Liquid application system and exhaust volume control method

Abstract

To reduce the energy loss by controlling an exhaust volume.SOLUTION: A liquid application system includes liquid application means 3 to apply a liquid to a sheet S, a heater 4 to heat the sheet S to which the liquid is applied, exhauster means 5 to exhaust air from the heater 4, and a controller 8 to control the exhauster means 5. The controller 8 controls an exhaust volume by the exhauster means 5 based on an amount of vapor from the sheet S in the heater 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid application system and an exhaust gas amount control method.

Background Art

[0002] As an example of a liquid application device, an image forming device that forms an image on a sheet by applying ink to the sheet is known.

[0003] Some such image forming devices are provided with a drying device for drying the sheet to which ink has been applied.

[0004] For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-89648), when drying a sheet to which ink has been applied, a drying control system is proposed that determines a target value of drying conditions according to the amount of ink applied to the sheet and controls a drying unit based on the determined target value.

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, although control of the drying unit based on the ink amount is proposed, the exhaust gas amount when discharging vapor containing moisture or solvent vaporized from the sheet by the drying process to the outside of the device has not been studied.

[0006] Therefore, an object of the present invention is to control the exhaust gas amount.

Means for Solving the Problems

[0007] To solve the above problems, the present invention provides a liquid application system including: a liquid application means for applying a liquid to a sheet; a heating device for heating the sheet to which the liquid has been applied; an exhaust means for exhausting air in the heating device; and a control unit for controlling the exhaust means, wherein the control unit controls the exhaust gas amount of the exhaust means based on the amount of vapor generated from the sheet in the heating device.

Advantages of the Invention

[0008] According to the present invention, the displacement can be controlled.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, the present invention will be described based on the accompanying drawings. In each of the drawings for explaining the present invention, components having the same function or shape, such as members and components, are given the same reference numerals as much as possible for discrimination, and the description thereof will be omitted after being explained once.

[0011] First, the configuration of an image forming system, which is an example of a liquid application system according to the present invention, will be described.

[0012] **Configuration of Image Forming System** FIG. 1 is a schematic configuration diagram of an image forming system 100 according to a first embodiment of the present invention.

[0013] As shown in FIG. 1, the image forming system 100 includes a sheet supply unit 1, a conveyance unit 2, a liquid application unit 3, a heating device 4, an exhaust unit 5, an air supply unit 6, a sheet collection unit 7, a control unit 8, and the like. In the first embodiment of the present invention, the liquid application unit 3, the heating device 4, the exhaust unit 5, and the air supply unit 6 are housed in a single housing 250, and together constitute an image forming apparatus 200. Note that the liquid application unit 3, the heating device 4, the exhaust unit 5, and the air supply unit 6 are not limited to being housed in the same housing 250, and may be housed in individual housings.

[0014] The sheet supply unit 1 has a supply roller 11 around which a long sheet S is wound in a roll shape. When the supply roller 11 rotates in the direction of the arrow in FIG. 1, the sheet S is fed out from the supply roller 11 and supplied. The sheet S may be a sheet of a predetermined size that has been cut in advance. In that case, as the sheet supply unit 1, a feed roller that feeds out sheets of a predetermined size one by one is used.

[0015] The conveying means 2 has a pair of conveying rollers 12 that convey while sandwiching the sheet S. Further, the conveying means 2 may be, in addition to the pair of conveying rollers 12, a conveying belt or the like that conveys while adsorbing the sheet S.

[0016] The liquid applying means 3 has a plurality of liquid discharge portions 13 that discharge liquid onto the sheet S. The plurality of liquid discharge portions 13 are constituted by a plurality of liquid discharge heads that discharge liquids (inks) of mutually different colors such as black, cyan, magenta, and yellow. Further, the liquid discharge portion 13 may be an integrated (one) liquid discharge head that discharges liquids of different colors. The discharge method of the liquid discharge portion 13 is not particularly limited, and examples of the discharge method include, in addition to the on-demand method of discharging minute liquid droplets, the continuous method of continuously jetting the liquid. Further, in the on-demand method, examples of the drive source for discharging the liquid include the pressure application method using a piezoelectric element, the thermal method of discharging the liquid by the pressure generated by bubbles when the liquid is heated, and the electrostatic method using electrostatic force. The color of the liquid discharged from the liquid discharge portion 13 is not limited to black, cyan, magenta, and yellow, and can be arbitrarily selected. Further, in FIG. 1, below each liquid discharge portion 13, a conveying guide member 14 that supports the conveyed sheet S is disposed.

[0017] The heating device 4 functions as a drying device that heats and dries the sheet S. Specifically, in the first embodiment of the present invention, the heating device 4 has heating means such as a heating roller 21 and a heating drum 22 that heat the sheet S. When the sheet S is carried into the heating device 4, the sheet S is heated and dried by coming into contact with the heating roller 21 and the heating drum 22. The heating means is not limited to contact-type heating means such as the heating roller 21 and the heating drum 22, and may be non-contact-type means such as those that heat the sheet S by radiating infrared rays or ultraviolet rays.

