Ink jet printing device

Abstract

To prevent an occurrence of voltage flicker.SOLUTION: A drying module includes: a first unit including a first duct configured to guide air blown by a first fan and a first heater configured to generate heat by means electric power supplied from an AC power supply to heat air inside the first duct; and a second unit including a second duct configured to guide air blown by a second fan and a second heater configured to generate heat by means of electric power supplied from the AC power supply to heat air inside the second duct. The control unit is capable of executing a control pattern in which a first state and a second state are repeated, the first state being a state in which power is supplied to the second heater and power is not supplied to the first heater by starting power supply to the second heater simultaneously with stopping power supply to the first heater, from a state in which power is supplied to the first heater and power is not supplied to the second heater, and the second state being a state in which power is not supplied to both the first heater and the second heater.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In an image forming system that forms an image using ink, there are processes for drying a sheet and for blowing air onto the sheet. For example, a drying device has been proposed that transports a sheet by a belt and dries the sheet by blowing hot air onto the sheet (see Patent Document 1). In this drying device, a plurality of blowing units that blow air heated by a heater onto the sheet are arranged in the sheet transport direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-40053 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the drying device described in Patent Document 1 has multiple heaters, if these heaters are used simultaneously using commercial AC voltage as a power source, an inrush current may occur, which may lower the power supply voltage.On the other hand, if multiple heaters are used independently at different times, voltage fluctuations may occur frequently, which may cause voltage flicker that may cause effects such as flickering of lights around the drying device or malfunction of the device.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet recording apparatus that can suppress the occurrence of voltage flicker. [Means for solving the problem]

[0006] The inkjet recording apparatus of the present invention comprises an image forming section that forms an ink image on a sheet, a sheet transport section that transports the sheet carrying the ink image, and an air blowing device that blows air onto the sheet transported by the sheet transport section, the air blowing device comprising a first unit having a first fan that blows air, a first duct that guides the air blown by the first fan, and a first heating element that generates heat by power supplied from an AC power source to heat the air inside the first duct, a second fan that blows air, a second duct that guides the air blown by the second fan, and a first unit having a first heating element that generates heat by power supplied from the AC power source to heat the air inside the first duct, and a control unit that controls the power supply to the first heating element and the second heating element, wherein the control unit is capable of executing a control pattern that repeats a first state in which power is supplied to the first heating element and not to the second heating element, transitioning from a state in which power supply to the first heating element is performed and power supply to the second heating element is not performed, to a state in which power supply to the second heating element is performed and power supply to the first heating element is not performed, by simultaneously stopping power supply to the first heating element and starting power supply to the second heating element, and a second state in which power is not supplied to both the first heating element and the second heating element.

[0007] and an air blowing device that blows air onto the sheet being conveyed by the sheet conveying unit, the air blowing device including a first unit having a first fan that blows air, a first duct that guides the air blown by the first fan, and a first heating element that generates heat by power supplied from an AC power source to heat the air inside the first duct, a second unit having a second fan that blows air, a second duct that guides the air blown by the second fan, and a second heating element that generates heat by power supplied from the AC power source to heat the air inside the second duct, a third fan that blows air, a third duct that guides the air blown by the third fan, and a second unit having a second heating element that generates heat by power supplied from the AC power source to heat the air inside the third duct. and a third unit having a third heating element for heating air, and a control unit for controlling the power supply to the first heating element, the second heating element, and the third heating element, wherein the control unit is capable of executing a control pattern that repeats a third state in which power is supplied to the first heating element and not to the second and third heating elements, transitioning from a state in which power supply to the first heating element is supplied and not to the second and third heating elements, to a state in which power supply to the second heating element is stopped and simultaneously power supply to the second heating element is started, power is supplied to the second heating element, and not power is supplied to the first and third heating elements, to a state in which power supply to the second heating element is stopped and simultaneously power supply to the third heating element is started, power is supplied to the third heating element, and not power is supplied to the first and second heating elements, and a fourth state in which power is not supplied to any of the first, second, and third heating elements. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the occurrence of voltage flicker in an inkjet recording apparatus. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a cross-sectional view showing a schematic configuration of an inkjet recording apparatus according to a first embodiment. [Figure 2] 2 is a schematic cross-sectional view showing the configuration of a drying module, a print module, and a fixing module according to the first embodiment. FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view showing the configuration of a drying section of the hot air blowing unit according to the first embodiment. [Figure 4] FIG. 3 is a block diagram showing a control system of the hot air blowing unit according to the first embodiment. [Figure 5] A time chart showing the control pattern of a hot air blowing unit according to a comparative example, where (a) is a case where the on states of the first heater and the second heater are spaced apart without overlapping, and (b) is a case where the on states of the first heater and the second heater are shifted and overlap. [Figure 6] 4 is a time chart showing a control pattern of the hot air blowing unit according to the first embodiment. [Figure 7] 4 shows the allowable converted actual current value of voltage fluctuations relative to a commercial AC power supply in the hot air blowing unit according to the first embodiment. [Figure 8] 5 is a flowchart showing the operation procedure of the hot air blowing unit according to the first embodiment. [Figure 9] 10A is a schematic cross-sectional view showing the arrangement of a hot air blowing unit according to a second embodiment of the present invention, and FIG. 10B is a time chart showing the control pattern of the hot air blowing unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment The first embodiment will be described with reference to Figures 1 to 8. First, the schematic configuration of an inkjet recording apparatus 100 of this embodiment will be described with reference to Figure 1.

