JP2016094291A - Inkjet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove paper powder.SOLUTION: An inkjet recorder 1 comprises a recording head 34, a carrying part 31 and a negative pressure impression part 33. The recording head 34 discharges ink on paper P. The carrying part 31 carries the recording paper P to an image formation position by the recording head 34. The carrying part 31 also comprises a pressing roller 312 for pushing down the paper on the upstream side in the carrying direction of the paper to a plate-like member 35. The pressing roller 312 is arranged on the upstream side in the carrying direction of the paper P to the recording head 34, and presses the paper P. The negative pressure impression part 33 impresses negative pressure on a lower space of the pressing roller 312 and a lower space of the recording head 34. The negative pressure impression part 33 also impresses negative pressure stronger than the negative pressure impressed on the lower space of the recording head 34, on the lower space of the pressing roller 312.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ink jet recording apparatus.

  2. Description of the Related Art Conventionally, in an ink jet recording apparatus that discharges ink onto a recording medium, a technique for removing paper dust is known in order to suppress the occurrence of nozzle clogging in a recording head.

  For example, an ink jet recording apparatus is disclosed in which a paper dust collecting member is disposed upstream of the recording head in the conveyance direction of the recording medium (see Patent Document 1). The paper dust collecting member includes a vertical wall and a downstream side wall. The vertical wall rises vertically upward. The downstream side wall extends from the upper end of the vertical wall toward the downstream side in the conveyance direction of the recording medium.

  In Patent Document 1, paper dust generated as the recording medium is conveyed is collected by the paper dust collecting member before reaching the recording head, so that the amount of paper dust adhering to the recording head is reduced. It is stated that you can.

JP 2008-213255 A

  However, in the ink jet recording apparatus described in Patent Document 1, paper dust is not effectively removed because paper dust is attached to the paper dust collecting member and removed. Further, even if paper dust adheres to the paper dust collecting member, the adhered paper dust falls from the paper dust collecting member and, for example, adheres to the recording paper and is transported to the recording head. There is a risk of adhesion.

  The present invention has been made in view of the above problems, and an object thereof is to provide an ink jet recording apparatus capable of effectively removing paper dust.

  The ink jet recording apparatus of the present invention includes a recording head, a transport unit, a pressing roller, and a negative pressure applying unit. The recording head ejects ink onto a recording medium. The transport unit transports the recording medium to an image forming position by the recording head. The pressing roller is disposed upstream of the recording head in the conveyance direction of the recording medium and presses the recording medium. The negative pressure application unit applies a negative pressure to a space below the plurality of pressing rollers and a space below the recording head. The negative pressure application unit applies a negative pressure stronger than the negative pressure applied to the space below the recording head to the space below the pressing roller.

  According to the ink jet recording apparatus of the present invention, paper dust can be effectively removed.

It is a figure which shows the structure of the inkjet recording device which concerns on this embodiment. FIG. 2 is a diagram illustrating a configuration of an image forming unit illustrated in FIG. 1. FIG. 3 is a cut perspective view illustrating configurations of a conveyance belt, a guide member, and a negative pressure application unit illustrated in FIG. 2. It is a top view which shows the structure of the guide member shown in FIG. It is the top view and sectional drawing which show the structure of the groove | channel and through-hole which were formed in the guide member shown in FIG. (A) is a top view which shows the structure of a groove | channel and a through-hole. (B) is AA sectional drawing of the structure of the groove | channel and through-hole which are shown to (a). It is a figure which shows the structure of the plate-shaped member vicinity shown in FIG. It is a figure which shows the structure of the press roller vicinity shown in FIG. FIG. 3 is a plan view illustrating an example (first embodiment) of a configuration of a guide member having a groove and a through hole below a pressing roller and a recording head shown in FIG. 2. (A) is a top view which shows the structure of the guide member which has a groove | channel and a through-hole below a press roller. FIG. 5B is a plan view showing a configuration of a guide member having a groove and a through hole below the recording head. It is a top view which shows another example (2nd Embodiment) of the structure of the guide member which has the groove | channel and the through-hole under the press roller shown in FIG. 2, and the downward direction of a recording head. (A) is a top view which shows the structure of the guide member which has a groove | channel and a through-hole below a press roller. FIG. 5B is a plan view showing a configuration of a guide member having a groove and a through hole below the recording head. It is a figure which shows other embodiment of the negative pressure application part shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings (FIGS. 1 to 10). In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

  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 casing 100, a sheet feeding unit 2 disposed below the inside of the apparatus casing 100, an image forming unit 3 disposed above the sheet feeding unit 2, and one side of the image forming unit 3. A sheet transport unit 4 disposed on the right side in FIG. 1 and a sheet discharge unit 5 disposed on the other side (left side in FIG. 1) of the image forming unit 3 are provided.

  The paper feed unit 2 includes a paper feed cassette 21, a paper feed roller 22, and a guide plate 23. The paper feed cassette 21 stores recording paper P and is detachable from the apparatus housing 100. The paper feed roller 22 is disposed above one end (the right end in FIG. 1) of the paper feed cassette 21. The guide plate 23 is disposed between the paper feed roller 22 and the paper transport unit 4.

  A plurality of recording papers P are stored in the paper feed cassette 21. Hereinafter, “recording paper” is simply referred to as “paper” for convenience. The recording paper P corresponds to an example of “recording medium”. The paper feed roller (pickup roller) 22 is a roller that feeds the paper P along the conveyance direction of the paper P, and takes out the paper P in the paper feed cassette 21 one by one from the top. The guide plate 23 guides the paper P taken out by the paper feed roller 22 to the paper transport unit 4.

