JP2008037642A - Recording medium conveying mechanism and liquid drop discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium conveying mechanism capable of pressing paper to a conveying surface of a recording medium conveying means even with small air capacity. <P>SOLUTION: A total area between the conveying surface of a paper carrier roller 68 and an opening 76 is smaller than the area of the opening 76. Consequently, compressed air flowing into a pressure chamber 72 hardly escapes from a clearance between the conveying surface and the opening 76. Pressure in the pressure chamber 72 is thereby maintained sufficiently, and sufficient pressure is applied to the paper P on the conveying surface. The paper P can thereby be conveyed in a stable state without damaging the surface of the paper P like the case of allowing a starwheel or the like to abut on the surface of the paper P to press the paper P to the conveying surface. Further, compared with the case of pressing the paper P with large air capacity, the flying state of ink drops discharged from a head unit 32 is not disturbed. The printed face of the paper P does not therefore become dirty. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording medium transport mechanism that transports a recording medium and a droplet discharge device equipped with the recording medium transport mechanism.

  In a droplet discharge apparatus such as an ink jet recording apparatus, in order to increase the speed, the droplet discharge head has a multi-nozzle or a line head corresponding to the paper width. However, when the paper is transported at a high speed, the paper is transported to the nip portion of the transport roll pair immediately after the liquid droplet (ink) is ejected from the liquid droplet ejection head, that is, before the ink on the paper is dried. At this time, the ink on the paper adheres to the transport roll, and the ink attached to the transport roll adheres to the paper.

  Therefore, as a method of transporting paper without contacting the printing surface (ink adhesion surface), for example, a fan as a suction means is provided on the back surface of the belt with a hole (opposite side on which the paper is placed). In some cases, the fan is driven to suck the paper from the back surface of the belt to convey the paper in close contact with the belt (see Patent Document 1).

  However, in patent document 1, since suction means, such as a fan, are used, an apparatus structure becomes complicated and leads to a cost increase. Further, the sheet cannot be sufficiently adhered to the belt only by suction from the back surface of the belt.

  Therefore, it is conceivable to use a star wheel on the printing surface side, but ink on the printing surface may adhere to the star wheel. Further, when the paper is glossy paper, the print surface may be damaged by the tooth tip of the star wheel.

Further, there is a type in which air is blown onto the printing surface and the paper is conveyed while pressed against a belt. However, a stable and sufficient pressing force cannot be obtained by simply blowing air onto the paper on the belt. In order to press the paper against the belt with sufficient force, it is sufficient to increase the amount of air blown, but when a large amount of air is blown toward the belt, the air is ejected from the ink jet recording head. There is a risk of disturbing the flying state of the ink droplets.
JP-A-6-55731

  In view of the above-described facts, an object of the present invention is to provide a recording medium conveyance mechanism that can press a sheet against the conveyance surface of a recording medium conveyance unit even with a small air volume.

  According to the first aspect of the present invention, there is provided a conveyance unit that conveys the recording medium, a pressure chamber that is supplied with gas and blows gas from the opening to the conveyance surface of the conveyance unit, and between the conveyance surface and the opening. And holding means for holding the pressure chamber so that the total area of the gap is smaller than the area of the opening.

  According to the first aspect of the present invention, the pressure chamber is held by the holding means so that the total area of the gap between the transport surface and the opening is smaller than the area of the opening. And the gas which flowed into this pressure chamber blows off from the opening part to the conveyance surface of a conveyance means.

  At this time, the gas flowing into the pressure chamber is unlikely to escape from the gap between the conveyance surface and the opening, so that the pressure in the pressure chamber is sufficiently maintained and a sufficient pressure is applied to the recording medium on the conveyance surface.

  Therefore, since the recording medium is pressed against the conveying surface, the recording medium can be conveyed in a stable state. Further, since it is not necessary to press the surface of the recording medium with a star wheel or the like, the surface of the recording medium is not damaged.

  According to a second aspect of the present invention, the holding means includes a gas inflow pipe connected to the pressure chamber and into which gas flows, a frame in which an insertion portion through which the gas inflow pipe can be inserted is formed, and the gas inflow pipe And fixing means for fixing to the frame.

