JP7643168B2 - Heating device, drying device, liquid ejection device - Google Patents

Description

The present invention relates to a heating device, a drying device, and a device for ejecting liquid.

Among devices equipped with a means for ejecting liquid, there are some equipped with a drying device that includes a heating means for heating the sheet material (receiving member) to which the liquid has been applied.

Conventionally, there is known a device that includes a first heating means for heating a sheet material to which liquid has been applied, a suction conveying means for sucking and conveying the sheet material that has passed through the first heating means, and a second heating means for heating the sheet material being conveyed by the suction conveying means (Patent Document 1).

JP 2021-035761 A

However, even with a device like that disclosed in Patent Document 1, there is still a need to further improve the drying efficiency.

The present invention was made in consideration of the above problems, and aims to improve drying efficiency.

In order to solve the above problems, the heating device according to the present invention comprises:
A first heating means for heating the sheet material to which the liquid has been applied;
A second heating means disposed downstream of the first heating means in a sheet conveying direction;
a transport means for transporting the sheet material toward the second heating means ,
the first heating means is capable of changing a heating direction between a direction for heating the sheet material upstream of the transport means and a direction for heating the sheet material being transported by the transport means,
The device is configured to include a means for controlling the heating direction of the first heating means based on information about the sheet material , so as to heat the sheet material upstream of the transport means, or to heat the sheet material being transported by the transport means .

The present invention improves drying efficiency.

1 is a schematic explanatory diagram of a printing apparatus that is an apparatus for ejecting liquid according to a first embodiment of the present invention. FIG. 2 is a plan view illustrating an example of a discharge unit of the printing apparatus; FIG. 2 is a side view illustrating the heating device according to the first embodiment of the present invention. FIG. 13 is a perspective view illustrating a different example of a conveyor belt. FIG. 2 is a block diagram of a portion relating to heating control in the heating device according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram of an example of a table stored in a storage unit. 11 is a flow diagram illustrating control of the heating direction (attitude) of the first heating means by the heating control means; FIG. 11 is an explanatory diagram of a transition of ink temperature at a sheet material conveying position, for explaining an example of a relationship between a heating direction of a first heating means and a transition of temperature of liquid (ink) on a sheet material. FIG. FIG. 11 is a schematic explanatory diagram of a printing apparatus that is an apparatus for ejecting liquid according to a second embodiment of the present invention. FIG. 11 is a block diagram of a portion relating to heating control in a heating device according to a second embodiment of the present invention. FIG. 4 is an explanatory diagram of an example of a table stored in a storage unit. 11 is a flow diagram illustrating control of the heating direction (attitude) of the first heating means by the heating control means; FIG. FIG. 11 is an explanatory diagram illustrating a heating device according to a third embodiment of the present invention. FIG. 10 is a side view illustrating a heating device according to a fourth embodiment of the present invention. FIG. 13 is a side view illustrating a portion of a first heating means of a heating device according to a fifth embodiment of the present invention.

Embodiments of the present invention will now be described with reference to the accompanying drawings. First, a printing device, which is a device for ejecting liquid according to a first embodiment of the present invention, will be described with reference to Figs. 1 and 2. Fig. 1 is a schematic diagram of the printing device, and Fig. 2 is a plan view of an example of an ejection unit of the printing device.

The printing device 1 comprises an input section 10, a printing section 20, a drying section 30, and an unloading section 40. In the printing device 1, the printing section 20 applies liquid to the sheet material P that is input from the input section 10 to perform the required printing, and the drying section 30 dries the liquid adhering to the sheet material P, after which the sheet material P is discharged to the unloading section 40.

The operation unit 80 inputs printing conditions and the like to the printing device 1. The control unit 91 of the control device 90 controls printing operations and the like based on the input from the operation unit 80 and a table of operations for the settings stored in the memory unit 92.

The loading section 10 includes an input tray 11 on which multiple sheet materials P are loaded, and a feeding device 12 that separates and sends out the sheet materials P one by one from the input tray 11.

