JP6311583B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  An ink jet recording apparatus is known as a kind of recording apparatus. Inkjet recording apparatuses are widely used in printers, copiers, multifunction machines, and the like. An ink jet recording apparatus records an image on a recording medium such as paper by ejecting ink droplets from nozzles of a recording head.

  Further, as a kind of ink jet recording apparatus, one that adsorbs a recording medium on a conveyance belt having a large number of suction holes is known. This type of ink jet recording apparatus transports a recording medium to a position facing a recording head by a transport belt. Further, in this type of ink jet recording apparatus, a transport plate disposed facing the recording head supports the transport belt. The transport plate is provided with a plurality of through holes, and the plurality of through holes of the transport plate and the plurality of suction holes of the transport belt communicate with each other, whereby the recording medium is sucked toward the transport belt.

  For example, Patent Document 1 describes a configuration in which the number of holes (through holes) of a platen (conveying plate) in a region below an inkjet head (recording head) is adjusted. Specifically, the number of through holes in the transport plate in the region below the recording head is set to be smaller than the number of through holes in the transport plate in the region upstream of the recording head in the paper transport direction. According to such a configuration, in the region upstream of the recording head with respect to the paper transport direction, the suction force for sucking the paper toward the transport belt is increased, and the paper is reliably held by the transport belt.

JP 2007-031007 A

  However, in the configuration described in Patent Document 1, the space upstream of the recording head with respect to the sheet conveyance direction is widened. As a result, when the recording medium passes through an area upstream of the recording head with respect to the paper conveyance direction, the space above the recording medium is wide. In addition, the suction hole of the transport belt is closed at a portion of the transport belt where the recording medium is adsorbed. For these reasons, in the region upstream of the recording head with respect to the paper transport direction, the wind speed of the airflow flowing over the recording medium passing through the region is small. Therefore, foreign matters such as paper dust cannot be peeled off from the recording medium passing through the area upstream of the recording head with respect to the paper transport direction by the air flow. Therefore, with the conveyance of the recording medium, the foreign matter may be carried below the recording head and the foreign matter may adhere to the nozzle of the recording head. When foreign matter adheres to the nozzle, nozzle clogging that makes it impossible to eject ink droplets from the nozzle occurs. As a result, an image defect occurs.

  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 foreign matters to nozzles.

  The ink jet recording apparatus of the present invention records an image on a recording medium by ejecting ink droplets. The ink jet recording apparatus includes a guide member, a transport unit, a recording head, a space forming member, and a suction unit. The guide member has a plurality of through holes and guides the recording medium in a predetermined transport direction. The transport unit transports the recording medium in the transport direction. The recording head ejects the ink droplets toward the recording medium being transported by the transport unit. The space forming member is disposed upstream of the recording head with respect to the transport direction, and forms a foreign substance recovery space between the space forming member and the guide member. The suction part generates a suction force in the plurality of through holes. The plurality of through-holes include a first through-hole and a second through-hole that are respectively located near lower ends of an upstream end and a downstream end of the space forming member in the transport direction. The suction portion generates a suction force through the first through hole and the second through hole in the vicinity of the lower ends of the upstream end and the downstream end of the space forming member.

  According to the present invention, adhesion of foreign matter to the nozzle can be suppressed.

1 is a diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a top view which shows the conveyance belt which concerns on embodiment of this invention. It is a top view which shows the conveyance board which concerns on 1st Embodiment of this invention. (A) It is a top view which shows the groove | channel and through-hole of a conveyance board which concern on embodiment of this invention. (B) It is sectional drawing which shows the groove | channel and through-hole of a conveyance board which concern on embodiment of this invention. It is a figure which shows the structure of the recording part which concerns on embodiment of this invention. It is a figure which shows the structure of the vicinity of the plate-shaped member which concerns on embodiment of this invention. It is a figure which shows the relationship between the wind speed in the air inflow port of the narrow gap space which concerns on embodiment of this invention, and the number of non-ejection nozzles. It is a figure which shows the positional relationship of the plate-shaped member which concerns on 1st Embodiment of this invention, and the through-hole of a conveyance board. It is a figure which shows the comparative example of the positional relationship of a plate-shaped member and the through-hole of a conveyance board. It is a figure which shows a mode when a paper approachs into the narrow space which concerns on embodiment of this invention. It is a figure which shows a mode when a paper leaves | separates from the narrow space which concerns on embodiment of this invention. It is a figure which shows the other positional relationship of the plate-shaped member which concerns on 1st Embodiment of this invention, and the through-hole of a conveyance board. It is a figure which shows the other example of the conveyance board which concerns on 1st Embodiment of this invention. It is a figure which shows the positional relationship of the plate-shaped member which concerns on 2nd Embodiment of this invention, and the through-hole of a conveyance board. It is a figure which shows the other example of the suction part which concerns on embodiment of this invention. FIG. 5 is a diagram illustrating another example of a recording head according to an embodiment of the invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in the figures, 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. The materials, shapes, dimensions, etc. shown in the following embodiments are merely examples, and are not particularly limited.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating a configuration of an ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 1 ejects ink droplets and records an image on paper P (an example of a recording medium).

  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, a recording unit 3 disposed above the sheet feeding unit 2, and one of the recording units 3. A sheet conveying unit 4 disposed on the side (right side in FIG. 1) and a sheet discharging unit 5 disposed on the other side (left side in FIG. 1) of the recording unit 3 are provided.

  The paper feed unit 2 feeds the paper P to the paper transport unit 4. The paper feed unit 2 includes a paper feed cassette 21 detachably attached to the apparatus housing 100, a paper feed roller 22, and a guide plate 23. The paper feed roller 22 is disposed above one end side (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.

  The paper feed cassette 21 can store a plurality of sheets of paper P. The paper feed roller 22 (pickup roller) takes out the paper P one by one from the paper feed cassette 21 and feeds it toward the guide plate 23. 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 transports the paper P to the recording unit 3. 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, and a second transport roller pair provided in the middle of the paper transport path 41. 43 and a registration roller pair 44 provided on the exit side of the sheet conveyance path 41.

