Patent Publication Number: US-2023146622-A1

Title: Inkjet recording apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-181 077 filed on November 5. 2021. the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to an inkjet recording apparatus. 
     Inkjet recording apparatuses which record images by ejecting ink from nozzles provided in a recording head are widely used, as recording devices such as facsimile machines, copiers, and printers, for their ability to record high-definition images. 
     SUMMARY 
     According to one aspect of the present disclosure, an inkjet recording apparatus includes a sheet conveyance portion, a pair of registration rollers, a recording portion, a plate portion, a suction roller, and an exhaust portion. The sheet conveyance portion includes an endless conveyance belt and conveys a sheet. The pair of registration rollers feeds the sheet toward the sheet conveyance portion. The recording portion is disposed opposite the outer circumferential surface of the conveyance belt, includes a recording head ejecting ink, and records an image by ejecting the ink to the sheet conveyed by the conveyance belt. The plate portion is adjacent to, upstream of, the recording portion with respect to the sheet conveyance direction, is disposed opposite the outer circumferential surface of the conveyance belt, and extends in the sheet conveyance direction and in the sheet width direction orthogonal to the sheet conveyance direction. The suction roller is adjacent to, upstream of, the plate portion with respect to the sheet conveyance direction, is disposed opposite the outer circumferential surface of the conveyance belt, and brings the sheet into contact with the outer circumferential surface of the conveyance belt. The exhaust portion is disposed over an area from upstream of the recording portion to upstream of the pair of registration rollers with respect to the sheet conveyance direction and sucks air from above the conveyance belt and the plate portion in the direction away from the conveyance belt. The recording portion includes a recording portion housing. The recording portion housing holds the recording head and has an air inlet, an exhaust outlet, and an air flow passage disposed between the air inlet and the exhaust outlet, adjacent to the recording head. The exhaust portion includes an exhaust hood and an exhaust fan. The exhaust hood extends in the sheet conveyance direction and in the sheet width direction from upstream of the recording portion to upstream of the pair of registration rollers with respect to the sheet conveyance direction and covers above the conveyance belt, the plate portion, the suction roller, and the pair of registration rollers. The exhaust fan guides the air in the exhaust hood through the air inlet into the recording potion housing and then passes the air through the exhaust outlet to discharge the air via the air flow passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic sectional front view of an inkjet recording apparatus according to one embodiment of the present disclosure. 
         FIG.  2    is a top view around a recording portion in the inkjet recording apparatus in  FIG.  1   . 
         FIG.  3    is a block diagram showing the schematic configuration of the inkjet recording apparatus in  FIG.  1   . 
         FIG.  4    is a part sectional front view around the recording portion in the inkjet recording apparatus in  FIG.  1   . 
         FIG.  5    is a part sectional front view of an upstream side, in the sheet conveyance direction, around the recording portion in  FIG.  4   . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following description. 
       FIG.  1    is a schematic sectional front view of an inkjet recording apparatus  1  according to an embodiment.  FIG.  2    is a top view around a recording portion  5  in the inkjet recording apparatus  1  in  FIG.  1   .  FIG.  3    is a block diagram showing a schematic configuration of the inkjet recording apparatus  1  in  FIG.  1   . The inkjet recording apparatus  1  is, for example, an inkjet recording printer. The inkjet recording apparatus  1  includes, as shown in  FIGS.  1 ,  2 , and  3   , an apparatus main body  2 , a sheet feed portion  3 , a sheet conveyance portion  4 , a recording portion  5 . a drying portion  6 , and a control portion  7 . 
     The sheet feed portion  3  is disposed in a lower part of the apparatus main body  2 . The sheet feed portion  3  stores a plurality of sheets (a recording medium) S and, during recording, separates and feeds out the sheets S one by one. The sheet conveyance portion  4  conveys a sheet S fed out from the sheet feed portion  3  to the recording portion  5  and then to the drying portion  6  and then, after recording and drying, discharges the sheet S to a sheet discharge portion  21 . When duplex recording is performed, the sheet conveyance portion  4  distributes the sheet S after recording and drying on the first side to a reversing conveyance portion  43  and then conveys the sheet S having its conveyance direction switched and having its obverse and reverse sides reversed back to the recording portion  5  and the drying portion  6 . 
     The sheet conveyance portion  4  includes a first belt conveyance portion  41  and a second belt conveyance portion  42 . The first and second belt conveyance portions  41  and  42  convey the sheet S in a state held by suction on the outer circumferential surfaces (top surfaces) of the first and second conveyance belts  411  and  421  respectively, which are each formed in an endless shape. The first belt conveyance portion  41  is disposed below the recording portion  5  to convey the sheet S. The second belt conveyance portion  42  is located downstream of the first belt conveyance portion  41  in the sheet conveyance direction, and is disposed in the drying portion  6  to convey the sheet S. 