The feeding device 12 can be any type of feeding device, such as a device using rollers or a device using air suction. The sheet material P sent out from the input tray 11 by the feeding device 12 is sent to the printing unit 20.

The printing section 20 is equipped with a pair of registration rollers 21 that are driven at a predetermined timing to feed out the sheet material P after it arrives at the printing section 20 from the loading section 10.

The printing unit 20 also includes a sheet transport device 22 that transports the sheet material P. The sheet transport device 22 includes a drum 23, which is a support member (rotating member) that supports the sheet material P on its circumferential surface and rotates, and a suction device 24, which is a suction means that generates a suction force on the circumferential surface of the drum 23.

The printing unit 20 also includes a liquid ejection unit 25 that ejects and applies liquid to the sheet material P carried and transported by the drum 23 of the sheet transport device 22.

The printing section 20 also includes a transfer cylinder 26 that receives the fed sheet material P and transfers it between the drum 23, and a transfer cylinder 27 that transfers the sheet material P transported by the drum 23 to the drying section 30.

The sheet material P transported from the loading section 10 to the printing section 20 is sent to the transfer drum 26 at a predetermined timing by the pair of registration rollers 21, the leading edge is gripped by a gripping means (gripper) provided on the transfer drum 26, and is transported as the transfer drum 26 rotates. The sheet material P transported by the transfer drum 26 is handed over to the drum 23 at a position opposite the drum 23.

A gripping means (gripper) is provided on the surface of the drum 23, and the leading edge of the sheet material P is gripped by the gripper. A number of suction holes are formed and distributed on the surface of the drum 23. The suction device 24 generates a suction airflow that flows inward from the required suction holes of the drum 23.

Then, the sheet material P transferred from the transfer cylinder 26 to the drum 23 has its leading edge gripped by the gripper, is adsorbed and supported on the drum 23 by the suction airflow of the suction device 24, and is transported as the drum 23 rotates.

The liquid ejection section 25 is equipped with ejection units 28 (28A to 28F) which are liquid application means. For example, ejection unit 28A ejects black (K) liquid, ejection unit 28B ejects cyan (C) liquid, ejection unit 28C ejects magenta (M) liquid, and ejection unit 28D ejects yellow (Y) liquid.

The ejection units 28E and 28F are used to eject special liquids such as YMCK, white, gold (silver), etc. Furthermore, an ejection unit that ejects a treatment liquid such as a surface coating liquid can also be provided.

The ejection unit 28 is, for example, a full-line type head in which multiple liquid ejection heads (hereinafter simply referred to as "heads") 100, each having a nozzle row 101 in which multiple nozzles are arranged, are arranged on a base member 102, as shown in FIG. 2.

The ejection operation of each ejection unit 28 of the liquid ejection section 25 is controlled by a drive signal corresponding to the printing information.

When the sheet material P supported on the drum 23 passes through the area facing the liquid ejection section 25, liquid of each color is ejected from the ejection unit 28, and an image corresponding to the printing information is printed.

The sheet material P to which liquid has been applied by the liquid discharge unit 25 is sent from the surface of the drum 23 to the transfer drum 27, which is a transfer rotating body.

A gripping means (gripper) for gripping the leading edge of the sheet material P is also provided on the surface of the transfer cylinder 27, and the leading edge of the sheet material P is transferred from the gripper of the drum 23 to the gripper of the transfer cylinder 27, so that the sheet material P is transferred from the surface of the drum 23 to the transfer cylinder 27.

Then, the sheet material P is transferred to the suction transport mechanism 33 of the drying section 30 via the peripheral surface (transfer path) of the transfer cylinder 27 as the transfer cylinder 27 rotates.

Here, a first drying means 31 for drying the sheet material P is disposed between the printing unit 20 and the drying unit 30, and the liquid adhered to the sheet material P in the printing unit 20 can be heated and dried by the first drying means 31.

