Sheet drying apparatus and image forming system including the same

Abstract

To provide a sheet drying apparatus which prevents occurrences of blisters without deteriorating a sheet conveyance state and reducing safety, and provide an image forming system including the sheet drying apparatus.SOLUTION: A sheet drying apparatus includes a conveyance portion, a drying portion, and a preliminary drying portion. The conveyance portion conveys a sheet on which an image is formed with inks containing moisture. The drying portion is arranged facing the conveyance portion and heats and dries the sheet. The preliminary drying portion is arranged adjacently upstream of the drying portion with respect to a conveyance direction of the sheet, and preliminarily dries the sheet.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a sheet drying device for drying a sheet on which an image is printed by an inkjet recording device or the like, and an image forming system including the same.

Background Art

[0002] Conventionally, as a recording device such as a facsimile machine, a copying machine, or a printer, an inkjet recording device that discharges ink onto a sheet to form an image has been widely used. Further, a sheet drying device that heats and dries a sheet (paper) to which ink has been attached by an inkjet recording device is known.

[0003] In a sheet drying device, if an attempt is made to rapidly dry the ink adhering to the sheet, moisture inside the paper may evaporate and blisters may occur. Therefore, various methods for suppressing blisters have been proposed. For example, Patent Document 1 discloses adjusting the temperature of the hot air blown onto the printing paper passing through the printing drying device by the calorific value of the burner that generates the hot air.

[0004] Patent Document 2 discloses an inkjet printer having an inkjet recording head, a drying means for drying the ink of an image-receiving medium on which an image has been recorded by the inkjet recording head, a detection means for the absolute humidity inside the device, and a measurement means for the environmental temperature and humidity, and the drying means sets the drying conditions by the drying means according to the absolute humidity and environmental temperature and humidity inside the device, and improves the drying ability during continuous recording.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As in Patent Documents 1 and 2, measures have been taken to prevent blistering by adjusting the calorific value of the warm air blown onto the sheet. However, there are problems such as the sheet being curled due to changes in the air volume, or the safety being reduced by making the calorific value variable.

[0007] In view of the above problems, an object of the present invention is to provide a sheet drying device capable of suppressing the occurrence of blistering without reducing the conveyance state or safety of the sheet, and an image forming system including the same.

Means for Solving the Problems

[0008] To achieve the above object, a first configuration of the present invention is a sheet drying device including a conveyance unit, a drying unit, and a preliminary drying unit. The conveyance unit conveys a sheet on which an image is formed using ink containing moisture. The drying unit is disposed opposite to the conveyance unit and heats and dries the sheet. The preliminary drying unit is disposed adjacent to the upstream side of the drying unit with respect to the conveyance direction of the sheet and preliminarily dries the sheet.

Effects of the Invention

[0009] According to the first configuration of the present invention, by providing a preliminary drying unit that raises the temperature of the sheet and performs preliminary drying on the upstream side of the drying unit with respect to the conveyance direction of the sheet, it is possible to suppress the occurrence of blistering without reducing the conveyance state or safety of the sheet.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] [1. Configuration of an Image Forming System Including a Sheet Drying Apparatus] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the internal configuration of an image forming system 200 including the sheet drying apparatus 10 of the present invention. FIG. 2 is a side cross-sectional view of the periphery of the drying unit 40 of the sheet drying apparatus 10 according to an embodiment of the present invention. With reference to FIGS. 1 and 2, an image forming system 200 including an image forming apparatus 100 and a sheet drying apparatus 10 will be described.

[0012] The image forming apparatus 100 is an inkjet recording type printer, and includes a paper feeding unit 2 disposed at the lower part of the image forming apparatus 100, an image forming unit 3 disposed above the paper feeding unit 2, and a paper feeding unit 4 that feeds the paper P accommodated in the paper feeding unit 2 to the image forming unit 3.

[0013] The image forming unit 3 includes a recording unit 3a having a plurality of recording heads and a printing conveyance unit 3b disposed opposite to the recording unit 3a. The printing conveyance unit 3b includes an endless printing conveyance belt 5 wound around a plurality of rollers including a drive roller. The paper P conveyed by the paper feeding unit 4 passes below the recording unit 3a while being adsorbed and held on the printing conveyance belt 5 by a paper suction unit (not shown) provided inside the printing conveyance belt 5. The paper P on which a predetermined image is recorded by the image forming unit 3 is discharged from the discharge roller pair 6 and carried into the sheet drying device 10.

[0014] The sheet drying device 10 is disposed adjacent to the image forming device 100 and dries the ink on the paper P discharged from the image forming device 100. The sheet drying device 10 includes a first conveyance unit 20, a preliminary drying unit 30, a drying unit 40, a suction fan unit 50, and a second conveyance unit 70.

