Patent Publication Number: US-11383538-B2

Title: Sheet conveying device and inkjet recording apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2019-188415 filed on Oct. 15, 2019, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a sheet conveying device that conveys a sheet downstream of an inkjet unit and an inkjet recording apparatus including the same. 
     The inkjet recording apparatus includes an inkjet unit that forms an image on a sheet by discharging ink. The sheet conveying device disposed downstream in the sheet conveying direction with respect to the inkjet unit may convey the sheet, on which an ink image that has not been sufficiently dried is formed, further downstream. 
     In addition, in the inkjet recording apparatus, it is known that the sheet conveying device includes a conveying roller and a plurality of rowel-shaped driven rotating bodies. 
     The rowel-shaped driven rotating body has a plurality of convex portions and a plurality of concave portions alternately arranged along an entire circumference of an outer edge. The plurality of convex portions are in contact with a surface of the sheet on which the ink image is formed. Thus, the driven rotating body is driven to rotate with respect to the movement of the sheet. 
     Since the rowel-shaped driven rotating body has a small area of contact with the sheet, the rowel-shaped driven rotating body is less likely to adversely affect the ink image that is not sufficiently dried. 
     It is also known that the plurality of driven rotating bodies are supported by one elastic shaft in the form of a coil spring. In this case, the plurality of driven rotating bodies are urged toward the conveying roller by the elastic shaft. 
     SUMMARY 
     A sheet conveying device according to one aspect of the present disclosure includes a conveying roller configured to convey a sheet having an image formed on a first surface of the sheet by discharged ink and a plurality of driven rotating units. The conveying roller includes a first shaft supported at a position along a first direction and driven to rotate, and a plurality of roller portions that are disposed at positions opposite to the plurality of driven rotating units, respectively, are fixed to the first shaft, and rotate in contact with a second surface of the sheet opposite with the first surface to convey the sheet in a second direction orthogonal to the first direction. Each of the plurality of roller portions has three or more annular grooves. The three or more annular grooves are each provided over an entire circumference of each roller portion, and are arranged side by side in the first direction. Each of the plurality of driven rotating units includes a second shaft supported at a position along the first direction and urged toward the plurality of roller portions, and three or more driven rotating bodies disposed at positions opposite to the three or more annular grooves, respectively, and rotatably supported by the second shaft. A plurality of convex portions and a plurality of concave portions are alternately provided over an entire circumference of an outer edge of each of the three or more driven rotating bodies. Each of the three or more driven rotating bodies is driven to rotate with respect to movement of the sheet by the plurality of convex portions coming into contact with the first surface of the sheet. The three or more driven rotating bodies in each driven rotating unit include two first rotating bodies positioned at both ends in the first direction and one or more second rotating bodies located between the two first rotating bodies in the first direction and having an outer diameter smaller than the outer diameter of the two first rotating bodies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating a configuration of an inkjet recording apparatus according to an embodiment. 
         FIG. 2  is a front view of a relay sheet conveying device in the inkjet recording apparatus according to the embodiment. 
         FIG. 3  is a front view of a driven rotating unit and a roller portion in the relay sheet conveying device of the inkjet recording apparatus according to the embodiment. 
         FIG. 4  is a side view of a substrate portion of a driven rotating body in the relay sheet conveying device of the inkjet recording apparatus according to the embodiment. 
         FIG. 5  is a front view of three driven rotating bodies in the relay sheet conveying device of the inkjet recording apparatus according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that the following embodiment is an example in which the present disclosure is embodied, and does not limit the technical scope of the present disclosure. 
     [Configuration of Inkjet Recording Apparatus  10 ] 
     An inkjet recording apparatus  10  according to an embodiment is a printer capable of performing a printing process by an inkjet method. The printing process is a process of forming an image on a sheet  9 . The sheet  9  is a sheet-like image forming medium such as paper or a resin film. 
     The inkjet recording apparatus  10  may be a facsimile apparatus, a copier, a multifunction peripheral or the like capable of executing the printing process by an inkjet method. 
     As shown in  FIG. 1 , the inkjet recording apparatus  10  includes a sheet storage portion  12 , a sheet conveying apparatus  2 , an inkjet unit  3 , an ink supply unit  4 , and a controller  8 . The inkjet unit  3  includes a plurality of ink heads  31 . 
     The sheet conveying apparatus  2 , the inkjet unit  3 , the ink supply unit  4 , and the controller  8  are housed in a housing  11  that forms a main body of the inkjet recording apparatus  10 . 
