JP2017145125A - Sheet humidifier and sheet post-processing device, image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet humidifier which recovers a humidification liquid from a water supply tank for retaining the humidification liquid to be supplied to a sheet and prevents a water supply roller from remaining soaked in the humidification liquid even when the device is stopped.SOLUTION: A sheet humidifier has a recovery part which recovers a humidification liquid, which is retained in a water supply tank 407 and naturally discharged, into a water storage tank 420 when the device is stopped. The recovery part communicates with the water supply tank so that a water surface of the humidification liquid in the water supply tank is positioned below a lowermost part of a water supply roller 402 when the humidification liquid retained in the water supply tank is recovered from the recovery part when the device is stopped.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sheet humidifying device that applies a humidifying liquid to a sheet, a sheet post-processing device including the sheet humidifying device, and an image forming apparatus.

  Conventionally, in an image forming apparatus using an electrophotographic system, a toner image formed on a photosensitive drum as an image carrier is transferred to a recording sheet, and the recording sheet is heated and pressed by a fixing device to form a toner image. It is fixed on the recording sheet. The fixing device includes a fixing roller having a heater inside, and a heat roller fixing for fixing the toner image by passing the recording sheet through a fixing nip formed by a pressure roller rotating in pressure contact with the fixing roller. Many methods are generally adopted.

  In the heat roller fixing step, heat and pressure are applied to the sheet on which the toner image has been transferred almost simultaneously, so that moisture inside the sheet evaporates under pressure. The phenomenon called “curl” that causes the sheet itself to be greatly curved due to the “change in moisture content in the sheet” and the “stress applied to the sheet” that occur at this time, and the sheet edge portion “wasted” instead of being linear. A phenomenon called “rippling” having such a shape occurs.

  Here, “paper”, which is most commonly used as a sheet, is seen at the fiber level. Paper is composed of short fibers entangled with each other, and moisture is contained inside or between the fibers. Furthermore, since the fiber and water are in an equilibrium state with hydrogen bonds formed, the fibers and water are kept smooth.

  However, when heat and pressure are applied to the paper almost simultaneously in the fixing process, the fibers are displaced due to the pressure. In this state, when heat is applied and moisture evaporates, further hydrogen bonds are formed between the fibers and deform. If the paper is left unattended, it absorbs moisture from the environment, and the hydrogen bonds between the fibers are cut off again to return to the original state. However, there is no moisture between some fibers, which keeps the deformation. As described above, the deformation pattern includes “curl” and “waving”, and “curl” is caused by the difference in expansion and contraction of the front and back of the paper. “Wavy” occurs due to the difference in expansion and contraction between the center and the edge of the paper.

  To solve the above problem, as disclosed in Patent Document 1, the water lost in the fixing process is replenished by adding water to the paper that has been deprived of water by heat and pressure, thereby improving the “rippling” and “curl”. There has been proposed a device to be used. When the moisture of the paper increases, the Young's modulus of the paper itself decreases, the stiffness is reduced, and waviness is reduced. Further, it is considered that when moisture enters the gaps between the fibers, the bonds between the fibers once hydrogen-bonded by the fixing device are separated again to reduce the undulation.

  In patent document 1, the tank which stores the water used for humidification is arrange | positioned under the humidification part, The water stored in the tank is sent to a humidification part with a pump, and a fixed quantity is stored in a water supply tank. On the water tank, a water supply roller using a hydrophilic rubber member is arranged so as to rotate while immersing a part of the peripheral surface in water, and the water pumped up by adhering to the peripheral surface of the water supply roller. Is applied to the sheet via a humidifying roller.

  The amount of water sent from the pump to the water tank is set to be larger than the amount of water pumped from the water tank attached to the peripheral surface of the water supply roller, and the water overflowed from the water tank is returned to the tank and used repeatedly. It is stated that. Since the water level in the water supply tank is always kept full and the inundation range of the peripheral surface of the water supply roller is constant, the amount of water drawn by the replenishing roller is constant, and the amount of water applied to the sheet is stabilized.