  The paper transport path 41 is constituted by a guide plate. The first transport roller pair 42 sends out the paper P fed from the paper feed unit 2 into the paper transport path 41. The second transport roller pair 43 feeds the paper P sent by the first transport roller pair 42 toward the registration roller pair 44 with the paper P sandwiched therebetween.

  The registration roller pair 44 performs skew correction of the paper P sent out by the second transport roller pair 43. In addition, the registration roller pair 44 temporarily stops the paper P and synchronizes the recording timing of the image onto the paper P with the conveyance timing of the paper P to the recording unit 3. The data is sent to the recording unit 3 in accordance with the recording timing. More specifically, the sheet P comes into contact with the registration roller pair 44 and stops. The skew correction of the paper P is performed by this contact. Thereafter, the registration roller pair 44 sends the paper P to the recording unit 3 in accordance with the image recording timing.

  The recording unit 3 records an image on the paper P while conveying the paper P. The recording unit 3 includes a conveyance unit 31, a conveyance plate 32 (an example of a guide member), a conveyance guide 33, four types of recording heads 34a, 34b, 34c, and 34d, and a plate-like member 35 (an example of a space forming member). ), A head base 36, and a suction part 37. Since the four types of 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 sent from the registration roller pair 44. The conveyance unit 31 includes a conveyance belt 310 (an example of an endless belt). The conveyance unit 31 rotates the conveyance belt 310 in a predetermined rotation direction (counterclockwise direction in FIG. 1). The paper P sent out by the registration roller pair 44 is guided onto the transport belt 310. As the conveyance belt 310 rotates, the paper P is conveyed.

  The conveyance plate 32 supports the conveyance belt 310 and supports the paper P via the conveyance belt 310. The conveyance plate 32 guides the paper P conveyed by the conveyance unit 31 (conveyance belt 310) in the direction indicated by the arrow X (sub-scanning direction). Hereinafter, the direction in which the paper P is transported by the transport unit 31 (the transport belt 310) is referred to as a paper transport direction X.

  The conveyance guide 33 is arranged on the downstream side (left side in FIG. 1) of the conveyance plate 32 with respect to the sheet conveyance direction X. Therefore, the conveyance plate 32 guides the paper P to the conveyance guide 33. That is, the transport unit 31 sends the paper P to the transport guide 33. The transport guide 33 guides the paper P sent out by the transport unit 31 to the paper discharge unit 5.

  The recording head 34 is held by the head base 36 and disposed above the conveyance unit 31, and faces the conveyance plate 32 via the conveyance belt 310. The recording head 34 records an image on the paper P while the transport unit 31 (transport belt 310) transports the paper P. Specifically, the recording head 34 ejects ink droplets toward the paper P that passes through a position facing the recording head 34. As a result, images such as characters and figures are recorded on the paper P.

  The plate-like member 35 is arranged on the upstream side (right side in FIG. 1) of the recording head 34 with respect to the paper transport direction X. Specifically, the plate-like member 35 is disposed on the upstream side of the recording head 34a located on the most upstream side in the paper transport direction X among the recording heads 34a, 34b, 34c, and 34d. Accordingly, the paper P passes below the plate-like member 35, then passes below the recording head 34, and reaches the conveyance guide 33. Hereinafter, the recording head 34a may be referred to as the most upstream recording head 34a.

  Further, the plate-like member 35 is fixed to the surface of the head base 36 on the conveying unit 31 side (conveying plate 32 side) and is disposed above the conveying unit 31. That is, the plate-like member 35 faces the conveyance plate 32 with the conveyance belt 310 interposed therebetween. As a result, a narrow space 351 (an example of a foreign matter collection space) is formed between the transport belt 310 and the plate member 35. By fixing the plate member 35 to the head base 36, the plate member 35 can be easily arranged at a predetermined position.

  The suction unit 37 is disposed below the conveyance plate 32. The suction unit 37 sucks the paper P toward the transport belt 310 via the transport plate 32 and the transport belt 310. As a result, the paper P is attracted to the transport belt 310.

  The paper discharge unit 5 discharges the paper P to the outside of the apparatus housing 100. 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 port 11 is formed on one side surface (left side surface in FIG. 1) of the apparatus housing 100.

  The discharge roller pair 51 sends the paper P that has passed through the conveyance guide 33 in the direction of the discharge port 11. The paper P delivered by the discharge roller pair 51 is guided by the discharge tray 52, discharged to the outside of the apparatus housing 100 through the discharge port 11, and placed on the discharge tray 52. When images are continuously recorded on a plurality of sheets P, the plurality of sheets P are stacked on the discharge tray 52.

  In the present embodiment, the plate-like member 35 forms a narrow gap space 351 upstream of the most upstream recording head 34a in the paper transport direction X. Thereby, wind can be generated in the narrow space 351. And the foreign substance like paper dust can be peeled from the paper P with the wind. That is, there is a possibility that foreign matter is attached to the paper P sent from the registration roller pair 44 to the recording unit 3. On the other hand, by providing the plate-like member 35, the foreign matter is peeled off from the paper P before the paper P reaches the position facing the most upstream recording head 34a, and is conveyed below the recording head 34. The amount of foreign matter can be reduced. As a result, the adhesion of foreign matter to the nozzles of the recording head 34 can be suppressed.

  Foreign matter can occur during the papermaking process. Specifically, cutting powder (paper dust) may be generated on the cut surface of the paper P in the cutting process, and may adhere to the paper P. Further, the surfaces of the paper P may rub against each other during packing, and foreign matters such as paper powder, calcium carbonate, and talc may be peeled off from the paper P and adhere to the paper P.

  Further, paper dust may be generated when the paper P is conveyed in the inkjet recording apparatus 1. For example, when the paper P is rubbed against the paper feed roller 22, fibers and fillers may be peeled off from the paper P, and may become paper dust and adhere to the paper P. Similarly, the paper P may be rubbed with a transport roller such as the first transport roller pair 42 to generate paper dust. Further, there is a possibility that the paper P is rubbed against the guide plate constituting the paper transport unit 4 to generate paper dust. Further, when the paper feed roller 22 picks up the paper P, the paper P to be picked up may rub against the paper P stored in the paper feed cassette 21 to generate paper dust.

