JP2010082492A - Treatment liquid applicator and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment liquid applicator which can improve print quality and reduce cost by uniformly applying a treatment liquid for pretreatment to a record medium. <P>SOLUTION: In a treatment liquid applying part 14, a measuring roller 120 rotates to measure the treatment liquid 48, and the measured treatment liquid 48 is received by a first spreading roller 122 to be sequentially applied on a sheet P. The treatment liquid 48 remaining on the outer peripheral surface of the first spreading roller 122 is recoated on the sheet P through an intermediate roller 126 and a second spreading roller 124. If crepe unevenness is generated on the sheet P in the application by the first spreading roller 122, the downstream side second spreading roller 124 performs recoating of the treatment liquid 48 with a smaller amount than the first spreading roller 122 to effectively reduce the crepe unevenness. Only one expensive measuring roller 120 is used, which enables suppression of device cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a processing liquid coating apparatus that applies a processing liquid to a recording medium, and an image forming apparatus that includes the processing liquid coating apparatus that applies a processing liquid to a recording medium.

The image forming process of the ink jet printing system is roughly divided into the following steps.
(1) An ink condensing reaction liquid (hereinafter referred to as a processing liquid) is applied and dried to provide an ink receiving layer on the paper.
(2) After forming an image by ink jet, excess medium (water, etc.) in the ink is removed by means such as hot air drying.
(3) Fix the color material on the paper by means of heat, pressure, or the like.

  Among these, it is very important to apply the treatment liquid uniformly in the step (1) without unevenness. This is because, when unevenness occurs in the application of the processing liquid, when ink is ejected in the step (2), the difference in the concentration of ink occurs due to the difference in the concentration of the processing liquid, resulting in a difference in image density. This is because. Further, it is a problem because the unevenness of the treatment liquid is visually recognized as the gloss unevenness of the paper as it is even in a place where the ink is not ejected. Therefore, it is extremely important to apply the treatment liquid without unevenness in order to ensure print quality.

By the way, there are generally “normal rotation application” and “reverse application” as a method of applying a liquid to a roller.
“Forward rotation application” is a method in which the application roller is in rotational contact with the paper so that the moving direction of the roller outer peripheral surface and the paper transport direction are the same at the contact point between the roller and the paper (for example, Although the load applied to the paper by the roller can be small, the processing liquid intervening in the tapered gap (substantially triangular) between the paper and the roller on the exit side where the roller and the paper are separated from each other. There is a problem that the meniscus is likely to be disturbed, and chirimen-like unevenness (hereinafter referred to as chilimen unevenness) occurs on the coated surface of the paper.

  On the other hand, “reverse coating” is a method in which the coating roller is brought into rotational contact with the paper so that the moving direction of the roller outer circumferential surface and the paper transport direction are opposite at the contact point between the roller and the paper (for example, , Refer to Patent Document 2), the meniscus of the treatment liquid intervening in the tapered gap on the outlet side is relatively stable in comparison with the “forward application”, and it is easy to obtain a uniform application surface.

  Therefore, it is effective to use “reverse coating” in the sense of avoiding uneven chimney, but it is difficult to use “reverse coating” in an inkjet printer. This is because, in an ink jet printer, it is necessary to apply the treatment liquid to a sheet that is adsorbed and fixed on a rigid drum, but with the application roller in close contact with the sheet whose back is supported by a rigid body. This is because, if the rotation is reversed, a large frictional force is generated between the application roller and the paper, leading to damage such as paper tearing or wrinkling, and paper conveyance failure (jam).

  Originally, “reverse coating” is a method used for coating on a web-shaped recording medium. A coating roller is disposed between two support rollers separated in the transport direction, and the opposite side of the coating roller is constrained by a rigid body. Since the treatment liquid is applied to the recording medium in a state where it is not performed, the above-described problems such as damage to the recording medium do not occur.

JP 2006-110458 A

JP 2008-1000018 A

  In consideration of the above-described facts, an object of the present invention is to provide a processing liquid coating apparatus and an image forming apparatus that can alleviate the unevenness of the chirimen caused by forward coating and obtain a uniform coating surface of the processing liquid. .

  The processing liquid coating apparatus according to claim 1 is a storage unit configured to transport a sheet-like recording medium and a processing liquid that is applied to the recording medium before printing and performs preprocessing of the recording medium. A single metering roller that measures and supplies the processing liquid in the storage unit toward the recording medium transported by the transport unit, and a transport direction of the recording medium transported by the transport unit And a plurality of application rollers arranged along the conveyance direction of the recording medium in order to apply the processing liquid supplied from the metering roller side to the recording medium, Provided on the downstream side in the supply direction of the processing liquid, so that the application amount by the application roller on the downstream side in the recording medium conveyance direction is smaller than the application amount by the application roller on the upstream side in the conveyance direction of the recording medium. Plural Having an adjustment means for adjusting the processing liquid supply amount to the coating roller.

Next, the operation of the treatment liquid coating apparatus according to claim 1 will be described.
In the processing liquid coating apparatus according to the first aspect, the sheet-like recording medium is conveyed by the conveying means.
The measuring roller measures the treatment liquid in the storage unit and supplies the measured liquid toward the recording medium.
A plurality of application rollers arranged along the recording medium conveyance direction apply the treatment liquid to the recording medium.