  The paper transport unit 4 includes a substantially C-shaped paper transport path 41, a first transport roller pair 42 provided on the entrance side of the paper transport path 41, a second transport roller pair 43 provided in the middle of the paper transport path 41, In addition, a registration roller pair 44 provided on the exit side of the paper conveyance path 41 is provided.

  The first transport roller pair 42 is a roller pair (feed roller pair) that feeds the paper P along the transport direction of the paper P, and sends the paper P supplied from the paper feed unit 2 to the paper transport path 41. To do. The second transport roller pair 43 is also a feed roller pair. The second transport roller pair 43 feeds the paper P sent by the first transport roller pair 42 toward the registration roller pair 44 across the paper P.

  The registration roller pair 44 performs skew correction of the paper P that has been transported by the second transport roller pair 43. In addition, the registration roller pair 44 temporarily stops the paper P in order to synchronize the timing of image formation on the paper P and the conveyance timing of the paper P, and then sets the paper P to the image formation timing. Send to forming unit 3.

  The image forming unit 3 includes a transport belt 32 and a recording head 34, and transports the paper P supplied from the registration roller pair 44 in a predetermined direction (leftward in FIG. 1) by the transport belt 32 and transports by the transport belt 32. An image is formed by the recording head 34 on the paper P being printed. The detailed configuration of the image forming unit 3 will be described later with reference to FIG. Further, the image forming unit 3 includes a conveyance guide 36 on the downstream side in the conveyance direction of the paper P (left side in FIG. 1) with respect to the recording head 34.

  The transport guide 36 guides the paper P discharged from the transport belt 32 to the paper discharge unit 5. The paper discharge unit 5 includes a discharge roller pair 51 and a discharge tray 52. The discharge tray 52 is fixed to the apparatus casing 100 so as to protrude outward from the discharge port 11 formed in the apparatus casing 100.

  The discharge roller pair 51 sends the paper P that has passed through the conveyance guide 36 toward the discharge port 11. The discharge tray 52 guides the paper P sent out by the discharge roller pair 51. The paper P sent out by the discharge roller pair 51 is discharged to the outside of the apparatus housing 100 through the discharge port 11 formed on one side surface (left side surface in FIG. 1) of the apparatus housing 100. The discharge tray 52 stacks and stores the paper P discharged from the discharge port 11.

  Next, the image forming unit 3 will be described with reference to FIG. FIG. 2 is a diagram showing the configuration of the image forming unit 3 shown in FIG.

  As shown in FIG. 2, the image forming unit 3 includes a transport unit 31, a negative pressure applying unit 33, a recording head 34, and a plate-like member 35. Each of the four types of recording heads 34a, 34b, 34c, and 34d is provided with a plurality of nozzles (not shown). Ink is ejected from the plurality of nozzles to form images such as characters and figures on the paper P. Since the recording heads 34a, 34b, 34c, and 34d have substantially the same configuration, they may be collectively referred to as the recording head 34.

  The transport unit 31 transports the paper P in a predetermined direction (leftward in FIG. 2), and includes a belt speed detection roller 311, a press roller 312, a drive roller 313, a tension roller 314, a pair of guide rollers 315, and A transport belt 32 is provided.

  The transport unit 31 is disposed in the apparatus housing 100 so as to face the four types of recording heads 34 (34a, 34b, 34c, and 34d). The conveyance belt 32 is stretched around a belt speed detection roller 311, a driving roller 313, a tension roller 314, and a pair of guide rollers 315. The transport belt 32 is driven in the transport direction of the paper P (counterclockwise in FIG. 2) and transports the paper P. The transport belt 32 corresponds to an example of an “endless belt”.

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

  The belt speed detection roller 311 is arranged on the upstream side (right side in FIG. 2) in the conveyance direction of the paper P with respect to the negative pressure application unit 33, and rotates due to the frictional force with the conveyance 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 conveyor belt 32 is detected.

  The drive roller 313 is disposed on the downstream side (left side in FIG. 1) in the transport direction of the paper P with respect to the negative pressure application unit 33. Preferably, the driving roller 313 is arranged so as to maintain the flatness of the conveyance belt 32 at a position facing the recording 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 conveying belt 32 in the counterclockwise direction of FIG.

  The pair of guide rollers 315 are disposed below the negative pressure application unit 33 and form a space below the negative pressure application unit 33. By arranging in this way, contact between the conveyance belt 32 and the negative pressure application unit 33 below the negative pressure application unit 33 can be prevented.

  The four types of recording heads 34 (34a, 34b, 34c, and 34d) are arranged in parallel from the upstream side to the downstream side in the transport direction of the paper P. Each of the recording heads 34a, 34b, 34c, and 34d includes a plurality of nozzles (not shown) arranged in the width direction of the transport belt 32 (in FIG. 2, the direction orthogonal to the paper surface). The recording heads 34a, 34b, 34c, and 34d are called a line type. That is, the ink jet recording apparatus 1 is a line head type ink jet recording apparatus.

  The plate-like member 35 is disposed upstream of the recording head 34 in the transport direction of the paper P (right side in FIG. 2). In other words, the plate-like member 35 is disposed between the recording head 34 a and the pressing roller 312. The plate member 35 is fixed to, for example, a fixing member (not shown) extending from the apparatus housing 100 shown in FIG. Specifically, the fixing member extending from the apparatus housing 100 fixes both ends of the plate-like member 35 in the width direction (direction perpendicular to the paper surface in FIG. 1). Further, the plate-like member 35 forms a narrow space 35 a between the upper surface of the transport belt 32. The plate member 35 corresponds to an example of a “space forming portion”. A space between the lower surface of the plate-like member 35 and the upper surface of the conveyor belt 32 is a narrow space 35a described later.

