charging timing to the ink particles  7 C ejected from the nozzle  8  according to signals from the encoder  16  and the print sensor  17 , and attaches the charged and deflected ink particles  7 C to the object to be printed  13  while the object to be printed  13  is passing through a neighborhood of the print head  2 , for conducting printing. 
       (Route Configuration of Embodiment) 
       [0029]      FIG. 4  is an illustrative view illustrating an overall route configuration of the inkjet recording apparatus  100 . The main body  1  is equipped with the main ink container  18  that retains a circulating ink therein. The main ink container  18  is equipped with a viscosity measurement unit  21  which is a falling ball viscometer for measuring a viscosity of the ink through a route  101  for circulating the ink. 
         [0030]    The viscosity measurement unit  21  is connected to an electromagnetic valve  22  that opens and closes the route through a route  102 , and the electromagnetic valve  22  is connected to the pump  25 , which contributes to the suction and pumping of the ink and the solvent, through a route  103 . The pump  25  is connected to a filter  28 , which removes foreign material mixed in the ink, through a route  104 . 
         [0031]    The filter  28  is connected to a pressure reducing valve  30 , which adjusts a pressure of the ink pumped from the pump  25  to a pressure suitable for printing, through a route  105 . The pressure reducing valve  30  is connected to a pressure sensor  31  for detecting the ink pressure through a route  106 . 
         [0032]    The pressure sensor  31  is connected to the nozzle  8  having an ejection port for ejecting the ink, which is disposed within the print head  2 , through a route  107  that passes into a conducting pipe  4 . 
         [0033]    The charging electrodes  11  that charge ink particles  10  ejected from the nozzle  8  with the amount of electric charge corresponding to character information to be printed are disposed in an ink ejection direction of the nozzle  8 . Deflection electrodes  12 , which develop an electric field for deflecting the charged ink particles  10 , are disposed in the flying direction of the ink particles  7 C charged by the charging electrodes  11 . 
         [0034]    The gutter  14 , which traps the ink particles  7 C that linearly fly without being charged and deflected because the ink particles  7 C are not used for printing, is disposed on an ink flying direction side of the deflection electrodes  12 . The gutter  14  is connected to a filter  29  for removing the foreign material mixed in the ink, which is arranged within the main body  1 , through a route  108  that passes through the conducting pipe  4 . The filter  29  is connected to a pump  26 , which sucks the ink particles  7 C trapped by the gutter  14 , through a route  109 . The pump  26  recovers the sucked ink particles  7 C into the main ink container  18  through a route  110 . 
         [0035]    Also, the main body  1  is equipped with a solvent container that accommodates a solvent  53  for eliminating the ink contamination of the nozzle  8  and adjusting the concentration of the ink. The solvent container  20  is connected to a pump  27 , which sucks and pumps the solvent, through a route  111 . Also, the pump  27  is connected to an electromagnetic valve  24 , which opens and closes the route, through a route  112 , and the electromagnetic valve  24  is connected to the main ink container  18  through a route  113 . 
         [0036]    Further, the main body  1  is equipped with an auxiliary ink container  19  that retains a replenishment ink therein, and the auxiliary ink container  19  is connected to an electromagnetic valve  23 , which opens and closes the route, through a route  120 . The electromagnetic valve  23  is connected to the route  103  through a route  121 . 
       (Exhaust Route) 
       [0037]    As illustrated in  FIG. 4 , the gutter  14  also sucks a circumambient air while the ink particles  7 C are sucked and recovered. The sucked air is discharged is fed into the main ink container  18 , and discharged from the interior of the main ink container  18  to the exterior of the main body  1  through a route  40 . 
         [0038]    The main body  1  is equipped with an outlet  32 , and the outlet  32  is connected to a gas portion  44  of the solvent container  20  through a route  45 . A volatilized solvent component in the ink is exhausted to the exterior of the main body  1  through the route  45 . A gas portion  80   c  of the main ink container  18  is connected to a gas exhaust port  60  of the solvent container  20  through a route  41 , and the gas exhaust port  60  is arranged in the solvent  53 . 
       (Description of Solvent Container According to the Invention) 
       [0039]      FIG. 8  illustrates a vertically cross-sectional view of the solvent container  20  according to an embodiment of the present invention, which is a cross-sectional view ( FIG. 9 ) taken along a line A-A in  FIG. 8 . 
         [0040]    The solvent container  20  according to this embodiment includes a solution storage unit  50  that retains the solvent  53  therein, and an upper cover  51  that is disposed on an upper side of the solution storage unit  50 . In this example, the solution storage unit  50  and the upper cover  51  are fixed to each other, for example, with hot plate welding, or screws. 
