JP2015191080A - Liquid application device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for applying a humidifying agent to a recording material after a fixation process, the device being a liquid application device that can prevent a decrease in the amount of application due to an increase in temperature of the humidifying agent to control the amount of application of the humidifying agent constant.SOLUTION: A liquid application device includes a temperature detection sensor 331 that detects the temperature of a liquid (humidifying agent) to be supplied to an application roller 31, and a pump 36 that causes circulation of the liquid from a liquid supply port 332 communicating with the inside of a liquid holding space 7 to a liquid recovery port 333 communicating with the inside of the liquid holding space 7, and controls the pump 36 so as to decrease the flow rate of the liquid inside the liquid holding space 7 as the temperature of the liquid detected by the temperature detection sensor 331 increases.

Description

  The present invention relates to a liquid coating apparatus and an image forming apparatus including the same.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic system, a fixing device is used to fix and fix a toner image electrostatically formed on a recording material made of paper or the like on the recording material. This fixing device includes a fixing roller heated by a heater and a pressure roller that is also heated and pressed against the fixing roller. A recording material on which a toner image is electrostatically formed is passed through a pressure nip formed by these two rollers, and the toner image is fixedly fixed to the recording material. This type of fixing device has advantages such as high thermal efficiency, excellent safety, and miniaturization, and is widely used.

  In such a fixing step, heat is applied to the toner and the recording material. For this reason, moisture inside the recording material evaporates when passing through the press nip and after passing through the press nip. Due to such a change in the moisture content of the recording material, the recording material is wavy and curled.

  When the recording material made of paper is seen at the fiber level, the recording material is composed of short fibers entangled with each other, moisture is contained inside or between the fibers, and the fibers and water form hydrogen bonds. . Cellulose has a number of hydroxyl groups, and has the property of attracting other hydrogen atoms depending on the polarity of the hydroxyl groups. Therefore, if water is contained between the fibers, hydrogen bonds are formed between the fibers and the water.

  When heat is applied to the recording material in the fixing process, the moisture inside the recording material evaporates, and the cellulose that has been hydrogen bonded to water hydrogen bonds to the hydroxyl groups of other cellulose instead of water molecules, Deformation occurs. Hydrogen bonding occurs between the fibers, and the recording material is deformed.

  If the recording material after the fixing process is left unattended, it absorbs moisture from the environment and the hydrogen bonds between the fibers are separated again. However, there is no moisture between some of the fibers, thereby maintaining the deformation of the recording material.

  There are two types of deformation patterns of the recording material after the fixing process: one that deforms due to expansion / contraction difference between the center and end of the recording material (waving) and one that deforms due to expansion / contraction difference between the front and back of the recording material (curl). . These deformations cause undulations and curls in the recording material.

  It has been proposed that the recording material after the fixing process is humidified as a means for solving the occurrence of undulation and curling of the recording material after the fixing process. For example, Patent Document 1 proposes a liquid application apparatus that applies moisture to a recording material, and applies a liquid held in a liquid holding space to the recording material via an application roller. By applying moisture to the recording material, the moisture taken away by heat and pressure in the fixing process is replenished, and undulation and curling are reduced.

  This reduction in waviness and curl is considered to be caused by the following two factors. One of them is that as the moisture content of the recording material increases, the Young's modulus of the recording material itself decreases and the stiffness decreases. Second, it is considered that waving and curling are reduced by water entering the gaps between the fibers of the sheet and detaching the bonds between the hydrogen-bonded fibers once by the fixing device.

  In such a configuration, since the liquid holding space is set to a negative pressure, evaporation and leakage of the liquid can be prevented, and since the configuration is relatively simple, there is an advantage that moisture application can be realized in a small space. .

  In particular, since this configuration is small, even in a case where the main body space is limited in an image forming apparatus such as a printer, it is possible to easily realize moisture application to the recording material after the fixing process. .

JP 2008-168283 A

  However, when the liquid application apparatus described in Patent Document 1 is mounted as a humidifying agent application apparatus after the fixing process, the surface of the application roller that contacts the recording material heated in the fixing process is heated. Along with this, the viscosity of the humidifying agent in the liquid holding space decreases, a liquid film having a sufficient thickness cannot be formed on the surface of the application roller, and the amount of the humidifying agent applied decreases. This occurs remarkably during continuous passage where the heated recording material continuously contacts the application roller.

  The present invention solves the above-described problems, and an object of the present invention is to prevent a decrease in the coating amount due to the temperature rise of the liquid and to control the liquid coating amount to be constant. Is to provide.

  In order to achieve the above object, a typical configuration of a liquid application apparatus according to the present invention includes an application member for applying a liquid to a medium, and a liquid in a liquid holding space formed in contact with the application member. A liquid holding member that holds the liquid, and a temperature detecting unit that detects the temperature of the liquid in a liquid application device that applies the liquid in the liquid holding space to the medium by rotating the application member; Liquid flowing means for causing the liquid to flow from a liquid supply port communicating with the liquid holding space to a liquid recovery port communicating with the liquid holding space, and the liquid detected by the temperature detecting means Control means for controlling the liquid flow means so that the higher the temperature of the liquid, the lower the flow rate of the liquid generated in the liquid holding space. And features.

  According to the above configuration, it is possible to prevent the application amount from being reduced due to the temperature rise of the liquid and to control the application amount of the liquid to be constant.