  According to the second aspect of the present invention, the gas inflow pipe connected to the pressure chamber is inserted through the insertion portion formed in the frame, and the gas inflow pipe is fixed to the frame by the fixing means. By changing the fixing position of the gas inflow pipe, the distance between the opening and the conveying surface can be adjusted.

According to a third aspect of the present invention, the holding means is composed of an inflow pipe that is slidably inserted into the gas inlet of the pressure chamber and into which the gas flows. The weight of the pressure chamber is W, When the pressure is P, the area of the opening is S ₁ , and the area of the inflow pipe is S ₂ , W = P × (S ₁ −S ₂ ).

According to the third aspect of the present invention, the gas is introduced into the pressure chamber by the inflow pipe slidably inserted into the gas inlet of the pressure chamber. At this time, when the weight of the pressure chamber is W, the pressure in the pressure chamber is P, the area of the opening is S ₁ , and the area of the inflow pipe is S ₂ , W = P × (S ₁ −S ₂ ). .

  That is, due to the pressure P in the pressure chamber, the pressure chamber of weight W rises along the inflow pipe and creates a gap between the transport surface and the opening. Further, when the pressure in the pressure chamber increases, this gap increases and the gas escapes to the outside, thereby reducing the pressure in the pressure chamber. In other words, by changing the weight of the pressure chamber, the pressure for pressing the recording medium against the conveyance surface is automatically adjusted.

  The invention described in claim 4 is characterized in that a taper for guiding the gas blown from the gap upward is formed on the outer periphery of the opening.

  According to the fourth aspect of the present invention, a taper is formed on the outer periphery of the opening of the pressure chamber, and the gas blown out from the gap is guided upward by this taper. As a result, it is possible to prevent the gas blown from the gap from moving along the transport surface, so that the flying state of, for example, droplets ejected from the recording head is less likely to be disturbed.

  The invention according to claim 5 is characterized in that the pressure chamber is partitioned by a wall in a direction intersecting with the conveyance direction of the recording medium.

  According to the fifth aspect of the present invention, the pressure chamber is divided into a plurality of portions by partitioning the pressure chamber in a direction intersecting the recording medium conveyance direction by the wall. As a result, even if the width of the recording medium is small and the gap between the pressure chamber and the conveyance surface (recording medium) partially increases due to the thickness of the recording medium, the pressure decreases. There will be no overall decline.

  The invention described in claim 6 is characterized in that a plurality of the pressure chambers are provided in a direction crossing the conveyance direction of the recording medium.

  According to the sixth aspect of the present invention, it is possible to provide a plurality of pressure chambers in a direction crossing the recording medium conveyance direction and selectively pressurize the pressure chambers (inflow of gas). As a result, when printing on a recording medium with a small width, the pressure chamber that is not on the recording medium can be adjusted so as not to send gas, so energy can be reduced, and the flying state of the droplets by unnecessary air Will not disturb.

  The invention described in claim 7 is characterized in that a plurality of the pressure chambers are provided in the conveyance direction of the recording medium.

  According to the seventh aspect of the present invention, by providing a plurality of pressure chambers in the recording medium conveyance direction, gas is not sent to the pressure chambers not positioned on the recording medium in accordance with the timing at which the recording medium is conveyed. Energy can be reduced.

  The invention according to claim 8 is characterized in that the conveying means is a roller.

  The invention described in claim 9 is characterized in that the conveying means is an endless belt wound around a driving roll and a driven roll.

  According to the ninth aspect of the present invention, the conveying means is constituted by a driving roll, a driven roll, and an endless belt wound around these, so that the conveying surface becomes planar, and the opening and the conveying surface The distance of the gap can be made constant. Therefore, the gas blown out from the opening does not vary.

  The invention described in claim 10 comprises a droplet discharge head that discharges droplets to a recording medium, and the recording medium transport mechanism described in any one of claims 1 to 9. It is characterized by having.

  According to the tenth aspect of the present invention, the recording medium is conveyed while being pressed against the conveying surface with a sufficient pressure by a small amount of gas blown from the opening. Therefore, the surface of the recording medium is not damaged as when a star wheel or the like is brought into contact with the surface of the recording medium. Further, as compared with the case where the recording medium is pressed with a large air volume, the flying state of the liquid droplets ejected from the liquid droplet ejection head is not disturbed, so that the liquid droplet ejection surface of the recording medium is not soiled.