The drying section 30 includes a second drying means 32 that heats and dries the liquid on the sheet material P, and a suction conveying mechanism 33 that is a conveying means that conveys (suction conveys) the sheet material P delivered from the delivery cylinder 27 of the printing section 20 in a suctioned state.

The sheet material P to which liquid has been applied in the printing unit 20 is heated by the first drying means 31 when it is transferred to the suction transport mechanism 33 by the transfer drum 27, and is further heated by the second drying means 32 while being transported by the suction transport mechanism 33, and is sent to the discharge unit 40. Note that the inside of the transfer drum 27 may be hollow or mesh-like, so that the sheet material P to which liquid has been applied can be directly dried by the heating of the first drying means 31.

When passing through the second drying means 32, the liquid on the sheet material P that has been heated (pre-heated) by the first drying means 31 is further subjected to a heat treatment.

This causes the water and other liquid components in the liquid to evaporate, ensuring that the colorant contained in the liquid is fixed onto the sheet material P and also preventing the sheet material P from curling.

The discharge section 40 is equipped with a discharge tray 41 on which multiple sheet materials P are stacked. The sheet materials P conveyed from the drying section 30 are stacked and held on the discharge tray 41 in sequence.

Here, we will explain the ink used as the liquid in the printing device 1.

The ink in this embodiment is a water-based ink, containing an organic solvent, water, coloring material, resin, and additives.

<Ink>
The organic solvent, water, coloring material, resin, additives, etc. used in the ink will be described below.
<Organic Solvent>
The organic solvent is not particularly limited, and any water-soluble organic solvent can be used. Examples of the organic solvent include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

It is preferable to use an organic solvent with a boiling point of 250°C or less, as this not only functions as a wetting agent but also provides good drying properties.

The content of the organic solvent in the ink is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of the drying property and ejection reliability of the ink, it is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

<Water>
The water content in the ink is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of the drying property and ejection reliability of the ink, however, the water content is preferably from 10% by mass to 90% by mass, and more preferably from 20% by mass to 60% by mass.

<Coloring material>
The coloring material is not particularly limited, and a pigment is used.

As the pigment, an inorganic pigment or an organic pigment can be used. These can be used alone or in combination of two or more kinds. Also, mixed crystals can be used as the pigment.

The content of colorant in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoints of improving image density, good fixation property and ejection stability.

Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy pigments such as gold and silver pigments, and metallic pigments.

<Resin>
The type of resin contained in the ink is not particularly limited and can be appropriately selected depending on the purpose. Examples of the resin include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin.

The content of the resin is not particularly limited and can be appropriately selected depending on the purpose.
From the viewpoint of fixability and storage stability of the ink, the content of the toner is preferably from 1% by mass to 30% by mass, and more preferably from 5% by mass to 20% by mass, based on the total amount of the ink.

<Additives>
If necessary, surfactants, antifoaming agents, antiseptic and antifungal agents, rust inhibitors, pH adjusters, and the like may be added to the ink.

Next, the heating device according to the first embodiment of the present invention will be described with reference to Figures 3 and 4. Figure 3 is a side view of the heating device according to the first embodiment, and Figure 4 is a perspective view of a different example of the conveyor belt.

The heating device 300 also functions as a drying device, and includes a first heating means 301, a second heating means 302 arranged downstream of the first heating means 301 in the sheet material conveying direction, and a suction conveying mechanism 303 as a transfer means and conveying means.

The first heating means 301 is equipped with one or more hot air blowing means 311 including, for example, an infrared heater capable of radiating heat transfer and a blowing means. Note that the first heating means 301 is not limited to the hot air blowing means 311, and an infrared irradiation means such as an IR heater, a near-infrared irradiation means, or a combination of these may be used. The first heating means 301 becomes the first drying means 31.

The second heating means 302 includes, for example, one or more hot air blowing means 321 arranged along the conveying direction within the housing 320. The second heating means 302 serves as the second drying means 32. The second heating means 302 may be an infrared ray irradiation means such as an IR heater, a near-infrared ray irradiation means, an ultraviolet ray irradiation means, or a combination of these.