1 is an explanatory cross-sectional view illustrating a configuration of an image forming apparatus including a liquid coating apparatus according to the present invention. FIG. 3 is an explanatory cross-sectional view illustrating a configuration of a fixing unit provided in the image forming apparatus. It is a section explanatory view showing the composition of the liquid application device concerning the present invention. It is a schematic explanatory drawing which shows the structure of the liquid flow means to flow the liquid in the liquid holding space. It is a block diagram which shows the structure of the control system of the liquid coating device which concerns on this invention. It is a figure which shows the change of the temperature of the application member when the recording material after a fixing process passes continuously, and the temperature of the liquid in the liquid holding space. It is a figure which shows the relationship between the flow velocity of the liquid in the liquid holding space, and the pressure in the holding space of the liquid. The liquid flow rate in the liquid holding space when the temperature of the liquid in the liquid holding space is 20 ° C., 40 ° C., and 60 ° C., and the amount of liquid applied to the A3 size recording material by the application member It is a figure which shows a relationship. 4 is a flowchart showing a state in which the flow rate of the liquid in the liquid holding space is controlled in accordance with the temperature of the liquid in the liquid holding space in the first embodiment of the liquid application apparatus according to the present invention. It is a figure which shows an example of the component of a liquid. (A) is a figure explaining the ripple reduction effect of the recording material in a comparative example. (B) is a figure explaining the wavy reduction effect of the recording material in 1st Embodiment. (C) is a figure explaining the wavy reduction effect of the recording material in 2nd Embodiment. The relationship between the rotation speed of the application member when the temperature of the liquid in the liquid holding space is 20 ° C., 40 ° C., and 60 ° C. and the application amount of the liquid applied to the A3 size recording material by the application member is shown. FIG. It is a flowchart which shows a mode that the rotational speed of an application member is controlled according to the temperature of the liquid in the liquid holding space in 2nd Embodiment of the liquid application apparatus which concerns on this invention.

  An embodiment of an image forming apparatus provided with a liquid coating apparatus according to the present invention will be specifically described with reference to the drawings.

  First, the configuration of a first embodiment of an image forming apparatus provided with a liquid coating apparatus according to the present invention will be described with reference to FIGS. FIG. 1 shows a configuration of an image forming apparatus 3 using an electrophotographic system.

  In FIG. 1, the image forming apparatus 3 is provided with a fixing device 20 as a fixing unit shown in FIG. The fixing device 20 is provided with a fixing roller 21 serving as a fixing member. Further, a pressure roller 22 serving as a pressure member is provided. Then, a recording material P that is a medium carrying the unfixed toner image 8 is passed through a fixing nip portion N that is a pressure contact portion between the fixing roller 21 and the pressure roller 22. Thereby, the heat fixing process is performed by heat and pressure.

  Further, the image forming apparatus 3 is provided with a liquid application device 30 shown in FIG. The liquid applying device 30 applies a humidifying agent L that becomes a liquid to the recording material P that has been heat-fixed by the fixing device 20.

  As shown in FIG. 4, the humidifying agent L is placed in the liquid holding space 7 (in the liquid holding space) formed in contact with the application roller 31 that is an application member for applying the humidifying agent L to the recording material P. A liquid holding member 33 for holding is provided in the liquid application device 30. In the present embodiment, by reducing the circulation flow rate of the humidifying agent L generated in the liquid holding space 7, the application amount of the humidifying agent L is reduced as the recording material P heat-fixed by the fixing device 20 is heated. In this way, the application amount of the humidifying agent L to the recording material P is kept constant.

<Image forming apparatus>
First, the configuration of the image forming apparatus 3 will be described with reference to FIG. In FIG. 1, the image forming apparatus 3 of the present embodiment includes an image forming unit 10 serving as an image forming unit that forms an unfixed toner image 8 on a recording material P. Further, the image forming apparatus includes a fixing device 20 that performs a heat fixing process and a liquid application device 30 that applies a humidifying agent L (water) to the recording material P in which water has evaporated in the heat fixing process.

<Image forming unit>
In the image forming unit 10, a toner image is formed on the surface of the photosensitive drum 11 serving as an image carrier by an image forming process. A transfer belt 12 serving as an intermediate transfer member is provided adjacent to the photosensitive drum 11. The toner image formed on the surface of the photosensitive drum 11 is primarily transferred onto the outer peripheral surface of the transfer belt 12 by applying a primary transfer bias voltage to a primary transfer roller 15 serving as a primary transfer unit.

  The primary transfer toner image primarily transferred onto the outer peripheral surface of the transfer belt 12 is secondarily transferred onto the recording material P by applying a secondary transfer bias voltage to a secondary transfer roller 17 serving as a secondary transfer unit. The

  On the outer periphery of the photosensitive drum 11, a charger 13 as a charging unit, a developing device 14 as a developing unit, a primary transfer roller 15, and a cleaner 16 as a cleaning unit are provided. In addition, a laser scanner 19 serving as an image exposure unit including a light source device and a polygon mirror is provided above the image forming apparatus 3.

  The laser scanner 19 scans the laser light emitted from the light source device by rotating a polygon mirror, and condenses the light beam 19a of the scanning light on the surface of the photosensitive drum 11 by a mirror or the like for exposure. As a result, an electrostatic latent image corresponding to the image signal is formed on the surface of the photosensitive drum 11 uniformly charged by the charger 13.

  The developing device 14 is filled with a predetermined amount of toner as a developer by a developer container (not shown). The developing device 14 supplies toner to the electrostatic latent image on the surface of the photosensitive drum 11, develops it as a toner image, and visualizes it. The toner image formed on the surface of the photosensitive drum 11 is superimposed and transferred onto the outer peripheral surface of the transfer belt 12 that rotates in synchronization with the photosensitive drum 11 by the action of the primary transfer roller 15.