[0011] [Inkjet recording device] The inkjet recording apparatus 100 as an image forming apparatus of this embodiment uses an inkjet recording method in which ink is ejected to form an image on a sheet, and is a so-called sheet-fed inkjet recording apparatus that forms an ink image on a sheet using two liquids: a reaction liquid and ink. The sheet may be any recording material that can accept ink, such as paper such as plain paper or cardboard, plastic film such as an overhead projector sheet, specially shaped sheets such as envelopes or index paper, or cloth.

[0012] 1, the inkjet recording apparatus 100 of this embodiment includes a feeding module 1000, a printing module 2000, and a drying module 3000. The inkjet recording apparatus 100 further includes a fixing module 4000, a cooling module 5000, an inverting module 6000, and a stacking module 7000. The sheet 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.

[0013] The feeding module 1000 to the stacking module 7000 may each have a separate housing, and these housings may be connected to form the inkjet recording apparatus 100. Alternatively, the feeding module 1000, print 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.

[0014] The feeding module 1000 has storage cabinets 1500a, 1500b, and 1500c for storing sheets S, and the storage cabinets 1500a to 1500c are provided so that they can be pulled out to the front side of the apparatus to store sheets S. The front side of the apparatus refers to the front side of the inkjet recording apparatus 100, where the operation unit and the like are located and where the user stands when using or operating the apparatus. The sheets S are fed one by one in each of the storage cabinets 1500a to 1500c by a separation belt and a conveyance roller, and are conveyed to the print module 2000. The number of storage cabinets 1500a to 1500c is not limited to three, and the number may be one, two, four, or more.

[0015] The print module 2000 is an example of an image forming unit and forms an ink image on a sheet. The print module 2000 includes a pre-imaging registration correction unit (not shown), a print belt unit 2010, and a recording unit 2020. The sheet S transported from the feeding module 1000 has its tilt and position corrected by the pre-imaging registration correction unit before being transported to the print belt unit 2010. The recording unit 2020 is positioned opposite the print belt unit 2010 with respect to the transport path. The recording unit 2020 is an inkjet recording unit that forms an image by ejecting ink onto the transported sheet S from above using a recording head. Multiple recording heads that eject ink are arranged along the transport direction. In this embodiment, the unit has a total of five line-type recording heads corresponding to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), as well as reaction liquids. The sheet S is adsorbed and transported by the print belt unit 2010, ensuring clearance between the sheet S and the recording heads.

[0016] 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.

[0017] When the sheet S on which an image is formed by the recording unit 2020 is transported by the print belt unit 2010, it is detected by an inline scanner (not shown) arranged downstream of the recording unit 2020 in the transport direction of the sheet S. Here, the misalignment and color density of the image formed on the sheet S are detected, and based on this image misalignment and color density, the image to be formed on the sheet S, density, etc. are corrected.

[0018] The drying module 3000 is an example of an air blowing device that dries the sheet S by blowing air onto the sheet S being transported to the drying belt unit 5. As shown in FIG. 2, the drying module 3000 includes a decoupling unit 40, a drying belt unit 5, and a warm air blowing unit 8. The drying module 3000 reduces the liquid content of the ink and reaction liquid applied to the sheet S to improve the fixation of the ink to the sheet S by the subsequent fixing module 4000. The sheet S with an image formed thereon is transported to the decoupling unit 40 located within the drying module 3000. In the decoupling unit 40, frictional force is generated between the sheet S and the belt by the wind pressure of air blown from above, causing the sheet S to be transported by the belt. In this way, the sheet S placed on the belt is transported by frictional force, preventing the sheet S from shifting as it is transported between the print belt unit 2010 and the decoupling unit 40. The sheet S transported from the decoupling section 40 is adsorbed and transported by the drying belt unit 5, and hot air is blown onto the sheet S from the hot air blowing unit 8 arranged above the belt, thereby drying the ink and reaction liquid applied to the sheet S.

[0019] 1, a fixing module 4000 as a fixing system has a fixing belt unit 4100 as a fixing device. The fixing belt unit 4100 fixes ink onto the sheet S by passing the sheet S conveyed from the drying module 3000 between a heated upper belt unit and a heated lower belt unit.

[0020] The cooling module 5000 has a plurality of cooling sections 5001, which cool the high-temperature sheet S transported from the fixing module 4000. The cooling sections 5001, for example, use a fan to draw outside air into a cooling box to increase the pressure inside the cooling box, and then cool the sheet S by blowing air out of the cooling box through a nozzle due to the pressure onto the sheet S. The cooling sections 5001 are arranged on both sides of the transport path of the sheet S, and cool both sides of the sheet S.

[0021] The cooling module 5000 is provided with a transport path switching unit 5002. The transport path switching unit 5002 switches the transport path of the sheet S depending on whether the sheet S is transported to the reversing module 6000 or to a double-sided transport path for double-sided printing, in which images are formed on both sides of the sheet S.

[0022] The reversing module 6000 has a reversing section 6400. The reversing section 6400 reverses the sheet S being conveyed, changing the orientation of the sheet 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 sheet S conveyed from the reversing module 6000.

[0023] During double-sided printing, the sheet S is transported to a transport path below the cooling module 5000 by the transport path switching unit 5002. The sheet S then passes through a double-sided transport path including 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 transport section of the fixing module 4000 is provided with an inverting unit 4200 that inverts the sheet S. An image is formed with ink on the other side of the sheet S that has been returned to the print module 2000, and the sheet S is then ejected from the drying module 3000 through the inverting module 6000 and onto the stacking module 7000.

[0024] [Drying module] Next, the drying module 3000 will be described in detail with reference to Figures 2 and 3. The drying module 3000 has a decoupling unit 40, a drying belt unit 5, and a hot air blowing unit 8. These are collectively referred to as the drying function unit 300. The drying function unit 300 is arranged above the drying module 3000, and has a linear sheet transport path 1 for receiving the sheet S discharged from the print module 2000, drying the sheet S, and then delivering the sheet S to the fixing module 4000. With regard to the sheet transport direction in this sheet transport path 1, the upstream and downstream portions of the drying function unit 300 have different functions.

