JP2016140997A - Inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device that can suppress generation of jamming due to curl of a sheet while suppressing deterioration in image quality.SOLUTION: The inkjet recording device comprises a conveying belt having a plurality of belt holes formed, a suctioning part that makes the conveying belt to suction a sheet, a driving part that drives the conveying belt and a recording head. The suctioning part has a platen 35 that supports the sheet through the conveying belt. The platen 35 has a plurality of platen grooves 351a and a plurality of platen holes 352a. The plurality of platen holes 352a are arranged outside in the vicinities of respective ends of opposing regions 11 opposing in a conveying direction D of the sheet. The opposing regions 11 are regions opposing to the recording head. The platen grooves 351a extend from upstream sides toward downstream sides of the opposing regions 11 in the conveying direction D of the sheet. In the platen grooves 351a are formed at least two platen holes 352a.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an ink jet recording apparatus.

  As a type of image forming apparatus, an ink jet recording apparatus including a recording head, a transport unit, and a suction unit is known. The recording head ejects ink onto the sheet. The conveyance unit includes a conveyance belt, and conveys the sheet below the recording head by the conveyance belt. The suction unit sucks the sheet toward the conveyance belt. The ink jet recording apparatus forms an image by ejecting ink from a recording head onto a sheet conveyed below the recording head. However, in the ink jet recording apparatus, when a partially curled sheet is conveyed below the recording head, the curled portion of the sheet may collide with the recording head and jam (sheet clogging) may occur. In order to solve this problem, a technique for suppressing the occurrence of jam due to sheet curling has been proposed.

  For example, Patent Document 1 describes an ink jet recording apparatus that suppresses the occurrence of jams caused by sheet curling by increasing the suction force below the recording head.

JP 2004-18151 A

  However, when the suction force below the recording head is increased, ink droplet landing disturbance may occur due to suction air generated below the recording head. In addition, foreign matter adhering to the sheet may fly up by the suction air and adhere to the recording head. The adhesion of foreign matter to the recording head causes non-ejection of ink droplets. Disturbance of ink droplet landing and non-ejection of ink droplets may reduce the quality of an image formed by the recording head.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet recording apparatus capable of suppressing the occurrence of a jam due to sheet curl while suppressing a decrease in image quality. .

  The ink jet recording apparatus of the present invention includes a conveyance belt, a suction unit, a drive unit, and a recording head. A plurality of belt holes are formed in the transport belt. The suction unit sucks the sheet onto the transport belt. The driving unit drives the conveyance belt to convey the sheet adsorbed on the conveyance belt in a first direction. The recording head discharges ink onto the sheet conveyed by the conveyance belt. The suction unit includes a platen that supports the sheet via the conveyance belt. The platen has a plurality of first platen grooves and a plurality of first platen holes. The first platen groove extends in the first direction. The first platen hole is disposed outside a first facing region facing the recording head. The first platen hole passes through the platen. The plurality of first platen holes include a plurality of second platen holes arranged in the vicinity of each end of the first facing region facing in the first direction. The plurality of first platen grooves include a second platen groove extending from the upstream side to the downstream side of the first facing region in the first direction. At least two second platen holes are formed in the second platen groove.

  According to the ink jet recording apparatus of the present invention, it is possible to suppress the occurrence of jam due to the curling of the sheet while suppressing the deterioration of the image quality.

1 is a diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the line head shown in FIG. 1, and its vicinity. It is a top view which shows the structure of the line head shown in FIG. It is a top view which shows the structure of the 1st conveying belt shown in FIG. It is a top view which shows the structure of the platen which concerns on Embodiment 1 of this invention. FIG. 6 is a diagram illustrating a state where a sheet contacts a recording head. FIG. 10 is a diagram illustrating another state in which a sheet contacts a recording head. It is a figure which shows the effect | action of the 2nd groove | channel, 3rd groove | channel, and 2nd through-hole which are shown in FIG. It is a top view which shows the structure of the platen which concerns on Embodiment 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings (FIGS. 1 to 9). In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

[Embodiment 1]
First, an ink jet recording apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an inkjet recording apparatus 1 according to the present embodiment. The ink jet recording apparatus 1 includes an apparatus housing 100, a sheet feeding unit 2, a first sheet conveying unit 4, a second sheet conveying unit 5, a sheet discharging unit 6, and a sheet reversing unit 7. The inkjet recording apparatus 1 further includes a first conveyance belt 32, a second conveyance belt 36, and four types of line heads 34a, 34b, 34c, and 34d. Since the four types of line heads 34a, 34b, 34c, and 34d have substantially the same configuration, they may be described as the line head 34.