  The secondary transfer roller 17 is axially supported in parallel with the transfer belt 12 and is disposed in contact with the outer peripheral surface of the transfer belt 12. A predetermined secondary transfer bias voltage is applied to the secondary transfer roller 17 by a secondary transfer bias power source (not shown). As a result, the toner image superimposed and transferred onto the outer peripheral surface of the transfer belt 12 is secondarily transferred to the recording material P conveyed to the nip portion between the transfer belt 12 and the secondary transfer roller 17.

  On the other hand, the recording material P accommodated in the feeding cassette 1 is separated and fed one by one by a feeding roller and a separating member (not shown) in synchronization with image formation by the image forming unit 10. Thereafter, the skew is corrected by the registration roller 2, and then passed through a pre-transfer guide (not shown) and conveyed to a secondary transfer portion formed by a nip portion between the transfer belt 12 and the secondary transfer roller 17. Then, by applying a secondary transfer bias voltage to the secondary transfer roller 17, the toner image formed on the outer peripheral surface of the transfer belt 12 is secondarily transferred to the recording material P and unfixed on the recording material P. A toner image 8 is formed.

  The toner remaining on the surface of the photosensitive drum 11 after the primary transfer is removed and collected by the cleaner 16, and subsequently used for the next image formation. Further, toner and other foreign matters remaining on the outer peripheral surface of the transfer belt 12 are removed and collected by a belt cleaner 18 serving as a cleaning unit.

<Fixing part>
Next, the configuration of the fixing device 20 will be described with reference to FIG. FIG. 2 is an explanatory cross-sectional view showing the configuration of the fixing device 20. In FIG. 2, the fixing device 20 includes a fixing roller 21 having a halogen heater 23a serving as a heating unit and a pressure roller 22 having a halogen heater 23b therein. Further, the image forming apparatus includes a cleaning web 24 serving as a cleaning unit for cleaning the fixing roller 21, a separation claw 25 for separating the recording material P after fixing from the surface of the fixing roller 21, and the like.

  The fixing roller 21 has a silicon (Si) rubber layer of about 12 mm as an intermediate layer on an aluminum (Al) hollow core metal having an outer diameter of 50 mm and a thickness of 12 mm. A surface layer is formed by coating the outer peripheral surface of the silicon (Si) rubber layer with a fluororesin such as PTFE (Polytetrafluoroethylene) to about 20 μm.

  The pressure roller 22 has a silicon rubber layer having a thickness of 25 μm on an aluminum (Al) hollow core metal having an outer diameter of 50 mm and a thickness of 12 mm. The surface layer of the pressure roller 22 covers a PFA (tetrafluoroethylene / perfluoroalkyl ether copolymer) tube of about 50 μm.

  The thermistors 26a and 26b for detecting the temperature of the rollers are in contact with the passage regions of the recording material P on the surfaces of the fixing roller 21 and the pressure roller 22, respectively. Based on the temperature detected by the thermistors 26a and 26b, the temperature controller 27 controls the outputs of the halogen heaters 23a and 23b. At the time of heat fixing, the fixing roller 21 is controlled to be kept at about 180 ° C., and the pressure roller 22 is kept at about 90 ° C.

  The maximum output during image formation of the halogen heaters 23a and 23b is 1000 W, and 50 sheets of A3 size recording material P can be passed per minute. The rotation speed of the fixing roller 21 is controlled to 300 mm / sec, and the pressure roller 22 rotates following the fixing roller 21.

  As shown in FIG. 2, a fixing nip portion N is formed by press-contacting the pressure roller 22 and the fixing roller 21. The unfixed toner image 8 formed on the recording material P formed by the image forming unit 10 is heated and pressurized by passing through the fixing nip portion N to be fixed. In this embodiment, the width of the fixing nip portion N in the recording material conveyance direction (left-right direction in FIG. 2) is set to 6 mm.

  The cleaning web 24 is made of a nonwoven fabric such as polyamide having a thickness of about 50 μm. The cleaning web 24 is impregnated with silicon oil having a viscosity of 10,000 cs (centistokes). The cleaning web 24 is wound up in a direction against the rotation of the fixing roller 21 by the winding roller 4 while being pressed against the outer peripheral surface of the fixing roller 21 by the pressing roller 9.

  In order to reduce the replacement frequency of the cleaning web 24 for the purpose of reducing the running cost, the winding speed of the cleaning web 24 is set extremely slow as about 0.05 mm per recording material P. During normal printing, the effect of cleaning the outer peripheral surface of the fixing roller 21 can be sufficiently exerted. For the feeding operation of the cleaning web 24, the take-up roller 4 is rotated via the one-way clutch. One end of an arm provided in the one-way clutch is operated by a solenoid magnet. As a result, the cleaning web 24 can be stably fed in a small amount.

<Liquid application part>
Next, the configuration of the liquid application device 30 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional explanatory view showing the configuration of the liquid application device 30. The liquid application device 30 includes a liquid application unit 40 serving as a liquid application unit that applies the humidifying agent L to the recording material P, and a liquid supply unit 50 serving as a liquid supply unit that supplies the humidifying agent L to the liquid application unit 40. It is comprised. The liquid application unit 40 includes a cylindrical application roller 31, a cylindrical counter roller 32 disposed opposite to the application roller 31, and roller drive control serving as a control unit that controls the rotation drive of the application roller 31. Part 34 and the like.