     The recording portion  5  is disposed opposite the outer circumferential surface (top surface) of the first conveyance belts  411 . That is, the recording portion  5  faces the conveying sheet S conveyed in a state held by suction on the outer circumferential surface (top surface) of the first conveyance belt  411 . The recording portion  5  is disposed above the first conveyance belt  411 , at a predetermined interval from it. 
     The recording portion  5  holds head units  51 B,  51 C,  51 M, and  51 Y corresponding to four colors, namely black, cyan, magenta, and yellow respectively. The head units  51 B,  51 C,  51 M, and  51 Y are arranged side by side along the sheet conveyance direction Dc so that the longitudinal direction is parallel to the sheet width direction Dw, which is orthogonal to the sheet conveyance direction Dc. The four head units  51 B,  51 C,  51 M, and  51 Y have a similar basic configuration, and accordingly hereinafter, unless necessary, the suffixes “B”, “C”, “M”, and “Y” for distinction may be omitted in the following description. 
     The head units  51  for the different colors each include line inkjet recording heads  52 . In each of the head units  51  for the different colors, a plurality of recording heads  52  (for example, three ( 52   a .  52   b ,  52   c )) are arranged in a staggered array along the sheet width direction Dw. 
     The recording head  52  includes a plurality of ink ejection nozzles  521  at its bottom. The plurality of ink ejection nozzles  521  are arranged in rows along the sheet width direction Dw so as to be able to eject ink over the entire recording area on the sheet S. That is, the recording head  52  includes a plurality of ink ejection nozzles  521  which ejects ink onto the sheet S. The recording portion  5  ejects ink sequentially from the recording heads  52  of the head units  51 B,  51 C,  51 M, and  51 Y corresponding to the four colors to the sheet S conveyed in a state held by suction on the first conveyance belt  411  and records a full-color or monochrome image on the sheet S. 
     The drying portion  6  is disposed downstream of the recording portion  5  in the sheet conveyance direction Dc and includes the second belt conveyance portion  42 . While the sheet having the ink image recorded on it in the recording portion  5  is being conveyed in a state held by suction on the second conveyance belt  421  in the drying portion  6 , the ink is dried. 
     The control portion  7  includes a CPU, a storage portion, and other electronic circuits and components (of which none are illustrated). Based on control data and programs stored in the storage portion, the CPU controls the operation of different components in the inkjet recording apparatus  1  to perform processes related to the functions of the inkjet recording apparatus  1 . The sheet feed portion  3 , the sheet conveyance portion  4 , the recording portion  5 , and the drying portion  6  individually receive instructions from the control portion  7  and performs recording on the sheet S in coordination. 
       FIG.  4    is a part sectional front view around the recording portion  5  in the inkjet recording apparatus  1  in  FIG.  1   .  FIG.  5    is a part sectional front view of the upstream side, in the sheet conveyance direction Dc, around the recording portion  5  in  FIG.  4   . A hollow broken line arrow in  FIGS.  4  and  5    indicates an airflow, along with its direction, that is caused when an exhaust portion  11 , which will be described later, is driven. 
     The recording portion  5  includes a recording portion housing  53 . The recording portion housing  53  is formed, for example, in the shape of a substantially rectangular parallelepiped box extending in the sheet conveyance direction Dc and in the sheet width direction Dw. The recording portion housing  53  holds and stores the head units  51  inside. That is, the recording portion housing  53  holds the recording heads  52 . 
     The bottom face of the recording portion housing  53  faces the sheet conveyance surface of the first conveyance belt  411 . The bottom faces of the recording heads  52 , which have a plurality of ink ejection nozzles  521 , are exposed to the outside at the bottom face of the recording portion housing  53 . The recording portion housing  53  includes an air inlet  53   a , an exhaust outlet  53   b , and an air flow passage  53   c . 
     The air inlet  53   a  is disposed in an upstream end part, in the sheet conveyance direction Dc, of the recording portion housing  53 . The air inlet  53   a  opens the recording portion housing  53  in the sheet conveyance direction Dc. The exhaust outlet  53   b  is disposed in a downstream end part, in the sheet conveyance direction Dc, of the recording portion housing  53 . The exhaust outlet  53   b  opens the recording portion housing  53  in the sheet conveyance direction Dc. 