  Further, there is a possibility that foreign matters such as paper dust adhering to the paper P may adhere to the transport rollers such as the first transport roller pair 42. In this case, the foreign matter adhering to the transport roller may adhere again to the paper P to be transported later, and as a result, the amount of foreign matter transported by the paper P at a time may increase.

  In addition, various air flows are generated inside the apparatus housing 100 of the inkjet recording apparatus 1. For example, air flows from above the conveyor belt 310 into the suction unit 37. Further, as the paper P is transported, an air flow in the paper transport direction X occurs. Accordingly, the sheet P passes under the recording head 34 while being hit by the wind. Further, since the space between the recording head 34 and the conveyance belt 310 is narrow, a relatively strong wind is likely to be generated between the recording head 34 and the conveyance belt 310. Accordingly, the environment below the recording head 34 is an environment in which foreign matter is likely to be blown off from the paper P by the wind. Therefore, there is a possibility that the foreign matter blown off from the paper P adheres to the nozzles of the recording head 34.

  The adhesion of paper dust is generally dominated by the Coulomb force. For this reason, when an electric field is generated between the transport plate 32 and the recording head 34, the paper powder may fly and be attracted to the recording head 34 by the electric force. As a result, paper dust may adhere to the nozzles of the recording head 34.

  In the present embodiment, foreign matter such as paper dust is peeled off the paper P by generating wind in the narrow space 351. The air flowing in the narrow space 351 needs to flow at a sufficient wind speed to separate the foreign matter from the paper P. Specifically, when the paper P enters the narrow space 351, the air inlet of the narrow space 351 (specifically, between the plate-like member 35 and the paper P. The same applies hereinafter) 6. Foreign matter can be peeled from the paper P by generating wind (air flow) at a wind speed of 0.0 m / second or more. The foreign matter separated from the paper P is sucked into the suction unit 37.

  Next, the conveyance belt 310 will be described with reference to FIG. FIG. 2 is a plan view showing the conveyor belt 310. As shown in FIG. 2, a plurality of suction holes 311 are formed in the transport belt 310. The diameter of the suction hole 311 may be 2 mm. Further, the interval between adjacent suction holes 311 may be 8 mm.

  The plurality of suction holes 311 are arranged along the paper transport direction X and the direction (main scanning direction) orthogonal to the paper transport direction X. Hereinafter, a direction orthogonal to the paper transport direction X is referred to as a paper width direction. The plurality of suction holes 311 can be arranged in a staggered manner as shown in FIG.

  Next, the conveyance plate 32 will be described with reference to FIGS. 3 and 4. FIG. 3 is a plan view showing the transport plate 32. Specifically, FIG. 3 shows a part of the surface 320 of the transport plate 32 on the recording head 34 (see FIG. 1) side. Hereinafter, the surface 320 on the recording head 34 side of the transport plate 32 may be referred to as a support surface 320. The transport plate 32 supports the paper P by the support surface 320 via the transport belt 310 (see FIG. 1).

  The conveyance plate 32 is made of a metal material. Specifically, as the material of the conveying plate 32, an aluminum die cast, a pressed plate, or the like can be used. Alternatively, it is possible to select a resin excellent in slidability with the conveyor belt 310 as the material of the conveyor plate 32. When the transport plate 32 is made of a metal material, the transport plate 32 can be grounded.

  As shown in FIG. 3, a plurality of grooves 321 are formed on the support surface 320. Each groove 321 is a long groove opened on the recording head 34 (see FIG. 1) side. Specifically, each groove 321 has an oval shape extending in the paper transport direction X.

  The plurality of grooves 321 are arranged along the paper transport direction X and the paper width direction. The plurality of grooves 321 may be arranged in a staggered manner as shown in FIG. Specifically, the plurality of grooves 321 are arranged at positions that can face the suction holes 311 (see FIG. 2) of the transport belt 310. That is, the plurality of grooves 321 are arranged at a position where they can communicate with the suction hole 311. With this arrangement, the suction holes 311 facing the grooves 321 are replaced one by one as the conveyance belt 310 advances (rotates). Each groove 321 is formed so as to face at least two suction holes 311.

  A plurality of through holes 322 are formed in the transport plate 32. The plurality of through holes 322 are located in the plurality of grooves 321. Specifically, one through hole 322 is located in each groove 321. Each through hole 322 communicates with a corresponding groove 321. The cross section of each through hole 322 may be circular. The plurality of through holes 322 may be arranged in a staggered manner as shown in FIG.

  In FIG. 3, a broken line A indicates a row in which a plurality of through holes 322 are arranged in the paper width direction, and a broken line B indicates a row in which the through holes 322 do not exist in the paper width direction. In the present embodiment, the rows A and B are alternately arranged along the paper transport direction X.

  4A is a plan view showing the groove 321 and the through hole 322, and FIG. 4B is a cross-sectional view showing the groove 321 and the through hole 322. Specifically, FIG. 4A shows the groove 321 and the through-hole 322, and FIG. 4B shows a cross section of the transport plate 32 along the line AA shown in FIG. 4A. As shown in FIGS. 4A and 4B, the through hole 322 passes through the transport plate 32 in the thickness direction, and one end of the through hole 322 opens into the corresponding groove 321. .

  Next, the configuration of the recording unit 3 will be described with reference to FIGS. 1, 2, and 5. FIG. 5 is a diagram illustrating a configuration of the recording unit 3. FIG. 5 shows a cross section of the conveying plate 32 and a cross section of a part of the suction portion 37 (box-like member 371) for easy understanding.

  The transport unit 31 faces the recording head 34 in the apparatus housing 100 (see FIG. 1). The conveyance unit 31 includes a drive roller 312, a belt speed detection roller 313, a tension roller 314, and a pair of guide rollers 315 arranged on the inner peripheral side of the conveyance belt 310. The transport unit 31 further includes a suction roller 316 disposed on the outer peripheral side of the transport belt 310.