  The adjusting means applies the treatment liquid to the plurality of application rollers so that the application amount of the treatment liquid by the application roller downstream in the recording medium conveyance direction is smaller than the application amount of the treatment liquid by the application roller upstream in the recording medium conveyance direction. Adjust the processing solution supply amount.

  Here, in the configuration of the processing liquid coating apparatus according to claim 1, the rotation direction of the coating roller is the forward direction (the conveyance of the recording medium conveyed by the conveying means) with respect to the conveying direction of the recording medium conveyed by the conveying means. Direction and the moving direction of the roller outer peripheral surface of the application roller at the portion in contact with the recording medium are set in the same direction), that is, the application method of the treatment liquid is so-called “forward rotation application”. A large frictional force does not act between the recording medium and the application roller, and it is possible to prevent the recording medium from being damaged or poorly conveyed.

  In the configuration of the first aspect of the present invention, since the plurality of application rollers are arranged along the conveyance direction of the recording medium, it is assumed that unevenness on the recording medium is caused on the recording medium when the processing liquid is applied by the upstream application roller. Even if it occurs, the downstream application roller repeatedly coats the processing liquid, so that the unevenness of the dust can be reduced. Furthermore, since the amount of application by the downstream application roller is less than the amount of application by the upstream application roller, the uneven chimney can be effectively reduced. Further, a leveling effect can be expected by the application roller on the downstream side.

  According to the first aspect of the present invention, an expensive metering roller is not provided for each of the plurality of application rollers, and only one metering roller is used, so that the cost of the processing liquid coating apparatus can be reduced. Moreover, since only one metering roller is used, the load of cleaning and maintenance of the metering roller can be reduced.

  According to a second aspect of the present invention, in the treatment liquid coating apparatus according to the first aspect, the adjusting unit is disposed on the upstream side in the transport direction of the recording medium and the downstream side in the transport direction of the recording medium. At least one intermediate roller in contact with the application roller, and the metering roller is in contact with the application roller disposed upstream in the conveyance direction of the recording medium.

Next, the operation of the treatment liquid coating apparatus according to claim 2 will be described.
In the processing liquid coating apparatus according to the second aspect, the processing liquid applied to the surface of the measuring roller is delivered to the coating roller disposed on the upstream side in the conveyance direction of the recording medium.

  The upstream application roller that has received the processing liquid from the metering roller applies the transferred processing liquid to the recording medium, but the processing liquid adhering to the outer peripheral surface is not transferred to the recording medium in its entirety. A part remains on the outer peripheral surface.

  The processing liquid remaining on the outer peripheral surface of the upstream application roller is transferred to the downstream application roller via the intermediate roller, and the downstream application roller receives the processing liquid received via the intermediate roller as a recording medium. Apply to.

  According to a third aspect of the present invention, in the processing liquid coating apparatus according to the first aspect, the adjusting means is provided corresponding to each of the plurality of coating rollers, and contacts the coating roller and the metering roller. At least one intermediate roller.

Next, the operation of the treatment liquid coating apparatus according to claim 3 will be described.
In the treatment liquid application apparatus according to the third aspect, the treatment liquid applied to the surface of the measuring roller is transmitted to each application roller via an intermediate roller provided corresponding to each application roller. In the processing liquid coating apparatus according to the third aspect, the same number of intermediate rollers as the coating rollers are provided.

  In the processing liquid coating apparatus according to the third aspect, the processing liquid applied to the surface of the measuring roller is delivered to the coating roller disposed on the upstream side through the intermediate roller disposed on the upstream side.

  The metering roller delivers the transferred processing liquid to the upstream intermediate roller, but the processing liquid adhering to the outer peripheral surface is not completely transferred to the upstream intermediate roller, and a part of the processing liquid remains on the outer peripheral surface.

  The processing liquid remaining on the outer peripheral surface of the measuring roller is transferred to the downstream application roller via the downstream intermediate roller, and the downstream application roller receives the processing liquid received via the downstream intermediate roller. Is applied to the recording medium.

  According to a fourth aspect of the present invention, in the treatment liquid coating apparatus according to any one of the first to third aspects, the surface energy of the coating roller is set smaller than the surface energy of the recording medium, The surface energy of the coating roller disposed on the downstream side of the recording medium in the conveyance direction is set larger than the surface energy of the coating roller disposed on the upstream side of the recording medium in the conveyance direction.

Next, the operation of the treatment liquid coating apparatus according to claim 4 will be described.
Since the surface energy of the coating roller is smaller than the surface energy (= hydrophilicity) of the recording medium, the treatment liquid of the coating roller can be efficiently transferred to the recording medium.

  In addition, since the surface energy of the downstream application roller is greater than that of the upstream application roller, the processing liquid adhered to the recording medium moves in the reverse direction from the downstream application roller to the upstream application roller. This can be prevented. Thereby, the relationship that the application amount of the upstream application roller is large and the application amount of the downstream application roller is small can be maintained.

  According to a fifth aspect of the present invention, in the treatment liquid coating apparatus according to the fourth aspect, the surface energy of the adjusting means is smaller than the surface energy of the coating roller disposed downstream in the conveyance direction of the recording medium. The surface energy of the coating roller disposed upstream in the conveyance direction of the recording medium is set larger.