The suction conveying mechanism 303 is equipped with a conveying belt 331 that adsorbs and conveys the sheet material P delivered from the delivery cylinder 27. The conveying belt 331 is stretched between a driving roller 332 and a driven roller 333, and moves in a circle by driving the driving roller 332.

In this embodiment, the conveyor belt 331 of the suction conveying mechanism 303 is disposed across from the transfer cylinder 27 to the second heating means 302. As a result, the conveyor belt 331 serves both as a conveying means for conveying the sheet material P facing the second heating means 302, and as a transporting means for transferring the sheet material P to the conveying means in the portion upstream of the second heating means 302.

Here, the conveyor belt 331 has a ventilation structure with multiple through holes (suction holes) distributed on its surface. In addition, a suction chamber 334 is arranged inside the conveyor belt 331 as a suction mechanism, and the sheet material P is adsorbed to the conveyor belt 331 by suctioning the inside of the suction chamber 334.

The conveyor belt 331 may be, for example, a glass fiber mesh belt. The mesh belt has linear members arranged in a mesh pattern, as shown in FIG. 4(a). By using a mesh belt, it is possible to reduce flapping of the sheet material P caused by rebounding of the hot air blown by the hot air blowing means 321.

The conveyor belt 331 may have suction holes (suction openings) formed on its surface, and may be configured to support the sheet material P with a plurality of support wires 331a as shown in FIG. 4(b), or may be made of a porous material. The suction openings are not limited to a rectangular shape, and may be circular, for example.

The amount of heat applied to the sheet material P by the second heating means 302 is greater than the amount of heat applied to the sheet material P by the first heating means 301.

In this way, the sheet material P heated by the first heating means 301 is further heated by the second heating means 302, so that the liquid applied to the sheet material P can be reliably dried.

The first heating means 301 is arranged so that the heating direction (the direction in which radiant heat is blown from the first heating means 301) can be changed. In other words, the first heating means 301 can be changed between a position in which the heating direction is direction A as shown in FIG. 3(a) (the position shown by the solid line in FIG. 1) and a position in which the heating direction is direction B as shown in FIG. 3(b) (the position shown by the virtual line in FIG. 1).

When the first heating means 301 is oriented so that the heating direction is in the direction A, the sheet material P is heated upstream of the conveyor belt 331, which also serves as the transfer means. In other words, the sheet material P is heated before it is handed over from the transfer cylinder 27 to the part of the conveyor belt 331 that serves as the transfer means.

When the first heating means 301 is oriented so that the heating direction is in the direction B, the sheet material P is heated after it is transferred from the transfer cylinder 27 to the conveyor belt 331 and before it faces the second heating means 302. In other words, the sheet material P is heated before the entrance of the second heating means 302 and is being transferred on the part of the conveyor belt 331 that serves as the transfer means.

Next, the portion related to the heating control in the heating device according to the first embodiment of the present invention will be described with reference to Figs. 5 and 6. Fig. 5 is a block diagram of the portion related to the control, and Fig. 6 is an explanatory diagram of an example of a table stored in the storage means.

The operation means 801 can input information on the basis weight or thickness of the sheet material P. The information on the basis weight or thickness of the sheet material P is information about the sheet material P.

The operation means 801 can be configured, for example, by an operation panel (operation screen) of the operation unit 80 provided in the printing device 1, or a print instruction terminal (e.g., a computer) connected to the printing device 1.

As shown in FIG. 6, the storage means 902 stores a table that shows the relationship between the basis weight or thickness information of the sheet material P and the heating direction of the first heating means 301.

In this embodiment, when the basis weight of the sheet material P is equal to or less than a predetermined value, the basis weight is "small," and when the basis weight is greater than the predetermined value, the basis weight is "large." For example, when the basis weight of the sheet material P is equal to or less than 150 gsm, the basis weight is small, and when the basis weight is greater than 150 gsm, the basis weight is large. In addition, when the thickness of the sheet material P is used as the standard, for example, when the thickness is 0.17 mm or less, the sheet material is considered to be "thin paper," and when the thickness is greater than 0.17 mm, the sheet material is considered to be "thick paper."

