JP6154779B2 - Conveying apparatus and inkjet recording apparatus - Google Patents

Description

  The present invention relates to a transport apparatus equipped in a recording apparatus, and an ink jet recording apparatus including the transport apparatus.

  An ink jet recording apparatus is known as a kind of recording apparatus. Ink jet recording apparatuses are widely used in printers, copiers, multi-function machines, and the like because they are small and inexpensive, and the operation sound is quiet. Inkjet recording apparatuses are roughly classified into a line head system and a serial head system.

  In a line head type ink jet recording apparatus, a transport apparatus having a transport belt is generally used. The conveying device is disposed to face the ink jet head, and conveys the recording medium by adsorbing the recording medium onto the conveying belt. Static electricity or negative pressure is used for adsorbing the recording medium. A conveying device that generates negative pressure includes a suction unit that sucks a recording medium via a conveying belt. Further, the suction unit includes a guide member that supports the recording medium via the conveyance belt.

  However, in the line head type ink jet recording apparatus, a recording medium is conveyed at a high speed, and therefore, much more paper dust is generated than in the serial head type. Paper dust is generated by rubbing between the recording medium and the feeding member disposed in the conveyance path of the recording medium. When the recording medium to which paper dust adheres is transported to the bottom of the ink jet head, the paper dust may adhere to the nozzle holes and the nozzle holes may be clogged. When the nozzle hole is clogged, it is difficult to eject ink droplets, and there is a possibility that white streaks occur in the image along the conveyance direction of the recording medium.

  On the other hand, Patent Document 1 discloses an ink jet recording apparatus including a transport device that electrostatically attracts a recording medium to a transport belt. This ink jet recording apparatus has a configuration in which paper dust attached to a conveyor belt is attached to a dust adsorption roller and removed from the conveyor belt.

JP 2006-273444 A

  The ink jet recording apparatus described in Patent Document 1 applies a potential opposite to that of the transport belt to the paper dust attached to the transport belt, while having the same polarity as that of the transport belt with respect to the dust adsorption roller. And a higher potential than the conveyor belt. As a result, the paper dust moves from the conveyor belt to the dust adsorption roller. However, there is a possibility that the paper dust is charged with the same polarity as the dust suction roller due to the potential of the dust suction roller. When the polarity of the paper dust becomes the same as that of the dust adsorption roller, the paper dust repels against the dust adsorption roller. Therefore, there is a possibility that the paper dust is transported to the bottom of the inkjet head without adhering to the dust adsorption roller.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a transport apparatus and an ink jet recording apparatus that can suppress adhesion of paper dust to nozzle holes.

  A conveying apparatus according to one aspect of the present invention is provided in a recording apparatus so as to face a recording head. The transport apparatus includes a transport belt that transports a recording medium and a suction unit that sucks the recording medium through the transport belt. In addition, the transport device includes a charging unit and a foreign matter adhesion unit that is electrically grounded. The charging unit faces the recording medium via the conveyance belt. Foreign matter on the recording medium adheres to the foreign matter adhesion portion by the charged charging portion.

  An ink jet recording apparatus according to an aspect of the present invention includes a recording head and the transport device, and the recording head includes an ink jet head that ejects ink droplets.

  According to the present invention, even if charged paper dust is attached to the recording medium, the paper dust can be attached to the foreign matter attaching portion by repulsion between the charge of the charging portion and the charge of the paper dust. Therefore, the amount of paper dust conveyed to the bottom of the recording head can be suppressed. As a result, adhesion of paper dust to the nozzle holes is suppressed, and ink droplets can be stably ejected from the nozzle holes. Therefore, white streaks along the recording medium conveyance direction are less likely to occur in the image.

1 is a diagram illustrating a schematic configuration of an ink jet recording apparatus including a transport device according to an embodiment of the present invention. It is a top view which shows the guide member which concerns on embodiment of this invention. It is a partially expanded sectional view which shows the guide member which concerns on embodiment of this invention. It is a top view which shows the conveyance belt which concerns on embodiment of this invention. It is an expanded sectional view showing a part of composition of a conveyance device concerning an embodiment of the present invention. It is a top view which shows the modification of the guide member which concerns on embodiment of this invention. It is an expanded sectional view showing a part of composition of a modification of a conveyance device concerning an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . Moreover, the material, shape, dimension, and the like of each component shown in the following embodiments are merely examples, and are not particularly limited.

  FIG. 1 is a diagram illustrating a schematic configuration of an ink jet recording apparatus 1 including a transport apparatus 310 according to an embodiment of the present invention. An ink jet recording apparatus (an example of a recording apparatus) 1 includes an apparatus housing 100, a paper feeding unit 200 disposed below the inside of the device housing 100, and an ink jet recording system disposed above the paper feeding unit 200. The image forming unit 300 includes a sheet conveying unit 400 disposed on one side of the image forming unit 300, and a sheet discharging unit 500 disposed on the other side of the image forming unit 300.