[0025] A decoupling section 40 is disposed upstream of the drying function section 300. The decoupling section 40 includes a decoupling belt unit 2 and a cold air blowing unit 3. The cold air blowing unit 3 is disposed vertically above the decoupling belt unit 2, which transports the sheet S in a substantially horizontal direction. The decoupling belt unit 2 includes a rotating endless belt 2a. The cold air blowing unit 3 blows cold air (air) from above the decoupling belt unit 2, thereby pressing the sheet S against the belt 2a and transporting the sheet S. The decoupling belt unit 2 has a plurality of holes for allowing the air blown from the cold air blowing unit 3 to escape from the blowing surface to the side opposite the belt. Note that, hereinafter, air that is not heated by a heater or the like is also referred to as "cold air."

[0026] When the leading edge of the sheet S reaches the decoupling belt unit 2 of the drying module 3000, the trailing edge of the sheet S is still on the print belt unit 2010 of the print module 2000. The print belt unit 2010 has an endless print belt 4 that sucks and transports the sheet. An image is formed on the sheet S on the print belt 4, and the sheet S is sucked and transported on the print belt 4. To prevent disturbance to this image formation process, the force pressing the sheet S against the belt 2a is weaker than the suction force of the print belt 4, and the belt 2a is driven at a slightly faster speed than the print belt 4. In other words, while the trailing edge of the sheet S is on the print belt 4, the sheet S is always sliding against the belt 2a.

[0027] On the other hand, the moment the trailing edge of the sheet S leaves the area of ​​the print belt 4, the transport of the sheet S becomes dependent on the belt 2a. At this time, it is necessary to control the air blowing force of the cool air blowing unit 3 so that the sheet S does not slip due to transport resistance. Therefore, the speed of the air blown from the cool air blowing unit 3 onto the sheet S transported on the belt 2a is controlled to a predetermined pressure using a pressure sensor (not shown) provided inside the cool air blowing unit 3 and an intake fan (not shown) provided in the intake section. The cool air blowing unit 3 has a blowing surface with many blowing holes for passing air so that a uniform pressing force can be applied to the sheet S.

[0028] [Drying section] Next, the drying section 6 will be described with reference to FIG. 2. The drying section 6 is disposed downstream of the drying function section 300. The drying section 6 includes a drying belt unit 5 and a hot air blowing unit 8. The hot air blowing unit 8 is disposed vertically above the drying belt unit 5, which is an example of a sheet conveying section and conveys the sheet S bearing an ink image in a substantially horizontal direction. In the drying section 6, the drying belt unit 5 sucks the sheet S to adhere it to the drying belt 7, while the hot air blowing unit 8 blows hot air from above in the vertical direction to dry the sheet S, thereby conveying the sheet while suppressing waviness known as cockling. Note that in this embodiment, the drying method involves blowing hot air and heating the belt, but is not limited to this. For example, in addition to blowing hot air, a method of irradiating the surface of the sheet S with electromagnetic waves (such as ultraviolet rays or infrared rays) or a conductive heat transfer method through contact with a heating element may be combined.

[0029] [Drying belt unit] Next, the drying belt unit 5 will be described with reference to Fig. 2. The drying belt unit 5 has a drying belt 7, which is a rotating endless belt, a plurality of tension rollers 9 around which the drying belt 7 is tensioned, and a belt heater 9a for heating the drying belt 7, and conveys a sheet while heating it with the drying belt 7. The belt heater 9a is a halogen heater disposed inside one of the tension rollers 9, and heats the drying belt 7 via the tension roller 9. In this embodiment, of the pair of tension rollers 9 that tension the surface facing the hot air blowing unit 8, the belt heater 9a is disposed inside the tension roller 9 on the upstream side in the sheet conveying direction.

[0030] Furthermore, the drying belt unit 5 has a suction box (not shown) arranged on the inner periphery of the drying belt 7, and a suction fan (not shown) connected to the suction box. The drying belt 7 has a plurality of suction holes (not shown) through which air is sucked by the suction fan. The suction box has suction ports formed on the surface facing the drying belt 7. The suction fan sucks air through the suction box, so that the air is sucked through the plurality of suction holes in the drying belt 7, and the sheet S is adsorbed to the surface of the drying belt 7.

[0031] In order to quickly dry the sheet S, the surface temperature of the drying belt 7 is adjusted to a predetermined temperature by controlling the belt heater 9a disposed inside the tension roller 9 based on the temperature detected by a temperature sensor (not shown) disposed inside the drying belt unit 5. In this way, the sheet S transported by the drying belt 7 is heated.

[0032] To fix the sheet S on the drying belt 7, the suction pressure on the upper surface of the drying belt 7 is adjusted to a predetermined pressure by controlling the suction fan based on the pressure detected by a pressure sensor (not shown) installed inside the suction box 5a. The distance from the suction end position of the print belt 4 to the suction start position of the drying belt 7 is set to be longer than the maximum sheet length.

[0033] [Hot air blowing unit] Next, the hot air blowing unit 8 will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, in this embodiment, the hot air blowing unit 8 is configured with, for example, six units having similar configurations lined up in the sheet conveying direction. Each unit can blow hot air onto the sheet independently of the other units. The housing of the drying module 3000 is provided with an air intake port (not shown) for drawing in air from outside the inkjet recording apparatus 100, and an exhaust port (not shown) for exhausting air inside the drying section 6 to the outside of the apparatus. The hot air blowing unit 8 heats the air drawn in through the air intake port, blows it onto the sheet, and exhausts it from the exhaust port.