When the basis weight is small (thin paper), the heating direction (position) of the first heating means 301 is set to direction A, which heats the sheet material before it is handed over to the conveyor belt 331, and when the basis weight is large (thick paper), the heating direction (position) of the first heating means 301 is set to direction B, which heats the sheet material just before the entrance of the second heating means 302 and being conveyed by the conveyor belt 331.

The heating control means 901 reads out a table from the storage means 902 based on the information on the basis weight or thickness of the sheet material P input from the operation means 801, and controls the driving of the heating direction driving unit 315 to control the heating direction (posture) of the first heating means 301. In other words, the heating control means 901 is a means for selectively heating the sheet material P upstream of the conveyor belt 331, which serves as the transport means, or the sheet material P being transported by the transport means, using the first heating means 301, based on the information on the sheet material P.

The heating control means 901 also controls the heating of the sheet material P by the first heating means 301 and the heating of the sheet material P by the second heating means 302.

Next, the heating direction (posture) control of the first heating means 301 by the heating control means 901 will be described with reference to the flow diagram in Figure 7.

The operator sets the basis weight or thickness of the sheet material P using the operation means 801 (step S1, hereafter simply referred to as "S1"). Note that in FIG. 7, this is expressed as the thickness of the sheet material P.

The heating control means 901 retrieves the information on the basis weight or thickness of the sheet material P set by the operation means 801, and reads the table stored in the memory unit 92 (S2).

Then, the heating control means 901 controls the heating direction drive unit 315 based on the loaded table to switch the heating direction of the first heating means 301.

In other words, the heating control means 901 determines whether the sheet material P is thin paper or thick paper (S3).

Here, when the sheet material P is thin paper, the heating control means 901 sets the heating direction of the first heating means 301 to direction A, i.e., the direction in which the sheet material P is heated before being handed over to the conveyor belt 331 (S4).

In contrast, when the sheet material P is thick paper, the heating control means 901 sets the heating direction of the first heating means 301 to direction B, i.e., the direction just before the entrance of the second heating means 302, in which the sheet material P being transported by the transport belt 331 is heated (S5).

Next, an example of the relationship between the heating direction of the first heating means and the change in the liquid temperature (here, the ink temperature) on the sheet material will be described with reference to FIG. 8. FIG. 8 is an explanatory diagram of the change in the ink temperature at the sheet material conveying position for use in the description.

First, when the heating direction of the first heating means 301 is direction A, the ink temperature changes as shown by the dashed line in Figure 8.

In other words, when the heating direction of the first heating means 301 is direction A, the sheet material P is heated when it passes through the transfer cylinder 27 on the upstream side of the conveyor belt 331. Therefore, the ink temperature rises when the sheet material P passes through the transfer cylinder 27, and after passing through the transfer cylinder 27 and being handed over to the conveyor belt 331, the ink temperature drops once before reaching the entrance of the second heating means 302. Thereafter, as the sheet material P is conveyed by the conveyor belt 331 opposite the second heating means 302, the ink temperature rises and reaches a peak temperature near the exit of the second heating means 302.

In this way, the sheet material P is heated by the first heating means 301 before it is placed on the conveyor belt 331, and then heated by the second heating means 302 after the ink temperature has temporarily dropped.

Here, since the conveyor belt 331 faces the hot air blowing means 321, the temperature of the belt surface (the surface that comes into contact with the sheet material P) rises, but since the air intake opening of the conveyor belt 331 is an open space, the temperature does not rise like the belt surface.

Therefore, when the sheet material P is placed on the belt surface of the conveyor belt 331 while the water-based liquid (ink) is not yet completely dry, the pigment in the ink on the sheet material P flows due to the temperature difference between the belt surface and the intake opening, and a pattern (color unevenness) corresponding to the shape of the mesh of the mesh belt, for example, appears in the image. Color unevenness occurs particularly when the sheet material P is thin or is coated paper (a sheet with a paint applied to the surface to increase smoothness) with a small basis weight.