  The paper feed unit 200 includes a paper feed cassette 201 detachably attached to the apparatus housing 100, a paper feed roller 202, and a guide plate 203. The paper feed roller 202 is disposed above one end side of the paper feed cassette 201. The guide plate 203 is disposed between the paper feed roller 202 and the paper transport unit 400.

  In the paper feed cassette 201, a plurality of recording papers (an example of a recording medium) P are stored in a stacked state. Hereinafter, “recording paper” is simply referred to as “paper”. The paper feed roller (pickup roller) 202 is a feeding member that feeds the paper P along the transport direction of the paper P, and takes out the paper P in the paper feed cassette 201 one by one. The guide plate 203 guides the paper P taken out by the paper feed roller 202 to the paper transport unit 400.

  The sheet conveyance unit 400 includes a substantially C-shaped sheet conveyance path 401, a first conveyance roller pair (primary sheet feeding roller pair) 402 provided on the entrance side of the sheet conveyance path 401, and a sheet conveyance path 401. A second conveyance roller pair (secondary paper feed roller pair) 403 provided and a registration roller pair 404 provided on the exit side of the paper conveyance path 401 are provided. The paper transport path 401 constitutes a part of the transport path of the paper P (an example of a recording medium transport path).

  The first transport roller pair 402 is a feed member that feeds the paper P along the transport direction of the paper P, and feeds the paper P fed from the paper feed unit 200 to the paper transport path 401. The second conveying roller pair 403 is also a feeding member. The second transport roller pair 403 transports the paper P sent out by the first transport roller pair 402 in the paper transport direction.

  The registration roller pair 404 performs skew correction of the paper P that has been transported by the second transport roller pair 403. Then, the registration roller pair 404 temporarily waits for the paper P in order to synchronize the timing of image formation on the paper P and the conveyance of the paper P, and then causes the paper P to move to the image forming unit 300 in accordance with the image formation timing. Send it out.

  The image forming unit 300 includes a transport device 310, four types of inkjet heads (an example of a recording head) 340 a, 340 b, 340 c, and 340 d disposed above the transport device 310, and the sheet P with respect to the transport device 310. A transport guide 350 disposed on the downstream side in the transport direction. Although not shown, each of the four types of inkjet heads 340a, 340b, 340c, and 340d is provided with a plurality of nozzles. Ink droplets are ejected from a plurality of nozzles, and an image such as a character or a figure is formed on the paper P. Note that the image forming unit 300 may include a drying device. The drying device dries the ink droplets ejected from the inkjet heads 340a, 340b, 340c, and 340d toward the paper P.

  The conveyance device 310 includes a belt speed detection roller 311, an adsorption roller 312, a driving roller 313, a tension roller 314, a pair of guide rollers 315, an endless conveyance belt 320, and a suction unit 330. In the present embodiment, the suction roller 312 is an example of a foreign matter adhesion portion, and the suction roller 312 is electrically grounded (grounded).

  The transport device 310 is disposed in the apparatus housing 100 so as to face the four types of ink jet heads 340a, 340b, 340c, and 340d. The conveyance belt 320 is stretched between a belt speed detection roller 311, a driving roller 313, a tension roller 314, and a pair of guide rollers 315. The transport belt 320 is driven in the transport direction of the paper P and transports the paper P.

  For example, polyimide (PI), polyamideimide (PAI), polyvinylidene fluoride (PVDF), or polycarbonate (PC) is used as the material of the conveyance belt 320. Preferably, polyimide or polyamideimide is used because unevenness in thickness of the conveyor belt 320 can be reduced. Further, a layer made of a rubber material such as ethylene propylene diene rubber (EPDM) may be formed on the back surface side (the suction part 330 side) of the conveyor belt 320. The thickness of the conveyance belt 320 is, for example, 100 μm.

  The tension roller 314 applies tension to the conveyance belt 320 so that the conveyance belt 320 does not bend. The conveyance device 310 may include a mechanism that changes the direction of the axis of the tension roller 314 according to the meandering of the conveyance belt 320 when the conveyance belt 320 meanders. By such a mechanism, the meandering of the conveyor belt 320 is corrected.

  The belt speed detection roller 311 is disposed on the upstream side in the transport direction of the paper P with respect to the suction unit 330, and rotates due to friction generated between the belt speed detection roller 311 and the transport belt 320. 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 320 is detected. Therefore, when speed unevenness occurs in the rotation speed of the conveyor belt 320, the rotational speed of the driving roller 313 can be controlled to correct the speed unevenness.

