JP2006051719A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inkjet recorder which can perform image recording by multipass in a simple and compact structure. <P>SOLUTION: Both of a driving roller 24 and a driven roller 26 have a plurality of roller disks integrally mounted at shafts set along a width direction. The roller disks are arranged with a predetermined interval spaced along the width direction. A recess is constructed at a gap between the roller disks. The roller disks of the driven roller and the roller disks of the driving roller 24 alternately partially enter the recesses. The relation of L<R1+R2 is satisfied for a pitch L between axes of the driving roller 24 and the driven roller 26, a radius R1 of the driving roller 24 and a radius R2 of the driven roller 26. The pitch L between axes can be made small even when the radius R1 of the driving roller 24 and the radius R2 of the driven roller 26 are made large, so that the inkjet recorder 12 can be made compact as a whole. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus compatible with so-called multi-pass that allows a recording medium to pass through an ink droplet ejection region from an ink jet recording head a plurality of times.

  Some ink jet recording apparatuses perform image recording by ejecting ink droplets from an ink jet recording head onto a held recording medium while rotating the recording medium while being held on a drum or the like. By rotating the recording medium in this way, so-called multi-pass is also possible in which the recording medium passes through the ink droplet ejection area from the inkjet recording head a plurality of times.

  For example, Patent Document 1 describes an ink jet printer in which a print medium is held on the outer peripheral surface of a drum and ink is sprayed onto the print medium from each color nozzle unit.

  However, when the print medium is held on a drum having a cylindrical outer peripheral surface as in Patent Document 1, it is necessary to also arrange the nozzle unit obliquely according to this, for example, positioning and maintenance of the nozzle unit, ink, Control and configuration of supply and the like become complicated. Even if the nozzle units are arranged obliquely, it is practically impossible or extremely difficult to make the distance between the nozzle surface and the outer peripheral surface of the drum (print medium) constant. In particular, when the nozzles are two-dimensionally arranged in one nozzle unit, the nozzles exist at different positions in the circumferential direction (rotation direction) of the drum, so the distance between these nozzles and the print medium is set as follows. It is difficult to make it constant. Here, for example, it may be possible to reduce the difference in distance from the print medium for each nozzle by increasing the drum, but the increase in the size of the drum also increases the size of the inkjet printer.

  In Patent Document 2, an electrostatic adsorption belt is supported by two shafts, and a print head can be opposed to a flat portion of the electrostatic adsorption belt so that paper can pass through the print head as many times as possible. A printing press is described.

However, in the configuration of Patent Document 2, since the sheet is curved in the thickness direction at the portion where the electrostatic attraction belt is wound around the shaft, the sheet may be peeled off from the electrostatic attraction belt if the diameter of the shaft is small. If the diameter of the shaft is increased to prevent this, the size of the printing press will be increased.
Japanese Patent Laid-Open No. 10-138516 JP 10-166563 A

  In view of the above-described facts, an object of the present invention is to obtain an ink jet recording apparatus capable of multi-pass image recording with a simple and compact structure.

  According to the first aspect of the present invention, the conveying belt is formed in an endless shape and can circulate while holding the recording medium on the outer peripheral surface, and the circulation driving force is arranged in contact with the conveying belt on the inner side of the conveying belt. A driving roller that acts on the inner side of the conveying belt, and a driven roller that is arranged in contact with the conveying belt at a predetermined inter-axis pitch and is rotated by the circulation of the conveying belt; and the driving roller; An ink jet recording head disposed opposite to a flat portion of the conveying belt formed between the driven roller and ejecting ink droplets according to image information on a recording medium on the flat portion, and the driving roller And at least one of the driven rollers is configured to have a recess that partially overlaps the other roller when viewed in the axial direction.

  Therefore, the recording belt is circulated in a state where the recording medium is held on the outer peripheral surface of the conveying belt, so that the recording medium is passed through the ejection area of the inkjet recording head (area where ink droplets are ejected) multiple times, so-called multipass. Can record images. Since the inkjet recording head is disposed opposite to the flat portion of the conveyance belt formed between the driving roller and the driven roller, for example, it is arranged side by side along the circulation direction of the conveyance belt (the conveyance direction of the recording medium). As in the prior art, it is not necessary to dispose the inkjet recording head obliquely in correspondence with the cylindrical drum. For this reason, a structure becomes simple compared with the structure arrange | positioned diagonally.