  The conveyance belt 310 is stretched around a driving roller 312, a belt speed detection roller 313, a tension roller 314, and a pair of guide rollers 315. A transport plate 32 and a suction unit 37 are disposed on the inner peripheral side of the stretched transport belt 310. The conveyance plate 32 faces the recording head 34 and the plate-like member 35 with the conveyance belt 310 interposed therebetween. The suction unit 37 is disposed below the transport plate 32 on the inner peripheral side of the transport belt 310.

  The drive roller 312 is disposed on the downstream side (left side in FIG. 5) of the transport plate 32 with respect to the paper transport direction X. The driving roller 312 is rotationally driven by a motor (not shown), and rotates the conveyance belt 310 in a predetermined rotation direction (counterclockwise direction in FIG. 5). As the transport belt 310 rotates, the paper P is transported in the paper transport direction X.

  The belt speed detection roller 313 is disposed on the upstream side (the right side in FIG. 5) with respect to the paper conveyance direction X with respect to the conveyance plate 32, and rotates due to the friction generated between the conveyance speed and the conveyance belt 310. Preferably, the belt speed detection roller 313 is arranged so as to maintain the flatness of the conveyance belt 310 at a location facing the recording head 34 together with the driving roller 312.

  The belt speed detection roller 313 includes a pulse plate (not shown), and the pulse plate rotates integrally with the belt speed detection roller 313. By measuring the rotational speed of the pulse plate, the rotational speed of the conveyor belt 310 is detected.

  The tension roller 314 applies tension to the conveyance belt 310 so that the conveyance belt 310 does not bend. The pair of guide rollers 315 guides the conveyor belt 310 so that the conveyor belt 310 passes below the suction unit 37.

  The suction roller 316 is a driven roller. The suction roller 316 faces the upstream end of the transport plate 32 in the paper transport direction X via the transport belt 310. The suction roller 316 guides the paper P sent from the registration roller pair 44 (see FIG. 1) onto the transport belt 310 and causes the transport belt 310 to suck the paper P.

  The suction unit 37 sucks air through the grooves 321 and the through holes 322 of the transport plate 32 and the suction holes 311 (see FIG. 2) of the transport belt 310. By this suction, wind is generated in the space below the head base 36. When the paper P is guided onto the transport belt 310 and covers a part of the transport belt 310, a suction force (negative pressure) acts on the paper P and the paper P is attracted to the transport belt 310. The suction part 37 includes a box-shaped member 371 whose upper surface is open, a suction device 372, and a duct 373.

  The conveyance plate 32 is disposed so as to cover the upper surface opening of the box-shaped member 371. A pressure chamber 374 is defined by the transport plate 32 and the box-shaped member 371. The pressure chamber 374 communicates with the suction hole 311 of the transport belt 310 through the through hole 322 and the groove 321 of the transport plate 32.

  The suction device 372 is fixed to the lower surface of the box-shaped member 371. Specifically, an opening 375 is formed in the bottom wall of the box-shaped member 371, and the suction device 372 is disposed corresponding to the opening 375. A duct 373 is connected to the lower surface of the suction device 372. The suction device 372 is a fan. For example, a blower fan can be used as the suction device 372. However, the suction device 372 is not limited to a fan, and may be a vacuum pump, for example.

  When the suction device 372 is driven, a negative pressure (gauge pressure) of 500 Pa is generated in the pressure chamber 374. Due to this negative pressure, a suction force is generated in the groove 321 through the through hole 322, and a suction force is generated in the suction hole 311 of the transport belt 310 through the groove 321. As a result, air is sucked into the pressure chamber 374 through the suction hole 311 of the transport belt 310, the groove 321 of the transport plate 32, and the through hole 322 of the transport plate 32. The air sucked into the pressure chamber 374 is exhausted through the suction device 372 and the duct 373. Further, when the paper P is guided onto the conveyance belt 310 and blocks some of the plurality of suction holes 311, a suction force (negative pressure) acts on the paper P from the suction holes 311 closed by the paper P. Then, the paper P is adsorbed to the transport belt 310.

  Each of the four types of recording heads 34a, 34b, 34c, and 34d can eject ink droplets of different colors. Specifically, black, cyan, magenta, and yellow ink droplets can be ejected from the recording heads 34a, 34b, 34c, and 34d, respectively.

  Further, the recording head 34 is held by the head base 36 and can be supported at such a height that a predetermined interval (1 mm) is formed between the recording head 34 and the conveying belt 310. The ink jet recording apparatus 1 may include a mechanism for moving the head base 36 up and down according to the thickness of the paper P (recording medium) conveyed by the conveying belt 310. With such a configuration, it is possible to support the recording head 34 at such a height that a predetermined distance (1 mm) is formed between the recording head 34 and the paper P.

  The four types of recording heads 34a, 34b, 34c, and 34d are arranged in parallel from the upstream side to the downstream side in the paper transport direction X (leftward in FIG. 5). The recording head 34 includes a plurality of nozzles (not shown) arranged in the paper width direction (in FIG. 5, the direction orthogonal to the paper surface). Ink droplets are ejected from a plurality of nozzles, and images such as characters and figures are recorded on the paper P.

  The recording head 34 is called a line head. That is, the ink jet recording apparatus 1 is a line head type ink jet recording apparatus. In the present embodiment, the length of the recording head 34 in the paper width direction is equal to or greater than the maximum width of the recording medium that can be guided by the transport plate 32 (that is, the ink jet recording apparatus 1 can record).

  The plate-like member 35 is fixed to the head base 36 and is disposed between the most upstream recording head 34 a and the suction roller 316. The length of the plate-like member 35 in the paper transport direction X is 60 mm. At least the lower surface of the plate-like member 35 can be made of a conductor. Stainless steel or the like can be used as the conductor. The whole plate-like member 35 or the conductor that partially constitutes the plate-like member 35 can be grounded.

  As described above, in the present embodiment, foreign matter such as paper dust is separated from the paper P by generating wind in the narrow space 351. The separated foreign matter is sucked into the pressure chamber 374 and discharged from the duct 373 via the suction device 372.