[0034] In this embodiment, each of the three hot air blowing units 8 on the upstream side in the sheet conveying direction is referred to as a first hot air blowing unit 8a, and each of the three hot air blowing units 8 on the downstream side is referred to as a second hot air blowing unit 8b. That is, the first hot air blowing unit 8a and the second hot air blowing unit 8b each consist of a plurality of units lined up in the sheet conveying direction. The first hot air blowing unit 8a is an example of a first unit, and the second hot air blowing unit 8b is an example of a second unit. As described above, the first hot air blowing unit 8a and the second hot air blowing unit 8b have the same configuration, so the following description will representatively focus on the first hot air blowing unit 8a. Furthermore, all of the hot air blowing units 8 are supplied with power from the same commercial AC power supply 51 (see FIG. 4).

[0035] Fig. 3 is a configuration diagram of the first hot air blowing unit 8a. As shown in Fig. 3, the first hot air blowing unit 8a includes a first blower fan 13a, a first blower duct 14a, a first heater 15a, a first thermostat 16a, a first temperature sensor 17a, and a first pressure sensor 18a. The first blower duct 14a is formed in a generally U-shape and includes an upper duct 21a disposed horizontally at the top and a lower duct 22a curved downward from the upper duct 21a and disposed horizontally below the upper duct 21a, facing the drying belt 7. The arrows inside the first blower duct 14a indicate the air flow direction.

[0036] The first blower fan 13a is provided at the end of the upper duct 21a of the first blower duct 14a, and draws air from the outside of the drying module 3000 through an air intake (not shown). That is, the first blower fan 13a is provided at the upstream end of the first blower duct 14a in the gas flow direction. In this embodiment, the first blower fan 13a is an axial flow fan. However, the first blower fan 13a is not limited to an axial flow fan, and may be a fan of another configuration, such as a sirocco fan.

[0037] The first heater 15a is located in the upper duct 21a of the first blower duct 14a, downstream of and adjacent to the first blower fan 13a in the air flow direction. The first heater 15a is connected to a control board 50 (see FIG. 4) via a first heater cable 23a. The first heater 15a generates heat using power supplied from a commercial AC power supply 51 (see FIG. 4). The first heater 15a is a two-wire sheathed heater, and its power specifications are, for example, 1200 W / 200 V. However, the power specifications are not limited to this, and the number of wires may be one or three or more. Furthermore, from the standpoints of safety and energy efficiency, heating using, for example, an electric heating wire or an infrared heater is preferable for the first heater 15a, and a halogen heater, for example, may be used. However, the first heater 15a is not limited to these, and a wide variety of heaters that generate heat when supplied with power may be used.

[0038] The first thermostatic switch 16a is a switch that automatically turns off when the first heater 15a abnormally rises in temperature. The first thermostatic switch 16a is connected to the control board 50 (see FIG. 4) via a first switch cable 24a. The first temperature sensor 17a is provided to detect the temperature of the air blown onto the seat S and is provided in the upper duct 21a of the first air duct 14a, downstream of and spaced apart from the first heater 15a in the air flow direction. That is, the first temperature sensor 17a is an example of a first detection unit and detects the temperature of the air inside the first air duct 14a. The first temperature sensor 17a is connected to the control board 50 (see FIG. 4) via a first sensor cable 25a. The first pressure sensor 18a is provided in the lower duct 22a of the first air duct 14a and detects the pressure of the air inside the first air duct 14a.

[0039] The surface of the lower duct 22a facing the sheet S is a warm air blowing surface provided with a large number of blowing holes for passing air so as to uniformly dry the sheet S, and multiple first warm air blowing holes 10a are formed therein. The first warm air blowing holes 10a blow air sucked in from the air intake port toward the sheet S being transported by the drying belt unit 5.

[0040] Meanwhile, the temperature of the hot air in the first hot air blowing unit 8a is controlled to a predetermined temperature using a first temperature sensor 17a and a first heater 15a provided inside the unit. Also, the speed of the air blowing from the first hot air blowing hole 10a of the first hot air blowing unit 8a is controlled to a predetermined pressure using a first pressure sensor 18a and a first blower fan 13a provided inside the unit. The first hot air blowing unit 8a dries the ink on the sheet S with this configuration.

[0041] In the first air duct 14a, except for the first air fan 13a (input) and the first hot air blowing hole 10a (output), the first air duct 21a and the lower duct 22a form a continuous closed path to prevent air from leaking. The upper surface of the upper duct 21a forms the first top plate 20a. In this embodiment, the first heater cable 23a, the first switch cable 24a, and the first sensor cable 25a are provided above the first top plate 20a. Therefore, compared to wiring inside the upper duct 21a, it is possible to prevent deterioration in efficiency due to airflow turbulence and pressure loss caused by cables obstructing the air path.

[0042] In this embodiment, the first heater 15a is controlled based on the detection results from the first temperature sensor 17a to maintain the air temperature within the first air duct 14a at a maximum of 120°C. Meanwhile, unheated air drawn in from the outside circulates above the first top panel 20a, where the air temperature is lower than that within the upper duct 21a. Therefore, the heat resistance temperatures of the first heater cable 23a, first switch cable 24a, and first sensor cable 25a do not need to be set to 120°C, the maximum temperature within the first air duct 14a, and cables with lower heat resistance can be used. In other words, the first heater cable 23a, first switch cable 24a, and first sensor cable 25a can be cables with a heat resistance of 80°C, which is lower than the maximum temperature within the first air duct 14a. This reduces costs compared to using cables with higher heat resistance.