  The drive roller 313 is disposed on the downstream side in the transport direction of the paper P with respect to the suction unit 330. Preferably, the driving roller 313 is arranged so that the flatness of the conveying belt 320 can be maintained together with the belt speed detection roller 311. Further, with such an arrangement, the planarity of the conveyor belt 320 is maintained even when the meandering correction of the conveyor belt 320 is performed.

  The driving roller 313 is rotationally driven by a motor (not shown), and rotates the conveying belt 320 in the counterclockwise direction on the paper surface of FIG. 1 by friction generated between the driving roller 313 and the conveying belt 320. The diameter of the driving roller 313 is 30.0 mm, for example.

  When speed unevenness correction of the conveyor belt 320 (rotational speed correction of the driving roller 313) is performed, it is preferable that the inertia moment of the driving roller 313 is small. That is, the driving roller 313 is preferably light. Therefore, in this embodiment, as the driving roller 313, for example, a hollow tube such as an aluminum pipe or a three arrow tube is preferably used. When the speed unevenness correction of the conveyor belt 320 is not performed, it is preferable that the inertia moment of the driving roller 313 is large in order to stabilize the rotation of the driving roller 313 by the flywheel effect. That is, the driving roller 313 is preferably heavy, and a solid metal material is suitably used as the material of the driving roller 313.

  When the conveyance belt 320 is made of a resin material such as polyimide, the surface layer of the driving roller 313 is made of a rubber material such as ethylene propylene diene rubber (EPDM), urethane rubber, or nitrile rubber. When the image forming unit 300 forms an image on the paper P using water-based ink, it is preferable to use EPDM as the material of the surface layer of the driving roller 313 in order to prevent the rubber material from swelling. The thickness of the surface layer made of a rubber material is, for example, 1.0 mm. Moreover, when the layer which consists of rubber materials, such as EPDM, is formed in the back surface side of the conveyance belt 320, the surface layer of the drive roller 313 may be comprised with the metal. When the surface layer of the driving roller 313 is made of aluminum, the surface of the driving roller 313 may be anodized to prevent wear.

  The pair of guide rollers 315 are disposed below the suction unit 330 and maintain a space below the suction unit 330. With such an arrangement, contact between the conveyor belt 320 and the suction unit 330 below the suction unit 330 can be prevented. Of the pair of guide rollers 315, the guide roller 315 close to the drive roller 313 maintains the amount of winding of the transport belt 320 around the drive roller 313. Of the pair of guide rollers 315, the guide roller 315 close to the tension roller 314 maintains the amount of winding of the conveyor belt 320 around the tension roller 314 so that the meandering correction can be stably performed.

  The four types of inkjet heads 340a, 340b, 340c, and 340d are arranged in parallel from the upstream side to the downstream side in the transport direction of the paper P. Each of the inkjet heads 340a, 340b, 340c, and 340d includes a plurality of nozzles (not shown) arranged in the width direction of the transport belt 320 (direction perpendicular to the transport direction of the paper P). The inkjet heads 340a, 340b, 340c, and 340d are referred to as line types. That is, the ink jet recording apparatus 1 is a line head type ink jet recording apparatus.

  Here, a general line head type ink jet recording apparatus will be described. In general, a line head type ink jet recording apparatus includes a single ink jet head having a length equal to or greater than the width of the recording medium in order to eject ink droplets of one color toward the recording medium, or And a plurality of inkjet heads arranged along a direction (width direction of the recording medium) orthogonal to the conveyance direction of the recording medium. In an ink jet recording apparatus that discharges ink droplets of a plurality of colors, a single ink jet head or a set of a plurality of ink jet heads corresponding to each color is arranged along the conveyance direction of the recording medium. The inkjet head is fixed, and the recording medium is conveyed below the inkjet head. An image is formed on the recording medium by ejecting ink droplets from the inkjet head toward the recording medium to be conveyed.

  Returning to the description of the inkjet recording apparatus 1 according to the present embodiment. Each of the plurality of nozzles of the inkjet head 340a communicates with a pressurizing chamber (not shown) formed in the inkjet head 340a. The pressurizing chamber communicates with an ink liquid chamber (not shown) formed in the inkjet head 340a. The ink liquid chamber is connected to a black (Bk) ink tank (not shown) via an ink supply tube (not shown).

  Each of the plurality of nozzles of the inkjet head 340b communicates with a pressurizing chamber (not shown) formed in the inkjet head 340b. The pressurizing chamber communicates with an ink liquid chamber (not shown) formed in the inkjet head 340b. The ink liquid chamber is connected to a cyan (C) ink tank (not shown) through an ink supply tube (not shown).

  Each of the plurality of nozzles of the inkjet head 340c communicates with a pressurizing chamber (not shown) formed in the inkjet head 340c. The pressurizing chamber communicates with an ink liquid chamber (not shown) formed in the ink jet head 340c. The ink chamber is connected to an ink tank (not shown) of magenta (M) via an ink supply tube (not shown).