  The paper feed unit 2 includes a paper feed cassette 21 and a paper feed roller 22. The paper feed cassette 21 is detachably attached to the apparatus housing 100. The paper feed cassette 21 stores a plurality of sheets S. The paper feed roller (pickup roller) 22 is arranged with respect to one end (the right end in FIG. 1) of the paper feed cassette 21. The paper feed roller 22 takes out the sheets S stored in the paper feed cassette 21 one by one from the top.

  The first sheet conveyance unit 4 extends from the sheet feeding unit 2 to the first conveyance belt 32 and conveys the sheet S taken out by the sheet feeding roller 22 to the first conveyance belt 32. The first sheet transport unit 4 includes a registration roller pair 44.

  The registration roller pair 44 performs skew correction of the sheet S conveyed by the first sheet conveying unit 4. At this time, the sheet S is temporarily stopped by the registration roller pair 44. After the sheet S temporarily stops, the registration roller pair 44 sends the sheet S to the first conveying belt 32 in synchronization with the image formation timing on the sheet S.

  The first conveying belt 32 is driven to convey the sheet S sent from the registration roller pair 44 in a predetermined direction. In FIG. 1, the first conveyor belt 32 is driven counterclockwise. As a result, the sheet S is conveyed leftward in FIG. Hereinafter, the direction in which the sheet S is conveyed by the first conveyance belt 32 is referred to as a conveyance direction D. The conveyance direction D is an example of a first direction. The sheet S is transported by the first transport belt 32 and passes through a position facing the line head 34. In the present embodiment, the first transport belt 32 is an endless belt.

  The line head 34 is disposed above the first conveyance belt 32. The line head 34 ejects ink onto the sheet S passing through the position facing the line head 34, and forms an image on the sheet S. In this embodiment, water-based ink is used as the ink. When the water-based ink is ejected onto the sheet S, there is a possibility that one side (image forming surface) of the sheet S is stretched by water contained in the ink and a part of the sheet S is curled.

  The sheet S on which the image is formed by the line head 34 is conveyed toward the second conveyance belt 36 by the first conveyance belt 32.

  The second conveying belt 36 is driven to convey the sheet S conveyed from the first conveying belt 32 to the second sheet conveying unit 5.

  The second sheet conveyance unit 5 extends from one end side (left side in FIG. 1) of the second conveyance belt 36 to the sheet discharge unit 6. The second sheet conveyance unit 5 includes a branch member 51 in the middle of the conveyance path. The branch member 51 is rotatably supported, and the conveyance destination of the sheet S is switched between the sheet discharge unit 6 and the sheet reversing unit 7 by the rotation of the branch member 51. When images are formed on both sides of the sheet S, the sheet S on which an image is formed on one side is guided to the sheet reversing unit 7. On the other hand, when images are formed on both sides of the sheet S, the sheet S on which images are formed on both sides is conveyed to the sheet discharge unit 6. When an image is formed only on one side of the sheet S, the sheet S on which the image is formed on one side is conveyed to the sheet discharge unit 6.

  The sheet discharge unit 6 includes a discharge roller pair 61 and a discharge tray 62. The discharge tray 62 is fixed to the apparatus housing 100 so as to protrude outside from the discharge port 101 formed in the apparatus housing 100.

  The discharge roller pair 61 sends the sheet S conveyed by the second sheet conveyance unit 5 toward the discharge port 101. The sheet S sent out by the discharge roller pair 61 is discharged to the outside of the apparatus housing 100 through the discharge port 101. On the discharge tray 62, the sheet S discharged from the discharge port 101 is placed.

  The sheet reversing unit 7 extends from the second sheet conveying unit 5 to the first sheet conveying unit 4. Specifically, one end of the sheet reversing unit 7 is connected to the second sheet conveying unit 5 at a position where the branch member 51 is provided. On the other hand, the other end of the sheet reversing unit 7 is connected to the first sheet conveying unit 4 before the registration roller pair 44. The sheet reversing unit 7 reverses the conveyance direction of the sheet S guided to the sheet reversing unit 7. As a result, an image is formed on the first surface of the sheet S and the second surface of the sheet S opposite to the first surface. That is, images are formed on both sides of the sheet S.