  The counter roller 32 is urged toward the peripheral surface of the application roller 31 by urging means (not shown). The application roller 31 is rotated in the clockwise direction in FIG. As a result, the recording material P to which the humidifying agent L is to be applied can be sandwiched and conveyed between the application roller 31 and the counter roller 32. The recording material P is sandwiched between the application roller 31 and the counter roller 32, and the humidifying agent L adhering to the outer peripheral surfaces of the application roller 31 and the counter roller 32 is transferred and applied in the left direction indicated by the arrow in FIG. Be transported. The liquid application device 30 of this embodiment applies the humidifying agent L in the liquid holding space 7 to the recording material P by rotating the application roller 31.

  In this embodiment, the material of the application roller 31 is made of silicon rubber having a rubber hardness of 20 degrees, and the diameter is 25 mm. The counter roller 32 is made of iron and has a diameter of 15 mm.

  Further, the liquid supply unit 50 supplies the humidifying agent L into the liquid holding space 33 of the liquid holding member 33 and the liquid holding member 33 that holds the humidifying agent L between the outer peripheral surface of the application roller 31 and FIG. The liquid flow paths 35a to 35c shown in FIG.

  The liquid holding member 33 is urged against the outer peripheral surface of the application roller 31 by the urging force of the spring member 5, and the contact member 334 is in contact with the outer peripheral surface of the application roller 31. The liquid holding member 33 is formed with a long liquid holding space 7 provided over the entire application region of the humidifying agent L by the application roller 31. In the liquid holding space 7, a temperature detection sensor 331 configured by a thermistor or the like serving as a temperature detection means for detecting the temperature of the humidifying agent L is provided.

  As shown in FIG. 4, the liquid holding member 33 is provided with a liquid supply port 332 and a liquid recovery port 333 each having a through hole communicating with the liquid holding space 7 holding the humidifying agent L. Yes. The liquid supply port 332 supplies the humidifying agent L supplied from the liquid channel 35 a into the liquid holding space 7. The liquid recovery port 333 causes the humidifying agent L in the liquid holding space 7 to flow out to the liquid flow path 35b.

  A closed channel 28 is formed by the buffer tank 37 in which the humidifying agent L is stored, the liquid channels 35a to 35c, the liquid supply port 332, the liquid holding space 7, and the liquid recovery port 333. Humidifier L circulates. A pump 36 serving as a liquid flow means is provided in the liquid flow paths 35b and 35c between the liquid recovery port 333 and the buffer tank 37. The pump 36 causes the humidifying agent L to flow from the liquid supply port 332 communicating with the liquid holding space 7 to the liquid recovery port 333 communicating with the liquid holding space 7.

  By supplying and outflowing the humidifying agent L into the liquid holding space 7 by the pump 36, the humidifying agent L in the liquid holding space 7 flows from the left side to the right side indicated by the arrow in FIG. The pump 36 forcibly causes the humidifier L and air to flow in the direction of the buffer tank 37 in the liquid flow path 35. Thus, the humidifying agent L is supplied into the liquid holding space 7 from the buffer tank 37 in which the humidifying agent L is stored using the pump 36 through the liquid channel 35a.

  A circulation flow rate control unit 38 serving as a control means for controlling the pump 36 controls the rotational drive of the pump 36 based on the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. The humidifying agent L circulates in the closed flow path 28 that connects the liquid holding space 7 of the liquid holding member 33 and the buffer tank 37 through the liquid flow paths 35a to 35c by the rotational drive of the pump 36. By controlling the rotational drive of the pump 36 by the circulation flow rate control unit 38, the flow rate of the humidifying agent L flowing in the liquid holding space 7 from the liquid supply port 332 side to the liquid recovery port 333 side is controlled.

  The buffer tank 37 is provided with a communication port 371 that communicates with the atmosphere. For this reason, the inside of the liquid holding space 7 connected by the liquid flow paths 35a to 35c has a negative pressure. As a result, the humidifying agent L in the liquid holding space 7 does not leak to the outside and stain the inside of the image forming apparatus 3 main body.

<Application operation>
As shown in FIG. 3, when the application roller 31 rotates, the humidifying agent L held in the liquid holding space 7 resists the pressing force of the contact member 334 of the liquid holding member 33 against the application roller 31. The contact portion M between the roller 31 and the contact member 334 passes through. Then, it adheres to the outer peripheral surface of the application roller 31 in a layered state. The humidifying agent L adhering to the outer peripheral surface of the application roller 31 is sent to the contact portion 29 between the application roller 31 and the counter roller 32.

  Next, the recording material P that has passed through the fixing device 20 is conveyed to the contact portion 29 between the application roller 31 and the counter roller 32. Then, it is inserted between the application roller 31 and the counter roller 32. Then, the sheet is sandwiched between the application roller 31 and the counter roller 32 and conveyed toward the discharge unit 6 in FIG. The humidifying agent L applied to the outer peripheral surface of the application roller 31 during this conveyance is transferred from the application roller 31 to the recording material P.

  After the humidifying agent L is applied to the recording material P by the liquid applying device 30, it is conveyed leftward as indicated by the arrow in FIG.

<Humidifier>
The humidifier L used in the present embodiment supplies moisture to the recording material P after the heat fixing step by the fixing device 20. As a result, a liquid intended to prevent the recording material P from wavy or curled is applied. An example of the component of the humidifying agent L of this embodiment is shown in FIG. The viscosity of the humidifier L is 5 cP (centipoise) to 6 cP (centipoise) at 25 ° C.

