Drying device and image forming system

Abstract

To provide a drying device and an image forming system capable of suppressing curling of a sheet accompanying with progress of drying.SOLUTION: A drying device includes: a conveying belt 61 which is formed with a through hole on the whole surface and which supports a medium and conveys the medium in a predetermined conveying direction; a heating unit 13 which dries the image by blowing hot air onto the medium and presses the medium against the conveying belt 61 by the hot air; and a suction unit 17 for attracting the medium to the conveying belt 61 by sucking air through the through hole. At least one of force for pressing the medium against the conveying belt 61 by the suction unit 13 and force for attracting the medium to the conveying belt 61 by the suction unit 17 is larger on a downstream side than the force on an upstream side in the conveying direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a drying device that dries a recording medium on which an image has been formed while conveying the same, and to an image forming system that includes the drying device. [Background technology]

[0002] An image forming system including an inkjet type image forming apparatus is provided with a drying device that dries an image formed on a recording medium. The drying device described in Patent Document 1 includes a conveying means for conveying the recording medium, a dry air spraying means for spraying dry air onto the front side of the conveyed recording medium, and a negative pressure suction means for sucking the back side of the recording medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-285877 A Summary of the Invention [Problem to be solved by the invention]

[0004] When drying an image while transporting a recording medium, as in the drying device of Patent Document 1, the influence of the ink on the paper varies as the drying progresses, in other words, as the paper is transported from the upstream side to the downstream side. For example, there is a problem that the more the drying progresses, that is, the more downstream the paper is, the more likely it is to curl due to the drying of the ink.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In consideration of the above circumstances, an object of the present invention is to provide a drying device and an image forming system that can suppress curling of paper that occurs as the drying process progresses. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the drying device of the present invention is a drying device that dries a medium on which an image is formed while transporting it, and is equipped with a transport belt having through holes formed on its entire surface to support the medium and transport it in a predetermined transport direction, a heating section that blows warm air onto the medium to dry the image and presses the medium against the transport belt with the warm air, and a suction section that attracts the medium to the transport belt by sucking air through the through holes, and is characterized in that at least one of the force with which the heating section presses the medium against the transport belt and the force with which the suction section attracts the medium to the transport belt is greater on the downstream side of the transport direction than on the upstream side.

[0007] In the drying device of the present invention, the heating section may include a blower fan that takes in outside air and blows it toward the conveying belt, a straightening member that is positioned downstream of the blower fan in the blowing direction of the blower fan and has a large number of through holes formed therein, and a heater that is positioned downstream of the straightening member in the blowing direction, and may be characterized in that the dimensions of the large number of through holes formed in the straightening member are larger on the downstream side in the conveying direction than on the upstream side.

[0008] In the drying device of the present invention, the heating section may be provided with a reflector plate having a large number of through holes formed therein, which reflects infrared rays radiated from the heater toward the conveying belt, and the dimensions of the large number of through holes formed in the reflector plate may be larger on the downstream side in the conveying direction than on the upstream side.

[0009] In the drying device of the present invention, the suction section may include a plurality of compartments separated along the conveying direction, and a suction fan having the same air volume for sucking in each of the plurality of compartments, and the volume of the plurality of compartments may be smaller on the downstream side of the conveying direction than on the upstream side.

[0010] The image forming system of the present invention is characterized by comprising an image forming device that forms an image on a medium, and a drying device that dries the medium on which the image has been formed by the image forming device while transporting the medium. Effect of the Invention

[0011] According to the present invention, the force pressing and attracting the recording medium to the conveying belt is greater on the downstream side of the conveying direction where the ink dries, thereby preventing the paper from floating up or moving and preventing curling. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a schematic diagram of an image forming system according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing the inside of a drying device according to an embodiment of the present invention. [Diagram 3] 2 is a front view showing a heating section, a conveying section, and a suction section of the drying device according to the embodiment of the present invention. FIG. [Figure 4] 2 is an enlarged front view showing a portion of a heating unit, a conveying unit, and a suction unit of the drying device according to the embodiment of the present invention. FIG. [Diagram 5] 2 is an enlarged perspective view showing a portion of a heating unit, a conveying unit, and a suction unit of a drying device according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming system and a drying device according to an embodiment of the present invention will now be described with reference to the drawings.