  Since the present invention is configured as described above, it is possible to press the paper against the conveyance surface of the recording medium conveyance unit even with a small air volume.

  Next, the paper pressing member 70 as the paper transport mechanism (recording medium transport mechanism) according to the first embodiment of the present invention will be described. First, the ink jet recording apparatus 12 provided with the paper pressing member 70 will be described.

  As shown in FIG. 1, a paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 are picked up one by one by a pickup roll 18. be able to. The taken paper P is transported by a plurality of transport roll pairs 20 constituting a predetermined transport path 22. Hereinafter, the term “transport direction” simply refers to the transport direction of the paper P that is a recording medium.

  Above the paper feed tray 16, a paper transport mechanism 29 including a drive roll 24 and a driven roll 26 and an endless transport belt 28 stretched around these is disposed.

  A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  Then, by rotating the paper P while being held by the transport belt 28, it is possible to perform so-called multi-pass image recording by passing through the ejection region SE a plurality of times. Therefore, the surface of the conveyance belt 28 is a circulation path of the paper P in the present invention.

For example, the transport belt 28 is made of a semiconductive polyimide material (surface resistance value 10 ¹⁰ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹² Ω · cm), thickness 75 μm, width 380 mm, circumference What was shape | molded in length 1000mm can be used. Moreover, as the drive roll 24 and the driven roll 26, as an example, a φ50 mm SUS roll can be used.

  Further, the recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roll formed in a cylindrical shape or a columnar shape, for example, without providing the conveyance belt 28 and rotated. However, when the conveyor belt 28 is used as in the present embodiment, the flat portion 28F is formed, so that the recording head array 30 can be arranged corresponding to the flat portion 28F, which is preferable.

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction intersecting the transport direction), and is yellow (Y) and magenta (M). , Cyan (C), and Black (K), four inkjet recording head units 32 (hereinafter simply referred to as head units 32) corresponding to the four colors are arranged along the transport direction to record full-color images. It is possible. The method of ejecting ink droplets in each head unit 32 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method can be applied.

  The ink jet recording head 33 constituting each head unit 32 is controlled by a head controller (not shown). For example, the head controller determines the ink droplet ejection timing and the ink ejection port (nozzle) to be used according to the image information, and sends a drive signal to the inkjet recording head 33.

  The recording head array 30 may be stationary in a direction crossing the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or failure of the ink jet recording head 33 is not reflected in the recording result.

  Above the head unit 32, reservoir tanks 64 corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) are arranged.

  Four maintenance units 34 corresponding to the respective head units 32 are arranged in the vicinity of the recording head array 30 (in this embodiment, both sides in the transport direction). When performing maintenance on the head unit 32, as shown in FIG. 2, the recording head array 30 moves upward, and the maintenance unit 34 moves into the gap formed between the conveyance belt 28 and enters. . Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed in a state facing the nozzle surface 33N (FIG. 3) that is the ejection surface.

  In the present embodiment, the four maintenance units 34 are divided into two sets of two, and the recording head array 30 is arranged on the upstream side in the transport direction and the downstream side in the transport direction of the recording head array 30 during image recording. I am doing so.

  As shown in detail in FIG. 3, a charging roll 36 connected to a power source is disposed on the upstream side of the recording head array 30 in the transport direction. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P can be charged and electrostatically attracted to the transport belt 28.

As the charging roll 36, for example, a roll having a diameter of 14 mm can be used in which conductive rubber is coated on the surface of silicone rubber and the volume resistance value is adjusted to about 10 ⁶ to 10 ⁷ Ω · cm.

  As the power source, a DC power source is shown in FIG. 3, but an AC power source may be used as long as the paper P can be charged to a predetermined potential.

  A registration roll (not shown) is provided further on the upstream side in the transport direction than the charging roll 36, and the paper P is aligned before reaching between the transport belt 28 and the charging roll 36.

  A separation plate 40 (see FIG. 3) is disposed on the downstream side of the recording head array 30 in the conveyance direction, and the sheet P can be separated from the conveyance belt 28. As the peeling plate 40, for example, an aluminum plate having a thickness of 0.5 mm, a width of 330 mm, and a length of 100 mm can be used.

