Inkjet recording device

Abstract

To provide an inkjet recording device that makes it difficult for ink moisture or solvent evaporated due to heating a recording material to be attached to a conveyance guide arranged in a downstream of a pair of belts forming a fixation nip part.SOLUTION: An air blow unit 4500 is arranged above a conveyance guide unit 4300 so as to blow air to the conveyance guide unit 4300 that guides a recording material heated by a fixation belt unit 4100 to a cooling module 5000. Since the air blow unit 4500 blows air to the conveyance guide unit 4300 from upward, air containing ink moisture or solvent is easy to flow onto a cooling module 5000 side from a space above the conveyance guide unit 4300 where air containing ink moisture or solvent vaporized due to heating of a recording material is easy to be accumulated. The air containing ink moisture or solvent is sucked by an exhaust fan 5108 provided in the cooling module 5000 and discharged to the outside from the cooling module 5000.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus that forms an image with ink. [Background technology]

[0002] In inkjet recording devices that form images on recording materials using ink, a method of fixing the ink to the recording material using a pair of heating belts that contact each other is known. By using a pair of heating belts, a long fixing nip portion for nipping and transporting the recording material and fixing the ink to the recording material can be secured, thereby improving the fixability of the ink to the recording material (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-15290 Summary of the Invention [Problem to be solved by the invention]

[0004] The moisture and solvent contained in the ink evaporate when heated. When fixing ink to a recording material using a pair of heating belts, the moisture and solvent in the ink that evaporates due to heating in the fixing nip can condense when the temperature inside the device drops. In terms of the conveyance direction of the recording material, a conveyance guide that guides the recording material that has passed through the fixing nip is located downstream of the pair of heating belts. When condensation occurs, the moisture and solvent adhere to the conveyance guide. If the moisture and solvent adhere to the conveyance guide, there is a risk that the recording material will become dirty or the recording material will jam.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an inkjet recording device in which the moisture and solvent from the ink vaporized by heating the recording material are less likely to adhere to the transport guide located downstream of a pair of belts that form a fixing nip portion. [Means for solving the problem]

[0006] An inkjet recording apparatus according to one embodiment of the present invention is an inkjet recording apparatus that ejects ink to form an image on a recording material, and includes a first belt, a second belt that contacts the first belt to form a nip portion, a heating unit that heats the first belt, a fixing unit that sandwiches and conveys the recording material with an ink image formed thereon at the nip portion and applies heat to fix the ink to the recording material, a cooling unit that is disposed downstream of the fixing unit in the conveying direction of the recording material and has a cooling fan that blows air onto the recording material conveyed from the fixing unit to cool the recording material, a first chamber in which the fixing unit is disposed, and The cooling unit is characterized by comprising: a partition wall that separates the first chamber from a second chamber in which a cooling unit is arranged, and that has a communication opening that connects the first chamber to the second chamber so that the recording material can pass through; a guide unit that is arranged in the first chamber and guides the recording material transported from the fixing unit to the cooling unit through the communication opening; a blowing fan that is arranged above the guide unit in the first chamber and blows air from above onto the guide unit; and an exhaust fan that is arranged upstream of the cooling unit in the transport direction of the recording material in the second chamber and exhausts air that is sent from the communication opening to the second chamber in response to the blowing of air by the blowing fan. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent moisture and solvent from ink vaporized by heating the recording material from adhering to the guide portion located downstream of the pair of first and second belts that form the nip portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an inkjet recording apparatus. [Figure 2] FIG. [Figure 3] FIG. 3 is a schematic diagram showing a recording material transport unit. [Figure 4] FIG. 10 is a perspective view showing a state in which the upper guide unit is closed. [Figure 5] FIG. 10 is a perspective view showing a state in which the upper guide unit is open. [Figure 6] FIG. 2 is a schematic diagram showing a cooling module. [Figure 7] FIG. 3 is a cross-sectional view showing a cooling section of the cooling module. [Figure 8] FIG. 1( a ) is a diagram for explaining the airflow volume, and FIG. 1( b ) is a diagram for explaining the airflow velocity. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Inkjet recording device> An embodiment of the present invention will now be described with reference to the drawings. First, an inkjet recording apparatus according to this embodiment will be described with reference to FIG. 1. The inkjet recording apparatus 100 according to this embodiment is a so-called sheet-fed inkjet recording apparatus that forms an image on a recording material using ink and a reaction liquid based on image information input from an external device such as a computer or a document reader. The recording material may be any recording material that can accept ink, such as paper such as plain paper or cardboard, plastic film such as a recording material for overhead projectors, specially shaped sheets such as envelopes or index paper, or cloth.

[0010] In this specification, the side on which a user stands when operating the inkjet recording apparatus 100 is referred to as the "front," and the opposite side is referred to as the "rear." Furthermore, the left side when viewed from the front is referred to as the "left," and the right side when viewed from the front is referred to as the "right." Figure 1 shows the inkjet recording apparatus 100 as viewed from the front.

[0011] 1, the inkjet recording apparatus 100 includes a feeding module 1000, a printing module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, an inverting module 6000, and a stacking module 7000. The recording material S supplied from the feeding module 1000 undergoes various processes as it is transported along the transport path within each module, and is finally discharged to the stacking module 7000.

