Recording medium drying device and image formation device including the same

Abstract

To solve such the problem that, when air leakage occurs in a part where ducts are fitted, an air volume and an air velocity to be blown decrease and a water content cannot be dried sufficiently from the ink.SOLUTION: A duct is split vertically relative to an opening part that continues in parallel with a transportation direction. Simplifying a split form of the duct improves sealability of the split part to prevent air leakage.SELECTED DRAWING: Figure 8(b)

Description

[Technical field]

[0001] The present invention relates to a drying device for drying a recording medium such as paper, and also to an ink-jet recording method equipped with the drying device. [Background technology]

[0002] Some inkjet recording systems are equipped with a drying device that evaporates the moisture in the ink and dries the recording medium. Many drying devices accelerate the drying of the recording medium by blowing hot air onto the recording medium on which the ink is placed. However, as the speed of image forming devices increases, if the wind speed of the air blown is increased to dry the recording medium quickly, the air blown onto the recording medium will lift the paper, which is the recording medium, during transportation. This can cause problems such as delays in the transportation of the paper and jams due to bent corners.

[0003] Therefore, Patent Document 1 proposes a drying device to avoid this problem. In this drying device, the recording medium is sucked and conveyed by a suction conveying belt equipped with a plurality of holes, while the drying device blows air from above toward one side of the recording medium to dry it. The drying device is configured to reduce the amount of airflow from the center to both ends of the recording medium in the recording medium width direction perpendicular to the recording medium conveying direction. This makes it possible to push out the air that has entered between the recording medium and the suction conveying belt from the center to both ends in the width direction. As a result, the recording medium is easily brought into close contact with the suction conveying belt, preventing the recording medium from floating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5476330 specification Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional configuration has the following problems.

[0006] The issue is air leakage from places other than the blowing port of the ventilation duct, and since the ventilation duct has a hollow shape to blow air, it is made up of divided ducts joined together. If air leakage occurs from the joined ducts, the volume and speed of the air blown will decrease, and it is expected that the moisture in the ink will not be able to be dried sufficiently.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus in which the division of the air blower duct is simplified in shape, thereby improving the sealing performance of the division and preventing air leakage. [Means for solving the problem]

[0008] In order to achieve the above object, the image forming apparatus according to claim 1 has the following configuration: a paper transport path for transporting a recording medium, a duct 45 arranged opposite the paper transport path and equipped with a plurality of blowing ports 10 for blowing air onto the recording medium, a ventilation duct 14 upstream of the duct, a blowing means 13 for sucking air into the ventilation duct, and a heater 15 for heating the air to be blown onto the recording medium, the duct has a plurality of openings between the plurality of blowing ports that penetrate from a surface facing the paper transport path to an opposite surface, the duct is divided perpendicular to the continuous openings parallel to the transport direction and perpendicular to the paper transport direction, and is sealed at the dividing portions. Effect of the Invention

[0009] According to the present invention, by dividing the air duct into a simple shape, it is possible to improve the sealing performance of the divided portion and prevent air leakage. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Diagram 2] FIG. 2 is a configuration diagram of a system relating to a drying function unit. [Diagram 3] FIG. 2 is a configuration diagram of a drying function section in the drying module. [Figure 4] FIG. 4 is a side cross-sectional view of a hot air blowing unit and a drying belt. [Diagram 5] FIG. 4 is a diagram showing the configuration of a cold air blowing unit. [Figure 6(a)] FIG. 4 is a detailed view of the hot air blowing nozzle on the bottom surface of the duct. [Figure 6(b)] FIG. 13 is a detailed view illustrating the shape between multiple ducts. [Figure 7] FIG. 2 is a perspective view of the vicinity of the hot air blowing nozzle of the air duct. [Figure 8(a)] FIG. [Figure 8(b)] FIG. [Figure 9] 13 is a table showing experimental results regarding sheet floating. [Figure 10] FIG. 4 is a schematic diagram relating to the arrangement of a transport detection sensor. [Figure 11] FIG. 1 is a schematic diagram of the problem that the present invention is trying to solve. [Figure 12(a)] FIG. 4 is a partial perspective view showing a cold air blowing nozzle on the bottom surface of the duct. [Figure 12(b)] 4 is a schematic diagram illustrating an arrangement of a transport detection sensor and a flat portion. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below with reference to preferred embodiments. Note that the embodiments described below are preferred embodiments of the present invention, and therefore various technically preferable limitations are attached, but the scope of the present invention is not unduly limited by the following explanation, and all of the configurations described in the present embodiments are not essential constituent elements of the present invention.