  The peeled paper P is transported by a plurality of rotatable discharge roller pairs 42 constituting a discharge path 44 on the downstream side in the transport direction of the peeling plate 40, and is discharged to a paper discharge tray 46 provided at the upper part of the housing 14. Discharged.

  Below the peeling plate 40, a cleaning roll 48 is disposed so that the conveyance belt 28 can be sandwiched between the drive roll 24 and the surface of the conveyance belt 28 is cleaned.

  A reversing path 52 including a plurality of reversing roller pairs 50 is provided as a reversing unit between the paper feed tray 16 and the conveying belt 28, and the sheet P on which an image is recorded on one side is reversed and conveyed. By holding the belt 28, image recording on both sides of the paper P can be easily performed.

  Between the conveyance belt 28 and the paper discharge tray 46, an ink tank 54 for storing each of the four color inks is provided. The ink in the ink tank 54 is supplied to each head unit 32 by an ink supply line (not shown). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  By the way, a paper transporting roll 68 is provided on the downstream side in the transporting direction of the paper transporting mechanism 29, and the paper P transported by the paper transporting mechanism 29 is moved downstream (the paper discharge tray 46) by the paper transporting roll 68. To be transported).

  As shown in FIGS. 4 to 6, a plurality of (three in the present embodiment) sheet pressing members 70 are arranged above the sheet conveying roll 68 at predetermined intervals along the longitudinal direction of the sheet conveying roll 68. ing.

  The sheet pressing member 70 has a pressure chamber 72 positioned directly above the sheet conveying roll 68. The pressure chamber 72 has a cavity and can store air. A cylindrical gas inflow pipe 74 is connected to the upper surface 72A of the pressure chamber 72 to allow air to flow into the cavity.

  The upper end of the gas inflow pipe 74 is passed through a through hole 58 formed in a frame 57 provided in the ink jet recording apparatus 12, and a nut 59 is fastened to a tap 74A provided at the upper end. With such a configuration, the position of the pressure chamber 72 in the height direction can be changed by changing the screwing amount of the tap 74A and the nut 59.

  A tube 79 is fitted to the mouth of the gas inflow pipe 74, and compressed air generated by a compression pump (not shown) is sent into the pressure chamber 72 through the tube 79 and the gas inflow pipe 74.

  An opening 76 is formed in the bottom surface 72 </ b> C of the pressure chamber 72, and when compressed air flows into the pressure chamber 72, the pressure in the pressure chamber 72 rises and the paper conveyance roll 68 is opened from the opening 76. Air is blown onto the paper P conveyed on the top.

  A tapered portion 72D is formed at a corner (around the opening 76) of the side wall 72B and the bottom surface 72C in the conveying direction of the pressure chamber 72, and the pressure chamber 72 is squeezed downward. ing. Thereby, when the gas in the pressure chamber 72 is blown out from the opening 76, the air leaked from the gap between the opening 76 and the conveying surface is guided upward by the tapered portion 72D.

  The sheet pressing member 70 is disposed in a state where a predetermined gap is provided between the conveyance surface of the sheet conveyance roll 68 and the opening 76. Note that the size of the gap is determined by the screwing amount of the tap 74A and the nut 59 described above.

  Further, the total area between the conveyance surface and the opening 76 (the area of the hatched portion in FIG. 5) is set smaller than the area of the opening 76.

In this embodiment, when the dimension in the width direction of the opening 76 is 5 mm, the dimension in the longitudinal direction is 40 mm, and the area S is 2 cm ² , the size of the gap between the opening 76 and the conveyance surface is 1.5 mm. The total area between the part 76 and the conveyance surface is set to 1.35 cm ² . That is, the ratio of the total area between the opening 76 and the conveyance surface is set to 67% of the area of the opening 76.

  At this time, if the pressure in the pressure chamber 72 is P, a force of P × S is applied to the conveyance surface of the sheet conveyance roll 68. That is, the paper P transported by the paper transport roll 68 is pressed against the paper transport roll 68 with a force of P × S.

Therefore, when the pressure P in the pressure chamber 72 is set to about 5 kPa, the paper P on the paper transporting roll 68 is transported with a pressing force of about 100 gf by the gas blown from the opening 76 having an area S = 2 cm ^2. Pressed onto the roll 68.

  Next, the operation of the first embodiment of the present invention will be described.