[0012] The feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may each have a separate housing, and these housings may be connected to form the inkjet recording apparatus 100. For example, the housing 2010 of the printing module 2000 and the housing 3010 of the drying module 3000, the housing 3010 and the housing 4010 (first housing) of the fixing module 4000, and the housing 4010 and the housing 5010 (second housing) of the cooling module 5000 are connected to enable the transfer of the recording material S between the respective housings. Note that in this embodiment, the feeding module 1000, printing module 2000, drying module 3000, fixing module 4000, cooling module 5000, reversing module 6000, and stacking module 7000 may be arranged in a single housing.

[0013] The feeding module 1000 includes cassettes 1500a, 1500b, and 1500c that store recording materials S, and the cassettes 1500a to 1500c are arranged so that they can be pulled out toward the front to store the recording materials S. The recording materials S are fed one by one in each of the cassettes 1500a to 1500c by a separation belt and a conveying roller, and are conveyed to the print module 2000. The number of cassettes 1500a to 1500c is not limited to three, and the number may be one, two, four, or more.

[0014] The print module 2000 includes a pre-imaging transport unit (not shown), a print belt unit 2200, and a recording unit 2300. The recording material S transported from the feeding module 1000 is transported to the print belt unit 2200 after the pre-imaging transport unit corrects the inclination and position of the recording material S. The recording unit 2300 is located opposite the print belt unit 2200 across the transport path of the recording material S. The recording unit 2300 forms an image by ejecting ink onto the recording material S from above using multiple print heads as the belt transports the recording material S. The ink-ejecting print heads are aligned along the transport direction of the recording material S. In this embodiment, the unit has a total of five line-type print heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), as well as reaction liquids. Clearance between the recording material S and the print heads is ensured by transporting the recording material S by the print belt unit 2200.

[0015] The number of ink colors and recording heads is not limited to the five mentioned above. The inkjet method can be a method using a heating element, a piezoelectric element, an electrostatic element, or a MEMS (Micro Electro Mechanical Systems) element. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube. The ink contains 0.1% to 20.0% by mass of a resin component, water, a water-soluble organic solvent, coloring material, wax, additives, etc., based on the total mass of the ink.

[0016] When the recording material S on which an image is formed by the recording unit 2300 is transported by the print belt unit 2200, it is detected by an in-line scanner (not shown) arranged downstream of the recording unit 2300 in the transport direction of the recording material S. Here, the misalignment and color density of the image formed on the recording material S are detected, and based on this image misalignment and color density, corrections are made to the images and densities to be formed on the recording material S thereafter.

[0017] In this embodiment, the print module 2000 includes a control unit 900, which controls the entire inkjet recording apparatus. The control unit 900 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ROM and RAM store various programs such as image formation jobs and various data such as image data. The CPU executes the image formation programs stored in the ROM and RAM to operate the inkjet recording apparatus 100 to form images. The RAM can temporarily store the results of calculations performed in conjunction with the execution of the various programs.

[0018] Furthermore, the print module 2000 is provided with an operation unit 200. For example, the operation unit 200 has a liquid crystal display unit 210 capable of displaying various information, and various displays such as various programs and data, or the completion of an image formation job or the occurrence of an error, can be displayed on the liquid crystal display unit 210. The operation unit 200 may be, for example, a touch panel capable of receiving inputs for starting various programs such as an image formation job and inputting various data in response to touch operations by the user. Note that the above-mentioned inputs for starting various programs and inputting various data may be input not only from the operation unit 200 but also from an external device such as a computer.

[0019] The drying module 3000 dries the recording material S on which an image has been formed by blowing hot air onto the recording material S. The drying module 3000 has a decoupling section 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 reduces the liquid content of the ink applied to the recording material S in order to improve the fixation of the ink to the recording material S by the subsequent fixing module 4000.

[0020] The recording material S on which the image has been formed is transported to a decoupling unit 3200 arranged in the drying module 3000. In the decoupling unit 3200, a frictional force is generated between the recording material S and the belt by the wind pressure of air blown from above the decoupling unit 3200, causing the belt to transport the recording material S. In this way, the recording material S placed on the belt is transported by frictional force, thereby preventing the recording material S from shifting as it is transported between the print belt unit 2200 and the decoupling unit 3200.

[0021] The recording material S conveyed from the decoupling section 3200 is conveyed by a drying belt unit 3300. A hot air blowing unit 3400 is arranged above the drying belt unit 3300, and air heated by a heater in the hot air blowing unit 3400 is blown onto the recording material S being conveyed by the drying belt unit 3300. This dries the ink and reaction liquid applied to the recording material S. When the ink and reaction liquid applied to the recording material S are heated by the drying module 3000 in this way, the ink is less likely to be absorbed in the areas of the recording material S where the ink is applied, and so-called cockling, in which the recording material S stretches and wrinkles locally, can be suppressed. Note that, as a heater for heating the air, for example, an electric heating wire or an infrared heater is preferred from the standpoints of safety and energy efficiency. In addition, as a drying method, in addition to the method of blowing hot air, a method of irradiating the recording material S with electromagnetic waves (ultraviolet rays, infrared rays, etc.), or a conductive heat transfer method by contact with a heating element may be used, or a combination of these may be used.