[0018] The exhaust means 5 is a means for exhausting the air inside the heating device 4. Specifically, the exhaust means 5 includes an exhaust fan 31 as an exhaust blowing means and an exhaust duct 32 that constitutes an exhaust passage. Instead of the exhaust fan 31, an exhaust blowing means such as a blower may be used. The exhaust duct 32 is provided so as to extend outward from the housing (outer casing) 20 of the heating device 4 to the outside of the housing (outer casing) 201 of the image forming apparatus 200. The exhaust fan 31 is connected to the exhaust duct 32. Here, the exhaust fan 31 is connected to the exhaust duct 32 outside the heating device 4 (housing 20) and inside the main body of the image forming apparatus (housing 250), but the exhaust fan 31 may be connected to the exhaust duct 32 outside the image forming apparatus 200 (housing 250).

[0019] The air supply means 6 is a means for supplying air into the heating device 4. Specifically, the air supply means 6 includes an air supply fan 41 as an air supply blowing means and an air supply duct 42 that constitutes an air supply passage. Instead of the air supply fan 41, an air supply blowing means such as a blower may be used. The air supply duct 42 is provided so as to extend outward from the housing 20 of the heating device 4 to the outside of the housing 250 of the image forming apparatus 200 in the same manner as the exhaust duct 32. Also, the air supply fan 41 is connected to the air supply duct 42 outside the heating device 4 (housing 20) and inside the main body of the image forming apparatus (housing 250), but the air supply fan 41 may be connected to the air supply duct 42 outside the image forming apparatus 200 (housing 250).

[0020] The sheet collecting means 7 has a collecting roller 15 that winds up and collects the sheet S. When the collecting roller 15 rotates in the direction of the arrow in FIG. 1, the sheet S is wound up in a roll shape by the collecting roller 15 and collected. Also, when the sheet S is a sheet of a predetermined size that has been cut in advance, as the sheet collecting means 7, a discharge tray or the like for stacking and placing the discharged sheets is used.

[0021] The control unit 8 is an information processing device that controls the overall operation of the image forming system 100. For example, the control unit 8 controls the sheet conveyance operation of the conveyance means 2, the liquid application operation of the liquid application means 3, the heating operation of the heating device 4, the exhaust operation of the exhaust means 5, and the like.

[0022] <Image forming operation> Subsequently, with reference to FIG. 1, the image forming operation of the image forming system 100 according to the first embodiment of the present invention will be described.

[0023] When the image forming operation is started, the supply roller 11 starts to rotate, and the sheet S is supplied from the supply roller 11.

[0024] The supplied sheet S is conveyed below each liquid discharge unit 13 by the conveyance roller pair 12, and liquid (ink) is discharged from each liquid discharge unit 13 onto the sheet S. Thereby, an image is formed on the sheet S.

[0025] Thereafter, the sheet S is conveyed to the heating device 4. In the heating device 4, the sheet S is heated by contacting the heating roller 21 and the heating drum 22 while being conveyed. Thereby, the liquid on the sheet S evaporates, and the drying of the sheet S is promoted.

[0026] Thereafter, the sheet S is carried out from the heating device 4 and conveyed to the recovery roller 15 by the conveyance roller pair 12. Then, the sheet S is wound up and recovered by the rotating recovery roller 15. Thereby, a series of image forming operations is completed.

[0027] <Configuration of the control unit> FIG. 2 is a block diagram showing the hardware configuration related to image formation in the control unit 8 according to the first embodiment of the present invention.

[0028] As shown in FIG. 2, the control unit 8 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, a NVRAM (Non-Volatile Random Access Memory) 504, an external device connection I / F 505, a network I / F 506, and a bus line 507.

[0029] The CPU 501 controls the overall operation of the image forming system 100. The ROM 502 stores programs and the like used for driving the CPU 501 such as the IPL. The RAM 503 is used as a work area for the CPU 501. The NVRAM 504 stores various data such as programs and holds the various data even while the power of the image forming apparatus 200 is turned off.

[0030] The external device connection I / F 505 is connected to a PC (Personal Computer) by a USB (Universal Serial Bus) cable or the like and communicates control signals and image data to be printed with the PC. The network I / F 506 is an interface for data communication using a communication network such as the Internet. The bus line 507 is an address bus, a data bus, or the like for electrically connecting each component such as the CPU 501.

[0031] Further, the control unit 8 includes a main scanning driver 508 and a liquid ejection driver 509. The main scanning driver 508 controls the movement of the carriage 600 on which the liquid ejection unit 13 is mounted in the main scanning direction (the width direction of the sheet). The liquid ejection driver 509 is a driver for controlling the drive of the liquid ejection unit 13. When the carriage 600 moves in the main scanning direction, the liquid ejection unit 13 moves in the main scanning direction (the width direction of the sheet) as the carriage 600 moves, and liquid is ejected from the liquid ejection unit 13 onto the intermittently conveyed sheet. Thereby, an image is formed on the sheet.

[0032] Further, the control unit 8 includes a sub-scanning driver 510. The sub-scanning driver 510 controls the conveyance of the sheet by the pair of conveyance rollers 12.

[0033] In addition, the liquid discharge unit 13 may be a serial type liquid discharge head that discharges liquid onto the sheet while moving in the width direction of the sheet, or a line type liquid discharge head that discharges liquid onto the sheet without moving. Further, the liquid discharge driver 509 may not be mounted on the carriage 600 and may be connected to the bus line outside the carriage 600. Further, the main scanning driver 508, the liquid discharge driver 509, and the sub-scanning driver 510 may each be functions realized by instructions of the CPU 501 according to a program.

