Abstract:
An ink jet recording apparatus for recording onto a recording medium using an ink jet recording head which discharges ink, comprises a conveyor for conveying the recording medium, a head mount means for mounting an ink jet recording head, a fan for generating an air flow for transporting ink which is generated by ink discharged from the ink jet recording head, floating in the inside of the ink jet recording apparatus, and unused for recording, the fan being disposed in the downstream of the air flow, and an air guiding member for guiding the air flow in said ink jet recording apparatus to the fan, said air guiding member being provided with an aperture section for sucking the air flow into said air guiding member, and removably connected to the sucking the of said fan.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet recording apparatus for discharging ink onto a recording medium to record thereon. 
     2. Related Background Art 
     In recent years, an ink jet recording apparatus for discharging ink onto a recording medium for forming an image or the like has been spectacularly pervasive for office and home use. The pervasion owes not only to an improvement in the recording speed and a reduction in price, but also to higher definition of a recorded image. In order to achieve the higher definition of the recorded image, a reduced diameter and higher density of ink discharging ports of an ink jet recording head are indispensable, and as the result, the size of ink droplets discharged therefrom has also been reduced. 
     However, the reduction in size of the ink droplets has given rise to a problem that, when ink is discharged, a minute ink particles called ink mist are generated, and the ink mist disperses and stains a recording medium and the inside of the recording apparatus. Further, when the ink mist dispersed in the recording apparatus deposits on a mechanism for recording operation in the recording apparatus, means for controlling therefor, or the like, malfunction may be caused. In order to prevent the malfunction, the recording apparatus may be provided with a suction fan to employ a method of collecting the dispersed ink mist making use of the suction fan. However, when the ink jet recording apparatus is used for long time, another problem has been caused that the ink mist sucked by the fan is deposited in a sucking route to gradually reduce a sucking efficiency, and further, the ink mist is deposited too much in the sucking route to hold the ink mist therein. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is, generally, to provide an ink jet recording apparatus of excellent reliability, which prevents staining in the recording apparatus by ink mist and malfunction thereof, and ensures recording of an image in a stabilized way for an elongated time, by efficiently collecting for an elongated time ink mist generated by the discharged ink and dispersed in the inside of the recording apparatus. 
     More specifically, another object of the present invention is to provide an ink jet recording apparatus for recording onto a recording medium using an ink jet recording head, comprising conveying means for conveying the recording medium, head mounting means for mounting an ink jet recording head, a fan for generating an air flow for transporting ink which is generated by the ink discharged from the ink jet recording head, floating in the ink jet recording apparatus, and unused for recording, the fan being disposed in the downstream of the air flow, and an air guiding member for guiding the air flow in the ink jet recording apparatus to the fan, the air guiding member being provided with an aperture section for sucking the air flow into the air guiding member, and removably connected to the sucking side of the fan. 
     Still another object of the present invention is to provide an ink jet recording apparatus for recording onto a recording medium using an ink jet recording head which discharges ink, comprising conveying means for conveying a recording medium, a head mounting means for mounting an ink jet recording head, air flow generating means for generating an air flow for transporting ink which is generated by ink discharged from the ink jet recording head, floating in the inside of the ink jet recording apparatus, and unused for recording, and an ink containment member for containing the floating ink unused for recording by containing the air flow into the inside thereof, the ink containment member having a space provided inside thereof for containing the floating ink unused for recording. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic sectional view of an embodiment of the ink jet recording apparatus according to the present invention. 
     FIG. 2 is an enlarged sectional view of the surrounding of the recording section of the ink jet recording apparatus shown in FIG.  1 . 
     FIG. 3 is a horizontal sectional view of the ink jet recording apparatus shown in FIG.  1 . 
     FIG. 4 is a sectional view taken along a line  4 — 4  the ink jet recording apparatus shown in FIG.  3 . 
     FIG. 5 is a sectional view taken along a line  5 — 5  of the ink jet recording apparatus shown in FIG.  3 . 
     FIG. 6 is a diagram describing an outline of air flow route from upstream to downstream of the conveying direction of a recording paper, in the ink jet recording apparatus shown in FIG.  1  and others. 
     FIG. 7 is a diagram describing an outline of an air flow sucked from a recording region, in the ink jet recording apparatus shown in FIG.  1  and others. 