At least one of the drive roller and the driven roller is formed with a recess, and the other part of the roller is partially overlapped so that these rollers partially overlap in the axial direction. That is, if the inter-axis pitch between the driving roller and the driven roller is L and these radii are R1 and R2, respectively,
L <R1 + R2
The drive roller and the driven roller can be arranged close to each other so as to satisfy the relationship. As a result, the entire inkjet recording apparatus can be reduced in size.

  Note that at least one drive roller and driven roller need to be provided, but two or more each may be provided. In this case, the flat portion according to the present invention is configured not only between the driving roller and the driven roller but also between the two driving rollers adjacent to each other in the circulation direction of the conveying belt or between the two driven rollers. Including. For example, in the configuration of two driven rollers for one drive roller, a flat portion formed between two driven rollers is also included in the flat portion according to the present invention.

  As a recessed part, the thing formed by cutting the outer peripheral surface of a drive roller or a driven roller to the circumferential direction may be sufficient, for example.

  According to a second aspect of the present invention, in the first aspect of the present invention, at least one of the driving roller and the driven roller is arranged in plural along the axial direction at a predetermined interval, and the conveying belt is provided on an outer peripheral surface. And the recess is configured as a gap between the plurality of roller disks.

  In this way, the driving roller or the driven roller can be configured with a simple configuration in which a plurality of roller disks are arranged at predetermined intervals in the axial direction. In addition, the driving roller or the driven roller is divided in the axial direction by the roller disk, and the concave portion is also configured as a gap between the plurality of roller disks. For example, as described above The structure is simpler than that in which a recess is formed by cutting.

  According to a third aspect of the present invention, in the second aspect of the present invention, both the driving roller and the driven roller include a plurality of the roller disks in which the concave portions are alternately arranged in the axial direction, and the concave portions Further, the drive roller and the driven roller are alternately inserted.

  Thereby, it can comprise so that the roller disk of either a drive roller or a driven roller may have entered into the recessed part partially. That is, the roller disk of the driven roller partially enters the recess of the drive roller, and the roller disk of the drive roller partially enters the recess of the driven roller.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects of the present invention, the conveyor belt is disposed in a region where the driving roller or the driven roller of the recess does not enter. It has the supporting member supported from the inside, It is characterized by the above-mentioned.

  Accordingly, since the support member supports the conveying belt from the inside in the region where the driving roller or the driven roller does not enter, the local depression of the conveying belt is reduced, and the flatness can be more reliably ensured.

  In the invention according to claim 5, in the invention according to any one of claims 1 to 4, the drive roller and the driven roller are symmetrical in the width direction perpendicular to the recording medium conveyance direction. It is characterized by being shaped.

  As a result, the driving roller and the driven roller exert symmetrical tensions on the conveyor belt, so that there is no deviation in the width direction of the conveyor belt and it circulates stably. Since the recording medium held on the conveyance belt is not displaced in the width direction with respect to the ink jet recording head, a high-quality image can be recorded.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the ink jet recording head includes the conveyance belt configured between the driving roller and the driven roller. The plurality of flat portions are provided so as to face each of at least two flat portions.

  Therefore, even when the ink jet recording head is long in the recording medium conveyance direction, the ink jet recording head can be divided and disposed at locations facing the plurality of flat portions. For example, four ink jet recording heads can be divided into two, and can be made to face two flat portions. Further, it is possible to record a high-quality image by arranging more inkjet recording heads as compared with the configuration in which the inkjet recording heads are arranged facing only one flat portion.

  The invention according to claim 7 is characterized in that the ink jet recording head has a width capable of ejecting ink droplets with respect to the entire width of the recording medium in a width direction orthogonal to the conveyance direction of the recording medium.

