Abstract:
In a printer in which an inkjet head is mounted in a carriage, which is movable in a direction intersecting with a conveyance direction of a recording medium, and ink is ejected from the inkjet head to record an image onto the recording medium, there has been a problem in that the recording medium is charged due to friction and separation at the time of conveyance of the recording medium, and ink mist is attracted to a portion charged to have an unexpected pattern to be recorded. In view of this problem, static electricity generated on the recording medium is removed by providing the carriage with an ionizer for generating a positive ion and an ionizer for generating a negative ion and generating the ions at the time of scanning of the carriage. The static electricity can be removed efficiently by arranging on the carriage the ionizers for generating the ions of both polarities, namely, the positive ions and the negative ions.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an inkjet printer. 
       BACKGROUND ART 
       [0002]    There is known an inkjet printer for recording an image or the like by ejecting ink onto a recording medium, such as recording paper and a resin film. In the inkjet printer, an inkjet recording head is used in which a large number of nozzles are arranged on a nozzle surface, and ink is ejected from the nozzles to the recording medium, to thereby record a desired image. 
         [0003]    A platen is arranged at a position opposed to the recording head. The recording medium is held on the platen in a planar manner, and the ink is ejected to the held recording medium. The recording medium is conveyed while being nipped by a conveyance roller and a pinch roller, which are arranged on an upstream side of the platen. In some cases, the recording medium is charged due to, for example, static electricity generated when the recording medium is separated from the rollers or static electricity generated by friction on the platen or another conveyance path. 
         [0004]    Further, ink droplets ejected from the recording head may include not only ink droplets that account for the most part of the ejected ink, but also extremely small particles of scattered ink. Those extremely small particles of scattered ink may float as mist. When the recording medium is charged, this mist may be adhered in a concentrated manner to a portion charged, and the adhered mist may be recorded onto the recording medium to have an unexpected pattern. This pattern is a cause of deterioration of image quality. 
         [0005]    For example, in JP 06-246910 A, there is disclosed a printer for printing an object to be printed while moving a printing head relative to the object to be printed, in which static electricity removing means is arranged on an upstream side of the direction in which the printing head and the object to be printed are configured to move relative to each other so as to remove electricity on the object to be printed. 
       CITATION LIST 
     Patent Literature 
       [0006]    [PTL 1] JP 06-246910 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    In the related-art printer, as the static electricity removing means, there is used an ion generator for generating an ion for electrically neutralizing the electricity charged on the object to be printed. The ion generator is arranged on the upstream side of the direction in which the printing head and the object to be printed are configured to move relative to each other, and after the electricity is neutralized on the upstream side, the printing is performed with the use of the printing head. Further, an AC corona discharge ionizer is used as the ion generator, and the generated positive and negative ions are blown out to the object to be printed together with air. 
         [0008]    However, because the ion generator is the AC ionizer, a high AC voltage needs to be applied to a discharge needle, which necessitates a circuit for generating a high AC voltage. Moreover, when ON/OFF control is desired to be performed in order to adjust an amount of ions, a circuit scale is further increased, which necessitates a complicated circuit. This leads to a problem in that the size of a carriage is increased, and that the size of the apparatus is also increased. 
         [0009]    Further, because the positive ion and the negative ion are generated by one electrode, the ions are more frequently recombined to each other, and the ions disappear more frequently before reaching the recording medium. The related-art printer is therefore low in efficiency of removing the static electricity. 
         [0010]    In the related art, because there is also assumed a line printer having the printing head being fixed for use, a device for blowing out the air is also needed. When the device is mounted to the printing head, the printing head becomes heavier, resulting in an increase in size of the apparatus. 
         [0011]    The related art has the above-mentioned problems. 
       Solution to Problem 
       [0012]    According to one embodiment of the present invention, there is provided an inkjet printer for conveying a recording medium intermittently, ejecting ink from a recording head, and recording an image onto the recording medium, the inkjet printer including: the recording head for ejecting the ink to the recording medium from a plurality of nozzles; conveyance means for conveying the recording medium; a carriage having the recording head mounted therein, the carriage being reciprocable in a direction intersecting with a conveyance direction of the recording medium; a platen arranged so as to be opposed to a surface of the recording head on which the plurality of nozzles are arranged, for holding the recording medium being conveyed by the conveyance means; a housing having at least the platen and the carriage accommodated therein; a first ionizer for generating a positive ion; a second ionizer for generating a negative ion; a first drive circuit for driving the first ionizer; a second drive circuit for driving the second ionizer; and control means for controlling the first drive circuit and the second drive circuit, in which the first drive circuit and the second drive circuit are controlled by the control means independently of each other. 