[0034] <Configuration of Heating Device> FIG. 3 is a schematic configuration diagram of the heating device 4 according to the first embodiment of the present invention.

[0035] As shown in FIG. 3, the heating device 4 includes a heating roller 21, a heating drum 22, a guide roller 23, and an air blowing device 24 in addition to the heating roller 21.

[0036] The heating roller 21 and the heating drum 22 are cylindrical heating rotors having a heat source such as a halogen heater inside. In the first embodiment of the present invention, one heating drum 22 having a larger diameter than the heating roller 21 is disposed at the center of the heating device 4, and a plurality of heating rollers 21 are disposed around the heating drum 22. However, the arrangement and number of the heating roller 21 and the heating drum 22 are not limited to this and can be changed as appropriate.

[0037] The guide roller 23 is a cylindrical rotating body having no heat source inside and is a member that functions as a guiding means for guiding the sheet S. A plurality of guide rollers 23 are disposed inside the heating device 4. When the sheet S is wound around the guide roller 23, the heating roller 21, and the heating drum 22, a conveyance path for conveying the sheet S is configured.

[0038] The air blowing device 24 is a blowing means that blows air onto the sheet S to promote drying of the sheet S. A plurality of air blowing devices 24 are arranged so as to face the sheet S.

[0039] When the sheet S is carried into the heating device 4 having such a configuration, the sheet S is guided by the guide roller 23 and is draped over the outside of the heating roller 21. Here, the "outside" of the heating roller 21 means the side opposite to the side facing the heating drum 22 among the outer peripheral surfaces of the heating roller 21. Thereby, the surface of the sheet S opposite to the image forming surface comes into contact with the outside of the heating roller 21, and the sheet S is heated. Subsequently, the sheet S is wound around the heating drum 22. Thereafter, the sheet S is guided from the heating drum 22 to the heating roller 21 again and is conveyed while contacting the inside of the heating roller 21 (the side facing the heating drum 22).

[0040] In this way, after the sheet S comes into contact with the outside of the heating roller 21, it is wound around the heating drum 22, and then is conveyed while contacting the inside of the heating roller 21, whereby the surface of the sheet S opposite to the image forming surface is effectively heated. Also, air is blown onto the image forming surface of the sheet S from a plurality of air blowing devices 24, thereby promoting drying of the sheet S. As a result, the sheet S is dried and the sheet S is carried out of the heating device 4 by the guide roller 23.

[0041] <Measures against Condensation> Here, when the sheet S is heated by the heating device 4, the moisture or solvent contained in the liquid applied to the sheet S is released as vapor. Also, when the sheet S is heated, the moisture contained in the sheet S itself is also released as vapor. Such vapor exists in a gaseous state for a while, but then, if it is cooled in the heating device 4 and condenses, water droplets may adhere to the sheet S and cause image defects.

[0042] Therefore, in the first embodiment of the present invention, the exhaust means 5 in FIG. 1 is used to discharge the air in the heating device 4. As a result, the vapor generated from the sheet S is discharged outside the image forming apparatus 200 together with the air in the heating device 4, so that condensation in the heating device 4 can be suppressed. Note that the exhaust destination of the vapor may be outside the heating device 4, but for preventing image defects, it is preferably outside the image forming apparatus 200. Further, considering the influence on the environment when the solvent contained in the liquid vaporizes, the exhaust destination of the vapor may be outdoors.

[0043] <Configuration of Air Blowing Device> Subsequently, with reference to FIGS. 4 and 5, the configuration of the air blowing device 24 will be described.

[0044] FIG. 4 is a perspective view of the air blowing device 24 according to the first embodiment of the present invention as viewed from the sheet facing surface side facing the sheet. FIG. 5 is a perspective view of the air blowing device 24 according to the first embodiment of the present invention cut in the longitudinal direction. Since all the plurality of air blowing devices 24 have the same configuration, the configuration of one air blowing device 24 will be described based on FIGS. 4 and 5.

[0045] As shown in FIG. 4, the air blowing device 24 has a housing portion 24a having an air flow path therein, and an air outlet 24b and an air inlet 24c provided on the sheet facing surface of the housing portion 24a.

[0046] Further, as shown in FIG. 5, the inside of the housing portion 24a of the air blowing device 24 is roughly divided into three air flow paths 241, 242, and 243. Among the three air flow paths 241, 242, and 243, the air flow path 241 disposed in the center is the air flow path 241 for air supply. On the other hand, the air flow paths 242 and 243 at both ends are the air flow paths 242 and 243 for exhaust. The air flow path 241 for air supply is configured to communicate with the air outlet 24b. Further, the air flow path 241 for air supply is also configured to communicate with the air supply duct 42 in FIG. 1. On the other hand, the air flow paths 242 and 243 for exhaust communicate with the air inlet 24c and the exhaust duct 32 in FIG. 1.

[0047] When the exhaust fan 31 and the air supply fan 41 in FIG. 1 are driven, an air flow is generated in the exhaust duct 32 and the air supply duct 42, and in the air blowing device 24, air flows in the directions of arrow A and arrow B in FIG. 5 are generated. As a result, air is blown out from the air outlet 24b, and air is blown onto the seat.

[0048] Also, from the air inlet 24c, air is sucked into the exhaust air flow paths 242 and 243, and the sucked air passes through the exhaust air flow paths 242 and 243 and the exhaust duct 32 in FIG. 1 and is discharged outside the image forming apparatus 200. As a result, in the heating device 4, the vapor generated from the sheet is discharged outside the device together with the air in the heating device 4.