     The air flow passage  53   c  is located between the air inlet  53   a  and the exhaust outlet  53   b . The air flow passage  53   c  is located, for example, above the recording heads  52 , is disposed adjacent to the recording heads  52 , and extends in the sheet conveyance direction Dc. In the air flow passage  53   c , air flows from the air inlet  53   a  to the exhaust outlet  53   b . 
     As shown in  FIGS.  4  and  5   , the sheet conveyance portion  4  further includes a pair of registration rollers  45 , a sheet suction portion  46 , and a suction roller  47 . 
     The pair of registration rollers  45  is disposed downstream of the sheet feed portion  3  in the sheet conveyance direction Dc. Closely downstream of the pair of registration rollers  45  in the sheet conveyance direction Dc, the first belt conveyance portion  41  and the recording portion  5  are disposed. Each roller in the pair of registration rollers  45  is supported rotatably about a rotation axis extending along the sheet width direction Dw (see  FIG.  2   ). 
     The sheet S fed out from the sheet feed portion  3  reaches the pair of registration rollers  45  via the sheet conveyance portion  4 . The control portion  7  makes the pair of registration rollers  45  correct skewed feeding of the sheet S and, in coordination with ink ejection operation by the recording unit  5 , feeds the sheet S toward the first belt conveyance portion  41 . That is, the pair of registration rollers  45  corrects skewed feeding of the sheet S and feeds out the sheet S toward the first belt conveyance portion  41 . 
     The sheet conveyance portion  4  includes a registration sensor (not illustrated). The registration sensor is closely upstream of the pair of registration rollers  45  in the sheet conveyance direction Dc. The registration sensor detects the sheet S which is fed out from the sheet feed portion  3  and reaches the pair of registration rollers  45 . Based on a detection signal regarding the sheet S received from the registration sensor, the control portion  7 , controls the rotation of the pair of registration rollers  45 . 
     The first belt conveyance portion  41  is disposed below the recording portion  5 . The first belt conveyance portion  41  sucks and holds the sheet S on its top surface and conveys the sheet S along the sheet conveyance direction Dc. The first belt conveyance portion  41  includes the first conveyance belt  411  and a roller  412 . 
     The first conveyance belt  411  is an endless belt and is wound around a plurality of rollers  412  disposed at the inner circumferential side. The rollers  412  are disposed at the inner circumferential side of the first conveyance belt  41   1  and are supported rotatably about a rotation axis extending along the sheet width direction Dw (see  FIG.  2   ). One of the plurality of rollers  412  is a driving roller and the first conveyance belt  411  is rotated by the driving roller so that its upper side moves in the sheet conveyance direction Dc. 
     As shown in  FIG.  2   , the first conveyance belt  411  has a plurality of air holes  4111 . The air holes  4111  penetrates the first conveyance belt  411  from its obverse to reverse side. The outer circumferential surface of the first conveyance belt  411  is the sheet conveyance surface. The sheet S is held on the sheet conveyance surface of the first conveyance belt  41   1  and is conveyed to a position that faces the recording heads  52 . 
     The sheet suction portion  46  is disposed at the inner circumferential side of the first conveyance belt  411 . More specifically, the sheet suction portion  46  is located in an upper part at the inner circumferential side of the first conveyance belt  411  and is disposed opposite the inner circumferential surface (obverse surface) of the upper side of the first conveyance belt  411 , that is, its surface opposite from the sheet conveyance surface. The sheet suction potion  46  includes a housing  461  and an air suction fan  462 . 
     The housing  461  is formed, for example, in the shape of a substantially rectangular parallelepiped box and has a suction chamber  4611  surrounded by walls . The suction chamber  4611  faces the inner circumferential surface (obverse surface) of the upper side of the first conveyance belt  411 , that is, its surface opposite from the sheet conveyance surface, over an area from below upstream of the black head unit  51 B in the sheet conveyance direction Dc to below the yellow head unit  51 Y. 
     The housing  461  includes a plurality of air suction holes  4612  disposed in its top face, over the suction chamber  4611 . The plurality of air suction holes  4612  penetrates the top surface of the housing  461  in the up-down direction. 
     The air suction fan  462  is disposed inside the housing  461 , in a lower part of a suction chamber  4611 . When the air suction fan  462  is driven, the sheet suction portion  46 , by sucking air through the air suction holes  4612  and the air holes  4111  (see  FIG.  2   ), sucks and holds the sheet S on the sheet conveyance surface of the first conveyance belt  411 . 
     The suction roller  47  is disposed upstream of the recording portion  5  in the sheet conveyance direction Dc, closely upstream of a plate portion  8 , which will be described later. The suction roller  47  is disposed in an upstream end part of the sheet suction portion  46 , opposite the sheet conveyance surface of the first conveyance belt  411 . In other words, the suction roller  47  is disposed above an upstream end part of the housing  461  in the sheet conveyance direction Dc, across the first conveyance belt  411 . The suction roller  47  is supported rotatably about a rotation axis extending along the sheet width direction Dw (see  FIG.  2   ). 