JP2009-234679

  However, in the sheet humidifier of Patent Document 1, the water sent to the water tank by the pump remains accumulated in the water tank even when the apparatus is stopped. As a result, the following problems occur.

  The water supply roller is always immersed in water even when the apparatus is stopped, and rubber deterioration occurs. Specifically, the rubber plasticizer oozes out, and changes in hardness and diameter occur.

  In addition, the water tank is always full, so when vibration is applied, water spills, causing contamination in the apparatus and failure. In particular, water may be spilled when the humidifying unit is pulled out from the sheet humidifying device main body by jamming or the like.

  In order to solve these problems, it is conceivable that a valve is provided in the water supply path from the pump to the water supply tank so that when the valve is opened, the water in the water supply pipe and the water supply tank is collected in the tank. However, in the case of a manual valve, not only is it necessary to operate the valve every time the apparatus is stopped or jammed, but if the valve is operated incorrectly, water is not normally applied to the sheet. If an electromagnetic valve is provided instead of the manual valve, it is possible to automatically collect water when the apparatus is stopped or jammed. However, in this case, the cost of the apparatus increases.

  In view of the above problems, the present invention provides a sheet humidifying apparatus capable of recovering a humidifying liquid from a holding unit that holds the humidifying liquid supplied to the sheet with a simple and low-cost configuration, and a sheet post-processing apparatus using the same. An image forming apparatus is provided.

  In order to achieve the above object, a typical configuration according to the present invention includes a sheet humidifying device for humidifying a conveyed sheet, a supply member for supplying a humidifying liquid to the sheet, and a part of the supply member A holding unit that holds the humidifying liquid so as to be immersed in the humidifying liquid, a storage unit that stores the humidifying liquid, a supply unit that supplies the humidifying liquid stored in the storage unit to the holding unit, and A discharge unit that returns the humidified liquid that has overflowed from the holding unit to the storage unit; and a recovery unit that collects the humidified liquid held in the holding unit into the storage unit by natural discharge, and holds the holding liquid from the storage unit. When the humidifying liquid is not supplied to the part and the humidifying liquid held in the holding part is recovered from the collecting part, the liquid level of the humidifying liquid in the holding part is lower than the lowest part of the supply member. It is characterized by that.

  According to the present invention, it is possible to collect the humidifying liquid in the holding part in the housing part with a simple and low-cost configuration, and to prevent the supply member from deteriorating and the humidifying liquid from spilling in the holding part.

1 is a cross-sectional view of an image forming apparatus including a sheet humidifier according to an embodiment of the present invention. It is sectional drawing which shows the state in operation | movement of the sheet humidification apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the state in the stop of the sheet humidification apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the state in operation | movement of the sheet humidification apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the state in the stop of the sheet humidification apparatus which concerns on 2nd Embodiment of this invention.

  Next, the sheet humidifying device of the present invention will be described. Here, a sheet post-processing apparatus having a sheet humidifying apparatus will be exemplified, and description will be given together with an image forming apparatus provided with the sheet post-processing apparatus.

[First Embodiment]
<Image forming apparatus>
FIG. 1 is a cross-sectional view of an image forming apparatus 500 including a sheet post-processing apparatus 900 according to the first embodiment of the present invention. In this embodiment, a color electrophotographic printer is exemplified as the image forming apparatus, and a sheet waviness correction apparatus that corrects waviness generated in the sheet is exemplified as the sheet post-processing apparatus. The sheet P used in the present embodiment may be any sheet that can form a toner image. Specific examples thereof include plain paper, resin-like sheets that are substitutes for plain paper, cardboard, and overhead projectors. Can be used.