  Since there is no need to move the ink jet recording head in a direction perpendicular to the recording medium conveyance direction, a mechanism for movement is not required, the ink jet recording apparatus can be miniaturized, and image recording speed is increased. It becomes possible to do. Of course, the inkjet recording head is moved in a direction perpendicular to the moving direction of the recording medium, and the effect of multi-pass image recording (obtaining a high-resolution image with high resolution, or using the inkjet recording head as a result of recording) Etc.) may be obtained. Even in this case, it is not necessary to move the ink jet recording head over the entire width of the recording medium. Therefore, the moving mechanism can be reduced in size, and the ink jet recording apparatus can also be reduced in size.

  Since the present invention has the above-described configuration, multipass image recording can be performed with a simple and compact structure.

  FIG. 1 shows an ink jet recording apparatus 12 according to a first embodiment of the present invention. 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 can be taken out one by one by a pickup roller 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22. Hereinafter, the “conveying direction” simply refers to the conveying direction of the paper P that is a recording medium, and the “upstream” and “downstream” refer to upstream and downstream in the conveying direction, respectively.

  Above the paper feed tray 16, an endless transport belt 28 stretched around a driving roller 24 and a driven roller 26 is disposed, and the transport belt 28 has two flat portions 28F on the top and bottom. . A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F (see FIG. 3) on the upper side 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, the paper P can be passed through the discharge region SE a plurality of times, and so-called multipass image recording can be performed. Therefore, the surface of the conveyance belt 28 is a circulation path of the paper P in the present invention.

  The conveyor belt 28 is made of a polymer material that can cause charges to remain on the surface by charging, for example, polyimide or polyester.

  As shown in FIG. 3, the recording head array 30 has a long shape in which the effective recording area in the present embodiment is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and yellow (Y ), Magenta (M), cyan (S), and black (K), four inkjet recording heads 32 corresponding to each of the four colors are provided. Each of these inkjet recording heads 32 is arranged in the direction in which the longitudinal direction thereof coincides with the width direction of the paper P and the transport direction and along the transport direction, so that a full-color image can be recorded. The method for ejecting ink droplets in each inkjet recording head 32 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method can be applied. The plurality of ink jet recording heads 32 may be integrated to form the recording head array 30.

  Each inkjet recording head 32 is controlled by recording head control means (not shown). For example, the recording head control means 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 32. Further, the overall operation of the inkjet recording apparatus 12 is controlled by system control means (not shown).

  In addition, the recording head array 30 may be fixed in a direction orthogonal to the transport direction, which eliminates the need for a mechanism for moving the recording head array 30 (each inkjet recording head 32). The entire recording apparatus 12 can be reduced in size. If the recording head array 30 is configured to move slightly in the direction orthogonal to the transport direction as necessary, an image with higher resolution can be recorded in the paper width direction by multi-pass image recording. In addition, it is possible to prevent defects (image unevenness, white stripes, etc.) of the ink jet recording head 32 from being reflected in the recording result. Even with this configuration, the moving distance of the recording head array 30 is small, and it is not necessary to move the recording head array 30 over the entire width thereof. For this reason, the mechanism for movement can be simplified and the entire inkjet recording apparatus 12 can be reduced in size. In addition, although a cam etc. can be used as a structure which moves the recording head array 30 (inkjet recording head 32) slightly in the width direction in this way, for example, it is not limited to this.

  As shown in FIGS. 1 and 2, four maintenance units 34 corresponding to the respective ink jet recording heads 32 are arranged in the vicinity of the recording head array 30. Each of the maintenance units 34 wipes, as necessary, a dummy jet receiving member that receives ink droplets jetted from the inkjet recording head 32, a capping member that caps the nozzle surface 32N (see FIG. 3), and the nozzle surface 32N. A wiping member is provided. When maintenance is performed on the inkjet recording head 32, the recording head array 30 moves upward as shown in FIG. 2, and the maintenance unit 34 moves to a gap formed between the conveyance belt 28 and the maintenance unit 34. Get in. Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed while facing the nozzle surface 32N.