         [0041]    The upper cover  51  includes a fluid level sensor  52  that detects a fact that a fluid level  53   a  of the solvent  53  falls below a given value, a pipe (for solvent supply)  111   a  that is connected to the route  111 , a pipe (for exhaust IN)  41   a  that is connected to the route  41 , and a pipe (for exhaust OUT)  45   a  that is connected to a route  46 . The pipe (for solvent supply)  111   a  is configured to have a leading end immersed in the solvent  53 . The leading end of the pipe (for exhaust OUT)  45   a  is disposed above the fluid level  53   a,  and contacts with an exhaust gas  81   c.    
         [0042]    The pipe (for exhaust IN)  41   a  has a leading end connected to the gas exhaust port  60 . The gas exhaust port  60  is arranged to be immersed in the solvent  53 , and designed to discharge an exhaust gas (air bubble)  81   d  into the solvent  53 . 
         [0043]    The solution storage unit  50  is equipped with a partition  50   a.  The provision of the partition  50   a  makes it possible to prevent the exhaust gas (air bubble)  81   d  from affecting the detection of the fluid level  53   a  by the fluid level sensor  52 . In this example, as illustrated in  FIG. 9 , a gap  50   b  is formed between the partition  50   a  and one surface of wall surfaces configuring the solution storage unit  50 , and the solvent  53  flows into the gap  50   b.    
         [0044]      FIG. 10  illustrates a state in which the fluid level  53   a  within the solvent container  20  is lowered. The fluid level sensor  52  detects a fact that the fluid level  53   a  is lowered, and issues an alarm for ordering the replenishment ink of the solvent  53 . Even in this state, the gas exhaust port  60  is lower than the fluid level  53   a,  and immersed in the solvent  53 . The upper cover  51  includes a spout  56  for replenishing the solvent  53 , a filter  55  that is arranged in the spout  56  for the purpose of preventing dust from being mixed into the solvent container  20 , and a cap  54  that can be opened and closed when replenishing the solvent  53 . 
       (Description of Gas Exhaust Port  60 ) 
       [0045]    A configuration of the gas exhaust port  60  will be described with reference to  FIG. 11 . The gas exhaust port  60  includes a body  62  that is connected to the pipe (for exhaust IN)  41   a,  a base  61  that is disposed below the body  62 , a porous component  63  that is installed on an upper portion of the body  62 , and a ring  64  and a nut  65  which are disposed to fix the porous component  63 . 
         [0046]    Arrows in  FIG. 11  represent a flow of an exhaust gas  81   a . The exhaust gas  81   a  flows together with an ink mist  82   a,  and at least a part of the ink mist  82   a  is dissolved in the solvent  53  when the exhaust gas  81   a  passes through the porous component  63 . Also, the exhaust gas  81   a  becomes the exhaust gas (air bubble)  81   d  when the exhaust gas  81   a  passes through the porous component  63 . The exhaust gas (air bubble)  81   d  goes up within the solvent  53 , and joins the exhaust gas (upper portion of solvent container)  81   c.    
       (Ink Concentration of Solvent) 
       [0047]    The solvent  53  in the solvent container  20  dissolves the ink mist  82   a  to raise the ink concentration.  FIG. 12  is a diagram illustrating the amount of solvent within the solvent container and a change in ink concentration according to the embodiment of the present invention. 
         [0048]    In the figure, symbol T 0  is 0 time of operation, T 1  to T 3  are solvent replenishment times, C 0  is ink concentration 0%, C 1  is the ink concentration of the solvent  53  immediately before replenishment, C 2  is the ink concentration of the solvent  53  immediately after replenishment, V 0  is the amount 0 ml of the solvent  53 , V 1  is the amount of the solvent  53  immediately before replenishment, and C 2  is the amount of the solvent  53  immediately after replenishment. In this example, it can be confirmed that the ink concentration of the solvent  53  is not equal to or more than a given value. For example, when it is assumed that a decrement (the amount of volatilization) of the solvent  53  is 5 ml and V 1  is 1000 ml at the time of ejecting the ink, the maximum ink concentration C 1  is about 0.01%. The ink concentration of the solvent  53  is of the level affecting the apparatus. 
       (Ink Mist in Exhaust Route, and Advantages of the Invention) 
       [0049]      FIG. 5  illustrates a cross-sectional view of the ink recovery route. In the routes  108  to  110 , an ink  7   d  and an air  80   b  flow together to generate an ink mist  82   a.    FIG. 6  illustrates a cross-sectional view of the route (for exhaust)  41 . In the route  41 , an exhaust gas  81  as well as an ink mist  82   a  flow.  FIG. 7  illustrates a cross-sectional view of the route (for exhaust)  45 . The route  45  is smaller in the amount of ink mist  81   c  than the route  41 . 
         [0050]    According to the present invention, because the discharge of the ink mist  81   c  to the exterior of the apparatus can be reduced, there can be used the inkjet recording apparatus that can keep the clean circumference of the apparatus.