Next, the operation of the treatment liquid coating apparatus according to claim 5 will be described.
The surface energy of the adjusting means is set to be smaller than the surface energy of the application roller arranged on the downstream side in the recording medium conveyance direction and larger than the surface energy of the application roller arranged on the upstream side in the conveyance direction of the recording medium. Therefore, it is possible to prevent the processing liquid adhering to the downstream application roller from moving in the reverse direction to the upstream application roller via the intermediate roller.

  According to a sixth aspect of the present invention, in the treatment liquid coating apparatus according to any one of the first to fifth aspects, the recording transported by the coating roller and the transporting unit on the downstream side in the recording medium transporting direction. L is a distance along the conveyance path of the recording medium from a contact portion with the medium to a contact portion between the coating roller on the upstream side in the recording medium conveyance direction and the recording medium conveyed by the conveyance means, and the recording medium L> V × T, where V is the transport speed of the recording medium, and T is the time during which the entire amount of the processing liquid applied to the recording medium by the application roller downstream in the recording medium transport direction penetrates the recording medium. Satisfied.

Next, the operation of the treatment liquid coating apparatus according to the sixth aspect will be described.
By satisfying L> V × T, the entire amount of the processing liquid applied on the upstream side penetrates into the recording medium before reaching the downstream application roller, and the processing liquid is applied to the inlet side of the downstream application roller. Can be prevented from accumulating, and appropriate multiple coating can be performed. If the processing liquid accumulates on the inlet side of the coating roller, the accumulated processing liquid flows outward in the axial direction of the coating roller, causing a problem that the processing liquid drops from the end of the coating roller.

  A seventh aspect of the present invention is the treatment liquid coating apparatus according to any one of the first to sixth aspects, wherein the outer diameter of the coating roller on the downstream side in the recording medium conveyance direction is upstream in the recording medium conveyance direction. It is set larger than the outer diameter of the application roller on the side.

Next, the operation of the treatment liquid coating apparatus according to the seventh aspect will be described.
It has been found by various experiments by the inventors that the coating surface shape in the forward rotation coating is greatly influenced by the amount of the processing liquid interposed in the tapered gap on the contact point exit side between the coating roller and the recording medium.

  When the amount of processing liquid intervening in the tapered gap on the contact point exit side between the coating roller and the recording medium is small, the accumulated processing liquid is likely to be disturbed by disturbance (vibration or liquid movement associated with rotation, etc.). The surface shape tends to be unstable, that is, unevenness tends to occur. Therefore, in order to stabilize the coating surface state, it is important to increase the amount of the processing liquid accumulated on the outlet side of the coating roller and to make the accumulated processing liquid less susceptible to disturbance.

  However, in the present invention, since the downstream application roller has a smaller application amount than the upstream application roller, the liquid film formed on the surface of the downstream application roller becomes thin. As a result, the downstream application roller has a smaller amount of processing liquid accumulated on the outlet side than the upstream application roller.

  Therefore, by setting the outer diameter of the downstream application roller to be larger than the outer diameter of the upstream application roller, the downstream application roller can prevent the processing liquid accumulated on the outlet side of the roller contact point even in forward rotation application. The amount can be increased, and the treatment liquid collected on the outlet side of the roller contact point can be stabilized, and thereby the coated surface can be further stabilized.

  An image forming apparatus according to claim 8 is a liquid for forming an image by ejecting liquid droplets onto the recording medium after applying the treatment liquid and the treatment liquid coating apparatus according to any one of claims 1 to 7. A droplet discharge device.

Next, the operation of the image forming apparatus according to the eighth aspect will be described.
In the image forming apparatus according to the eighth aspect, the processing liquid coating apparatus performs preprocessing by applying the processing liquid to the recording medium. Then, droplets are ejected from the droplet ejection device and attached to the pre-processed recording medium.

  Since the processing liquid is uniformly applied to the recording medium by the processing liquid coating apparatus according to any one of claims 1 to 7, the surface property of the recording medium is uniform and the droplets attached to the recording medium Unevenness in the shape does not occur, and high print quality can be obtained.

  According to the present invention, it is possible to alleviate the unevenness of the chirimen caused by forward application and uniformly apply the treatment liquid to the recording medium, so that high print quality can be obtained.

[First Embodiment]
The image forming apparatus 10 according to the first embodiment of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, in the image forming apparatus 10 according to the present embodiment, a sheet P is fed and conveyed upstream in the conveyance direction of a sheet as a recording medium (hereinafter referred to as “sheet P”). A paper transport unit 12 is provided. On the downstream side of the paper feeding / conveying unit 12, a processing liquid application unit 14 that applies a processing liquid to the recording surface of the paper P along the conveyance direction of the paper P, and an image formation that forms an image on the recording surface of the paper P A unit 16, an ink drying unit 18 that dries the image formed on the recording surface, an image fixing unit 20 that fixes the dried image on the paper P, and a discharge unit 21 that discharges the paper P on which the image is fixed are provided.