       Advantageous Effects of Invention 
       [0013]    According the one embodiment of the present invention, it is possible to reduce the sizes and weights of the ionizers and drive circuits mounted to the recording head, and hence it is possible to remove the static electricity of the recording medium efficiently. It is thus possible to record a high-quality image by recording the image onto the recording medium from which the static electricity is removed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a cross-sectional view of an inkjet printer. 
           [0015]      FIG. 2  is an explanatory view of arrangement of suction means and exhaust means in the inkjet printer. 
           [0016]      FIG. 3  is an external view of the inkjet printer. 
           [0017]      FIG. 4  is a block diagram of the inkjet printer. 
           [0018]      FIG. 5  is a graph for showing deterioration of an ionizer. 
           [0019]      FIG. 6  is a table for showing an irradiation rate corresponding to each type of recording medium. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    An embodiment of the present invention is described with reference to the drawings. 
         [0021]      FIG. 1  is a cross-sectional view of an inkjet printer. In an inkjet printer  1 , a carriage  2  having an inkjet-type recording head mounted therein reciprocates in a depth direction of the drawing sheet. The carriage  2  is movable along a rail  8 . A platen  3  is arranged at a position opposed to a nozzle surface of the recording head. The platen  3  is formed of a flat plate, and a large number of through holes are formed in the platen  3 . A sealed space is formed below the platen  3 , and air is discharged from the sealed space by a suction fan  14 . When the air is discharged, air pressure of the sealed space is decreased. The through holes are formed in the platen  3 , and hence a recording medium arranged on the platen  3  is attracted thereonto. A large number of nozzles are formed in the nozzle surface of the recording head, and ink is ejected through the nozzles. The ink is ejected depending on a position of the carriage  2 , thereby recording a desired image on the recording medium. When the ink is ejected, in addition to ejected droplets that account for the most part of the ejected ink, a slight amount of extremely small particles of ink is scattered. Those extremely small particles of ink float as mist in the air. 
         [0022]    A front paper guide  5  is provided on a downstream side of the platen  3  along a conveyance direction of the recording medium, and a rear paper guide  4  is provided on an upstream side thereof. Conveyance rollers  6  are arranged in a portion between the rear paper guide  4  and the platen  3 . The recording medium is heated in the rear paper guide  4 , and conveyed while being nipped by the conveyance rollers  6  and pinch rollers paired with the conveyance rollers  6 . Then, the recording medium is sent to the platen  3 , and further delivered along the front paper guide  5 . A heater is also provided in each of the platen  3  and the front paper guide  5  so as to heat the recording medium. In this manner, drying of ink adhered to the recording medium is promoted. 
         [0023]    An upper portion of the rear paper guide  4  is opposed to a bending portion  21  corresponding to a portion at which an end portion of a housing  12  is bent. The bending portion  21  is bent toward an inward direction of the housing  12 , and is closer to the rear paper guide  4  as approaching a distal end thereof. Further, the distal end portion of the bending portion  21  is arranged so as to be lower than a flat portion on a surface of the platen  3  in a vertical direction. With this, a gas sucked by housing-suction fans  13  arranged on a rear surface of the housing  12  easily flows, even in a small amount, toward the downstream side in the conveyance direction of the recording medium, that is, toward the carriage  2  or a cover  7 . In other words, the sucked air is difficult to flow out through a portion between the bending portion  21  and the rear paper guide  4 . 
         [0024]    The front paper guide  5  is opposed to a distal end of the cover  7  provided above the front paper guide  5 . Further, the cover  7  is closer to the front paper guide  5  as approaching a distal end thereof. The front paper guide  5  is curved downward as approaching the downstream side in the conveyance direction of the recording medium. With the cover  7  and the front paper guide  5  configured as described above, the gas inside the housing  12  easily flows along a surface of the front paper guide  5 . The heater is arranged in a portion inside the front paper guide  5  on a rear surface side thereof, and the recording medium is heated by the heater, to thereby promote the drying of the ink adhered to the recording medium. In this case, when a solvent that evaporates in the vicinity of a surface of the recording medium stagnates, the drying of the ink is inhibited. Therefore, the stagnation of the solvent is prevented by sending air. The cover  7  is arranged closer to the front paper guide  5  so as to form an air-flow along the front paper guide  5  in a direction indicated by the arrow  15 , and is arranged so as to be oriented downward. 