Therefore, as in this embodiment, the ink flow can be suppressed by performing heating (pre-drying) by the first heating means 301 before heating (main drying) by the second heating means 302 on the conveyor belt 331. This makes it possible to prevent abnormal images in which traces of suction openings such as suction holes in the conveyor belt 331 (for example, mesh marks) appear on the image.

In other words, when a water-based liquid (ink) is applied to a sheet material and the sheet material P is dried while being adsorbed and transported by a transport belt such as a mesh belt having suction openings, the occurrence of abnormal images can be prevented by performing pre-drying before the sheet material P is placed on the transport belt.

Next, the change in ink temperature when the heating direction of the first heating means 301 is direction B is shown by the solid line in Figure 8.

In other words, when the heating direction of the first heating means 301 is set to direction B, the ink temperature rises as the sheet material P passes through the transfer cylinder 27, is handed over to the conveyor belt 331, and is conveyed to just before the entrance of the second heating means 302. Then, as the sheet material P with the increased ink temperature is conveyed by the conveyor belt 331 facing the second heating means 302, the ink temperature rises further and reaches a peak temperature near the exit of the second heating means 302.

In this way, because the ink temperature of the sheet material P is increased when it enters the second heating means 302, the peak temperature of the ink temperature near the exit of the second heating means 302 is higher than the peak temperature when the heating direction of the first heating means 301 is in direction A. As a result, when the heating direction of the first heating means 301 is in direction B, evaporation of moisture is more promoted than when it is in direction A.

Here, in relation to the heating direction of the first heating means 301 and the basis weight or thickness of the sheet material, when the sheet material P is thick paper, the temperature difference between the belt surface and the suction opening on the back surface of the sheet material P is equalized before being transmitted to the ink layer on the front surface of the sheet material P.

Therefore, since no ink flow occurs on the surface of the sheet material P, heating in direction A by the first heating means 301 is not necessary. Therefore, by heating in direction B by the first heating means 301, which can promote evaporation, it becomes possible to dry the cardboard in a space-saving manner without increasing the number of heaters. Note that when the sheet material P is thin paper, it does not require as much heat as cardboard, so it can be dried by heating only by the second heating means 302.

In this way, for thin paper (sheet material P on which color unevenness occurs due to uneven heating) in which temperature unevenness on the conveyor belt 331 is easily transmitted to the ink on the sheet material P, the first heating means 301 is set in the direction A to heat (pre-dry) the sheet material P.

For thin paper, by heating the sheet material P using the first heating means 301 before it is placed on the conveyor belt 331, it is possible to suppress uneven drying, uneven gloss, and uneven images caused by the movement of pigment on the surface of the sheet material P to which the printing liquid has been applied.

On the other hand, even if there are temperature unevenness in the conveyor belt 331, the temperature difference is mitigated while heat is transferred through the sheet material P, and for thick paper (sheet material P that does not suffer from color unevenness due to uneven heating) on which temperature differences are unlikely to be applied, heating is performed by setting the first heating means 301 in direction B.

By heating the sheet material P with the second heating means 302 immediately after heating with the first heating means 301, the peak temperature of the ink can be increased and drying can be accelerated. In this way, when the sheet material is thick paper (having a large basis weight), by utilizing the heating of the first heating means 301, the thick paper can be dried efficiently in a space-saving manner without increasing the number of heaters of the second heating means 302, improving the drying efficiency of the thick paper.

Next, the heating direction of the first heating means and the transport distance of the sheet material after heating by the first heating means until heating by the second heating means begins will be described with reference to FIG. 3 mentioned above.

As shown in FIG. 3(a), when heating is performed with the first heating means 301 in the A direction, the transport distance of the sheet material P after being heated by the first heating means 301 and before being heated by the second heating means 302 is, for example, the distance from the transfer position from the transfer cylinder 27 to the position where it is heated by the hot air blowing means 321 at the most upstream of the second heating means 302.