[0043] Thus, the first warm air blowing unit 8a includes a first blower fan 13a that blows air, a first blower duct 14a that guides the air blown by the first blower fan 13a, and a first heater 15a that heats the air inside the first blower duct 14a. The first warm air blowing unit 8a also includes a first temperature sensor 17a that detects the temperature of the air inside the first blower duct 14a. Similarly, as shown in FIG. 4, the second warm air blowing unit 8b includes a second blower fan 13b, a second blower duct 14b that guides the air blown by the second blower fan 13b, and a second heater 15b that heats the air inside the second blower duct 14b. The second heater 15b is connected to the control board 50 via a second heater cable 23b. The second hot air blowing unit 8b also has a second temperature sensor 17b (second detection unit) that detects the temperature of the air inside the second blower duct 14b. The second temperature sensor 17b is connected to the control board 50 via a second sensor cable 25b.

[0044] Here, the first hot air blowing unit 8a and the second hot air blowing unit 8b have the same configuration, and therefore the first heater 15a and the second heater 15b are heaters that have the same heat value relative to the power supplied from the commercial AC power supply 51. This makes it possible to reduce the complexity of the control pattern compared to when heaters with different heat values ​​are used.

[0045] [Control system] Next, the control system of the hot air blowing unit 8 of this embodiment will be described with reference to Fig. 4. Fig. 4 is a block diagram showing a control board 50 that controls the hot air blowing unit 8. The control board 50 has a CPU 41, which is an example of a control unit, a memory 42, a voltage detection unit 43, a first drive circuit 44a, and a second drive circuit 44b. The CPU 41 controls the supply of power to the first heater 15a and the second heater 15b in accordance with a control program stored in the ROM area of ​​the memory 42. The memory 42 can include, for example, a non-volatile memory (ROM), a non-volatile memory (RAM), a solid state drive (SSD), and a hard disk drive (HDD).

[0046] AC current supplied from a commercial AC power supply 51, such as a commercial power source, passes through a voltage detection unit 43 and is supplied to the first heater 15a and the second heater 15b via a first drive circuit 44a or a second drive circuit 44b, respectively. The voltage detection unit 43 detects the zero potential of the commercial AC power supply 51 and sends it to the CPU 41. The first drive circuit 44a and the second drive circuit 44b are composed of switches such as relays and triacs. Note that the switching elements used in the first drive circuit 44a and the second drive circuit 44b are not limited to relays and triacs, and may also be thyristors, transistors, IGBTs (insulated gate bipolar transistors), etc.

[0047] The first drive circuit 44a is synchronized with the zero potential of the commercial AC power supply 51 detected by the voltage detection unit 43, i.e., it switches on and off based on the zero potential, and supplies power to the first heater 15a. The first drive circuit 44a switches on and off periodically, and a control pattern is determined in advance based on the duty ratio of the power supplied to the first heater 15a. The control pattern at that time is stored in the memory 41 as a table or the like. The control pattern is switched based on temperature information of the first heater 15a detected by the first temperature sensor 17a.

[0048] Similarly, the second drive circuit 44b is synchronized with the zero potential of the commercial AC power supply 51 detected by the voltage detection unit 43, i.e., it switches on and off based on the zero potential, and supplies power to the second heater 15b. The second drive circuit 44b switches on and off periodically, and a control pattern is determined in advance based on the duty ratio of the power supplied to the second heater 15b. The control pattern at that time is stored in the memory 41 as a table or the like. The control pattern is switched based on temperature information of the second heater 15b detected by the second temperature sensor 17b.

[0049] [Comparative Example] Next, a comparative example of the control pattern for turning on and off the first heater 15a and the second heater 15b will be described using FIGS. 5(a) and 5(b). Here, the control patterns for the first heater 15a and the second heater 15b are independently controlled by the CPU 41, and the control patterns stored in the memory 42 are patterns for every 10 seconds. As shown in FIG. 5(a), when the on states of the first heater 15a and the second heater 15b are not overlapping, a voltage fluctuation occurs in the commercial AC power supply 51 every time the first heater 15a and the second heater 15b are driven. Therefore, a voltage fluctuation (load fluctuation) in the commercial AC power supply 51 occurs four times in 10 seconds, or 24 times in one minute. As shown in FIG. 5(b), when the on states of the first heater 15a and the second heater 15b are overlapping but not overlapping, a voltage fluctuation occurs in the commercial AC power supply 51 every time the first heater 15a and the second heater 15b are driven. Therefore, voltage fluctuations (load fluctuations) on the commercial AC power supply 51 occur four times in 10 seconds, and 24 times in one minute.

[0050] [Control pattern of this embodiment] Next, the control pattern for turning on and off the first heater 15a and the second heater 15b in this embodiment will be described with reference to FIG. 6. As in the comparative example, the control pattern stored in the memory 42 is periodic, occurring every 10 seconds, and is based on the zero potential detected by the voltage detection unit 43. The power supply pattern for the first heater 15a is a control pattern in which the commercial AC power supply 51 continuously supplies power. The power supply pattern for the second heater 15b is a control pattern in which the zero potential detected by the voltage detection unit 43 is synchronized with the on / off timing of the first heater 15a. Furthermore, the control pattern is such that while power is being supplied to the first heater 15a, power is not supplied to the second heater 15b, and power is supplied to the second heater 15b as soon as the first heater 15a stops.

[0051] Here, the CPU 41 can execute a control pattern that alternates between a first state and a second state. In this embodiment, the pattern is such that the first state and the second state are executed once each within 10 seconds. The first state includes a first heater-on state and a second heater-on state. The first heater-on state is a state in which power is supplied to the first heater 15a but not to the second heater 15b. The second heater-on state is a state in which power is supplied to the second heater 15b but not to the first heater 15a. In the first state, the CPU 41 transitions from the first heater-on state to the second heater-on state by stopping the power supply to the first heater 15a and simultaneously starting the power supply to the second heater 15b. The second state is a state in which power is not supplied to either the first heater 15a or the second heater 15b.