  Each of the plurality of nozzles of the inkjet head 340d communicates with a pressurizing chamber (not shown) formed in the inkjet head 340d. The pressurizing chamber communicates with an ink liquid chamber (not shown) formed in the inkjet head 340d. The ink liquid chamber is connected to a yellow (Y) ink tank (not shown) through an ink supply tube (not shown).

  The suction unit 330 is disposed on the back side of the conveyance belt 320 so as to face the four types of inkjet heads 340a, 340b, 340c, and 340d via the conveyance belt 320. The suction unit 330 includes an air circulation chamber (an example of a gas circulation chamber) 331, a guide member 332 that covers the upper surface opening of the air circulation chamber 331, and a suction device 336. The guide member 332 supports the paper P via the transport belt 320.

  The suction roller 312 is a driven roller. The suction roller 312 faces the guide member 332 via the transport belt 320, guides the paper P sent from the registration roller pair 404 onto the transport belt 320, and causes the transport belt 320 to suck the paper P. Further, the suction roller 312 is disposed on the upstream side in the transport direction of the paper P with respect to the inkjet head 340a. The inkjet head 340a is an inkjet head disposed on the most upstream side in the transport direction of the paper P among the four types of inkjet heads 340a, 340b, 340c, and 340d.

  In the present embodiment, a pressing force that presses the suction roller 312 toward the transport belt 320 (guide member 332 side) is applied to the suction roller 312. As a result, even when there is a difference between the conveyance speed of the paper P by the registration roller pair 404 and the rotation speed of the conveyance belt 320, the paper P is bent between the registration roller pair 404 and the suction roller 312. The position where the sheet P is brought into close contact with the conveyance belt 320 can correspond to the position where the suction roller 312 is disposed.

  The suction device 336 is a fan, for example. However, the suction device 336 is not limited to a fan, and may be a vacuum pump, for example. When the suction device 336 is driven, the suction unit 330 sucks the paper P via the transport belt 320.

  The transport guide 350 guides the paper P discharged from the transport belt 320 to the paper discharge unit 500. The paper discharge unit 500 includes a discharge roller pair 501 and a discharge tray 502. The discharge tray 502 is fixed to the apparatus casing 100 so as to protrude outside from the discharge port 101 formed in the apparatus casing 100.

  The sheet P that has passed through the conveyance guide 350 is sent in the direction of the discharge port 101 by the discharge roller pair 501, guided to the discharge tray 502, and discharged to the outside of the apparatus housing 100 through the discharge port 101.

  The air circulation chamber 331 is formed by a bottomed cylindrical box-shaped member whose upper surface is open. The suction device 336 is disposed below the air circulation chamber 331. An exhaust port (not shown) is formed on the bottom wall of the box-shaped member forming the air circulation chamber 331 corresponding to the suction device 336. The suction device 336 is connected to a power source (not shown). When the suction device 336 is driven, a negative pressure is generated in the air circulation chamber 331. Due to this negative pressure, the paper P is sucked through the transport belt 320.

  FIG. 2 is a plan view showing the guide member 332, and shows the positional relationship between the four types of ink jet heads 340 a, 340 b, 340 c, and 340 d and the guide member 332. In FIG. 2, the conveyance belt 320 is not shown for easy understanding.

  As shown in FIG. 2, the black (Bk) inkjet head 340 a includes three inkjet heads 341. The three inkjet heads 341 are arranged in a staggered pattern (staggered) along the width direction of the guide member 332 (the direction orthogonal to the paper transport direction).

  The cyan (C) inkjet head 340 b includes three inkjet heads 342. The three inkjet heads 342 are arranged in a staggered pattern along the width direction of the guide member 332.

  The magenta (M) inkjet head 340 c includes three inkjet heads 343. The three inkjet heads 343 are arranged in a staggered pattern along the width direction of the guide member 332.

  The yellow (Y) inkjet head 340 d includes three inkjet heads 344. The three inkjet heads 344 are arranged in a staggered pattern along the width direction of the guide member 332.

  A plurality of grooves 334 are formed on the surface 333 of the guide member 332 (the surface on the conveying belt 320 side). The groove 334 has an oval shape extending in the paper transport direction. FIG. 3 is a partially enlarged sectional view showing the guide member 332. As shown in FIGS. 2 and 3, a through-hole 335 that penetrates the guide member 332 in the thickness direction is formed corresponding to each of the plurality of grooves 334. The cross section of the through hole 335 is circular.

  Further, as shown in FIG. 2, the guide member 332 is provided with a charging unit 337. The charging unit 337 is disposed on the upstream side in the paper transport direction with respect to the inkjet head 340a. Preferably, the charging unit 337 is disposed in the vicinity of the suction roller 312. The charging unit 337 has a surface exposed from the surface 333 of the guide member 332.