  A sheet pressing member 70 is provided above the sheet conveyance roll 68, and compressed air generated by the compression pump flows into the pressure chamber 72 through the gas inflow pipe 74. Then, compressed air is blown out from the opening 76 of the pressure chamber 72, and the paper P is pressed onto the paper transport roll 68.

  At this time, since the total area between the conveyance surface of the paper conveyance roll 68 and the opening 76 is smaller than the area of the opening 76, the compressed air in the pressure chamber 72 flows between the conveyance surface and the opening 76. Since it is difficult to escape from the gap, the pressure in the pressure chamber 72 is sufficiently maintained, and sufficient pressure is applied to the paper P on the transport surface.

  Therefore, since the paper P is pressed against the transport surface with sufficient pressure, the recording medium can be transported in a stable state. Moreover, since it is not necessary to press the surface of the paper P with a star wheel or the like, the surface of the paper P is not damaged. Further, as compared with the case where the paper P is pressed with a large air volume, the flying state of the ink droplets ejected from the head unit 32 is not disturbed, so that the printing surface of the paper P is not soiled.

  Further, by providing a plurality of pressure chambers 72 in the longitudinal direction of the paper transport roll 68 (the width direction of the paper P), for example, the width size of the paper P is small, and the pressure chamber 72 and the transport surface (paper P) partially. Even if there is a place where the pressure decreases as the distance between them increases by the thickness of the paper P, this pressure drop does not reach the whole.

  In the present embodiment, a paper transporting roll 68 is disposed on the downstream side of the paper transporting mechanism 29 in the transporting direction, and the paper P transported by the transporting belt 28 is pressured from the pressure chamber 72 of the paper pressing member 70. However, instead of the sheet conveying roll 68, the sheet pressing member 70 of this embodiment is disposed on the conveying belt stretched between the driving roller and the driven roller, and the sheet conveying roll 68 is pressed. A configuration may be adopted in which the paper P transported from the transport mechanism 29 is pressed onto the transport belt with the pressure from the pressure chamber 72 of the paper pressing member 70.

  Further, in the present embodiment, the configuration in which a plurality of sheet pressing members 70 are arranged along the longitudinal direction of the sheet conveying roll 68 has been described, but in addition to this configuration, a plurality of sheet pressing members 70 are disposed along the conveying direction. It is good also as a structure to arrange. Thus, if a compression pump that generates compressed air is selected or a valve is provided in the gas inflow pipe 74 and the opening and closing of the valve is controlled, the pressure that is not positioned on the paper P in accordance with the timing at which the paper P is conveyed. Since it can adjust so that gas may not be sent to the chamber 72, energy can be reduced.

  Next, a paper transport mechanism 80 according to the second embodiment of the present invention will be described.

  As shown in FIG. 7, on the downstream side in the transport direction of the drive roll 24 (see FIG. 1), a sheet of paper composed of a drive roll 82 and a driven roll 84 and an endless sheet transport belt 86 stretched around them. A transport mechanism 80 is disposed. In this manner, the conveying roll is configured by the driving roll 82, the driven roll 84, and the paper conveying belt 86 wound around them, so that the conveying surface becomes flat, and an opening 96 and a conveying surface of a sheet pressing member 88 described later are provided. The distance between the gaps can be made constant. Therefore, the amount of air that escapes from the gap does not vary.

  A plurality of sheet pressing members 88 are disposed above the sheet conveying belt 86 at predetermined intervals along the longitudinal direction and the conveying direction of the sheet conveying roll 68 (in this embodiment, three in the longitudinal direction and two in the conveying direction). ) Is arranged.

  As shown in FIGS. 8 and 9A, the sheet pressing member 88 has a pressure chamber 90 positioned immediately above the sheet conveying belt 86. The pressure chamber 90 has a cavity and can store air. A circular opening 92 is formed on the upper surface 90 </ b> A of the pressure chamber 90.

  A cylindrical gas inflow pipe 94 is inserted into the opening 92, and the pressure chamber 90 is slidable with respect to the gas inflow pipe 94. That is, the pressure chamber 90 is not fixed to the gas inflow pipe 94, and normally (when the ink jet recording apparatus 12 is not driven) is on standby with the lower surface 90B of the pressure chamber 90 in contact with the conveyance surface. is doing.