         [0025]    A duct  9  is arranged above the carriage  2  so as to extend toward a rear surface of the housing  12 . A carriage-suction fan  11  is arranged at an end portion of the duct  9  on a rear surface side of the housing  12 . The housing-suction fans  13  and the carriage-suction fan  11  are arranged so as to be opposed to each other. 
         [0026]    The duct  9  is arranged at each end in a moving direction of the carriage  2 . The carriage-suction fan  11 , which serves as carriage-suction means for sucking the gas into the carriage  2 , is arranged at a distal end of each duct  9 . The gas is sucked by the carriage-suction fan  11 , and passes through the duct  9  and an inside of the carriage  2 . Then, the gas is discharged to an outside through an exhaust port  10  formed in a lower portion of the carriage  2  on the downstream side of the conveyance direction of the recording medium, that is, discharged into the housing  12 . The exhaust port  10  is directed to the cover  7 , and the discharged gas flows toward the cover  7 . The inside of the carriage  2  and a recording head  2  are cooled by the gas flowing inside the carriage  2 . The exhaust port  10  is formed into an elongated hole along the moving direction of the carriage  2 , that is, along a widthwise direction thereof. It is preferred to form an elongated hole having a width corresponding to arrangement of the recording head of the carriage  2 . With this, the gas less easily stagnates in the carriage  2  to facilitate the discharge of the gas. 
         [0027]    In a portion above the duct  9 , a flat cable  18  and an ink tube  19  are arranged so as to be routed around this portion. The flat cable  18  and the ink tube  19  are respectively connected to an electric circuit and an ink tank, which are provided outside the carriage  2 . 
         [0028]    Each housing-suction fan  13  has a height larger than a height of the carriage-suction fan  11 , which is twice as large as the height of the carriage-suction fan  11 . In other words, as the housing-suction fan  13 , a large-sized fan is used so as to suck a large amount of the outside air. The gas sucked into the housing  12  includes a gas that is sucked into the carriage  2  by the carriage-suction fan  11  and a gas that passes through the outside of the carriage  2 . The sucked air is directed toward the cover  14  arranged on a front surface of the housing  12 . The housing-suction fan  13  is prevented from being blocked by the carriage-suction fan  11 , thereby being capable of reducing a sharp change in direction of the air-flow. An upper end of the cover  7  is connected to the housing  12  in a pivotable manner. 
         [0029]    Further, the gas discharged from the exhaust port  10  is directed to the cover  7 . The cover  7  is inclined, and hence the gas blown onto the cover  7  forms an air-flow along the cover  7  in a downward direction, and further flows along the front paper guide  5 . The gas exhausted from the exhaust port  10  is discharged to the outside while being mixed with a gas flowing through the outside of the carriage  2 . The gas sucked by the carriage-suction fans  11  flows faster than the gas flowing through the outside of the carriage  2  when discharged from the discharge port  10 . Along with the air-flow from the discharge port  10 , a gas surrounding the air-flow also flows faster, and hence the gas can be smoothly discharged from a portion between the front paper guide  5  and the cover  7  to the outside. It is possible to promote the discharge of the solvent having evaporated into the gas from the ink stagnating in the housing  12 , and hence the ink can be dried in a shorter period of time. 
         [0030]    A first ionizer  16  for generating a positive ion and a second ionizer  17  for generating a negative ion are arranged on a side surface of the carriage  2 . The first ionizer  16  and the second ionizer  17  each have an opening in a downward direction, namely, in a direction toward the platen  3 , and the ions are discharged from those openings. The ions are discharged in an irradiation direction  20  of the ions. The ions discharged from the first ionizer  16  and the second ionizer  17  remove the static electricity of the recording medium. The first ionizer  16  and the second ionizer  17  are arranged at a little distance from each other along the conveyance method direction of the recording medium. The discharged ions are stirred by the air-flow within the housing  12 , but a part of the discharged ions reaches the recording medium to remove the electricity charged on the recording medium. 