Hereinafter, each processing unit will be described.
(Paper feed section)
The paper feeding / conveying unit 12 is provided with a stacking unit 22 on which sheets P are stacked, and is downstream of the stacking unit 22 in the sheet conveying direction (hereinafter, “the conveying direction of the sheet P” may be omitted). The paper feeding unit 24 feeds the paper P stacked on the stacking unit 22 one by one.The paper P fed by the paper feeding unit 24 is composed of a plurality of pairs of rollers 26. It is conveyed to the treatment liquid application unit 14 through the configured conveyance unit 28.

(Processing liquid application part)
In the treatment liquid application unit 14, a treatment liquid application drum 30 is rotatably disposed. The treatment liquid coating drum 30 is provided with a holding member 32 that holds the paper P by sandwiching the leading end of the paper P, and the paper P is placed on the surface of the treatment liquid coating drum 30 via the holding member 32. In the state where the sheet P is held, the sheet P is conveyed to the downstream side by the rotation (in the direction of the arrow) of the treatment liquid coating drum 30.

  Note that an intermediate conveying drum 34, an image forming drum 36, an ink drying drum 38, and an image fixing drum 40, which will be described later, are also provided with a holding member 32 in the same manner as the processing liquid coating drum 30. The holding member 32 delivers the paper P from the upstream drum to the downstream drum.

  A processing liquid coating device 42 and a processing liquid drying device 44 are disposed on the upper portion of the processing liquid coating drum 30 along the circumferential direction of the processing liquid coating drum 30. A treatment liquid is applied to the recording surface, and the treatment liquid drying device 44 dries the treatment liquid.

(Processing liquid application equipment)
As shown in FIG. 2, the processing liquid coating apparatus 42 includes a storage unit 46 for storing the processing liquid 48, a metering roller 120, a first coating roller 122, a second coating roller 124, and an intermediate roller 126. ing.

  The measuring roller 120 is rotatably disposed above the storage unit 46, and a part of the lower side is immersed in the processing liquid 48 of the storage unit 46. The metering roller 120 is a motor (not shown) and rotates at a constant speed in the direction of the arrow (the direction opposite to the clockwise direction in FIG. 2).

  The treatment liquid 48 has an effect of aggregating the color material (pigment) and latex particles dispersed in the ink, which will be described later, into the treatment liquid, and has a function of forming an aggregate that does not generate a color material flow on the paper P. is doing. As an example of the reaction between the ink and the treatment liquid 48, a mechanism is used in which an acid is contained in the treatment liquid and the pigment dispersion is destroyed and aggregated by the PH down, and color material bleeding, color mixing between inks of each color, and ink droplet landing In this way, the droplet ejection interference due to the liquid coalescence is avoided.

  The first application roller 122 is disposed downstream of the measuring roller 120 in the rotation direction of the processing liquid application drum so as to come into contact with the measurement roller 120 and the processing liquid application drum 30. Accordingly, the first application roller 122 rotates in the opposite direction (clockwise direction in FIG. 2) with respect to the metering roller 120 and the treatment liquid application drum 30.

  A second application roller 124 is disposed on the downstream side of the first application roller 122 in the rotation direction of the processing liquid application drum so as to be separated from the first application roller 122. The first application roller 122 and the second application roller Above the intermediate portion of 124, an intermediate roller 126 is rotatably disposed so as to come into contact with the first application roller 122 and the second application roller 124.

  The second application roller 124 rotates in the opposite direction to the intermediate roller 126 and, like the first application roller 122, contacts the treatment liquid application drum 30 and is in the opposite direction to the treatment liquid application drum 30 ( In FIG. 2, it rotates clockwise.

  The metering roller 120 is in contact with a doctor blade 128 for removing excess processing liquid 48 adhering to the outer peripheral surface and making the thickness of the processing liquid 48 adhering to the outer peripheral surface constant. By rotating 120 (in the direction opposite to the clockwise direction in FIG. 2), a film-like processing liquid 48 having a certain thickness is obtained on the outer peripheral surface of the roller at the downstream side of the doctor blade 128 in the rotation direction of the measuring roller ( That is, the processing liquid is measured.)

  The measuring roller 120 may be of a general configuration, for example, an anilox roller having fine irregularities formed on the surface, or a wire roller (spiral roller) in which a thin wire is wound spirally on the outer peripheral surface. Etc. can be used.

In the treatment liquid coating apparatus 42, it is preferable to set the surface energy of each roller so that the surface energy (= hydrophilicity) of each roller is in the following order.
Paper P> second application roller 124> intermediate roller 126> first application roller 122.

  The surface energy may be adjusted by a conventionally known method such as a general method, for example, changing the surface roughness or shape, changing the material, or applying a hydrophilic coating.

  Also, as shown in FIG. 3, from the contact portion CP1 (downstream end) between the first application roller 122 and the paper P, the contact portion CP2 (upstream side) between the second application roller 124 and the paper P. L is the distance along the paper transport path to the edge), T is the time during which the entire amount of the processing liquid applied to the paper P by the first application roller 122 on the upstream side penetrates the paper P, and transports the paper P. When the speed is V, it is preferable that L> V × T. That is, before the sheet P comes into contact with the second application roller 124 on the downstream side, L, V, and so that the entire amount of the processing liquid applied to the sheet P by the first application roller 122 penetrates the sheet P. It is preferable to determine the relationship of T.