[0049] <Problems related to exhaust> By the way, in order to effectively suppress condensation in the heating device, it is preferable to supply warm air or the like into the heating device to increase the temperature inside the heating device. On the other hand, when the vapor in the heating device is discharged outside the device, the air in the heating device is also discharged together with the vapor, resulting in a loss of thermal energy. Therefore, it is preferable to keep the exhaust volume to the minimum necessary.

[0050] However, until now, the exhaust volume has been set according to the conditions when the most vapor is generated. Therefore, when the vapor volume is small, not only is thermal energy discharged unnecessarily, but also the energy for driving the exhaust means is consumed more than necessary, and a large amount of unnecessary energy loss occurs due to exhaust.

[0051] Therefore, in the present invention, in order to reduce the energy loss associated with exhaust, it is proposed to control the exhaust volume based on the amount of vapor generated from the sheet. Hereinafter, taking the first embodiment of the present invention as an example, the characteristic parts of the present invention will be described.

[0052] <Characteristic parts of the present invention> FIG. 6 is a block diagram showing the overall configuration of the control unit 8 according to the first embodiment of the present invention.

[0053] As shown in FIG. 6, the control unit 8 according to the first embodiment of the present invention includes a main control unit 201, a liquid application amount calculation unit 202, a liquid application area calculation unit 203, a conveyance speed setting unit 204, a sheet thickness setting unit 205, a sheet type setting unit 206, a liquid application control unit 207, a conveyance control unit 208, a heating temperature control unit 209, and an exhaust amount control unit 210.

[0054] The liquid application amount calculation unit 202 is a part that calculates the liquid application amount applied to the sheet based on the image information input by the input unit 300. The input unit 300 is, for example, an external device such as a PC (Personal Computer) or a touch panel type input device. The liquid application amount is obtained by calculating the liquid application amount per unit area or per unit time. The information on the liquid application amount calculated by the liquid application amount calculation unit 202 is transmitted to the main control unit 201.

[0055] The liquid application area calculation unit 203 is a part that calculates the liquid application area (liquid application area) of the liquid applied to the sheet based on the image information input by the input unit 300. The liquid application area is obtained by calculating the liquid application area (area ratio) per unit area or per unit time. The information on the liquid application area calculated by the liquid application area calculation unit 203 is transmitted to the main control unit 201.

[0056] The conveyance speed setting unit 204 is a part that sets the conveyance speed of the sheet based on the speed information input by the input unit 300. The information on the conveyance speed set by the conveyance speed setting unit 204 is transmitted to the main control unit 201.

[0057] The sheet thickness setting unit 205 is a part that sets the thickness of the sheet based on the thickness information input by the input unit 300. The input thickness information may be a thickness set in advance for each type of sheet, or instead of the thickness, a basis weight that has a correlation with the thickness of the sheet may be used. The basis weight is a value representing the mass per unit area of the sheet, and generally, as the basis weight increases, the thickness of the sheet also increases. The sheet thickness information set by the sheet thickness setting unit 205 is transmitted to the main control unit 201.

[0058] The sheet type setting unit 206 is a part that sets the type of the sheet based on the type information input by the input unit 300. Examples of the sheet type include plain paper, coated paper with a coating layer formed thereon, and undercoated paper with an undercoat layer further formed on the coating layer. The sheet type information set by the sheet type setting unit 206 is transmitted to the main control unit 201.

[0059] The main control unit 201 is a part that controls the overall operation of the image forming system 100. Specifically, the main control unit 201 is composed of, for example, the CPU 501, ROM 502, RAM 503, and NVRAM 504 shown in FIG. 2.

[0060] The main control unit 201 generates an image formation control signal based on the image information input by the input unit 300. Then, when the image formation control signal is transmitted from the main control unit 201 to the liquid application control unit 207, the liquid application control unit 207 receives the control signal and controls the liquid application operation of the liquid application means 3. Thereby, an image based on the image information is formed on the sheet. Note that the liquid application control unit 207 includes the main scanning driver 508 and the liquid ejection driver 509 shown in FIG. 2.

[0061] Also, the main control unit 201 generates a conveyance speed control signal based on the conveyance speed information set by the conveyance speed setting unit 204. Then, when the conveyance speed control signal is transmitted from the main control unit 201 to the conveyance control unit 208, the conveyance control unit 208 receives the control signal and controls the conveyance operation of the conveyance means 2. Thereby, the sheet is conveyed at the set speed. Note that the conveyance control unit 208 includes the sub-scanning driver 510 shown in FIG. 2.

[0062] Further, the main control unit 201 generates a heating temperature control signal based on the temperature information detected by the heating temperature detection means 400, the information on the liquid application amount calculated by the liquid application amount calculation unit 202, and the thickness information set by the sheet thickness setting unit 205. The heating temperature detection means 400 is a contact or non-contact temperature sensor that detects the temperature of the heating roller 21 or the heating drum 22 of the heating device 4. When the heating temperature control signal is transmitted from the main control unit 201 to the heating temperature control unit 209, the heating temperature control unit 209 receives the control signal and controls the heating temperature of the heating device 4. Thereby, an effective drying process of the sheet is performed. That is, since the thermal energy required to dry the sheet varies depending on the amount of liquid applied to the sheet, the thickness of the sheet, and the temperature of the heating roller 21 or the heating drum 22, the main control unit 201 can effectively promote the drying of the sheet by controlling the temperature of the heating roller 21 or the heating drum 22 based on the information on the liquid application amount, the thickness information of the sheet, and the temperature information of the heating roller 21 or the heating drum 22.