  Next, the configuration in the vicinity of the line head 34 and the line head 34 will be described with reference to FIG. FIG. 2 is a diagram showing the configuration of the line head 34 shown in FIG. 1 and the vicinity thereof.

  As shown in FIG. 2, the inkjet recording apparatus 1 further includes a drive unit 31, a suction unit 33, and a head base 37.

  The drive unit 31 is disposed below the line head 34. The drive unit 31 includes a belt speed detection roller 311, a suction roller 312, a drive roller 313, a tension roller 314, and a pair of guide rollers 315.

  The belt speed detection roller 311, the drive roller 313, the tension roller 314, and the pair of guide rollers 315 stretch the first conveyance belt 32.

  The belt speed detection roller 311 is arranged on the upstream side (right side in FIG. 2) in the transport direction D with respect to the suction unit 33, and rotates due to the frictional force with the first transport belt 32. The belt speed detection roller 311 includes a pulse plate (not shown), and the pulse plate rotates integrally with the belt speed detection roller 311. By measuring the rotational speed of the pulse plate, the rotational speed of the first conveyor belt 32 is detected.

  The suction roller 312 is a driven roller. The suction roller 312 faces the platen 35 provided in the suction unit 33 via the first conveyance belt 32. The suction roller 312 guides the sheet S sent from the registration roller pair 44 onto the first conveyance belt 32. The sheet S is preferably guided to the first transport belt 32 so that the center of the sheet S in the direction orthogonal to the transport direction D coincides with the center of the first transport belt 32 in the direction orthogonal to the transport direction D.

  The drive roller 313 is disposed on the downstream side (left side in FIG. 2) in the transport direction D with respect to the suction unit 33. Preferably, the driving roller 313 is arranged so as to maintain the flatness of the first conveying belt 32 at a position facing the line head 34 together with the belt speed detection roller 311.

  The driving roller 313 is rotationally driven by a motor (not shown), and rotates the first conveying belt 32 in the counterclockwise direction of FIG.

  The tension roller 314 applies tension to the first transport belt 32 so that the first transport belt 32 does not bend.

  The pair of guide rollers 315 are disposed below the suction part 33 and form a space below the suction part 33. By arranging in this way, contact between the first conveying belt 32 and the suction part 33 below the suction part 33 can be prevented.

  The suction unit 33 is disposed on the back side of the first transport belt 32. The suction unit 33 generates a suction force above the first transport belt 32 via the first transport belt 32. As a result, the sheet S being conveyed by the first conveyance belt 32 is attracted to the first conveyance belt 32. The suction part 33 includes an air circulation chamber 331, two suction force generation sources 336, and two ducts 337 in addition to the platen 35. The platen 35, the air circulation chamber 331, the two suction force generation sources 336, and the two ducts 337 are arranged in this order from the upper side to the lower side.

  The platen 35 covers the upper surface opening of the air circulation chamber 331 and supports the sheet S via the first conveyance belt 32. In the present embodiment, the platen 35 is made of a metal material. Specifically, as the material of the platen 35, an aluminum die cast, a pressed plate, or the like can be used. Alternatively, as the material of the platen 35, a resin excellent in slidability with the first transport belt 32 can be selected.

  The air circulation chamber 331 is formed by a bottomed cylindrical box-shaped member whose upper surface is open. The upper surface of the side wall constituting the air circulation chamber 331 is fixed to the platen 35. The two suction force generation sources 336 are respectively disposed below the air circulation chamber 331. When the two suction force generation sources 336 are driven, negative pressure is generated in the air circulation chamber 331, and air flows into the air circulation chamber 331 via the first conveyance belt 32 and the platen 35. As a result, the sheet S is sucked toward the first conveyance belt 32. The air sucked into the air circulation chamber 331 via the first conveying belt 32 and the platen 35 is discharged outside from the duct 337 via the suction force generation source 336.

  The suction force generation source 336 generates a negative pressure in the air circulation chamber 331 and is a fan in this embodiment. However, the suction force generation source 336 is not limited to a fan, and may be a vacuum pump, for example.