  A first hole 361 is formed in the head base 36. The first hole 361 is located upstream of the plate-like member 35 with respect to the paper transport direction X (on the right side in FIG. 5). A second hole 362 is formed in the head base 36. The second hole 362 is located downstream (left side in FIG. 5) from the plate-like member 35 with respect to the paper transport direction X. In other words, the first hole 361 and the second hole 362 are provided so as to sandwich the plate-like member 35 in the paper transport direction X.

  Each of the first hole 361 and the second hole 362 is a long hole extending in the paper width direction. When the pressure chamber 374 becomes negative pressure, air flows into the narrow space 351 through the first hole 361 and the second hole 362. In this embodiment, the case where the first hole 361 and the second hole 362 extending in the paper width direction are formed in the head base 36 will be described, but the present invention is not limited to this. The hole formed in the head base 36 may have a shape other than the long hole. For example, a plurality of substantially cylindrical holes may be formed along the paper width direction.

  Next, the distance TD between the plate-like member 35 and the paper P (recording medium) will be described with reference to FIG. FIG. 6 is a diagram showing a configuration in the vicinity of the plate-like member 35.

  In the present embodiment, the distance TD between the plate-like member 35 and the paper P is 1.5 mm or more and 3.0 mm or less. The distance TD is 2 mm, for example. By setting the distance TD in this way and generating a negative pressure (gauge pressure) of 500 Pa in the pressure chamber 374, a wind having a wind speed of 6.0 m / second or more is generated at the air inlet of the narrow space 351. be able to.

  The inventors of the present invention have made extensive studies on the relationship between the wind speed at the air inlet of the narrow space 351 and the number of non-ejection nozzles. Found to decrease. Here, the non-ejection nozzle refers to a nozzle that cannot eject ink droplets due to adhesion of foreign matter. FIG. 7 is a diagram showing the relationship between the wind speed at the air inlet of the narrow space 351 and the number of non-ejection nozzles. In FIG. 7, the horizontal axis represents the wind speed at the air inlet of the narrow space 351 (narrow space inlet wind speed). The vertical axis indicates the number of non-ejection nozzles. As shown in FIG. 7, the number of non-ejection nozzles decreased as the wind speed increased. This trend continued until the wind speed reached 6.0 m / sec. However, when the wind speed exceeded 6.0 m / sec, no change was observed in the number of non-ejection nozzles. Therefore, the present inventors have set 6.0 m / sec or more as the wind speed at the air inlet of the narrow space 351.

  Next, the positional relationship between the plate-like member 35 and the through hole 322 of the transport plate 32 will be described with reference to FIG. FIG. 8 is a diagram illustrating a positional relationship between the plate-like member 35 and the through hole 322 of the transport plate 32. As shown in FIG. 8, the plurality of through holes 322 include a through hole 322a (an example of a first through hole), a through hole 322b (an example of a second through hole), and a through hole 322c (an example of a third through hole). ).

  The through hole 322 a is located near the lower end of the upstream side of the plate-like member 35 in the paper transport direction X. Hereinafter, the upstream end of the plate-like member 35 in the paper transport direction X may be referred to as the upstream end of the plate-like member 35. Further, the through hole 322a may be referred to as an upstream side through hole 322a.

  The through hole 322b is located near the lower end of the downstream side of the plate-like member 35 in the paper transport direction X. Hereinafter, the downstream end of the plate member 35 in the paper transport direction X may be referred to as the downstream end of the plate member 35. The through hole 322b may be referred to as a downstream side through hole 322b.

  The through-hole 322 c is downstream of the upstream end of the plate-like member 35 with respect to the paper transport direction X and upstream of the downstream end of the plate-like member 35. Located below. In other words, the through-hole 322c is located below the inner side of the upstream and downstream ends of the plate-like member 35 in the paper transport direction X. That is, the through hole 322c is located downstream of the upstream side through hole 322a and upstream of the downstream side through hole 322b with respect to the paper transport direction X. Hereinafter, the inner side of each of the upstream and downstream ends of the plate member 35 in the paper transport direction X may be referred to as the inner side of the plate member 35. In addition, the upstream end of the plate member 35 and the downstream end of the plate member 35 may be collectively referred to as both ends of the plate member 35. In addition, the through hole 322c may be referred to as an inner through hole 322c.

  As described above, the through-holes 322 (322a, 322b) are positioned near the lower ends of both ends of the plate-shaped member 35, and the through-holes 322 (322c) are positioned below the inner side of the plate-shaped member 35. The length of the plate-like member 35 in the sheet conveyance direction X and the position of the plate-like member 35 are determined.

  In the present embodiment, a plurality of upstream through holes 322a are arranged along the paper width direction. Similarly, a plurality of downstream through holes 322b are arranged along the paper width direction. That is, the plate-like member 35 is provided so that both ends of the plate-like member 35 are arranged at positions close to the row A described with reference to FIG.

  Furthermore, in the present embodiment, the plurality of upstream through holes 322 a and the plurality of downstream through holes 322 b are all disposed below the plate-like member 35. In addition, a plurality of rows made of a plurality of grooves 321 arranged along the paper transport direction X are formed in the paper width direction, and at least one inner through-hole 322c is formed in each row of the plurality of grooves 321. include.

  According to the present embodiment, the through holes 322 (322a, 322b) are provided in the vicinity of the lower portions of both ends of the plate-like member 35, respectively. Therefore, the suction part 37 (see FIG. 5) can generate a suction force near the lower part of both ends of the plate-like member 35 via the upstream through hole 322a and the downstream through hole 322b, respectively. Furthermore, the suction part 37 can generate a suction force below the inside of the plate-like member 35 through the inner through hole 322c.

  Further, according to the present embodiment, the through hole 322 (322 a) is located near the lower end of the upstream end of the plate-like member 35. As a result, it is possible to reliably generate wind (air flow) flowing into the narrow space 351 (see FIG. 5) from a position upstream of the plate-like member 35 with respect to the paper transport direction X. Hereinafter, the wind that flows into the narrow space 351 from the position upstream of the plate-shaped member 35 with respect to the paper transport direction X may be referred to as the upstream wind that flows into the narrow space 351.