[0063] Further, the main control unit 201 generates an exhaust gas amount control signal based on at least one of the information on the liquid application area calculated by the liquid application area calculation unit 203, the information on the conveyance speed set by the conveyance speed setting unit 204, the thickness information of the sheet set by the sheet thickness setting unit 205, and the sheet type information set by the sheet type setting unit 206. When the exhaust gas amount control signal is transmitted from the main control unit 201 to the exhaust gas amount control unit 210, the exhaust gas amount control unit 210 receives the control signal and controls the exhaust gas amount of the exhaust means 5.

[0064] <Exhaust gas amount control method> Subsequently, the exhaust gas amount control method according to the first embodiment of the present invention will be described.

[0065] FIG. 7 is a diagram showing an example of an exhaust gas amount setting table used to set the exhaust gas amount in the first embodiment of the present invention.

[0066] Here, as items for setting the exhaust volume, four items of "thickness", "type", "conveying speed", and "liquid application area" of the sheet are listed. These "thickness", "type", "conveying speed", and "liquid application area" are all items related to the amount of vapor generated from the sheet. For example, the "thickness" of the sheet increases as the sheet gets thicker, and the amount of moisture contained in the sheet also increases, and the amount of generated vapor also increases. Also, for each level of these items, scores are set in advance (refer to the parentheses in FIG. 7). This score is a value set according to the amount of vapor generated from the sheet, and the larger the score, the higher the level of the item that generates more vapor. In this case, regarding the "thickness" of the sheet, when it is thin, it is set to 1 point, when it is medium, it is set to 3 points, and when it is thick, it is set to 5 points. As the "thickness" increases, the amount of moisture contained in the sheet increases, so the score is set to increase.

[0067] FIG. 8 is a flowchart showing a control flow for controlling the exhaust volume using the exhaust volume setting table according to the first embodiment of the present invention.

[0068] When the control of the exhaust means 5 is started with the start of image formation, first, various information acquisition steps (S1) by the control unit 8 are executed. Specifically, the main control unit 201 in FIG. 6 acquires the "thickness" of the sheet set by the sheet thickness setting unit 205, the "type" of the sheet set by the sheet type setting unit 206, the "conveying speed" set by the conveying speed setting unit 204, and the information of the "liquid application area" calculated by the liquid application area calculation unit 203.

[0069] Subsequently, the control unit 8 performs a total score calculation step (S2) of extracting the scores for each level of each item using the exhaust volume setting table in FIG. 7 and calculating the total of these scores. For example, when the sheet is thin coated paper, the conveying speed is high, and the liquid application area is large, the scores corresponding to the levels of each item are 1 point for the case of thin thickness, 4 points for the case of the type being coated paper, 5 points for the case of high conveying speed, and 8 points for the case of large liquid application area. In this case, when these scores are added up, the total score is 18 points.

[0070] When the control unit 8 calculates the total score, the control unit 8 further executes an exhaust gas volume setting step (S3) of setting the exhaust gas volume level based on the calculated total score. Here, as shown in FIG. 9, the exhaust gas volume level is set in five levels according to the total score. The number of the exhaust gas volume level indicates the size of the exhaust gas volume, and the higher the total score, the higher the exhaust gas volume level is set. For example, when the total score is 18 points, the exhaust gas volume level is set to "4". Note that the exhaust gas volume level is not limited to five levels, and at least two levels or more are sufficient.

[0071] Thereafter, the same control flow is repeatedly performed until the step (S4) where image formation ends. When the image formation ends, the control of the exhaust gas volume also ends accordingly.

[0072] As described above, according to the first embodiment of the present invention, the total score is calculated according to the amount of vapor generated from the sheet, and the exhaust gas volume is set based on the calculated total score, so that the exhaust gas volume can be set according to the amount of vapor. As a result, compared with the case where the exhaust gas volume is set according to the conditions when the most vapor is generated, the energy loss associated with exhaust can be reduced. Therefore, according to the first embodiment of the present invention, energy saving can be achieved by reducing the energy loss associated with exhaust.

[0073] In addition, the control of the exhaust gas volume can be performed by, for example, performing PWM (Pulse Width Modulation) control on the air volume of the exhaust fan 31. The air volume (Q [m 3 / h]) means the amount of air moved by the exhaust fan 31 per unit time, and is represented by the product of the passing wind speed V [m / s] and the passing area A [m 2 . The air volume can be measured using, for example, a hot wire anemometer or a vane anemometer. In addition to adjusting the air volume of the exhaust fan 31, the exhaust gas volume may be controlled by changing the opening amount of the exhaust duct 32 with a damper or the like.

[0074] In addition, when the steam generated from the sheet contains only moisture, the amount of steam can be measured by a general humidity sensor. The "amount of steam" means the amount of steam (mass, weight, amount of substance, etc.) present per unit volume. If the relative humidity and temperature of the steam are known, the absolute humidity can be calculated and the amount of steam can be specified. When the steam contains moisture and a solvent, the amount of steam can be specified by estimating the amount of the solvent from the measurement result of the humidity sensor.