  The two ducts 337 are connected to the lower surfaces of the suction force generation sources 336, respectively. Air sucked by each suction force generation source 336 is discharged from each duct 337 to the outside.

  The four types of line heads 34a, 34b, 34c, and 34d are arranged in parallel on the head base 37 from the upstream side to the downstream side in the transport direction D.

  Next, the configuration of the four types of line heads 34a, 34b, 34c, and 34d will be described with reference to FIG. FIG. 3 is a plan view showing the configuration of the line head 34 shown in FIG.

  As shown in FIG. 3, the line head 34a has three recording heads 340a. Hereinafter, the three recording heads 340a may be referred to as a first recording head 341a, a second recording head 342a, and a third recording head 343a in order from the left side of FIG.

  The first recording head 341a, the second recording head 342a, and the third recording head 343a are arranged above the platen 35 in a staggered manner along the width direction of the platen 35. The width direction of the platen 35 is a direction orthogonal to the transport direction D. The width direction of the platen 35 is an example of the second direction.

  Specifically, the second recording head 342 a faces the central portion of the platen 35 in the width direction of the platen 35 and is adjacent to each of the first recording head 341 a and the third recording head 343 a in the width direction of the platen 35. The second recording head 342a is disposed on the upstream side in the transport direction D with respect to the first recording head 341a and the third recording head 343a. Further, the second recording head 342a has an overlapping portion 344 where the position of the platen 35 in the width direction overlaps with each of the first recording head 341a and the third recording head 343a. In other words, the second recording head 342a is disposed so as to partially overlap with a part of the first recording head 341a and a part of the third recording head 343a in the transport direction D. Accordingly, the first recording head 341a and the third recording head 343a also include an overlapping portion 344 that partially overlaps the second recording head 342a in the transport direction D.

  Similar to the line head 34a, the line head 34b has three recording heads 340b, the line head 34c has three recording heads 340c, and the line head 34d has three recording heads 340d. The recording head 340b, the recording head 340c, and the recording head 340d have substantially the same configuration as the recording head 340a. Further, the three recording heads 340b, the three recording heads 340c, and the three recording heads 340d are arranged in the same manner as the three recording heads 340a. Hereinafter, the respective recording heads 340a, 340b, 340c, and 340d may be referred to as recording heads 340.

  The recording head 340 has a plurality of nozzles (not shown). Ink is ejected from the nozzles of the recording head 340 toward the sheet S passing through a position facing the recording head 340. As a result, images such as characters and figures are formed on the sheet S.

  Next, the configuration of the first conveyor belt 32 will be described with reference to FIG. FIG. 4 is a plan view showing the configuration of the first conveyor belt 32 shown in FIG.

  As shown in FIG. 4, a plurality of suction holes 321 are formed in the first transport belt 32 at substantially equal intervals. Specifically, the plurality of suction holes 321 are formed along the transport direction D and the width direction of the platen 35 (a direction orthogonal to the transport direction D). The plurality of suction holes 321 are arranged in a staggered manner. The suction hole 321 passes through the first transport belt 32. In the present embodiment, the diameter of the suction holes 321 is 2 mm, and the interval between the adjacent suction holes 321 is 8 mm. The suction hole 321 is an example of a belt hole.

  Next, the configuration of the platen 35 will be described with reference to FIG. FIG. 5 is a plan view showing the configuration of the platen 35 according to the present embodiment. Specifically, FIG. 5 is a view of the platen 35 as viewed from the first conveying belt 32 side. A two-dot chain line shown in FIG. 5 indicates the first facing region 11 facing the recording head 340.

  As shown in FIG. 5, the platen 35 is formed with a plurality of first through holes 352 that are examples of first platen holes. The plurality of first through holes 352 are disposed outside the first facing region 11 along the transport direction D and the width direction of the platen 35 (a direction orthogonal to the transport direction D). That is, a plurality of rows including a plurality of first through holes 352 along the transport direction D are formed in the width direction of the platen 35. And each row | line | column which consists of several 1st through-holes 352 along the conveyance direction D is arrange | positioned so that it can communicate with the suction hole 321 of the 1st conveyance belt 32 demonstrated with reference to FIG. The cross-sectional shape of the first through hole 352 is circular. The first through hole 352 penetrates the platen 35 in the thickness direction of the platen 35. Accordingly, the first through hole 352 communicates with the air circulation chamber 331.