  The gas inflow pipe 94 is connected to a compression pump (not shown), and compressed air generated by the compression pump is sent into the pressure chamber 90 through the gas inflow pipe 94.

  An opening 96 is formed in the lower surface 90B of the pressure chamber 90. When the compressed air sent into the pressure chamber 90 through the gas inflow pipe 94 exceeds a predetermined amount (the pressure in the pressure chamber 90 is predetermined). When the value is equal to or greater than the value, the compressed air in the pressure chamber 90 pushes the ceiling 90C (see FIG. 9B). As a result, the pressure chamber 90 moves upward along the gas inflow pipe 94. That is, the pressure chamber 90 is lifted from the transport surface, and a gap is formed between the lower surface 90B of the pressure chamber 90 and the transport surface.

  Further, when the pressure in the pressure chamber 90 rises due to the compressed air sent from the gas inflow pipe 94, a gap between the lower surface 90B of the pressure chamber 90 and the conveying surface increases, and the gas in the pressure chamber 90 is discharged to the outside. escape. As a result, the pressure in the pressure chamber 90 decreases. In this way, the pressure in the pressure chamber 90 is always maintained at a constant value.

Here, as shown in FIG. 9B, the area of the opening 96 of the pressure chamber 90 is S ₁ , the area of the gas inflow tube 94 is S ₂ , and the pressure in the pressure chamber 90 is P. At this time, the force F ₁ for pressing the sheet P against the transport surface is P × S ₁ , and the force F ₂ applied to the ceiling 90C (the force that lifts the pressure chamber 90) is P × (S ₁ −S ₂ ). .

Therefore, the weight of the pressure chamber 90 is set so that the weight of the pressure chamber 90 is W and W = P × (S ₁ −S ₂ ). Thus, the force F ₂ applied to the ceiling portion 90C becomes larger than the weight W of the pressure chamber 90, the pressure chamber 90 is raised from the conveying surface.

Here, by reducing the area _{S 2} of the gas inlet pipe 94, W = P × _{S 1} becomes a force _{F 1} for pressing the sheet P to the conveying surface, the weight W is equal. That is, by changing the weight of the pressure chamber 90, the force F ₁ for pressing the sheet P to the conveying surface is adjusted automatically.

For example, when the pressing force when pressing the paper P against the paper transport belt 86 is set to about 100 gf, the weight of the pressure chamber 90 is set to 100 g. When the area S ₁ of the opening 76 is 2 cm ² and the pressure P ₀ in the pressure chamber 90 is 5 kPa or more, the pressure chamber 90 is lifted from the sheet P, and a gap is formed between the transport surface and the opening 96. it can. Furthermore, when the pressure in the pressure chamber 90 increases due to the compressed air sent from the gas inflow pipe 94 and the gap between the transfer surface and the opening 96 increases, the gas in the pressure chamber 90 escapes to the outside. The pressure in the pressure chamber 90 is maintained at 5 kPa. Therefore, the paper P on the paper transport belt 86 is always pressed onto the paper transport belt 86 with a force of 100 gf.

  Further, by arranging a plurality of sheet pressing members 88 along the longitudinal direction and the conveying direction of the sheet conveying roll 68, selection of a compression pump that generates compressed air and a valve in the gas inflow pipe 94 are provided. By controlling the opening and closing, it is possible to adjust so as not to send gas to the pressure chamber 90 not positioned on the paper P in accordance with the timing when the paper P is conveyed, so that energy can be reduced.

  In the present embodiment, a paper transport mechanism 80 including a drive roll 82 and a driven roll 84 and an endless paper transport belt 86 stretched around these is disposed on the downstream side of the paper transport mechanism 29 in the transport direction. However, instead of the paper transport mechanism 80, the paper transport roll used in the first embodiment may be arranged on the downstream side in the transport direction of the paper transport mechanism 29.

  In the present embodiment, the sheet pressing member 70 (88) has been described as being disposed on the downstream side of the sheet conveying mechanism 29 in the conveying direction. However, as illustrated in FIG. 10, the sheet pressing member 70 (88) is disposed above the sheet conveying mechanism 29. For example, if the paper P is disposed between the head units 32, the paper P is transported by the paper transport mechanism 29 while the paper P is pressed onto the transport belt 28.