     FIG. 8 is a diagram describing an outline of an air flow sucked from the recording region, in a case where a member containing ink mist is arranged separately from paper expelling means. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, embodiments of the present invention will be described with reference to the drawings. 
     FIG. 1 is a schematic sectional view of an embodiment of the ink jet recording apparatus according to the present invention. The ink jet recording apparatus of the present embodiment is a serial type ink jet recording apparatus having a recording head  1  mounted on a carriage  2  which is reciprocally traveled in a direction different from the conveying direction of a recording medium, for example, to an orthogonal direction, for discharging ink from the recording head while the recording head  1  is traveling to record on a recording medium, while alternately repeating a reciprocal traveling of the recording head  1  following to the traveling of the carriage  2  and a feeding of the recording medium at each predetermined pitch, and FIG. 1 is a sectional view cut at the middle of the width direction (traveling direction of the recording head  1 ) of the recording medium along the conveying direction of the recording medium. 
     And FIG. 2 is an enlarged sectional view of the surrounding of the recording section of the ink jet recording apparatus shown in FIG. 1. A description will be made hereunder of a mechanism pertinent to the recording motion of the ink jet recording apparatus according to the present embodiment with reference to FIGS. 1 and 2. 
     The carriage  2  is slidably held by a carriage haft  3  and a guide rail  4  which are arranged and secured mutually in parallel on a plate-shaped chassis  20  which composes a base of the record motion mechanism of the ink jet recording apparatus. To the carriage  2 , secured is a part of a timing belt (not shown) wounded around two pulleys (not shown) rotatably provided with an interval therebetween in the shaft direction of the carriage shaft  3 , and by forward rotation and reverse rotation of a carriage driving motor (not shown), the carriage  2  is reciprocally traveled along the carriage shaft  3 . 
     The recording head  1  has a plurality of discharging ports (not shown) for discharging ink, and is removably mounted on the carriage  2  with the discharging port surface, which is the surface where these discharging ports have openings, facing downward. Methods for making ink to be discharged from the discharging ports include broadly a method to provide thermal energy to the ink by a heater to utilize the change of state of the ink (generation of air bubble and the like) due to the thermal energy, and another method to provide mechanical energy to the ink by a piezoelectric element thereby to momentarily apply discharging pressure thereto, but in the present invention, the recording head of whichever the methods is applicable. 
     The recording head  1  and the carriage  2  mutually have an electrically connected section (head contact section) which are electrically connected, by having the recording head mounted on the carriage  2 . To the recording head  1 , a recording signal is fed from a control section on the side of the ink jet recording apparatus body via the electrically connected section, and based on the recording signal, thermal energy or mechanical energy is applied to the ink. 
     Further, on the chassis  20 , a scale  32  is provided in an interval with the carriage  2  along the traveling direction of the carriage  2 , and on the part of the carriage  2  facing to the chassis, a reading sensor  31  for reading the scale  32  is provided, and the scale  32  and the reading sensor  31  compose a linear encoder for detecting the position of the carriage  2  at a width direction of the recording medium. 
     As the linear encoder, an optical type or a magnetic type may be used, and for example, in a case of the optical type, the scale  32  is provided with a multiplicity of slits arranged in the traveling direction of the carriage  2  in a predetermined pitch, and as the reading sensor  31  an optical sensor is used. The position of the carriage  2  detected by the linear encoder is utilized for feed-back control of the above-mentioned carriage driving motor and control of ink discharging timing from the recording head  1 . In other words, the linear encoder composes a means for traveling the carriage  2  together with the carriage shaft  3  holding the carriage  2 . 
     Below the carriage  2 , a carrier mechanism for conveying the recording medium is provided. In the present embodiment, the recording medium can be selectively conveyed from an auto sheet feeder  200  provided in the rear of the carriage  2 , or a cassette  300  provided below the carriage  2 . 