  The plurality of first through holes 352 include a second through hole 352a that is an example of a second platen hole. Each of the second through holes 352a is formed in the vicinity of each end of the first facing region 11 facing in the transport direction D.

  As shown in FIG. 5, the platen 35 is formed with a plurality of first grooves 351 that are examples of first platen grooves. The first groove 351 extends along the transport direction D. The plurality of first grooves 351 are arranged along the transport direction D and the width direction of the platen 35. That is, a plurality of rows made of a plurality of first grooves 351 along the transport direction D are formed in the width direction of the platen 35.

  The plurality of first grooves 351 includes a second groove 351a that is an example of a second platen groove. Each second groove 351a extends from the upstream side to the downstream side of the first facing region 11 in the transport direction D. That is, each second groove 351 a extends below the recording head 340 along the transport direction D. In addition, at least two second through holes 352a are formed in each second groove 351a.

  The plurality of second grooves 351a includes a third groove 351b that is an example of a third platen groove. The third groove 351 b extends from the upstream side of the second opposing region 12 in the transport direction D to the downstream side of the third opposing region 13. The second facing area 12 is an area facing the second recording head 342a described with reference to FIG. The second recording head 342 a is included in the line head 34 a that is located on the most upstream side in the transport direction D among the line heads 34. That is, the second facing area 12 is an area facing the recording head 340 located on the most upstream side in the transport direction D in the recording head 340. The third facing region 13 includes a region facing the first recording head 341d and a region facing the third recording head 343d. The first recording head 341 d and the third recording head 343 d are included in the line head 34 d that is located on the most downstream side in the transport direction D among the line heads 34. That is, the third facing region 13 is a region facing the recording head 340 located on the most downstream side in the transport direction D in the recording head 340. Therefore, the third groove 351b extends along the transport direction D so as to pass through a region facing the overlapping portion 344 described with reference to FIG.

  Subsequently, the operation of the second groove 351a, the third groove 351b, and the second through hole 352a will be described with reference to FIGS. FIG. 6 is a diagram illustrating a state where the sheet S is in contact with the recording head 340. FIG. 7 is a diagram illustrating another state in which the sheet S contacts the recording head 340. FIG. 8 is a diagram illustrating the operation of the second groove 351a, the third groove 351b, and the second through hole 352a illustrated in FIG.

  In the present embodiment, water-based ink is used as described above. When the water-based ink is ejected onto the sheet S, water contained in the ink is wetted, and one side (image forming surface) of the sheet S may be extended, and a part of the sheet S may be curled. The distortion of the sheet S due to curling becomes particularly large at the four corners of the sheet S.

  For example, in the configuration shown in FIGS. 6A and 6B, the groove 351 extends along the conveyance direction D below the recording head 340. Further, only one through hole 352 communicates with the groove 351. In such a configuration, contact between the sheet S and the recording head 340 is likely to occur.

  Specifically, the through hole 352 is located in the vicinity of the outer side immediately below the upstream end 340x of the recording head 340 in the transport direction D. Hereinafter, the end 340x is referred to as an upstream end 340x. Similarly, the downstream end 340y of the recording head 340 in the transport direction D is referred to as a downstream end 340y.

  An upstream end 351x of the groove 351 in the transport direction D is located upstream of the upstream end 340x of the recording head 340 in the transport direction D. In addition, the downstream end 351 y of the groove 351 in the transport direction D is located downstream of the downstream end 340 y of the recording head 340 in the transport direction D. Hereinafter, the end 351x is described as an upstream end 351x, and the end 351y is described as a downstream end 351y.

  In the configuration shown in FIGS. 6A and 6B described above, the pressure loss above the through hole 352 increases while the sheet S passes above the through hole 352, and the groove 351 is interposed. Thus, the suction force acting on the sheet S is increased. Therefore, even if curl occurs at the corner on the front end side of the sheet S conveyed by the conveyance belt 32, the contact between the front end of the sheet S and the recording head 340 hardly occurs. On the other hand, when the rear end of the sheet S passes above the through hole 352, the pressure loss above the through hole 352 is reduced, and the suction force acting on the sheet S via the groove 351 is weakened. Therefore, when the curl is generated at the corner on the rear end side of the sheet S, the contact between the rear end of the sheet S and the recording head 340 is likely to occur.