  The overall configuration of the image forming apparatus will be described together with the image forming operation. A printer 500 shown in FIG. 1 includes an image forming unit 510 for each color of yellow, magenta, cyan, and black. A photosensitive drum 511 as an image carrier is charged by a charging roller 512 and then a latent image is formed by a laser scanner 513. The latent image is developed by the developing device 514 to become a toner image, which is visualized. The toner image on the photosensitive drum 511 is sequentially transferred to, for example, an intermediate transfer belt 531 that is an intermediate image carrier.

  On the other hand, the sheets P are fed one by one from the feeding cassette 520 and fed to the registration roller pair 523. When the sheet P is skewed, the skew is corrected by the front end of the sheet P being abutted against the registration roller pair 523. The registration roller pair 523 sends the sheet P to the transfer nip formed by the intermediate transfer belt 531 and the secondary transfer roller 535 in synchronization with the toner image on the intermediate transfer belt 531. The toner image on the intermediate transfer belt is transferred to the sheet P by applying a bias to the secondary transfer roller 535. Thereafter, the toner image on the sheet P is fixed on the sheet P by being heated and pressed by the fixing device 100, and then sent to the sheet wavy correction device 900 by the main body discharge roller 540. The sheet P subjected to the wave correction by the sheet wave correcting device 900 is discharged onto the discharge tray 565.

  The fixing device 100 includes a fixing roller 110 with a built-in heater and a heat roller pair of a pressure roller 111. Due to the heat and pressure applied when the sheet P passes through the fixing device 100, the end of the sheet is stretched depending on the type of the sheet, and the length of the sheet differs between the end and the center. Partial undulation may occur. The type of sheet P in the feeding cassette 520 is input by the user using the operation panel 570, and information is sent to the CPU and memory in the image forming apparatus.

<Sheet post-processing device>
In order to correct the waviness, in this embodiment, a sheet humidifier (hereinafter referred to as “humidifier”) 400 as a sheet post-processing device and a sheet processing unit that performs predetermined processing on the sheet humidified by the humidifier 400 are provided. It has been. In the present exemplary embodiment, the sheet processing unit includes the sheet pulling and conveying apparatuses 101, 201, and 301 and the curl correcting apparatus 600, and the sheet post-processing apparatus is configured as the sheet wavy correction apparatus 900 together with the humidifying apparatus 400. The sheet P on which the toner image is fixed by being heated and pressed by the fixing device 100 is sent to the humidifying device 400 by the main body discharge roller 540 and the inlet roller 901 of the sheet wavy correction device 900. Here, the sheet P is humidified by the humidifying roller pair 401 and 402.

  The sheet P discharged from the humidifying device 400 is sent to the sheet pulling and conveying devices 101, 201, and 301 as a sheet pulling unit that continuously pulls the sheet. After humidifying to a predetermined amount of moisture by the humidifier 400, the sheet pulling and conveying apparatus 101, 201, 301 pulls the central part in the width direction of the sheet, thereby reducing the difference in sheet length between the end and the center. Waves are corrected. Note that the sheet is pulled by changing the conveyance speed between the end in the sheet width direction and the center.

  A curl correction device 600 is provided downstream of the sheet pulling and conveying devices 101, 201, and 301 in the sheet conveying direction. The curl correction apparatus 600 includes a first curl correction unit 601 for correcting the curl of a sheet convex on one surface side, and a second for correcting the curl of a sheet convex on the other surface side. The curl correction unit 602 is configured. Each straightening portion is composed of a roller pair in which a sponge roller is pressed against a rigid roller, and the curled sheet passes through the curved nip portion of the sponge roller that is generated when the rigid roller bites into the sponge roller. It corrects the curl of the sheet.

  The sheet P whose undulation is corrected by the tension and curl correction of the humidified sheet is conveyed by the conveyance rollers 902, 903, and 904, discharged by the discharge roller 905 to the outside of the sheet undulation correction device 900, and stacked on the discharge tray 565. Is done.

  Reference numeral 420 denotes a water storage tank in which a humidifying liquid LQ for adding moisture to the sheet P to humidify is stored. The humidifying liquid LQ accommodated in the water storage tank 420 is supplied with water through the water supply pipe 422 at any time toward the water supply tank provided in the humidifying device 400 by the pump 421. The humidifying liquid LQ is mainly composed of water.