[0014] First, an image forming system including a drying device will be described with reference to Fig. 1. Fig. 1 is a front view showing the image forming system. L, R, Fr, and Rr appropriately attached to each figure indicate the left side, right side, front side, and rear side of the image forming system, respectively.

[0015] The image forming system 1 includes a paper feeder 3, an image forming device 5, a drying device 7, and a post-processing device 9. The paper feeder 3 stores paper and feeds the paper to the image forming device 5. The image forming device 5 is disposed to the left of the paper feeder 3, and forms an image on the paper fed from the paper feeder 3 by an inkjet method. The drying device 7 is disposed to the left of the image forming device 5, and dries the paper on which an image has been formed while transporting it. The post-processing device 9 is disposed to the left of the drying device 7, and performs post-processing on the paper dried by the drying device 7. Paper is an example of a recording medium.

[0016] Next, the drying device 7 will be described with reference to Fig. 2 to Fig. 5. Fig. 2 is a front view showing the inside of the drying device, Figs. 3 and 4 are front views showing the heating section, the conveying section and the suction section, and Fig. 5 is a perspective view showing the heating section, the conveying section and the suction section.

[0017] As shown in Fig. 2, the drying device 7 includes a box-shaped housing 11. The housing 11 has a rectangular parallelepiped hollow portion surrounded by a top plate, a bottom plate, front and rear side plates, and left and right side plates. A heating unit 13, a conveying unit 15, and a suction unit 17 are accommodated on the image forming device 5 side (right side) of the hollow portion. A cooling unit 19 is accommodated above the post-processing device 9 side (left side) of the hollow portion of the housing 11.

[0018] An inlet 21 is formed at the top of the right side panel (the side panel on the image forming device 5 side) of the housing 11, through which paper (medium) is received from the image forming device 5. An outlet 23 is formed at the top of the left side panel (the side panel on the post-processing device 9 side) through which paper is passed to the post-processing device 9. The paper is transported by the transport section 15 and the cooling section 19 along the transport direction X from the inlet 21 to the outlet 23. In the following description, the upstream side and the downstream side respectively refer to the upstream side and the downstream side in the paper transport direction X. In addition, the direction perpendicular to the transport direction X is defined as the width direction.

[0019] Next, a description will be given of the heating section 13. As shown in Fig. 3 and Fig. 4, the heating section 13 includes a plurality of blower fans 31, a heater unit 33, and a case 35 in which the plurality of blower fans 31 are supported and in which the heater unit 33 is housed.

[0020] The case 35 is formed in a box shape with an open bottom, and has a hollow portion that is long in the conveying direction and is surrounded by a top plate, front and rear side plates, and left and right side plates. A plurality of exhaust ports (six in this example) (not shown) are formed in the top plate. An exhaust fan 39 (see FIG. 2) is connected to each exhaust port via a duct 37. When each exhaust fan 39 is driven, the air inside the case 35 is exhausted, and the air in the hollow portion of the case 35 is circulated.

[0021] A plurality of blower fans 31 (12 in this example) are supported on the upper plate of the case 35. The plurality of blower fans 31 are arranged in two rows of six each along the transport direction X. The intervals between adjacent blower fans 31 in the transport direction X and the width direction are approximately equal. The plurality of blower fans 31 have the same air volume, take in outside air, and blow the taken-in outside air into the hollow part of the case 35.

[0022] The heater unit 33 includes a plurality of infrared heaters 41 (24 in this example), a plurality of reflecting plates 43 (24 in this example), and a housing 45 in which the plurality of heaters 41 and the reflecting plates 43 are housed.

[0023] The housing 45 is formed in a box shape with an open bottom, and has a hollow portion that is long in the conveying direction and is surrounded by a top plate 45a, front and rear side plates, and left and right side plates. As shown in FIG. 5, a large number of through holes 51 are opened on one surface of the top plate 45a. The large number of through holes 51 are arranged in a staggered manner with equal density. The size (diameter) of the through holes 51 formed in a predetermined area A (see FIG. 3, for example, a portion having a length of 1 / 4 of the length of the top plate 45a along the conveying direction X, hereinafter simply referred to as the downstream area A) on the heating unit 13 is larger than the size (diameter) of the through holes 51 formed in other parts. The top plate 45a is an example of a straightening member in which a large number of through holes are formed, and straightens the air taken into the case 35 by the blower fan 31 so as to be directed downward.