On the other hand, as shown in FIG. 3(b), when heating is performed with the first heating means 301 in the direction B, the transport distance of the sheet material P after being heated by the first heating means 301 until it is heated by the second heating means 302 is, for example, the distance from the position where it is heated by the most downstream hot air blowing means 311 of the first heating means 301 to the position where it is heated by the most upstream hot air blowing means 321 of the second heating means 302.

In other words, when heating of the sheet material P by the first heating means 301 is started upstream of the transport means, the transport distance over which the sheet material P is heated by the first heating means 301 and then by the second heating means 302 is longer than when heating is started after the transport means has started to transport the sheet material.

Next, a printing device that ejects liquid according to a second embodiment of the present invention will be described with reference to FIG. 9. FIG. 9 is a schematic diagram of the printing device.

In the printing device 1 of this embodiment, in addition to the configuration of the printing device 1 of the first embodiment, a pre-treatment unit 50 serving as a liquid application means for applying treatment liquid to the sheet material P is disposed upstream of the conveying path of the printing unit 20.

The pretreatment section 50 includes a treatment liquid container 55 that contains treatment liquid 54, a pumping roller 51 that pumps up the treatment liquid 54, an application roller 52 that applies (applies) the treatment liquid 54 to the sheet material P, and an opposing roller 53 that faces the application roller 52 with the sheet material P sandwiched between them. Examples of the treatment liquid 54 include a treatment liquid that reacts with liquid to suppress bleeding.

After the treatment liquid 54 is applied to the underside of the sheet material P by the application roller 52, the sheet material P is turned upside down and transported to the pair of registration rollers 21. After passing through the pair of registration rollers 21, the sheet material P is transported with the surface to which the treatment liquid 54 has been applied facing the discharge unit 28, and liquid is applied from the discharge unit 28.

Next, the portion related to the heating control in the heating device according to the second embodiment of the present invention will be described with reference to Figs. 10 and 11. Fig. 10 is a block diagram of the portion related to the control, and Fig. 11 is an explanatory diagram of an example of a table stored in the storage means.

In this embodiment, the operation means 801 inputs the basis weight or thickness information of the sheet material P to be used, as in the first embodiment.

The liquid application setting means 802 sets the application of the treatment liquid (whether or not to apply, and the amount of application) by the pre-treatment unit 50. In this embodiment, information regarding whether or not to apply the treatment liquid 54 set by the application setting means 802 is provided to the heating control means 901 as information regarding the sheet material P.

As shown in FIG. 11, the storage means 902 stores a table that lists information on whether or not the treatment liquid 54 is applied to the sheet material P, the basis weight or thickness of the sheet material P, and information on the heating direction of the first heating means 301.

In this embodiment, when no coating is applied, similar to the first embodiment, the heating direction of the first heating means 301 is direction A when the basis weight is small (thin paper), and the heating direction of the first heating means 301 is direction B when the basis weight is large (thick paper). When coating is applied, the heating direction of the first heating means 301 is direction B regardless of the basis weight (thickness).

The heating control means 901 reads out a table from the storage means 902 based on the information on the basis weight or thickness of the sheet material P input from the operation means 801 and the information on whether or not coating is performed input from the coating setting means 802, and controls the driving of the heating direction driving unit 315 to control the heating direction (posture) of the first heating means 301.

The heating control means 901 also controls the heating of the sheet material P by the first heating means 301 and the heating of the sheet material P by the second heating means 302.

The application control means 903 controls the application operation by the application means 501 (pretreatment unit 50) when applying the treatment liquid 54 according to the settings of the application setting means 802.

Next, the heating direction (posture) control of the first heating means 301 by the heating control means 901 will be described with reference to the flow chart in FIG. 12.

The operator sets whether or not to apply coating using the coating setting means 802 (S11). Then, the operator sets the basis weight or thickness of the sheet material P using the operation means 801 (S12).