[0015] The first conveyance unit 20 includes a drive roller 21a, a driven roller 21b, and a conveyance belt 22. The conveyance belt 22 is wound around a drive roller 21a disposed on the downstream side with respect to the conveyance direction of the paper P (the direction from right to left in FIG. 1, hereinafter simply referred to as the conveyance direction) and a driven roller 21b disposed on the upstream side.

[0016] Paper suction parts 23a and 23b are arranged inside the conveyance belt 22. The conveyance belt 22 is formed with a number of suction holes (not shown) through which suction air for adsorbing the paper P to the conveyance belt 22 by negative pressure suction by the paper suction parts 23a and 23b passes.

[0017] Belt cooling fans 24 are arranged at two positions below the conveyance belt 22. A belt temperature sensor 25 is arranged in contact with and separated from the lower surface of the conveyance belt 22. The belt cooling fan 24 blows cooling air to the conveyance belt 22 when the temperature detected by the belt temperature sensor 25 becomes equal to or higher than a predetermined temperature.

[0018] The preliminary drying unit 30 is arranged closest to the downstream side of the sheet inlet 61 in the conveyance direction, and preliminarily dries the ink on the paper P carried in from the sheet inlet 61. The preliminary drying unit 30 includes a paper blowing fan 31 and a paper blowing duct 32 for blowing air onto the paper P from above.

[0019] The drying unit 40 is arranged adjacent to the downstream side of the preliminary drying unit 30 in the conveyance direction, and dries the ink on the paper P that has passed through the preliminary drying unit 30. The drying unit 40 includes two heating units 41 arranged so as to face the upper surface of the conveyance belt 22.

[0020] The suction fan unit 50 sucks the water vapor generated from the paper P passing through the drying unit 40. The suction fan unit 50 includes a suction fan 51 that sucks the air containing water vapor in the drying unit 40, and a separation fan 52 that blows separation air for separating the paper P from the conveyance belt 22. The suction fan unit 50 communicates with the space between the conveyance belt 22 and the heating unit 41 via the first duct 53, and communicates with the exhaust port 60 formed in the upper part of the sheet drying device 10 via the second duct 54.

[0021] Also, a plurality of outside air introduction fans 63 for taking in outside air are arranged at appropriate positions inside the sheet drying device 10. Sheet detection sensors 64 and 65 are arranged at the upstream and downstream parts of the first conveyance unit 20, respectively. The sheet detection sensors 64 and 65 detect that the paper P has passed through the sheet inlet 61 and the sheet outlet 62.

[0022] By the rotational drive of the drive roller 21a causing the conveyance belt 22 to rotate counterclockwise, the paper P carried in from the sheet inlet 61 sequentially passes through the preliminary drying unit 30 and the drying unit 40, and is discharged from the sheet outlet 62 to the outside of the sheet drying device 10, or is carried into the second conveyance unit 70.

[0023] The second conveyance unit 70 is disposed below the drying unit 40 and the preliminary drying unit 30 with the first conveyance unit 20 interposed therebetween. The second conveyance unit 70 includes a reversing conveyance path 70a for inverting the front and back surfaces of the paper P on which the ink has been dried, and a duplex conveyance path 70b for returning the paper P with its front and back surfaces inverted to the image forming apparatus 100 when performing duplex printing on the paper P.

[0024] An arcuate retraction path 71 is provided on the downstream side (the left side in FIG. 1) of the suction fan unit 50 with respect to the conveyance direction. The retraction path 71 retracts and stocks the paper P (waste paper) that has become unnecessary due to printing defects or the like in the image forming apparatus 100.

[0025] [2. Configuration of Sheet Drying Device] FIG. 3 is an enlarged view of the drying unit 40 in FIG. 2. The drying unit 40 includes a heating unit 41 and a warm air fan 42 (see FIG. 2). Two sets of heating units 41 are arranged along the conveyance direction (arrow X direction). The heating unit 41 includes a heater 43 and a reflector 44.

[0026] The heater 43 is rod-shaped and extends in the sheet width direction (the direction perpendicular to the paper surface of FIG. 3, hereinafter simply referred to as the width direction) that is horizontally orthogonal to the conveyance direction. A plurality (12 in this embodiment) of heaters 43 are arranged in parallel along the conveyance direction in the heating unit 41. In this embodiment, an infrared heater is used as the heater 43.

[0027] The reflector 44 is a side view U-shaped reflector plate arranged to surround each heater 43 from above. The infrared rays emitted from the heater 43 are reflected downward by the inner surface of the reflector 44 and irradiated onto the paper P carried and conveyed by the conveyance belt 22. Thereby, the moisture in the ink on the paper P evaporates and dries, and the ink is fixed on the paper P.