[0024] 4, each heater 41 has, for example, a thin carbon filament 55 and a glass tube 57 housing the filament 55. The filament 55 radiates infrared rays in all directions (360 degrees) in the radial direction. The heaters 41 are arranged at equal intervals along the conveying direction X in an orientation along the width direction.

[0025] The reflector 43 has a U-shape opening downward when viewed in the width direction, and has a substantially rectangular upper wall and side walls that bend downward at substantially right angles from both long sides of the upper wall. A large number of through holes 59 are formed in the upper wall. As shown in FIG. 5, the large number of through holes 59 are arranged in a staggered manner with equal density. The size (diameter) of the through holes 59 of the reflector 43 arranged in the downstream region A (see FIG. 3) is larger than the size (diameter) of the through holes 59 formed in other parts. The reflector 43 is arranged above the heater 41 and reflects infrared rays emitted from the filament 55 downward.

[0026] Next, the conveying section 15 will be described. As shown in Fig. 3 and Fig. 4, the conveying section 15 includes a conveying belt 61 and a frame 63 that supports the conveying belt 61. The frame 63 has front and rear side plates that are long in the conveying direction X and are arranged at a predetermined interval in the front-rear direction. A driving roller 65 is rotatably supported between the upstream ends of the front and rear side plates, and a driven roller 67 is rotatably supported between the downstream ends.

[0027] The conveyor belt 61 is an endless belt, and has many through holes (not shown) formed on the entire surface. The conveyor belt 61 is wound around a driving roller 65 and a driven roller 67. When the driving roller 65 is driven, the conveyor belt 61 circulates and runs in the counterclockwise direction in Figs. 2 to 4. The outer surface of the conveyor belt 61 along the upper track (direction from the upstream side to the downstream side) becomes the conveying surface 61a along which the paper is conveyed. The conveyor belt 61 running on the upper track is supported by a conveying plate 69 supported by front and rear side plates. The conveying plate 69 has through holes 71 (see Fig. 4) formed on the entire surface. When the conveyor belt 61 runs, the back surface of the conveyor belt 61 running on the upper track (the surface behind the conveying surface 61a) slides along the conveying plate 69.

[0028] 2 and 3, the conveying section 15 is formed to be longer upstream in the conveying direction X than the heating section 13. In detail, the upstream end of the conveying surface 61a of the conveying belt 61 extends upstream of the upstream end of the heating section 13 and upstream of the receiving port 21. The downstream end of the conveying surface 61a is located at approximately the same position as the downstream end of the heating section 13, and is connected to the cooling section 19.

[0029] Next, the suction unit 17 will be described. As shown in Fig. 3 and Fig. 4, the suction unit 17 is provided in the hollow portion of the conveyor belt 61. The suction unit 17 includes a partition plate 83 and a plurality of suction fans 85 (three in this example) supported by the partition plate 83. The partition plate 83 has a bottom plate and partition walls surrounding the four sides, and divides the hollow portion into a plurality of sections S1, S2, S3 (three in this example) along the conveyor direction X as shown in Fig. 3. The upper surface of each section is open and faces the conveyor plate 69.

[0030] The volume of the section S3 on the most downstream side in the conveying direction X is smaller than the volumes of the other sections S1 and S2. That is, the bottom area of ​​the section S1 on the downstream side in the conveying direction X is smaller than the bottom area of ​​the other sections S2 and S3.

[0031] The suction fans 85 are attached to the bottom plate of the partition plate 83 in correspondence with each compartment. The multiple suction fans 85 have the same air volume. When the suction fans 85 are driven, air in the space above the conveyor belt 61 (conveyor surface 61a) traveling on the upper track is taken into each compartment through the through holes of the conveyor belt 61 and the through holes 71 of the conveyor plate 69.

[0032] An example of the drying operation of the drying device 7 having the above configuration will be described with reference to Fig. 2 to Fig. 5. A sheet on which an image has been formed by the image forming device 5 (see Fig. 1) is received by the conveying section 15 through the receiving opening 21 of the drying device 7. As described above, since the upstream end of the conveying surface 61a of the conveyor belt 61 extends upstream of the receiving opening 21, the sheet discharged from the image forming device 5 is placed on the conveying surface 61a of the conveyor belt 61.

