Sheet drying apparatus and image forming system including the same

Abstract

To provide a sheet drying apparatus that can keep the volume of air in a drying space uniform and that can achieve uniform drying properties to prevent uneven drying, and to provide an image forming system including the sheet drying apparatus.SOLUTION: A sheet drying apparatus includes a conveyance portion and a 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 drying portion includes: a heating unit having a plurality of infrared heaters extending in a width direction horizontally orthogonal to a conveyance direction of the sheet and arranged parallel to each other along the conveyance direction, and a plurality of reflectors that surround the infrared heaters from a direction opposite to the conveyance portion; and a hot air fan arranged opposite to the conveyance portion across the heating unit and configured to blow toward the conveyance portion hot air heated as a result of air passing through gaps between the reflectors. As many reflectors as the infrared heaters are arranged such that each reflector surrounds one infrared heater individually.SELECTED DRAWING: Figure 4

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 copier, or a printer, an inkjet recording device that ejects ink onto a sheet to form an image has been widely used. Also, 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] As a sheet drying device, there is known one in which a reflector (reflecting plate) is arranged so as to surround a heater, and infrared rays emitted from the heater are efficiently irradiated onto the sheet by radiant heat from the reflector.

[0004] For example, Patent Document 1 discloses an ink drying device in which a reflector is arranged so as to surround a heater, a platen (reflector) is arranged at a position facing each other with a member to be dried interposed therebetween, and air is caused to flow from the upstream side to the downstream side of the member to be dried. It is described that partial concentration of thermal energy can be avoided, and thus burning of the recording medium due to overheating can be prevented without impairing the drying property.

[0005] Patent Document 2 discloses a drying device in which an opening of a reflector holder is closed by a plate material formed of heat-resistant glass, and the plate material is arranged parallel to the platen surface. By arranging the plate material, the air flow does not enter the reflector and generate turbulent flow, and the air flow passing around the reflector holder and guided to the platen surface is rectified through the air blowing space formed by the plate material and the platen. Therefore, it is described that the wind speed in the air blowing space becomes constant, and the recording paper can be dried evenly.

Prior Art Documents

Patent Document

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the configuration of Patent Document 1, it holds when the drying area is short, but when the drying area becomes long, it is difficult to control the air flow. In addition, it is necessary to separately provide dedicated suction fans on the upstream side and the downstream side of the drying area. Therefore, an increase in the replacement frequency of the suction fans can be considered, but in the conventional configuration, since the suction fans are fixed to the device, there is a problem that it takes time to replace the suction fans.

[0008] Similarly, in the configuration of Patent Document 2, it holds when the drying area is short, but when the drying area becomes long, it is difficult to control the air flow. In addition, since glass absorbs a fair amount of infrared rays, there is a problem of reducing the drying ability.

[0009] In view of the above problems, an object of the present invention is to provide a sheet drying device capable of maintaining a uniform air volume in the drying area even when the drying area becomes long, equalizing the dryness, and suppressing drying unevenness, and an image forming system including the same.

Means for Solving the Problems

[0010] In order to achieve the above object, a first configuration of the present invention is a sheet drying apparatus including a conveyance unit and a drying unit. The conveyance unit conveys a sheet on which an image is formed with ink containing moisture. The drying unit is disposed opposite to the conveyance unit and heats and dries the sheet. The drying unit includes a heating unit and a warm air fan. The heating unit extends in a width direction that is horizontally orthogonal to the conveyance direction of the sheet, and includes a plurality of infrared heaters arranged in parallel along the conveyance direction, and a plurality of reflectors that surround the infrared heaters from the opposite direction to the conveyance unit. The warm air fan is disposed on the side opposite to the conveyance unit with the heating unit interposed therebetween, and blows the warm air heated when passing through the gaps of the reflectors toward the conveyance unit. The plurality of reflectors are arranged in the same number as the infrared heaters so as to individually surround one infrared heater one by one.

Advantages of the Invention

[0011] According to the first configuration of the present invention, the sheet conveyed by the conveyance unit is heated by the infrared rays emitted from the infrared heaters and reflected by the reflectors, and the warm air blown from the gaps of the reflectors. Therefore, the ink on the sheet can be efficiently dried. Further, by surrounding one infrared heater with one reflector, the warm air can be uniformly flowed in the drying space, and the water vapor and steam existing in the drying space can be efficiently removed to maintain the drying performance of the ink by the infrared heaters.