[0022] The fixing module 4000 has a fixing belt unit 4100. The fixing belt unit 4100, which serves as a fixing section, fixes ink onto the recording material S by passing the recording material S conveyed from the drying module 3000 between a heated upper belt unit and a lower belt unit.

[0023] The cooling module 5000 has a plurality of cooling sections 5001, which cool the high-temperature recording material S transported from the fixing module 4000. The cooling sections 5001 are arranged on both sides of the transport path of the recording material S and cool both sides of the recording material S. The cooling section 5001 uses a fan to draw air (outside air) from outside the housing 5010 into a cooling box to increase the pressure inside the cooling box, and cools the recording material S by blowing the air out of the cooling box through a nozzle under pressure (see FIG. 7 described below).

[0024] The cooling module 5000 is also provided with a conveying path switching unit 5002. The conveying path switching unit 5002 switches the conveying path of the recording material S depending on whether the recording material S is conveyed to the reversing module 6000 or conveyed to a double-sided conveying path for double-sided printing, in which images are formed on both sides of the recording material S.

[0025] The reversing module 6000 has a reversing section 6400. The reversing section 6400 reverses the recording material S being conveyed, and changes the front and back orientation of the recording material S when it is discharged to the stacking module 7000. The stacking module 7000 has a top tray 7200 and a stacking section 7500, and stacks the recording material S conveyed from the reversing module 6000.

[0026] During double-sided printing, the recording material S is conveyed to a conveyance path below the cooling module 5000 by the conveyance path switching unit 5002. The recording material S then passes through a double-sided conveyance path of the fixing module 4000, drying module 3000, print module 2000, and feeding module 1000, and is returned to the print module 2000. The double-sided conveyance section of the fixing module 4000 is provided with an inverting unit 4200 that inverts the recording material S. An image is formed with ink on the other side of the recording material S that has been returned to the print module 2000, and the recording material S is then discharged to the stacking module 7000 via the drying module 3000, fixing module 4000, cooling module 5000, and inverting module 6000.

[0027] <Fixing module> Next, the fixing module 4000 will be described in detail with reference to FIG. 2. As shown in FIG. 2, a fixing belt unit 4100 is provided above the fixing module 4000. The fixing belt unit 4100 receives the recording material S discharged from the drying module 3000 and has a substantially linear sheet transport path 400a that transports the recording material S to the cooling module 5000. A transport guide unit 4300 is disposed at the exit of this sheet transport path 400a, i.e., downstream of the fixing belt unit 4100 in the transport direction of the recording material S. In this embodiment, an air blower unit 4500 is disposed above the transport guide unit 4300. The transport guide unit 4300 and the air blower unit 4500 will be described later.

[0028] The fixing belt unit 4100 includes an upper belt unit 410 and a lower belt unit 420. The upper belt unit 410 is disposed vertically above the lower belt unit 420. The upper belt unit 410 includes an upper belt 411 as a first belt and multiple tension rollers around which the upper belt 411 is suspended. The upper belt 411 rotates in accordance with one of the multiple tension rollers driven by a drive motor M1 as a drive source. The lower belt unit 420 includes a lower belt 421 as a second belt, multiple tension rollers around which the lower belt 421 is suspended, and a pad 423 with an arc-shaped curved surface. The pad 423 is disposed so as to form a fixing nip with the upper belt 411 via the lower belt 421. Furthermore, the upper belt unit 410 and the lower belt unit 420 include heaters (4060a, 4060b) as heating units for heating the upper belt 411 and the lower belt 421, respectively.

[0029] The fixing module 4000 also has an upper door unit 43 that can be opened upward. The upper belt unit 410 of the fixing belt unit 4100 is disposed inside the upper door unit 43, and the upper door unit 43 is configured to be able to be opened upward integrally with the upper belt unit 410. The recording material S is nipped and conveyed in the fixing nip portion between the upper belt unit 410 and the lower belt unit 420. The lower belt 421 is disposed opposite the upper belt unit 410 when the upper door unit 43 is located in the closed position. At this time, the lower belt 421 and the upper belt 411 nip and convey the recording material S. The pressure in the fixing nip portion is determined by the tension and thickness of the upper belt 411 and the curvature of the pad 423. If the pressure in the fixing nip is too high, the ink on the recording material S may adhere to the upper belt 411 and peel off from the recording material S, so the pressure is preferably "1 Pa or more and 2000 Pa or less," and more preferably "1 Pa or more and 200 Pa or less."

[0030] If the curvature of the pad 423 becomes large, the difference in the conveyance path between the front and back of the recording material S becomes large, which may cause friction between the recording material S and the belt. If the curvature of the pad 423 becomes large, there is a risk that the recording material S itself may memorize the curved shape and curl, so it is desirable that the radius of curvature of the pad 423 be "50 mm or more." Furthermore, from the perspective of manufacturing precision, it is desirable that the radius of curvature of the pad 423 be "100,000 mm or less." Due to these constraints, in this embodiment, the tension of the upper belt 411 is set to 200 N, the thickness is set to "0.3 mm," the curvature of the pad 423 is set to "30,000 mm," and the nip pressure is set to "approximately 16 Pa."