<Humidifying device>
Next, the configuration of the humidifier 400 will be specifically described with reference to FIG. FIG. 2 is a cross-sectional view of the humidifier 400 according to this embodiment. The humidifier 400 has a substantially symmetric configuration with respect to the sheet conveyance path in order to humidify both sides of the sheet P while nipping and conveying the sheet P. For this reason, members having the same function and disposed across the sheet conveyance path are denoted by the same reference numerals.

  The water supply frame 406 is provided with a water supply tank 407 that is a holding unit for holding the humidifying liquid. A water storage tank 420, which is a storage portion that stores a humidifying liquid, is disposed below the water tank in the direction of gravity, and the water storage tank 420 is filled with the humidifying liquid LQ supplied to the water tank 407.

  Above the water supply tank 407, a primary water supply roller 402 as a supply member that supplies the humidifying liquid to the sheet is disposed so that a part of the peripheral surface is immersed in the humidifying liquid LQ filled in the water supply tank 407. . The primary water supply roller 402 is an elastic material in which a solid rubber layer mainly composed of a material having a hydrophilic surface capable of holding water on a shaft core surface made of a rigid metal body such as stainless steel, such as NBR, is formed. Laura. When the primary water supply roller 402 is driven to rotate, the humidified liquid LQ in the water supply tank 407 adheres to the hydrophilic surface of the primary water supply roller 402 and is pumped up.

  A first regulating roller 404 is in contact with the primary water supply roller 402 on the downstream side in the rotational driving direction with respect to the water supply tank 407 facing position. The first regulating roller 404 is a roller in which the surface of the shaft core made of a metal rigid body such as stainless steel is plated with nickel, chromium or the like. The first regulating roller 404 is in contact with the primary water supply roller 402, suppresses the amount of the humidifying liquid LQ held on the surface of the solid rubber layer of the primary water supply roller 402 to an appropriate amount, and adjusts the amount of moisture supplied to the sheet P. .

  The secondary water supply roller 403 is in contact with the primary water supply roller 402 on the downstream side in the rotational driving direction from the contact position of the first regulating roller 404. As with the primary water supply roller 402, the secondary water supply roller 403 has a solid rubber layer mainly composed of a material having a hydrophilic surface, such as NBR, on the shaft core surface made of a metal rigid body such as stainless steel. Elastic roller. The humidification liquid LQ adhering to the primary water supply roller 402 is adjusted in adhering amount by the first regulating roller 404 and then the hydrophilicity of the secondary water supply roller 403 in the nip formed by the primary water supply roller 402 and the secondary water supply roller 403. Delivered to the surface.

  The humidifying roller 401 is in contact with the secondary water supply roller 403 on the downstream side in the rotational drive direction from the contact position of the first regulating roller 404. The humidifying roller 401 is an elastic roller in which a solid rubber layer mainly composed of NBR, silicon or the like is formed on the surface of a shaft core made of a metal rigid body such as stainless steel. The humidifying liquid LQ adhering to the hydrophilic surface of the secondary water supply roller 403 is delivered to the hydrophilic surface of the humidifying roller 401 at the nip formed by the secondary water supply roller 403 and the humidifying roller 401.

  A second regulating roller 405 is in contact with the humidifying roller 401 on the downstream side in the rotational driving direction from the contact position of the secondary water supply roller 403. The second regulating roller 405 regulates the amount of moisture supplied to the sheet P by suppressing the amount of the humidifying liquid held on the surface of the solid rubber layer of the humidifying roller 401 to an appropriate amount.

  Thus, the humidifying liquid LQ pumped up by the primary water supply roller 402 serving as the supply member is sequentially transferred to the secondary water supply roller 403 and the humidification roller 401, and is then supplied by the first restriction roller 404 and the second restriction roller 405. And is supplied to a humidifying nip formed by the humidifying roller 401 pair across the sheet conveyance path.