[0052] In the first state, the CPU 41 starts the power supply to the first heater 15a, then stops the power supply to the first heater 15a and simultaneously starts the power supply to the second heater 15b, and then stops the power supply to the second heater 15b, thereby transitioning to the second state. That is, by simultaneously stopping the power supply to the first heater 15a and starting the power supply to the second heater 15b, it is possible to prevent voltage fluctuations caused by stopping the power supply to the first heater 15a and starting the power supply to the second heater 15b. By creating such a control pattern, power is supplied constantly from the commercial AC power supply 51, and voltage fluctuations can be reduced to two in 10 seconds and to 12 in 1 minute.

[0053] FIG. 7 shows the allowable converted actual current value of voltage fluctuations for the commercial AC power supply 51. The horizontal axis represents the number of voltage fluctuations per minute for the commercial AC power supply 51. The vertical axis represents the effective value of the current flowing through the heater. The solid line in the figure represents a curve where the voltage flicker value is 1.0, and the dashed line represents a curve where the voltage flicker value is 0.8. When 1000 W / 200 V is selected as the specifications for the first heater 15a and the second heater 15b, if the power supply patterns shown in FIGS. 5(a) and 5(b) are implemented, the number of voltage fluctuations per minute is 24, resulting in a voltage flicker value of 1.0. On the other hand, if the power supply pattern of this embodiment shown in FIG. 6 is implemented, the number of voltage fluctuations per minute is 12, resulting in a voltage flicker value of 0.8. Therefore, according to this embodiment, the voltage flicker value can be improved by 20% compared to the comparative example.

[0054] 8 is a flowchart showing a control process procedure in which the CPU 41 mounted on the control board 50 controls the supply of power to the first heater 15a and the second heater 15b. When the process starts, the CPU 41 determines whether or not the voltage detection unit 43 has detected zero potential information (S1). If the CPU 41 determines that the voltage detection unit 43 has not detected zero potential information (S1; NO), the CPU 41 again determines whether or not the voltage detection unit 43 has detected zero potential information (S1). If the CPU 41 determines that the voltage detection unit 43 has detected zero potential information (S1; YES), the CPU 41 sets the duty ratio of the power to be supplied to the first heater 15a and the second heater 15b (S2).

[0055] The CPU 41 selects a power supply pattern corresponding to the set power duty ratio by referring to the table in the memory 42 (S3). Here, the power supply patterns stored in the memory 42 are assumed to be periodic power supply patterns for each heater every 10 seconds, as shown in FIG. 6. The power supply pattern for the first heater 15a is a pattern in which the commercial AC power supply 51 continuously supplies power at a predetermined duty ratio. The power supply pattern for the second heater 15b is a pattern in which power is not supplied to the second heater 15b while power is being supplied to the first heater 15a. The zero potential detected by the voltage detection unit 43 is then used to synchronize the on / off timing of the first heater 15a and to continuously supply power from the commercial AC power supply 51 at a predetermined duty ratio.

[0056] The CPU 41 simultaneously switches and supplies power to the first heater 15a and the second heater 15b from the commercial AC power supply 51 in the power supply pattern selected from the memory 42, with the zero potential detected by the voltage detection unit 43 as a reference, and turns on each heater (S4). The CPU 41 monitors and detects the temperatures of each heater using the first temperature sensor 17a and the second temperature sensor 17b (S5).

[0057] The CPU 41 determines whether the temperatures detected by the first temperature sensor 17a and the second temperature sensor 17b have reached or exceeded the temperatures preset in the memory 42 (S6). If the CPU 41 determines that the detected temperatures have not reached or exceeded the temperatures preset in the memory 42 (S6; NO), it makes a determination again (S6). If the CPU 41 determines that the detected temperatures have reached or exceeded the temperatures preset in the memory 42 (S6; YES), it determines whether the duty ratio of the power supplied to each heater needs to be changed (S7).

[0058] When the CPU 41 determines that the duty ratio of the power supplied to each heater needs to be changed (S7; YES), it changes the duty ratio of the power supplied to each heater (S8). Here, the CPU 41 calculates how much higher or lower the detected temperature is compared to a preset target temperature, and changes the duty ratio to an appropriate value to achieve the target temperature. Since the duty ratio is changed based on the detection results of the first temperature sensor 17a and the second temperature sensor 17b, the CPU 41 controls the time ratio between the first state and the second state based on the detection results of the first temperature sensor 17a and the second temperature sensor 17b.

[0059] After changing the duty ratio of the power supplied to each heater in S8, or if the CPU 41 determines that the duty ratio of the power supplied to each heater does not need to be changed (S7; NO), it determines whether or not to stop each heater (S9). If the CPU 41 determines not to stop each heater (S9; NO), it determines whether or not the temperatures detected by the first temperature sensor 17a and the second temperature sensor 17b have reached or exceeded a temperature preset in the memory 42 (S6). If the CPU 41 determines to stop each heater (S9; YES), it stops each heater (S10).

[0060] As described above, the drying module 3000 of this embodiment can execute a control pattern that alternates between the first state and the second state, as shown in FIG. 6. In the first state, the CPU 41 transitions from the first heater-on state to the second heater-on state by stopping the power supply to the first heater 15a and simultaneously starting the power supply to the second heater 15b. This prevents voltage fluctuations due to the stopping of the power supply to the first heater 15a and the starting of the power supply to the second heater 15b. This allows a constant supply of power from the commercial AC power supply 51, limiting voltage fluctuations to two per 10 seconds, a reduction in the number of fluctuations compared to the case shown in FIG. 5(a), thereby suppressing voltage flicker.