     The outer circumferential surface of the suction roller  47  lies in contact with the sheet conveyance surface of the first conveyance belt  411 . The suction roller  47 , for example by staying in contact with the first conveyance belt  411 , rotates so as to follow the first conveyance belt  411 . The suction roller  47  brings the sheet S conveyed from the pair of registration rollers  45  into contact with the sheet conveyance surface of the first conveyance belt  411 . 
     The inkjet recording apparatus  1  includes the plate portion  8  shown in  FIGS.  4  and  5   . The plate portion  8  is disposed adjacent to the upstream side of the recording portion  5  in the sheet conveyance direction Dc. The plate portion  8  is disposed opposite the sheet conveyance surface of the first conveyance belt  411  at the downstream side of the suction roller  47 . In other words, the plate portion  8  is disposed above the upstream part in the sheet conveyance direction Dc of the housing  461  with the first conveyance belt  411  interposed therebetween. 
     The plate portion  8  is disposed above the first conveyance belt  411 , at a predetermined interval from it. The plate portion  8  extends in the sheet conveyance direction Dc and the sheet width direction Dw (see  FIG.  2   ). The plate portion  8 . for example, extends parallel to the sheet conveyance surface of the first conveyance belt  411 . 
     The inkjet recording apparatus  1  includes an exhaust portion  11  shown in  FIGS.  4  and  5   . The exhaust portion  11  is disposed over an area from upstream of the recording portion  5  in the sheet conveyance direction Dc to upstream of the pair of registration rollers  45 . The exhaust portion  11  is placed above the sheet conveyance path. The exhaust portion  11  faces, at its air suction side, the sheet conveyance surface of the first conveyance belt  411 . that is, the sheet S conveyed along the first conveyance belt  411 . The exhaust portion  11  includes an exhaust hood  111 , an exhaust fan  112 , and a paper dust collection filter  113 . 
     The exhaust hood  111  extends in the sheet conveyance direction Dc and in the sheet width direction Dw, from upstream of the recording portion  5  in the sheet conveyance direction Dc to upstream of the pair of registration rollers  45 . The exhaust hood  111  covers above the first conveyance belt  411 , the plate portion  8 , the suction roller  47 , and the pair of registration rollers  45 . 
     Specifically, the exhaust hood  111  includes, for example, an upper plate  111   a  and a side plate  11  1b. The upper plate  111   a  extends in the sheet conveyance direction Dc and in the sheet width direction Dw, upstream from a point adjacent to an upstream end part of the recording portion  5  in the sheet conveyance direction Dc\, and extends downward with a curve over an area from above the pair of registration rollers  45  upstream. The side plate  111   b  is connected to each of a front end part and a rear end part of the upper plate  111   a  in the sheet width direction (at the near side and at the far side in the depth direction with respect to the plane of  FIG.  5   ). The side plate  111   b  extends downward from an edge part of the upper plate  111   a  in the sheet width direction Dw, in the up-down direction and in the sheet conveyance direction Dc. 
     The exhaust fan  112  is connected to a downstream end part of the exhaust hood  111  in the sheet conveyance direction Dc. The exhaust hood  111  opens, at a part of it connected to the exhaust fan  112 , in the sheet conveyance direction Dc. The air suction side of the exhaust fan  112  faces upstream in the sheet conveyance direction Dc and faces the internal space of the exhaust hood  111 . A plurality of exhaust fans  112  may be arranged in rows in the sheet width direction Dw. The exhaust fan  112  is configured with, for example, an axial fan, though it may be a centrifugal fan such as a sirocco fan or a turbo fan. The exhaust fan  112  sucks the air in the exhaust hood  111  along the sheet conveyance direction Dc. 
     The exhaust fan  112  is placed upstream of the recording portion  5  in the sheet conveyance direction Dc. The exhaust fan  112  guides the air in the exhaust hood  111  through the air inlet  53   a  into the recording potion housing  53 . The exhaust fan  112  then discharges the air guided through the air inlet  53   a  into the recording portion housing  53  through the exhaust outlet  53   b  via the air flow passage  53   c . 
     The paper dust collection filter  113  is arranged at least at one of the air inlet  53   a  side and the exhaust outlet  53   b  side of the recording portion housing  53 . In the embodiment, the paper dust collection filter  113  is disposed at the air inlet  53   a  side of the recording portion housing  53 . Thus, it is possible to make it difficult for paper dust to enter the air flow passage  53   c  located above the recording heads  52 . The paper dust collection filter  113  collects paper dust in the airflow generated by the exhaust fan  112 . 
