Image formation device

Abstract

To solve such the problem with an inkjet image formation device including a dryer that, when an exterior is located in the vicinity of the dryer, the heat propagates to the exterior and increases the temperature of the exterior, whereas existing configuration includes an air intake path for a dryer between an exterior and the dryer to cool the exterior, thereby cooling the exterior while suppressing the power consumption.SOLUTION: In an image formation device, enlarging a cross-sectional area of a circulation port inside a dry part so as to be larger than a sectional area of an air intake port from the outside can prevent a reversed flow from the circulation port to the intake port, thereby making an interval between the exterior and a dryer become an air intake path for the dryer to inhibit a rise of the temperature of the exterior.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a drying device that dries a recording medium, and an inkjet recording apparatus equipped with the drying device. [Background technology]

[0002] Some inkjet recording devices are equipped with a drying device for evaporating the water content of the ink and drying the recording medium. Most drying devices expedite the drying of the recording medium by blowing hot air onto the recording medium on which the ink is carried.

[0003] In the ink drying unit described in Patent Document 1, the ink is also dried by blowing hot air onto the recording medium. In such a configuration in which ink is evaporated by blowing hot air, the inside of the machine is constantly filled with the blown hot air to promote evaporation of the ink, thereby maintaining the inside of the machine at a high temperature. In order to prevent heat from being conducted from the inside of the machine to the exterior and causing the exterior to become hot, a mechanism is required to use a heat insulating material for the exterior member or to cool the exterior. However, when a heat insulating material is used for the exterior member, the cost of the product increases. In addition, when the exterior is cooled, heat is taken from the inside of the machine and exhausted, which is a problem in that the power consumption required to maintain the inside of the machine at a high temperature increases.

[0004] To address the above-mentioned problems, Patent Document 2 proposes a mechanism for cooling the exterior by using the space between the exterior and the drying device as an air intake path for the drying device. This mechanism can reduce power consumption by taking in air warmed by cooling the exterior into the drying unit.

[0005] In addition, drying devices generally use a heater to heat the air and blow it onto the paper as hot air, which tends to consume a lot of power. Therefore, it is desirable to circulate the hot air blown onto the paper inside the machine and have it merge with the hot air sucked in by the suction transport section, rather than simply exhausting it outside the machine, to perform drying more efficiently. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5980622 specification Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional configuration had the following problem. That is, in such a drying device, when the hot air sucked in by the suction conveying unit merges with the air flowing through the intake air path or the hot air circulating inside the drying device, the hot air flows back into each path. When the hot air flows back into the intake air path, the temperature in the intake air path rises, and the exterior becomes hot.

[0008] In view of the above-mentioned problems, it is an object of the present invention to enable hot air sucked in by a suction and conveyance section to join the intake path without flowing back. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the image forming apparatus of the present invention is an inkjet image forming apparatus having a transport path along which a printing object is transported, a drying device equipped with a heater which blows warm air toward the printing object, an air inlet to the heater, an air intake port which draws in air from outside the image forming apparatus, an exhaust port which exhausts air inside the image forming apparatus to the outside of the image forming apparatus, an air intake path which is arranged along the front exterior of the image forming apparatus and near the exterior of the top surface of the image forming apparatus, a circulation path which circulates air inside the apparatus, and a junction where the circulation path and the air intake path join and are connected to the air inlet, and is characterized in that the cross-sectional area of ​​the circulation path is larger than the cross-sectional area of ​​the air intake path. Effect of the Invention

[0010] According to the configuration of the present invention, the backflow of the hot air sucked by the suction transport section into each flow path is prevented, so that the space between the exterior and the drying device can be used as an intake path for the drying device, and the temperature rise of the exterior can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a drying module. [Diagram 3] FIG. 2 is a schematic perspective view of a drying module. [Figure 4] FIG. [Diagram 5] FIG. 11 is a side cross-sectional view of a drying unit of a modified example. [Figure 6] FIG. 2 is a schematic cross-sectional view of a drying belt unit. [Figure 7] FIG. 2 is an explanatory diagram showing a schematic configuration of a suction unit. [Figure 8] FIG. 2 is an explanatory diagram showing a schematic configuration of a suction unit. [Figure 9] FIG. 4 is an explanatory diagram showing the configuration of a roller unit. [Figure 10] 11 is a graph showing a change in static pressure with respect to the air volume in a suction space. [Figure 11] 4 is a flowchart for controlling the suction pressure of the drying belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 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.