  Further, according to the present embodiment, the through hole 322 (322 b) is located near the lower end of the downstream end of the plate-like member 35. Accordingly, it is possible to reliably generate wind (air flow) that flows into the narrow space 351 from a position downstream of the plate-like member 35 with respect to the paper transport direction X. Hereinafter, the wind that flows into the narrow space 351 from the position downstream of the plate-shaped member 35 with respect to the paper transport direction X may be referred to as the downstream wind that flows into the narrow space 351.

  As described above, according to this embodiment, it is possible to reliably generate the wind from the upstream that flows into the narrow space 351 and the wind from the downstream that flows into the narrow space 351. Accordingly, foreign matters such as paper dust can be efficiently peeled from the paper P in the narrow space 351. Furthermore, in the present embodiment, a plurality of upstream through holes 322a are arranged along the paper width direction. A plurality of downstream through holes 322b are arranged along the paper width direction. According to such a configuration, foreign matters such as paper dust can be more efficiently separated from the paper P in the narrow space 351.

  Moreover, according to this embodiment, the wind from the downstream which flows into the narrow space 351 generate | occur | produces. As a result, it is possible to suppress the flow of air from the position downstream of the plate-like member 35 toward the lower side of the recording head 34. Further, the flow of air from the narrow space 351 toward the lower side of the recording head 34 can be suppressed. Accordingly, it is possible to suppress the amount of foreign matter that peels from the paper P in the narrow space 351 and is carried toward the space below the recording head 34 by the air flow.

  On the other hand, for example, as shown in FIG. 9, when both ends of the plate-like member 35 are arranged at positions close to the row B described with reference to FIG. In either case, the through hole 322 does not exist. Therefore, the amount of wind from the upstream that flows into the narrow space 351 is reduced as compared with the configuration shown in FIG. Similarly, the amount of wind from the downstream flowing into the narrow space 351 is smaller than that in the configuration shown in FIG. As a result, in the configuration shown in FIG. 9, foreign matters such as paper dust cannot be efficiently separated from the paper P as compared to the configuration shown in FIG. 8.

  In the configuration shown in FIG. 9, the amount of wind from the downstream flowing into the narrow space 351 is smaller than that in the configuration shown in FIG. 8. Therefore, compared to the configuration shown in FIG. 8, the amount of foreign matter carried toward the space below the recording head 34 cannot be suppressed.

  Next, the operation of the recording unit 3 will be described with reference to FIGS. 1 to 8, 10, and 11. FIG. 10 is a diagram illustrating a state when the paper P enters the narrow space 351. Specifically, FIG. 10 shows a state in which the foreign matter m is peeled from the front end portion (left end portion in FIG. 10) of the paper P when the paper P enters the narrow space 351. FIG. 11 is a diagram illustrating a state when the paper P is separated from the narrow space 351. Specifically, FIG. 11 shows a state where the foreign matter m is peeled from the rear end portion (the right end portion in FIG. 11) of the paper P when the paper P leaves the narrow space 351.

  When an image is recorded on the paper P, the driving roller 312 is driven to rotate and the suction device 372 is driven. As a result, the conveyor belt 310 rotates and a negative pressure is generated in the pressure chamber 374. Due to this negative pressure, a suction force is generated in each groove 321 through each through hole 322. A suction force is generated in each suction hole 311 of the rotating conveyor belt 310 via each groove 321. Specifically, a suction force is generated in each suction hole 311 (each suction hole 311 on the transport plate 32) located at a location supported by the transport plate 32 in the rotating transport belt 310. As a result, air is sucked into the pressure chamber 374 through the transport plate 32 and the transport belt 310. In addition, air flows into the narrow space 351 from the first hole 361 and the second hole 362.

  The paper P sent to the recording unit 3 by the registration roller pair 44 is guided onto the transport belt 310 by the suction roller 316. At this time, the paper P is preferably guided to the transport belt 310 so that the center of the paper P in the paper width direction coincides with the center of the transport belt 310 in the paper width direction. The paper P covers a part of the transport belt 310. In other words, a part of the plurality of suction holes 311 is covered. As a result, a suction force (negative pressure) acts on the paper P, and the paper P is attracted to the transport belt 310. Then, the paper P is transported in the paper transport direction X as the transport belt 310 rotates.

  The sheet P passes below the plate-like member 35 by the conveyance belt 310 and then passes below the recording head 34. When the paper P enters the lower part of the plate member 35, that is, into the narrow space 351, the front end portion of the paper P is exposed to the wind indicated by the arrow D1, as shown in FIG. The wind indicated by the arrow D1 is a flow of air that flows from the first hole 361 toward the narrow space 351, and blows from the upstream side to the downstream side in the paper transport direction X (to the left in FIG. 10). That is, the wind indicated by the arrow D1 is the wind from the upstream that flows into the narrow space 351 described with reference to FIG. The foreign matter m adhering to the front end portion of the paper P is peeled off from the paper P by this wind. The peeled foreign matter m is guided from the suction hole 311 located below the plate-like member 35 to the groove 321 located below the plate-like member 35 and is introduced into the pressure chamber 374 via the corresponding through-hole 322. It is burned. Then, it passes through the pressure chamber 374, passes through the suction device 372 and the duct 373, and is discharged to the outside.

  Further, when the paper P leaves the narrow space 351, as shown in FIG. 11, the rear end portion of the paper P is exposed to the wind indicated by the arrow D2. The wind indicated by the arrow D2 is a flow of air that flows from the second hole 362 toward the narrow space 351, and blows from the downstream side to the upstream side in the paper transport direction X (to the right in FIG. 11). That is, the wind indicated by the arrow D2 is a wind from the downstream that flows into the narrow space 351 described with reference to FIG. The foreign matter m adhering to the rear end portion of the paper P is peeled off from the paper P by this wind. The peeled foreign matter m is guided from the suction hole 311 located below the plate-like member 35 to the groove 321 located below the plate-like member 35 and is introduced into the pressure chamber 374 via the corresponding through-hole 322. It is burned. Then, it passes through the pressure chamber 374, passes through the suction device 372 and the duct 373, and is discharged to the outside.