[0012] (Image forming device) An inkjet recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0013] 1 is a schematic diagram showing an example of the schematic configuration of an inkjet recording apparatus. This inkjet recording apparatus is a sheet-fed inkjet recording apparatus that produces a recorded matter by forming an ink image on a sheet S using two liquids, a reaction liquid and an ink.

[0014] The inkjet recording device of this embodiment is composed of a paper feeding module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inversion module 6000, and a paper output stacking module 7000. A cut-paper-like sheet S supplied from the paper feeding module 1000 is transported along a transport path, processed in each module, and discharged to the paper output stacking module 7000.

[0015] The paper feed module 1000 is provided with three storage containers 1100a-c for storing sheets S, which can be pulled out to the front side of the device. The sheets S are fed one by one in each of the storage containers 1100a-c by a separation belt and a transport roller, and transported to the print module 2000. The number of storage containers 1100a-c is not limited to three, and the configuration may include one, two, or four or more.

[0016] The print module 2000 has a pre-imaging registration correction section (not shown), a print belt unit 2200, and a recording section 2300. The sheet S transported from the paper feed module 1000 has its inclination and position corrected by the pre-imaging registration correction section, and is then transported to the print belt unit 2200. The recording section 2300 is disposed at a position facing the print belt unit 2200 on the transport path. The recording section 2300 is a sheet processing section that performs recording processing (printing) on ​​the transported sheet S from above with a recording head to form an image. The sheet S is attracted and transported by the print belt unit 2200, ensuring clearance with the recording head.

[0017] In addition, a plurality of recording heads are arranged along the conveying direction. In this example, in addition to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), a total of five line-type recording heads corresponding to the reaction liquids are provided. The number of colors and the number of recording heads are not limited to five. The inkjet method can employ a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, and the like. Ink of each color is supplied to the recording head from an ink tank (not shown) through an ink tube. The sheet S printed by the recording unit 2300 is conveyed by the print belt unit 2200, and the misalignment and color density of the image formed on the sheet S can be detected and the printed image can be corrected by an in-line scanner (not shown) arranged downstream of the recording unit in the conveying direction.

[0018] The drying module 3000 has a decoupling belt unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400, and is a unit that reduces the liquid content contained in the ink applied onto the sheet S by the recording unit 2300 and improves the fixation of the ink to the sheet S. The sheet S printed by the recording unit 2300 of the print module 2000 is transported to the decoupling unit 3200 arranged in the drying module 3000. The decoupling unit 3200 can transport the sheet S from above by air pressure and belt friction, and by weakly holding and transporting the sheet S on the belt, it prevents the sheet S from shifting on the print belt unit 2200 on which the ink image is formed.

[0019] The sheet S conveyed from the decoupling section 3200 is adsorbed and conveyed by the drying belt unit 3300, and at the same time, hot air is blown from a hot air blowing section 3400 arranged above the belt to dry the ink-applied surface of the sheet S. Note that the drying method may be a combination of a method of applying hot air, a method of irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.), and a conductive heat transfer method by contact with a heating element.

[0020] The fixing module 4000 has a fixing belt unit 4100, and can fix the ink onto the sheet S by passing the sheet S conveyed from the drying module 3000 between a heated upper belt unit and a lower belt unit.

[0021] The cooling module 5000 has a plurality of cooling sections 5100, and cools the high-temperature sheet S transported from the fixing module 4000. The cooling section 5100 is configured to take in outside air into a cooling box with a fan to increase the pressure inside the cooling box, and cool the sheet S by blowing air from nozzles formed in a transport guide onto the sheet S. The cooling sections 5100 are arranged on both sides of the transport path, and can cool the sheet S from both sides. The cooling module 5000 also has a transport path switching section, and can switch the transport path of the sheet S depending on whether the sheet S is transported to the inversion module 6000 or to a double-sided transport path used for double-sided printing. During double-sided printing, the sheet S is transported to a transport path below the cooling module 5000, then further transported along a double-sided transport path through the fixing module 4000, drying module 3000, print module 2000, and paper feed module 1000, and then transported again to the pre-imaging registration correction unit of the print module 2000, the print belt unit 2200, and the recording unit 2300, where it is printed. The double-sided transport unit of the fixing module 4000 has an inversion unit 1 (4200) that inverts the sheet S from front to back.

[0022] The reversing module 6000 has a reversing section 2 (6400) and can reverse the front and back of the sheet S being conveyed, and can freely change the front and back orientation of the sheet S to be discharged.

[0023] The discharge stacking module 7000 has a top tray 7200 and a stacking section 7500, and aligns and stacks the sheets S conveyed from the reversing module 6000.

[0024] The above is an outline of the inkjet recording apparatus according to the present invention.

[0025] Example 1 <Drying function section> Next, the drying function section 3010 of the drying module 3000 according to the present invention will be described in detail.