  The pressing roller 312 is a driven roller that is arranged on the upstream side (the right side in FIG. 2) in the transport direction of the paper P with respect to the recording head 34 and the plate-like member 35 and presses the paper P. The pressing roller 312 includes three rollers (the pressing roller 312a, the pressing roller 312b, and the pressing roller 312c). The pressing roller 312a, the pressing roller 312b, and the pressing roller 312c have the same configuration. The pressing roller 312 is arranged to face the guide member 332 via the conveyance belt 32, guides the paper P sent out from the registration roller pair 44 onto the conveyance belt 32, and attracts it to the conveyance belt 32. The pressing roller 312 is pressed against the conveyor belt 32.

  The moment of inertia of the pressing roller 312 is preferably small in order to mitigate the collision vibration generated when the paper P collides with the pressing roller 312. In other words, the pressure roller 312 is preferably light. The detailed configuration of the pressing roller 312 will be described later with reference to FIG.

  The negative pressure application unit 33 applies a negative pressure to the paper P via the transport belt 32 and causes the paper P to be attracted to the transport belt 32. Further, the negative pressure application unit 33 is disposed on the back surface side (lower side in FIG. 2) of the conveyance belt 32 so as to face the four types of recording heads 34 via the conveyance belt 32. The negative pressure application unit 33 includes an air circulation chamber 331, a guide member 332 that covers the upper surface opening of the air circulation chamber 331, a negative pressure generation unit 336, and an exhaust port 337.

  The guide member 332 supports the paper P via the transport belt 32. The guide member 332 corresponds to an example of a “conveyance plate”. Further, a through hole 335 is formed in the guide member 332. The guide member 332 is made of, for example, a metal material. Specifically, as the material of the guide member 332, an aluminum die cast, a pressed plate, or the like can be used. Alternatively, as the material of the guide member 332, a resin excellent in slidability with the transport belt 32 can be selected.

  In the present embodiment, for the sake of convenience, the negative pressure application unit 33 is described as including the guide member 332. However, as described above, the guide member 332 supports the conveyance belt 32, so the conveyance unit 31 supports the guide member 332. It may be described as provided.

  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 guide member 332. The negative pressure generator 336 is disposed below the air circulation chamber 331. On the bottom wall of the box-shaped member constituting the air circulation chamber 331, an exhaust port 337 is disposed on the downstream side (lower side in FIG. 2) of the negative pressure generating unit 336 with respect to the air flow. When the negative pressure generating unit 336 is driven, a negative pressure is generated in the air circulation chamber 331, and the negative pressure causes the paper P to be sucked toward the transport belt 32 through the guide member 332 and the transport belt 32. The

  The negative pressure generator 336 generates a negative pressure in the air circulation chamber 331, and is, for example, a fan. However, the negative pressure generator 336 is not limited to a fan, and may be a vacuum pump, for example.

  Next, the operation of the inkjet recording apparatus 1 will be described with reference to FIG. The paper feed roller 22 takes out the paper P from the paper feed cassette 21. The taken paper P is guided to the first transport roller pair 42 by the guide plate 23.

  The paper P is sent into the paper transport path 41 by the first transport roller pair 42 and is transported in the transport direction of the paper P by the second transport roller pair 43. Then, the sheet P comes into contact with the registration roller pair 44 and stops, and skew correction is performed. Then, the sheet P is sent to the image forming unit 3 by the registration roller pair 44 in accordance with the image forming timing.

  The paper P is guided onto the transport belt 32 by the pressing roller 312 and is attracted to the transport belt 32. The paper P is preferably guided to the transport belt 32 so that the center of the paper P in the width direction coincides with the center of the transport belt 32 in the width direction. The paper P covers a part of a large number of suction holes 321 (see FIG. 3) formed in the transport belt 32. The negative pressure application unit 33 sucks air through the guide member 332 and the conveyor belt 32, and a negative pressure is generated in the air circulation chamber 331. As a result, negative pressure acts on the paper P, and the paper P is attracted to the transport belt 32. The paper P is transported in the transport direction of the paper P as the transport belt 32 moves.

  Each portion of the paper P is continuously conveyed by the conveyance belt 32 to positions facing the four types of recording heads 34a, 34b, 34c, and 34d. During this time, ink of each color is ejected from the four types of recording heads 34a, 34b, 34c, and 34d toward the paper P being transported by the transport belt 32. As a result, an image is formed on the paper P.

  The paper P is transported from the transport belt 32 to the transport guide 36. The sheet P that has passed through the conveyance guide 36 is sent in the direction of the discharge port 11 by the discharge roller pair 51, guided to the discharge tray 52, and discharged to the outside of the apparatus housing 100 through the discharge port 11.

  Next, with reference to FIG. 3, the structure of the conveyance belt 32, the guide member 332, and the negative pressure application part 33 is demonstrated. FIG. 3 is a cut perspective view illustrating the configuration of the conveyance belt 32, the guide member 332, and the negative pressure application unit 33 illustrated in FIG.

  As shown in FIG. 3, the conveyance belt 32, the guide member 332, the air circulation chamber 331, and the negative pressure generation unit 336 are arranged from the upper side to the lower side. A number of suction holes 321 are formed in the transport belt 32.

  Here, the suction holes 321 formed in the transport belt 32 will be described. As shown in FIG. 3, a plurality of suction holes 321 are formed in the conveyor belt 32 at substantially equal intervals. The diameter of the suction hole 321 is, for example, 2 mm, and the distance from the adjacent suction hole 321 is, for example, 8 mm.

  In addition, a plurality of grooves 334 are formed on the upper surface of the guide member 332 (the surface on the conveying belt 32 side). The groove 334 is formed in an oval shape extending in the conveyance direction of the paper P.