  As shown in detail in FIGS. 3 and 4, a suction / charging roller 36 to which a power source (not shown) is connected is disposed upstream of the recording head array 30. The suction / charging roller 36 is driven between the driving roller 24 while sandwiching the conveyance belt 28 and the paper P, and presses the paper P against the conveyance belt 28, and a separation position separated from the conveyance belt 28. It can be moved. At the pressing position, the conveyed paper P can be guided to the transport belt 28. At this time, a predetermined potential difference is generated between the driving roller 24 and the sheet P, so that electric charges can be applied to the conveying belt 28.

As the suction / charging roller 36, for example, a roller having a diameter of 14 mm 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 can be used.

  The power source may be a DC power source or an AC power source as long as the paper P can be charged to a predetermined potential.

  A registration roller (not shown) is provided further upstream than the suction / charging roller 36 and is positioned before the paper P reaches between the conveyance belt 28 and the suction / charging roller 36.

  On the downstream side of the recording head array 30, a plurality of peeling claws 56 that are rotatably held by a shaft member 58 are arranged at a certain interval in the width direction of the paper P. The peeling claw 56 is configured to rotate between a peeling position where the tip of the peeling claw 56 comes into contact with the conveyance belt 28 and separates the paper P from the conveyance belt 28 and a separation position separated from the conveyance belt 28. At the separated position, the paper P is not peeled off from the conveyor belt 28, so that multi-pass image recording is possible.

  Further, a static eliminator 60 is disposed between the recording head array 30 and the peeling claw 56 to assist in the removal of the transport belt 28 and the paper P so that the peeling by the peeling claw 56 can be easily performed.

  The peeled paper P is transported by a plurality of discharge roller pairs 42 that constitute a discharge path 44 on the downstream side of the peeling plate 40, and is discharged to a paper discharge tray 46 provided on the top of the housing 14.

  A reversing path 52 composed of a plurality of reversing roller pairs 50 is provided 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 held on the conveying belt 28. By doing so, it is possible to easily record images on both sides of the paper P.

  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 the recording head array 30 through an ink supply pipe (not shown). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  As shown in FIGS. 5 and 6, each of the driving roller 24 and the driven roller 26 has a shaft 62 disposed along the width direction, and a plurality of roller disks 64 are provided on the shaft 62. It is attached integrally. On the outer peripheral surface of the roller disk 64, the conveyor belt 28 is brought into contact with the inner side to apply a tension, whereby the conveyor belt 28 is stably stretched and supported.

Each of the roller disks 64 is disposed at a constant interval along the width direction (longitudinal direction of the shaft 62), and substantially the outer circumferences of the driving roller 24 and the driven roller 26 that stretch and support the conveying belt 28. The surface is divided in the width direction. A recess 66 according to the present invention is formed in the gap between the roller disks 64. The width of the recess 66 is longer than the thickness of the roller disk 64. Then, the drive disk 24 is driven so that the roller disk 64 of the driven roller 26 partially enters the recess 66 of the drive roller 24 and, similarly, the roller disk 64 of the drive roller 24 partially enters the recess 66 of the drive roller 24. A roller 24 and a driven roller 26 are disposed. Therefore, as shown in FIG. 4, the driving roller 24 and the driven roller 26 alternately enter the recess 66 and partially overlap each other when viewed in the axial direction of these rollers. That is, if the inter-axis pitch between the driving roller 24 and the driven roller 26 is L, the radius of the driving roller 24 is R1, and the radius of the driven roller 26 is R2,
L <R1 + R2
The relationship is satisfied.

  In general, in an ink jet recording apparatus capable of so-called multi-pass, it is necessary to rotate the paper P a plurality of times in a state where the paper P is adsorbed to the transport belt or the like, so that the paper P is prevented from being carelessly peeled off from the transport belt 28. From this viewpoint, it is preferable that the roller on which the conveyor belt is stretched has a large diameter. However, if a large-diameter roller is used, the overall size of the ink jet recording apparatus is increased.

  On the other hand, in the present embodiment, with the above-described configuration, the driving roller 24 and the driven roller 26 that stretch and support the conveying belt 28 are overlapped when viewed in the axial direction. Even if the radius R2 of R1 and the driven roller 26 is increased, the inter-axis pitch L can be reduced. As a result, the entire inkjet recording apparatus 12 can be reduced in size.