     The auto sheet feeder  200  holds a multiplicity of a recording paper  150  being the recording medium loaded thereon, and when a paper feeding roller  202  disposed at the down end of the recording paper  150  is rotated to touch the recording paper  150 , the recording paper  150  is separated sheet by sheet by an action with a separating claw  203  to be conveyed in a direction indicated by an arrow A shown in FIG.  1 . The separated recording paper  150  is led to a feeding path  101  by a recording paper direction regulating plate  204 , and held between a conveying roller  102  driven by a paper feeding driving motor (not shown) and a pinch roller  103  which is rotatably held by a shaft on a pinch roller holding plate  104  urged toward the conveying roller  102  by an urging spring  105 , and placed opposingly in relation to the conveying roller  102 . When the paper feeding driving motor is driven here, the recording paper  150  is conveyed to a position below the recording head  1 , namely to the position facing to the discharging port surface. 
     In the downstream of the conveying direction of the recording paper  150  by the conveying roller  102  and the pinch roller  103 , a platen  106  is arranged facing with the discharging port surface of the recording head  1 , and recording is performed on the platen  106  by discharging the ink from the recording head  1 . On the platen  106 , a paper pressing plate  107  formed by a plate member having rigidity is provided, and the recording paper  150  held between the conveying roller  102  and the pinch roller  103  is conveyed while being pressed by the platen  106  against the paper pressing plate  107 . In this way, the recording paper  150  is prevented from being touched with the discharging port surface of the recording head  1 , and an opposing distance between the recording paper  150  and the discharging port surface is kept constant to maintain at high accuracy the impinging position of the ink onto the recording paper  150 . 
     The recording paper  150  conveyed over the platen  106  is further held between a paper expelling roller  108  arranged in downstream of the conveying direction and a spur  109 , which is a rotary member for expelling paper on the other side, pressed to touch the paper expelling roller  108 , and released on the paper expelling tray  120  to be stacked thereon. Although the spur  109  will be later described in detail, the spur  109  is provided in width direction in a plural number with an interval between the respective spurs. 
     The cassette  300  also holds a multiplicity of the recording paper  150  loaded thereon, and sheet by sheet separation of the recording paper  150  loaded on the cassette  300  is, similarly with the auto sheet feeder  200 , performed by an action of the pickup roller  202  and the separation claw  203  to be conveyed to a direction indicated by an arrow B in FIG.  1 . The recording paper  150  conveyed to the direction of the arrow B is held between the feeding roller  204  which is a driving roller, and a feeding roller  205  which is a subordinate roller pressed to touch the feeding roller  204 , and led to the feeding path  101  through a cassette conveying path  206 . As the conveying path and operation hereafter is similar to the auto sheet feeder  200 , the description is omitted. 
     Besides, a chassis  20  aligns and holds the above described carriage shaft  3 , the guide rail  4 , the auto sheet feeder  200 , the carriage driving motor, the paper feeding driving motor and the like, and rotatably holds the conveying roller  102  and the paper expelling roller  108 . 
     Further, as illustrated in the horizontal sectional view in FIG. 3, within the reciprocal traveling range and at the right outside edge of the region where the recording paper  150  passes, arranged is a head recovery system unit  10  provided with a sucking mechanism for forcibly sucking ink from the discharging port separately from the recording head  1  in order to maintain or recover the discharging function of the recording head  1 , a wiping mechanism for wiping the discharging port surface in order to clean the discharging port surface of the recording head  1 , a capping mechanism for tightly sealing the discharging port surface of the recording head in order to prevent dehydration of the ink in the discharging ports of the recording head  1  at non-recording time, and the like. 
     The recording head  1  is traveled to a position facing with the head recovery system unit  10  at non-recording time and at a constant time interval, and the predetermined recovery processing at this position such as a sucking operation by the sucking mechanism, a wiping operation by the wiping mechanism, or the like maintains the discharging characteristic in good condition. Moreover, the reference position (home position) of the recording motion by the recording head  1  is set at the end of the side where the head recovery system unit  10  of the recording region (a range where the carriage  2  is reciprocally traveled at the recording operation time) is provided, and based on the reference position, traveling of the carriage  2  for recording by the recording head  1  and traveling of the carriage  2  for recovery processing of the recording head  1  are controlled. 
     Further, in the present embodiment, the discharging operation of the ink from the recording head  1  is performed only when the recording head  1  is traveling from side of the reference position to the side of the non-reference position (in FIG. 3, from the right to the left). This is because, by always keeping constant the traveling direction of the recording head  1  at the time when the ink is discharged, the impinging accuracy of the ink onto the recording paper  150  is improved and a color image of high definition and high accuracy is enabled to be recorded. 
