JP2016129982A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the adhesion of paper powders to a recording head.SOLUTION: An ink jet recording device 1 is equipped with a recording head 34; a carrying portion 31; a first power supply portion 371; and a second power supply portion 351. The recording head 34 discharges ink onto recording paper P. The carrying portion 41 carries the recording paper P to an image forming position by the recording head 34. The first power supply portion 371 applies voltage on the recording paper P on an upstream side in a carrying direction of the recording paper P to the recording head 34. The first power supply portion 371 applies voltage of the same polarity as an electrification polarity of the recording head 34 on the recording paper P. The second power supply portion 351 includes a platy member 35 disposed between the recording head 34 and the first power supply portion 371, and applies voltage of a reverse polarity from the first power supply portion 371 on the platy member 35.SELECTED DRAWING: Figure 6

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 of the present invention is to provide an ink jet recording apparatus capable of suppressing adhesion of paper dust to a recording head.

  The ink jet recording apparatus of the present invention includes a recording head, a transport unit, a first voltage applying unit, and a second voltage 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 first voltage application unit applies a voltage to the recording medium on the upstream side in the transport direction of the recording medium with respect to the recording head. The second voltage applying unit includes a space forming unit disposed between the recording head and the first voltage applying unit, and has a polarity opposite to that of the first voltage applying unit on a lower surface of the space forming unit. Apply voltage. The first voltage application unit applies a voltage having the same polarity as the charging polarity of the recording head to the recording medium. The space forming unit forms a narrow space between the recording unit and the mounting surface of the recording medium.

  According to the ink jet recording apparatus of the present invention, adhesion of paper dust to the recording head can be suppressed.

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 which shows the structure of the groove | channel and through-hole in (a). It is a figure which shows the structure of the plate-shaped member 35 vicinity shown in FIG. It is a perspective view which shows an example of the 1st electrode and 2nd electrode which are shown in FIG. It is a figure which shows an example of the change of the charging condition of the paper dust and recording paper by the 1st electrode shown in FIG. 6, and a recording paper. (A) shows the paper dust and the charged state of the recording paper when the leading edge of the recording paper passes under the first electrode, and (b) shows the leading edge of the recording paper under the central part of the plate-like member. The paper dust and the charged state of the recording paper at the time of arrival are shown. It is a figure which shows another example of the change of the charging condition of the paper dust and recording paper by the 1st electrode shown in FIG. 6, and a recording paper. (A) shows the paper dust and the charged state of the recording paper when the leading edge of the recording paper reaches below the downstream end of the plate-like member in the paper conveyance direction, and (b) shows the recording paper at the leading edge of the recording paper. The paper dust and the charged state of the recording paper when reaching below the head are shown.

  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.

  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, a plate-like member 35, a first electrode 37, and a second electrode 38. 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 suction 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 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 suction roller 312 is a driven roller. The suction roller 312 is disposed to face the guide member 332 via the transport belt 32, guides the paper P sent from the registration roller pair 44 onto the transport belt 32, and causes the transport belt 32 to suck the paper P.

  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. The guide member 332 is grounded.

  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. An exhaust port 337 is arranged 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.

  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 suction roller 312. 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”.

  The first electrode 37 is an electrode that is disposed on the upstream side in the transport direction of the paper P (the right side in FIG. 2) with respect to the plate-like member 35 and charges the paper P and the paper powder PD. The second electrode 38 is disposed between the recording head 34 a and the plate member 35, and neutralizes the paper P charged by the first electrode 37. Details of the first electrode 37 and the second electrode 38 will be described with reference to FIGS. The first electrode 37 corresponds to a part of the “first voltage application unit”, the plate member 35 corresponds to a part of the “second voltage application unit”, and the second electrode 38 corresponds to the “first voltage application unit”. This corresponds to a part of the “three voltage application unit”.

  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 suction 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. 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 illustrating the configuration of the groove 334 and the through hole 335, and FIG. 5B is a cross-sectional view taken along the line AA illustrating the configuration of the groove 334 and the through hole 335 in FIG. 5A. It is.

  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 positional relationship between the suction holes 321 formed in the transport belt 32 and the grooves 334 formed in the guide member 332 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, 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). 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 with respect to the atmospheric pressure (for example, the differential pressure from the atmospheric pressure is about 0.005 atm≈about 500 Pa) by the negative pressure generating unit 336. Air flows from the narrow space 35a into the air circulation chamber 331 through the hole 321 and the plurality of through holes 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 arrows FD1 and FD2 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, the wind indicated by the arrow FD1 blows from the upstream side to the downstream side in the conveyance direction of the paper P in the narrow space 35a (leftward in FIG. 6). 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 FD2 blows from the downstream side to the upstream side in the conveyance direction of the paper P in the narrow gap space 35a (to the right in FIG. 6), 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.