  When water is used as the humidifying agent L (liquid) applied to the recording material P as in this embodiment, the slidability between the application roller 31 and the contact member 334 of the liquid holding member 33 is determined by the surface tension. It becomes favorable by including the component to lower in the humidifier L (liquid). Therefore, in the example of the component of the humidifying agent L of the present embodiment shown in FIG. 10, a surfactant is included as a component that lowers the surface tension of the humidifying agent L.

  The surfactant is a substance having a hydrophilic group and a hydrophobic group, and has a function of uniformly mixing a polar substance and a nonpolar substance by forming a micelle, a vesicle, or a lamella structure. Further, the surfactant has an action of weakening the surface tension. An example of the surfactant is an ionic surfactant acetylene glycol.

  Further, in order to form a sufficiently thick liquid film of the humidifying agent L on the surface of the application roller 31, the humidifying agent L needs to have a sufficient viscosity. Therefore, in the example of the component of the humidifying agent L of the present embodiment shown in FIG. 10, glycerin is included as a component that imparts viscosity to the humidifying agent L.

  Further, when the humidifying agent L (liquid) is applied to the recording material P for the purpose of preventing the recording material P from being wavy or curled after the heat fixing step by the fixing device 20 as in the present embodiment, the applied moisture Preferably remains in the recording material P for a long time. Therefore, in the example of the component of the humidifying agent L of the present embodiment shown in FIG. 10, a deliquescent substance is included as a component that imparts a moisturizing action.

  Deliquesce is a phenomenon in which a substance takes in water vapor in the air and spontaneously becomes an aqueous solution. Magnesium chloride, L-carnitine, and N-methylglycine can be used as the deliquescent material. Furthermore, BtEAC (Benzyl triethyl ammonium chloride) can be applied. Furthermore, N-methylmorpholine-N-oxide, BtMAC (Benzyl trimethyl ammonium chloride), choline chloride, etc. can be applied.

<Comparative example>
Here, as a comparative example, regardless of the temperature Tl of the humidifying agent L, the circulation flow rate of the humidifying agent L in the liquid holding space 7 is constant at 200 g / min. Further, the rotation speed of the outer peripheral surface of the application roller 31 is constant at 375 mm / sec. Then, 1000 A3-sized recording materials P made of paper are continuously printed. FIG. 11A shows the result of the waviness level of the recording material P in that case. The conveyance speed of the recording material P is constantly controlled at 375 mm / sec, which is the rotational speed of the outer peripheral surface of the application roller 31, and the A3 size recording material P is changed to the preceding recording material P and the subsequent recording material P. The pitch interval was controlled to 30 mm, and 50 recording materials P were passed every minute.

  FIG. 6 is a diagram showing the relationship between the temperature Tr of the application roller 31 when the recording material P made of paper is continuously printed and the temperature Tl of the humidifying agent L in the liquid holding space 7. As shown in FIG. 6, the application roller 31 having a temperature Tr of 20 ° C. at the start of printing continuously contacts the recording material P heated in the heat fixing step by the fixing device 20. As a result, the temperature Tr of the application roller 31 is increased to 60 ° C. at the 500th sheet of the recording material P, and the temperature Tr of the application roller 31 is increased to 80 ° C. at the 1000th sheet of the recording material P.

  As shown in FIG. 6, the humidifying agent L in the liquid holding space 7 had a temperature Tl of 15 ° C. at the start of printing. After that, under the influence of the temperature rise of the application roller 31 that is continuously in contact with the recording material P heated in the heat fixing step by the fixing device 20, the humidifying agent L in the liquid holding space 7 of the 500th recording material P is removed. The temperature Tl was raised to 35 ° C. Further, the temperature Tl of the humidifying agent L in the liquid holding space 7 increased to 60 ° C. on the 1000th sheet of the recording material P.

  In FIG. 11A, in this comparative example, A3-sized recording material P made of paper was continuously printed. In this case, the temperature Tl of the humidifying agent L in the liquid holding space 7 at the start of printing (the 0th sheet of the recording material P), the 500th sheet of the recording material P, and the 1000th sheet of the recording material P is shown. Furthermore, the application amount (g / A3) of the humidifying agent L applied to the recording material P per A3 size sheet is shown. Further, the waviness level (waving height mm) of the recording material P is shown. As shown in FIG. 11 (a), it can be seen that the application amount of the humidifying agent L decreases and the waviness level deteriorates in the latter half of the continuous passage.

  As shown in FIG. 6, the viscosity of the humidifying agent L decreases with an increase in the temperature of the humidifying agent L in the liquid holding space 7, and the humidifying agent L having a sufficient thickness on the outer peripheral surface of the application roller 31. This is because the liquid film cannot be formed. That is, in the comparative example shown in FIG. 11A, the application amount of the humidifying agent L applied to the outer peripheral surface of the application roller 31 during continuous printing decreases. For this reason, the waviness of the recording material P cannot be reduced.

  In the present embodiment, the following control is performed based on the temperature Tl (temperature result) of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. The rotational flow rate control unit 38 controls the rotational driving of the pump 36 so that the flow rate of the humidifying agent L generated in the liquid holding space 7 decreases as the temperature Tl of the humidifying agent L in the liquid holding space 7 increases. Accordingly, the negative pressure in the liquid holding space 7 is adjusted so that the amount of the humidifying agent L applied to the recording material P is kept constant.

  Here, the application amount of the humidifying agent L applied to the recording material P can be changed by changing the circulation flow rate of the humidifying agent L in the liquid holding space 7 with reference to FIGS. The principle will be described. FIG. 7 is a diagram showing the relationship between the pressure in the liquid holding space 7 and the circulation flow rate (flow rate) of the humidifying agent L in the liquid holding space 7.