         [0031]    At the time of recording, the recording medium is conveyed by a distance obtained by dividing a length of the recording head by an integer of two or more, and the recording is performed on the same area a plurality of times. For example, the printing is performed in divided parts about four to twelve times. In a printer using such a recording method, even without the use of an ionizer having a width that covers the entire width of the platen  3 , the electricity charged on the recording medium can be removed with the use of the ionizer for discharging the ion within a narrow range. Further, by supplying the ions from the ionizer to the same area the plurality of times, the electricity is removed more securely. 
         [0032]    Further, by generating the positive ion and the negative ion with the use of separate electrodes, the positive ion and the negative ion are recombined to each other less frequently so that the number of ions to reach the recording medium can be increased. It is preferred that a distance between the first ionizer  16  and the second ionizer  17  be about from 5 mm to 20 mm. When the first ionizer  16  and the second ionizer  17  are separated from each other too much, namely, separated from each other by an amount corresponding to a single conveyance of the recording medium, both of the positive ion and the negative ion cannot be supplied to the same area by a single scanning of the carriage  2 , and only one of the positive ion and the negative ion is supplied to the same area as a result. Thus, the balance between a concentration of the positive ions and a concentration of the negative ions is lost, and hence the charged electricity can no longer be removed suitably as a result. Further, by arranging the first ionizer  16  and the second ionizer  17  close to the recording medium, specifically, by setting a distance from the first ionizer  16  or the second ionizer  17  to the recording medium to from 10 mm to 30 mm, the ions are prevented from being scattered in other directions than a direction toward the recording medium.  4 Moreover, it is also possible to inhibit the recombination of the ions. When the first ionizer  16  and the second ionizer  17  are separated from the recording medium too much, the ions are diffused before reaching the recording medium, and hence the charged electricity cannot be removed. When the first ionizer  16  and the second ionizer  17  are close to the recording medium too much, both of the positive ion and the negative ion cannot be supplied to the same area, and only one of the positive ion and the negative ion is supplied to the same area as a result. Thus, the balance between a concentration of the positive ions and a concentration of the negative ions is lost, and hence the charged electricity can no longer be removed suitably as a result. 
         [0033]      FIG. 2  is an explanatory view of arrangement of suction means and exhaust means in the inkjet printer. A flow of the air in the housing  12  is described with reference to  FIG. 2 . The gas sucked into the housing  12  is discharged from a housing side surface-exhaust fan  23 , a housing rear surface-exhaust fan  22 , a portion between the rear paper guide  4  and the bending portion  21 , or a portion between the front paper guide  5  and the cover  7 , or through the suction by the platen  3 . A large number of the housing-suction fans  13  serving as housing-suction means for sucking the gas are arranged on the rear surface of the housing  12  of the inkjet printer  1 . The housing-suction fans  13  are arranged along a longitudinal direction of the housing  12 . The housing-suction fans  13  are arranged so as to be opposed to the carriage-suction fan  11 . This configuration is made to enable sucking a large amount of the air present outside the housing  12  into the carriage  2 . 
         [0034]    The rail  8  and the platen  3  are also arranged along the longitudinal direction of the housing. The platen  3  is a flat platen, and the large number of through holes are formed in the platen  3 . Below the platen  3 , there is secured a space partitioned by the platen  3 , erecting plates  20  provided below both ends of the platen  3 , and the like. A gas in the space is discharged to the outside through the suction fans  14  so as to generate negative pressure, and the recording medium conveyed on the platen  3  is sucked so as to be supported. 
         [0035]    The air flows in the following route. Specifically, the air flows from the housing-suction fans  13  toward the cover  7 , and flows downward along the cover  7  to be discharged to the outside through the gap between the front paper guide  5  and the cover  7 . 
         [0036]    A large number of the conveyance rollers  6  for conveying the recording medium are provided on the upstream side of the platen  3  along the conveyance direction of the recording medium. The conveyance rollers  6  are arranged along a longitudinal direction of the platen  3  at equal intervals. A maintenance unit  24  for the recording heads is provided on one end of the housing  12 . The maintenance unit  24  includes a wiper for wiping the nozzle surface of the recording head, and a cap for sucking ink while being held in close contact with the nozzle surface. The housing side surface-exhaust fan  23  is provided on a side surface of the housing  12  on the maintenance unit  24  side so as to exhaust the gas inside the housing  12  to the outside. Further, a space for turning when the carriage  2  reciprocates is secured on a side of the housing  12 , which is opposite to the housing side surface-exhaust fan  23  across the platen  3 . The housing rear surface-exhaust fan  22  is provided on the rear of the space, that is, the rear surface of the housing  12  so as to exhaust the gas inside the housing  12  to the outside. In this manner, the air is exhausted by the fans, thereby being capable of reducing an amount of the air discharged through the portion between the cover  7  and the front paper guide  5 . As a result, cooling of the recording medium can be suppressed in some degree. Further, the air-flow within the housing  12  also stirs the ions generated by the first ionizer  16  and the second ionizer  17  so that the ions impinge on the recording medium. 