[0075] In addition, since the amount of steam generated from the sheet changes according to the size of the liquid application pattern (image pattern) applied to the sheet, the exhaust volume may be controlled according to the liquid application pattern that changes during one image formation job. Thereby, the exhaust volume can be controlled in real time corresponding to the change of the liquid application pattern, and the exhaust volume corresponding more accurately to the changing amount of steam can be set.

[0076] In addition to being controlled based on each information of "thickness", "type", "conveying speed", and "liquid application area" of the sheet, the exhaust volume may be controlled based on at least one of these four pieces of information. Further, instead of the "liquid application area", the exhaust volume may be controlled using the "liquid application amount" calculated by the liquid application amount calculation unit 202 in FIG. 6.

[0077] In addition, when the exhaust volume is controlled based on the "liquid application area", if the exhaust volume frequently fluctuates with the change of the liquid application area, there is a concern that the rotational speed of the exhaust fan 31 increases or decreases, and the driving sound of the exhaust fan 31 is uncomfortably felt. Further, if the rotational speed of the exhaust fan 31 frequently fluctuates, there is also a risk that the deterioration of the exhaust fan 31 progresses.

[0078] Therefore, the liquid application area calculation unit 203 may calculate the "cumulative average value" of the liquid application area at predetermined time intervals, or at predetermined conveyance distances, or for every predetermined number of image pages, and control the exhaust volume based on the calculated "cumulative average value" of the liquid application area. Specifically, the liquid application area calculation unit 203 calculates the "cumulative average value" of the liquid application area for every 10 pages during the image formation job, and the main control unit 201 corrects the score of the liquid application area in FIG. 7 based on the calculated "cumulative average value", and sets the exhaust volume level based on the total score obtained from the corrected score.

[0079] In this way, by controlling the exhaust volume based on the "cumulative average value" of the liquid application area calculated for every predetermined number of pages, or at predetermined time intervals, or for every predetermined conveyance distance, it becomes possible to improve the problem of driving noise due to frequent fluctuations in the exhaust volume and the problem of deterioration of the exhaust fan 31.

[0080] Next, another embodiment of the present invention will be described. In the following description, mainly the parts different from the first embodiment of the present invention will be described, and the same parts will be omitted as appropriate.

[0081] <Second Embodiment of the Present Invention> FIG. 10 is a schematic configuration diagram of an image forming apparatus 200 according to the second embodiment of the present invention.

[0082] As shown in FIG. 10, in the second embodiment of the present invention, the image forming apparatus 200 includes a vapor sensor 50 that detects the amount of vapor. The vapor sensor 50 is provided in the exhaust duct 32. When the sheet S is heated in the heating device 4, the vapor generated from the sheet S is exhausted through the exhaust duct 32. Therefore, by detecting the amount of vapor in the exhaust duct 32 with the vapor sensor 50, the amount of vapor generated from the sheet S can be specified. The vapor sensor 50 may be a humidity sensor capable of detecting the amount of water vapor, or a solvent sensor capable of detecting the amount of vaporized solvent, or may include both of these.

[0083] In addition, in the third embodiment of the present invention, the control unit 8 is configured to control the exhaust amount of the exhaust means 5 based on the "steam amount" detected by the steam sensor 50.

[0084] FIG. 11 is a block diagram showing a partial configuration of the control unit 8 according to the second embodiment of the present invention.

[0085] As shown in FIG. 11, the main control unit 201 included in the control unit 8 acquires information on the steam amount detected by the steam sensor 50 from the steam sensor 50. Then, the main control unit 201 generates an exhaust amount control signal based on the acquired steam amount. When the exhaust amount control signal is transmitted from the main control unit 201 to the exhaust amount control unit 210, the exhaust amount control unit 210 receives the control signal and controls the exhaust amount of the exhaust means 5. Thereby, the exhaust amount is set according to the steam amount generated from the seat.

[0086] In this way, the exhaust amount may be controlled based on the "steam amount" detected by the steam sensor 50. Also in this case, the exhaust amount can be set according to the steam amount generated from the seat, the energy loss associated with exhaust can be reduced, and energy saving can be achieved.

[0087] <The Third Embodiment of the Present Invention> FIG. 12 is a schematic configuration diagram of the image forming apparatus 200 according to the third embodiment of the present invention.

[0088] As shown in FIG. 12, in the third embodiment of the present invention, the control unit 8 is configured to control not only the exhaust means 5 but also the air supply means 6.

[0089] FIG. 13 is a block diagram showing a partial configuration of the control unit 8 according to the third embodiment of the present invention.

[0090] As shown in Fig. 13, in the third embodiment of the present invention, the control unit 8 includes, in addition to the exhaust gas amount control unit 210, an intake air amount control unit 211 that controls the intake air amount of the intake air means 6. When generating the exhaust gas amount control signal, the main control unit 201 generates an intake air amount control signal based on the exhaust gas amount at that time. Then, when the intake air amount control signal is transmitted from the main control unit 201 to the intake air amount control unit 211, the intake air amount control unit 211 receives the control signal and controls the intake air amount of the intake air means 6. The control of the intake air amount may be performed, for example, by controlling the air volume of the intake air fan 41 included in the intake air means 6, or by changing the opening amount of the intake air duct 42. In Fig. 13, the main control unit 201 may control the exhaust gas amount based on at least one of the "thickness", "type", "conveying speed", and "liquid application area" of the sheet, or may control the exhaust gas amount based on the "amount of steam" detected by the steam sensor 50.