  When the paper P passes below the recording head 34, each part of the paper P is continuously conveyed to positions facing the four types of recording heads 34a, 34b, 34c, and 34d. During this time, ink droplets of each color are ejected toward the paper P from the four types of recording heads 34a, 34b, 34c, and 34d. As a result, an image is recorded on the paper P.

  As described above, according to the present embodiment, it is possible to suppress adhesion of foreign matters to the nozzles of the recording head 34. Furthermore, according to this embodiment, the wind from the upstream which flows into the narrow space 351 and the wind from the downstream which flows into the narrow space 351 can be generated reliably. Accordingly, foreign matters such as paper dust can be efficiently peeled from the paper P in the narrow space 351.

  Moreover, according to this embodiment, the wind from the downstream which flows into the narrow space 351 can be generated reliably. Therefore, it is possible to suppress the amount of foreign matter that peels from the paper P in the narrow space 351 and is carried toward the space below the recording head 34 by the air flow.

  Further, according to the present embodiment, at least the lower surface of the plate-like member 35 is made of a conductor. According to such a configuration, it is difficult for the charged paper powder to adhere to the plate-like member 35. In addition, by grounding the conductor constituting the plate-like member 35, the charged paper powder is less likely to adhere to the plate-like member 35.

  Further, according to the present embodiment, since the first hole 361 and the second hole 362 are formed in the head base 36, air can be smoothly flowed into the narrow space 351.

  In the present embodiment, the case where both the upstream through hole 322a and the downstream through hole 322b are arranged below the plate-like member 35 is described, but the present invention is not limited to this. It suffices that the plate-like member 35 is provided so that both ends of the plate-like member 35 are arranged at positions close to the row A described with reference to FIG. Specifically, as shown in FIG. 12, the upstream side through-hole 322 a may be located below the upstream end of the plate-like member 35. Similarly, the downstream side through-hole 322b may be located outside the downstream end of the plate member 35.

  Further, in the present embodiment, the form in which at least one inner through-hole 322c is included in each row including the plurality of grooves 321 has been described, but the present invention is not limited to this. A form in which at least one inner through hole 322c is included in a part of a plurality of rows formed of a plurality of grooves 321 may be employed. For example, as shown in FIG. 13, rows in which the inner through holes 322 c are present and rows in which the inner through holes 322 c are not present may be alternately formed along the paper width direction.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. However, differences from the first embodiment will be described, and descriptions overlapping with the first embodiment will be omitted or simplified.

  FIG. 14 is a diagram illustrating a positional relationship between the plate-like member 35 and the through hole 322 of the transport plate 32 according to the second embodiment. The second embodiment is different from the first embodiment in the configuration of the conveyance plate 32. Specifically, the arrangement of the through holes 322 is different from that of the first embodiment.

  As shown in FIG. 14, in the second embodiment, the through holes 322 are formed in the transport plate 32 so that the number of the downstream through holes 322b is larger than the number of the upstream through holes 322a. That is, the number of through-holes 322 per unit area near the lower end of the downstream side of the plate-like member 35 is larger than the number of through-holes 322 per unit area near the lower end of the upstream side of the plate-like member 35. Many.

  According to such a configuration, the suction force generated below the downstream end of the plate-like member 35 is larger than the suction force generated below the upstream end of the plate-like member 35. As described with reference to FIG. 8, the suction force generated below the downstream end of the plate-like member 35 generates the wind (air flow) from the downstream that flows into the narrow space 351. Therefore, according to the present embodiment, the suction force generated below the downstream end of the plate-like member 35 can be increased, so that the wind speed of the downstream wind flowing into the narrow space 351 can be increased. it can. Then, the wind from the downstream flowing into the narrow space 351 suppresses the amount of foreign matter carried toward the space below the recording head 34 by the air flow. That is, adhesion of foreign matters to the nozzles of the recording head 34 is suppressed. Therefore, according to the present embodiment, the speed of the wind from the downstream flowing into the narrow space 351 can be increased, so that the attachment of foreign matter to the nozzles of the recording head 34 can be further suppressed.

  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, in the embodiment of the present invention, in order to increase the suction force generated below the downstream end of the plate-like member 35, the number of the downstream through holes 322b is made larger than the number of the upstream through holes 322a. However, the present invention is not limited to this. For example, the suction device 372 may be disposed below the downstream end of the plate member 35. Alternatively, for example, as shown in FIG. 15, an independent pressure chamber 374 b may be provided in a region below the downstream end of the plate-like member 35.

  FIG. 15 is a diagram illustrating another example of the suction unit 37. The suction part 37 shown in FIG. 15 includes a partition wall 376 standing in the pressure chamber 374. Specifically, the partition wall 376 surrounds a region below the downstream end of the plate-like member 35. Thereby, the pressure chamber 374 is divided into a first pressure chamber 374a and a second pressure chamber 374b, and a second pressure chamber 374b independent of the first pressure chamber 374a is provided below the downstream end of the plate-like member 35. It is formed. Further, two first openings 375a are formed in the bottom wall of the box-shaped member 371 in the first pressure chamber 374a, and one bottom wall of the box-shaped member 371 in the second pressure chamber 374b has one A second opening 375b is formed. The suction unit 37 includes two first suction devices 372a provided corresponding to the two first openings 375a. Further, the suction unit 37 includes a second suction device 372b provided corresponding to the second opening 375b. That is, according to the configuration shown in FIG. 15, the first pressure chamber 374a in which the suction force by the two first suction devices 372a acts on the space defined by the transport plate 32 (see FIG. 5) and the box-shaped member 371. And a second pressure chamber 374b on which a suction force by the second suction device 372b acts. Therefore, the negative pressure state of the first pressure chamber 374a and the negative pressure state of the second pressure chamber can be individually controlled. Therefore, it is easy to increase the suction force generated below the downstream end of the plate member 35.