Brief Description of the Drawings

[0012]

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[0013] [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 an 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, an image forming system 200 composed of an image forming apparatus 100 and a sheet drying device 10 will be described.

[0014] 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.

[0015] 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 apparatus 10.

[0016] The sheet drying apparatus 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 apparatus 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.

[0017] 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.

[0018] Paper suction portions 23a and 23b are disposed inside the conveyance belt 22. The conveyance belt 22 is formed with a number of suction holes (not shown) through which a suction wind for adsorbing the paper P to the conveyance belt 22 by negative pressure suction by the paper suction portions 23a and 23b passes.

[0019] Belt cooling fans 24 are arranged at two locations below the conveyor belt 22. Also, a belt temperature sensor 25 is arranged in contact with and separated from the lower surface of the conveyor belt 22. The belt cooling fan 24 blows cooling air onto the conveyor belt 22 when the temperature detected by the belt temperature sensor 25 reaches a predetermined temperature or higher.

[0020] 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 conveyed 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.

[0021] 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 to face the upper surface of the conveyor belt 22.

[0022] 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 for sucking the air containing water vapor in the drying unit 40, and a separation fan 52 for blowing separation air for separating the paper P from the conveyor belt 22. The suction fan unit 50 communicates with the space between the conveyor 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.

[0023] 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.

[0024] The conveyance belt 22 rotates counterclockwise due to the rotational drive of the drive roller 21a, so that the sheet P carried in from the sheet inlet 61 sequentially passes through the preliminary drying section 30 and the drying section 40, and is discharged outside the sheet drying apparatus 10 from the sheet outlet 62, or is carried into the second conveyance section 70.

[0025] The second conveyance section 70 is disposed below the drying section 40 and the preliminary drying section 30 with the first conveyance section 20 interposed therebetween. The second conveyance section 70 includes an inversion conveyance path 70a for inverting the front and back surfaces of the sheet P whose ink has dried, and a duplex conveyance path 70b for returning the sheet P with its front and back surfaces inverted to the image forming apparatus 100 when performing duplex printing on the sheet P.

[0026] 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.

[0027] [2. Configuration of Sheet Drying Apparatus] FIG. 3 is an enlarged view of the drying section 40 in FIG. 2. The drying section 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.

[0028] 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 FIG. 3) of heaters 43 are arranged in parallel along the conveyance direction in the heating unit 41. In the present embodiment, an infrared heater is used as the heater 43.

[0029] 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 by 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.

[0030] 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 when passing through the gaps of each reflector 44 to become hot air, and flows into the gap (drying space) between the heating unit 41 and the conveyor belt 22.

[0031] 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 the infrared rays can be maintained.

[0032] 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.

[0033] [3. Configuration of Heating Unit and Hot Air Fan] Figure 4 is a schematic diagram of the heating unit 41 and the warm air fan 42 used in the sheet drying device 10 according to the first embodiment of the present invention. In FIG. 4 and FIGS. 5, 8, and 9 described later, an example in which six heaters 43 are arranged in the heating unit 41 is shown. Also, the white arrows in the figure indicate the air flow, and the size of the white arrows indicates the magnitude of the wind speed (air volume).

[0034] In the heating unit 41 used in the sheet drying device 10 of the present embodiment, as shown in FIG. 4, one heater 43 is surrounded by one reflector 44. The air blown from the warm air fan 42 to the reflector 44 passes through the gaps between the reflectors 44 and flows into the gap (drying space) between the heating unit 41 and the conveyor belt 22.

[0035] Figure 5 is a wind speed distribution diagram below the heating unit 41 when the heating unit 41 shown in FIG. 4 is used. The wind speed distribution diagram is obtained by measuring the wind speed on the conveyor surface below the heating unit 41 with an anemometer while changing the position, and connecting the obtained measurement values with lines.

[0036] As shown in FIG. 4, by surrounding one heater 43 with one reflector 44, the number of gaps in the reflector 44 through which the air blown from the warm air fan 42 passes increases. That is, the interval between adjacent gaps becomes narrower. Therefore, warm air can be uniformly blown from the gaps of each reflector 44 into the drying space. As a result, as shown in FIG. 5, the variation in the wind speed (air volume) in the drying space becomes smaller.