  FIG. 4 is a plan view showing the conveyor belt 320. As shown in FIG. 4, a plurality of suction holes 321 are drilled in the conveyor belt 320. The diameter of the suction holes 321 is 2 mm, for example, and the interval between adjacent suction holes 321 is 8 mm, for example.

  A plurality of rows composed of a plurality of suction holes 321 arranged in the paper transport direction are formed in the width direction of the transport belt 320 (a direction orthogonal to the paper transport direction), and the plurality of rows are formed of suction holes 321. Are arranged in a staggered pattern (staggered pattern). On the other hand, as shown in FIG. 2, the guide member 332 has a plurality of rows formed of a plurality of grooves 334 arranged in the paper transport direction in the width direction of the guide member 332 (a direction orthogonal to the paper transport direction). Has been. Corresponding to the rows of the plurality of grooves 334, rows of the plurality of suction holes 321 of the conveyor belt 320 are arranged.

  Each of the plurality of grooves 334 is formed so as to face at least two suction holes 321. As the transport belt 320 advances, the suction holes 321 facing each of the plurality of grooves 334 are replaced one by one.

  The air circulation chamber 331 (see FIG. 1) communicates with the suction hole 321 (see FIG. 4) of the transport belt 320 through the through hole 335 (see FIG. 2) of the guide member 332 and the groove 334.

  Next, the operation of the inkjet recording apparatus 1 will be described with reference to FIG. The paper feed roller 202 takes out the paper P from the paper feed cassette 201. The taken paper P is guided to the first conveying roller pair 402 by the guide plate 203. When a plurality of sheets P are stored in a stacked state in the sheet feeding cassette 201, the sheet feeding roller 202 takes out the uppermost sheet P from the sheet feeding cassette 201.

  The paper P is sent into the paper transport path 401 by the first transport roller pair 402 and is transported in the paper transport direction by the second transport roller pair 403. Then, the sheet P comes into contact with the registration roller pair 404 and stops, and skew correction is performed. Then, the paper P is sent to the image forming unit 300 in accordance with the image formation timing.

  The paper P is guided onto the conveyance belt 320 by the adsorption roller 312 and is adsorbed by the conveyance belt 320. Preferably, the paper P is guided to the transport belt 320 so that the center of the paper P in the width direction coincides with the center of the transport belt 320 in the width direction. The paper P covers part or all of the plurality of suction holes 321 punched in the transport belt 320. The suction unit 330 sucks air (an example of gas) through the through hole 335 and the groove 334 of the guide member 332 and the suction hole 321 of the conveyance belt 320, and negative pressure is generated in the air circulation chamber 331. ing. As a result, negative pressure acts on the paper P, and the paper P is attracted to the transport belt 320. The paper P is transported in the paper transport direction as the transport belt 320 advances.

  The conveyance belt 320 continuously conveys each part of the paper P to positions facing the four types of inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344). During this time, ink droplets of each color are ejected toward the paper P from each of the four types of inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344). As a result, an image is formed on the paper P.

  The paper P is transported from the transport belt 320 to the transport guide 350. The sheet P that has passed through the conveyance guide 350 is sent in the direction of the discharge port 101 by the discharge roller pair 501, guided to the discharge tray 502, and discharged to the outside of the apparatus housing 100 through the discharge port 101.

  According to the line head type inkjet recording apparatus 1 described above, the positions of the inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344) are fixed, and the inkjet head 340a (341). ) 340b (342), 340c (343), and the paper P is conveyed below 340d (344). Therefore, it is possible to increase the recording speed by increasing the conveyance speed of the paper P. For example, in the inkjet recording apparatus 1, the conveyance speed of the paper P can be set to 900 mm / s, and the printing speed can be set to 150 sheets / min with A4 horizontal size paper.

  On the other hand, a general line head type ink jet recording apparatus has a problem that paper dust adheres to nozzle holes and the nozzle holes are easily clogged. This is because the recording medium is transported at a high speed, so that much more paper dust is generated than in the serial head system. Paper dust is generated by rubbing between the recording medium and the feeding member disposed in the conveyance path of the recording medium. When the nozzle holes are clogged, ink droplets cannot be ejected, and white streaks appear in the image along the recording medium conveyance direction.

  The phenomenon of clogging the nozzle holes is likely to occur when the recording medium and the paper dust attached to the recording medium are charged. In other words, since the inkjet head is generally electrically grounded, when the charged recording medium and paper dust are transported to the bottom of the inkjet head, the charge of the recording medium and the charge of the paper dust are repelled. In addition, the paper powder tends to fly toward the head surface (surface on the conveying belt side) of the inkjet head. For this reason, paper dust may adhere to the nozzle holes. Further, even when an insulating material, for example, is used as the material for the transport belt and the guide member, the nozzle holes are easily clogged. This is because the conveyance belt is charged due to friction generated between the conveyance belt and the guide member during operation of the ink jet recording apparatus. In other words, when the charged paper dust is conveyed to the bottom of the inkjet head, the paper dust flies toward the head surface of the electrically grounded inkjet head due to the repulsion between the charge of the conveyor belt and the charge of the paper dust. It is easy and paper dust may adhere to the nozzle hole.