  The sheet P on which the image has been transferred and fixed in the printer 500 is conveyed in the direction of arrow B in FIG. 2, guided by the entry guide 414, and sent to the humidifying nip formed by the humidifying roller 401 pair. It is humidified by being applied to the surface. As a result, the sheet P is humidified to an optimum moisture amount, and the tension effect by the sheet tension conveying devices 101, 201, 301 is promoted.

  The sheet P that has passed through the nip portion of the humidifying roller 401 is sent to the sheet first tensile conveyance device 101 through the discharge guide 415, and the undulation caused by the fixing heating is corrected by pulling the humidified sheet.

(Humidizing liquid circulation configuration)
Next, the circulation configuration of the humidifying liquid LQ of the humidifying device 400 according to the present embodiment will be described with reference to FIGS. FIG. 2 shows a state during operation of the humidifying device 400 of this embodiment, and FIG. 3 shows a state during stoppage.

  Reference numeral 420 denotes a water storage tank in which a humidifying liquid LQ for humidifying the sheet P is accommodated, and is disposed below the humidifying device 400 in the gravity direction. The humidifying liquid LQ accommodated in the water storage tank 420 is pumped upward through the water supply pipe 422 by a pump 421 serving as a supply unit.

  The water supply pipe 422 is connected to a water supply port 409 provided in the water supply tank 407, and the humidified liquid LQ pumped up from the water storage tank 420 is supplied to the water supply tank 407. The upper part of the water tank 407 is open, and an open water tank 407 is formed. During the operation of the humidifier 400, the pump 421 is continuously driven, and the humidifying liquid LQ overflows from the edge 408 of the water supply tank and flows down to the drain groove 412 which is a humidifying liquid receiving part formed in the water supply frame 406. A drainage port 413 is formed in the lower part of the drainage groove 412, and a drainage pipe 423 is connected to the drainage port 413 and connected to the water storage tank 420. As a result, of the humidified liquid supplied to the water supply tank 407, a discharge part is formed to return the humidified liquid overflowed from the water supply tank 407 to the water storage tank 420, and the humidified liquid LQ overflowed from the water supply tank 407 is drained by its own weight. And is collected in the water storage tank 420.

  Further, in the humidifier of the present embodiment, a recovery unit is provided that connects the water supply tank 407 and the water storage tank 420 and recovers the humidified liquid in the water supply tank 407 to the water storage tank 420 by natural discharge. Here, the spontaneous discharge means that the humidified liquid is discharged by the weight of the humidified liquid through the communicating path regardless of pumping by the pump or opening / closing operation of the valve. In this collection unit, a water tank drain port (discharge port) 410 is formed in the lower part of the water tank 407, one end of the water tank drain pipe 411 is connected to the water tank drain port 410, and the other end is connected to the drain groove 412. Connected and configured. In other words, the drainage path of the humidified liquid that communicates from the water supply tank 407 to the water storage tank 420 through the water supply tank drain port 410, the water supply / drain pipe 411, the drain groove 412, and the drain pipe 423 is configured as a recovery unit. Thereby, the humidifying liquid LQ filled in the water tank 407 flows down from the water tank drain port 410 to the drain groove 412 through the water tank drain pipe 411 by its own weight, and flows into the water storage tank 420 and is collected.

  The flow rate of the humidifying liquid discharged from the water supply tank 407 via the water supply tank drain pipe 411 is determined based on the flow rate of the humidifying liquid supplied to the water supply tank 407 by the pump 421 from the humidifying liquid in the water supply tank 407. The diameters of the water tank drain port 410 and the water tank drain pipe 411 are set to be smaller than the amount obtained by subtracting the amount supplied to the roller 402.