[0037] Figure 6 is a schematic diagram of the heating unit 41 and the warm air fan 42 in which three heaters 43 are surrounded by one reflector 44 as a comparative example. Figure 7 is a wind speed distribution diagram below the heating unit 41 when the heating unit 41 of the comparative example shown in FIG. 6 is used.

[0038] 6, when multiple heaters 43 (three in this example) are surrounded by one reflector 44, the reflector 44 becomes larger, and the gaps between the reflectors 44 become smaller. In other words, the distance between adjacent gaps becomes wider. As a result, the hot air flowing into the drying space from the gaps between the reflectors 44 becomes uneven.

[0039] 7, there is a large variation in the air velocity (air volume) in the gap between the heating unit 41 and the conveyor belt 22. Specifically, the air velocity is strong in the gap position of the reflector 44 and weak in the center of the reflector 44. Therefore, the water vapor and steam in the center of the drying space cannot be sufficiently dispersed, and the ink drying property is reduced.

[0040] From the above results, it can be seen that the configuration of this embodiment, in which one reflector 44 surrounds one heater 43, allows warm air to flow uniformly in the drying space, efficiently removes water vapor and steam present in the drying space, and maintains the ink drying performance of the heater 43.

[0041] According to the configuration of this embodiment, the paper P transported by the transport belt 22 is heated by infrared rays emitted from the heater 43 and reflected by the reflector 44, and by hot air blown through the gaps in the reflector 44. Therefore, the ink on the paper P can be dried efficiently.

[0042] Furthermore, heater 43, which irradiates infrared rays, and reflector 44 are arranged within one heating unit 41, and hot air fan 42 is attached to heating unit 41, resulting in a compact configuration of heating unit 41. In particular, because hot air fan 42 is arranged directly above reflector 44, heating unit 41 can be made smaller in the conveyance direction and width direction, enabling space saving in drying section 40.

[0043] Furthermore, the air blown out from the warm air fan 42 hits the reflector 44, and when passing through the gaps of the reflector 44, it takes away the heat of the reflector 44. As a result, a dedicated heater for heating the air of the warm air fan 42 becomes unnecessary, the overheating of the reflector 44 can be prevented, and the safety is also improved.

[0044] FIG. 8 is a schematic diagram of the heating unit 41 and the warm air fan 42 used in the sheet drying apparatus 10 according to the second embodiment of the present invention. In the heating unit 41 used in the sheet drying apparatus 10 of the present embodiment, the intervals between the heater 43 and the reflector 44 can be individually adjusted.

[0045] In the example shown in FIG. 8, among the six sets of heaters 43 and reflectors 44, the sets of the second and third heaters 43 and reflectors 44 from both ends are moved in a direction approaching each other. As a result, portions where the intervals between adjacent reflectors 44 are wide and narrow appear alternately. And at the portions where the intervals between the reflectors 44 are wide, the wind speed (air volume) of the warm air is large, and at the portions where the intervals are narrow, the wind speed (air volume) of the warm air is small.

[0046] FIG. 9 is a block diagram showing an example of the control path of the sheet drying apparatus 10 according to the second embodiment. Here, among the control paths of the sheet drying apparatus 10, the portions necessary for the implementation of the present invention will be mainly described.

[0047] The control unit 90 includes at least a CPU (Central Processing Unit) 91 as a central arithmetic processing unit, a ROM (Read Only Memory) 92 which is a read-only storage unit, a RAM (Random Access Memory) 93 which is a readable and writable storage unit, a temporary storage unit 94 for temporarily storing data necessary for controlling each part of the sheet drying apparatus 10, and a plurality (here, two) of I / F (interfaces) 96 for transmitting control signals to each device in the sheet drying apparatus 10 and receiving input signals from the operation unit 80.

[0048] The ROM 92 stores data such as the control program for the sheet drying device 10 and numerical values necessary for control that will not be changed during the use of the sheet drying device 10. The RAM 93 stores necessary data generated during the control of the sheet drying device 10 and data temporarily required for the control of the sheet drying device 10. Also, in the RAM 93 (or ROM 92), the relationship between the printing rate of the image formed on the paper P and the arrangement of the reflector 44, which is used for the position control of the reflector 44, is also stored. The counter 95 accumulates and counts the number of sheets P loaded.