  Further, for example, also in the configuration shown in FIGS. 7A and 7B, since only one through hole 352 communicates with the groove 351, contact between the sheet S and the recording head 340 easily occurs.

  That is, in the configuration shown in FIGS. 7A and 7B, the upstream end 351x of the groove 351 is the recording head in the transport direction D, as in the configuration shown in FIGS. 6A and 6B. It is located upstream of the upstream end 340x of 340. Further, the downstream end 351 y of the groove 351 is located on the downstream side of the downstream end 340 y of the recording head 340 in the transport direction D. On the other hand, the through hole 352 is located in the vicinity of the outside directly below the downstream end 340 y of the recording head 340.

  In such a configuration, the pressure loss above the through hole 352 is small until the front end of the sheet S reaches above the through hole 352, and the suction force acting on the sheet S through the groove 351 remains weak. It becomes. For this reason, when the curl is generated in the corner on the front end side of the sheet S, the front end of the sheet S and the recording head 340 are likely to contact each other. On the other hand, while the sheet S passes over the through hole 352, the pressure loss above the through hole 352 increases, and the suction force acting on the sheet S via the groove 351 increases. Accordingly, even if curl occurs at the corner on the rear end side of the sheet S conveyed by the conveyance belt 32, the contact between the rear end of the sheet S and the recording head 340 hardly occurs.

  In contrast, in the present embodiment, as shown in FIGS. 8A and 8B, the two second through holes 352a communicate with the second groove 351a. That is, similarly to the groove 351 shown in FIGS. 6 and 7, the upstream end 351 x of the second groove 351 a is positioned upstream of the upstream end 340 x of the recording head 340 in the transport direction D. Further, the downstream end 351y of the second groove 351a is located on the downstream side of the downstream end 340y of the recording head 340 in the transport direction D. On the other hand, the second groove 351a communicates with a second through hole 352a disposed in the vicinity of the outer side immediately below the downstream end 340y of the recording head 340. Further, the second through hole 352a disposed in the vicinity of the outer side immediately below the upstream end 340x of the recording head 340 communicates with the second groove 351a.

  Therefore, in the present embodiment, when the front end of the sheet S enters the area below the recording head 340 (the first facing area 11), the upstream of the two second through holes 352a with respect to the conveyance direction D. The pressure loss above the second through hole 352a on the side increases. As a result, the suction force acting on the sheet S via the second groove 351a is increased. For this reason, even if curl occurs at the corner on the front end side of the sheet S conveyed by the first conveyance belt 32, the contact between the front end of the sheet S and the recording head 340 hardly occurs.

  Further, when the trailing edge of the sheet S moves away from the area below the recording head 340 (the first opposing area 11), the second through-hole downstream of the two second through-holes 352a with respect to the transport direction D is provided. The pressure loss above the hole 352a remains large. As a result, the suction force acting on the sheet S through the second groove 351a is maintained strong. For this reason, even if curl occurs at the corner on the rear end side of the sheet S conveyed by the first conveyance belt 32, the contact between the rear end of the sheet S and the recording head 340 hardly occurs.

  Therefore, in the present embodiment, the suction force acting on the sheet S through the second groove 351a is increased while the sheet S passes through the area below the recording head 340 (the first facing area 11). That is, while the sheet S passes over the second groove 351a, the second groove 351a maintains a strong suction force. Therefore, even if curling has occurred at the four corners of the sheet S, the sheet S is unlikely to come into contact with the recording head 340, and jamming due to curling of the sheet S can be suppressed.

  Further, according to the present embodiment, the second through-hole 352a is disposed in the vicinity of the outer side immediately below the upstream end 340x of the recording head 340 and the outer side of the recording head 340 immediately below the downstream end 340y. By disposing the second through hole 352a in this manner, the sheet S can be strongly sucked immediately below the upstream end 340x of the recording head 340. Further, the sheet S can be strongly sucked immediately below the downstream end 340y of the recording head 340. Accordingly, the sheet S can be more reliably adsorbed to the first conveyance belt 32 immediately below the upstream end 340x of the recording head 340 and directly below the downstream end 340y of the recording head 340. Therefore, the contact between the sheet S and the recording head 340 can be more reliably suppressed.