  Furthermore, as described above with reference to FIG. 6, 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 FD1 and FD2 shown in FIG. 6, the paper dust PD can be more effectively removed.

  In addition, as shown in FIG. 6, a first power supply unit 371, a second power supply unit 351, and a third power supply unit 381 are installed. The first power supply unit 371 applies a voltage having the same polarity as the charging polarity of the recording head 34 to the paper P via the first electrode 37. Specifically, when the recording head 34 is negatively charged, the first power supply unit 371 uses, for example, −2.2 kV as a reference with respect to the guide member 332 grounded to the first electrode 37. Apply voltage. In this case, the paper P and the paper powder PD are charged to, for example, −70V.

  The second power supply unit 351 applies a voltage having a polarity opposite to that of the first power supply unit 371 to the plate member 35. Specifically, when the recording head 34 is negatively charged, the second power supply unit 351 has a voltage of, for example, +3.0 kV with respect to the guide member 332 grounded to the plate member 35. Apply. As a result, the plate member 35 is positively charged.

  As described above, since the paper dust PD is negatively charged and the plate-like member 35 is positively charged, the paper dust PD is adsorbed to the plate-like member 35 by Coulomb force. Therefore, the paper powder PD can be more effectively removed.

  Further, as described above, most of the paper dust PD adhering to the leading edge of the paper P and the trailing edge of the paper P is collected in the air circulation chamber 331 by the wind indicated by the arrow FD1 and the wind indicated by the arrow FD2. Some paper dust PD is not collected in the air circulation chamber 331. For example, in the central portion of the paper P, the paper P closes the groove 334 (through hole 335), and the wind indicated by the arrow FD1 and the wind indicated by the arrow FD2 are less likely to be generated. On the other hand, the paper dust PD adhering to the central portion of the paper P is adsorbed to the plate-like member 35 by the Coulomb force, so that the paper dust PD can be more effectively removed.

  The third power supply unit 381 applies a voltage having a polarity opposite to that of the first power supply unit 371 to the paper P via the second electrode 38. Specifically, when the recording head 34 is negatively charged, the third power supply unit 381 uses, for example, a voltage of +3.0 kV with respect to the guide member 332 grounded to the second electrode 38. Apply. In this case, the paper P and paper powder PD are neutralized. In other words, the electric charges of the paper P and the paper powder PD that charge the paper P and the paper powder PD to −70 V move to the grounded guide member 332.

  Therefore, even when the paper dust PD is conveyed to the lower side of the recording head 34, the paper dust PD is not charged, so that it can be prevented from adhering to the recording head 34 due to Coulomb force. Therefore, it is possible to effectively prevent the paper dust PD from adhering to the recording head 34.

  In the present embodiment, the case where the third power supply unit 381 neutralizes the paper P will be described. However, the third power supply unit 381 further sets the potential of the paper P to the same level as the potential of the recording head 34. preferable. When the potential of the paper P is about the same as the potential of the recording head 34, it is possible to further reliably prevent the paper dust PD from adhering to the recording head 34 due to the Coulomb force. Therefore, it is possible to more effectively suppress the paper dust PD from adhering to the recording head 34.

  The recording head 34 is negatively charged when a nozzle surface (not shown) formed on the recording head 34 is covered with fluorine. In this case, the third power supply unit 381 applies, for example, a voltage of +2.5 kV to the second electrode 38 so that the sheet P has a potential approximately equal to the potential of the recording head 34 (for example, −40 V). Apply.

  Next, with reference to FIG. 7, the needle electrode which comprises the 1st electrode 37 and the 2nd electrode 38 which are shown in FIG. 6 is demonstrated. FIG. 7 is a perspective view showing an example of the first electrode 37 and the second electrode 38 shown in FIG. Since the first electrode 37 and the second electrode 38 have substantially the same configuration, the first electrode 37 will be described for convenience. As shown in FIG. 7, the first electrode 37 is a so-called “needle electrode”.

  Specifically, the first electrode 37 includes a base body 37a and a discharge part 37b. The base 37a is a flat plate member made of a metal such as stainless steel. The discharge part 37b is disposed at the lower end of the base 37a (the end close to the guide member 332), and the tip (the end close to the guide member 332) is pointed like a needle. Yes. The base body 37a and the discharge part 37b are integrally formed.