  In the case of this embodiment, the pumping capacity of the pump 421 is 300 ml per minute. On the other hand, the amount of the humidifying liquid LQ flowing down through the water tank drain pipe 411 is 50 ml per minute for the water tank 407 on one side, and 100 ml per minute in total on both sides across the sheet conveyance path. Further, the amount of the humidifying liquid LQ pumped up from the water supply tank 407 by the primary water supply roller 402 is 75 ml per minute for the water supply tank 407 on one side, and 150 ml per minute in total on both sides across the sheet conveyance path. That is, during the operation of the humidifier 400, the humidifying liquid is supplied to the water supply tank 407 from a total of 250 ml of the humidifying liquid LQ that is pumped up by the primary water supply roller 402 and discharged from the water supply tank 407 by drainage through the water supply tank drain pipe 411. The amount of 300ml is 50ml more. Since 50 ml of humidified liquid LQ constantly overflows from the water tank 407, the liquid level of the water tank 407 is constant at the height of the edge 408 of the water tank as shown in FIG. . For this reason, the width in which the surface of the primary water supply roller 402 is immersed in the humidifying liquid LQ is always constant, and the humidifying liquid LQ can be pumped stably.

(The humidifier is stopped)
Next, a state where the operation of the humidifier 400 is stopped will be described with reference to FIG. When the operation of the humidifier 400 stops, the pumping of the humidifying liquid LQ by the pump 421 stops. On the other hand, the humidifying liquid LQ stored in the water tank 407 is drained by its own weight through the water tank drain pipe 411 to the drain groove 412 and is collected in the water tank 420 through the drain pipe 423. As shown in FIG. 3, the liquid level of the humidifying liquid LQ after the end of drainage is the height of the water supply tank drain port 410. The position of the water tank drain port 410 is arranged at a position lower than the lowermost part 402B of the primary water supply roller. For this reason, when the humidifier 400 is stopped, the primary water supply roller 402 does not touch the humidifying liquid LQ, and rubber deterioration is prevented.

  Further, even when the humidifying device 400 is pulled out from the sheet wavy correction device 900 by jamming or the like, the humidifying liquid LQ does not accumulate in the water supply tank 407, so that the humidifying liquid LQ does not spill and contamination or failure in the device. Can be prevented.

  When the humidifying device 400 is operated again, the water supply tank 407 can be filled with the humidifying liquid LQ before starting the humidifying operation by operating the pump 421 during the startup time of the printer 500.

  The water tank drain port 410 communicates with the water storage tank 420 from the water tank drain pipe 411 through the drain groove 412 and the drain pipe 423. For this reason, drainage from the water supply tank 407 is performed by the weight of the humidifying liquid LQ, and the operator of the apparatus does not need to perform any operation for drainage. Further, it is not necessary to add a solenoid valve for switching the flow path, a pump for draining, or the like, and drainage from the water supply tank 407 is possible with a simple and inexpensive configuration.

  In the present embodiment, the water tank drain port 410 and the drain groove 412 provided at the lower part of the water tank 407 are connected by the water tank drain pipe 411. However, the configuration for always draining a constant amount from the water tank 407 is as follows. It is not limited to this. For example, a cutout may be provided in a part of the wall surface surrounding the water supply tank 407 so that the height of the cutout bottom is lower than the lowest part 402B of the primary water supply roller.

[Second Embodiment]
Next, a second embodiment of the sheet humidifier according to the present invention will be described. The second embodiment differs from the humidifier 400 of the first embodiment in the method of discharging the humidifying liquid LQ from the water supply tank 407, and the other configurations are the same. Therefore, the description of the configurations and operations of the humidifier and the image forming apparatus is omitted.

  A circulation configuration of the humidifying liquid LQ of the humidifying device 400 of the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 shows the operating state of the humidifying device 400 of this embodiment, and FIG. 5 shows the stopped state.