  According to the present embodiment, while the sheet S passes above the third groove 351b, the third groove 351b maintains a strong suction force similarly to the second groove 351a. Therefore, the contact between the sheet S and the recording head 340 can be suppressed even in the overlapping portion 344 of the recording head 340 described with reference to FIG.

  In the present embodiment, the first through hole 352 is not provided immediately below the recording head 340. That is, the first through hole 352 is formed only outside the first opposing region 11 described with reference to FIG. 5, and the first through hole 352 is not formed inside the first opposing region 11. For this reason, it is possible to suppress ink droplet landing disturbance and ink droplet non-ejection due to suction air.

  The ink jet recording apparatus 1 according to Embodiment 1 of the present invention has been described above. According to the present embodiment, it is possible to suppress a jam caused by curling of the sheet S while suppressing a decrease in image quality.

  In the present embodiment, the case where there are two suction force generation sources 336 has been described as an example, but the number of suction force generation sources 336 is not limited to two. One or three or more suction force generation sources 336 may be provided.

[Embodiment 2]
Next, an ink jet recording apparatus 1 according to Embodiment 2 of the present invention will be described with reference to FIGS. In the second embodiment, the configuration of the platen 35 is different from that of the first embodiment. Hereinafter, matters different from the first embodiment will be described with respect to the second embodiment, and descriptions of matters overlapping with the first embodiment will be omitted.

  As shown in FIG. 9, the plurality of second through holes 352a includes a plurality of third through holes 352b. The third through hole 352b is an example of a third platen hole. Each of the third through holes 352b is formed in the vicinity of a portion of the first facing region 11 that faces the overlapping portion 344 of the recording head 340 described with reference to FIG. Thereby, the contact between the sheet S and the recording head 340 can be suppressed at the overlapping portion 344 of the recording head 340.

  Further, as shown in FIG. 9, the plurality of second grooves 351 a are arranged only at positions facing the passing region 14 through which each end portion of the sheet S facing in the width direction of the platen 35 passes. Hereinafter, each end portion of the sheet S facing in the width direction of the platen 35 is referred to as each end portion of the sheet S.

  In the present embodiment, four passage areas 14 are set. Specifically, when the A4 size sheet S is passed vertically, that is, when the A4 size sheet S is conveyed so that the short side of the sheet S is orthogonal to the conveyance direction D, each end of the sheet S The part passes through the inner passage region 14 in the passage region 14 shown in FIG. 9. Further, when the A4 size sheet S is laterally passed, that is, when the A4 size sheet S is conveyed so that the long side of the sheet S is orthogonal to the conveyance direction D, each end of the sheet S is Of the passage areas 14 shown in FIG. Note that the width of the passage region 14 in the direction orthogonal to the conveyance direction D is set in consideration of variations in the position of the sheet S guided to the first conveyance belt 32 due to mechanical tolerances or the like. More preferably, the width of the passing region 14 is set in consideration of the fact that the positions of the four corners of the sheet S vary due to curling in order to more securely attract the four corners of the sheet S to the first conveying belt 32.

Suction force acting on the sheet S in the passage region 14, 30 N / m ² or more is desirable per unit area, 50 N / m ² or more 75N / m ² or less is more desirable. Accordingly, it is possible to further suppress the landing turbulence caused by the suction wind of the ink droplets ejected from the recording head 340 and the adhesion of foreign matter to the recording head 340. The suction force is calculated by the following formula.
Suction force = (negative pressure [Pa] of the air circulation chamber 331 when the sheet S is not adsorbed to the first conveying belt 32) × (opening ratio of the suction hole 321) / 100 [N / m ² ]

The suction force acting on the sheet S in the outside of the passage region 14, in the range smaller than the suction force acting on the sheet S in the passage region 14, per unit area 30 N / m ² or less is desirable, 3N / m ² More preferably, it is 15 N / m ² or less. Accordingly, it is possible to further suppress the landing turbulence caused by the suction wind of the ink droplets ejected from the recording head 340 and the adhesion of foreign matter to the recording head 340.