     The sheet storage portion  12  can store a plurality of sheets  9 . The sheet conveying apparatus  2  conveys the sheets  9  stored in the sheet storage portion  12  one by one along an upstream conveying path  201  and a downstream conveying path  202 , and further discharges the sheets  9  from the downstream conveying path  202  to a discharge tray  13 . The upstream conveying path  201  and the downstream conveying path  202  are sheet conveyance paths. 
     The sheet conveying apparatus  2  includes a sheet feeding portion  21 , a plurality of upstream conveying roller pairs  22 , a main conveying unit  23 , a downstream conveying unit  24 , a relay sheet conveying device  25 , and a discharge roller pair  26 . The sheet feeding portion  21  feeds the sheets  9  one by one from the sheet storage portion  12  to the upstream conveying path  201 . The relay sheet conveying device  25  is an example of the sheet conveying device of the present disclosure. 
     The plurality of upstream conveying roller pairs  22  take over the conveyance of the sheet  9  from the sheet feeding portion  21  and convey the sheet  9  toward the main conveying unit  23 . 
     The main conveying unit  23  is disposed below the inkjet unit  3 . The main conveying unit  23  conveys the sheet  9  while causing the first surface of the sheet  9  to face the inkjet unit  3 . The first surface of the sheet  9  is a surface on which an ink image is formed. In the following description, a surface of the sheet  9  opposite with the first surface is referred to as “second surface”. 
     In the main conveying unit  23 , a plurality of stretching rollers  231  support and rotate an endless main conveying belt  230 . Thus, the main conveying unit  23  conveys the sheet  9  toward the downstream conveying unit  24  while placing the sheet  9  on the main conveying belt  230 . 
     The inkjet unit  3  forms the ink image on the first surface of the sheet  9  by discharging inks of a plurality of colors toward the sheet  9  conveyed by the main conveying unit  23 . 
     In the downstream conveying unit  24 , a plurality of stretching rollers  241  support and rotate an endless downstream conveying belt  240 . As a result, the downstream conveying unit  24  conveys the sheet  9  on which the ink image is formed toward the relay sheet conveying device  25  while placing the sheet  9  on the downstream conveying belt  240 . 
     The inkjet recording apparatus  10  further includes a heater  5  disposed above the downstream conveying belt  240 . The heater  5  dries the ink image on the sheet  9  by heating the first surface of the sheet  9  conveyed from the main conveying unit  23 . 
     The relay sheet conveying device  25  takes over the conveyance of the sheet  9  after image formation conveyed from the downstream conveying unit  24 , and conveys the sheet  9  further downstream along the downstream conveying path  202 . The downstream conveying path  202  is the sheet conveyance path, which extends from the relay sheet conveying device  25  to the discharge roller pair  26 . 
     As shown in  FIGS. 1 and 2 , the relay sheet conveying device  25  includes a conveying roller  27  and a plurality of driven rotating bodies  281 . The plurality of driven rotating bodies  281  are elastically urged toward the conveying roller  27  by a spring  73 . 
     The conveying roller  27  and the plurality of driven rotating bodies  281  convey the sheet  9 , on the first surface of which an image is formed by discharging ink, by rotating while holding the sheet  9  between the conveying roller  27  and the driven rotating bodies  281 . 
     As shown in  FIGS. 3 and 4 , the driven rotating bodies  281  each include a rowel-shaped substrate portion  2811  and a molded resin portion  2812  formed integrally with the substrate portion  2811 . 
     For example, the molded resin portion  2812  is a synthetic resin member molded by insert molding using the metal substrate portion  2811  as an insert article. It is also conceivable that the molded resin portion  2812  is integrally combined with the substrate portion  2811  after being molded. 
     As shown in  FIG. 4 , a plurality of convex portions  2811   a  and a plurality of concave portions  2811   b  are alternately arranged along the entire circumference of the outer edge of the substrate portion  2811 . In  FIG. 4 , the molded resin portion  2812  integrated with the substrate portion  2811  is shown by an imaginary line (two-dot chain line). 
     The plurality of convex portions  2811   a  come into contact with the first surface of the sheet  9  on which the ink image is formed. Thus, the driven rotating bodies  281  are driven to rotate with respect to the movement of the sheet  9 . 
     Since the rowel-shaped substrate portion  2811  of the driven rotating body  281  has a small area of contact with the sheet  9 , the substrate portion  2811  is less likely to adversely affect the ink image that is not sufficiently dried. 
     The discharge roller pair  26  discharges the sheet  9  conveyed from the relay sheet conveying device  25  to the discharge tray  13 . 
     The controller  8  is a device including a processor that executes various types of data processing and control. The controller  8  controls the sheet conveying apparatus  2 , the inkjet unit  3 , and the ink supply unit  4 . 
     Meanwhile, when the plurality of driven rotating bodies  281  are supported by one elastic shaft, the posture of each of the driven rotating bodies  281  may be unstable and the conveyance of the sheet  9  may be unstable. 