[0049] In addition, the control unit 90 transmits a control signal to each part and device in the sheet drying device 10 from the CPU 91 through the I / F 96. Also, a signal indicating its state and an input signal are transmitted from each part and device to the CPU 91 through the I / F 96. Examples of the parts and devices controlled by the control unit 90 include the first conveyance unit 20, the preliminary drying unit 30, the drying unit 40, the suction fan unit 50, the second conveyance unit 70, the operation unit 80, the reflector drive mechanism 83, etc.

[0050] Also, the printing rate data of the paper P required for the position control of the reflector 44 is input from the image forming device 100 through the I / F 96. The input printing rate data is transmitted to the temporary storage unit 94.

[0051] The voltage control circuit 84 is connected to the fan drive voltage power supply 85 and the heater voltage power supply 86, and operates these power supplies with the output signal from the control unit 90. These power supplies, according to the control signal from the voltage control circuit 84, apply a predetermined voltage to the warm air fan 42 in the heating unit 41 from the fan drive voltage power supply 85 and to the heater 43 in the heating unit 41 from the heater voltage power supply 86, respectively.

[0052] The operation unit 80 is provided with a liquid crystal display unit 81 and LEDs 82 indicating various states. The user can operate the stop / clear button of the operation unit 80 to stop the drying of the paper P, and operate the reset button to set various settings of the sheet drying device 10 to the default state. The liquid crystal display unit 81 is configured to indicate the state of the sheet drying device 10, display the drying status of the paper P, and the number of sheets of paper P carried in. Various settings of the sheet drying device 10 may also be made from the input unit 101 of the image forming apparatus 100.

[0053] The reflector drive mechanism 83 individually moves the reflectors 44 in the heating unit 41 in the transport direction. The reflector drive mechanism 83 is composed of, for example, a motor and a rack & pinion mechanism.

[0054] In the present embodiment, based on the printing rate (the ratio of the ink adhesion area to the surface area) of the paper P transmitted from the image forming apparatus 100, the intervals between the reflectors 44 are automatically adjusted. For example, when the printing rate of the paper P carried into the sheet drying device 10 is high, since the amount of ink adhering to the paper P is large, it is necessary to improve the heating efficiency of the paper P by the heating unit 41 and improve the drying performance in the drying unit 40. Therefore, the control unit 90 adjusts the gaps between the reflectors 44 using the respective reflector drive mechanisms 83 based on the printing rate data transmitted from the image forming apparatus 100.

[0055] Specifically, when the printing rate of the paper P is high, when the paper P is sufficiently heated by the heating unit 41, that is, when a large amount of water vapor is generated when the upstream side in the transport direction of the paper P passes through the drying unit 40. In this case, in order to increase the heating efficiency of the paper P, it is conceivable to widen the intervals between the three reflectors 44 on the upstream side in the transport direction among the six reflectors 44 in the heating unit 41 and increase the amount of warm air blown to the upstream side in the transport direction of the paper P.

[0056] Alternatively, when it is desired to quickly disperse the water vapor generated from the paper P, it is conceivable to narrow the intervals between the three reflectors 44 on the upstream side in the conveyance direction and increase the wind speed of the warm air blown onto the upstream side in the conveyance direction of the paper P. The intervals between the reflectors 44 can be arbitrarily changed according to the ink amount on the paper P, the amount of generated water vapor, etc.

[0057] As in this embodiment, by adopting a configuration in which the gap between the reflectors 44 can be automatically adjusted based on the printing rate of the paper P, the air volume and wind speed of the warm air flowing into the drying space can be adjusted to a state suitable for the actual ink adhesion amount and water vapor generation. Therefore, the heating efficiency by the heating unit 41 and the diffusion efficiency of water vapor can be enhanced, and more uniform ink dryness can be obtained.

[0058] FIG. 10 is a schematic diagram of the heating unit 41 and the warm air fan 42 used in the sheet drying device 10 according to the third embodiment of the present invention. In the heating unit 41 used in the sheet drying device 10 of this embodiment, the inclination of the reflector 44 can be individually adjusted. The control path of the sheet drying device 10 is the same as that of the second embodiment shown in FIG. 9, but the reflector drive mechanism 83 varies the inclination of the reflector 44.