  The inter-axis pitch L, the radius R1 of the driving roller 24, and the radius R2 of the driven roller 26 are not particularly limited as long as these conditions are satisfied. For example, in this embodiment, L = 100 mm, R1 = 80 mm, and R2 = 80 mm. Yes.

  Furthermore, in this embodiment, as can be seen from FIG. 6, both the driving roller 24 and the driven roller 26 are configured to be symmetric with respect to the center line CL as an axis of symmetry when viewed in the width direction. As a result, the tension acting on the conveyor belt 28 is also symmetrical, so that it is possible to prevent a deviation (so-called walk) in the width direction of the conveyor belt 28 with respect to the driving roller 24 and the driven roller 26.

  In the ink jet recording apparatus 12 of the present embodiment configured as described above, the paper P taken out from the paper feed tray 16 is transported to the transport belt 28 as described above. Then, the suction and charging roller 36 guides and presses against the conveyance belt 28, and the suction and charging roller 36 attracts and holds the conveyance belt 28 by an applied voltage. In this state, the paper P passes through the ejection area SE by circulation of the conveyance belt 28, and ink droplets are ejected from the recording head array 30, and an image is recorded on the paper P. When recording an image in only one pass, the sheet P and the conveyance belt 28 are neutralized by the static eliminator 60, and then the sheet P is separated from the conveyance belt 28 by the separation claw 56, and is conveyed by the discharge roller pair 42 and discharged. The paper is discharged to the paper tray 46.

  On the other hand, when image recording is performed by multi-pass, the neutralization by the static eliminator 60 is not performed, and the separation claw 56 is also set at the separation position so that the sheet P is circulated until the required number of times is reached and passed through the ejection region SE. . After this reaches a predetermined number of times, the sheet P and the conveyor belt 28 are neutralized by the static eliminator 60, and then the sheet P is separated from the conveyor belt 28 by the peeling claw 56, and is conveyed by the discharge roller pair 42 and discharged. To discharge. Note that the actual number of passes in the case of multi-pass is not particularly limited, and can be determined according to, for example, a desired resolution of a recorded image.

  In the inkjet recording apparatus 12 according to the present embodiment, the transport belt 28 is stretched and supported by the driving roller 24 and the driven roller 26, whereby the flat portion 28F is formed on the transport belt 28, and the flat portion 28F is opposed to the flat portion 28F. In addition, the inkjet recording heads 32 are arranged side by side in the transport direction of the paper P. In a configuration using a cylindrical or columnar conveying member as in the prior art, the inkjet recording head needs to be disposed obliquely. In the present embodiment, the inkjet recording head 32 is disposed side by side along the flat portion 28F. Since it can, it becomes a simple structure.

  Further, in the ink jet recording apparatus 12, as described above, the driving roller 24 and the driven roller 26 are arranged so as to partially overlap each other when viewed in the axial direction, so that the inter-axis pitch L can be reduced. The ink jet recording apparatus 12 is also downsized. In particular, in a configuration for performing multi-pass image recording, it is preferable to use the driving roller 24 and the driven roller 26 having a large diameter in order to rotate the paper P a plurality of times while being sucked and held by the transport belt 28. In the present embodiment, it is possible to use a large diameter roller as the driving roller 24 and the driven roller 26 without causing an increase in the size of the entire inkjet recording apparatus 12. It is also possible to more surely prevent peeling and peeling.

  Further, since the entire length of the transport belt 28 is also shortened, the time for rotating the paper P is shortened, and the time required for image recording (particularly, the time for recording an image on the first paper P (FPOT)) is reduced. Can be shortened.

  Furthermore, in this embodiment, both the driving roller 24 and the driven roller 26 are configured to be bilaterally symmetric when viewed in the width direction, and the shift in the width direction of the conveying belt 28 with respect to the driving roller 24 and the driven roller 26 is prevented. is doing. Therefore, displacement of the paper P with respect to the ink jet recording head 32 is prevented, and a higher quality image can be recorded.