[0013] <Image forming device> An inkjet recording apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] The print module 2000 has a pre-imaging registration correction unit (not shown), a print belt unit 2200, and a recording unit 2300. The sheet S conveyed from the paper feed module 1000 has its inclination and position corrected by the pre-imaging registration correction unit, and is conveyed to the print belt unit 2200. The recording unit 2300 is disposed at a position facing the print belt unit 2200 with respect to the conveying path. The recording unit 2300 is a sheet processing unit that performs recording processing (printing) on ​​the conveyed sheet S from above with a recording head to form an image. The sheet S is attracted and conveyed by the print belt unit 2200, so that a clearance with the recording head is secured. 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. Note that the number of colors and the number of recording heads are not limited to five. The inkjet method may 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, or the like. Ink of each color is supplied to the recording head from an ink tank (not shown) via an ink tube. The sheet S printed by the recording section 2300 is transported by the print belt unit 2200, and an in-line scanner (not shown) arranged downstream of the recording section in the transport direction can detect the misalignment and color density of the image formed on the sheet S and correct the printed image.

[0018] The drying module 3000 has a decoupling section 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 to the sheet S by the recording section 2300 and enhances the fixation of the sheet S and the ink. The sheet S printed by the recording section 2300 of the print module 2000 is transported to the decoupling section 3200 arranged in the drying module 3000. The decoupling section 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. The sheet S transported from the decoupling section 3200 is adsorbed and transported by the drying belt unit 3300, and at the same time, hot air is applied from the hot air blowing unit 3400 arranged above the belt to dry the ink-applied surface of the sheet S. In addition, 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 using contact with a heating element.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] <Drying function section> Next, the drying function section 3010 of the drying module 3000 according to the present invention will be described in detail with reference to Fig. 2, Fig. 3, and Fig. 6. Fig. 2 and Fig. 3 are a schematic cross-sectional view and a schematic perspective view, respectively, for explaining the configuration of the drying module 3000. Fig. 6 is a schematic cross-sectional view for explaining the configuration of the drying belt unit 3300.

[0024] 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.

[0025] The upstream portion of the drying function portion 3010 has a decoupling portion 3200 composed of a decoupling belt unit 3200 and a cold air blowing unit 3100, and the sheet S is conveyed by pressing it against the decoupling belt 3201 by blowing cold air from the vertically upper side of the decoupling belt unit 3201. When the leading edge of the sheet S reaches the decoupling belt 3201 of the drying module 3000, the trailing edge side of the sheet S is still on the print belt unit 2200 of the print module 2000. On the print belt unit 2200, printing is being performed on the sheet S, and for this reason, the sheet S is conveyed by suction on the print belt unit 2200. In order not to disturb this printing process, the force pressing the sheet S against the decoupling belt 3201 is weaker than the suction force of the print belt unit 2200, and the decoupling belt 3201 is driven at a speed slightly faster than that of the print belt unit 2200. That is, while the rear end side of the sheet S is on the print belt unit 2200, the sheet S is configured to always slide against the decoupling belt 3201. On the other hand, the moment the rear end of the sheet S leaves the area of ​​the print belt unit 2200, the transport of the sheet S becomes dependent on the decoupling belt 3201. At this time, it is necessary to control the blowing force of the cold air blowing unit 3100 so that the paper does not slip due to the resistance to transport. Therefore, the wind speed from the cold air blowing nozzle is controlled to a predetermined pressure using a pressure sensor provided inside the unit and an intake fan provided in the intake section to apply a blowing force to the sheet S. The blowing unit 3100 is provided with many blowing holes for passing air so that a uniform pressing force can be applied to the sheet S.

[0026] The downstream of the drying function section 3010 has a drying section composed of a drying belt unit 3300 and a hot air blowing unit 3400, in which the sheet S is fixed on the belt by sucking it with the drying belt unit 3300, and hot air is blown from above vertically to dry the sheet S, and the sheet S is transported while suppressing waviness called cockling. In order to quickly dry the sheet S, the surface temperature of the drying belt 3301 is controlled to a predetermined temperature via a temperature sensor provided inside the drying belt unit 3300 and a heater roller 3351 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 is controlled to a predetermined pressure using a pressure sensor provided inside the unit and an intake fan provided in the intake section, and the ink on the sheet S is dried. The hot air blowing unit 3401 has a hot air blowing nozzle 3402 provided with a number of hot air blowing holes 3403 for passing air so that the sheet S can be dried uniformly.