  Further, it is preferable to set the outer diameter D2 of the second application roller 124 on the downstream side in the rotation direction of the treatment liquid application drum 30 to be larger than the outer diameter D1 of the first application roller 122 on the upstream side.

  As shown in FIG. 1, the treatment liquid drying device 44 is provided with a hot air nozzle 54 and an infrared heater 56 (hereinafter referred to as “IR heater 56”) in proximity to the surface of the treatment liquid application drum 30. A solvent such as water in the processing liquid is evaporated by the hot air nozzle 54 and the IR heater 56 to form a solid or thin film processing liquid layer on the recording surface side of the paper P. By thinning the treatment liquid in the treatment liquid drying step, the dots deposited by ink in the image forming unit 16 come into contact with the surface of the paper to obtain the required dot diameter, and react with the thinned treatment liquid. It is easy to obtain an action of agglomerating color materials and fixing to the paper surface.

  In this way, the sheet P on which the processing liquid has been applied to the recording surface and dried by the processing liquid application unit 14 is conveyed to an intermediate conveyance unit 58 provided between the processing liquid application unit 14 and the image forming unit 16. .

(Intermediate transport section)
The intermediate conveyance unit 58 is rotatably provided with an intermediate conveyance drum 34. The sheet P is held on the surface of the intermediate conveyance drum 34 via a holding member 32 provided on the intermediate conveyance drum 34, and the intermediate conveyance drum 58 is intermediately conveyed. The sheet P is conveyed downstream by the rotation of the drum 34.

(Image forming part)
An image forming drum 36 is rotatably provided in the image forming unit 16, and the sheet P is held on the surface of the image forming drum 36 via a holding member 32 provided on the image forming drum 36 to form an image. The sheet P is conveyed downstream by the rotation of the drum 36.

  A head unit 66 composed of a single-pass ink-jet line head (droplet discharge device) 64 is disposed near the surface of the image forming drum 36 (described later). ). In this head unit 66, at least the basic colors YMCK inkjet line heads 64Y, 64M, 64C, and 64K are arranged along the circumferential direction of the image forming drum 36, and are formed on the recording surface of the paper P by the processing liquid application unit 14. An image of each color is formed on the processed treatment liquid layer.

  The treatment liquid has an effect of aggregating the color material (pigment) and latex particles dispersed in the ink into the treatment liquid, and forms an aggregate on the paper P that does not generate a color material flow. As an example of the reaction between the ink and the treatment liquid, acid is contained in the treatment liquid, pigment dispersion is destroyed by PH down, and the color material bleeds using a mechanism of aggregation, color mixing between each color ink, liquid mixture at the time of ink droplet landing Avoids droplet-interference caused by

  The ink jet line head 64 performs droplet ejection in synchronization with an encoder (not shown) that detects the rotational speed disposed on the image forming drum 36, thereby determining the landing position with high accuracy and at the same time. Irregular droplet ejection can be reduced without depending on the shake, the accuracy of the rotary shaft 68, and the drum surface speed.

  The head unit 66 can be retracted from the upper part of the image forming drum 36, and maintenance operations such as cleaning the nozzle surface of the inkjet line head 64 and discharging the thickened ink, the head unit 66 is moved to the upper part of the image forming drum 36. It is carried out by evacuating from.

  The sheet P on which the image is formed on the recording surface is transported to an intermediate transport unit 70 provided between the image forming unit 16 and the ink drying unit 18 by the rotation of the image forming drum 36. Since the configuration is substantially the same as that of the intermediate conveyance unit 58, description thereof is omitted.

(Ink drying section)
An ink drying drum 38 is rotatably provided in the ink drying unit 18, and a plurality of hot air nozzles 72 and IR heaters 74 are arranged above the ink drying drum 38 in the vicinity of the surface of the ink drying unit 18. It is installed.

  Here, as an example, the pair of IR heaters 74 arranged in parallel with the hot air nozzles 72 are alternately arranged so that the hot air nozzles 72 are arranged on the upstream side and the downstream side. In addition to this, a large number of IR heaters 74 are arranged on the upstream side to irradiate a large amount of thermal energy on the upstream side to increase the temperature of moisture, and a large number of hot air nozzles 72 are arranged on the downstream side to blow off saturated water vapor. Also good.

  Here, the hot air nozzle 72 is arranged so that the blowing angle of the hot air is inclined toward the rear end side of the paper P. Accordingly, the flow of hot air from the hot air nozzle 72 can be collected in one direction, and the paper P is pressed against the ink drying drum 38 side, and the state where the paper P is held on the surface of the ink drying drum 38 is maintained. be able to.

  The hot air generated by the hot air nozzle 72 and the IR heater 74 dries the solvent separated by the color material aggregating action in the image forming portion of the paper P, thereby forming a thin image layer.

  The hot air varies depending on the conveyance speed of the paper P, but is usually set to 50 ° C. to 70 ° C. The evaporated solvent is discharged together with air to the outside of the image forming apparatus 10, but the air is recovered. This air may be cooled by a cooler / radiator or the like and recovered as a liquid.