  As in the modification shown in FIG. 7, an auxiliary roller 68 that contacts the conveyor belt 28 from the inside may be provided as necessary. Examples of the auxiliary roller 68 include a tension roller that adjusts the tension by pressing the conveyance belt 28 from the inside. Further, since it is sufficient for the auxiliary roller 68 to perform the above-described operation, if the roller having a smaller diameter than the driving roller 24 and the driven roller 26 is used, the auxiliary roller 68 can be used for the ink jet recording apparatus 12. There will be no increase in size. Even if the small-diameter auxiliary roller 68 is used, if the wrap angle θ at the contact portion of the transport belt 28 (the central angle with the contact portion of the transport belt 28 being an arc) is sufficiently small, the sheet from the transport belt 28 P can be prevented from lifting and peeling.

  FIG. 8 shows the vicinity of the drive roller 24 and the driven roller 26 of the ink jet recording apparatus according to the second embodiment of the present invention. In the second embodiment, the overall configuration of the ink jet recording apparatus is the same as that of the first embodiment, and a description thereof will be omitted.

  In the second embodiment, the driving roller 24 and the driven roller 26 having substantially the same configuration as that of the first embodiment are provided. In addition to these, a supporting member 70 is provided one above the other inside the conveyor belt 28. Different points are provided.

  As shown in FIG. 9, each support member 70 includes a central portion 70A disposed along the width direction of the conveying belt 28 at an intermediate portion between the driving roller 24 and the driven roller 26, and an upstream side from the central portion 70A. And a plurality of branch portions 70B each extending downstream. The branch portion 70 </ b> B enters the recess 66 of the driving roller 24 and the driven roller 26, and the tip portion thereof is curved in accordance with the roller disk 64 of the driving roller 24 and the driven roller 26.

  Therefore, in the second embodiment, the same effect as in the first embodiment is obtained. In the second embodiment, the conveyor belt 28 is supported from the inside by the branch portion 70B of the support member 70 in the recess 66, and the The dent is prevented, and a shape substantially the same as the portion stretched around the driving roller 24 and the driven roller 26 is maintained. Thus, the deformation of the transport belt 28 due to the recess 66 is suppressed, so that the paper P can be transported more stably.

  Further, between the driving roller 24 and the driven roller 26, the conveying belt 28 is supported not only by the branch portion 70B but also by the central portion 70A, and the flatness of the flat portion 28F is maintained high. For this reason, the fluctuation | variation of the space | interval of the inkjet recording head 32 and the paper P at the time of image recording is suppressed, and a higher quality image can be recorded.

  As the support member 70, for example, a metal material (such as stainless steel) that can be molded by a press or a resin material such as plastic can be used.

  Further, the central portion 70A and the branch portion 70B do not necessarily have to be integrated, and may be separated from each other, but it is preferable to integrate them as described above because the number of parts is reduced.

  FIG. 10 shows the vicinity of the drive roller 24 and the driven roller 26 of the ink jet recording apparatus according to the third embodiment of the present invention.

  In the third embodiment, the driving roller 24 and the driven roller 26 are arranged so as to be up and down (in FIG. 10, the driving roller 24 is down and the driven roller 26 is up, but the reverse is also possible), and between them A recording head array 31 composed of two ink jet recording heads 32 is disposed opposite to each of two flat portions 28F of the transport belt 28 that is configured. In one inkjet recording head 32, the length L1 along the transport direction is long, and a predetermined number (for example, four as in the first embodiment) of inkjet recording heads 32 may be arranged side by side on one flat portion 28F. Even when it is difficult or impossible, a predetermined number of ink jet recording heads 32 can be disposed by dividing the ink jet recording heads 32 into two flat portions 28F.

  Further, even when a predetermined number of ink jet recording heads 32 can be disposed opposite to one flat portion 28F, ink jet recording can be performed by further disposing the ink jet recording head 32 opposite to another flat portion 28F. It is also possible to increase the number of heads 32 so that a higher quality image can be recorded.

