Sheet drying apparatus and image forming system including the same

Abstract

To provide a sheet drying apparatus that can reliably sense lifting of a sheet without causing a sensing member to contact with a top surface of the sheet, and to provide an image forming system including the sheet drying apparatus.SOLUTION: A sheet drying apparatus includes a conveyance portion, a drying portion, and a sheet lifting sensing mechanism. The conveyance portion has a conveyance member that moves while holding a sheet having an image formed on it with inks containing moisture. The drying portion is arranged facing the conveyance member and heats and dries the sheet. The sheet lifting sensing mechanism senses lifting of the sheet from the conveyance member. The sheet lifting sensing mechanism includes: a sheet lifting sensor having a light emitter and a light receiver opposite each other in a width direction of the sheet horizontally orthogonal to the conveyance direction; and a sensing assist member that protrudes from above into a conveyance space above the conveyance member and that contacts a lifted part of the sheet to rotate the sheet in a horizontal direction. A distance from the conveyance member to the sensing assist member is smaller than a minimum height of the conveyance space.SELECTED DRAWING: Figure 7

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, it is necessary to rapidly dry the ink adhering to the paper conveyed by a conveyance belt. Therefore, it has been difficult to detect the presence or absence of the paper adsorbed and conveyed by the high-temperature conveyance belt.

[0004] As a method for detecting the floating of paper that causes a jam (paper jam), for example, Patent Document 1 discloses a pressing means for suppressing the lifting of the recording surface of the recording paper, a displacement detection unit for detecting a displacement of the pressing means equal to or more than a predetermined value according to the lifting of the recording surface of the recording paper, and a control unit for stopping the recording operation of the recording paper conveyance means and the operation of the recording unit based on the detection output from the displacement detection unit, and for operating the conveyance means to discharge the recording paper from the recording unit after stopping the operation of the recording paper conveyance means and the recording operation of the recording unit. An image recording device is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the configuration of Patent Document 1, the displacement of the pressing means for suppressing the floating of the paper before loading is monitored, and when a paper that has risen more than a specified level from the conveyance surface is conveyed, the operation is stopped. However, since the paper introduced into the drying section has undried ink attached thereto, there has been a problem that a method of bringing the detection means into contact with the upper surface of the paper cannot be adopted.

[0007] In view of the above problems, an object of the present invention is to provide a sheet drying apparatus capable of reliably detecting the floating of a sheet without bringing a detection member into contact with the upper surface of the sheet, and an image forming system including the same.

Means for Solving the Problems

[0008] A first configuration of the present invention for achieving the above object is a sheet drying apparatus including a conveyance section, a drying section, and a sheet floating detection mechanism. The conveyance section has a conveyance member that moves while holding a sheet on which an image is formed using ink containing moisture. The drying section is disposed opposite to the conveyance member and heats and dries the sheet. The sheet floating detection mechanism is disposed on the downstream side of the drying section with respect to the conveyance direction of the sheet, and detects the floating of the sheet from the conveyance member. The sheet floating detection mechanism includes a sheet floating detection sensor having a light emitting section and a light receiving section facing each other in the width direction of the sheet that is perpendicular to the conveyance direction horizontally, and a detection auxiliary member that protrudes upward from above into the conveyance space above the conveyance member and contacts the floating portion of the sheet to rotate the sheet in the horizontal direction. The distance from the conveyance member to the detection auxiliary member is smaller than the minimum height of the conveyance space.

Effects of the Invention

[0009] According to the first configuration of the present invention, by disposing the sheet floating detection sensor and the detection auxiliary member as the sheet floating detection mechanism, the floating portion of the sheet is brought into contact with the detection auxiliary member to rotate the sheet in the horizontal direction. Thereby, the optical path of the sheet floating detection sensor can be surely blocked by the floating portion of the sheet, and the floating of the sheet can be accurately detected.