[0027] As shown in FIG. 6, the drying belt unit 3300 includes a drying belt 3301, a heater roller (first roller) 3331, a driving roller (second roller) 3351, and a suction unit 3360. The heater roller 3331 and the driving roller 3351 are arranged parallel to the width direction Y of the drying belt 3301 perpendicular to the conveying direction X in which the sheet S is conveyed, and stretch the drying belt 3301. The driving roller 5 receives a driving force from the outside and rotates, thereby driving the drying belt 3301 in the conveying direction X. The heater roller 4 rotates together with the driving of the drying belt 3301. The suction unit 3360 sucks the sheet S in a direction in which the sheet S sticks to the conveying surface (first surface) 31, which is the surface of the drying belt 3301 and carries and conveys the sheet S, and the sheet S is conveyed while being sucked onto the drying belt 3301. The drying belt 3301 is provided with a large number of suction holes 3371 in order to uniformly suck the sheet S. The distance from the suction end position of the print belt unit 2200 to the suction start position of the drying belt 3301 is set to be longer than the maximum sheet length. EXAMPLES

[0028] The configuration of the hot air blowing part 3400 will be described below with reference to Fig. 4. As shown in Fig. 4, the hot air blowing part 3400 is surrounded by a front exterior 3415, a top exterior 3416, and a back exterior 3417. The hot air blowing part 3400 further includes a hot air blowing unit 3400 therein.

[0029] The front exterior 3415 has an intake port 3410 and an intake fan 3412 for taking in outside air. The rear exterior 3417 has an exhaust port 3411 for exhausting air in the hot air blowing section 3400 to the outside of the machine. A cooling duct 3413 is formed between the hot air blowing section 3400 and a part of the front exterior 3415, the top exterior 3416, and the rear exterior 3417. The cooling duct 3413 reaches the junction 3420 through a cooling duct outlet 3414, and communicates with an interior air circulation outlet 3424 through which the air inside the machine circulates, which will be described later, and an air inlet 3421 of the hot air blowing unit 3400. At the junction 3420, a humidity sensor 3422 is provided between the interior air circulation outlet 3424 and the air inlet 3421, and measures the humidity inside the machine. The humidity inside the machine is accurately measured by measuring the humidity of the air between the inside air circulation outlet 3424 and the blower fan 3404. The rotation of the intake fan 3412 is controlled based on the measured humidity, and the humidity inside the machine is controlled to be kept below 10% by appropriately taking in outside air.

[0030] The hot air blowing unit 3400 is composed of a blower fan 3404, a blower duct 3405, a heater 3406, and a temperature sensor 3407. The blower fan 3404 is an axial flow fan, but may be another blower source such as a sirocco fan. The heater 3406 is composed of a sheath heater, but may be another heat source such as a Kanthal heater. The blower duct 3405 has a heater 3406 and a temperature sensor 3407 inside, and the blowing side of the blower fan 3404 is connected to the end of the blower duct 3405. The heater 3406 is disposed downstream of the blowing path of the blower fan 3404. The surface of the heater 3406 facing the sheet S further downstream is a hot air blowing surface, and is provided with a plurality of hot air blowing holes 3403. The temperature sensor 3407 is disposed on the upper surface inside the duct facing the hot air blowing holes 3403. The current for generating heat from the heater 3406 is controlled according to the temperature of the temperature sensor 3407 .

[0031] Next, the configuration of the suction unit 3360 in the drying belt unit 3300 will be described with reference to Figs. 7, 8, 9, and 10. Figs. 7 and 8 are explanatory diagrams showing a schematic configuration of the suction unit 3360 of the present invention. Fig. 9 is an explanatory diagram showing the configuration of the roller unit 3363. Fig. 10 is a graph showing the change in static pressure with respect to the air volume in the suction space 3361.

[0032] The suction unit 3360 is composed of a frame 3362, a plurality of dryer belt suction fans 3366, and a plurality of roller units 3363. The frame 3362 is disposed inside the dryer belt 3301, and the dryer belt suction fan 3366 is connected to the frame 3362 and communicates with the frame 3362 through a suction opening 3362b provided in the frame 3362. The frame 3362 also has an opening 3362a facing the rear surface (second surface) 3301b of the dryer belt 3301, and a suction space 3361 partitioned by the dryer belt 3301 and the frame 3362 is formed. The dryer belt suction fan 3366 sucks air from within the suction space 3361 to create a negative pressure within the suction space 3361, and sucks the sheet S through the opening 3362a and the suction holes of the dryer belt 3301. The air sucked by the dryer belt suction fan 3366 is exhausted to the outside of the dryer belt unit 3300 through a duct 9 communicating with the dryer belt suction fan 3366. In this embodiment, the dryer belt suction fan 3366 is an axial flow fan, but other suction means such as a sirocco fan may also be used.