     In order to achieve an image of higher definition in the recording by the recording head  1 , a smaller diameter and higher density of the discharging ports of the recording head  1  have been studied. As the result, the size of the discharging ink droplet is reduced, but following thereto, a multiplicity of minute ink particles (ink mist) are generated at the time of the ink discharging to disperse in the ink jet recording apparatus. 
     Thereupon, in the present embodiment, in order to efficiently control a flow of the ink mist, two fans comprising a blow fan  40  and a suction fan  48  are provided, as illustrated in FIG. 3, to form an air flow to be later described of the predetermined direction in the recording apparatus. The air flow by these blow fan  40  and suction fan  48  will be described hereunder with reference to FIG. 2 to FIG.  5 . Besides, FIG. 4 is a sectional view taken along an  4 — 4  line of the ink jet recording apparatus illustrated in FIG. 3, and FIG. 5 is a sectional view taken along an  5 — 5  line of the ink jet recording apparatus illustrated in FIG.  3 . 
     The blow fan  40  is for blowing air from the outside into the inside of the ink jet recording apparatus, and is positioned at the upstream of the carriage  2  relative to the conveying direction of the recording paper  150  and in the neighborhood of the head recovery system unit  10  in the side of the reference position relative to the traveling direction of the carriage  2 . By the blow fan  40 , within the region where the carriage  2  arranged in the inside of the ink jet recording apparatus is traveled, broadly speaking, formed is an air flow from the upstream to the downstream of the conveying direction of the recording paper  150 . Owing to the air flow, the ink mist generated by the discharging of ink from the recording head  1  flows toward the expelling direction of the recording paper  150 , and therefore, the ink mist can be efficiently controlled without being dispersed in the ink jet recording apparatus. 
     An outline of the air flow path from the upstream to the downstream of the conveying direction of the recording paper  150  will be described with reference to FIG.  6 . 
     The air flow generated by the blow fan  40  at first impinges the back of the chassis  20  and flows upward along the chassis  20  to impinge a housing cover  42  covering an upper part of the chassis  20 . A greater part of the air flow which impinges the housing cover  42  rides over the chassis  20  to flow forward, but a part of the air flow causes to generate a downward flow (the flow in a direction indicated by an arrow of a dotted line) on the back of the chassis  20  in the side of the above described non-reference position. The downward flow is blown to the paper feeding roller  202 . 
     Meanwhile, the air flow which flows toward the forward of the chassis  20  flow downward along the shape of the housing cover  42 , and passes through an interval between the carriage  2  and the chassis  20  to be blown onto the above described linear encoder, the carriage shaft  3 , and the like. Further, the air flow impinges the paper pressing plate  107  which covers the conveying roller  102  and the pinch roller  103 , where the flow direction is changed to a direction along the conveying direction of the recording paper  150 , passes through an interval between the recording head  1  and the recording paper  150 , more specifically, through a recording region, a region facing to the platen  106 , and flows toward the paper expelling side having the paper expelling roller  108  and the spurs  109 . 
     Besides, as above described, since the air flow generated by the blow fan  40  passes through the recording region, output of the blow fan  40  is made to be the output of a degree such that the air flow in the recording region is not powerful enough to affect a dispersing flight of the ink discharged from the recording head  1 . 
     The air flow by the blow fan  40  will be described hereunder more in detail. As illustrated in FIG. 4, the blow fan  40  is arranged so as to blow out an air from the below to the above thereof, and forms a flow, as illustrated by an arrow D in FIG. 4, that sends upward the air taken in from the outside via an outside air intake duct  41 . 
     As the chassis  20  exists between the blow fan  40  and the carriage  2 , as illustrated in FIG. 4, the air blown out from the blow fan  40  is suspended from directly flowing into the side of the carriage  2 , and impinges a ceiling part of an inner wall of the housing cover  42  covering the whole of the ink jet recording apparatus (chassis  20 , carriage  2 , conveying mechanism, and the like). The ceiling part forms a concave curved surface seen from the inside of the housing cover  42 , and the air which impinges the ceiling part rides over the chassis  20 , impinges an air flow regulating plate  42   a  formed in the inside of the package cover  42  facing downward, and flows downward toward the carriage  2 . 