  Next, the groove 334 and the through hole 335 formed in the guide member 332 will be described with reference to FIG. 4 is a plan view showing the configuration of the guide member 332 shown in FIG. As shown in FIG. 4, the guide member 332 includes a row of oval grooves 334 extending in the conveyance direction of the paper P (left and right in FIG. 4), and the width direction of the guide member 332 (up and down in FIG. 4). In the direction). In addition, a through hole 335 that penetrates the guide member 332 in the thickness direction is formed in the groove 334 at a substantially central position in the conveyance direction (left and right direction in FIG. 4) of the paper P. The cross section of the through hole 335 is circular.

  The broken line shown in FIG. 4 indicates the position of the plate-like member 35 projected onto the guide member 332. With respect to the projection image of the plate-like member 35 on the guide member 332, the through holes 335 are respectively provided on the upstream side in the transport direction of the paper P (left side in FIG. 4) and on the downstream side in the transport direction of the paper P (right side in FIG. 4). Are formed one by one. A groove 334 communicating with the through hole 335 formed on the upstream side in the transport direction of the paper P (left side in FIG. 4) is upstream in the transport direction of the paper P in the projection image of the plate-like member 35 (left side in FIG. 4). It extends further upstream in the transport direction of the paper P than the end position. Similarly, the groove 334 communicating with the through hole 335 formed on the downstream side in the transport direction of the paper P (right side in FIG. 4) is downstream in the transport direction of the paper P in the projection image of the plate member 35 (right side in FIG. 4). ) It extends further downstream in the transport direction of the paper P than the edge position.

  Next, the groove 334 and the through hole 335 formed in the guide member 332 will be described with reference to FIG. FIG. 5 is a plan view and a cross-sectional view showing the configuration of the groove 334 and the through hole 335 formed in the guide member 332 shown in FIG. 5A is a plan view showing the configuration of the groove 334 and the through hole 335, and FIG. 5B is a cross-sectional view taken along the line AA of the groove 334 and the through hole 335 shown in FIG. 5A. .

  As shown in FIG. 5A, a through hole that penetrates the guide member 332 in the thickness direction is provided at a substantially central position in the conveyance direction of paper P in the groove 334 (left-right direction in FIG. 5A). 335 is formed. As shown in FIG. 5B, since the groove 334 is formed so as to communicate with the through hole 335, the negative pressure applied from the air circulation chamber 331 via the through hole 335 forms the groove 334. It also affects the area where it is.

  Next, the configuration in the vicinity of the plate-like member 35 will be described with reference to FIG. FIG. 6 is a diagram showing a configuration in the vicinity of the plate-like member 35 shown in FIG.

  In the narrow space 35a, the velocity of the airflow flowing into the narrow space 35a from the space around the narrow space 35a is larger after flowing into the narrow space 35a than before flowing into the narrow space 35a. Thus, the distance H in the direction orthogonal to the upper surface of the conveyor belt 32 is set. In other words, the distance H is the vertical length (distance) of the narrow space 35a. Specifically, the lower surface of the plate-like member 35 is between the upper surface of the transport belt 32 and the narrow space 35a in which the vertical distance H is set to be equal to or less than a preset threshold distance HS (for example, 3 mm). Form. The plate-like member 35 is a conductor (for example, a metal such as stainless steel) having at least a lower surface thereof grounded. The upper surface of the conveyor belt 32 that is in contact with the guide member 332 corresponds to an example of a “recording medium placement surface”. In the present embodiment, the vertical distance H of the narrow space 35a is, for example, 2 mm.

  In the above description with reference to FIG. 6, the case where the thickness of the paper P is sufficiently thin as compared with the vertical distance H of the narrow space 35 a has been described. It is preferable to change the vertical distance H of the gap space 35a. Specifically, for example, the plate member 35 is moved up and down according to the thickness of the paper P so that the distance between the upper surface of the paper P and the lower surface of the plate member 35 is substantially constant (for example, 2 mm). It is preferable.

  Next, the flow of air in the vicinity of the narrow space 35a will be described. The air circulation chamber 331 is in a negative pressure state (for example, the differential atmospheric pressure with respect to the atmospheric pressure is about 0.005 atm ≈ about 500 Pa) by the negative pressure generating unit 336. Therefore, the plurality of suction holes 321 and the plurality of suction holes 321 Air flows from the narrow space 35 a into the air circulation chamber 331 through the through hole 335. Further, since air flows from the narrow space 35a into the air circulation chamber 331, the upstream side in the transport direction of the paper P with respect to the plate member 35 (the right side in FIG. 6) and the downstream side in the transport direction of the paper P Air flows into the narrow space 35a from (left side in FIG. 6).

  Therefore, air flows along the arrows FD21 and FD22 shown in FIG. Since the vertical distance H of the narrow space 35a is set to be equal to or less than the preset threshold distance HS, the wind speed in the narrow space 35a increases. The wind speed in the narrow space 35a is preferably 6.0 m / second or more, for example.

  As described above, since the wind indicated by the arrow FD21 blows from the upstream side to the downstream side in the conveyance direction of the paper P in the narrow space 35a (to the left in FIG. 6), as shown in FIG. The paper dust PD adhering to the front end (left end in FIG. 6) of the paper P can be removed, and the removed paper dust PD can be collected in the air circulation chamber 331. Further, since the wind indicated by the arrow FD22 blows from the downstream side in the conveyance direction of the paper P toward the upstream side (in the right direction in FIG. 6) in the narrow gap space 35a, as shown in FIG. The paper dust PD attached to the rear end (right end in FIG. 6) can be removed, and the removed paper dust PD can be collected in the air circulation chamber 331. Therefore, the paper dust PD adhering to the paper P can be effectively removed.