[0091] In this way, by controlling the intake air amount based on the exhaust gas amount, the air pressure in the heating device 4 can be maintained at a predetermined pressure. That is, when the exhaust gas amount is controlled to increase, the intake air amount can be controlled to increase accordingly, thereby suppressing fluctuations in the air pressure in the heating device 4. Usually, the air pressure in the heating device 4 is preferably set to a negative pressure in order to prevent steam from leaking out of the heating device 4. Therefore, by controlling the intake air amount according to the exhaust gas amount as in the third embodiment of the present invention, the inside of the heating device 4 can be maintained at a negative pressure, and steam leakage from the heating device 4 can be effectively prevented.

[0092] <Fourth Embodiment of the Present Invention> Fig. 14 is a schematic configuration diagram of an image forming apparatus 200 according to the fourth embodiment of the present invention.

[0093] As shown in Fig. 14, in the fourth embodiment of the present invention, the heating device 4 includes an in-device temperature sensor 51 that detects the temperature inside the heating device 4.

[0094] Fig. 15 is a block diagram showing a partial configuration of the control unit 8 according to the fourth embodiment of the present invention.

[0095] As shown in Fig. 15, in the fourth embodiment of the present invention, the control unit 8 is configured to control the exhaust volume of the exhaust means 5 based on both the "amount of vapor" generated from the sheet and the "temperature" detected by the in-device temperature sensor 51. Here, the "amount of vapor" generated from the sheet may be obtained based on at least one of the "thickness", "type", "conveying speed", and "liquid application area" of the sheet, or may be the "amount of vapor" detected by the vapor sensor 50.

[0096] By discharging the vapor generated in the heating device 4 to the outside of the device, condensation in the heating device 4 can be suppressed. However, when image formation is started immediately or when the indoor temperature is low, the temperature in the heating device 4 becomes low, so the vapor generated in the heating device 4 is likely to condense. Therefore, when the temperature in the heating device 4 is low, it is preferable to increase the exhaust volume to suppress condensation.

[0097] Therefore, in the fourth embodiment of the present invention, the exhaust volume is controlled based on the "amount of vapor" generated from the sheet and the "temperature" in the heating device 4 in addition to the "amount of vapor". As a result, the exhaust volume can be controlled according to the temperature in the heating device 4. For example, when the temperature in the heating device 4 is low immediately after the start of image formation, the exhaust volume level is increased by one step compared to when the temperature is high to increase the exhaust volume. Thereby, condensation when the temperature is low can be effectively suppressed. Also, when the temperature in the heating device 4 becomes high during image formation, the exhaust volume level is lowered by one step and returned to the original state, whereby the energy loss associated with exhaust can be reduced.

[0098] In the fourth embodiment of the present invention, the control unit 8 is not configured to control the air supply means 6 based on the exhaust volume. However, in such an embodiment, the control unit 8 may be configured to control the air supply means 6 based on the exhaust volume.

[0099] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments and can be appropriately modified without departing from the gist of the invention.

[0100] In addition, the present invention is applicable not only to an image system that forms an image on a sheet, but also to other liquid application systems. For example, the present invention may be applied to a liquid application system that applies a treatment liquid or the like for modifying the surface of a sheet before image formation. Further, the present invention is also applicable to a liquid application system that applies a liquid to a sheet by a method other than ejection, such as applying a liquid to a sheet using a roller. Further, the heating device included in the liquid application system may be a device that heats a sheet for purposes other than drying, such as fixing an image on the sheet.

[0101] In addition, the sheet used in the present invention may be at least temporarily capable of having a liquid adhered thereto, and may be one to which the liquid adheres and adheres, or one to which the liquid adheres and penetrates. Specifically, the sheet includes, in addition to paper, resin films, wallpapers, electronic substrates, and the like. In addition, examples of the material of the sheet include paper, leather, metal, plastic, glass, wood, ceramics, and the like. Further, the sheet is not limited to being a long sheet that is continuously conveyed without interruption from the sheet supply means to the sheet recovery means, and may be a short sheet that is independently conveyed one by one without being continuous from the sheet supply means to the sheet recovery means.

[0102] In addition, the liquid applied to the sheet is not particularly limited, but includes solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments, and solutions, suspensions, emulsions, and the like containing these. These are used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements, components of light-emitting elements, liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0103] Summarizing the aspects of the present invention described above, the present invention includes at least the following aspects.

[0104] [First Aspect] The first aspect is a liquid application system including a liquid application means for applying a liquid to a sheet, a heating device for heating the sheet to which the liquid has been applied, an exhaust means for exhausting air in the heating device, and a control unit for controlling the exhaust means, wherein the control unit controls the exhaust amount of the exhaust means based on the amount of vapor generated from the sheet in the heating device.