Brief Description of the Drawings

[0010]

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Figure 11

[0011] [1. Configuration of an Image Forming System Including a Sheet Drying Device] 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 the image forming system 200 including the sheet drying device 10 of the present invention. FIG. 2 is a side cross-sectional view around the drying unit 40 of the sheet drying device 10 according to an embodiment of the present invention. With reference to FIGS. 1 and 2, the image forming system 200 composed of the image forming device 100 and the sheet drying device 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 driving 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 apparatus 100 and dries the ink on the paper P discharged from the image forming apparatus 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 driving roller 21a, a driven roller 21b, and a conveyance belt 22. The conveyance belt 22 is wound around the driving 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 the driven roller 21b disposed on the upstream side.

[0016] Paper suction parts 23a and 23b are disposed inside the conveyance belt 22. 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 are formed in the conveyance belt 22.

[0017] Belt cooling fans 24 are arranged at two locations below the conveying belt 22. Also, a belt temperature sensor 25 is arranged in contact with and separated from the lower surface of the conveying belt 22. The belt cooling fan 24 blows cooling air onto the conveying belt 22 when the temperature detected by the belt temperature sensor 25 reaches a predetermined temperature or higher.

[0018] The preliminary drying unit 30 is arranged immediately downstream of the sheet inlet 61 in the conveying 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 conveying 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 conveying 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 conveying belt 22. The suction fan unit 50 communicates with the space between the conveying belt 22 and the heating unit 41 via a first duct 53 and communicates with an exhaust port 60 formed at the upper part of the sheet drying device 10 via a 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 conveying 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, the conveyor belt 22 rotates counterclockwise, causing the sheet P carried in from the sheet inlet 61 to sequentially pass through the preliminary drying unit 30, the drying unit 40, and the suction fan unit 50, and be discharged outside the sheet drying device 10 from the sheet outlet 62 or carried into the second conveying unit 70.

[0023] The second conveying unit 70 is disposed below the drying unit 40 and the preliminary drying unit with the first conveying unit 20 interposed therebetween. The second conveying unit 70 includes a reversing conveyance path 70a for reversing the front and back surfaces of the sheet P with the ink dried, and a duplex conveyance path 70b for returning the sheet P with the front and back surfaces reversed to the image forming apparatus 100 when performing duplex printing on the sheet 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 sheet P (waste sheet) that has become unnecessary due to printing defects or the like in the image forming apparatus 100.

[0025] [2. Configuration of the 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 U-shaped reflector in side view that is 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 on the conveyor belt 22. As a result, the moisture in the ink on the paper P evaporates and dries, and the ink is fixed on the paper P.

[0028] The hot air fan 42 is arranged above the heating unit 41. More specifically, the hot air fan 42 is arranged to blow air upward toward the reflector 44. The air blown onto the reflector 44 by the hot air fan 42 is heated as it passes through the gaps between the reflectors 44 to become hot 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 hot air into the gap between the heating unit 41 and the conveyor belt 22 by the hot air fan 42 to disperse and remove the steam or water vapor generated from the paper P, the drying property of the ink by infrared rays can be maintained.

[0030] A first duct 53 is provided between the drying unit 40 and the suction fan unit 50 to suck the steam or water vapor generated from the paper P together with the air. 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. Configuration of Paper Floating Detection Mechanism] FIG. 4 is a side cross-sectional view near the boundary between the drying unit 40 and the suction fan unit 50 of the sheet drying device 10. FIG. 5 is an enlarged view around the paper floating detection mechanism 80 in FIG. 4. FIG. 6 is a plan view of the periphery of the paper floating detection mechanism 80 of the first conveyance unit 20 as viewed from above.

[0032] As shown in FIGS. 4 and 5, near the boundary between the drying section 40 and the suction fan unit 50, a paper floating detection mechanism 80 for detecting the lifting of the paper P conveyed by the conveyor belt 22 of the conveying section 20 is arranged. The paper floating detection mechanism 80 includes a paper floating detection sensor 81 and a detection auxiliary member 82.