[0026] As described above, the upper part of the drying module 3000 is the drying function section 3010, which receives the sheet S discharged from the print module 2000, dries it, and then serves as the linear paper transport path 1 for delivering the sheet S to the fixing module 4000. The upstream and downstream sections of this paper transport path 1 have different functions.

[0027] The upstream part of the drying function part has a decoupling part 3200 composed of a decoupling belt 2 and a cold air blowing unit 3, and the paper S is pressed against the decoupling belt 2 and transported by blowing cold air from the vertically upper side of the decoupling belt 2. The decoupling belt unit 2 is provided with a plurality of holes for passing the air blown from the cold air blowing unit 3 from the blowing surface to the belt opposing side. When the leading edge of the sheet S reaches the decoupling belt 2 of the drying module 3000, the trailing edge side of the sheet S is still on the print belt 4 of the print module 2000. On the print belt 4, printing is being performed on the sheet S, and for this reason, the sheet S is suction-transported on the print belt 4. In order not to disturb this printing process, the force pressing the paper S against the decoupling belt 2 is weaker than the suction force of the print belt, and the decoupling belt 2 is driven at a speed slightly faster than the print belt 4. In other words, the sheet S is configured to always slide against the decoupling belt 2 while the trailing edge side of the sheet S is on the print belt 4.

[0028] On the other hand, the moment the rear end of the sheet S leaves the area of ​​the print belt 4, the transport of the sheet S becomes dependent on the decoupling belt 2. At this time, it is necessary to control the blowing force of the cold air blowing unit 3 so that the paper does not slip due to the resistance to transport. Therefore, the air speed from the cold air blowing unit 3 is controlled to a predetermined pressure using a pressure sensor installed inside the unit and an intake fan installed in the intake section, and a blowing force is applied to the sheet S. The cold air blowing unit 3 has a blowing nozzle surface with many blowing nozzle holes 5 for passing air so that a uniform pressing force can be applied to the sheet S.

[0029] The downstream of the drying function section 3010 has a drying section 6 composed of a drying belt unit 3300 and a hot air blowing unit 8, and the drying belt unit 3300 sucks the paper and fixes it on the belt while blowing hot air from above vertically to dry the paper S, and transports the paper while suppressing waviness called cockling. In order to quickly dry the paper S, the surface temperature of the drying belt 7 is controlled to a predetermined temperature via a temperature sensor provided inside the drying belt unit 3300 and a heater roller 9 having a halogen heater inside, and the sheet S is heated. The hot air temperature in the hot air blowing unit is controlled to a predetermined temperature using a temperature sensor and a sheathed heater provided inside the unit, and the wind speed from the hot air blowing nozzle 10 is controlled to a predetermined pressure using a pressure sensor provided inside the unit and a blower fan 13 provided in the intake section, drying the ink on the sheet S.

[0030] The hot air blowing unit 8 has a hot air blowing surface 12 provided with many hot air blowing nozzles 10 for passing air so that the sheet S can be dried evenly. In order to fix the paper S on the drying belt 7, the suction pressure on the upper surface of the drying belt 7 is controlled to a predetermined pressure using a pressure sensor provided inside the suction box and an exhaust fan provided in the exhaust section, and the sheet S is fixed on the belt. The drying belt 7 has many suction holes 11 to suck the sheet S evenly. The distance from the suction end position of the print belt to the suction start position of the drying belt is set to be longer than the maximum sheet length.

[0031] <Hot air blowing unit> The configuration of the hot air blowing unit 8 in this embodiment will be described with reference to FIG.

[0032] As shown in FIG. 4, the hot air blowing unit 8 is composed of a blower fan 13, a blower duct 14, a heater 15, a temperature sensor 16, and an intake duct 17.

[0033] The blower fan 13 is an axial flow fan, but may be another blower source such as a sirocco fan. The heater 15 is a sheath heater, but may be another heat source such as a Kanthal heater. The intake duct 17 is connected to the intake side of the intake fan 13. The blower duct 14 has a heater 15 and a temperature sensor 16 inside, and the blower side of the blower fan 13 is connected to the end of the blower duct 14. The heater 15 is disposed on the downstream side of the blower fan 13. The surface facing the sheet further downstream of the heater 15 is the hot air blowing surface 12, and multiple hot air blowing nozzles 10 are provided. As shown in FIG. 6(a), the multiple hot air blowing nozzles 10 are cylindrical, and the nozzles in the conveying direction are connected to each other by ribs 30 that are the same height as the cylinders. The hot air blowing nozzles 10 are arranged at equal intervals in the sheet conveying direction A and in the sheet width direction B perpendicular to the conveying direction so that the density of holes per unit area is uniform. Specifically, the cylindrical shape is 5 mm high, the hole diameter is 2 mm, the interval between holes in the conveying direction A is 14 mm, and the interval between holes in the sheet width direction B is 14 mm.