[0028] The warm air fan 42 is disposed above the heating unit 41. More specifically, the warm air fan 42 is disposed to blow air upward toward the reflector 44. The air blown onto the reflector 44 by the warm air fan 42 is heated as it passes through the gaps between the reflectors 44 to become warm air, and flows into the gap (drying space) between the heating unit 41 and the conveyor belt 22.

[0029] If there is steam or water vapor in the gap between the heating unit 41 and the conveyor belt 22, the infrared rays emitted from the heater 43 and reflected by the reflector 44 will be absorbed by the steam or water vapor, and the drying ability of the ink on the paper P will be inhibited. Therefore, by blowing warm air into the gap between the heating unit 41 and the conveyor belt 22 with the warm air fan 42 to disperse and remove the steam or water vapor generated from the paper P, the drying property of the ink by the infrared rays can be maintained.

[0030] A first duct 53 for sucking the steam or water vapor generated from the paper P together with air is provided between the drying unit 40 and the suction fan unit 50. The first duct 53 extends from the gap between the heating unit 41 and the conveyor belt 22 to the suction fan 51 in the suction fan unit 50.

[0031] [3. Structure of the Preliminary Drying Unit] FIG. 4 is a cross-sectional perspective view showing the configuration around the preliminary drying unit 30 and the drying unit 40 of the sheet drying apparatus 10. FIG. 5 is a side cross-sectional view obtained by cutting along the conveying direction around the preliminary drying unit 30 and the drying unit 40.

[0032] As shown in FIGS. 4 and 5, the preliminary drying unit 30 is partitioned by a first partition wall 33 disposed upstream of the drying unit 40 in the conveying direction (arrow X direction), a second partition wall 34 horizontally extending upstream in the conveying direction from a substantially central portion in the vertical direction of the first partition wall 33, and the side frame 10a, the rear frame 10b, and the front frame (not shown) of the sheet drying apparatus 10.

[0033] On the side frame 10a, a paper blowing fan 31 is arranged. Three paper blowing fans 31 are arranged along the width direction of the side frame 10a above the second partition wall 34. A blowing duct 32 is connected to the paper blowing fan 31.

[0034] The blowing duct 32 extends into the preliminary drying section 30 from the paper blowing fan 31 toward the conveyor belt 22. At the tip of the blowing duct 32, a blowing port 32a that opens toward the downstream side in the conveying direction is formed.

[0035] The outside air taken in from outside the sheet conveying device 10 by the paper blowing fan 31 passes through the blowing duct 32 and is blown obliquely downward from the upstream side in the conveying direction (in the direction of the hatched arrow in FIG. 5) toward a region (non-suction region R) on the upstream side in the conveying direction from the paper suction section 23a of the conveyor belt 22 from the blowing port 32a. Thereby, the lifting of the rear end of the paper P delivered from the sheet inlet 61 to the conveyor belt 22 can be suppressed.

[0036] A gap 35 is formed between the lower end of the first partition wall 33 and the conveyor belt 22. The warm air blown into the gap between the heating unit 41 and the conveyor belt 22 by the warm air fan 42 passes through the gap 35 and flows into the preliminary drying section 30. The paper P passing through the preliminary drying section 30 is warmed by this warm air, and the paper P is preliminarily dried.

[0037] FIGS. 6 and 7 are side cross-sectional views taken along the conveying direction of the periphery of the preliminary drying section 30 and the drying section 40, and show the flow of warm air from the drying section 40 when the paper blowing fan 31 is in the off state and the on state, respectively. In FIGS. 6 and 7, the flow of warm air is indicated by white arrows.

[0038] The warm air blown downward from above into the gap between the heating unit 41 and the conveyor belt 22 by the warm air fan 42 changes its direction horizontally along the upper surface of the conveyor belt 22. Here, a front frame (not shown) and a rear frame 10b (see FIG. 4) are present on the front side and the rear side of the drying section 40. Therefore, the warm air flows along the upper surface of the conveyor belt 22 toward the upstream side (the right side in FIGS. 6 and 7) and the downstream side (the left side in FIGS. 6 and 7) in the conveying direction. The warm air flowing toward the upstream side in the conveying direction passes through the gap 35 at the lower end of the first partition wall 33 and flows into the pre-drying section 30.