  Charging of the recording medium occurs when the recording medium rubs against a feeding member disposed in the conveyance path of the recording medium when the recording medium contains little water. Further, when the feeding member is charged, the recording medium may be charged by coming into contact with the feeding member. Similarly, the paper powder is charged when the paper powder contains a small amount of water, and the paper powder rubs against the feeding member disposed in the conveyance path of the recording medium or contacts the charged feeding member. It occurs by doing. That is, the recording medium and paper dust are charged in the paper feeding process and the process of conveying the recording medium to the conveyance belt. Charging of the recording medium and paper powder is likely to occur particularly in a low temperature and low humidity environment.

  The recording medium and paper dust may be positively charged or negatively charged, and are not uniformly charged either. However, when the charged paper powder, or the charged recording medium and the paper powder are transported under the inkjet head, a part of the paper powder is directed toward the head surface of the inkjet head. The paper powder may fly and adhere to the nozzle holes.

[Configuration around suction roller 312]
FIG. 5 is an enlarged cross-sectional view illustrating a part of the configuration of the transfer device 310. Specifically, FIG. 5 shows an enlarged part of the configuration around the suction roller 312. In FIG. 5, the air circulation chamber 331 is not shown. As shown in FIG. 5, the suction roller 312 is disposed so as to contact the conveyance belt 320. The charging unit 337 is opposed to the suction roller 312 via the transport belt 320.

The suction roller 312 includes a conductive material, and the conductive material is electrically grounded. For example, a suction roller 312 made of a metal such as SUS may be used. Further, in order to reduce the collision vibration generated when the paper P collides with the suction roller 312, it is preferable that the moment of inertia of the suction roller 312 is small. Therefore, as the adsorption roller 312 made of metal, for example, a hollow roller such as a Mitsuya tube is preferable, but even if an adsorption roller 312 made of semiconductive EPDM foam or semiconductive urethane rubber is used. Good. As the material having conductivity, a material having a volume resistivity of 1.0 × 10 ⁷ Ω · cm or less is preferable in order to suppress charging of the adsorption roller 312.

  As described above, the charging unit 337 has a surface exposed from the surface 333 of the guide member 332. Therefore, friction is generated between the rotating conveyor belt 320 and the charging unit 337, whereby the charging unit 337 is charged. As the material of the charging unit 337, a material that is easily charged by rubbing against the conveyance belt 320 is preferably used. In the present embodiment, the charging unit 337 is made of an insulating material. Thereby, the charging unit 337 can be charged efficiently. As the insulating material, polyoxymethylene (POM), ABS, fluororesin, insulating urethane rubber, urethane foam and the like can be used.

  According to this embodiment, even if the paper dust adhering to the paper P is charged, the repulsion between the charge of the paper dust and the charge of the charging unit 337 causes the suction roller 312 to be electrically grounded. The paper dust can be moved to the surface, and the paper dust can be attached to the surface. Therefore, it is possible to suppress the amount of paper powder conveyed to the lower side of the inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344). As a result, adhesion of paper dust to the nozzle holes is suppressed, and ink droplets can be stably ejected from the nozzle holes. Therefore, white stripes along the paper conveyance direction are less likely to occur in the image.

  In the present embodiment, the suction roller 312 contacts the paper P. Therefore, even if the paper P is charged on the upstream side in the paper conveyance direction with respect to the suction roller 312, the paper P is discharged by contacting the suction roller 312. As a result, the repulsion between the charge of the paper P and the charge of the paper dust is suppressed, so that the paper dust remaining on the paper P without adhering to the suction roller 312 becomes the inkjet heads 340a (341), 340b (342). Even when transported together with the paper P to the lower side of 340c (343) and 340d (344), the movement (flying) of the paper dust to the head surface due to the repulsive action of electric charges hardly occurs.

  In the first place, the paper dust that does not adhere to the suction roller 312 is either not charged from the beginning or has been neutralized by the suction roller 312. Therefore, even if the paper dust that does not adhere to the suction roller 312 and remains on the paper P is conveyed below the inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344), The movement (flying) of the paper dust to the head surface due to the repulsive action of electric charges hardly occurs.

  As shown in FIG. 5, in the present embodiment, the inkjet recording apparatus 1 includes a paper dust collecting member 360. The paper dust collecting member 360 is in contact with the surface of the suction roller 312 and peels and collects the paper dust from the surface of the suction roller 312. With such a configuration, more paper dust can be collected by the suction roller 312 and conveyed to below the inkjet heads 340a (341), 340b (342), 340c (343), and 340d (344). The amount of paper dust can be reduced. For the paper dust collecting member 360, for example, a cleaning blade can be used.