[0033] Here, in the area where the sheet S is on the drying belt 3301, the suction holes are blocked and the air does not flow. Therefore, the volume of the air sucked in the suction space 3361 decreases and the air flow rate decreases, so the pressure of the sucked air increases. That is, the pressure sucking the drying belt 3301 changes depending on the timing when the sheet S is placed on the drying belt 3301 and positioned in the area where the suction space 3361 is located. At this time, the speed of the drying belt 3301 may fluctuate due to the change in the pressure sucking the drying belt 3301 during printing operation. In addition, there is a possibility that a problem such as an increase in the load torque of the driving motor due to the increase in the pressure of the drying belt 3301 may occur. Therefore, as in this embodiment, multiple drying belt suction fans 3366 are arranged in parallel to suck one suction space 3361. Here, when three fans are arranged in parallel as shown in FIG. 7, the slope of the curve showing the change in pressure P relative to the change in air flow Q becomes gentler, and the change in pressure P relative to the change in air flow ΔQ becomes smaller (ΔP3<ΔP1). Therefore, by arranging a plurality of drying belt suction fans 3366 in parallel as in this embodiment, even if the sheet S is present on the drying belt 3361 and the suction pressure in the suction space 3361 rises, the amount of change in the suction pressure is small. Therefore, the effect of the load fluctuation that the drying belt 3361 receives due to the suction pressure can be reduced.

[0034] In addition, in a configuration in which hot air is blown toward the sheet S from above the drying belt unit 3300, it is desirable to pull the sheet S with a strong suction pressure so that the sheet S does not become unstable in conveyance due to positional deviation, skew, floating, waving, curling, etc. of the sheet S. Here, in order to suppress the displacement of the drying belt 3301 and stabilize the conveyance of the sheet S even if the drying belt 3301 is pulled by a strong suction pressure, a plurality of roller units 3363 are arranged in the suction unit 3360 as backups that receive the back surface 3301b of the drying belt 3301. As shown in FIG. 6, the roller unit 3363 has a plurality of rollers 3364 rotatably supported by one shaft 3365. The roller units 3363 are arranged in a frame 3362 such that the shaft 3365 is arranged substantially parallel to the width direction Y of the drying belt 3301, and a plurality of roller units 3363 are arranged from the upstream side to the downstream side along the conveyance direction X. In order to stabilize the planar state of the drying belt 3301, it is desirable to arrange the multiple rollers 3364 so as to back up the area of ​​the suction space 3361 as widely and uniformly as possible, and to set the pitch between the multiple rollers 3364 so as to block as few of the multiple suction holes 3371 in the drying belt 3301 as possible.

[0035] As an example, the roller 3364 has a diameter of about 9 to 10 mm, and a plurality of rollers 3364 are provided on one shaft 3365 at approximately equal intervals with a pitch of 11 to 12 mm, and the roller units 3363 are arranged with the shafts 3365 spaced at intervals of about 8 mm in the conveying direction X. Each roller 3364 is rotatably supported, and rotates following the movement of the drying belt 3301 while contacting the back surface 32 of the drying belt 3301. The plurality of rollers 3364 may be configured to rotate relative to the shaft 3365, or may be configured to rotate simultaneously with the shaft 3365. Since the plurality of rollers 3364 are driven by the drying belt 3301, even if the plurality of rollers 3364 hit each other, the resistance applied to the drying belt 3301 is small, and wear of the drying belt 3301 can be minimized. In this way, the drying belt 3301 hits the plurality of roller units 3363, and the sheet S can be conveyed while maintaining a stable flat state.

[0036] <Suction pressure control> Furthermore, by controlling the rotation speed of the drying belt suction fan 3366 using a sensor, it is possible to stabilize the suction pressure received by the drying belt 3301. Hereinafter, a description will be given with reference to the flow chart of FIG.