[0031] This configuration enables uniform pressure application even in a wide nip. As a result, even when the temperature of the upper belt unit 410 is set to the melting point of wax or the boiling point of water, sufficient heat transfer to the recording material S can be achieved by increasing the contact time between the recording material S and the upper belt unit 410. However, if the nip continues to form after sufficient heat transfer, ink may adhere to the upper belt 411 and peel off from the recording material S, or the upper belt 411 may rub against the recording material S, causing image distortion. Therefore, a long contact time is not desirable. Therefore, the time required for the leading edge of the recording material S to enter the nip entrance and exit the nip exit is preferably between 0.5 and 4 seconds. In this embodiment, a pad 423 with a length of 900 mm in the sheet transport direction is used, the recording material S is transported at 700 mm / s, and the time required for the leading edge of the recording material S to completely exit the nip entrance is approximately 1.3 seconds. Since moisture is necessary for ink to penetrate the recording material S, it is preferable that the upper belt 411 and the lower belt 421 are impermeable to moisture so that when the recording material S becomes hot, the moisture evaporated from the surface of the recording material S does not escape through the upper belt 411 or the lower belt 421 that they come into contact with.

[0032] The fixing module 4000 is also provided with a top plate partition plate 4311a for forming an air layer between the top plate 4311b and the top plate 4311b to prevent the top plate 4311b from becoming too hot due to the heat generated by the heaters 4060a and 4060b. Specifically, a top plate duct 4311 is formed between the top plate partition plate 4311a and the top plate 4311b. Air from outside the housing 4010 passes through the top plate duct 4311 from the upstream end in the transport direction. Because the heat generated by the heaters 4060a and 4060b is blocked by the air flowing through the top plate duct 4311, the temperature of the top plate 4311b does not rise. Instead, the air in the top plate duct 4311 rises as the heat from the heaters 4060a and 4060b is transferred to the top plate partition plate 4311a. In this embodiment, the downstream end of the top plate duct 4311 in the transport direction communicates with the space inside the housing 4010 .

[0033] <Recording material transport unit> Next, the conveying guide unit 4300 will be described with reference to FIGS. 3 to 5 along with FIGS. 1 and 2. As shown in FIG. 3, the conveying guide unit 4300 as a guide section is disposed downstream of the fixing nip section N in the conveying direction of the recording material S, and conveys the recording material S that has passed through the fixing nip section N to the cooling module 5000. The recording material S is separated from the upper belt 411 by an upper separation claw 4303a, and separated from the lower belt 421 by a lower separation claw 4303b, and is then delivered to the conveying guide unit 4300.

[0034] The conveying guide unit 4300 includes an upper guide unit 4300a disposed on the upper belt unit 410 side and a lower guide unit 4300b disposed on the lower belt unit 420 side. The upper guide unit 4300a includes an upper belt outlet guide 4304a, an upper conveying roller 4306a, an upper conveying guide 4307a, and an upper surface temperature detection sensor 4310a. The lower guide unit 4300b includes a lower belt outlet guide 4304b, a lower conveying roller 4306b, a lower conveying guide 4307b, and a lower surface temperature detection sensor 4310b. In the vertical direction, the upper belt outlet guide 4304a and the lower belt outlet guide 4304b, and the upper conveying guide 4307a and the lower conveying guide 4307b are disposed opposite each other with a gap therebetween to allow the recording material S to pass through. The upper conveying roller 4306a and the lower conveying roller 4306b are rotatably disposed with the recording material S sandwiched therebetween.

[0035] In this embodiment, the upper conveying roller 4306a and the lower conveying roller 4306b are respectively disposed in the upper guide unit 4300a and the lower guide unit 4300b, but this is not limiting. For example, the upper conveying roller 4306a and the lower conveying roller 4306b may be integrally disposed as a pair of rollers in either the upper guide unit 4300a or the lower guide unit 4300b.

[0036] The recording material S heated by the fixing belt unit 4100 is conveyed by rotating upper conveying rollers 4306a and lower conveying rollers 4306b. At that time, the recording material S is conveyed while the upper surface of the recording material S is guided by an upper belt outlet guide 4304a and an upper conveying guide 4307a serving as first guide plates, and the lower surface of the recording material S is guided by a lower belt outlet guide 4304a and a lower conveying guide 4307b serving as second guide plates. As the recording material S passes between the upper conveying guide 4307a and the lower conveying guide 4307b, the front and back temperatures of the recording material S are detected by an upper surface temperature detection sensor 4310a and a lower surface temperature detection sensor 4310b, respectively. The upper surface temperature detection sensor 4310a and the lower surface temperature detection sensor 4310b are arranged to perform temperature control to determine whether the recording material S reaches a target temperature as it passes through the fixing belt unit 4100.