[0033] In the transport section 15, the drive roller 65 is driven to rotate and the transport belt 61 runs. As a result, the paper placed on the transport surface 61a is transported into the housing 11 through the receiving opening 21.

[0034] Furthermore, the blower fan 31 and heater unit 33 of the heating section 13 are driven. The air taken into the hollow portion of the case 35 by the blower fan 31 is blown downward. Then, the air passes through a through hole 51 formed in a top plate 45a of the housing 45 of the heater unit 33 and enters the housing 45 (see arrow A1 in FIG. 4). In the housing 45, as the heater unit 33 is driven, infrared rays are emitted from each heater 41 in all directions. The infrared rays emitted upward from the heater 41 are reflected downward by the reflector 43.

[0035] The air that has entered the housing 45 is blown further downward through the through holes 59 in the reflector 43 of the heater unit 33 (see arrow A2 in FIG. 4), and is heated by infrared rays radiated from the heater 41. The air heated in this manner is blown onto the paper transported along the transport surface 61a of the transport belt 61, drying the ink. The paper is then pressed against the transport surface 61a by the blown air. Hereinafter, the force with which the paper is pressed against the transport surface 61a in the heating section 13 is referred to as the pressing force.

[0036] Furthermore, the suction fan 85 of the suction unit 17 is driven. As a result, as described above, air in the space above the conveyor belt 61 traveling on the upper track is taken in through each section via the through holes of the conveyor belt 61 and the through holes 71 of the conveyor plate 69 (see arrow A3 in FIG. 4), creating a negative pressure above the conveyor surface 61a. Then, the paper conveyed on the conveyor surface 61a of the conveyor belt 61 is attracted to the conveyor surface 61a. Hereinafter, the force that attracts the paper to the conveyor surface 61a in the suction unit 17 is referred to as the attraction force.

[0037] As the paper is transported from the upstream side to the downstream side along the transport surface 61a, the ink is dried by the heating unit 13. As described above, in the downstream region A, the diameter of the through hole 51 formed in the top plate 45a of the housing 45 and the diameter of the through hole 59 formed in the reflecting plate 43 are larger than the diameters of the other through holes, so that a large amount of air passes through the top plate 45a and the reflecting plate 43. That is, a large amount of hot air is blown onto the paper on the transport surface 61a, and the pressing force becomes large.

[0038] Furthermore, the suction section 17 is formed such that the volume of the section S3 on the most downstream side in the conveying direction X is smaller than the volumes of the other sections S1 and S2. Since the suction fan 85 has the same air volume, the smaller the volume of the section, the stronger the attracting force. In this way, the pressing force and the attracting force are stronger on the downstream side of the conveying surface 61a.

[0039] In addition, while the paper is transported on the transport surface 61a, the inside of the case 35 of the heating section 13 and the inside of the housing 45 of the heater unit 33 become a high-humidity and high-temperature environment, so the exhaust fan 39 (see Figure 1) is driven to circulate the air.

[0040] The paper transported downstream along the transport surface 61a is transported to the cooling section 19 (see Figure 1), and after being cooled in the cooling section 19, is transported through the discharge outlet 23 to the post-processing device 9 (see Figure 1).

[0041] As is clear from the above description, according to the drying device 7 of the present invention, the pressing force and the attracting force are increased on the downstream side of the transport surface 61a where the drying of the ink progresses. As described above, as the drying of the ink progresses, in other words, as the paper is transported from the upstream side to the downstream side, curling is more likely to occur in the paper. Therefore, by increasing the pressing force and the attracting force on the downstream side, it is possible to prevent the paper from floating up or moving from the transport surface 61a and prevent curling.

[0042] On the other hand, on the upstream side, the ink is not dried sufficiently, and color shifts and the like are likely to occur. For this reason, it is not preferable for the paper to be strongly attracted to the conveying surface 61a. In the present invention, the pressing force and the attracting force are increased only on the downstream side, so color shifts do not occur and curling can be prevented.