[0034] The rows of holes in the width direction B of the sheet are shifted 7 mm from each other in the conveying direction A on the left and right. The distance G between the blowing surface 12 of the hot air blowing nozzle 10 and the drying belt 7 is 10 mm, and the distance H between the hot air blowing surface 12 and the drying belt 7 is 15 mm. The wind speed at the width nozzle outlet is about 33 m / s, and the sheet conveying speed is 700 mm / s. With respect to the sheet conveying direction B, an area wider than the maximum size width of the sheet is provided so that air can be blown to an area wider than the maximum size of the sheet. Between the hot air blowing nozzles 10 and 10, there are a plurality of openings 18 that are continuous in parallel with the conveying direction and penetrate in the direction C perpendicular to the sheet. The wall surface of the opening 18 is a surface 31 inclined with respect to the sheet surface, and the width of the opening becomes wider as it moves away from the sheet in the direction perpendicular to the sheet. The temperature sensor 16 is disposed on the upper surface inside the duct facing the hot air blowing nozzle 10. The current for generating heat from the heater 15 is controlled in accordance with the temperature of the temperature sensor 16 .

[0035] As shown in FIG. 4, when the blower fan 13 is driven, air in the drying section 6 is sucked into the blower fan 13 through the intake duct 17 and reaches the heater 15 inside the blower duct 14. The air heated by the heater 15 passes through the hot air blowing nozzle 10 and is blown onto the sheet. As shown in FIG. 7, the air blown onto the sheet passes through the space between the hot air blowing surface and the drying belt 7 in the sheet conveying direction A, the sheet width direction B perpendicular to the conveying direction, the opening 18 of the blower duct 14 in the sheet vertical direction C, and the suction hole 11 of the drying belt 7 that is not blocked by the sheet. A part of the air is exhausted from inside the drying section 6 to the outside of the machine through the exhaust duct (not shown), and the rest is sucked into the blower fan 13 through the intake duct 17 and circulated inside the drying section 6. When the absolute moisture content in the drying section 6 increases due to the evaporation of ink, it becomes difficult to dry the sheet, so the air is exhausted to the outside of the machine, while a part of the hot air is circulated and reused, thereby reducing power consumption.

[0036] <Hot air blowing nozzle, opening> The hot air blowing nozzle 10 and the opening 18 in this embodiment will be described in detail.

[0037] The relationship between the amount of air coming out of the hot air blowing nozzle and the speed of air passing through between the sheet and the hot air blowing surface will be explained. When there is no opening as shown in Fig. 7, the hot air blown to the sheet passes through cross section 40 in the conveying direction and cross section 41 in the conveying width direction between the sheet and the hot air blowing surface.

[0038] If the total air volume from the hot air blowing nozzle 10 is Q, and the sum T of the area of ​​the cross section 40 in the conveying direction and the area of ​​the cross section 41 in the conveying width direction is Q, the average air speed V in the conveying direction and the conveying width direction is V=Q / T. Therefore, when the air volume Q is constant, the average air speed V decreases as the sum T of the area of ​​the cross section 40 in the conveying direction and the cross section 41 in the conveying width direction increases. In other words, in FIG. 4, the greater the distance H between the hot air blowing surface 12 and the sheet, the more the air speed flowing to the sheet can be suppressed and the paper lifting can be suppressed. On the other hand, in FIG. 4, the closer the distance G between the tip of the hot air blowing nozzle 10 and the sheet, the easier it is to dry the sheet. For this reason, in this embodiment, as shown in FIG. 4, a step of 5 mm is provided between the tip of the hot air blowing nozzle 10 and the hot air blowing surface 12. Furthermore, by connecting the hot air blowing nozzle 10 with a rib 30 in the conveying width direction, the hot air can be easily discharged in the conveying width direction.

[0039] 7, when there is an opening, the hot air blown to the sheet passes through cross section 42 in the conveying direction and cross section 43 in the conveying width direction between the sheet and the hot air blowing surface 12, and also passes vertically through surface 44 of the opening. Also, the wall surface of the opening 18 is provided with surface 31 inclined relative to the sheet surface, thereby reducing the flow path resistance.

[0040] If the total air volume coming out of the hot air blowing nozzle 10 is Q, the sum of the cross-sectional areas in the conveying direction and the conveying width direction is T, and the sum of the cross-sectional areas of the openings perpendicular to the sheet is U, then the average air speed V' in the conveying direction and the conveying width direction is V'=Q / (T+U). Therefore, V=Q / T>V'=Q / (T+U), that is, the average air speed V when there is no opening > the average air speed V' when there is an opening. Therefore, the hot air blowing unit 8 of this embodiment can suppress the lifting of the sheet due to the air blowing because the air speed is lower than when there is no opening.