     In this way, by making the shape of the ceiling part of the housing cover  42  as a concave curved surface seen from the inside thereof, the air which impinges the ceiling part can effectively be led to the side of the carriage  2 . Further, as the air flow generated at the blow fan  40  is led toward the side of the carriage  2  utilizing the housing cover  42 , forming of a new path for the air flow is unnecessary, and the air flow at the rear of the chassis  20  can be led to the forward of the chassis  20  with a simple configuration. 
     Further, as the blow fan  40  is arranged on the side of the reference position of the recording head  1 , and a space covered by the housing cover  42  has a larger space compared with the side of the reference position on the opposite side (the side of the non-reference position) of the reference position relative to the traveling direction of the recording head  1 , the air which impinges the ceiling part of the housing cover  42  also flows from the side of the reference position to the side of the non-reference position, and when flowing downward toward the carriage  2 , an air flow from the side of the reference position to the side of the non-reference position is formed together with an air flow to downward. 
     The air flow from the side of the reference position to the side of the non-reference position is formed, as indicated also by the arrows D in FIG. 3, across the whole region of the width direction of the recording paper  150 . The air flow is, as indicated by an arrow C 1  in FIG. 2, mostly directed more to the downstream of the conveying direction of the recording paper  150  than to the chassis  20 , and partially, not overriding the chassis  20 , directed downward as it is, as indicated by an arrow E in FIG. 2, at a position more upstream of the conveying direction of the recording paper  150  than the chassis  20 . 
     The air flown in the direction of the arrow E is blown onto the paper feeding roller  202  of the auto sheet feeder  200  positioned at the rear of the chassis  20  (the upstream of the conveying direction of the recording paper). In this way, the dispersed ink mist is prevented from adhering to the paper feeding roller  202 . As the result, when the recording paper  150  is separated sheet by sheet from the auto sheet feeder  200  by the paper feeding roller  202 , the ink mist adhered to the paper feeding roller  202  can be prevented from being transferred to the recording paper  150 , and the surface of the recording paper  150  can be avoided of being stained by the ink mist. 
     Meanwhile, the air flown in the direction indicated by the arrow C 1  in FIG. 2, is blown to the carriage  2 , the scale  32 , the carriage shaft  3 , and respective members for conveying the recording paper  150 , namely the conveying roller  102 , the pinch roller  103 , the paper pressing plate  107 , and the like. 
     As the conveying roller  102 , the pinch roller  103 , and the paper pressing plate  107  are subjected to air blowing, these members are prevented from being adhered to by the ink mist, and similarly with the case of the above described paper feeding roller  202 , the recording paper  150  is prevented from being stained by the ink mist while the recording paper  150  is being conveyed. By the way, the pinch roller  103  is provided in a plural number in width direction of the recording paper  150  with a space between the respective rollers, and in the air flow path in this region, bumps are formed by respective pinch rollers  103 . When air is blown onto the part where the pinch rollers  103  are thus arranged, the air flow gets turbulent, and the air flow from the side of the reference position to the side of the non-reference position and the air flow from the upstream to the downstream relative to the conveying direction of the recording paper  150  are obstructed. Thereupon, in the present embodiment, the paper pressing plate  107  is made in a shape that covers all the pinch rollers  103  so that the bumps due to the pinch rollers  103  are eliminated so as to create an efficient air flow. 
     Further, as the carriage shaft  3  is subjected to air blowing, the carriage shaft  3  is prevented from ink mist being adhered thereto, and an increase in sliding load on the carriage  2  due to the adhesion of the ink mist to the carriage shaft  3  is prevented. Furthermore, as the scale  32  is subjected to air blowing, adhesion of the ink mist to the scale  32  is prevented, and faulty reading of the scale  32  by the reading sensor  31  may be prevented. As the adhesion of the ink mist to the carriage shaft  3  and the scale  32  is prevented in this way, stabilized operation and reliable position control of the carriage  2  become possible. 