  In the embodiment of the present invention, the case where the plate-like member 35 is fixed to the head base 36 has been described. However, the plate-like member 35 is fixed to another fixing member provided in the apparatus housing 100. It may be a form. For example, the form which fixes the both ends of the sheet width direction of the plate-shaped member 35 to a fixing member may be sufficient. According to such a configuration, there is no member that obstructs the flow of air flowing into the narrow space 351 from the downstream side and the upstream side of the plate-like member 35 with respect to the paper transport direction X. The wind speed can be further increased. Therefore, paper dust can be more effectively removed.

  In the embodiment of the present invention, the form in which the transport belt 310 transports the paper P has been described, but the form in which the paper P is transported by other methods may be used. For example, the paper P may be transported by a plurality of transport rollers. In this case, it is preferable to suck air from between adjacent conveyance rollers.

  In the embodiment of the present invention, the form using the transport plate 32 in which the plurality of grooves 321 are formed has been described. However, the form using the transport plate in which the plurality of grooves 321 are not formed may be used. In this case, in order to more reliably attract the paper P to the transport belt 310, it is preferable to use a transport plate having a larger number of through holes 322 than the transport plate 32 in which the plurality of grooves 321 are formed.

  In the embodiment of the present invention, the form in which the narrow space 351 is formed by the plate-like member 35 has been described. However, the form in which the narrow space 351 is formed by other methods may be used. For example, the head base 36 may be formed so as to protrude toward the conveyance belt 310 on the upstream side of the recording head 34 with respect to the sheet conveyance direction X to form the narrow space 351. In this case, the structure can be simplified.

  Alternatively, the narrow space 351 may be formed by a belt stretched around two rollers instead of the plate member 35. Specifically, an endless belt stretched between a driving roller and a driven roller can be used as the space forming member. In this case, it is preferable to arrange the driving roller and the driven roller so that the surface of the endless belt facing the conveyance belt 310 or the conveyance plate 32 is parallel to the conveyance belt 310 or the conveyance plate 32. According to such a configuration, even when paper dust adheres to the endless belt, the endless belt is driven to rotate so that the surface of the endless belt to which paper dust does not adhere is conveyed to the conveyor belt 310 or the conveyor plate. 32. Therefore, it is possible to reduce the frequency with which the serviceman or the like removes the paper dust adhering to the endless belt.

  In the embodiment of the present invention, the case where the first hole 361 is formed in the head base 36 has been described, but the present invention is not limited to this. The length of the head base 36 in the paper transport direction X may be shortened, and the gap between the upstream end of the head base 36 in the paper transport direction X and the suction roller 316 may be increased.

  In the embodiment of the present invention, the case where the transport plate 32 and the box-shaped member 371 are separate members has been described. However, the transport plate 32 and the box-shaped member 371 may be integrally formed. In this case, the negative pressure leak from the pressure chamber 374, that is, the inflow of air into the pressure chamber 374 from the gap between the transport plate 32 and the box-shaped member 371 can be prevented.

  In the embodiment of the present invention, the case where one recording head 34 is provided for each color has been described. However, the present invention is not limited to this. Two or more recording heads 34 may be provided corresponding to each color. For example, as shown in FIG. 16, three recording heads 34 (34a, 34b, 34c, 34d) may be provided for each color. In this case, three recording heads 34 (34a, 34b, 34c, 34d) can be arranged in a staggered pattern along the paper width direction.

  In the embodiments of the present invention, the case where the present invention is applied to an inkjet recording apparatus capable of recording an image in full color has been described. However, the present invention can also be applied to an inkjet recording apparatus that records an image in monochrome. .

  Note that the items described in the embodiment of the present invention can be combined as appropriate.

  The present invention can be used for an electronic apparatus capable of recording an image on a recording medium by ejecting ink droplets.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 3 Recording part 31 Conveying part 310 Conveying belt 32 Conveying plate 321 Groove 322, 322a-322c Through-hole 34, 34a-34d Recording head 35 Plate-shaped member 351 Narrow space 37 Suction part P Paper

Claims (6)

An inkjet recording apparatus that ejects ink droplets and records an image on a recording medium,
A plurality of transmural hole, a guide member for guiding the recording medium in a predetermined conveying direction,
A transport unit that transports the recording medium in the transport direction;
A recording head that ejects the ink droplets toward the recording medium being transported by the transport unit;
A space forming member that is disposed upstream of the recording head with respect to the transport direction and forms a foreign matter recovery space with the guide member;
A suction part for generating a suction force in the plurality of through holes ,
Before SL plurality of through holes includes a first through hole and the second through holes respectively located each in the vicinity of the lower of the upstream end and the downstream end of said space forming member in the conveying direction,
Before Symbol suction unit are each in the vicinity of the lower of the upstream end and the downstream end of the space forming member to generate a suction force through the first through-hole and the second through hole,
The suction force generated near each of the upstream end and the downstream end of the space forming member is the suction force generated near the downstream end below the upstream end. An ink jet recording apparatus that is larger than the suction force generated in the vicinity .   A plurality of the first through holes and a plurality of the second through holes are provided in the vicinity of the lower ends of the upstream end and the downstream end of the space forming member along a direction orthogonal to the transport direction. The ink jet recording apparatus according to claim 1, wherein each of the ink jet recording apparatuses is disposed. The plurality of through-holes further include a third through-hole located below and on the inner side of each of the upstream end and the downstream end of the space forming member,
3. The ink jet recording apparatus according to claim 1, wherein the suction portion generates a suction force below the inner side of the space forming member via the third through hole.   The inkjet recording apparatus according to claim 3, wherein the guide member has a plurality of the third through holes. The ink jet recording apparatus according to claim 1, wherein the first through hole and the second through hole are disposed below the space forming member . The transport unit includes an endless belt that transports the recording medium;
The endless belt has a plurality of suction holes,
The guide member supports the recording medium via the endless belt,
The ink jet recording apparatus according to claim 1, wherein the suction unit generates a suction force in the suction holes communicating with the plurality of through holes through the plurality of through holes. .

Images