  Further, instead of the charging roll 36 (see FIG. 1) arranged on the upstream side of the recording head array 30 in the conveyance direction, the sheet pressing member 70 (88) is arranged at this position, so that the sheet is fed from the conveyance roll pair 20. The incoming sheet P can be transferred onto the conveyor belt 28.

  Further, in the present embodiment, a plurality of sheet pressing members 70 (88) are provided in the width direction of the sheet P, but a plurality of spaces (pressure chambers 112A) are formed by the walls 110 as shown in FIG. The pressure chambers 112 may be arranged along the width direction of the paper P. At this time, compressed air flows from the compression pump (not shown) into the main flow path 116 in the pressure chamber 112 via the gas inflow pipe 114. Then, compressed air flows into each pressure chamber 112 </ b> A via the branch path 118 branched from the main channel 116, and gas is blown from the opening 120 to the conveyance surface.

1 is a schematic diagram of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a schematic diagram of an ink jet recording apparatus according to a first embodiment of the present invention. 1 is a schematic diagram illustrating a configuration of a conveyance belt and the vicinity thereof in an ink jet recording apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view of a paper transport mechanism according to the first embodiment of the present invention. FIG. 3 is a perspective view of a paper transport mechanism according to the first embodiment of the present invention. FIG. 3 is a side cross-sectional view of the paper transport mechanism according to the first embodiment of the present invention. It is a perspective view of the paper conveyance mechanism of the 2nd Embodiment of this invention. It is a perspective view of the paper conveyance mechanism of the 2nd Embodiment of this invention. FIG. 6 is a side cross-sectional view of a paper transport mechanism according to a second embodiment of the present invention. It is the schematic of the inkjet recording device of another form. It is side surface sectional drawing of the paper conveyance mechanism of another form.

Explanation of symbols

12 Inkjet recording device (droplet ejection device)
57 frame (holding means)
59 Nuts (holding means, fixing means)
68 Paper transport roll (transport means)
70 Paper pressing member (recording medium transport mechanism)
72 pressure chamber 72D taper 74 gas inflow pipe 76 opening 79 tube (holding means, gas inflow pipe)
82 Drive roll (conveying means)
84 Follower roll (conveying means)
86 Paper transport belt (transport means)
88 Paper holding member (recording medium transport mechanism)
90 Pressure chamber 92 Opening (holding means, gas inlet)
94 Gas inflow pipe (inflow pipe)
96 opening

Claims (10)

Conveying means for conveying the recording medium;
A pressure chamber into which gas is introduced and blows out the gas from the opening to the conveying surface of the conveying means;
Holding means for holding the pressure chamber so that the total area of the gap between the transfer surface and the opening is smaller than the area of the opening;
And a recording medium transport mechanism.   The holding means includes a gas inflow pipe connected to the pressure chamber and into which gas flows, a frame formed with an insertion portion through which the gas inflow pipe can be inserted, and a fixing means for fixing the gas inflow pipe to the frame. The recording medium transport mechanism according to claim 1, comprising: The holding means is composed of an inflow pipe that is slidably inserted into the gas inlet of the pressure chamber and flows in the gas. The weight of the pressure chamber is W, the pressure in the pressure chamber is P, and the area of the opening The recording medium transport mechanism according to claim ₁ , wherein S is S ₁ and the area of the inflow pipe is S ₂ , W = P × (S ₁ −S ₂ ).   4. The recording medium conveyance mechanism according to claim 1, wherein a taper that guides the gas blown from the gap upward is formed on an outer periphery of the opening. 5. .   5. The recording medium conveyance mechanism according to claim 1, wherein the pressure chamber is partitioned by a wall in a direction intersecting with a conveyance direction of the recording medium.   The recording medium transport mechanism according to claim 1, wherein a plurality of the pressure chambers are provided in a direction intersecting a transport direction of the recording medium.   The recording medium transport mechanism according to claim 1, wherein a plurality of the pressure chambers are provided in the recording medium transport direction.   The recording medium conveyance mechanism according to claim 1, wherein the conveyance unit is a roller.   The recording medium conveyance mechanism according to claim 1, wherein the conveyance unit is an endless belt wound around a drive roll and a driven roll. A droplet discharge head for discharging droplets onto a recording medium;
The recording medium conveyance mechanism according to any one of claims 1 to 9,
A liquid droplet ejection apparatus, comprising:

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