[0041] Further, as shown in FIG. 4, the hot air blowing nozzle 10 of this embodiment is arranged at equal intervals in the sheet conveying direction and in the sheet width direction perpendicular to the conveying direction so that the density of holes per unit area is uniform. For this reason, air can be blown uniformly at the center and both ends of the sheet. Therefore, compared with the case where the air volume is reduced at both ends rather than at the center of the conveying width as in the conventional example, air can be blown uniformly onto the sheet, and uneven drying can be reduced.

[0042] Also, assuming that the wind speed of the hot air blowing nozzle is v and the total area of the holes of the hot air blowing nozzle is Z, then v = Q / Z. Therefore, substituting into V' = Q / (T + U), we get V' = Z / (T + U)v. Here, substituting U = Z, we get V' = (1 - T / (T + Z))v. Since 1 - T / (T + Z) < 1, we can derive that V' < v. In this way, if the total area U of the openings is made equal to or greater than the total area Z of the holes of the hot air blowing nozzle, the wind speed flowing onto the sheet can surely be made smaller than the wind speed of the hot air blowing nozzle. Therefore, it is desirable that the total area U of the openings be equal to or greater than the total area Z of the holes of the hot air blowing nozzle.

[0043] Also, even when the opening 18 is provided perpendicular to the conveying direction, the amount of air flowing in the sheet conveying direction A can be reduced. However, since the air flowing into the opening 18 tends to flow in the conveying direction because it escapes above the sheet, there is a possibility of causing the sheet to float. For this reason, it is better to provide the opening 18 parallel to the conveying direction.

[0044] <Cold air blowing unit> The configuration of the cold air blowing unit 3 in this embodiment will be described with reference to FIG. 5. The cold air blowing unit 3 is arranged upstream with respect to the hot air blowing unit 8 and is arranged opposite to the decoupling belt 2 downstream of the print belt unit 2200.

[0045] As shown in Fig. 5, the cold air blowing unit 3 is composed of a blower fan 23, a blower duct 24, an intake duct 27, and a cold air blowing nozzle 5. The blower fan 23 is an axial fan, but other blowing sources such as a sirocco fan may also be used. The intake duct 27 is disposed on the intake side of the blower fan 23. In addition, an end of the intake duct 27 is connected to the exterior surface of the main body, and air can be taken in through an intake hole 28 provided on the exterior surface of the main body. As a result, when the blower fan 23 is operated, fresh air outside the device is taken in by the blower fan 23.

[0046] Moreover, the blower duct 24 is disposed on the exhaust side of the blower fan 23. Moreover, at the outlet of the blower duct 24, the surface facing the sheet is a cold air blowing surface 25, and a cold air blowing nozzle 5 is provided. The airflow generated by the blower fan 23 is blown through the cold air blowing nozzle 5 to the passing sheet S. Opposite the cold air blowing nozzle 5 is provided the above-mentioned decoupling belt unit 3200. The sheet S is pressed against the decoupling belt unit 3200 by the wind pressure of the airflow coming out of the cold air blowing nozzle 5.

[0047] As described above, the cold air blowing unit 3 draws in air from outside the device body. Unlike the hot air blowing unit 8, it can blow air at the same temperature as the outside air temperature (lower than the hot air blowing unit 8) onto the sheet S. Although it depends on the outside air temperature, in this configuration, the airflow blown from the cold air blowing unit 3 has a wind speed of 30 to 40 m / s and a temperature of 20 to 40°C.

[0048] <Distance between the hot air blowing nozzle and the cold air blowing nozzle conveying part> The relationship between the hot air blowing unit and the distance between the blowing nozzle of the cold air blowing unit and the transport section in this embodiment will be described.

[0049] The distance G between the blowing surface 12 of the hot air blowing nozzle 10 of the hot air blowing unit and the drying belt 7 is 10 mm, and the distance G between the blowing surface 12 of the blowing nozzle 10 of the cold air blowing unit and the decoupling belt 2 is 15 mm, and the distance between the hot air blowing nozzle 10 of the hot air blowing unit and the drying belt 7 is made closer to the distance between the blowing nozzle 10 of the cold air blowing unit and the decoupling belt 2. This is because it is considered that the sheet S discharged from the print module 2000 may curl, and the distance G between the blowing nozzle 10 of the cold air blowing unit and the decoupling belt 2, which is disposed immediately downstream of the print module 2000, is set to a distance that does not collide with the blowing nozzle even if the sheet curls, taking into consideration the curl of the sheet. Also, the closer the distance G between the hot air blowing nozzle of the hot air blowing unit disposed downstream of the cold air blowing unit and the sheet, the easier it is to dry the sheet, so the hot air blowing nozzle is made closer to the sheet. This is because the paper is fixed onto the belt while being transported by sucking it with the drying belt unit 3300 arranged opposite the hot air blowing unit, making the sheet less susceptible to curling and allowing the hot air blowing nozzle to be positioned closer to the sheet.