[0061] In the present embodiment, the three hot air blowing units 8 on the upstream side in the sheet conveying direction are designated as first hot air blowing units 8a, and the three hot air blowing units 8 on the downstream side are designated as second hot air blowing units 8b. However, this is not limiting. For example, the three hot air blowing units 8 on the downstream side in the sheet conveying direction may be designated as first hot air blowing units 8a, and the three hot air blowing units 8 on the upstream side may be designated as second hot air blowing units 8b. Alternatively, the first hot air blowing units 8a and the second hot air blowing units 8b may be arranged alternately. In addition, in the present embodiment, the six hot air blowing units 8 are provided, but this is not limiting. For example, if an even number of hot air blowing units 8, such as four or eight, are provided, the first hot air blowing units 8a and the second hot air blowing units 8b may be divided into equal numbers, thereby making the power fluctuations of the first hot air blowing units 8a and the second hot air blowing units 8b equal.

[0062] <Second embodiment> Next, a second embodiment of the present invention will be described in detail with reference to Figures 9(a) and (b). In this embodiment, the configuration of the hot air blowing unit 8A is different from that of the first embodiment in that it has a first hot air blowing unit 8Aa, a second hot air blowing unit 8Ab, and a third hot air blowing unit 8Ac. However, other configurations are the same as those of the first embodiment, so the same reference numerals are used and detailed description will be omitted.

[0063] In this embodiment, as shown in FIG. 9(a), the first hot air blowing units 8Aa are two hot air blowing units 8A located upstream in the sheet conveying direction, and the second hot air blowing units 8Ab are two hot air blowing units 8A located downstream of the first hot air blowing units 8Aa. Furthermore, the third hot air blowing units 8Ac are two hot air blowing units 8A located downstream of the second hot air blowing unit 8Aa in the sheet conveying direction. That is, the first hot air blowing units 8Aa, the second hot air blowing units 8Ab, and the third hot air blowing units 8Ac each consist of a plurality of units lined up in the sheet conveying direction. The first hot air blowing units 8Aa are an example of a first unit, the second hot air blowing units 8Ab are an example of a second unit, and the third hot air blowing units 8Ac are an example of a third unit. The first hot air blowing unit 8Aa, the second hot air blowing unit 8Ab, and the third hot air blowing unit 8Ac have the same configuration as the first hot air blowing unit 8a shown in the first embodiment.

[0064] The third hot air blowing unit 8Ac has a third blower fan, a third blower duct that guides the air blown by the third blower fan, and a third heater that heats the air inside the third blower duct. The third heater is connected to the control board 50 via a third heater cable. The third hot air blowing unit 8Ac also has a third temperature sensor that detects the temperature of the air inside the third blower duct. The third temperature sensor is connected to the control board 50 via a third sensor cable.

[0065] The control patterns for turning on and off the first heater 15a, second heater 15b, and third heater in this embodiment will be described with reference to FIG. 9B. The control patterns stored in the memory 42 are periodically set every 10 seconds, based on the zero potential detected by the voltage detection unit 43. The power supply pattern for the first heater 15a is a control pattern in which the commercial AC power supply 51 continuously supplies power. The power supply pattern for the second heater 15b is a control pattern in which the zero potential detected by the voltage detection unit 43 is synchronized with the on / off timing of the first heater 15a. The power supply pattern for the third heater is a control pattern in which the zero potential detected by the voltage detection unit 43 is synchronized with the on / off timing of the second heater 15b. Furthermore, while power is being supplied to the first heater 15a, power is not supplied to the second heater 15b or the third heater, and power is supplied to the second heater 15b as soon as the first heater 15a is stopped. Also, a control pattern is adopted in which power is not supplied to the first heater 15a and the third heater while power is being supplied to the second heater 15b, and power is supplied to the third heater as soon as the second heater 15b stops.

[0066] In this embodiment, the CPU 41 can execute a control pattern in which the third state and the fourth state are repeated. In this embodiment, the third state and the fourth state are executed once each within 10 seconds. The third state includes a first heater-on state, a second heater-on state, and a third heater-on state. The first heater-on state here refers to a state in which power is supplied to the first heater 15a, but power is not supplied to the second heater 15b and the third heater. The second heater-on state refers to a state in which power is supplied to the second heater 15b, but power is not supplied to the first heater 15a and the third heater. The third heater-on state refers to a state in which power is supplied to the third heater, but power is not supplied to the first heater 15a and the second heater 15b. In the third state, the CPU 41 transitions from the first heater-on state to the second heater-on state by stopping the power supply to the first heater 15a and simultaneously starting the power supply to the second heater 15b. Furthermore, the CPU 41 transitions to the third heater-on state by stopping the power supply to the second heater 15b and simultaneously starting the power supply to the third heater. The fourth state is a state in which no power is supplied to any of the first heater 15a, the second heater 15b, and the third heater.

[0067] In the third state, the CPU 41 starts the power supply to the first heater 15a, then stops the power supply to the first heater 15a and starts the power supply to the second heater 15b at the same time. Then, it stops the power supply to the second heater 15b and starts the power supply to the third heater at the same time, and transitions to the fourth state by stopping the power supply to the third heater. That is, by simultaneously stopping the power supply to the first heater 15a and starting the power supply to the second heater 15b, and simultaneously stopping the power supply to the second heater 15b and starting the power supply to the third heater, it is possible to prevent voltage fluctuations due to the stopping of the power supply to the first heater 15a, the starting of the power supply to the second heater 15b, the stopping of the power supply to the second heater 15b, and the starting of the power supply to the third heater. By creating such a control pattern, a constant power is supplied from commercial AC power supply 51, and voltage fluctuations can be reduced to two in 10 seconds, and to 12 in one minute.