     Further, when all the driven rotating bodies  281  are supported by a single shaft having high rigidity, the plurality of driven rotating bodies  281  cannot be individually displaced in accordance with the flexibility of the sheet  9 , and the driven rotating bodies  281  may damage the sheet  9 . 
     On the other hand, the plurality of driven rotating bodies  281  may be individually supported and urged by the same number of support shafts and springs as the driven rotating bodies  281 . In this case, the number of components increases, and a great deal of time and effort is required to assemble the support shafts and the springs. 
     Since the relay sheet conveying device  25  has the structure shown in  FIGS. 2 to 5 , the relay sheet conveying device  25  stably conveys the sheet  9  with a relatively small number of components and with less damage to the sheet  9 . 
     [Relay Sheet Conveying Device  25 ] 
     Hereinafter, a more specific configuration of the relay sheet conveying device  25  will be described with reference to  FIGS. 2, 3, and 5 . 
     In the following description, the longitudinal direction of the conveying roller  27  in the relay sheet conveying device  25  is referred to as “first direction D 1 ”, and the direction in which the relay sheet conveying device  25  conveys the sheet  9  is referred to as “second direction D 2 ”. The second direction D 2  is a direction orthogonal to the first direction D 1 . 
     The relay sheet conveying device  25  includes the conveying roller  27  and a plurality of driven rotating units  28  that convey the sheet  9 , on the first surface of which an image is formed by discharging ink. In the example shown in  FIG. 2 , the relay sheet conveying device  25  includes four driven rotating units  28 . 
     Each of the driven rotating units  28  includes three or more driven rotating bodies  281 . For example, the number of the driven rotating bodies  281  in each of the driven rotating units  28  is three or four. In the example shown in  FIG. 2 , each of the driven rotating units  28  includes three driven rotating bodies  281 . 
     The conveying roller  27  includes a first shaft  271  and a plurality of roller portions  272 . The first shaft  271  is a hard member mainly made of metal such as iron. 
     The first shaft  271  is present over a range including a range through which the sheet  9  passes in the first direction D 1 . The first shaft  271  is disposed at a position along the first direction D 1 , is supported by a conveying roller support portion  6 , and is driven to rotate by a motor and a gear device (neither illustrated). 
     The plurality of roller portions  272  are disposed at positions opposite to the plurality of driven rotating units  28 , respectively. The plurality of roller portions  272  are fixed to the first shaft  271 . The plurality of roller portions  272  are formed integrally with the first shaft  271 . In the example shown in  FIG. 2 , four roller portions  272  are provided to face the four driven rotating units  28 . 
     Therefore, the conveying roller  27  includes the same number of roller portions  272  as the driven rotating units  28 . In other words, the relay sheet conveying device  25  includes the same number of driven rotating units  28  as the roller portions  272 . 
     The plurality of roller portions  272  convey the sheet  9  in the second direction D 2  by rotating in contact with the second surface of the sheet  9  opposite with the first surface. 
     Each of the roller portions  272  is an elastic member mainly made of rubber, an elastomer resin or the like. A particle coating is applied to the outer peripheral surface of each of the roller portions  272 . The particle coating is formed, for example, by spraying ceramic particles having an outer diameter of about 100 micrometers. 
     Each of the roller portions  272  has three or more annular grooves  2721 . The annular grooves  2721  are each provided over the entire circumference of the relevant roller portion  272  and are arranged side by side in the first direction D 1 . Each of the roller portions  272  has the same number of annular grooves  2721  as the driven rotating bodies  281  in each of the driven rotating units  28 . In the example shown in  FIGS. 2 and 3 , each of the roller portions  272  has three annular grooves  2721 . 
     In the following description, the pitch in the first direction D 1  of the three or more annular grooves  2721  in each of the roller portions  272  is referred to as “groove pitch P 1 ” (see  FIG. 3 ). 
     Each of the driven rotating units  28  includes the three or more driven rotating bodies  281 , a second shaft  282 , and a unit base  283 . The second shaft  282  is a hard member mainly made of metal such as iron. 
     The second shaft  282  is disposed at a position along the first direction D 1  and is supported by the unit base  283 . The unit base  283  is a support that supports the second shaft  282 . A shaft hole  2810  through which the second shaft  282  passes is formed in the center of the driven rotating bodies  281  (see  FIG. 4 ). 
     The driven rotating bodies  281  are disposed at positions opposite to the annular grooves  2721 , respectively. The driven rotating bodies  281  are each rotatably supported by the second shaft  282 . The driven rotating bodies  281  each include the substrate portion  2811  and, accordingly, the plurality of convex portions  2811   a  and the plurality of concave portions  2811   b  alternately arranged along the entire circumference of the outer edge (see  FIG. 4 ). 