[0050] <Configuration of inlet and spray nozzle> The configuration of the inlet 46 of the duct 45 and the hot air blowing nozzle 10 in this embodiment will be described. In the hot air blowing unit, the intake duct 17 is connected to the intake side of the intake fan 13, the end of the blower duct 14 is connected to the exhaust side of the intake fan 13, and the duct 45 equipped with multiple hot air blowing nozzles 10 is connected to the downstream side of the blower duct. The size of the hole of the inlet 46 of the duct 45 is 60 mm x 42 mm, and the hot air blowing nozzle 10 is 5 mm high and 2 mm in diameter on the cylindrical shape. The wind speed from the hot air blowing nozzle 10 is controlled to a predetermined pressure using a pressure sensor installed inside the unit and the blower fan 13 installed in the intake section, and the wind speed at the outlet of the hot air blowing nozzle is about 33 m / s. In addition, due to the relationship between the inlet 46 of this duct 45 and the hot air blowing nozzles, the pressure inside the duct 45 is made uniform and the wind speed at the outlets of the multiple hot air blowing nozzles can be made uniform, so that air can be blown uniformly onto the sheet and uneven drying can be reduced.

[0051] <Problems to be Solved by the Present Invention> As described above, in this embodiment, the opening 18 is provided between the hot air blowing nozzles 10 provided in the air blowing duct 14. In this case, since the air blowing duct has a hollow shape to blow air, it is configured by joining divided ducts and the opening has a complex shape, so air leakage may occur from the part where the ducts are joined at a complex shape. If air leakage occurs from the part where the ducts are joined, it is expected that the amount and speed of the blown air will decrease and the moisture in the ink will not be able to be sufficiently dried.

[0052] <Effects of the present invention> Therefore, in this configuration, as shown in Fig. 8(b), duct 45 is divided into duct right 47 and duct left 48 perpendicular to the continuous opening parallel to the transport direction and perpendicular to the paper transport direction. This allows the duct to be divided into a simple shape that avoids the complex shape of the opening, and the divided part of the simple shape can be sealed. This makes it possible to prevent air leakage from the joint of the ducts, and makes it possible to sufficiently dry the moisture in the ink without reducing the volume and speed of the blown air.

[0053] Example 2 In this embodiment 2, the positional relationship between the cold air blowing nozzle 5, the hot air blowing nozzle 10, and the transport detection sensor 40 described later in the embodiment 1 will be described in detail. Note that the configuration other than the following additional configuration is the same as that of the embodiment 1, and the following description will be focused on the contents of the embodiment 2.

[0054] <Nozzle hole pitch settings for cold air blowing nozzle 5 and hot air blowing nozzle 10> Hereinafter, a detailed explanation will be given of the hole pitch of the nozzle holes in the above-mentioned cold air blowing nozzle 5 and hot air blowing nozzle 10 in this embodiment. In this embodiment, each nozzle adopts the same shape and configuration, and in the following explanation, the hot air blowing nozzle 10 will be described as an example.

[0055] Fig. 6(b) is a simplified diagram showing the arrangement of nozzle holes of the multiple hot air blowing nozzles 10 shown in Fig. 6(a), and as shown in the figure, the rows of holes in the width direction B of the sheet are arranged with a pitch p offset from each other on the left and right in the conveying direction A, and the interval of the nozzle hole pitch p in the sheet conveying direction A is set to "5 mm to 10 mm." This allows the sheet S to be stably pressed against the belt from above, suppressing the floating of the sheet S due to the influence of the wind blown and reflected by the drying belt 7 or preceding paper where there is no sheet S.

[0056] The above-mentioned nozzle hole pitch p is set based on the following considerations.

[0057] In this embodiment, an experiment was conducted to confirm whether the paper rose when hot air was blown from the hot air blowing unit 8 while varying the value of the nozzle hole pitch p. The results are shown in FIG.

[0058] The experimental conditions are as follows: Wind speed: 33m / s Seat: GFC-081 Curl height: 10 mm (height at which the leading edge of the transported paper curls up)

[0059] Looking at the experimental results in Figure 9, it can be said that the pitch p between the nozzle holes in the sheet transport direction A (see Figure 6(b)) is preferably 10 mm or less. The smaller this value, the more advantageous it is in terms of addressing the issue of the sheet floating. On the other hand, if p is made smaller, the number of hot air blowing nozzles 10 in the duct increases, which increases the total opening area of ​​the duct and causes a problem of reduced air speed for the same air volume. If the air speed is low, the force pressing down on the sheet becomes weaker, making the sheet transport unstable, and when targeting the drying section of an inkjet printer as in this embodiment, the drying capacity decreases. For this reason, it is preferable that the hole pitch be 5 mm or more.