         [0037]      FIG. 3  is an external view of the inkjet printer. In the inkjet printer  1 , the housing  12  is supported by legs  25 . The legs  25  are fixed to ends of a lower surface of the housing  12 . 
         [0038]      FIG. 4  is a block diagram of the inkjet printer. Control means  30  performs overall control in accordance with a program stored in a ROM  34 . The ROM  34  is a non-volatile memory for storing the program, an initial setting value, and the like. A RAM  33  is a RAM to function as a work area of the control means  30  and temporally store information, for example. 
         [0039]    A positive ion generator drive circuit  31  drives a positive ion generator, namely, the first ionizer  16  based on the control of the control means  30 . A negative ion generator drive circuit  32  drives a negative ion generator, namely, the second ionizer  17  based on the control of the control means  30 . A carriage motor drive circuit  27  is a motor drive circuit for moving the carriage  2 , and operates based on the control of the control means  30 . A DC ionizer and a DC drive circuit, which are easy to be controlled, are particularly preferred. 
         [0040]    Recording medium conveyance means  26  is driven based on the control of the control means  30 . The recording medium conveyance means  26  is means including the conveyance roller  6  and a motor for driving the conveyance roller  6 , for conveying the recording medium. The amount of a single conveyance of the recording medium is determined based on the number of passes at the time of recording, which is stored in image parameter storage means  29 . 
         [0041]    The image parameter storage means  29  stores, for each recording mode, data necessary at the time of image recording, such as the number of recording passes, a setting value as to whether or not to turn the first ionizer  16  and the second ionizer  17  on or off, and the control means  30  operates based on the data and program. 
         [0042]    Image recording means  28  includes an inkjet recording head and a drive circuit therefor, and operates based on the control of the control means  30 . 
         [0043]    The first ionizer  16  and the second ionizer  17  operate under the control of the control means  30 , and are controlled independently of each other. Further, the first ionizer  16  and the second ionizer  17  are controlled in a manner that corresponds to the operation of the recording medium conveyance means  26 . The first ionizer  16  and the second ionizer  17  are controlled so that the positive ion and the negative ion can be supplied to the recording medium as evenly as possible. The first ionizer  16  and the second ionizer  17  may be controlled so that one of the ionizers is turned on while the other is turned off, and the amount of ions to be discharged from each of the ionizers can be easily controlled as necessary. 
         [0044]      FIG. 5  is a graph for showing deterioration of the ionizer.  FIG. 5  is a graph in which an X-axis represents a usage time  40  of one of the first ionizer  16  and the second ionizer  17  and a Y-axis represents an amount of ions  41  generated from the ionizer. As indicated by a line  42 , the first ionizer  16  and the second ionizer  17  each have such a characteristic that as the usage time of the ionizer becomes longer, the amount of ions generated from the ionizer decreases. A usage time that has elapsed since the start of use until T 1  is defined as a first period  43 , a period from T 1  to T 2  is defined as a second period  44 , a period from T 2  to T 3  is defined as a third period  45 , and a period after T 3  is defined as a fourth period  46 . Each of the first ionizer  16  and the second ionizer  17  is set so as to reach its usage limit at around T 3 . For example, when T 3  is to be determined, time when the ionizer has deteriorated by a predetermined degree of deterioration, such as 50%, may be set as the usage limit. Further, the usage limit maybe determined depending on the recording medium to be used. When the usage time passes T 3 , the ionizer generates a smaller number of ions and the efficient deteriorates, and hence it is preferred not to use the ionizer any longer. Further, in the fourth period, the ionizer may be used continuously without an end of its operation being determined. However, in that case, the ionizer is used with recognition of a possibility that because the amount of generated ions is small, the ion can no longer be applied as intended and thus intended performance cannot be exerted. When the ionizer is used in such a manner, it is preferred that a notification function such as displaying an alert on a display be provided. 