     The relay sheet conveying device  25  further includes the conveying roller support portion  6  that supports the first shaft  271 , and a unit support device  7  that supports the unit base  283  in a swingable manner. 
     The unit support device  7  includes a third shaft  71 , a shaft support portion  72 , and the spring  73 . The third shaft  71  swingably supports the unit base  283 . That is, the unit base  283  is swingable about the third shaft  71  along the direction in which the unit base  283  moves away from and toward the conveying roller  27 . 
     The spring  73  is an elastic member that elastically urges the unit base  283  toward the conveying roller  27 . That is, the spring  73  elastically urges the second shaft  282  toward the conveying roller  27  via the unit base  283 . In other words, the spring  73  elastically urges the entire driven rotating unit  28  toward the conveying roller  27 . 
     In each of the driven rotating units  28 , the three or more driven rotating bodies  281  include two first rotating bodies  281   a  located at both ends in the first direction D 1  and one or more second rotating bodies  281   b  (see  FIGS. 2, 3, and 5 ). The one or more second rotating bodies  281   b  are positioned between the two first rotating bodies  281   a  in the first direction D 1 . 
     In the example shown in  FIGS. 2, 3, and 5 , the number of driven rotating bodies  281  in each driven rotating unit  28  is three. Therefore, each of the driven rotating units  28  includes one second rotating body  281   b.    
     If the number of the driven rotating bodies  281  in each of the driven rotating units  28  is four, the number of the second rotating bodies  281   b  in each of the driven rotating units  28  is two. 
     As shown in  FIG. 5 , a second outer diameter DM 2 , which is the outer diameter of the second rotating body  281   b , is smaller than a first outer diameter DM 1 , which is the outer diameter of the first rotating body  281   a.    
     Here, a pitch in the first direction D 1  of the three or more driven rotating bodies  281  in each of the driven rotating units  28  is referred to as “rowel pitch P 2 ” (see  FIG. 5 ). The rowel pitch P 2  is equal to the groove pitch P 1 . For example, the groove pitch P 1  and the rowel pitch P 2  are each deemed to be 5 mm to 11 mm. 
     In each of the driven rotating units  28 , the molded resin portion  2812  serves as a spacer that maintains a constant pitch of the driven rotating bodies  281  in the first direction D 1 . In each of the driven rotating units  28 , the three or more driven rotating bodies  281  are independently rotatable with respect to the second shaft  282 . 
     The groove pitch P 1  and the rowel pitch P 2  may equally be 5 mm to 11 mm. In that case, the difference between the first outer diameter DM 1  and the second outer diameter DM 2  may be 3.5% to 5.5% of the rowel pitch P 2 . 
     In the relay sheet conveying device  25 , one roller portion  272  and about three or four driven rotating bodies  281  hold a part of the sheet  9  between the roller portion  272  and the driven rotating bodies  281 . In each of the driven rotating units  28 , about three or four driven rotating bodies  281  are rotatably supported by the single second shaft  282  which is hard. 
     About three or four driven rotating bodies  281  supported by the second shaft  282  move in substantially the same manner within a relatively large range in the first direction D 1 . Further, about three or four driven rotating bodies  281  press the sheet  9  toward the annular grooves  2721 , respectively, so that the sheet  9  is curved to form a ridge line along the second direction D 2 . Thus, the sheet  9  is stably conveyed. 
     However, in the case where about three or four driven rotating bodies  281  supported by the single second shaft  282  are identical in outer diameter, a pressure similar to the pressure of the two first rotating bodies  281   a  is further applied by the second rotating body or bodies  281   b  to the portion of the sheet  9 , to which portion a tension is applied by the contact with the first rotating bodies  281   a . In this case, the second rotating body or bodies  281   b  may damage the sheet  9 . 
     Actually, in the relay sheet conveying device  25 , the outer diameter of the second rotating body  281   b  is smaller than the outer diameter of the first rotating body  281   a . Thus, the second rotating body  281   b  does a reduced damage to the sheet  9 . 
     In each of the driven rotating units  28 , the plurality of driven rotating bodies  281  are independently rotatable with respect to the second shaft  282 . Accordingly, either of the first rotating body  281   a  and the second rotating body  281   b  is prevented from rubbing against the first surface of the sheet  9  due to the difference in outer diameter. 
     In addition, in the relay sheet conveying device  25 , the plurality of driven rotating bodies  281  are unitized in units of about three or four, and the second shaft  282  supports about three or four driven rotating bodies  281 . Therefore, the relay sheet conveying device  25  is realized with a relatively small number of components.