  Moreover, the discharge part 37b is formed in substantially equal intervals, and the space | interval LN of the adjacent discharge part 37b is 4 mm, for example. In addition, a recess 37c for supporting the first electrode 37 is formed in the base body 37a. Further, the distance LA between the discharge portions 37b formed at both ends of the base 37a is set to be equal to or larger than the width of the maximum size paper P that can be printed by the inkjet recording apparatus 1.

  As described above, since the first electrode 37 and the second electrode 38 are needle electrodes, the paper powder PD and the paper P can be charged efficiently.

  In the present embodiment, the case where the first electrode 37 and the second electrode 38 are needle electrodes will be described, but other types of electrodes may be used. For example, the first electrode 37 and the second electrode 38 may be driven rollers that are driven in contact with the transport belt 32. In this case, the paper powder PD and the paper P can be more efficiently charged because they are energized in contact with the paper P.

  Next, with reference to FIGS. 8 and 9, changes in the charged state of the paper dust PD and the paper P and the movement of the paper dust PD as the paper P is transported in the transport direction will be described. FIG. 8 is a diagram illustrating an example of changes in the charged state of the paper powder PD and the paper P by the first electrode 37 and the second electrode 38 illustrated in FIG. 6. FIG. 8A shows the charged state of the paper dust PD and the paper P when the leading edge of the paper P passes under the first electrode 37, and FIG. 8B shows the leading edge of the paper P as a plate-like member. The charged state of the paper dust PD and the paper P when reaching below the central portion of 35 is shown. FIG. 9 is a diagram showing another example of changes in the charged state of the paper dust PD and the paper P by the first electrode 37 and the second electrode 38 shown in FIG. FIG. 9A shows the charged state of the paper powder PD and the paper P when the leading edge of the paper P reaches below the downstream end of the plate-like member 35 in the paper transport direction, and FIG. The charged state of the paper dust PD and the paper P when the leading edge of the paper P reaches below the recording head 34a is shown. This will be described below in the order of FIGS. 8A, 8B, 9A, and 9B.

  As described with reference to FIG. 6, for example, a voltage of −2.2 kV is applied to the first electrode 37 with reference to the grounded guide member 332. For example, a voltage of +3 kV is applied to the plate-like member 35 with reference to the grounded guide member 332. For example, a voltage of +3.0 kV is applied to the second electrode 38 with reference to the grounded guide member 332.

  FIG. 8A shows the charged state of the paper dust PD and the paper P when the leading end of the paper P (the left end in FIG. 8A) passes under the first electrode 37. In this embodiment, the paper powder PD and the paper P before reaching below the first electrode 37 are not charged. In other words, the charging polarity PV1 of the paper P before reaching below the first electrode 37 is uncharged (± 0). When passing under the first electrode 37, the paper dust PD and the paper P are negatively charged by the first electrode 37. Negatively charged paper dust PD is referred to as paper dust PDM. The charging polarity PV2 of the paper P that has passed under the first electrode 37 is negative. In FIGS. 8 and 9, the sheet P is negatively charged with a minus sign in a circle on the upper surface of the sheet P.

  FIG. 8B shows the charged state of the paper dust PD and the paper P when the leading edge of the paper P reaches below the center portion of the plate-like member 35. The negatively charged paper dust PDM is attracted to the positively charged plate member 35 by the Coulomb force and adheres to the plate member 35. On the other hand, since no discharge occurs between the plate-like member 355 and the guide member 332, the charged state of the paper P does not change. In other words, the charging polarity PV2 of the paper P that has reached below the central portion of the plate-like member 355 remains negative.

  FIG. 9A shows the charged state of the paper powder PD and the paper P when the leading edge of the paper P reaches below the downstream end of the plate-like member 35 in the paper transport direction. Similarly to FIG. 8B, the negatively charged paper dust PDM is attracted to the positively charged plate-like member 35 by the Coulomb force and adheres to the plate-like member 35. On the other hand, the charged state of the paper P does not change, and the paper P remains negatively charged.

  FIG. 9B shows the charged state of the paper powder PD and the paper P when the leading edge of the paper P reaches below the recording head 34a. When passing under the second electrode 38, the paper powder PD and the paper P are neutralized by the second electrode 38. In other words, the charging polarity PV3 of the paper powder PD and the paper P that have passed through the second electrode 38 is uncharged (± 0).

  As described above, the paper dust PD is negatively charged by the first electrode 37 and is attracted to the positively charged plate-like member 35 by the Coulomb force, and therefore adheres to the plate-like member 35. Therefore, paper dust PD can be efficiently removed.