[0033] As shown in FIG. 6, the paper floating detection sensor 81 is an optical sensor having a light emitting section 81a and a light receiving section 81b. The light emitting section 81a and the light receiving section 81b are arranged to face each other in the width direction (arrow YY' direction) perpendicular to the conveying direction (arrow X direction) with the conveyor belt 22 interposed therebetween. The paper floating detection sensor 81 detects the lifting of the paper P from the conveyor belt 22 when the paper P blocks the optical path L through which the light emitted from the light emitting section 81a enters the light receiving section 81b.

[0034] As shown in FIG. 5, the detection auxiliary member 82 is an L-shaped member in side view that is attached to the downstream end of the heating unit 41 with respect to the conveying direction. The detection auxiliary member 82 is arranged immediately upstream of the optical path L of the paper floating detection sensor 81 with respect to the conveying direction. The distance d1 between the detection auxiliary member 82 and the conveyor belt 22 (conveying surface) is smaller than the distance d2 between the separation guide 58, which is the minimum height of the conveying space S above the conveyor belt 22, and the conveyor belt 22.

[0035] As shown in FIG. 6, the detection auxiliary member 82 is arranged at a position displaced by a predetermined distance d3 from the center line O in the width direction of the paper P conveyed by the conveyor belt 22 to one side (arrow Y direction) in the width direction.

[0036] FIG. 7 is a plan view showing a state in which the floating of the paper P is detected by the paper floating detection mechanism 80. FIG. 8 is a schematic diagram showing the mechanism for detecting the floating of the paper P by the paper floating detection mechanism 80. When the paper P is conveyed in a state of being lifted from the conveyor belt 22 by a certain height (distance d1 or more), as shown in FIG. 7, the trailing edge Pa of the paper P on the downstream side in the conveying direction collides with the detection auxiliary member 82.

[0037] Since the detection auxiliary member 82 is arranged at a position deviated from the center in the width direction of the sheet P, the sheet P that has collided with the detection auxiliary member 82 rotates so that the edge Pa in the direction opposite to the sliding direction (arrow Y direction) of the detection auxiliary member 82 (arrow Y' direction) protrudes downstream as shown by the broken line in FIG. 7.

[0038] When the sheet P is lifted from the conveyance belt 22, if the lifted portion (bent portion) of the sheet P passes across the optical path L between the light emitting portion 81a and the light receiving portion 81b, there is a possibility that the lifting of the sheet P cannot be detected.

[0039] In the sheet floating detection mechanism 80 of the present embodiment, by rotating the sheet P by the detection auxiliary member 82, as shown in FIG. 8, the bent portion Pb of the sheet P blocks the optical path L between the light emitting portion 81a and the light receiving portion 81b. Thereby, the sheet floating detection sensor 81 can surely detect the lifting of the sheet P.

[0040] FIG. 9 is a side cross-sectional view showing a state where the sheet P is jammed around the sheet floating detection mechanism 80. When a jam (paper clogging) of the sheet P occurs near the drying unit 40, the user opens the exterior cover and the inner cover (both not shown) of the sheet drying device 10 after the drying unit 40 reaches a temperature below a predetermined temperature.

[0041] Then, as shown in FIG. 10, the heating unit 41 is raised to remove the jammed sheet P. At this time, since the detection auxiliary member 82 attached to the heating unit 41 also rises together with the heating unit 41, there is no possibility that the detection auxiliary member 82 will interfere with the jam processing.

[0042] According to the configuration of the present embodiment, by arranging the detection auxiliary member 82 immediately upstream of the sheet floating detection sensor 81 in the conveyance direction, the lifted portion of the sheet P is brought into contact with the detection auxiliary member 82 to rotate the sheet P. Thereby, the optical path of the sheet floating detection sensor 81 can be surely blocked, and the lifting of the sheet P can be accurately detected.

[0043] Further, by disposing the detection auxiliary member 82 at a position deviated from the center line O in the width direction of the sheet P, the sheet P in contact with the detection auxiliary member 82 can be reliably rotated. Further, by attaching the detection auxiliary member 82 to the heating unit 41 that can move up and down, the detection auxiliary member 82 can be lifted together with the heating unit 41 during jam processing of the sheet P, and the jam processing work can be easily performed.