  Further, as described above, since the plate member 35 is a grounded conductor, the plate member 35 is not charged. Therefore, even when the paper dust PD is charged, the adhesion of the paper dust PD to the plate-like member 35 can be suppressed.

  Further, as described above with reference to FIG. 5, since the groove 334 is formed at a position facing the plate-like member 35, the negative pressure applied from the air circulation chamber 331 through the through hole 335 is applied to the groove 334. It also acts on the region where 334 is formed. Therefore, since air becomes easier to flow along the arrows FD21 and FD22 shown in FIG. 6, the paper dust PD can be more effectively removed.

  Next, the positional relationship between the suction hole 321 and the groove 334 will be described with reference to FIG. A plurality of rows of suction holes 321 arranged in the transport direction of the paper P are formed in the width direction of the transport belt 32 (a direction orthogonal to the transport direction of the paper P). The suction holes 321 are arranged in a staggered manner. As shown in FIG. 3, the rows of the plurality of suction holes 321 of the conveyor belt 32 are respectively arranged corresponding to the rows of the plurality of grooves 334.

  The plurality of grooves 334 are formed so as to face at least two suction holes 321, respectively. As the transport belt 32 moves, the opposing suction holes 321 are replaced one by one in the plurality of grooves 334, respectively.

  The air circulation chamber 331 that is set to a negative pressure by the negative pressure generator 336 communicates with the suction hole 321 of the transport belt 32 through the through hole 335 and the groove 334 of the guide member 332.

  As described above, since the negative pressure is applied to the suction hole 321 of the transport belt 32, the transport belt 32 can suck and transport the paper P.

  Next, a configuration near the pressing roller 312 will be described with reference to FIG. FIG. 7 is a diagram showing a configuration in the vicinity of the pressing roller 312 shown in FIG.

  The three pressing rollers 312a, the pressing roller 312b, and the pressing roller 312c are arranged close to each other. For example, when the diameter of the pressing roller 312 is 20 mm, the interval between the axial centers of the adjacent pressing rollers 312 is 23 mm. In this case, the minimum distance B1 between the peripheral surfaces of the adjacent pressing rollers 312 is 3 mm.

  In addition, a space 312 d is formed by being surrounded by the peripheral surfaces of the pressing roller 312 a and the pressing roller 312 b and the upper surface of the transport belt 32. Similarly, a space 312e is formed by being surrounded by the peripheral surfaces of the pressing roller 312b and the pressing roller 312c and the upper surface of the transport belt 32. Further, a suction hole 321 (see FIG. 3) is formed in the transport belt 32 below the pressure roller 312a, the pressure roller 312b, and the pressure roller 312c, and the through hole 335 and the groove 334 are formed in the guide member 332, respectively. Is formed.

  Next, the flow of air in the vicinity of the pressing roller 312 will be described. The air circulation chamber 331 is in a negative pressure state (for example, the differential atmospheric pressure with respect to the atmospheric pressure is about 0.005 atm ≈ about 500 Pa) by the negative pressure generating unit 336, so that the plurality of suction holes 321, the grooves 334, The air flows from the spaces 312d and 312e into the air circulation chamber 331 through the through hole 335. Further, since air flows from the spaces 312d and 312e into the air circulation chamber 331, the upstream side in the transport direction of the paper P (the right side in FIG. 7) with respect to the pressing roller 312 and the downstream side in the transport direction of the paper P ( From the left side in FIG. 7, air flows into the spaces 312d and 312e.

  Therefore, air flows along the arrows FD11 and FD12 shown in FIG. Since the minimum distances B1 and B2 between the peripheral surfaces of the adjacent pressing rollers 312 are, for example, 3 mm as described above, the wind speed of the air flowing into the spaces 312d and 312e increases. The wind speed in the spaces 312d and 312e is preferably 6.0 m / second or more, for example.

  The pressing rollers 312 (312a, 312b, 312c) press the paper P (or the conveyance belt 32) with a predetermined pressure (for example, 1.5 N). Therefore, for example, when the leading edge of the paper P enters the pressing roller 312a, the paper powder PD attached to the leading edge of the paper P adheres to the peripheral surface of the pressing roller 312a by the pressing force of the pressing roller 312a. Further, the paper dust PD adhering to the peripheral surface of the pressing roller 312a is moved from the space 312d to the air circulation chamber 331 through the suction hole 321, the groove 334, and the through hole 325 by the air flow along the arrow FD11. Collected.

  Similarly, for example, when the trailing edge of the paper P passes through the pressing roller 312b, the paper powder PD attached to the trailing edge of the paper P adheres to the peripheral surface of the pressing roller 312b by the pressing force of the pressing roller 312b. To do. Further, the paper dust PD adhering to the peripheral surface of the pressing roller 312b is transferred from the space 312e to the air circulation chamber 331 through the suction hole 321, the groove 334, and the through hole 325 by the air flow along the arrow FD12. Collected.

  As described above, since the pressing roller 312 presses the paper P, the paper dust PD adhering to the paper P adheres to the peripheral surface of the pressing roller 312. Further, below the pressing roller 312, a suction hole 321 is formed in the conveyance belt 32, and a through hole 335 and a groove 334 are formed in the guide member 332, so that the air flow along the arrows FD <b> 11 and FD <b> 12 is generated. Occur. Therefore, the paper dust PD adhering to the paper P can be effectively removed.

  Further, since the three pressing rollers 312 are arranged close to each other, the wind speed of the air flowing into the spaces 312d and 312e increases. Therefore, the paper dust PD adhering to the paper P can be more effectively removed.