     The air blown onto the carriage  2  is blown to the electrically connected section (head contact section) between the recording head  1  and the carriage  2 , the reading sensor  31 , and the discharging port surface of the recording head  1 , and then flows through respective spurs  109  to the paper expelling side of the recording paper  150  as indicated by an arrow C 2  in FIG.  2 . Thus, adhesion of the ink mist to the head contact section, reading sensor  31 , and the discharging port surface is prevented. Further, as the adhesion of the ink mist to the discharging port surface of the recording head  1  is prevented, faulty discharging of ink due to wetting, soiling, or the like of the discharging port surface is prevented. Furthermore, as the adhesion of the ink mist to the head contact section is prevented, electrical faulty connection between the recording head  1  and the carriage  2  is prevented. Further, as the adhesion of the ink mist to the reading sensor  31  is prevented, faulty position detection of the carriage  2  is prevented, and resultantly maloperation of the carriage  2  can be prevented. 
     Moreover, the air flown in a direction as indicated by the arrow C 1  in FIG. 2 is also blown onto the head recovery system unit  10 , as illustrated in FIG.  3 . The recording head  1 , at a position opposing to the head recovery system unit  10 , prior to the recording operation, or at each fixed timing, performs a preliminary discharge for discharging thickened ink in the recording head  1 , minute dust, and the like, and at this instance, ink mist is also generated. When the head recovery system unit  10  is subjected to air blowing, the ink mist generated at the time of preliminary discharge escapes to a direction indicated by the arrow C 2  in FIG. 2, and the adhesion of the ink mist to the capping mechanism and the wiping mechanism provided in the head recovery system unit  10  is prevented, thus deterioration of the discharging characteristic of the recording head  1  can be prevented. 
     Moreover, as previously described, since the discharge of the ink from the recording head  1  is performed only when the carriage  2  is traveling from the side of the reference position to the side of the non-reference position, the air flow from the side of the reference position to the side of the non-reference position, as shown by an arrow D in FIG. 3, can efficiently control the ink mist generated at the time when the ink is discharged from the recording head  1 . 
     In other words, when the carriage  2  travels from the side of the reference position to the side of the non-reference position, negative pressure is generated at the rear of the traveling direction of the carriage  2 . Although the negative pressure causes to generate an air flow which is in a direction reverse to the direction of the arrow C 2  in FIG. 2, namely an air flow directing from the outside of the ink jet recording apparatus to the inside of the reciprocal traveling region of the carriage  2 , an air flow along the traveling direction of the carriage  2  exists in the reciprocal traveling region of the carriage  2 , and the air flow negates the air flow of the direction reverse to the direction of the arrow C 2 , thereby the ink mist is prevented from being dispersed in the inside of the ink jet recording apparatus. 
     Further, as an air flow by the blow fan  40  is to be created by air introduced from the outside of the ink jet recording apparatus, fresh air is introduced into the inside of the ink jet recording apparatus. As the result, the ink mist generated in the ink jet recording apparatus ceases to circulate in the ink jet recording apparatus, and adhesion of the ink mist to the above described respective members may more effectively be prevented. 
     As described heretofore, the air flow generated by the blow fan  40  proceeds, in the end, through an interval between the paper feeding roller  108  and the spurs  109  to the direction indicated by the arrow C 2  in FIG.  2 . 
     The air flow proceeding toward the direction of the arrow C 2  is absorbed by the air flow generated from the suction fan  48 . The outline of the air flow will be described with reference to FIG.  7 . 
     On the downstream side relative to the conveying direction of the recording paper in the recording region, a region where the recording head  1  and a platen  106  opposes each other, a paper expelling unit  110  and an ink mist collecting path forming member  111  having a space for containing the ink mist are provided. In the ink mist collecting path forming member  111 , the spurs  109 , which is a rotary members for discharging paper and compose a paper expelling unit  110  (refer FIG.  2  and others), are removably provided. Moreover, in the ink mist collecting path forming member  111 , provided is a joint section  111   a  removably connected with a duct where the suction fan  48  (refer FIG.  3  and others) is provided, as later described. Because of this, air in the recording region is to be sucked via the paper expelling unit  110  and the ink mist collecting path forming member  111 . Moreover, the ink mist collecting path forming member  111  and the paper expelling unit  110  can be replaced as an integrated body or individually. 