[0060] <Transport detection sensor 40> In the paper transport path 1 provided in the drying module 3000, a transport detection sensor 40 is provided to check the sheet S transported from upstream to downstream. In this embodiment, a reflective photosensor is used as the transport detection sensor 40, but the transport detection sensor 40 is not limited to this and may be a prism photosensor or an actuator type photosensor. This will be described separately in the modified example described later.

[0061] Here, the arrangement of the transport detection sensor 40 will be described. In this embodiment, as shown in FIG. 10, the transport detection sensor 40 is arranged in a guide unit 41 that is provided between the print belt 4 and the decoupling belt 2 and below the paper transport path 1, and that guides the transport of the paper between the belts. A cold air blowing unit 3 is provided above the decoupling belt 2 and the guide unit 41 to press down the sheet S transported from the print belt 4. If the transport detection sensor 40 is to be provided in the cold air blowing unit 3, there is no space and it is difficult to arrange the sensor 40 because of the cold air blowing surface 25 on which the plurality of cold air blowing nozzles 5 are provided at even intervals of "5 mm or more and 10 mm or less" as described above. Therefore, in this embodiment, the transport detection sensor 40 is arranged in the guide unit 41 that is provided below the paper transport path 1 on the opposite side of the cold air blowing nozzles 5 as described above.

[0062] <Problems to be Solved by the Present Invention> As described above, in this embodiment, the transport detection sensor 40 is disposed below the paper transport path 1 of the sheet S, and the sensor light L is emitted vertically upward from a detection unit (not shown) of the transport detection sensor 40 to check the transport of the sheet S. At this time, as shown in Fig. 11, if the sensor light L of the transport detection sensor 40 hits the opposing cold air blowing nozzle 5 when the sheet S is not passing, the sensor light L may be diffused, which may lead to erroneous detection by the sensor.

[0063] <Effects of the present invention> 12(a) and 12(b) will be used below to describe the arrangement of the transport detection sensor 40 and the flat portion 42, which is a key feature of the present invention in Example 2. Fig. 12(a) is a partial perspective view from below of the cold air blowing unit 3, and Fig. 12(b) is a schematic diagram showing the arrangement of the transport detection sensor 40 and the flat portion 42 described below.

[0064] In order to solve the above-mentioned concerns, in this embodiment, as shown in Fig. 12(a), a flat surface 42 without irregularities is provided on the cold air blowing surface 25 provided on the cold air blowing unit 3 except for the cold air blowing nozzle 5. Then, as shown in Fig. 12(b), the transport detection sensor 40 and the flat surface 42 are arranged so that at least the flat surface 42 is vertically above the detection portion of the transport detection sensor 40. As a result, when there is no sheet S, the sensor light L of the transport detection sensor 40 is irradiated onto the flat surface 42, which can prevent the occurrence of diffuse reflection as described in the above-mentioned problem, and can suppress erroneous detection by the transport detection sensor 40.

[0065] In this embodiment, as shown in FIG. 12(a), the cold air blowing nozzles 5 are arranged at equal intervals in the conveying direction A of the sheet S and in the width direction B of the sheet S perpendicular to the conveying direction, based on the arrangement of the above-mentioned planar portion 42.

[0066] In this embodiment, a reflective photosensor is used as the transport detection sensor 40, and it is desirable that at least the flat portion 42 is black so as to be able to absorb the irradiated sensor light L. If the flat portion 42 is white, the distance between the transport detection sensor 40 and the flat portion 42 must be greater than in this embodiment so as to be at the non-detection distance of the sensor in order to prevent erroneous detection of the transported sheet S, which is not preferable since it affects the size of the main body and requires the provision of an installation space.

[0067] In this embodiment, the transport detection sensor 40 is described as being disposed between the print belt 4 and the decoupling belt 2, but the present invention is not limited to this, and the same effect can be obtained by the present invention even if the transport detection sensor 40 is provided between the decoupling belt 2 on the downstream side of the transport and the drying belt 7. Also, even if a large number of transport detection sensors 40 are disposed, the same effect can be obtained by arranging at least the flat portion 42 vertically above the detection portion of each transport detection sensor 40.

[0068] (Variation 1) In addition, the transport detection sensor 40 is not limited to the reflective photosensor described in the second embodiment, and even if it is a prism photosensor, the same effects as those of the first embodiment can be obtained. In the first modification, the configuration other than the transport detection sensor 40 is the same as that of the second embodiment.