  Next, the configuration of the guide member 332 having the groove 334 and the through hole 335 below the pressing roller 312 and below the recording head 34 will be described with reference to FIGS. 8 and 9. FIG. 8 is a plan view showing an example (first embodiment) of a configuration of a guide member 332 having a groove 334 and a through hole 335 below the pressing roller 312 and below the recording head 34 shown in FIG. FIG. 8A is a plan view showing a configuration of a guide member 332 having a groove 334 and a through hole 335 below the pressing roller 312. FIG. 8B is a plan view showing a configuration of a guide member 332 having a groove 334 and a through hole 335 below the recording head 34.

  As shown in FIG. 8A, two types of grooves 334 a and 334 b are formed in the guide member 332 below the pressing roller 312. The broken lines shown in FIG. 8A indicate the positions of the three pressing rollers 312 projected onto the guide member 332. The groove 334a has a width W1 (for example, 4 mm) larger than a width W2 (for example, 2 mm) of the groove 334b. The length of the groove 334a is the same as the length of the groove 334b, for example, 15 mm. In the groove 334a, a through hole 335a is formed at the center of the conveyance direction of the paper P (vertical direction in FIG. 8A). Similarly, a through hole 335b is formed at the center of the groove 334b in the transport direction of the paper P (vertical direction in FIG. 8A). The diameter D1 (for example, 4 mm) of the through hole 335a is larger than the diameter D2 of the through hole 335b (for example, 2 mm). The cross sections of the through hole 335a and the through hole 335b are circular.

  Further, as shown in FIG. 8A, a groove 334b and a through hole 335b are formed in the center portion in the width direction of the guide member 332, and a groove 334a and a through hole 335a are formed in both side end portions in the width direction. Is formed. The distance between the groove 334a, the through hole 335a, the groove 334b, and the through hole 335b in the conveyance direction (vertical direction in FIG. 8A) of the paper P is a distance L11 (for example, 23 mm).

  As shown in FIG. 8B, a groove 334 b is formed in the guide member 332 below the recording head 34. A broken line shown in FIG. 8B indicates the position of the recording head 34a projected on the guide member 332. Further, in the groove 334b, a through hole 335b is formed at the center of the conveyance direction of the paper P (vertical direction in FIG. 8B). Further, the distance between the groove 334b and the through hole 335b in the conveyance direction of the paper P is a distance L21 (for example, 30 mm).

  As described above, the conveyance direction of the sheet P in the groove 334a, the through hole 335a, the groove 334b, and the through hole 335b formed in the guide member 332 below the pressing roller 312 (vertical direction in FIG. 8A). Is narrower than the gap in the conveyance direction of the paper P in the groove 334b formed in the guide member 332 below the recording head 34 and the through-hole 335b. In other words, the distance L11 is smaller than the distance L21. Further, the groove 334 a formed in the guide member 332 below the pressing roller 312 is wider than the groove 334 b formed in the guide member 332 below the recording head 34. Further, the through hole 335 a formed in the guide member 332 below the pressing roller 312 is larger than the through hole 335 b formed in the guide member 332 below the recording head 34.

  In other words, the pressure loss from the negative pressure generating unit 336 shown in FIG. 2 to the spaces 312d and 312e below the pressing roller 312 (see FIG. 7) is the pressure loss from the negative pressure generating unit 336 to the space below the recording head 34. Through-holes 335 a and 335 b and grooves 334 a and 334 b are formed in the guide member 332 so as to be smaller. Accordingly, since a large negative pressure is applied to the spaces 312d and 312e (see FIG. 7) below the pressing roller 312, the paper powder PD adhering to the paper P can be effectively removed. In addition, since a small negative pressure is applied to the space below the recording head 34, the influence of the print quality of the recording head 34 can be suppressed.

  FIG. 9 is a plan view showing another example (second embodiment) of the guide member 332 having a groove 334 and a through hole 335 below the pressing roller 312 and below the recording head 34 shown in FIG. is there. FIG. 9A is a plan view showing a configuration of a guide member 332 having a groove 334 and a through hole 335 below the pressing roller 312. FIG. 6B is a plan view showing a configuration of a guide member 332 having a groove 334 and a through hole 335 below the recording head 34.

  As shown in FIG. 9A, a groove 334 a is formed in the guide member 332 below the pressing roller 312. The groove 334a has a width W1 (for example, 4 mm) larger than the width W2 (for example, 2 mm) of the groove 334b shown in FIG. 9B. The length of the groove 334a is the same as the length of the groove 334b shown in FIG. 9B, and is, for example, 15 mm. In the groove 334a, a through hole 335a is formed at the center of the conveyance direction of the paper P (vertical direction in FIG. 9A). The diameter (for example, 4 mm) of the through hole 335a is larger than the diameter of the through hole 335b (for example, 2 mm) shown in FIG. Moreover, the cross section of the through-hole 335a and the through-hole 335b shown in FIG.9 (b) is circular shape.

  Further, as shown in FIG. 9A, the distance between the groove 334a and the through hole 335a in the transport direction (vertical direction in FIG. 9A) of the paper P is a distance L12 (for example, 23 mm).

  As shown in FIG. 9B, a groove 334 b is formed in the guide member 332 below the recording head 34. Further, in the groove 334b, a through hole 335b is formed at the center of the conveyance direction of the paper P (vertical direction in FIG. 9B). In addition, the distance in the conveyance direction of the paper P between the groove 334b and the through hole 335b is a distance L22 (for example, 60 mm).

  As described above, the interval between the groove 334a formed in the guide member 332 below the pressing roller 312 and the conveyance direction (vertical direction in FIG. 9A) of the paper P in the through hole 335a is the recording head 34. Is narrower than the gap between the groove 334b formed in the lower guide member 332 and the through hole 335b in the conveyance direction of the paper P. In other words, the distance L12 is smaller than the distance L22. Further, the groove 334 a formed in the guide member 332 below the pressing roller 312 is wider than the groove 334 b formed in the guide member 332 below the recording head 34. Further, the through hole 335 a formed in the guide member 332 below the pressing roller 312 is larger than the through hole 335 b formed in the guide member 332 below the recording head 34.