[0037] In this embodiment, an upper belt temperature detection sensor 4309a that detects the temperature of the upper belt 411 in a non-contact manner and a lower belt temperature detection sensor 4309b that detects the temperature of the lower belt 412 in a non-contact manner are provided. The upper belt temperature detection sensor 4309a is provided to control the heater 4060a to maintain the temperature of the upper belt 411 at a target temperature. The lower belt temperature detection sensor 4309b is provided to control the heater 4060b to maintain the temperature of the lower belt 412 at a target temperature.

[0038] A recording material detection sensor 4308 capable of detecting the recording material S without contact is disposed in the lower guide unit 4300b in order to detect a so-called jam, which occurs when the recording material S remains in the fixing belt unit 4100 or the conveyance guide unit 4300. If the recording material S remains in the conveyance guide unit 4300, the user must remove the remaining recording material S. Therefore, the upper guide unit 4300a is provided rotatable relative to the lower guide unit 4300b. Fig. 4 shows the upper guide unit 4300a in a closed state, and Fig. 5 shows the upper guide unit 4300a in an open state.

[0039] 4 and 5, the upper guide unit 4300a is provided so that the downstream end side in the conveying direction can rotate vertically relative to the lower guide unit 4300b about a rotation center shaft 4313. When the upper guide unit 4300a is in an open state, the upper belt outlet guide 4304a is positioned away from the lower belt outlet guide 4304b (see FIG. 3), the upper conveying guide 4307a is positioned away from the lower conveying guide 4307b, and the upper conveying roller 4306a is positioned away from the lower conveying roller 4306b. This opens the conveying path for the recording material S formed by the upper belt outlet guide 4304a and the lower belt outlet guide 4304b, the upper conveying guide 4307a and the lower conveying guide 4307b, and the upper conveying roller 4306a and the lower conveying roller 4306b. This allows the user to remove any recording material S remaining in the conveying path when a jam occurs. Furthermore, the user can open the upper guide unit 4300a and clean mainly the inner surfaces (sides facing the conveyance path) of the upper conveyance guide 4307a and the lower conveyance guide 4307b. A plurality of ventilation holes 4312 through which air from the blower unit 4500 passes are formed in the belt outlet guides (4304a, 4304b) and the conveyance guides (4307a, 4307b).

[0040] <Cooling module> Next, the cooling module 5000 will be described with reference to FIGS. 6 and 7. FIG. 6 is a schematic diagram showing the cooling module 5000, and FIG. 7 is a cross-sectional view showing the cooling section 5001 of the cooling module 5000. As shown in FIG. 6, the cooling module 5000 has a communication opening 5300 on the upstream side in the conveyance direction, which is open and allows the recording material S conveyed from the fixing module 4000 to be handed over, and an inlet guide 5107 is disposed at the communication opening 5300. Furthermore, an exhaust fan 5108 is disposed upstream of the cooling section 5001 in the housing 5010 in the conveyance direction of the recording material S to exhaust air blown from the communication opening 5300 into the housing 5010 in response to the air blown by the blowing fan. Note that the inlet guide 5107 preferably has a vent hole formed therein to ventilate the air near the belt outlet guides (4304a, 4304b).

[0041] The cooling module 5000 has a plurality of cooling sections 5001, which are arranged on both sides of a conveying path along which the recording material S is conveyed, and are arranged side by side in the conveying direction of the recording material S. Furthermore, with respect to the conveying direction of the recording material S, conveying roller pairs 5111, 5112, 5113, 5114, 5115, 5116, and 5117 for conveying the recording material S are arranged on both sides of the plurality of cooling sections 5001. The plurality of cooling sections 5001 cool both sides of the recording material S that is conveyed along the conveying path by the conveying roller pairs 5111 to 5117.

[0042] As described above, the cooling module 5000 is provided with a conveying path switching unit 5002 in order to switch the conveying path of the recording material S between when the recording material S is conveyed to the subsequent reversing module 6000 and when the recording material S is returned to the print module 2000 for double-sided printing on the recording material S. In the cooling module 5000, a plurality of cooling units 5001 and pairs of conveying rollers 5118, 5119, 5120, 5121, 5122, 5123, and 5124 are also arranged on the double-sided conveying path that returns the recording material S to the print module 2000.

[0043] As shown in FIG. 7, a cooling guide 5101 is disposed in the cooling section 5001 on the upstream side in the conveying direction. The cooling guide 5101 functions as a guide for the recording material S as it passes through. A number of nozzles 5102 are disposed on the guide surface of the cooling guide 5101. The box 5103 has a seamless box shape, and the cooling guide 5101 is fixed without any gaps to form a cooling box 5110. A cooling fan 5105 is disposed in the box 5103, and an air intake hole 5104 is formed to supply air to the cooling fan 5105. A conveying-side air intake duct 5106, which functions as a duct for supplying air to the cooling fan 5105, is disposed in the box 5103 on the air intake hole 5104 side. The cooling fan 5105 blows air out of the cooling box 5110. That is, the cooling box 5110 functions as a duct (second duct) through which the cooling fan 5105 blows air. The cooling box 5110 has an air outlet 5110a formed on the side of the conveying path along which the recording material S is conveyed. The recording material S conveyed from the fixing module 4000 is cooled by the air blown out from the cooling box 5110.