[0069] In this modified example 1, a prism of the prism photosensor is disposed on the flat portion 42 described in the embodiment 2. The transport detection sensor 40 of the prism photosensor also detects the presence or absence of transport of the sheet S by reflection of the sensor light L, similar to the reflective photosensor of the embodiment 2. Therefore, the present invention can prevent diffuse reflection of the sensor light L and stably receive the reflected light, thereby making it possible to suppress erroneous detection of the transport detection sensor 40.

[0070] (Variation 2) Even if the transport detection sensor 40 that detects the transported sheet S is an actuator type photosensor, the present invention can provide the same effect of preventing erroneous detection by the sensor as in Example 2. In addition, in Modification 2, the configuration other than the transport detection sensor 40 is the same as in Example 2.

[0071] In the case where the transport detection sensor 40 is an actuator type photosensor, if the cold air blowing nozzle 5 is disposed vertically above the detection unit, the flag of the actuator type photosensor will be directly exposed to the wind blown from the nozzle, and there is a concern that the sensor will make a false detection when the sheet S is not being transported. Therefore, as described in the present invention, by disposing the transport detection sensor 40 so that at least the cold air blowing nozzle 5 is not vertically above the flag, which is the detection unit, the flag will not be directly exposed to the wind blown from the nozzle, and false detection by the transport detection sensor 40 can be suppressed. [Explanation of symbols]

[0072] 1 Paper transport path 2 Decoupling belt 3 Cold air blowing unit 4 Printed Belt 5 Cold air blowing nozzle 6 Drying section 7 Drying Belt 8 Hot air blowing unit 9 Heater roller 10 Hot air blowing nozzle 11 Suction hole 12 Hot air blowing surface 13 Blower fan 14 Air duct 15 Heater 16 Temperature Sensor 17 Intake duct 18 Aperture 19 Areas without openings 23 Blower fan 24 Air duct 25 Cool air blowing surface 27 Intake duct 28 Intake hole 30 Ribs 31 Inclined Surface 40 Transport detection sensor 41 Guide unit 42 Plane part 43 Cross section in the conveying width direction 44 Opening Surface 45 Duct 46 Inlet 47 Duct Right 48 Duct Left

Claims

1. an image forming apparatus comprising: a paper transport path for transporting a recording medium; a duct arranged opposite the paper transport path and having a plurality of blowing ports for blowing air onto the recording medium; an air supply duct upstream of the duct, an air blowing means for drawing air into the air supply duct, and a heater for heating the air to be blown onto the recording medium; the duct has a plurality of openings between the plurality of blowing ports, penetrating from a surface facing the paper transport path to an opposite surface; the duct is divided perpendicular to the continuous openings parallel to the transport direction, perpendicular to the paper transport direction, and sealed at the dividing portions.

2. 2. The image forming apparatus according to claim 1, wherein the duct is divided in parallel to a direction in which the air is blown onto the paper.

3. 2. The image forming apparatus according to claim 1, wherein the divided portion of the duct has a hook shape on a side of the nozzle for blowing onto the paper and a fixed shape on the opposite side.

4. A plurality of conveying units that convey the sheet from upstream to downstream; an airflow generating unit that generates an airflow for holding the sheet in the conveying unit; a duct for blowing an airflow toward the conveying section from above the sheet; A detection sensor capable of detecting conveyance of a sheet, The duct is provided vertically above the transport unit, and includes a plurality of airflow blowing ports on a surface facing the transport unit, the detection sensor is provided vertically below the duct and includes a detection unit that detects conveyance of a sheet, A sheet conveying device, wherein a portion vertically below the airflow blowing port is not the detection portion.

5. a conveying guide portion is provided in a space between the plurality of conveying portions in a sheet conveying direction, the duct is provided above the conveying section and the conveying guide section, The sheet transport device according to claim 4 , wherein the detection sensor is provided in the transport guide portion.

6. The detection sensor is a reflective photosensor, The duct has a flat surface portion without irregularities at a portion other than the airflow blowing port, 6. The sheet conveying device according to claim 4, wherein the flat portion is located vertically above the detection portion.

7. 6. The sheet conveying device according to claim 4, wherein the detection sensor is a prism photosensor.

8. 6. The sheet conveying device according to claim 4, wherein the detection sensor is an actuator type photosensor.

9. The sheet conveying device according to any one of claims 1 to 8, characterized in that the spacing between the multiple air flow blowing ports provided in the duct in the conveying direction from upstream to downstream of the sheet is 5 mm or more and 10 mm or less.

10. 10. The sheet transport device according to claim 1, wherein the air blowing ports are disposed evenly on the duct with respect to the flat surface portion.

Images