[0044] FIG. 11 is a diagram showing a modified example of the detection auxiliary member 82. The detection auxiliary member 82 shown in FIG. 11 has a guide surface 82a inclined by a predetermined angle with respect to the conveyance direction. When the downstream edge Pa of the sheet P in the conveyance direction collides with the guide surface 82a, as shown by the broken line in FIG. 11, the edge Pa is inclined by a predetermined angle with respect to the conveyance direction along the guide surface 82a.

[0045] As a result, as shown in FIG. 8, the bent portion Pb of the sheet P blocks the optical path L between the light emitting portion 81a and the light receiving portion 81b. As a result, the paper floating sensor 81 can surely detect the floating of the sheet P. Further, since the sheet P is inclined along the guide surface 82a, the sheet P can be rotated along the guide surface 82a even when the detection auxiliary member 82 is disposed at a position overlapping the center line O in the width direction of the sheet P.

[0046] 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, the detection auxiliary member 82 is disposed immediately upstream of the paper floating sensor 81 in the conveyance direction. However, if the detection auxiliary member 82 can contact the floating portion of the sheet P and rotate the sheet P, the position of the detection auxiliary member 82 in the conveyance direction is not particularly limited.

[0047] However, if the detection auxiliary member 82 is too far away from the paper floating sensor 81 in the conveyance direction, there is a possibility that the optical path of the paper floating sensor 81 cannot be blocked when the floating portion of the sheet P contacts the detection auxiliary member 82. Therefore, it is preferable to dispose the detection auxiliary member 82 within a certain range upstream or downstream of the paper floating sensor 81 in the conveyance direction.

[0048] Also, 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, which 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

[0049] 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 that can reliably detect the lifting of a sheet without bringing a detection member into contact with the upper surface of the sheet, and an image forming system including the same.

Explanation of Reference Numerals

[0050] 10 Sheet drying device 20 First conveying unit (conveying unit) 22 Conveying belt (conveying member) 30 Preliminary drying unit 40 Drying unit 41 Heating unit 50 Suction fan unit 60 Exhaust port 61 Sheet inlet 62 Sheet outlet 70 Second conveying unit 80 Paper lifting detection mechanism (sheet lifting detection mechanism) 81 Paper lifting detection sensor (sheet lifting detection sensor) 81a Light emitting unit 81b Light receiving unit 82 Detection auxiliary member 82a Guide surface 100 Image forming apparatus 200 Image forming system P Paper (sheet) O Center line S Conveying space

Claims

1. A conveying unit having a conveying member that moves while holding a sheet on which an image is formed using ink containing moisture, A drying unit disposed opposite to the conveying member and heating and drying the sheet, In a sheet drying device comprising: A sheet floating detection mechanism for detecting the lifting of the sheet from the conveying member is provided on the downstream side of the drying unit with respect to the conveying direction of the sheet, The sheet floating detection mechanism, A sheet floating detection sensor having a light emitting unit and a light receiving unit facing each other in the width direction of the sheet that is perpendicular to the conveying direction horizontally, A detection auxiliary member that protrudes upward from the conveying space above the conveying member and contacts the lifted portion of the sheet to rotate the sheet horizontally, Having, A sheet drying device, characterized in that the distance from the conveying member to the detection auxiliary member is smaller than the minimum height of the conveying space.

2. The sheet drying device according to claim 1, wherein the detection auxiliary member is disposed at a position shifted in the width direction from the center line in the width direction of the sheet conveyed by the conveying member.

3. The sheet drying device according to claim 1, wherein the detection auxiliary member has a guide surface inclined by a predetermined angle with respect to the conveying direction.

4. The sheet drying device according to claim 1, wherein the detection auxiliary member is disposed immediately upstream of the sheet floating detection sensor with respect to the conveying direction.

5. The drying unit has a heating unit that can move up and down with respect to the conveying member, The sheet drying device according to claim 1, wherein the detection auxiliary member is fixed to the downstream end of the heating unit with respect to the conveying direction.

6. 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 5 that dries the sheet on which an image is formed by the image forming device, An image forming system comprising.

Images