[0044] In the fixing module 4000 described above, the moisture and solvent in the ink applied to the recording material S are heated in the fixing nip N and vaporize, easily becoming trapped inside the housing 4010. The vaporized moisture and solvent increase the humidity in the exit area 4401 of the fixing nip N (see FIG. 3), which can cause condensation when the temperature inside the housing 4010 drops. When condensation occurs, the moisture and solvent adhere to the belt exit guides (4304a, 4304b) and conveyance guides (4307a, 4307b) shown in FIG. 3. If the moisture and solvent adhere to the belt exit guides (4304a, 4304b) and conveyance guides (4307a, 4307b), there is a risk that the recording material S will become soiled or that the recording material S will jam.

[0045] Therefore, in this embodiment, in order to suppress the occurrence of condensation due to evaporation of water or solvent in the ink, a blower unit 4500 is disposed above the transport guide unit 4300 as shown in Fig. 3, and the blower unit 4500 exhausts the air inside the housing 4010 to the outside of the housing 4010. The blower unit 4500 will be described below with reference to Fig. 3, Fig. 8(a) and Fig. 8(b).

[0046] <Blower unit> As shown in FIG. 3, the blower unit 4500 has a blowing fan 4501 and a blowing duct 4502 (first duct). The blowing duct 4502 has an air outlet 4502a formed on the transport guide unit 4300 side (guide unit side). In this embodiment, the blowing fan 4501 takes in air discharged into the housing 4010 (first housing) from the exhaust port 4311c formed in the top plate duct 4311, and blows the air from above onto the transport guide unit 4300 through the blowing duct 4502. By blowing air from above onto the transport guide unit 4300, the air in the exit region 4401 of the fixing nip portion N is exhausted to the outside of the housing 4010. In this embodiment, the air is discharged from the housing 4010 to the housing 5010 of the cooling module 5000.

[0047] As described above, the air in the top plate duct 4311 rises as heat from the heaters 4060a and 4060b is transferred to the top plate partition plate 4311a. Therefore, the heated air in the top plate duct 4311 is blown toward the conveying guide unit 4300 by the blowing fan 4501. This makes it possible to exhaust high-humidity air present in the exit region 4401 of the fixing nip N without cooling the belt exit guides (4304a and 4304b) and the conveying guides (4307a and 4307b). In addition, the belt exit guides (4304a and 4304b) and the conveying guides (4307a and 4307b) are provided with vents 4312 (see FIG. 6), which facilitates the flow of air from the blowing fan 4501 into the exit region 4401 of the fixing nip N. In this way, ventilation of the air in the exit area 4401 of the fixing nip portion N is promoted, which makes it easier to reduce the humidity inside the housing 4010.

[0048] The blowing fan 4501 operates by controlling a motor (not shown) by the control unit 900 (see FIG. 1). In this embodiment, the blowing fan 4501 operates when the upper belt 411 and the lower belt 421 are rotating, and does not operate when the upper belt 411 and the lower belt 421 are not rotating. That is, the control unit 900 operates the blowing fan 4501 when the inkjet recording apparatus 100 is forming an image or is in standby mode, but does not operate the blowing fan 4501 when the inkjet recording apparatus 100 is in sleep mode. Here, the standby mode refers to a waiting mode in which the inkjet recording apparatus 100 is ready to immediately start image formation on the recording material S in response to an input of an image formation job. The sleep mode refers to a mode in which power consumption is lower than that of the standby mode. When the inkjet recording apparatus 100 is in a power-on state, it transitions to the standby mode if a predetermined time has passed since the end of the image formation operation without an input of an image formation job. Then, if a predetermined time has passed since the standby state without an image formation job being input, or if a power saving mode is selected from the operation unit 200, the standby state is shifted to a sleep state.

[0049] <About air volume> Next, the relationship between the optimal airflow volume for exhausting the air inside the housing 4010 to the housing 5010 side by the air blowing unit 4500 will be described with reference to Fig. 8(a). As shown in Fig. 8(a), the housings 4010 and 5010 have partition walls 4600 and 5600 that separate a first chamber in which the fixing belt unit 4100 is disposed from a second chamber in which the cooling section 5001 is disposed, and that have communication openings 4400 and 5300 that communicate between the first chamber and the second chamber so that the recording material S can pass through.

[0050] Air flowing in from the top panel duct 4311 by the blowing fan 4501 passes through the blowing duct 4502 and is blown onto the transport guide unit 4300 at an air volume of "Q1". The air volume "Q1" is the volume of air blown out from the blowing duct 4502 by the blowing fan 4501. In this embodiment, in the cooling module 5000, the airflow from the cooling unit 5001 bounces back and is sucked in by the exhaust fan 5108, thereby generating an airflow with an air volume of "Q2" in the opposite direction to the airflow blown out from the blowing duct 4502 by the blowing fan 4501. The exhaust fan 5108 is positioned higher than the communication port 5300 within the housing 5010 so as to guide the airflow generated from the cooling section 5001 and the airflow generated by the blowing fan 4501 upwards in the housing 5010 when the air inside the housing 4010 is drawn into the housing 5010 by the air blown from the blowing fan 4501.