  FIG. 8 shows the circulation flow rate (flow rate) of the humidifying agent L in the liquid holding space 7 when the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 20 ° C., 40 ° C., and 60 ° C. Furthermore, it is a figure which shows the relationship with the application quantity of the humidifying agent L apply | coated to the recording material P per A3 size sheet.

  As shown in FIG. 7, the higher the circulation flow rate of the humidifying agent L in the liquid holding space 7, the lower the pressure in the liquid holding space 7. As the pressure in the liquid holding space 7 decreases, the amount of the humidifying agent L that passes through the contact portion M between the application roller 31 and the contact member 334 shown in FIG. 3 decreases. As a result, the amount of the humidifying agent L applied to the outer peripheral surface of the application roller 31 is reduced. For this reason, the application amount of the humidifying agent L applied to the recording material P is reduced.

  As shown in FIG. 8, the faster the circulation flow rate of the humidifying agent L in the liquid holding space 7, the smaller the amount of the humidifying agent L applied to the outer peripheral surface of the applying roller 31, and the humidifying agent applied to the recording material P. It turns out that the application quantity of L decreases. This is presumably due to the following reasons.

  The higher the circulation flow rate of the humidifying agent L in the liquid holding space 7, the lower the pressure in the liquid holding space 7. When the pressure in the liquid holding space 7 becomes low, the outer surface of the application roller 31 shown in FIG. 3 is sucked toward the liquid holding space 7. As a result, the contact pressure of the contact member 334 provided on the liquid holding member 33 against the outer surface of the application roller 31 increases.

  As a result, the contact area of the contact portion M between the contact member 334 and the outer surface of the application roller 31 is increased, and the gap between the contact portions M is reduced. For this reason, it becomes difficult for the humidifier L to pass through the contact portion M.

  Thus, the flow rate of the humidifying agent L generated in the liquid holding space 7 is changed (increased or decreased). As a result, the gap state of the contact portion M between the contact member 334 provided on the liquid holding member 33 and the outer surface of the application roller 31 changes. As a result, the amount of the humidifying agent L that passes through the gap of the corresponding contact portion M from the liquid holding space 7 and changes.

  The circulation flow rate of the humidifying agent L in the liquid holding space 7 is used as a parameter. At that time, as shown in FIG. 8, the application amount of the humidifying agent L to the outer peripheral surface of the applying roller 31 is changed by the circulation flow rate (g / min) of the humidifying agent L in the liquid holding space 7. Thereby, the application amount of the humidifying agent L applied to the recording material P can be controlled.

  FIG. 5 is a block diagram showing the configuration of the control system of the liquid application device 30. A temperature detection sensor 331 serving as a temperature detection unit for detecting the temperature Tl of the humidifying agent L in the liquid holding space 7 is connected to the circulation flow rate control unit 38 and the roller drive control unit 34 serving as control units.

  A pump drive motor 361 that drives a pump 36 that circulates the humidifying agent L in the liquid holding space 7 is connected to the circulation flow rate control unit 38 that is a control means of the present embodiment via a drive circuit 381. Further, a roller drive motor 311 for rotating the application roller 31 is connected to a roller drive control unit 34 serving as a control unit of the second embodiment described below via a drive circuit 341.

  The circulation flow rate control unit 38 and the roller drive control unit 34 serving as control means are configured to have a CPU (Central Processing Unit). The CPU has a ROM (Read Only Memory) serving as storage means inside. The ROM stores a program corresponding to a predetermined control procedure. The CPU controls each unit while reading this program.

  The CPU also has a RAM (Randon Access Memory) serving as a storage means in which work data and input data are stored. The CPU performs control with reference to data stored in the RAM based on the above-described program and the like.

  The RAM stores a preset temperature-output table for controlling the output of the pump drive motor 361 corresponding to the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. ing. By controlling the output of the pump drive motor 361, the circulating flow rate (g / min) of the humidifying agent L in the liquid holding space 7 is controlled.

  Further, the RAM outputs a preset output of the roller drive motor 311 corresponding to the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 described in the second embodiment below. A temperature-output table for control is stored. The rotation speed of the application roller 31 is controlled by controlling the output of the roller drive motor 311.

  FIG. 9 is a flowchart showing the following control based on the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 in the liquid application apparatus 30 of the present embodiment. The rotational flow rate controller 38 controls the rotational drive of the pump 36 so that the circulation flow rate of the humidifying agent L generated in the liquid holding space 7 decreases as the temperature Tl of the humidifying agent L in the liquid holding space 7 increases. .

  In step S1 of FIG. 9, the circulating flow rate control unit 38 shown in FIG. 5 determines whether or not the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 20 ° C. or higher. To do. If the temperature Tl of the humidifying agent L in the liquid holding space 7 is lower than 20 ° C. in step S1, the process proceeds to step S2 to control the rotational drive of the pump 36 and circulate the humidifying agent L in the liquid holding space 7. Set the flow rate to 200 g / min.

  If the temperature Tl of the humidifying agent L in the liquid holding space 7 is 20 ° C. or higher in step S1, the process proceeds to step S3. 5 determines whether the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 40 ° C. or higher.

  In step S3, when the temperature Tl of the humidifying agent L in the liquid holding space 7 is lower than 40 ° C., the process proceeds to step S4, where the rotational drive of the pump 36 is controlled to circulate the humidifying agent L in the liquid holding space 7. Set the flow rate to 80 g / min.

  In step S3, when the temperature Tl of the humidifying agent L in the liquid holding space 7 is 40 ° C. or higher, the flow proceeds to step S5 to control the rotational drive of the pump 36 and the circulation flow rate of the humidifying agent L in the liquid holding space 7 Is set to 40 g / min.