  In FIG. 10, the driving roller 24 and the driven roller 26 are arranged one above the other so that the flat portion 28F is in the vertical direction. Of course, as in the first embodiment (see FIG. 4), in a configuration in which two horizontal flat portions 28F are positioned vertically, the inkjet recording head 32 faces the upper and lower flat portions 28F. May be arranged. However, in this configuration, the ejection direction of the ink droplets from the upper inkjet recording head 32 and the direction of gravity coincide with each other, but these are reversed in the lower inkjet recording head 32. It is necessary to adjust the discharge state so that the upper and lower ink jet recording heads 32 coincide with each other.

  On the other hand, as shown in FIG. 10, when the two flat portions 28 </ b> F are both configured to be in the vertical direction, the direction of ink droplet ejection and the direction of gravity in both of the two inkjet recording heads 32. Is the same (orthogonal), and the adjustment as described above is simplified and preferable.

  FIG. 11 shows a driving roller 72 and driven rollers 74 and 76 of the ink jet recording apparatus according to the fourth embodiment of the present invention. As shown in FIGS. 12 and 13, in the fourth embodiment, only one drive roller is provided. However, two drive rollers are arranged, and the conveyor belt 28 is stretched between three rollers as a whole. It is supported on the rack.

  As described above, in the present invention, the number of driving rollers and driven rollers is not particularly limited. If the number is one or more (two or more in total), the flat portion 28F of the conveyor belt 28 is interposed between these rollers. Can be configured at least in two places, and the ink jet recording head 32 can be arranged to face the flat portion 28F.

And even in the configuration in which three or more rollers are provided in total, for any two rollers,
(Roller shaft pitch) <(Sum of two roller radii)
Therefore, the overall size of the inkjet recording apparatus can be reduced.

  Further, as shown in FIG. 13, in the fourth embodiment, the positions and thicknesses of the respective roller disks 64 are set so that all the three rollers are symmetrical with respect to the center line CL and do not interfere with each other. Yes. In this way, by making all the three rollers symmetrical, it is possible to prevent the width of the transport belt 28 from shifting with respect to the driving roller and the driven roller.

  In FIG. 11, a plurality of ink jet recording heads 32 are arranged so as to face only one flat portion 28F among the three flat portions 28F formed on the conveyor belt 28. In FIG. As shown, the recording head array 30 (inkjet recording head 32) may be arranged in a plurality of flat portions 28F.

  In the above description, the drive roller and the driven roller are both composed of a plurality of roller disks 64. For example, as shown in FIG. 15, the drive roller 24 'is composed of two roller disks 64'. The driven roller 26 ′ may be configured by one roller disk 64 ″. That is, since the recess 66 ′ is formed between the two roller disks 64 ′ of the drive roller 24 ′, the recess 66 If a part of the roller disk 64 ″ of the drive roller 24 ′ is inserted into “,” the drive roller 24 ′ and the driven roller 26 ′ can overlap each other when viewed in the axial direction. In any configuration, the concave portion of the present invention can be configured as a gap between a plurality of roller disks, so that the structure is not complicated.

  Also in the configuration shown in FIG. 15, as in the second embodiment (see FIG. 9), a support member that supports the conveyor belt 28 from the inside is provided, and the deformation of the conveyor belt 28 due to the recess 66 ′ is deformed. You may make it suppress.

  The drive roller may be at any position in the conveyance direction (or the rotation direction) of the paper P. That is, in order to circulate the conveyor belt 28 among the plurality of rollers, at least one of the rollers is required to be a driving roller. This driving roller is upstream in the conveying direction as in the above embodiments. Or may be on the downstream side in the transport direction.

  Moreover, you may arrange | position other members, such as a sensor which detects the paper P, between these rollers as needed.