  As described above, in the present embodiment, the second groove 351a and the second through hole 352a are formed in the passage region 14 as in the first embodiment. Therefore, even if curling has occurred at the four corners of the sheet S, the sheet S is unlikely to come into contact with the recording head 340 and jamming due to the curling of the sheet S can be suppressed. Furthermore, in the present embodiment, the second groove 351a is formed only in the passage region 14. In other words, the first groove 351 is not formed in a portion of the first facing region 11 outside the passage region 14. Similarly to the first embodiment, the first through hole 352 is not formed immediately below the recording head 340. Accordingly, it is possible to further suppress the landing turbulence of the ink droplets ejected from the recording head 340 due to the suction air and the adhesion of foreign matter to the recording head 340.

  The inkjet recording apparatus 1 according to Embodiment 2 of the present invention has been described above. According to the present embodiment, it is possible to suppress the occurrence of a jam due to curling while suppressing a decrease in image quality.

  In the present embodiment, the present invention is applied to the inkjet recording apparatus 1 that forms an image on an A4 size sheet S, but the present invention is not limited to this. The present invention can also be applied to an ink jet recording apparatus capable of forming an image on a plurality of size types, for example, an A4 size sheet S and a B4 size sheet S. In this case, the passing area 14 may be set for each size type of the sheet S that can be handled by the ink jet recording apparatus.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For ease of understanding, the drawings schematically show each component as a main component, and the thickness, length, number, etc. of each component shown in the drawings are different from the actual for convenience of drawing. There is a case. Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the structure of this invention.

  For example, in the embodiment of the present invention, the case where the platen 35 and the air circulation chamber 331 are separate members has been described, but the platen 35 and the air circulation chamber 331 may be integrally formed. In this case, a negative pressure leak from the air circulation chamber 331 can be prevented. Specifically, the inflow of air into the air circulation chamber 331 from the gap between the platen 35 and the air circulation chamber 331 can be prevented.

  The present invention is applicable to an ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 31 Drive part 32 1st conveyance belt 321 Suction hole 33 Suction part 340 Recording head 35 Platen 351 Groove 352 Through-hole

Claims (5)

A conveyor belt formed with a plurality of belt holes;
A suction section for adsorbing the sheet to the conveyor belt;
A driving unit that drives the conveying belt to convey the sheet adsorbed on the conveying belt in a first direction;
A recording head that discharges ink onto the sheet conveyed by the conveyance belt;
The suction unit has a platen that supports the sheet via the conveyor belt,
The platen is
A plurality of first platen grooves extending in the first direction;
A plurality of first platen holes disposed outside the first facing region facing the recording head and penetrating the platen;
The plurality of first platen holes include a plurality of second platen holes disposed in the vicinity of each end of the first facing region facing in the first direction,
The plurality of first platen grooves include a second platen groove extending from the upstream side to the downstream side of the first facing region in the first direction,
The inkjet recording apparatus, wherein at least two second platen holes are formed in the second platen groove.
2. The ink jet recording apparatus according to claim 1, wherein the second platen groove is disposed in a passing region through which each end portion of the sheet facing in a second direction orthogonal to the first direction passes.
A plurality of the recording heads arranged in a staggered manner in a second direction orthogonal to the first direction;
The first facing region is
A second facing region facing the recording head located on the most upstream side in the first direction among the plurality of recording heads;
A third facing region facing the recording head located on the most downstream side in the first direction,
The platen has a plurality of the second platen grooves,
The plurality of second platen grooves include a third platen groove extending from the upstream side of the second opposing region to the downstream side of the third opposing region in the first direction. 2. An ink jet recording apparatus according to 1.
A plurality of the recording heads arranged in a staggered pattern in the second direction;
Each of the plurality of recording heads has an overlapping portion where the recording head adjacent in the second direction overlaps the position in the second direction;
The second platen groove is disposed only in the passage region,
The inkjet recording apparatus according to claim 2, wherein the plurality of second platen holes include a third platen hole disposed in the vicinity of the overlapping portion.
A sheet reversing unit for reversing the conveying direction of the sheet;
The sheet reversing unit ejects the ink onto the second surface of the sheet opposite to the first surface by the recording head after the ink is ejected onto the first surface of the sheet. The inkjet recording apparatus according to claim 1, wherein the conveyance direction of the sheet is reversed as described above.

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