  As shown in FIG. 9, the following control is performed based on the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. The rotational flow rate controller 38 controls the rotational drive of the pump 36 so that the circulation flow rate of the humidifying agent L generated in the liquid holding space 7 decreases as the temperature Tl of the humidifying agent L in the liquid holding space 7 increases. . Thereby, the application amount of the humidifying agent L to the recording material P can be kept at 0.40 (g / A3) via the applying roller 31 regardless of the temperature Tl of the humidifying agent L in the liquid holding space 7.

  In the present embodiment, it is formed between the liquid holding member 33 and the application roller 31 shown in FIG. 3 based on the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. The circulation flow rate of the humidifying agent L generated in the liquid holding space 7 is controlled. Thereby, the pressure in the liquid holding space 7 is controlled.

  As a result, the contact member 334 of the liquid holding member 33 changes the flow (movement) state of the humidifying agent L in the contact portion M that contacts the outer peripheral surface of the application roller 31. Thereby, the amount of the humidifying agent L attached to the application roller 31 and coming out from the contact portion M is controlled. Thus, the application amount of the humidifying agent L to the recording material P is controlled via the application roller 31.

  FIG. 11B is a table showing the waviness reduction effect of the recording material P in the present embodiment. A3 size recording material P made of paper is continuously printed. In this case, the following control is performed based on the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331.

  The circulation flow rate control unit 38 controls the pump drive motor 361 via the drive circuit 381 to change the circulation flow rate of the humidifying agent L in the liquid holding space 7 by the pump 36. As a result, the application amount of the humidifying agent L to the recording material P can be kept at 0.40 (g / A3) via the application roller 31. As a result, when the recording material P is continuously printed, the waviness of the recording material P by applying the humidifying agent L to the recording material P can be stably reduced.

  Next, the configuration of the second embodiment of the image forming apparatus provided with the liquid coating apparatus according to the present invention will be described with reference to FIGS. 1, 3, 5, 11 to 13. In addition, what was comprised similarly to the said 1st Embodiment attaches | subjects the same member name even if the same code | symbol or a code | symbol differs, and abbreviate | omits description.

  In the first embodiment, the following control is performed based on the temperature Tl (temperature result) of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. An example of controlling the rotational drive of the pump 36 by the circulation flow rate control unit 38 so that the flow rate of the humidifying agent L generated in the liquid holding space 7 becomes lower as the temperature Tl of the humidifying agent L in the liquid holding space 7 becomes higher. Explained.

  In the present embodiment, the following control is performed based on the temperature Tl (temperature result) of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. As the temperature Tl of the humidifying agent L in the liquid holding space 7 increases, the driving circuit 341 is driven by a roller drive control unit 34 serving as control means so that the moving speed (rotational speed) of the application roller 31 relative to the liquid holding member 33 is increased. The rotational drive of the roller drive motor 311 is controlled via

  By increasing the rotation speed of the application roller 31 shown in FIG. 3, a decrease in the application amount of the humidifying agent L accompanying the temperature increase of the application roller 31 in contact with the recording material P heated in the heat fixing process by the fixing device 20 is prevented. The amount of the humidifying agent L applied to the recording material P can be kept constant.

  In this embodiment, the configuration of the image forming unit 10, the fixing device 20, the liquid applying device 30 and the like in the image forming apparatus 3 shown in FIG. 1 is the same as that in the first embodiment, and the application amount of the humidifying agent L is the same. Only the method of keeping the constant is different from the first embodiment.

  In this embodiment, the roller drive control unit 34 controls the roller drive motor 311 via the drive circuit 341 based on the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. Thus, the rotation speed of the application roller 31 is changed. By changing the rotation speed of the application roller 31, the amount of the humidifying agent L applied to the recording material P can be changed.

  FIG. 12 shows the rotation speed of the application roller 31 when the temperature Tl of the humidifier L in the liquid holding space 7 is 20 ° C., 40 ° C., and 60 ° C., and the humidifier L for the A3-sized recording material P by the application roller 31. The relationship with the application amount of is shown. As shown in FIG. 12, it can be seen that as the rotational speed of the application roller 31 is increased, the amount of the humidifying agent L applied to the recording material P increases. This is presumably due to the following reasons.

  As shown in FIG. 3, when the application roller 31 rotates in the counterclockwise direction indicated by the arrow in FIG. 3, the humidifying agent L held in the liquid holding space 7 is caused by the flow resistance on the surface of the application roller 31. The application roller 31 moves in the rotation direction (counterclockwise direction in FIG. 3). Then, against the pressing force of the contact member 334 of the liquid holding member 33 against the application roller 31, the humidifying agent L held in the liquid holding space 7 is applied between the application roller 31 and the contact member 334. Sent to the contact M.

  That is, the higher the rotation speed of the application roller 31, the higher the moving speed of the humidifying agent L that moves integrally with the application roller 31 due to the flow resistance of the surface of the application roller 31, and the greater the drag on the contact portion M. Become. And when the drag to the contact part M increases, the displacement amount of the corresponding contact part M increases. For this reason, the amount by which the humidifying agent L slides out from the contact portion M increases. Thus, as shown in FIG. 12, the application amount of the humidifying agent L to the outer peripheral surface of the application roller 31 is controlled by changing the rotation speed (mm / sec) of the application roller 31. Thereby, the application amount of the humidifying agent L to the recording material P can be controlled.