     When the exhaust portion  11  is driven, the exhaust portion  11  sucks air upward with respect to the first conveyance belt  411 . In other words, the exhaust portion  11  sucks air from above the first conveyance belt  411  and the plate portion  8  into the exhaust hood  111  in the direction away from the first conveyance belt  411 . The exhaust portion  11  then directs the air in the exhaust hood  111  into the recording potion housing  53 , pass it through the air flow passage  53   c , and discharges it. 
     With the above configuration, the exhaust portion  11  sucks and discharges, along with air, paper dust on the first conveyance belt  411  over an area upstream of the recording portion  5  in the sheet conveyance direction Dc and paper dust floating above the first conveyance belt  411  and the plate portion  8 . Thus, it is possible to effectively remove paper dust flying from the sheet S. Additionally, by circulating the air for removing paper dust through the recording portion housing  53 , it is possible to suppress an unintended rise in the temperature of the recording heads  52 . In this way, it is possible to suppress ejection failure of the recording heads  52  caused by paper dust and a rise in the temperature of the recording heads  52 . 
     At the exhaust side of the recording portion housing  53 , for example, an exhaust duct (not illustrated) that extends to the external wall of the apparatus main body  2  is provided. 
     Specifically, the exhaust fan  112  is disposed adjacent to the air inlet  53   a  of the recording portion housing  53 . upstream of it in the air flow direction. The paper dust collection filter  113  is disposed upstream or downstream of the exhaust fan  112  in the air flow direction. In the embodiment, the paper dust collection filter  113  is disposed upstream of the exhaust fan  112  in the air flow direction. 
     With the above configuration, it is possible to suck and discharge paper dust along with air efficiently over an area from upstream of the recording portion  5  in the sheet conveyance direction Dc to upstream of the pair of registration rollers  45 . Thus, it is possible to remove paper dust flying from the sheet S more effectively. It is also possible to prevent paper dust from flowing into the recording portion housing  53  and to prevent paper dust from sticking to the exhaust fan  112 . 
     During image recording, the control portion  7  rotates the exhaust fan  112  at a first rotation speed. By contrast, during non-image recording, the control portion  7  rotates the exhaust fan  112  at a second rotation speed, which is lower than the first rotation speed. 
     During image recording, that is, when a sheet S is being conveyed, paper dust is likely to fly; thus, by rotating the exhaust fan  112  at the first, higher, rotation speed, it is possible to effectively remove paper dust flying from the sheet S. By contrast, during non-image recording, that is, when no sheet S is being conveyed, paper dust does not fly; thus, by rotating the exhaust fan  112  at the second, lower, rotation speed, it is possible to perform only the cooling of the recording heads  52 . It is thus possible to reduce the power consumption of the inkjet recording apparatus  1 . 
     When the control unit  7  detects the inkjet recording apparatus  1  being shut down, it keeps the exhaust fan  112  rotating for a predetermined period of time and then stops it. The recording heads  52  may still heat up even after the inkjet recording apparatus  1  is shut down. Thus, with this configuration, after the inkjet recording apparatus  1  is shut down, it is possible to cool the recording heads  52  with the exhaust fan  112 . 
     The inkjet recording apparatus  1  includes a temperature detection portion  12  (see  FIG.  3   ). The temperature detection portion  12  is configured with, for example, a thermistor or the like and is disposed close to the exterior of the apparatus main body  2 . The detection portion  12  detects the ambient air temperature around the inkjet recording apparatus  1 . A detection signal as to the ambient air temperature from the temperature detection portion  12  is transmitted to the control portion  7 . 
     When the ambient air temperature detected by the temperature detection portion  12  is less than a predetermined value, the control portion  7  rotates the exhaust fan  112  during image recording and, stops the rotation of the exhaust fan  112  during non-image recording. Cooling the recording heads  52  more than necessary may change the characteristics of ink and may lead to degraded image quality. Thus, with this configuration, when the ambient air temperature is less than the predetermined value, it is possible to prevent the recording heads  52  from being overcooled during non-image recording. 
     In the configuration described above, the recording heads  52  are configured with line inkjet recording heads. This makes it possible to effectively remove paper dust flying from the sheet S onto the line inkjet recording heads and to suppress ejection failure caused by paper dust. The recording heads are not limited to the line type and the configuration of the embodiment can be applied even to a serial type. 
     While an embodiment of the present disclosure has been described above, it is not meant to limit the scope of the present disclosure, which thus encompasses any modifications made without departure from the scope and sense equivalent to those claims.