[0068] As described above, the drying module 3000 of this embodiment can execute a control pattern that repeatedly switches between the third and fourth states, as shown in FIG. 9(b). In the third state, the CPU 41 transitions from the first heater-on state to the second heater-on state by stopping the power supply to the first heater 15a and simultaneously starting the power supply to the second heater 15b. Furthermore, the CPU 41 transitions from the second heater-on state to the third heater-on state by stopping the power supply to the second heater 15b and simultaneously starting the power supply to the third heater. This reduces voltage fluctuations due to the stopping of the power supply to the first heater 15a, the starting of the power supply to the second heater 15b, the starting of the power supply to the second heater 15b, and the starting of the power supply to the third heater. Therefore, this embodiment also reduces the number of load fluctuations, thereby suppressing the occurrence of voltage flicker.

[0069] In each of the above-described embodiments, the hot air blowing units 8, 8A are divided into two or three units and switched on and off simultaneously, but this is not limited to this, and the units may be divided into four or more units and switched on and off simultaneously. [Explanation of symbols]

[0070] 5...Drying belt unit (sheet conveying section), 7...Drying belt (belt), 8a...First warm air blowing unit (first unit), 8b...Second warm air blowing unit (second unit), 8Aa...First warm air blowing unit (first unit), 8Ab...Second warm air blowing unit (second unit), 8Ac...Third warm air blowing unit (third unit), 9...Tension roller, 9a...Belt heater, 13a...First blower fan (first fan), 13b...Second blower Fan (second fan), 14a...first air duct (first duct), 14b...second air duct (second duct), 15a...first heater (first heating element), 15b...second heater (second heating element), 17a...first temperature sensor (first detection unit), 17b...second temperature sensor (second detection unit), 41...CPU (control unit), 100...inkjet recording device, 2000...print module (image forming unit), 3000...drying module (air blowing device)

Claims

1. an image forming unit that forms an ink image on a sheet; a sheet conveying section that conveys a sheet bearing an ink image; an air blowing device that blows air onto the sheet being conveyed to the sheet conveying section, The air blowing device is a first unit including a first fan that blows air, a first duct that guides the air blown by the first fan, and a first heating element that generates heat by power supplied from an AC power source to heat the air inside the first duct; a second unit including a second fan that blows air, a second duct that guides the air blown by the second fan, and a second heating element that generates heat by electric power supplied from the AC power supply to heat the air inside the second duct; a control unit that controls the supply of power to the first heating element and the second heating element, The control unit is capable of executing a control pattern that repeats a first state in which a state in which power is supplied to the first heating element and power is not supplied to the second heating element is switched to a state in which power is supplied to the second heating element and power is not supplied to the first heating element by simultaneously stopping power supply to the first heating element and starting power supply to the second heating element, and a second state in which power is not supplied to both the first heating element and the second heating element. An inkjet recording apparatus characterized by:

2. the control unit starts supplying power to the first heating element in the first state, then stops supplying power to the first heating element and starts supplying power to the second heating element at the same time, and then stops supplying power to the second heating element, thereby transitioning to the second state.

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

3. the first unit has a first detector that detects the temperature of air inside the first duct, the second unit has a second detection unit that detects the temperature of air inside the second duct, the control unit controls a time ratio between the first state and the second state based on the detection results of the first detection unit and the second detection unit.

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

4. the first heating element and the second heating element are heaters that generate the same amount of heat in response to the power supplied from the AC power source; 2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

5. the first unit and the second unit each include a plurality of units arranged in a sheet conveying direction; 2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

6. the sheet conveying unit includes a rotating endless belt, a plurality of tension rollers that tension the belt, and a belt heater that heats the belt, and conveys the sheet while heating it with the belt; 2. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is a recording medium.

7. The first heating element and the second heating element are sheath heaters.

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

8. an image forming unit that forms an ink image on a sheet; a sheet conveying section that conveys a sheet bearing an ink image; an air blowing device that blows air onto the sheet being conveyed to the sheet conveying section, The air blowing device is a first unit including a first fan that blows air, a first duct that guides the air blown by the first fan, and a first heating element that generates heat by power supplied from an AC power source to heat the air inside the first duct; a second unit including a second fan that blows air, a second duct that guides the air blown by the second fan, and a second heating element that generates heat by electric power supplied from the AC power supply to heat the air inside the second duct; a third unit including a third fan that blows air, a third duct that guides the air blown by the third fan, and a third heating element that generates heat by electric power supplied from the AC power supply and heats the air inside the third duct; a control unit that controls the supply of power to the first heating element, the second heating element, and the third heating element, The control unit is capable of executing a control pattern that repeats a third state in which power is supplied to the first heating element and power is not supplied to the second heating element and the third heating element, transitioning from a state in which power supply to the first heating element is supplied and power supply to the second heating element is started simultaneously with stopping power supply to the first heating element, power is supplied to the second heating element and power is not supplied to the first heating element and the third heating element, transitioning to a state in which power supply to the second heating element is supplied and power is not supplied to the first heating element and the third heating element, transitioning to a state in which power supply to the second heating element is supplied and power supply to the third heating element is started simultaneously with stopping power supply to the second heating element, power is supplied to the third heating element and power is not supplied to the first heating element and the second heating element, and a fourth state in which power is not supplied to any of the first heating element, the second heating element and the third heating element. An inkjet recording apparatus characterized by:

9. In the third state, the control unit starts supplying power to the first heating element, then stops supplying power to the first heating element and starts supplying power to the second heating element at the same time, then stops supplying power to the second heating element and starts supplying power to the third heating element at the same time, and transitions to the fourth state by stopping the supply of power to the third heating element.

9. The inkjet recording apparatus according to claim 8,

Images