  In other words, the pressure loss from the negative pressure generating unit 336 shown in FIG. 2 to the spaces 312d and 312e below the pressing roller 312 (see FIG. 7) is the pressure loss from the negative pressure generating unit 336 to the space below the recording head 34. Through holes 335a and 335b and grooves 334a and 334b are formed so as to be smaller. Accordingly, since a large negative pressure is applied to the spaces 312d and 312e (see FIG. 7) below the pressing roller 312, the paper powder PD adhering to the paper P can be effectively removed. In addition, since a small negative pressure is applied to the space below the recording head 34, the influence of the print quality of the recording head 34 can be suppressed.

  Next, another embodiment of the negative pressure applying unit 33 shown in FIG. 2 will be described with reference to FIG. FIG. 10 is a diagram illustrating another embodiment (negative pressure application units 33a and 33b) of the negative pressure application unit 33 illustrated in FIG. The negative pressure application units 33a and 33b are different from the negative pressure application unit 33 shown in FIG. 2 in that they include air circulation chambers 331a and 331b, respectively. The negative pressure application unit 33a corresponds to a “first negative pressure application unit”, and the negative pressure application unit 33b corresponds to a “second negative pressure application unit”. In the following description of the negative pressure application units 33a and 33b, the same components as those of the negative pressure application unit 33 shown in FIG.

  The negative pressure application unit 33a applies negative pressure to the spaces 312d and 312e (see FIG. 7) below the pressing roller 312 and the narrow space 35a. The negative pressure application unit 33a includes an air circulation chamber 331a, a negative pressure generation unit 336a, an exhaust port 337a, and a filter 338. The filter 338 removes paper dust.

  The negative pressure application unit 33 b applies a negative pressure to the space below the recording head 34. The negative pressure application unit 33b includes an air circulation chamber 331b, a negative pressure generation unit 336b, and an exhaust port 337b.

  The negative pressure application unit 33a applies negative pressure to the spaces 312d and 312e (see FIG. 7) below the pressing roller 312 and the narrow space 35a, and the negative pressure application unit 33b enters the space below the recording head 34. In order to apply a negative pressure, it is possible to apply a strong negative pressure to the spaces 312 d and 312 e below the pressure roller 312 and the narrow space 35 a and apply a weak negative pressure to the space below the recording head 34. It becomes possible. Specifically, the negative pressure generating unit 336a of the negative pressure applying unit 33a is configured such that the negative pressure in the air circulation chamber 331a is increased (for example, the rotational speed of the fan is increased), whereby the narrow space 35a. A strong negative pressure can be applied. Further, the negative pressure generating unit 336b of the negative pressure applying unit 33b is configured so that the negative pressure in the air circulation chamber 331b is reduced (for example, the fan rotation speed is decreased), so that the space below the recording head 34 is reduced. A weak negative pressure can be applied.

  Therefore, the paper dust PD can be effectively removed in the spaces 312d and 312e below the pressing roller 312 and the narrow space 35a. Further, the influence on the print quality of the recording head 34 can be suppressed.

  Further, since the negative pressure application unit 33a includes the negative pressure generation unit 336a, the negative pressure generation unit 336a causes the negative pressure of an appropriate size to be applied to the spaces 312d and 312e below the pressing roller 312 and the narrow space 35a. Can be generated. Similarly, since the negative pressure applying unit 33b includes the negative pressure generating unit 336b, the negative pressure generating unit 336b can generate a negative pressure of an appropriate magnitude in the space below the recording head 34.

  Further, the negative pressure fluctuates in accordance with the ejection of ink by the recording head 34. When the fluctuation of the negative pressure is large, the exhaust gas may flow backward. Therefore, when there is only one exhaust port (for example, in the case shown in FIG. 2), the recovered paper powder PD may be discharged from the through-hole 335 due to the backflow of exhaust. On the other hand, in the embodiment shown in FIG. 10, as described above, the negative pressure application unit 33a and the negative pressure application unit 33b include the exhaust port 337a and the exhaust port 337b, respectively, so that the exhaust gas flows backward in the negative pressure application unit 33b. In this case, the negative pressure application unit 33a is not affected. Therefore, it is possible to prevent the collected paper powder PD from being discharged from the through hole 335.

  Further, as described above, since the negative pressure application unit 33a includes the filter 338, the paper powder PD discharged from the air circulation chamber 331a can be captured.

  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 example, (1) to (7) shown below). 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.

  (1) In this embodiment, the case where the conveyance belt 32 conveys the paper P in the image forming unit 3 has been described. However, the image forming unit 3 may convey the paper P by other methods. For example, the paper P may be transported by a plurality of transport rollers. In this case, it is preferable to apply a negative pressure from between adjacent conveyance rollers.

  (2) In the present embodiment, the case where the narrow space 35a is formed by the plate-like member 35 has been described. However, the narrow space 35a may be formed by other methods. For example, the head base that supports the recording head 34 may be formed to protrude toward the conveyance belt 32 on the upstream side in the conveyance direction of the paper P with respect to the recording head 34 to form the narrow space 35a. In this case, the structure can be simplified.

  Further, instead of the plate-like member 35, the narrow space 35a may be formed by a belt stretched around two rollers. Specifically, the driving roller and the driven roller disposed at a position substantially parallel to the upper surface of the transport belt 32, and an endless belt stretched between the driving roller and the driven roller, the lower surface of the endless belt, A narrow gap space 35 a is formed between the upper surface of the conveyor belt 32. In this case, when the paper dust adheres to the lower surface of the endless belt, the endless belt can be driven to rotate so that the surface to which the paper dust does not adhere is located on the lower side. The frequency with which the man removes the paper dust adhering to the endless belt can be reduced.