[0037] A pressure sensor (pressure detection unit) 3368 is provided in the suction space 3361, which detects the suction pressure in the suction space 3361 and adjusts the rotation speed of the dryer belt suction fan 3366 according to the detection result. Specifically, when the detection result of the pressure sensor 3368 falls below the threshold value of the suction pressure required for the dryer belt 3301 to support the sheet S, the rotation speed of the dryer belt suction fan 3366 is increased to increase the suction pressure. As described above, the temperature of the dryer belt unit 3300 increases due to the hot air discharged from the hot air blowing unit 3400 and the heat of the heater roller 3351. In general, when the temperature increases, the volume of air increases and the pressure decreases. Therefore, the temperature in the suction space 3361 increases, and the suction pressure decreases and may fall below the desired suction pressure. Therefore, by controlling the suction pressure in the suction space 3361 using the pressure sensor 3368, the suction pressure required to adsorb the sheet S to the dryer belt 3301 can be maintained.

[0038] As described above, when the sheet S is on the drying belt 3301, the suction holes are blocked, and the suction pressure increases. Therefore, a sheet detection sensor (recording material detection unit) 3369 that detects the sheet S passing on the sheet transport path 1 is disposed at a position upstream of the drying belt unit 3300 in the transport direction of the sheet transport path 1. The sheet detection sensor 3369 detects the sheet S before it reaches the drying belt 3301. This makes it possible to predict the timing when the sheet S will reach the drying belt 3301, and to reduce the rotation speed of the multiple drying belt suction fans 3366 in advance, thereby reducing the suction pressure that the drying belt 3301 receives. Even if the sheet S is on the drying belt 3301, the suction pressure of the drying belt 3301 can be set so as not to exceed the maximum allowable value.

[0039] <Air flow in the drying section> Next, the air flow in the hot air blowing section 3400 will be described with reference to FIG. 4. The arrows in FIG. 4 indicate the air flow. When the intake fan 3412 is driven, outside air at 20 to 30° C. is sucked in from the intake port 3410, passes through the cooling duct 3413 from the front of the main body to the top surface, and reaches the junction 3420 at the rear of the main body from the cooling duct outlet 3414. The hot air in the hot air blowing section 3400 passes through the suction hole 3371 of the drying belt 3301, passes through the drying belt suction fan 3366, passes through the exhaust duct 3367, and reaches the junction 3420 from the inside air circulation outlet 3424. In addition, the hot air inside the machine that cannot be sucked in from the suction hole of the drying belt 3301 also merges with the exhaust duct 3367 at the exhaust duct outlet 3372 and the inside air circulation outlet 3409. The air that reaches the junction 3420 from each duct is sucked into the blower fan 3404 of the hot air blowing unit 3401 from the air inlet 3421, and reaches the heater 3406 inside the blower duct 3405. The temperature of the blower duct 3405 is controlled to 80° C. by the heater 3406 and the temperature sensor 3407. The air heated by the heater 3406 passes through the hot air blowing hole 3403 and is blown onto the sheet S at a wind speed of 30 m / s. The hot air blowing section 3400 is always filled with air that has been heated by the heater 3406 and is hot, so that the hot air blowing section 3400 becomes hot and the inside of the hot air blowing section 3400 becomes hot, which promotes drying of the sheet S. In this way, by circulating the hot air as much as possible instead of exhausting it outside the machine, thermal energy is effectively utilized, which contributes to energy efficiency compared to heating the outside air from scratch.

[0040] Here, the suction pressure of the dry belt suction fan 3366 is 1000 [Pa], the intake pressure of the intake fan 3412 is 20 [Pa], and the flow rate in the exhaust duct 3367 is 480 [m 3 / min], and the flow rate in the cooling duct 3413 is 450 [m 3 / min]. At the junction 3420, the cross-sectional area of ​​the interior air circulation outlet 3424 is 0.7 [m 2 ], and the cross-sectional area of ​​the cooling duct outlet 3414 is 0.5 [m 2As a result, the static pressure of the interior air circulation outlet 3424 is 500 [Pa], and the static pressure of the cooling duct outlet 3414 is 200 [Pa], so that the pressure loss of the air flowing from the exhaust duct 3367 to the cooling duct 3413 becomes large. In addition, the wind pressure of the blower fan 3404 connected to the air inlet 3421 is 1000 [Pa], and the pressure at the junction is greater than the combined value of the static pressure from the interior air circulation outlet 3424 and the static pressure from the cooling duct outlet 3414. Therefore, it becomes possible for the air to pass through the air inlet 3421 and reach the blower fan 3404 while suppressing the air flowing back from the exhaust duct 3367 to the cooling duct 3413.

[0041] Furthermore, even when the in-machine air and the warm air from the dryer belt suction fan 3366 join together in the exhaust duct 3367, the cross-sectional area of ​​the in-machine air exhaust duct outlet 3409 is configured to be smaller than the cross-sectional area of ​​the exhaust duct outlet 3372 so that the warm air does not flow back into the in-machine air exhaust duct 3408.