         [0045]    Further, the ionizer for generating the positive ion and the ionizer for generating the negative ion may not have the same relationship between the usage time and the amount of generated ions, and hence it is preferred that in consideration of the characteristic of each of the ionizers, each of the ionizers be controlled with a period corresponding to the degree of deterioration being determined. Further, in the above-mentioned example, the ionizers are controlled with the periods being determined, but a function of the usage time and the degree of deterioration may be acquired in advance so that an irradiation rate is controlled based on the degree of deterioration, which is determined based on an actually measured usage time and the function. In this manner, it is possible to apply the ions more accurately. 
         [0046]      FIG. 6  is a table for showing the irradiation rate corresponding to each type of recording medium. When the ion is applied to the recording medium, an optimum irradiation amount varies depending on the type of recording medium to be used. In order to maintain this optimum irradiation amount, it is necessary to take into consideration the amount of ions generated from each of the first ionizer  16  and the second ionizer  17 , which decreases as the usage time of the ionizer passes. For example, a relationship between the type of recording medium and the irradiation rate of ions that is determined depending on the usage time is stored in the ROM  34  as a table, and such control is performed that when the type of recording medium is input, the corresponding irradiation rate can be calculated. This control can be realized by the control means  30  counting the usage time of each of the first ionizer  16  and the second ionizer  17 . 
         [0047]    In the table shown in  FIG. 6 , a medium A has irradiation rates of 0.7, 0.8, 0.9, and 1.0 in the first period  43 , the second period  44 , the third period  45 , and the fourth period  46 , respectively. This value is a value proportional to an irradiation amount. For example, when the value of the irradiation rate is 0.7, this value indicates an irradiation amount of 70%, and when the value of the irradiation rate is 0.8, this value indicates an irradiation amount of 80%. When the value of the irradiation rate is 1.0, this value indicates an irradiation amount of 100%. This irradiation amount may be controlled depending on the length of time of irradiation. A medium B has irradiation rates of 0.4, 0.6, 0.8, and 1.0 in the first period  43 , the second period  44 , the third period  45 , and the fourth period  46 , respectively. A medium C has irradiation rates of 0.6, 0.75, 0.9, and 1.0 in the first period  43 , the second period  44 , the third period  45 , and the fourth period  46 , respectively. 
         [0048]    The control means  30  includes input means and time measurement means, to thereby individually measure the usage time of each of the first ionizer  16  and the second ionizer  17 . Moreover, the control means  30  stores in advance the table associating the usage time with the irradiation rate for each recording medium. Through the use of the type of recording medium input from the input means and the usage time of the ionizer and based on the table, the control means  30  calculates the irradiation rate corresponding to the input recording medium. Then, the control means  30  controls the ion irradiation based on the thus calculated irradiation rate. 
         [0049]    The table is determined in advance so that the irradiation rate is optimum for each combination of the type of recording medium and the usage time. It is possible to facilitate control such as calculation processing by storing the table and calculating the irradiation rate based on the stored table. Further, instead of using the table, the control means  30  may store a function so as to alternatively perform processing of calculating the degree of deterioration and the irradiation rate based on the usage time. More accurate control is performed with this configuration, but a calculation amount may increase. 
         [0050]    Further, it is preferred that when the usage time reaches the fourth period  46 , namely, the usage time exceeds T 3 , an alert for prompting replacement of the first ionizer  16  and the second ionizer  17  be issued. This is because although the ionizer at least operates even when applying the ions continuously at the irradiation rate of 100%, the effect of irradiation may be insufficient because the amount of generated ions is small. 
       INDUSTRIAL APPLICABILITY 
       [0051]    The present invention is applicable to an inkjet printer. 
       REFERENCE SIGNS LIST 
       [0052]      1  inkjet printer 
         [0053]      2  carriage 
         [0054]      3  platen 
         [0055]      4  rear paper guide 
         [0056]      5  front paper guide 
         [0057]      6  conveyance roller 
         [0058]      7  cover 
         [0059]      8  rail 
         [0060]      9  duct 
         [0061]      10  exhaust port 
         [0062]      11  carriage-suction fan 
         [0063]      12  housing 
         [0064]      13  housing-suction fan  13   
         [0065]      14  suction fan 
         [0066]      16  first ionizer 
         [0067]      17  second ionizer 
         [0068]      22  housing rear surface-exhaust fan 
         [0069]      23  housing side surface-exhaust fan 
         [0070]      24  maintenance unit