  (3) In this embodiment, the case where the guide member 332 and the air circulation chamber 331 are separate members has been described. However, the guide member 332 and the air circulation chamber 331 may be integrally formed. In this case, leak of negative pressure from the air circulation chamber 331 (inflow of air into the air circulation chamber 331 from the gap between the guide member 332 and the air circulation chamber 331) can be prevented.

  (4) In this embodiment, although the case where the three press rollers 312 were arrange | positioned was demonstrated, what is necessary is just the form by which the multiple press rollers 312 are arrange | positioned. For example, two pressing rollers 312 may be arranged, or four or more pressing rollers 312 may be arranged. As the number of the pressing rollers 312 increases, the paper powder PD can be collected more effectively. The configuration can be simplified as the number of the pressing rollers 312 is smaller.

  (5) In the present embodiment, the case where the width W1 of the groove 334a is wider than the width W2 of the groove 334b has been described with reference to FIGS. 8 and 9, but the depth of the groove 334a is deeper than the depth of the groove 334b. But you can. Further, the width and depth of the groove 334a may be larger than the width and depth of the groove 334b, respectively.

  (6) In the present embodiment, the case where the exhaust port 337a of the negative pressure application unit 33a includes the filter 338 has been described with reference to FIG. 10, but the exhaust port 337b of the negative pressure application unit 33b also includes the filter 338. Good. In this case, the paper powder PD discharged from the air circulation chamber 331b can also be captured. Further, the exhaust port 337 of the negative pressure applying unit 33 shown in FIG. 2 may be provided with a filter. In this case, the paper powder PD discharged from the air circulation chamber 331 can be captured.

  (7) In the present embodiment, the case where the pressing roller 312 and the plate-like member 35 are provided has been described. However, the embodiment may include at least one of the pressing roller 312 and the plate-like member 35. In this case, the configuration is simplified.

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

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Paper feed part 3 Image formation part 31 Conveyance part 312 (312a, 312b, 312c) Press roller 312d, 312e Space 32 Conveyance belt 321 Suction hole 33, 33a Negative pressure application part 331, 331a, 331b Air circulation chamber 332 Guide member (conveyance plate)
334, 334a, 334b Groove 335, 335a, 335b Through hole 336, 336a, 336b Negative pressure generator 337, 337a, 337b Exhaust port 338 Filter 34 (34a, 34b, 34c, 34d) Recording head 35 Plate member (space formation) Part)
35a Narrow space 36 Transport guide 4 Paper transport section 5 Paper discharge section

Claims (11)

A recording head for discharging ink onto the recording medium;
A transport unit for transporting the recording medium to an image forming position by the recording head;
A pressure roller disposed on the upstream side in the conveyance direction of the recording medium with respect to the recording head and pressing the recording medium;
A negative pressure application unit that applies a negative pressure to a space below the pressing roller and a space below the recording head;
The ink jet recording apparatus, wherein the negative pressure applying unit applies a negative pressure stronger than a negative pressure applied to a space below the recording head to a space below the pressing roller. The transport unit includes an endless belt on which the recording medium is placed,
The inkjet recording apparatus according to claim 1, wherein the endless belt is formed with a plurality of holes for adsorbing the recording medium by a negative pressure by the negative pressure applying unit. The transport unit includes a transport plate that supports the endless belt,
The transport plate is formed with a plurality of through holes,
The inkjet recording apparatus according to claim 2, wherein the negative pressure application unit applies a negative pressure to a space below the pressing roller and a space below the recording head via the through hole. The conveying plate has a groove extending along the conveying direction of the recording medium on the endless belt side of the through hole.
The inkjet recording apparatus according to claim 3, wherein the negative pressure application unit applies a negative pressure to a space below the pressing roller and a space below the recording head via the through hole and the groove. . The negative pressure application unit includes a negative pressure generation unit that generates a negative pressure,
At least one of the through hole and the groove so that the pressure loss from the negative pressure generating portion to the space below the pressing roller is smaller than the pressure loss from the negative pressure generating portion to the space below the recording head. The ink jet recording apparatus according to claim 3, wherein the ink jet recording apparatus is formed. The negative pressure application unit is
A first negative pressure application unit that applies a negative pressure to the space below the pressing roller and the narrow space;
The inkjet recording apparatus according to claim 1, further comprising: a second negative pressure application unit that applies a negative pressure to a space below the recording head. The first negative pressure applying unit includes a first negative pressure generating unit that generates a negative pressure,
The second negative pressure applying unit includes a second negative pressure generating unit that generates a negative pressure,
The inkjet recording apparatus according to claim 6, wherein each of the first negative pressure generation unit and the second negative pressure generation unit includes an exhaust port.   The inkjet recording apparatus according to claim 7, wherein the exhaust duct of the first negative pressure generating unit includes a filter that removes paper dust.   The inkjet recording apparatus according to claim 1, wherein a plurality of the pressing rollers are arranged. A space forming part that forms a narrow space between the recording head and the pressing roller and the mounting surface of the recording medium in the transport unit,
In the narrow space, the velocity of the air flow flowing into the narrow space from the space around the narrow space is greater after flowing into the narrow space than before flowing into the narrow space. The inkjet recording apparatus according to any one of claims 1 to 9, wherein a distance in a direction orthogonal to the placement surface is set as described above.   The inkjet recording apparatus according to claim 10, wherein the space forming unit forms the narrow space so that a distance in a direction perpendicular to the placement surface in the narrow space is equal to or less than a preset threshold distance. .

Images