  In the present embodiment, the ink jet recording apparatus 1 includes a receiving member 361. The receiving member 361 receives the paper powder peeled off from the surface of the suction roller 312. With such a configuration, the inside of the apparatus housing 100 can be prevented from being contaminated with paper dust. The receiving member 361 may be detachably held on the apparatus housing 100. Or you may provide the paper powder conveyance path connected to the receiving part 361, and a collection container. In this case, paper powder can be conveyed to a collection container by arranging, for example, a mixer in the paper powder conveyance path.

  In this embodiment, the suction roller 312 presses the charging unit 337 via the transport belt 320. Therefore, since the charging unit 337 rubs more strongly with the rotating conveyance belt 320, the frictional charging of the charging unit 337 can be increased. Accordingly, the paper powder attached to the paper P is easily moved to the surface of the suction roller 312 due to the repulsive action between the charge of the charging unit 337 and the charge of the paper powder.

  In the present embodiment, the length of the region where the charging unit 337 is disposed is longer than that of the suction roller 312 in the direction orthogonal to the paper transport direction. With such a configuration, paper dust can be attached to the suction roller 312 regardless of the position where the paper dust is attached to the paper P. For example, as shown in FIG. 2, the surface portion of the charging unit 337 exposed from the surface of the guide member 332 may have a rectangular shape that is long in a direction orthogonal to the paper transport direction. In this case, it is preferable that the length of the rectangular surface portion is longer than that of the suction roller 312 in the direction orthogonal to the paper transport direction.

  Note that the number of charging units 337 is not limited to one. FIG. 6A is a plan view showing a modification of the guide member 332. As illustrated in FIG. 6A, a plurality of charging units 337 may be provided on the guide member 332. In the example shown in FIG. 6A, the three charging units 337 are arranged along a direction orthogonal to the paper transport direction.

  Further, as shown in FIG. 6B, the charging unit 337 may be provided so as to correspond to a range where paper dust is particularly easily generated. FIG. 6B is a plan view showing another modification of the guide member 332.

  The amount of paper dust generated increases particularly in the range corresponding to the pickup roller of the paper feed unit. This is because the pickup roller of the paper feeding unit applies a large frictional force to the paper P. Further, when the pickup roller applies a frictional force to the recording medium, the recording media may rub against each other. This also increases the amount of paper dust generated. Therefore, it is desirable to arrange the charging unit 337 in a range corresponding to the pickup roller on the downstream side of the sheet conveyance path. In the ink jet recording apparatus 1 shown in FIG. 1, the paper feed roller 202 of the paper feed unit 200 is a pickup roller. The pickup roller is generally arranged at the center in the direction orthogonal to the paper transport direction in the paper transport path. Therefore, as illustrated in FIG. 6B, the charging unit 337 may be provided at the center of the guide member 332 in a direction orthogonal to the sheet conveyance direction. With such a configuration, paper dust can be effectively attached to the suction roller 312.

  Further, as shown in FIG. 7, the charging unit 337 may be disposed at a position away from the suction roller 312. FIG. 7 is an enlarged cross-sectional view illustrating a part of the configuration of a modified example of the transport device 310. Specifically, FIG. 7 shows an enlarged part of the configuration around the suction roller 312. In FIG. 7, the air circulation chamber 331 is not shown.

  As illustrated in FIG. 7, the charging unit 337 may be disposed upstream of the suction roller 312 in the sheet conveyance direction. Thus, even when the charging unit 337 does not face the suction roller 312, the paper powder flies to the surface of the suction roller 312 that is electrically grounded due to the repulsion between the charge of the paper powder and the charge of the charging unit 337. Paper dust can be adhered to the surface. In this case, the charging unit 337 is preferably disposed in the vicinity of the suction roller 312 so that the paper dust can reach the surface of the suction roller 312.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made to the above embodiments.

  For example, in the above embodiment, the suction roller 312 is a driven roller, but the suction roller 312 may be rotationally driven by a driving device such as a motor.

  In the above embodiment, the charging unit 337 made of only an insulating material is used. However, the charging unit 337 is not limited to this. For example, the charging unit 337 may have an insulating material only in a portion exposed from the surface 333 of the guide member 332.

  Further, in the above embodiment, the charging unit 337 is charged by generating friction between the rotating conveyor belt 320 and the charging unit 337. However, the charging method of the charging unit 337 is limited to this method. is not. For example, the charging unit 337 may be charged by applying a bias voltage to the charging unit 337. In this case, the material of the charging unit 337 can be, for example, a metal material.