  Further, the sheet P is negatively charged by the first electrode 37 and then discharged by the second electrode 38. Therefore, even when the paper dust PD is conveyed to the lower side of the recording head 34, the paper dust PD is not charged, so that it can be prevented from adhering to the recording head 34 due to Coulomb force. Therefore, it is possible to effectively prevent the paper dust PD from adhering to the recording head 34.

  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 (3) 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. The head base is preferably made of a conductive material (for example, a metal such as stainless steel) in order to apply a voltage by the second power supply unit 351. In this case, it is preferable that the head base and the recording head 34 are insulated so that the voltage applied to the head base does not affect the recording head 34.

  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, in order to collect the paper dust floating in the narrow gap space 35a, it is preferable that the outer peripheral surface of the endless belt has adhesiveness. When the paper powder 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 powder does not adhere is located on the lower side. The frequency of removing the paper dust adhering to can be reduced. The driven roller and the endless belt are made of a conductive material (for example, a metal such as stainless steel), and the second power supply unit 351 applies a voltage to the endless belt through the driven roller. Is preferred. In this case, since the paper dust PD is adsorbed to the endless belt by the Coulomb force, the paper dust PD can be further effectively removed.

  (3) In the present embodiment, the case where the third power supply unit 381 performs static elimination has been described, but the third power supply unit 381 may not be provided. In this case, it is preferable that the voltage is applied to the paper P by the first power supply unit 371 so that the charging voltage of the paper P has the same polarity as the charging voltage of the recording head 34. In this case, it is possible to suppress the paper dust PD from adhering to the recording head 34 with a simple configuration. Furthermore, it is more preferable that the voltage is applied to the paper P by the first power supply unit 371 so that the charging voltage of the paper P is approximately equal to the charging voltage of the recording head 34. In this case, it is possible to more effectively suppress the paper powder PD from adhering to the recording head 34 with a simple configuration.

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

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 Paper feeding part 3 Image forming part 31 Conveying part 312 Adsorption roller 32 Conveying belt 321 Suction hole 33 Negative pressure application part 331 Air circulation chamber 332 Guide member (conveying plate)
334 Groove 335 (335a, 335b) Through hole 336 Negative pressure generating part 34 (34a, 34b, 34c, 34d) Recording head 35 Plate-like member (part of space forming part, second voltage applying part)
351 Second power supply unit (part of second voltage application unit)
35a Narrow space 36 Transport guide 37 First electrode (part of the first voltage application unit)
37a Base 37b Discharge part 37c Concave part 371 First power supply part (part of the first voltage application part)
38 Second electrode (part of third voltage application unit)
38a Base 38b Discharge part 38c Concave part 381 Third power supply part (part of the third voltage application part)
4 Paper transport section 5 Paper discharge section

Claims (7)

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 first voltage applying unit that applies a voltage to the recording medium on the upstream side in the conveyance direction of the recording medium with respect to the recording head;
A second voltage application including a space forming unit disposed between the recording head and the first voltage applying unit, and applying a voltage having a polarity opposite to that of the first voltage applying unit to a lower surface of the space forming unit; With
The first voltage application unit applies a voltage having the same polarity as the charging polarity of the recording head to the recording medium,
The said space formation part is an inkjet recording device which forms a narrow space between the mounting surface of the said recording medium in the said conveyance part.   The inkjet recording apparatus according to claim 1, wherein the first voltage application unit includes a needle electrode, and applies a voltage to the recording medium via the needle electrode.   The voltage applied to the recording medium by the first voltage applying unit is set so that the charging voltage of the recording medium is approximately equal to the charging voltage of the recording head. 2. An ink jet recording apparatus according to 1. The space forming portion includes a plate-like member having a flat surface facing the mounting surface of the recording medium in the transport unit and substantially parallel to the mounting surface of the recording medium,
4. The inkjet recording apparatus according to claim 1, wherein the second voltage application unit applies a voltage having a polarity opposite to that of the first voltage application unit to the plate member. 5.   5. The device according to claim 1, further comprising a third voltage application unit that is disposed between the recording head and the space forming unit and applies a voltage having a polarity opposite to that of the first voltage application unit to the recording medium. The ink jet recording apparatus according to any one of the above.   The inkjet recording apparatus according to claim 5, wherein the third voltage application unit includes a needle electrode, and applies a voltage to the recording medium via the needle electrode.   The voltage applied to the recording medium by the third voltage application unit is set so that the charging voltage of the recording medium that has reached directly below the recording head is equal to the charging voltage of the recording head. The inkjet recording apparatus according to claim 5 or 6.

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