  The paper P on which the image on the recording surface has been dried is conveyed to an intermediate conveyance unit 76 provided between the ink drying unit 18 and the image fixing unit 20 by the rotation of the ink drying drum 38. Since the configuration is substantially the same as that of the intermediate conveyance unit 58, description thereof is omitted.

(Image fixing part)
An image fixing drum 40 is rotatably provided in the image fixing unit 20. In the image fixing unit 20, latex particles in a thin image layer formed on the ink drying drum 38 are heated / pressurized. And has a function of fixing and fixing on the paper P.

  A heating roller 78 is disposed above the image fixing drum 40 in the vicinity of the surface of the image fixing drum 40. The heating roller 78 has a halogen lamp incorporated in a metal pipe made of aluminum or the like having a good thermal conductivity. The heating roller 78 applies heat energy equal to or higher than the Tg temperature of the latex. As a result, the latex particles are melted and pressed into the unevenness on the paper P for fixing, and the unevenness on the surface of the image is leveled to obtain glossiness.

  A fixing roller 80 is provided on the downstream side of the heating roller 78. The fixing roller 80 is disposed in pressure contact with the surface of the image fixing drum 40 so as to obtain a nip force with the image fixing drum 40. I have to. Therefore, at least one of the fixing roller 80 and the image fixing drum 40 has an elastic layer on the surface and a uniform nip width with respect to the paper P.

  The sheet P on which the image on the recording surface is fixed by the above-described steps is conveyed to the discharge unit 21 provided on the downstream side of the image fixing unit 20 by the rotation of the image fixing drum 40.

  In this embodiment, the image fixing unit 20 has been described. However, the image fixing unit 20 is not necessarily required because it is sufficient that the image formed on the recording surface can be dried and fixed by the ink drying unit 18.

(Head unit)
As shown in FIG. 1, the head unit 66 is an ink jet as a plurality of liquid droplet ejection devices provided corresponding to yellow (Y), magenta (M), cyan (C), and black (K) inks. Line heads 64 </ b> Y, 64 </ b> M, 64 </ b> C, and 64 </ b> K are provided, and are arranged in order from the upstream side along the conveyance direction of the paper P.

  Each inkjet line head 64K, 64C, 64M, 64Y has an ink tank 67 in which the corresponding color ink is stored, and each ink tank 67 is connected to each inkjet line head 64K, 64C via a required pipe line. , 64M, 64Y communicates with a supply tank (not shown). When the remaining amount of ink in each supply tank decreases, ink is supplied from the corresponding ink tank 67.

  Each of the inkjet line heads 64Y, 64M, 64C, and 64K has a length corresponding to the maximum sheet width of the sheet P conveyed by the image forming drum 36, and the maximum size sheet P is drawn on the nozzle surface. This is a full-line head in which a plurality of ink ejection nozzles (not shown) are arranged over the entire possible range.

  In the present embodiment, a method of ejecting ink droplets by deformation of an actuator typified by a piezo element (piezoelectric element) is adopted, but in the practice of the present invention, the method of ejecting ink is not particularly limited, Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

  As described above, according to the configuration in which the full line type inkjet line heads 64Y, 64M, 64C, and 64K having nozzle rows covering the entire width of the paper are provided for each color, the conveyance direction of the paper P (arrow A direction; sub-scanning direction) ), The image can be recorded on the entire surface of the sheet P only by performing the operation of relatively moving the sheet P and the printing unit once (that is, by one sub-scan). Thereby, high-speed printing is possible and productivity can be improved as compared with a shuttle type head in which the head reciprocates in a direction (arrow B direction; main scanning direction) orthogonal to the paper transport direction.

  In this example, the configuration of the standard colors (4 colors) of YMCK is exemplified, but the combination of ink colors and the number of colors is not limited to this embodiment, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add an inkjet line head that discharges light-colored ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

(Function)
Next, the operation of the image forming apparatus 10 of this embodiment will be described.
First, in the paper feeding / conveying unit 12, the sheets P stacked on the stacking unit 22 are fed one by one by the paper feeding unit 24. The paper P fed by the paper feeding unit 24 is transported to the processing liquid coating unit 14 via a transport unit 28 constituted by a plurality of roller pairs 26.

  In the treatment liquid application unit 14, the measuring roller 120 rotates to measure the treatment liquid 48, and the measured treatment liquid 48 is delivered to the first application roller 122. As a result, the processing liquid 48 uniformly adheres to the outer peripheral surface of the first coating roller 122, and the processing liquid 48 is sequentially applied (transferred) to the paper P that is held and transported by the outer peripheral surface of the processing liquid coating drum 30. )

  Here, the processing liquid 48 remaining on the outer peripheral surface of the first application roller 122 after the sheet contact is transferred to the second application roller 124 via the intermediate roller 126. Compared with the amount of the processing liquid 48 applied to the paper P, the amount of the processing liquid 48 remaining on the outer peripheral surface after the paper contact (the amount of the processing liquid 48 delivered to the second application roller 124) is relatively Few.

  The paper P on which the processing liquid 48 is applied by the first application roller 122 is conveyed to the second application roller 124 side by the rotation of the processing liquid application drum 30, and the processing liquid 48 is overlapped by the second application roller 124. Painted.