[0059] In the example shown in FIG. 10, all six reflectors 44 are inclined so that the lower ends face the downstream side in the conveyance direction (the left side in FIG. 10). As shown in FIG. 10, by inclining the lower end of the reflector 44 to the downstream side in the conveyance direction, the warm air passing through the gap between the reflectors 44 flows in one direction (from the upstream side to the downstream side in the conveyance direction) in the drying space.

[0060] Also in this embodiment, based on the printing rate of the sheet P transmitted from the image forming apparatus 100, the inclination of each reflector 44 is automatically adjusted. For example, when the printing rate of the sheet P carried into the sheet drying apparatus 10 is high, since the amount of ink adhering to the sheet P is large, the amount of water vapor generated from the sheet P also increases. Therefore, the control unit 90 adjusts the inclination of each reflector 44 using each reflector driving mechanism 83 based on the printing rate data transmitted from the image forming apparatus 100.

[0061] Specifically, when the printing rate of the sheet P is high, a large amount of water vapor is generated when the sheet P passes through the drying unit 40. In this case, the lower ends of the six reflectors 44 in the heating unit 41 are all tilted so as to face the downstream side in the conveyance direction, and the warm air blown onto the sheet P is caused to flow in one direction (the downstream side in the conveyance direction). Thereby, the water vapor and steam present in the drying space can be dispersed in one direction (the downstream side in the conveyance direction), and the diffusion efficiency of the water vapor and steam can be increased.

[0062] By adopting a configuration in which the inclination of the reflector 44 can be automatically adjusted based on the printing rate of the sheet P as in this embodiment, the direction of the warm air flowing through the drying space can be adjusted to a state suitable for the actual amount of water vapor generated. Therefore, more uniform ink drying properties can be obtained.

[0063] Also, as shown in FIG. 10, by tilting the lower end portion of the reflector 44 so as to face the downstream side in the conveyance direction, the blowing of warm air to the upstream side of the drying space can be suppressed. Therefore, it is possible to prevent the sheet P from floating due to the blowing of warm air to the leading end of the sheet P.

[0064] FIG. 11 is a side cross-sectional view of the heating unit 41 used in the sheet drying apparatus 10 according to the fourth embodiment of the present invention, cut along the width direction. FIG. 12 is an enlarged view of one end side in the width direction (the right end side in FIG. 11) of the heating unit 41 in FIG. 11. FIG. 13 is a cross-sectional perspective view of the heating unit 41 used in the sheet drying apparatus 10 according to the fourth embodiment, cut along the width direction. FIG. 14 is an enlarged view of the other end side in the width direction (the left end side in FIG. 13) of the heating unit 41 in FIG. 13.

[0065] In this embodiment, auxiliary reflectors 45 are arranged at both longitudinal ends of the reflector 44 extending along the width direction. The configurations of other parts of the heating unit 41, such as the arrangement and configuration of the reflector 44, are the same as those in the first to third embodiments.

[0066] As shown in FIG. 11, a pair of auxiliary reflectors 45 are arranged to face each other in the width direction, and their inner surfaces serve as reflecting surfaces. The auxiliary reflector 45 is composed of an upper reflector 45a and a lower reflector 45b. As shown in FIG. 12, the upper end portion of the upper reflector 45 overlaps the reflector 44. The lower end portion of the lower reflector 45b faces the conveyor belt 22 with a predetermined interval therebetween.

[0067] As shown in FIG. 13, the auxiliary reflector 45 extends along the conveyance direction so as to overlap the entire region where the reflectors 44 (heaters 43) are arranged in parallel. As shown in FIG. 14, an arc-shaped notch 46 for avoiding interference with the heater 43 is formed in the lower reflector 45b at the portion facing the upper reflector 45a.

[0068] By arranging the auxiliary reflector 45 at the end of the heater 43, it is possible to prevent the warm air flowing into the drying space from the upper side from flowing out to the outside in the axial direction of the heater 43. Also, at both axial ends of the heater 43, the irradiation intensity of infrared rays decreases compared to the central portion, but since the infrared rays emitted from both ends of the heater 43 are reflected inward by the auxiliary reflector 45, it is possible to suppress the decrease in the irradiation intensity (radiant heat) of infrared rays at both ends of the heater 43, and more uniform ink drying properties can be obtained.