[0051] In order to simultaneously exhaust the airflow of the blowing fan 4501 and the airflow of the cooling unit 5001 to the outside of the housing 5010, the air volume "Q3" of the exhaust fan 5108 is set so that "Q3-Q2>Q1". In this way, the air blown from the blowing fan 4501 can be exhausted to the outside of the housing 5010 by the exhaust fan 5108 without causing the high humidity air in the exit area 4401 of the fixing nip N to flow back or stagnate. In this embodiment, the air volume "Q1" of the blowing fan 4501 required to ventilate the high humidity air in the exit area 4401 of the fixing nip N is set to, for example, "0.3 m 3 / min, and the air volume "Q2" of the cooling unit 5001 is, for example, "1.0 m 3 Therefore, the air volume "Q3" of the exhaust fan 5108 is, for example, "1.5 m 3 / min".

[0052] <About wind speed> Next, the wind speed relationship of the airflow that is optimal for exhausting the air inside the housing 4010 to the housing 5010 side by the blower unit 4500 will be described using FIG. 8(b). In the present embodiment, as described above, the air blown by the blowing fan 4501 through the blowing duct 4502 toward the conveyance guide unit 4300 is intended to ventilate the air in the outlet region 4401 of the fixing nip portion N without retaining it. Therefore, the wind speed (V1) of the air blown by the blowing fan 4501 may be any wind speed that can ventilate the air in the outlet region 4401 of the fixing nip portion N. On the other hand, the air blown by the cooling unit 5001 toward the recording medium S is intended to efficiently cool the high-temperature recording medium S conveyed from the fixing module 4000. Therefore, the wind speed (V2) of the air blown by the cooling unit 5001 is preferably as large as possible so that the heat transfer efficiency to the recording medium S can be increased. In the present embodiment, the wind speed (V1) of the air blown by the blowing fan 4501 is the wind speed at the outlet 4502a (the first outlet) of the blowing duct 4502. The wind speed (V2) of the air blown by the cooling unit 5001 is the wind speed at the outlet 5110a (the second outlet) of the cooling box 5110.

[0053] In view of the above points in the present embodiment, the wind speed (V1) of the air blown by the blowing fan 4501 and the wind speed (V2) of the air blown by the cooling unit 5001 are set such that "V1 < V2". Here, if the relationship between the wind speed (V1) of the air blown by the blowing fan 4501 and the wind speed (V2) of the air blown by the cooling unit 5001 is "V1 > V2", there is a risk that the air blown by the blowing fan 4501 may cool the fixing belt unit 4100 or inhibit the cooling function of the cooling unit 5001 in the cooling module 5000. In the present embodiment, for example, a wind speed of "0.3 m / s" is required to ventilate the air in the outlet region 4401 of the fixing nip portion N. In that case, the wind speed (V1) of the air blown by the blowing fan 4501 is set to "2.0 m / s", and the wind speed of the air blown by the cooling unit 5001 is set to "33.0 m / s" for the purpose of cooling the recording medium S.

[0054] <Guide Coating> The main components of the substances that volatilize from the ink used in this embodiment are water and a water-soluble solvent (glycerin). Here, the surface tension of water is typically 72.75 mN / m, while the surface tension of glycerin is 63.4 mN / m. Conventionally, materials such as stainless steel are often used for the belt outlet guides (4304a, 4304b) and conveyance guides (4307a, 4307b), and the surface free energy of stainless steel is 700 to 1100 mN / m. In this case, the surface free energy of the guides is greater than that of water or glycerin, resulting in a smaller contact angle of the water or glycerin condensed on the guide. This causes the water or solvent to spread over the guide surface, forming pools on the guide surface. Furthermore, while solvents such as glycerin have a high boiling point and are difficult to volatilize, once condensed, water vapor containing the solvent volatilizes more slowly than water alone, making the condensation difficult to eliminate. Furthermore, since solvents such as glycerin have a higher viscosity than water, if liquid pools form due to condensation, the resistance to conveyance by the guide increases.

[0055] Therefore, in this embodiment, the belt outlet guides (4304a, 4304b) and the conveying guides (4307a, 4307b) are coated with a fluorine coating. The surface free energy of the fluorine coating is 18.5 mN / m, which is lower than that of water or glycerin. This increases the contact angle with droplets of water or glycerin that condense on the guides, making it difficult for the condensed water or glycerin to spread. This makes it easier for water or glycerin that adheres to the guides due to wind, vibration, its own weight, or friction with the recording material S to fall off, eliminating condensation and preventing it from puddling. This prevents an increase in the conveying resistance of the guides due to condensation of highly viscous solvents such as glycerin.

[0056] In this embodiment, a fluorine coating is used from a material that satisfies the condition that the surface free energy of the material used for the guide surface is smaller than the surface tension of glycerin, under the condition that "the material has a surface free energy of 60 mN / m or less." However, the material is not limited to a fluorine coating. For example, the guide may be formed or the guide surface may be coated with a material that satisfies the above condition, such as PFA or a resin material.