For this reason, in the application of the treatment liquid 48 by the first application roller 122, even if the chimney unevenness occurs on the paper P, the second application roller 124 on the downstream side is smaller in amount than the first application roller 122. Since the treatment liquid 48 is overcoated, even if uneven chimney occurs, the chimney unevenness can be effectively reduced and a leveling effect can be expected.
Further, the first application roller 122 and the second application roller 124 rotate in the forward direction with respect to the transport direction of the paper P, that is, the application method of the processing liquid 48 is a so-called “forward application”. Therefore, a large frictional force does not act between the paper P and the first application roller 122, and between the paper P and the second application roller 124, and it is possible to prevent the paper P from being damaged or poorly conveyed. .

  In the image forming apparatus 10 of the present embodiment, the first application roller 122 and the second application roller 124 are not provided with the expensive measurement roller 120, and only one measurement roller 120 is required. Device cost can be reduced. Moreover, since only one measuring roller 120 is used, the load of cleaning and maintenance of the measuring roller 120 can be reduced.

  By setting “surface energy of the sheet P> surface energy of the second application roller 124> surface energy of the intermediate roller 126> surface energy of the first application roller 122”, the first application roller 122 and the second application energy The treatment liquid 48 of the application roller 124 can be efficiently transferred to the paper P, and the treatment liquid 48 moves in the reverse direction from the second application roller 124 on the downstream side to the first application roller 122 on the upstream side. The processing liquid 48 can be prevented from moving in the reverse direction toward the intermediate roller.

  Further, by setting L> V × T, the entire amount of the processing liquid 48 applied to the paper P by the first application roller 122 before the paper P comes into contact with the second application roller 124 on the downstream side is the paper. P can be penetrated. As a result, unnecessary processing liquid 48 is not accumulated on the inlet side of the second application roller 124.

  Furthermore, by setting the outer diameter of the second application roller 124 on the downstream side to be larger than the outer diameter of the first application roller 122 on the upstream side, the roller contact of the second application roller 124 on the downstream side is established. The amount of the processing liquid 48 that accumulates on the point exit side can be increased and stabilized, and as a result, the coated surface shape can be further stabilized. 4A shows the case where the outer diameter of the second application roller 124 is small, and FIG. 4B shows the case where the outer diameter of the second application roller 124 is large. It can be seen that the larger the outer diameter of the application roller 124, the larger the amount of the processing liquid 48 accumulated on the outlet side of the roller contact point.

  Thus, the processing liquid drying device 44 dries the processing liquid on the paper P coated with the processing liquid 48. The paper P on which the processing liquid 48 has been applied and dried on the recording surface by the processing liquid application unit 14 is conveyed to the image forming unit 16 via the intermediate conveyance unit 58.

  In the image forming unit 16, an image of each color is formed by the inkjet line head 64 on the processing liquid layer formed on the recording surface of the paper P by the processing liquid application unit 14.

  The paper P on which the image is formed on the recording surface is conveyed to the ink drying unit 18 via the intermediate conveyance unit 70. In the ink drying unit 18, the paper P is heated, and the solvent separated by the color material aggregation action is dried to form a thin image layer. The paper P on which the ink on the recording surface has been dried is conveyed to the image fixing unit 20 via the intermediate conveyance unit 76.

  In the image fixing unit 20, latex particles in the thin image layer formed on the ink drying drum 38 are heated / pressurized and melted, and fixed and fixed on the paper. The heating roller 78 applies thermal energy equal to or higher than the Tg temperature of the latex, whereby the latex particles are melted and pressed into the irregularities on the paper for fixing and leveling the irregularities on the image surface to obtain gloss. .

  The sheet P on which the image on the recording surface is fixed by the above-described steps is conveyed to the discharge unit 21 provided on the downstream side of the image fixing unit 20 by the rotation of the image fixing drum 40.

  In the image forming apparatus 10 of the present embodiment, there are two application rollers. However, the present invention is not limited to this, and three or more application rollers may be provided. Even in this case, an intermediate roller that contacts both the upstream application roller and the downstream application roller adjacent thereto is arranged.

[Second Embodiment]
Next, an image forming apparatus 10 according to a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
As shown in FIG. 5, in the treatment liquid coating device 42 of the image forming apparatus 10 of the present embodiment, a first intermediate roller 130 is disposed between the metering roller 120 and the first coating roller 122, and the metering roller 120. The second intermediate roller 132 is disposed between the first application roller 124 and the second application roller 124.

  In the processing liquid coating apparatus 42 of this embodiment, the measuring roller 120 rotates to measure the processing liquid 48, and the measured processing liquid 48 is received by the first coating roller 122 via the first intermediate roller 130. Passed. Here, the processing liquid 48 remaining on the outer peripheral surface of the measuring roller 120 is then transferred to the second application roller 124 via the second intermediate roller 132. Note that the amount of processing liquid 48 remaining on the outer peripheral surface after contact with the first intermediate roller (delivered to the second intermediate roller 132 as compared with the amount of processing liquid 48 applied to the first intermediate roller 130. The amount of treatment liquid 48) is relatively small.