  In the humidifying device 400 of this embodiment, a branch joint 424 is attached to a water supply pipe 422 that connects the pump 421 and the water supply tank 407. One end of a branch drain pipe 425 is connected to the branch joint 424, and the other end of the branch drain pipe 425 is connected to the drain pipe 423. In this way, the supply path and the discharge path of the humidifying liquid are communicated by the drain pipe 423, and a part of the humidifying liquid LQ pumped up by the pump 421 flows down the drain pipe 423 and is collected in the water storage tank 420. Has been. That is, in the present embodiment, the route connected to the branch drainage pipe 425, the drainage pipe 423, and the water storage tank 420 from the water supply tank 407 through the water supply pipe 422 is the humidification liquid in the water supply tank 407 when the apparatus is stopped. It is comprised as a collection | recovery part to collect | recover. The branch drain pipe 425 is provided with a flow rate adjustment valve 426 that is a flow rate adjustment unit capable of adjusting the discharge amount, and the amount of the humidified liquid LQ drained by its own weight via the branch drain pipe 425 can be adjusted.

  The pumping capacity of the pump 421 of this embodiment is 300 ml per minute. On the other hand, the amount of the humidifying liquid LQ drained through the branch drain pipe 425 is adjusted by the flow rate adjusting valve 426 so as to be 100 ml per minute. Further, the amount of the humidifying liquid LQ pumped from the water supply tank 407 by the primary water supply roller 402 is 75 ml per minute for the water supply tank 407 on one side, and 150 ml per minute in total on both sides across the sheet conveyance path. That is, during the operation of the humidifier 400, the supply amount of the humidifying liquid to the water supply tank 407 from the total 250 ml of the humidifying liquid LQ that is pumped up by the primary water supply roller 402 and discharged from the water supply tank 407 by drainage through the branch drain pipe 425. 300ml is 50ml more. Since 50 ml of humidified liquid LQ constantly overflows from the water tank 407, the liquid level of the water tank 407 is constant at the height of the edge 408 of the water tank as shown in FIG. . For this reason, the width in which the surface of the primary water supply roller 402 is immersed in the humidifying liquid LQ is always constant, and the humidifying liquid LQ can be pumped stably.

  Subsequently, a state in which the operation of the humidifier 400 is stopped will be described with reference to FIG. When the operation of the humidifier 400 stops, the pumping of the humidifying liquid LQ by the pump 421 stops. On the other hand, the humidifying liquid LQ stored in the water supply tank 407 and the humidifying liquid LQ above the branch joint 424 of the water supply pipe 422 are drained through the branch drain pipe 425 by their own weight. As shown in FIG. 5, the liquid level of the humidifying liquid LQ after the end of drainage is the height of the branch joint 424 located below the water supply tank 407 in the gravity direction. For this reason, when the humidifier 400 is stopped, the primary water supply roller 402 does not touch the humidifying liquid LQ, and rubber deterioration is prevented.

  Further, even when the humidifying device 400 is pulled out from the sheet wavy correction device 900 by jamming or the like, the humidifying liquid LQ does not accumulate in the water supply tank 407, so that the humidifying liquid LQ does not spill and contamination or failure in the device. Can be prevented.

  When the humidifying device 400 is operated again, the water supply tank 407 can be filled with the humidifying liquid LQ before starting the humidifying operation by operating the pump 421 during the startup time of the printer 500.

  Since drainage from the water supply tank 407 is performed by the weight of the humidifying liquid LQ, the operator of the apparatus does not need to perform any operation for drainage. Further, it is not necessary to add a solenoid valve for switching the flow path, a pump for draining, or the like, and drainage from the water supply tank 407 is possible with a simple and inexpensive configuration.

  In the present embodiment, since the flow rate adjustment valve 426 is provided, the amount of the humidified liquid drained through the branch drain pipe 425 can be easily set, and the recovery unit regardless of the diameter of the branch drain pipe 425. Can be configured.

  In the present embodiment, the branch drain pipe 425 is provided with the flow rate adjustment valve 426 to adjust the discharge amount of the humidified liquid via the branch drain pipe 425. However, a part of the humidified liquid LQ pumped up to the water supply tank 407 is always used. The structure which drains a fixed amount is not limited to this. For example, a branch drain pipe 425 that is thinner than the water supply pipe 422 may be used, and a desired discharge amount may be obtained without providing the flow rate adjustment valve 426.