     The air flow and the air sucking path by the above mentioned suction fan  48  will be described in detail hereunder. As illustrated in FIGS. 2 and 3, of the conveying mechanism of the recording paper  150 , the spurs  109  positioned at the dead end downstream of the conveying direction of the recording paper  150  are provided in plurality with a space between the respective spurs in width direction of the recording paper  150 , in a box-type spur base  45  having substantially the same width as the recording paper  150 . Respective spurs  109  are arranged at the upstream end of the spur base  45  relative to the conveying direction of the recording paper  150 , and on a low wall of the spur base  45 , suction ports  45   a  are formed respectively between and in the neighborhood of the respective spurs  109 . 
     The spur base  45  is one component of a replacement unit which is regularly replaced for maintenance of the ink jet recording apparatus. Therefore, in the width direction of the spur base  45 , and at the end of the opposite side relative to the head recovery system unit  10  (the end of the side of the non-reference position), a joint section  45   b  is provided as a body, and the joint section  45   b  is removably connected with a relay duct  47  via a rubber joint  46  having a sealing function. Although the tip of the relay duct  47  is secured to the chassis  20 , at the point of the chassis  20  where the relay duct  47  is secured, an aperture corresponding to the cross sectional shape of the relay duct  47  is provided, and at the aperture, the suction fan  48  for expelling the air in the spur base  45  via the relay duct  47  is provided. In other words, the suction fan  48  is arranged on the back of the chassis  20 . 
     By providing the suction fan  48  and the blow fan  40  on the back (rear) of the chassis  20  in this way, as driving noise of the suction fan  48  and the blow fan  40  is blocked by the chassis  20 , noise toward the forward of the ink jet recording apparatus can be reduced. Furthermore, as complicated mechanism needed to be positioned on the back of the chassis  20  is small in number, a large space can be secured thereat, and a blow fan  40  and a suction fan  48  can be provided without unnecessarily enlarging the size of the ink jet recording apparatus. 
     Further, on the expelling side of the suction fan  48 , a suction fan duct  49  is provided, which leads the air released from the suction fan  48  downward, as illustrated in FIG.  5 . 
     In this way, the air flowing through respective spurs  109  to the direction of the arrow C 2  is, as indicated by an arrow F in FIGS. 3 and 5, sucked from respective suction ports  45   a  into the spur base  45 , and released from the back of the ink jet recording apparatus through the relay duct  47 . 
     Although the air flowing in the direction indicated by the arrow C 2  in FIG. 2 contains ink mist, recording is completed while the air flowing in the direction of the arrow C 2 , namely toward the conveying direction of the recording paper  150 , is being sucked and adhesion of the ink mist to the recording paper  150  released on a paper expelling tray  120  is prevented. Moreover, by providing the suction ports  45   a  between the respective spurs  109 , the ink mist can be sucked at a position nearer to the recording head  1  which generates the ink mist, thus the ink mist can be efficiently sucked. Further, when the suction fan  48  is positioned on the side of the non-reference position, and the connecting section with the relay duct  47  is provided on the side of the non-reference position, an air flow from the side of the reference position toward the side of the non-reference position is created in the spur base  45 , thus the air flow from the side of the reference position toward the side of the non-reference position in the traveling region of the carriage  2  is immune from obstruction. 
     Respective suction ports  45   a  are arranged, as illustrated in FIG. 3, such that the ports positioned on the upstream side of the air flow direction in the spur base  45  is to have a larger aperture area than the ports positioned on the downstream side thereof. By this arrangement, a sufficient air sucking force relative to the air flow in the spur base  45  is generated also on the upstream side, and the path resistance in the spur base  45  may be made substantially uniform in the width direction of the spur base  45 , thus the air flow in the spur base  45  is kept substantially uniform. As the result, the ink mist is efficiently sucked across the whole region of the width direction of the recording paper  150 . 
     Moreover, by enlarging the aperture area of the suction ports  45   a  in the upstream of the air flow in the spur base  45 , namely on the side of the head recovery system unit  10 , the ink mist generated at recovery processing of the recording head  1  may be efficiently sucked, and the ink mist may be prevented from dispersing to the important members such as the capping mechanism and the wiping mechanism of the head recovery system unit  10 . 