  As in the first embodiment, the sheet P coated with the treatment liquid 48 by the first application roller 122 is conveyed to the second application roller 124 side by the rotation of the treatment liquid application drum 30, and the second application roller 124 is rotated. Since the processing liquid 48 is overcoated by the application roller 124, first, as in the embodiment, the uneven chimney can be effectively reduced, and a leveling effect can also be expected.

  In the present embodiment, the first application roller 122 and the second application roller 124 are set to have the same outer diameter, but the outer diameter of the second application roller 124 is the same as in the first embodiment. May be larger than the outer diameter of the first application roller 122.

  The relationship between the surface energies of the rollers is as follows: first application roller 122> first intermediate roller 130> metering roller 120, second application roller 124> second intermediate roller 132> metering roller 120, second. Application roller 124> first application roller 122 is preferable.

  In this embodiment, there are two application rollers. However, the present invention is not limited to this, and three or more application rollers may be provided. In this case, an intermediate roller that contacts the measuring roller 120 and each application roller is disposed.

[Other Embodiments]
In the processing liquid coating apparatus of the above embodiment, the example in which the processing liquid for performing the preprocessing before the ink is applied is applied to the paper, but the present invention is not limited to this, and the recording medium to which the processing liquid is applied Is not limited to paper, and may be another type of recording medium such as a printed circuit board or a printing plate.

  In the above-described embodiment, the example in which the processing liquid coating apparatus is applied to the image forming apparatus has been described. However, the target to which the processing liquid coating apparatus is applied is not limited to the image forming apparatus.

1 is an overall configuration diagram illustrating a configuration of an image forming apparatus according to a first embodiment. It is a side view of a processing liquid application device. It is the side view to which the application roller vicinity was expanded. (A) is a side view of the downstream application roller when the outer diameter is small, and (B) is a side view of the downstream application roller when the outer diameter is large. It is a side view of the processing liquid coating device of the image forming apparatus according to the second embodiment.

Explanation of symbols

10 Image forming apparatus P Paper (recording medium)
30 Treatment liquid application drum (conveyance means)
42 treatment liquid coating apparatus 46 storage section 64 inkjet line head (droplet ejection apparatus)
120 Metering roller 122 First application roller 124 Second application roller 126 Intermediate roller (adjusting means)
130 First intermediate roller (adjusting means)
132 Second intermediate roller (adjusting means)

Claims (8)

Conveying means for conveying a sheet-like recording medium;
A storage unit that stores a processing liquid that is applied to the recording medium before printing and performs preprocessing of the recording medium;
A single metering roller for metering and supplying the processing liquid in the reservoir toward the recording medium transported by the transport means;
A plurality of recording mediums rotated in the forward direction and in the forward direction of the recording medium transported by the transporting means, and applied along the transporting direction of the recording medium in order to apply the processing liquid supplied from the metering roller side to the recording medium. Disposed application roller;
An application amount by the application roller provided downstream of the measuring roller in the supply direction of the processing liquid and applied downstream of the recording medium in the conveyance direction rather than an application amount by the application roller in the upstream of the recording medium in the conveyance direction Adjusting means for adjusting the supply amount of the processing liquid to the plurality of application rollers,
A treatment liquid coating apparatus. The adjusting means includes at least one intermediate roller that contacts the application roller disposed on the upstream side in the conveyance direction of the recording medium and the application roller disposed on the downstream side in the conveyance direction of the recording medium,
The processing liquid coating apparatus according to claim 1, wherein the measuring roller is in contact with the coating roller disposed upstream in the conveyance direction of the recording medium.   2. The processing liquid coating apparatus according to claim 1, wherein the adjustment unit includes at least one intermediate roller that is provided corresponding to each of the plurality of coating rollers and is in contact with the coating roller and the metering roller. . The surface energy of the application roller is set smaller than the surface energy of the recording medium,
The surface energy of the coating roller disposed on the downstream side in the conveyance direction of the recording medium is set larger than the surface energy of the coating roller disposed on the upstream side in the conveyance direction of the recording medium. 4. The treatment liquid coating apparatus according to any one of 3 above.   The surface energy of the adjusting means is smaller than the surface energy of the coating roller disposed on the downstream side in the conveyance direction of the recording medium, and is smaller than the surface energy of the coating roller disposed on the upstream side in the conveyance direction of the recording medium. The processing liquid coating apparatus according to claim 4, which is set to be large.   From the contact portion between the application roller downstream in the recording medium conveyance direction and the recording medium conveyed by the conveyance means, the application roller upstream in the recording medium conveyance direction and the recording medium conveyed by the conveyance means The distance along the conveyance path of the recording medium to the contact portion is L, the conveyance speed of the recording medium is V, and the total amount of the processing liquid applied to the recording medium by the application roller on the downstream side in the recording medium conveyance direction is 6. The treatment liquid coating apparatus according to claim 1, wherein L> V × T is satisfied, where T is a time permeating the recording medium.   The outer diameter of the application roller on the downstream side in the recording medium conveyance direction is set to be larger than the outer diameter of the application roller on the upstream side in the recording medium conveyance direction. Treatment liquid coating device. The treatment liquid coating apparatus according to any one of claims 1 to 7,
A droplet discharge device that discharges droplets onto the recording medium after application of the treatment liquid to form an image;
An image forming apparatus.

Images