[0039] When the paper blowing fan 31 is in the off state, as shown in FIG. 6, a part of the warm air flowing into the pre-drying section 30 flows downward through the suction holes (not shown) formed in the conveyor belt 22 due to the negative pressure suction by the suction section 23a. On the other hand, most of the warm air advances along the conveyor belt 22 toward the upstream side in the conveying direction within the pre-drying section 30 and flows out of the sheet drying device 10 from the sheet inlet 61. That is, since the warm air flowing from the drying section 40 into the pre-drying section 30 quickly flows out of the pre-drying section 30, the pre-drying efficiency of the paper P in the pre-drying section 30 decreases. When the paper blowing fan 31 is in the on state, as shown in FIG. 7, it is blown obliquely downward (in the direction of the hatched arrow in FIG. 7) toward the non-suction region R from the blowing port 32a of the blowing duct 32 on the downstream side in the conveying direction. As a result, the warm air flowing toward the sheet inlet 61 collides with the blowing air from the blowing duct 32, and the warm air changes its direction upward above the pre-drying section 30.

[0040]

[0041] Thereby, the warm air flowing out of the pre-drying section 30 becomes only the warm air flowing downward through the suction holes of the conveyor belt 22. Therefore, it is possible to suppress the heat in the pre-drying section 30 from being exhausted to the outside.

[0042] ​According to the configuration of the present embodiment, by providing a preliminary drying unit 30 that raises the temperature of the sheet P on the upstream side of the drying unit 40 in the conveyance direction to perform preliminary drying, it is possible to suppress the occurrence of cockling without degrading the conveyance state and safety of the sheet P.

[0043] In addition, the blowing air from the sheet blowing fan 31 that prevents the sheet P from lifting in the non-suction area R of the conveyance belt 22 and the warm air flowing in the preliminary drying unit 30 collide with each other from opposite directions, making it difficult for the warm air to flow out of the preliminary drying unit 30. Therefore, the preliminary drying efficiency of the sheet P in the preliminary drying unit 30 is improved.

[0044] In addition, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, as an example of the image forming system 200, a configuration in which the sheet drying device 10 is connected to the image forming apparatus 100 that is an inkjet printer is shown. However, it goes without saying that the sheet drying device 10 can be used independently without being connected to the image forming apparatus 100.

Industrial Applicability

[0045] The present invention can be used in a sheet drying device that dries a sheet on which an image is printed by an inkjet recording device or the like. By using the present invention, it is possible to provide a sheet drying device and an image forming system including the same that can suppress the occurrence of cockling without degrading the conveyance state and safety of the sheet.

Explanation of Reference Numerals

[0046] 10 Sheet drying device 20 First conveyance unit (conveyance unit) 22 Conveyance belt 30 Preliminary drying unit 31 Sheet blowing fan 32 Blowing duct 40 Drying unit 41 Heating unit 42 Warm air fan 43 Heater 44 Reflector 50 Suction Fan Unit 51 Suction Fan 52 Separation Fan 53 First Duct 54 Second Duct 60 Exhaust Port 61 Sheet Inlet 62 Sheet Outlet 100 Image Forming Apparatus 200 Image Forming System P Paper (Sheet) R Non-Suction Region

Claims

1. A conveying unit that conveys a sheet on which an image is formed using ink containing moisture, A drying unit that is disposed opposite to the conveying unit and heats and dries the sheet, In a sheet drying device comprising: A pre-drying unit that is disposed adjacent to the upstream side of the drying unit with respect to the conveying direction of the sheet and pre-dries the sheet, characterized in that the sheet drying device is provided with the pre-drying unit.

2. The drying unit includes: A heating unit having a plurality of infrared heaters disposed opposite to the conveying unit and a plurality of reflectors surrounding the infrared heaters from the direction opposite to the conveying unit, A hot air fan that is disposed on the side opposite to the conveying unit with the heating unit interposed therebetween and blows hot air heated when passing through the gaps of the reflectors toward the conveying unit, Comprising: The hot air blown toward the conveying unit passes through the gap of the partition wall formed between the drying unit and the pre-drying unit and flows into the pre-drying unit toward the upstream side in the conveying direction. The sheet drying device according to claim 1, characterized in that.

3. The conveying unit includes: A conveying belt that carries and conveys the sheet, A suction unit that adsorbs and holds the sheet on the conveying belt by performing negative pressure suction through a large number of suction holes formed in the conveying belt, Comprising: A sheet blowing fan that sucks air outside the sheet conveying device, A blowing duct that communicates the sheet blowing fan and the inside of the pre-drying unit, Comprising: The air sucked by the sheet blowing fan and passing through the blowing duct serves as blowing air that prevents the sheet from floating up in the non-suction region upstream of the suction unit of the conveying belt with respect to the conveying direction. It is blown obliquely downward into the non-suction region toward the downstream side in the conveying direction, The blowing air collides with the hot air that has flowed into the pre-drying unit. The sheet drying device according to claim 2, characterized in that.

4. An image forming device that performs image formation using ink containing moisture on a sheet, The sheet drying device according to any one of claims 1 to 3 that dries the sheet on which an image is formed by the image forming device, An image forming system comprising:

Images