[0042] Here, the exhaust duct outlet 3372 in the exhaust duct 3367 is disposed outside the area of ​​the drying belt 3301 and at a position higher than the drying belt 3301. This makes the paper transport path 1 of the sheet S less susceptible to the effects of turbulent air currents, such as rising air currents, caused by air exhausted from the exhaust duct outlet 3372, and enables stable transport of the sheet S.

[0043] Furthermore, the air used for drying contains a lot of moisture due to the evaporation of the ink. Therefore, in order to keep the humidity inside the machine constant, an intake fan 3412 is controlled using a humidity sensor 3407. Air sucked in from an intake port 3410 fills the inside of the hot air blowing unit 3400, and the air that filled the inside of the hot air blowing unit 3400 is exhausted to the outside through an exhaust port 3411. By sucking in outside air with less moisture from the intake port 3410 and replacing the air inside the hot air blowing unit 3400, it is possible to prevent the humidity inside the hot air blowing unit 3400 from increasing, which would make it difficult for the ink to evaporate.

[0044] <Effects of the present invention> As described above, outside air taken in from the front of the main body passes through the cooling duct 3413 and reaches the junction 3420 at the rear of the main body. The air flowing inside the machine joins at the junction 3420 and circulates inside the machine, but backflow to the cooling duct 3413 is suppressed. As a result, the air layer of the airflow that takes in outside air in the hot air blowing section 3400 located on the top side of the main body reduces heat conduction caused by the hot air in the air supply duct 3405 located below, and the top exterior 3416 can be suppressed from becoming too hot. At the same time, the heated air circulates inside the machine, reducing the power consumption of the heater 3406 and achieving energy efficiency. EXAMPLES

[0045] The second embodiment will be described with reference to FIG. 5. The same parts as those of the first embodiment will be omitted. In the case of the second embodiment, a communication guide 3423 is provided between the cooling duct outlet 3414 that draws in outside air at the junction 3420 and the interior air circulation outlet 3424 through which the interior air circulates. The communication guide 3423 is present from the rear exterior 3417 side in the junction 3420 toward the air inlet 3421. Furthermore, it has a length to a position closer to the air inlet 3421 than the duct mouth of each flow path. By providing such a guide 3423, the direction of air from each duct can be regulated. The direction of the wind from each duct is made parallel to the air inlet 3421. Therefore, even when air flows in from different directions at the junction 3420, it is possible to suppress the collision of the air flowing in from each duct, minimize the pressure loss of the dynamic pressure in each duct, and convert it into the suction pressure of the air inlet 3421. [Explanation of symbols]

[0046] 1 Paper transport path 2200 Print belt unit 3351 Heater roller 3366 Dry Belt Suction Fan 3367 Exhaust Duct 3372 Exhaust duct outlet 3371 Suction hole 3400 Hot air blowing section 3401 Hot air blowing unit 3403 Hot air blowing hole 3404 Blower Fan 3405 Air duct 3406 Heater 3407 Temperature Sensor 3408 Cabin air exhaust duct 3409 Cabin air exhaust duct outlet 3420 Junction 3421 Air inlet 3422 Humidity Sensor 3423 Connecting Guide 3424 Cabin air circulation outlet 3410 Air Intake 3411 Exhaust vent 3412 Intake fan 3413 Cooling Duct 3414 Cooling duct outlet 3415 Front exterior 3416 Top Exterior 3417 Rear Exterior

Claims

1. In an inkjet image forming apparatus, a transport path along which the print object is transported; A drying device having a heater that blows hot air toward the printing object; an air inlet to the heater; an intake port for taking in air from outside the image forming apparatus; an exhaust port for discharging air inside the image forming apparatus to the outside of the image forming apparatus; an intake path disposed along the vicinity of a front exterior of the image forming apparatus and a top exterior of the image forming apparatus; A circulation path for circulating air within the device; a junction portion where the circulation path and the intake path join and are connected to an air inlet, An image forming apparatus, wherein a cross-sectional area of ​​the circulation path is larger than a cross-sectional area of ​​the intake path.

2. 2. The image forming apparatus according to claim 1, wherein at the confluence portion, a communication guide existing between the circulation path and the intake path has a length extending to a position closer to the air inlet than the duct openings of each flow path.

3. 3. The image forming apparatus according to claim 1, further comprising a humidity detector arranged on said circulation path for detecting the humidity in the air.

Images