[0043] In the above embodiment, the diameter of the through hole 51 formed in the top plate 45a and the through hole 59 formed in the reflector plate 43 is made larger than the diameter of the other through holes in the downstream region A, thereby increasing the pressing force on the downstream side. This allows the air volume of the multiple blower fans 31 to be constant, making it easier to select and control the blower fans 31. The diameters of the through holes 51 and 59 may be constant, and the holes may be arranged at a higher density on the downstream side than on the upstream side. Furthermore, the diameters of the through holes 51 and 59 may be constant, and the air volume of the most downstream blower fan 31 may be increased.

[0044] In addition, in the suction section 17, the downstream section S3 is made smaller in volume than the other sections, thereby increasing the downstream attraction force. This allows the airflow of the multiple suction fans 85 to be constant, making it easier to select and control the suction fans 85. The bottom area of ​​all sections may be kept constant, and the height of the downstream section S3 may be lowered. Alternatively, the diameter of the through hole 71 of the conveying plate 69 facing the downstream section S3 may be made smaller than the diameter of the portion facing the other sections. In these cases, the downstream attraction force can also be increased. Furthermore, the volume of the sections may be kept constant, and the airflow of the most downstream suction fan 85 may be increased.

[0045] In addition, in this embodiment, both the pressing force of the heating section 13 and the attracting force of the suction section 17 are made higher on the downstream side than on the upstream side, but either the pressing force of the heating section 13 or the attracting force of the suction section 17 may be made higher on the downstream side than on the upstream side.

[0046] In this embodiment, the pressing force of the heating unit 13 and the attracting force of the suction unit 17 are made higher in the downstream portion, but they may be made to gradually increase from the upstream side to the downstream side.

[0047] Although the present invention has been described with respect to a specific embodiment, the present invention is not limited to the above embodiment. The above embodiment may be variously changed, substituted, or modified without departing from the scope and spirit of the present invention, and the claims include all embodiments that may be included within the scope of the technical idea. [Explanation of symbols]

[0048] 1. Image forming system 5. Image forming device 7 Drying equipment 13 Heating section 17 Suction part 31 Blower fan 41 Heater 43 Reflector 45a Top plate (flow straightening member) 51 Through hole 59 Through hole 61 Conveyor Belt 85 Suction fan S1, S2, S3 compartments

Claims

1. A drying device that dries a medium on which an image is formed while conveying the medium, comprising: a conveyor belt having through holes formed on its entire surface and supporting the medium and conveying it in a predetermined conveying direction; a heating section that blows hot air onto the medium to dry the image and presses the medium against the conveyor belt with the hot air; a suction unit that attracts the medium to the conveyor belt by sucking air through the through hole, The heating unit includes: a blower fan that takes in outside air and blows it toward the conveyor belt; a straightening member having a large number of through holes formed therein, the straightening member being disposed downstream of the blower fan in the blowing direction of the blower fan; a heater disposed downstream of the airflow straightening member in the airflow direction, the through holes formed in the flow straightening member are formed to have a larger size on a downstream side in the conveying direction than on an upstream side, A drying device, characterized in that at least one of the force with which the heating section presses the medium against the conveying belt and the force with which the suction section attracts the medium to the conveying belt is greater downstream in the conveying direction than upstream.

2. The heating unit includes: a reflector having a large number of through holes formed therein, the reflector reflecting infrared rays emitted from the heater toward the conveyor belt; 2. The drying device according to claim 1, wherein the size of the multiple through holes formed in the reflecting plate is larger on a downstream side in the conveying direction than on an upstream side.

3. A drying device that dries a medium on which an image is formed while transporting the medium, comprising: a conveyor belt having through holes formed on its entire surface and supporting the medium and conveying it in a predetermined conveying direction; a heating section that blows hot air onto the medium to dry the image and presses the medium against the conveyor belt with the hot air; a suction unit that attracts the medium to the conveyor belt by sucking air through the through hole, The suction unit is A plurality of sections separated along the conveying direction; a suction fan having the same air volume for sucking in each of the plurality of compartments; The volume of each of the compartments is smaller on the downstream side in the conveying direction than on the upstream side, A drying device, characterized in that at least one of the force with which the heating section presses the medium against the conveying belt and the force with which the suction section attracts the medium to the conveying belt is greater downstream in the conveying direction than upstream.

4. an image forming device for forming an image on a medium; 4. An image forming system comprising: the drying device according to claim 1, which dries a medium on which an image has been formed by the image forming apparatus while conveying the medium.

Images