[0057] In this embodiment, the upper conveying roller 4306a is preferably configured with a plurality of roller portions 43061 spaced apart on the rotation shaft so that the air blown by the blowing fan 4501 can easily flow along the outer surface of the upper conveying guide 4307a (see FIG. 4). Also, the outer surface of the upper conveying guide 4307a is preferably provided with a plurality of ribs (not shown) protruding from the outer surface along the conveying direction of the recording material S and spaced apart in the width direction so that the air blown by the blowing fan 4501 can flow toward the housing 5010.

[0058] As described above, in this embodiment, the air blower unit 4500 is disposed above the conveyance guide unit 4300 so as to blow air onto the conveyance guide unit 4300, which guides the recording material S heated by the fixing belt unit 4100 to the cooling module 5000. Because the air blower unit 4500 blows air onto the conveyance guide unit 4300 from above, the air containing the ink moisture and solvent tends to flow toward the cooling module 5000 from the space above the conveyance guide unit 4300, where air containing the ink moisture and solvent vaporized as the recording material S is heated tends to accumulate. The air containing the ink moisture and solvent is then sucked in by the exhaust fan 5108 provided in the cooling module 5000, making it more difficult for the air to flow toward the fixing belt unit 4100 but more likely to flow toward the cooling module 5000, and can then be exhausted from the cooling module 5000 to the outside. In this way, air containing the moisture and solvent of ink is less likely to accumulate in the space above the transport guide unit 4300, so the moisture and solvent of ink are less likely to adhere to the transport guide unit 4300. [Explanation of symbols]

[0059] 100...inkjet recording apparatus, 411...first belt (upper belt), 421...second belt (lower belt), 900...controller, 4010...first housing (housing), 4060a...heating unit (heater), 4100...fixing unit (fixing belt unit), 4300...guide unit (conveying guide unit), 4304a...first guide plate (upper belt outlet guide), 4304b...second guide plate (lower belt outlet guide), 4307a...first guide plate (upper conveying guide), 4307b...second guide plate (lower conveying guide), 4 311b...top plate, 4311...top plate duct, 4311c...exhaust port, 4400, 5300...communication port, 4501...blowing fan, 4502...first duct (blowing duct), 4502a...first air outlet (air outlet), 4600, 5600...partition wall, 5001...cooling section, 5105...cooling fan, 5108...exhaust fan, 5010...second housing (housing), 5110...second duct (cooling box), 5110a...second air outlet (air outlet), M1...driving source (driving motor), N...nip section, S...recording material

Claims

1. An inkjet recording apparatus that ejects ink to form an image on a recording material, a fixing section including a first belt, a second belt contacting the first belt to form a nip section, and a heating section for heating the first belt, wherein a recording material on which an image has been formed with ink is sandwiched and conveyed through the nip section, and heat is applied to fix the ink to the recording material; a cooling unit disposed downstream of the fixing unit in the conveying direction of the recording material, the cooling unit having a cooling fan that blows air onto the recording material conveyed from the fixing unit to cool the recording material; a partition wall that separates a first chamber in which the fixing unit is disposed and a second chamber in which the cooling unit is disposed, and that has a communication opening that communicates the first chamber with the second chamber so that the recording material can pass through; a guide portion disposed in the first chamber and configured to guide the recording material conveyed from the fixing portion to the cooling portion through the communication opening; a blowing fan disposed above the guide portion in the first chamber and configured to blow air onto the guide portion from above; an exhaust fan disposed in the second chamber upstream of the cooling unit in the conveying direction of the recording material, for exhausting air sent from the communication port to the second chamber in response to air blown by the blowing fan; An inkjet recording apparatus characterized by:

2. a first duct having a first air outlet formed on the guide portion side, the first duct having the blowing fan disposed therein and blowing air from the first air outlet; a second air outlet formed on the side of a conveying path along which the recording material is conveyed, and a second duct in which the cooling fan is disposed and which blows out air from the second air outlet, a wind speed of the air blown out from the first air outlet by the blowing fan is higher than a wind speed of the air blown out from the second air outlet by the cooling fan; 2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

3. A first housing; a second housing connected to the first housing downstream in the conveying direction so as to be able to deliver the recording material; the first housing and the second housing each have the partition wall in which the communication port is formed, the fixing portion and the guide portion are housed in the first housing, The cooling unit is housed in the second housing.

2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

4. a top plate duct disposed in the first housing between the top plate and the fixing unit to allow outside air to pass through from outside the first housing to cool the top plate; the blowing fan takes in air discharged into the first housing through an outlet formed in the top plate duct and blows the air onto the guide portion.

4. The inkjet recording apparatus according to claim 3,

5. the guide portion has a first guide plate that guides the upper surface of the recording material and a second guide plate that guides the lower surface of the recording material, The surface of the first guide plate is coated with fluorine.

2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

6. a drive source that drives the first belt, a control unit for controlling the drive source and the blowing fan, the control unit operates the blowing fan in a standby state in which the first belt is rotating and the image forming unit is waiting for image formation, and does not operate the blowing fan in a sleep state in which the first belt is not rotating and power consumption is less than in the standby state.

2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

Images