It is the schematic which shows the inkjet recording device of 1st Embodiment of this invention in an image recording state. It is the schematic which shows the inkjet recording device of 1st Embodiment of this invention in a maintenance state. FIG. 2 is a schematic perspective view illustrating a conveyance belt and the vicinity thereof in the ink jet recording apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic front view showing a conveyance belt and its vicinity of the ink jet recording apparatus according to the first embodiment of the present invention. It is a perspective view which shows the drive roller and driven roller of the inkjet recording device of 1st Embodiment of this invention. It is a top view which shows the drive roller and driven roller of the inkjet recording device of 1st Embodiment of this invention. FIG. 5 is a schematic front view showing a conveyance belt and its vicinity of an inkjet recording apparatus according to a modification of the first embodiment of the present invention. It is a schematic front view which shows the conveyance belt of the inkjet recording device of 2nd Embodiment of this invention, and its vicinity. FIG. 2 is a perspective view illustrating a driving roller, a driven roller, and a support member of the ink jet recording apparatus according to the first embodiment of the present invention. It is a schematic front view which shows the conveyance belt of the inkjet recording device of 3rd Embodiment of this invention, and its vicinity. It is a schematic front view which shows the conveyance belt and its vicinity of the inkjet recording device of 4th Embodiment of this invention. It is a perspective view which shows the drive roller and driven roller of the inkjet recording device of 4th Embodiment of this invention. It is a top view which shows the drive roller and driven roller of the inkjet recording device of 4th Embodiment of this invention. It is a perspective view which shows the drive roller and driven roller of the modified example inkjet recording device of 4th Embodiment of this invention. It is a perspective view which shows another example of the drive roller applicable to this invention, and a driven roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Inkjet recording device 14 Housing | casing 16 Paper feed tray 18 Pickup roller 20 Conveyance roller pair 22 Conveyance path 24 Drive roller 24 'Drive roller 26 Driven roller 26' Followed roller 28 Conveyor belt 28F Flat part 30 Recording head array 32 Inkjet recording head 32N Nozzle surface 34 Maintenance unit 36 Suction / charging roller 40 Peeling plate 42 Ejection roller pair 44 Ejection path 46 Ejection tray 50 Reversing roller pair 52 Reversal path 54 Ink tank 56 Peeling claw 58 Shaft member 60 Charger 62 Shaft 64 Roller disk 64 'Roller disc 64' Roller disc 66 Recess 68 Auxiliary roller 70 Support member 70A Center portion 70B Branch portion 72 Drive roller 74 Driven roller CL Center line L Center pitch P Paper R1 Radius R2 Radius SE Discharge area θ Lap angle

Claims (7)

A transport belt formed endlessly and capable of circulating while holding a recording medium on the outer peripheral surface;
A driving roller that is disposed in contact with the conveyor belt inside the conveyor belt and applies a circulation driving force to the conveyor belt;
A driven roller that is arranged in contact with the conveyor belt at a predetermined inter-axis pitch with the drive roller inside the conveyor belt and rotates following the circulation of the conveyor belt;
An ink jet recording head disposed opposite to a flat portion of the conveyor belt configured between the driving roller and the driven roller and ejecting ink droplets according to image information on a recording medium on the flat portion;
With
A recess that overlaps at least one of the driving roller and the driven roller with the other partially entering the roller when viewed in the axial direction;
An ink jet recording apparatus comprising: At least one of the driving roller and the driven roller is provided with a roller disk that is arranged in plural at predetermined intervals along the axial direction and contacts the transport belt on the outer peripheral surface,
The inkjet recording apparatus according to claim 1, wherein the recess is configured as a gap between the plurality of roller disks. Both the driving roller and the driven roller include a plurality of the roller disks in which the concave portions are alternately configured in the axial direction,
The inkjet recording apparatus according to claim 2, wherein the driving roller and the driven roller are alternately inserted into the concave portion. A support member that is disposed in a region of the recess where the driving roller or the driven roller does not enter and supports the conveyor belt from the inside;
The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus includes:   The inkjet recording according to any one of claims 1 to 4, wherein the driving roller and the driven roller are symmetrically formed in a width direction orthogonal to a conveyance direction of the recording medium. apparatus.   A plurality of the inkjet recording heads are provided so as to face each of at least two flat portions of the plurality of flat portions of the transport belt configured between the driving roller and the driven roller. The ink jet recording apparatus according to any one of claims 1 to 5, wherein the ink jet recording apparatus is characterized.   7. The ink jet recording head according to claim 1, wherein the ink jet recording head has a width capable of ejecting ink droplets with respect to the entire width of the recording medium in a width direction orthogonal to the conveyance direction of the recording medium. 2. An ink jet recording apparatus according to item 1.

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