[0069] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the second and third embodiments described above, the interval and inclination of the reflector 44 were automatically adjusted based on the printing rate, but the interval and inclination of the reflector 44 may be manually adjusted.

[0070] In addition, 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

[0071] The present invention can be used for 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, even if the drying area becomes long, the air volume in the drying area can be maintained uniformly, and it is possible to provide a sheet drying device capable of equalizing the drying property and suppressing drying unevenness, and an image forming system including the same.

Explanation of Reference Numerals

[0072] 10 Sheet drying device 20 Conveying unit 30 Pre-drying unit 40 Drying unit 41 Heating unit 42 Warm air fan 43 Heater (infrared heater) 44 Reflector 45 Auxiliary reflector 45a Upper reflector 45b Lower reflector 50 Suction fan unit 51 Separation fan 52 Suction fan 53 First duct 54 Second duct 60 Exhaust port 61 Sheet inlet 62 Sheet outlet 83 Reflector drive mechanism 90 Control unit 100 Image forming apparatus 200 Image forming system P Paper (sheet)

Claims

1. A conveying unit that conveys a sheet on which an image is formed with 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: The drying unit is: A plurality of infrared heaters that extend in a width direction that is horizontally orthogonal to the conveying direction of the sheet and are arranged in parallel along the conveying direction, A plurality of reflectors that surround the infrared heaters from the direction opposite to the conveying unit, A heating unit having the above, 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: A sheet drying device, wherein a plurality of the reflectors are arranged in the same number as the infrared heaters so as to individually surround each of the infrared heaters one by one.

2. The sheet drying device according to claim 1, characterized in that the distance between adjacent reflectors can be individually adjusted.

3. A reflector driving mechanism that moves the reflector in the conveying direction, A control unit that controls the reflector driving mechanism, Comprising: The sheet drying device according to claim 2, characterized in that the control unit adjusts the distance between adjacent reflectors based on the printing rate of the sheet conveyed by the conveying unit.

4. When the printing rate of the sheet conveyed by the conveying unit is equal to or higher than a predetermined value, the control unit widens the distance between the reflectors arranged on the upstream side in the conveying direction compared to the reflectors arranged on the downstream side, thereby increasing the air volume of the hot air on the upstream side in the conveying direction. The sheet drying device according to claim 3, characterized by this.

5. When the printing rate of the sheet conveyed by the conveying unit is equal to or higher than a predetermined value, the control unit narrows the distance between the reflectors arranged on the upstream side in the conveying direction compared to the reflectors arranged on the downstream side, thereby increasing the wind speed of the hot air on the upstream side in the conveying direction. The sheet drying device according to claim 3, characterized by this.

6. The sheet drying device according to claim 1, characterized in that the inclination of the conveying direction when the reflector is viewed from the width direction can be adjusted to the same inclination for all of the plurality of reflectors.

7. a reflector drive mechanism that swings the lower end of the reflector in the conveying direction; a control unit that controls the reflector drive mechanism; comprising; The control unit adjusts the inclination of the reflector in the conveying direction based on the printing rate of the sheet conveyed by the conveying unit. The sheet drying device according to claim 6, characterized in that.

8. When the printing rate of the sheet conveyed by the conveying unit is equal to or higher than a predetermined value, the control unit adjusts the inclination of the reflector in the conveying direction so that the lower end of the reflector faces the downstream side in the conveying direction. The sheet drying device according to claim 7, characterized in that.

9. A pair of auxiliary reflectors facing each other in the width direction are arranged at both ends of the reflector in the width direction. The sheet drying device according to claim 1, characterized in that.

10. The auxiliary reflector extends in the conveying direction so as to overlap a region where a plurality of the reflectors are arranged in parallel. The sheet drying device according to claim 9, characterized in that.

11. An image forming apparatus that forms an image using ink containing moisture on a sheet; The sheet drying device according to any one of claims 1 to 10, which dries the sheet on which an image is formed by the image forming apparatus; An image forming system comprising.

Images