     Moreover, as the spur base  45  is removably provided on the ink jet recording apparatus by the joint section  45   b , when the ink jet recording apparatus is used for an elongated time, ink mist sucking performance of the suction ports  45   a  is deteriorated by the ink mist deposited in the inside of the spur base  45 , or the ink mist is deposited on the spurs  109  to cause stains to be transferred onto the recording paper  150 , the spur base  45  may be easily dismounted for cleaning and replacement thereof. Furthermore, the spur base  45  may be mounted or dismounted only by inserting or drawing the joint section  45   b  into or out of the rubber joint  46 , the mounting or dismounting of the spur base  45  may be surely performed with ease. By providing in this way a sucking path for the air mixed with the ink mist in the spur base  45 , which is a component of the replacement unit, the ink jet recording apparatus may be simultaneously subjected to regular maintenance and removed of the ink mist adhered to the inside of the sucking path. By such arrangement, the ink mist dispersed in the ink jet recording apparatus may be efficiently sucked even without deteriorating the ink mist sucking efficiency throughout the sucking path. 
     As the diameters of the ink mist particles are very minute, a greater part of the ink mist sucked from the suction ports  45   a  of the spur base  45  adheres to the inner wall surface of the spur base  45  or the relay duct  47 , and the ink mist seldom escapes from the ink jet recording apparatus to the outside, but when the ink jet recording apparatus is used for an elongated time, the ink mist escaped to the outside of the ink jet recording apparatus, although very minutely at a time, may be deposited to cause staining of the outside of the ink jet recording apparatus. Thereupon, by providing a filter for picking up the ink mist at the inside of at least either of the relay duct  47  or a suction fan duct  49 , the escape of the ink mist to the outside of the ink jet recording apparatus may assuredly be prevented. 
     In the present embodiment above described, although a description is made about a case of configuration where ink mist containment members and the paper expelling unit are replaceable, the ink mist collecting path forming member  111 ′ may be provided separately from the spurs  109 ′ and the paper expelling roller  108 ′, making only the ink mist collecting path forming member  111 ′ replaceable, as illustrated in FIG.  8 . 
     Further, although an example where the blow fan  40  and the suction fan  48  are used as air flow generating means is given, in a case where the air flow generated in the reciprocal traveling region of the carriage  2  is sufficient only with the air flow from the upstream to the downstream relative to the conveying direction of the recording paper  150 , either of the blow fan  40  or the suction fan  48  may be used. 
     Furthermore, in the above, a description is made about a case where the ink discharge from the recording head  1  is performed while the carriage  2  travels from the side of the reference position to the side of the non-reference position (one-way recording), even when the recording is performed while the carriage  2  travels from the side of the non-reference position to the side of the reference position (two-way recording), substantially similar advantage is expected, as an air flow is formed from upstream to downstream of the conveying direction of the recording medium. Further, although the above description is made about the serial type ink jet recording apparatus, an ink jet recording apparatus using a line type recording head may achieve substantially similar advantage due to the same reason. 
     In the ink jet recording apparatus composed as above described, as an air sucking path having apertured air sucking ports is connected to the sucking side of the fan, the ink mist generated by discharging of the ink from the recording head is sucked by the air suction ports of the air sucking path. When an ink jet recording apparatus is used for an elongated time, the ink mist is gradually deposited in the air sucking path causing the sucking efficiency to deteriorate, but as the air sucking path is removably connected with a fan, the air sucking efficiency may be satisfactorily maintained by dismounting the air sucking path with deposited ink mist from the fan to clean or replace the air sucking path. As the result, an ink jet recording apparatus of excelled reliability capable of recording a high definition image for an elongated period of time may be provided. Specifically, by providing an air sucking path in an replacement unit, as regular maintenance of the ink jet recording apparatus may be performed simultaneously with the replacement of the air sucking path having the ink mist deposited therein, and the ink mist sucking efficiency is prevented from being deteriorated. 
     A replacement unit may include, for example, a spur unit provided with spurs composing a conveying means for conveying a recording medium together with a expelling roller at the expelling side of the recording medium. When an air sucking path is provided in the spur unit, air suction ports may be apertured between the respective spurs provided in plurality so that ink mist can be sucked at a position close to the ink mist generating section, making the ink mist sucking efficiency to improve.