[0105] Here, the heating device may have an individual housing 20 as shown in FIG. 1, or may be housed in the housing 250 of the image forming apparatus 200 together with the liquid application means 3 or the like without having an individual housing 20. Therefore, the exhaust means for exhausting air in the heating device may be any means for exhausting the air in the housing having at least the heating means such as the heating roller 21 or the heating drum 22 in FIG. 1 to the outside of the housing. For example, when the heating device 4 does not have an individual housing 20 as shown in FIG. 1 and is housed in the housing 250 of the image forming apparatus 200 together with the liquid application means 3 or the like, the exhaust means may be any means for exhausting the air in the housing 250 of the image forming apparatus 200 to the outside. Further, the amount of vapor may be the amount of water vapor generated from the sheet and the liquid on the sheet, or the amount of vaporization of the solvent generated from the liquid on the sheet. Further, the amount of vapor may be an amount including both water vapor and the solvent.

[0106] [Second Aspect] The second aspect is the first aspect, wherein the control unit controls the exhaust amount of the exhaust means based on at least one of the thickness, type, conveyance speed, and liquid application area of the sheet.

[0107] [Third Aspect] The third aspect is the first or second aspect, wherein the control unit controls the exhaust amount of the exhaust means in accordance with a change in the liquid application pattern applied to the sheet.

[0108] [Fourth Aspect] The fourth aspect is any one of the first to third aspects, wherein the control unit controls the exhaust amount of the exhaust means based on the cumulative average value of the liquid application area calculated for each predetermined number of pages, or for each predetermined time, or for each predetermined conveyance distance.

[0109] [Aspect 5] In the fifth aspect, in the first aspect, a vapor sensor is provided for detecting the amount of vapor generated from the sheet in the heating device, and the control unit controls the exhaust amount of the exhaust means based on the amount of vapor detected by the vapor sensor.

[0110] [Aspect 6] In the sixth aspect, in any one of the first to fifth aspects, an air supply means for supplying air into the heating device is provided, and the control unit controls the air supply amount of the air supply means based on the exhaust amount of the exhaust means.

[0111] Here, the heating device supplied with air by the air supply means may have an individual housing 20 as shown in FIG. 1, or may be housed in the housing 250 of the image forming apparatus 200 together with the liquid applying means 3 or the like without having an individual housing 20. Therefore, the air supply means may be any means for supplying air into a housing having at least the heating means inside.

[0112] [Aspect 7] In the seventh aspect, in any one of the first to sixth aspects, an in-device temperature sensor for detecting the temperature inside the heating device is provided, and the control unit controls the exhaust amount of the exhaust means based on both the amount of vapor generated from the sheet in the heating device and the temperature detected by the in-device temperature sensor.

[0113] Here, the heating device in which the in-device temperature sensor is provided may have an individual housing 20 as shown in FIG. 1, or may be housed in the housing 250 of the image forming apparatus 200 together with the liquid applying means 3 or the like without having an individual housing 20. Therefore, the in-device temperature detecting means may be any means for detecting the temperature inside a housing having at least the heating means inside.

[0114] [Aspect 8] The eighth aspect is that, in any one of the first to seventh aspects, the liquid application system is an image forming system that applies liquid to the sheet to form an image.

[0115] [Ninth Aspect] The ninth aspect is an exhaust gas amount control method for controlling the amount of exhaust gas exhausted from a heating device that heats a sheet, and the exhaust gas amount is an exhaust gas amount control method controlled based on the amount of vapor generated from the sheet in the heating device.

Explanation of Reference Signs

[0116] 3 Liquid application means 4 Heating device 5 Exhaust means 6 Air supply means 8 Control unit 50 Vapor sensor 51 In-device temperature sensor 100 Image forming system (liquid application system) S Sheet

Prior Art Documents

Patent Documents

[0117]

Patent Document 1

Claims

1. Liquid applying means for applying liquid to a sheet, A heating device for heating the sheet to which the liquid has been applied, Exhaust means for exhausting air in the heating device, A control unit for controlling the exhaust means, A liquid applying system comprising: The control unit controls the exhaust amount of the exhaust means based on the amount of vapor generated from the sheet in the heating device. A liquid applying system characterized by this.

2. The liquid applying system according to claim 1, wherein the control unit controls the exhaust amount of the exhaust means based on at least one of the thickness, type, conveyance speed, and liquid application area of the sheet.

3. The liquid applying system according to claim 1, wherein the control unit controls the exhaust amount of the exhaust means according to a change in the liquid application pattern applied to the sheet.

4. The liquid applying system according to claim 1, wherein the control unit controls the exhaust amount of the exhaust means based on the cumulative average value of the liquid application area calculated for each predetermined number of pages, or for each predetermined time, or for each predetermined conveyance distance.

5. Comprising a vapor sensor for detecting the amount of vapor generated from the sheet in the heating device, The liquid applying system according to claim 1, wherein the control unit controls the exhaust amount of the exhaust means based on the amount of vapor detected by the vapor sensor.

6. Comprising air supply means for supplying air into the heating device, The liquid applying system according to claim 1, wherein the control unit controls the air supply amount of the air supply means based on the exhaust amount of the exhaust means.

7. Comprising an in-device temperature sensor for detecting the temperature in the heating device, The liquid applying system according to claim 1, wherein the control unit controls the exhaust amount of the exhaust means based on both the amount of vapor generated from the sheet in the heating device and the temperature detected by the in-device temperature sensor.

8. The liquid applying system according to claim 1, wherein the liquid applying system is an image forming system for forming an image by applying liquid to the sheet.

9. An exhaust amount control method for controlling the exhaust amount exhausted from a heating device for heating a sheet, The exhaust amount is controlled based on the amount of vapor generated from the sheet in the heating device. An exhaust amount control method characterized by this.

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