LQ: humidifying liquid 100: fixing device 101, 201, 301 ... sheet tension conveying device 400 ... humidifying device 401 ... humidifying roller 402 ... primary water supply roller 403 ... secondary water supply roller 404 ... first regulating roller 405 ... second regulating roller 407 ... Water tank 409 ... Water inlet 410 ... Water tank drain 411 ... Water tank drain pipe 412 ... Drain groove 413 ... Drain port 420 ... Water storage tank 421 ... Pump 422 ... Water pipe 423 ... Drain pipe 424 ... Branch joint 425 ... Branch drain Pipe 426 ... Flow rate adjustment valve 510 ... Image forming unit 600 ... Curl correction device 900 ... Sheet waviness correction device

Claims (10)

In a sheet humidifier for humidifying a conveyed sheet,
A supply member for supplying a humidifying liquid to the sheet;
A holding unit for holding the humidifying liquid so that a part of the supply member is immersed in the humidifying liquid;
An accommodating portion for accommodating the humidifying liquid;
A supply unit that supplies the humidifying liquid stored in the storage unit to the holding unit;
A discharge unit for returning the humidified liquid overflowed from the holding unit to the storage unit;
A collection unit for collecting the humidifying liquid held in the holding unit into the storage unit by natural discharge;
Have
When the humidifying liquid is no longer supplied from the housing part to the holding part and the humidifying liquid held in the holding part is recovered from the recovery part, the liquid level of the humidifying liquid in the holding part is the lowest part of the supply member A sheet humidifier characterized by a lower position. The flow rate of the humidifying liquid discharged through the recovery unit is
The sheet humidification according to claim 1, wherein the sheet humidification is smaller than an amount obtained by subtracting an amount of the humidifying liquid supplied from the holding unit to the supply member from a flow rate of the humidifying liquid supplied to the holding unit by the supply unit. apparatus.   3. The sheet according to claim 1, wherein the collection unit is provided with a discharge port for discharging the humidifying liquid from the holding unit at a position lower than a lowermost part of the supply member. Humidifier. The discharge part has a receiving part for receiving the humidified liquid overflowed from the holding part,
The sheet humidifier according to any one of claims 1 to 3, wherein the recovery unit discharges the humidifying liquid to the receiving unit.   The collection unit is provided to be branched to a supply path through which the humidifying liquid is supplied from the storage unit to the holding unit, and is configured to communicate with the supply path and the discharge path of the discharge unit. The sheet humidifying device according to any one of claims 1 to 3.   The sheet humidifier according to claim 5, wherein the recovery unit includes a flow rate adjusting unit capable of adjusting a discharge amount. In a sheet humidifier for humidifying a conveyed sheet,
A roller for supplying a humidifying liquid to the sheet;
A humidifying tank for holding a humidifying liquid having an upper opening so that a part of the roller is immersed in the humidifying liquid;
A tank containing the humidifying liquid;
A pump for supplying the humidifying liquid stored in the tank to the humidifying tank;
A discharge part for returning the humidified liquid overflowed from the opening of the humidifying tank to the tank;
A discharge port provided in a humidification tank for naturally discharging a humidified liquid from the humidification tank, the discharge port provided at a position lower than the lowest part of the supply humidification roller;
A sheet humidifying device comprising: In a sheet post-processing apparatus that processes an image-formed sheet,
The sheet humidifying device according to any one of claims 1 to 6, for humidifying the sheet;
A processing unit for processing the sheet humidified by the sheet humidifying device;
A sheet post-processing apparatus.   The sheet post-processing apparatus according to claim 8, wherein the processing unit is a curl correction apparatus that corrects a curl of the sheet. An image forming unit for forming an image on a sheet;
The sheet post-processing apparatus according to claim 8 or 9, for post-processing the image-formed sheet;
An image forming apparatus.