  Moreover, in the said embodiment, although the adsorption | suction roller 312 which consists only of material which has electroconductivity was used, the adsorption | suction roller 312 is not limited to this. For example, the suction roller 312 may have a conductive material only on the surface thereof.

  In the above embodiment, the charging unit 337 is provided on the guide member 332, but the charging unit 337 is a member different from the guide member 332 as long as the paper powder can be adsorbed to the adsorption roller 312 (adsorption unit). May be held by.

  Moreover, in the said embodiment, although the adsorption | suction roller 312 had the function of the foreign material adhesion part, the foreign material adhesion part may be provided separately from the adsorption roller 312. FIG. In this case, the foreign matter attaching portion does not have to adsorb the paper P to the transport belt 320, and a roller-like one may not be used as the foreign matter attaching portion.

  Moreover, in the said embodiment, although the cross-sectional shape of the through-hole 335 was circular shape, the cross-sectional shape of the through-hole 335 is not limited to circular shape. The through hole 335 may be rectangular, for example.

  In the above embodiment, the case where the present invention is applied to an ink jet recording apparatus including a line type ink jet head has been described. However, the present invention can also be applied to an ink jet recording apparatus including a serial type ink jet head. .

  In the above-described embodiment, three inkjet heads corresponding to each color are arranged in a staggered pattern along a direction orthogonal to the paper conveyance direction. However, the number of inkjet heads corresponding to each color is particularly limited. It is not something. For example, a single inkjet head may be provided for each color. In addition, the arrangement of the plurality of inkjet heads corresponding to each color is not limited to the staggered arrangement, and for example, the plurality of inkjet heads corresponding to each color are arranged in a row along a direction orthogonal to the paper conveyance direction. May be arranged.

  In the above embodiment, the case where the present invention is applied to an inkjet recording apparatus capable of forming a full-color image has been described. However, the present invention can also be applied to an inkjet recording apparatus that forms a monochrome image.

  In the above embodiment, the case where the present invention is applied to an ink jet recording apparatus has been described. However, the present invention can also be applied to other image forming apparatuses (for example, electrophotographic image forming apparatuses).

  In the above embodiment, the case where the recording medium is a sheet is described. However, the recording medium may be other than the sheet (for example, a resin sheet or a cloth).

  In addition, various modifications can be made to the above embodiment without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 100 Apparatus housing 300 Image forming part 310 Conveyor 312 Adsorption roller 320 Conveyor belt 321 Suction hole 330 Suction part 331 Air circulation chamber 332 Guide member 334 Groove 335 Through-hole 337 Charging part 340a, 341 For black (Bk) Inkjet heads 340b, 342 Inkjet heads 340c, 343 for cyan (C) Inkjet heads 340d, 344 for magenta (M) 360 Inkjet heads 360 for yellow (Y) Paper dust collecting member 361 Receiving member

Claims (11)

A conveying device provided in the recording apparatus facing the recording head,
A transport belt for transporting a recording medium;
A suction section for sucking the recording medium through the transport belt;
A charging unit facing the recording medium via the conveyor belt;
Electrically it is grounded, e Bei and foreign matter adhesion portion the foreign matter is deposited on the recording medium by charged the charging unit,
The foreign matter adhering portion is disposed outside the conveyor belt,
The charging unit includes an insulating material, is disposed inside the transport belt, and is charged by friction with the transport belt . The suction unit includes a guide member that supports the recording medium via the transport belt,
The transport device according to claim 1, wherein the charging unit is provided in the guide member.   The transport device according to claim 1, wherein the suction unit includes an air circulation chamber and a suction device. The foreign matter adhesion part is a roller,
The transport device according to claim 2, wherein the roller is opposed to the guide member via the transport belt, and the recording medium is attracted to the transport belt.   The conveyance device according to claim 1, wherein the charging unit is opposed to the foreign matter adhesion unit via the conveyance belt. The charging unit is located in the conveying direction on the upstream side of the recording medium with respect to the foreign substance attachment, transport device according to any one of claims 1 to 4. The transport apparatus according to claim 1 , wherein the charging unit moves the paper dust, which is the foreign matter attached to the recording medium, to the foreign matter attaching portion when the charging portion is charged .   8. The transport device according to claim 1, wherein a length of an area in which the charging unit is arranged is longer than that of the foreign material adhesion unit in a direction orthogonal to a transport direction of the recording medium. . The conveyance device according to any one of claims 1 to 8, wherein the foreign matter adhesion portion includes a material having a volume resistivity of 1.0 × 10 ⁷ Ω · cm or less. The transport apparatus according to any one of claims 1 to 9,
The recording head, and
The recording head includes an inkjet head that ejects ink droplets.   The ink jet recording apparatus according to claim 10, further comprising a paper dust collecting member in contact with a surface of the foreign matter adhering portion.

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