  FIG. 13 is a flowchart for performing the following control based on the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 in this embodiment. As the temperature Tl of the humidifying agent L in the liquid holding space 7 increases, the roller drive control unit 34 causes the roller drive motor 311 to be rotated via the drive circuit 341 so that the rotation speed of the application roller 31 relative to the liquid holding member 33 is increased. Controls rotational drive.

  In step S11 of FIG. 13, the roller drive control unit 34 shown in FIG. 5 determines whether or not the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 20 ° C. or higher. .

  If the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is lower than 20 ° C. in step S11, the process proceeds to step S12. The roller drive controller 34 controls the roller drive motor 311 via the drive circuit 341 to set the rotation speed of the application roller 31 to 375 mm / sec.

  In step S11, when the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 20 ° C. or higher, the process proceeds to step S13. 5 determines whether or not the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 40 ° C. or higher.

  If the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 in step S13 is lower than 40 ° C., the process proceeds to step S14. The roller drive controller 34 controls the roller drive motor 311 via the drive circuit 341 to set the rotation speed of the application roller 31 to 500 mm / sec.

  In step S13, if the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331 is 40 ° C. or higher, the process proceeds to step S15. The roller drive controller 34 controls the roller drive motor 311 via the drive circuit 341 to set the rotation speed of the application roller 31 to 625 mm / sec.

  In the present embodiment, the following control is performed based on the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. As the temperature Tl of the humidifying agent L in the liquid holding space 7 increases, the roller drive control unit 34 causes the roller drive motor 311 to be rotated via the drive circuit 341 so that the rotation speed of the application roller 31 relative to the liquid holding member 33 is increased. Controls rotational drive. Thereby, the application amount of the humidifying agent L to the recording material P can be kept at 0.40 (g / A3) via the application roller 31 regardless of the temperature Tl of the humidifying agent L in the liquid holding space 7.

  In the present embodiment, the rotation speed of the application roller 31 is controlled based on the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331. Thereby, the amount of the humidifying agent L in the liquid holding space 7 adhering to the outer peripheral surface of the application roller 31 and coming out from the contact portion M is controlled. Thus, the amount of the humidifying agent L applied to the recording material P is controlled.

  FIG. 11C is a table showing the waviness reduction effect of the recording material P in the present embodiment. A3 size recording material P made of paper is continuously printed. In this case, the following control is performed based on the detection result of the temperature Tl of the humidifying agent L in the liquid holding space 7 detected by the temperature detection sensor 331.

  The roller drive control unit 34 shown in FIG. 5 controls the roller drive motor 311 via the drive circuit 341 to change the rotation speed of the application roller 31. As a result, the application amount of the humidifying agent L to the recording material P can be kept at 0.40 (g / A3) via the application roller 31. As a result, when the recording material P is continuously printed, the waviness of the recording material P by applying the humidifying agent L to the recording material P can be stably reduced.

  In the present embodiment, the maximum size of the recording material P that can be used in the image forming apparatus 3 is 13 inches (inch) × 19 inches (inch). Therefore, the separation distance between the fixing device 20 and the liquid application device 30 shown in FIG. 1 in the left-right direction in FIG. 1 is set to 60 cm. In this way, the separation distance between the fixing device 20 and the liquid application device 30 in the left-right direction in FIG. 1 is sufficiently separated.

  Thus, as in the present embodiment, the recording material caused by the difference in the conveying speed between the fixing device 20 and the liquid coating device 30 caused by the change in the rotation speed of the coating roller 31, that is, the conveying speed of the recording material P in the liquid coating device 30. P conveyance failure can be prevented.

  Further, in the present embodiment, the effect of reducing the undulation of the recording material P with respect to the comparative example is different from that of the first embodiment, except that the method of preventing the decrease in the application amount of the humidifying agent L is different from that of the first embodiment. It is the same. Other configurations are the same as those in the first embodiment, and the same effects can be obtained.

L: Humidifying agent (liquid)
Tl: Temperature (temperature of the humidifier in the liquid holding space)
7 Liquid holding space
36… Pump (liquid flow means)
331… Temperature detection sensor (temperature detection means)
332… Liquid supply port
333… Liquid recovery port

Claims (3)

An application member for applying a liquid to the medium;
A liquid holding member for holding liquid in a liquid holding space formed in contact with the application member;
With
In the liquid application apparatus for applying the liquid in the liquid holding space to the medium by rotating the application member,
Temperature detecting means for detecting the temperature of the liquid;
Liquid flow means for causing the liquid to flow from a liquid supply port communicating with the liquid holding space to a liquid recovery port communicating with the liquid holding space;
With
Control means for controlling the liquid flow means so that the flow rate of the liquid generated in the liquid holding space decreases as the temperature of the liquid increases, based on the temperature result of the liquid detected by the temperature detection means. When,
A liquid coating apparatus comprising: An application member for applying a liquid to the medium;
A liquid holding member for holding liquid in a liquid holding space formed in contact with the application member;
With
In the liquid application apparatus for applying the liquid in the liquid holding space to the medium by rotating the application member,
Having temperature detection means for detecting the temperature of the liquid;
Control means for controlling the rotation of the application member to increase the moving speed of the application member relative to the liquid holding member as the temperature of the liquid increases based on the temperature result of the liquid detected by the temperature detection means. When,
A liquid coating apparatus comprising: The medium is made of a recording material,
Fixing means for performing fixing processing by heat and pressure by passing the recording material carrying an unfixed toner image through a pressure contact portion between the fixing member and the pressure member;
The liquid coating apparatus according to claim 1, wherein a liquid is applied to the recording material fixed by the fixing unit.
An image forming apparatus comprising:

Images