The heating control means 901 takes in the information on whether or not coating is performed, which is set by the coating setting means 802, and the information on the basis weight or thickness of the sheet material P, which is set by the operation means 801, and reads the table stored in the memory unit 92 (S13).

Then, the heating control means 901 switches the heating direction of the first heating means 301 using the heating direction driving unit 315 based on the loaded table.

In other words, the heating control means 901 determines whether application is occurring (S14).

At this time, if no coating is applied, it is determined whether the sheet material P is thin paper or thick paper (S15).

Here, when the sheet material P is thin paper, the heating control means 901 sets the heating direction of the first heating means 301 to direction A, i.e., the direction in which the sheet material P is heated before being handed over to the conveyor belt 331 (S16).

In contrast, when the sheet material P is thick paper, the heating control means 901 sets the heating direction of the first heating means 301 to direction B, i.e., the direction just before the entrance of the second heating means 302, in which the sheet material P being transported by the transport belt 331 is heated (S17).

If coating is present, the process proceeds to step S17, and the heating control means 901 sets the heating direction of the first heating means 301 to direction B, i.e., the direction in front of the entrance of the second heating means 302, in which the sheet material P being transported by the transport belt 331 is heated.

In this way, when coating is performed, the heating direction of the first heating means 301 is set to direction B regardless of the basis weight or thickness of the sheet material P.

In other words, when the treatment liquid 54 is applied, the ink applied to the sheet material P has the characteristic of being less likely to flow, so the color unevenness described above does not occur whether the paper is thick or thin. Instead, the amount of liquid on the sheet material P increases by the amount of treatment liquid 54 applied, which tends to increase the amount of drying heat.

Therefore, the heating direction of the first heating means 301 is set to direction B, so that the sheet material P being transported by the transport belt 331 is heated just before the entrance of the second heating means 302, and then heating is performed by the second heating means 302 immediately after the sheet material P is heated. This makes it possible to increase the peak temperature of the ink and promote drying.

Next, a heating device according to a third embodiment of the present invention will be described with reference to FIG. 13. FIG. 13 is an explanatory diagram for explaining the heating device.

In this embodiment, the system includes a conveyor belt 331 as a conveying means for conveying the sheet material P opposite the second heating means 302, and a transfer means 304 that is located upstream of the conveyor belt 331 in the sheet material conveying direction and transfers the sheet material P toward the conveyor belt 331.

The transfer means 304 is provided with a transfer conveyor belt 341 as a transfer conveyor means disposed between the transfer cylinder 27 and the conveyor belt 331. The transfer conveyor belt 341 is stretched between a drive roller 342 and a driven roller 343, and moves in a circular motion by driving the drive roller 342. The transfer belt 341 can convey the sheet material P by sucking or adsorbing it. The transfer belt 341 may also have the same configuration as the conveyor belt 331.

In this embodiment, the first heating means 301 is also arranged so that the heating direction (the direction in which radiant heat is blown from the first heating means 301) can be changed. In other words, the first heating means 301 can be changed between a position in which the heating direction is direction A as shown in FIG. 13(a) (the position shown by the solid line in FIG. 1) and a position in which the heating direction is direction B as shown in FIG. 13(b) (the position shown by the virtual line in FIG. 1).

When the first heating means 301 is oriented so that the heating direction is in the direction A, the sheet material P is heated upstream of the transfer means 304. In other words, the sheet material P is heated before it is transferred from the transfer cylinder 27 to the transfer means 304.

When the first heating means 301 is oriented so that the heating direction is in the direction B, the sheet material P is heated after it is transferred from the transfer cylinder 27 to the transfer conveyor belt 341 of the transfer means 304 and before it faces the second heating means 302. In other words, the sheet material P being transferred by the transfer means 304 is heated before the entrance of the second heating means 302.

Next, a heating device according to a fourth embodiment of the present invention will be described with reference to FIG. 14. FIG. 14 is a side view of the heating device.

The heating device 300 has a heat irradiation section 302A and an ultraviolet irradiation section 302B as the second heating means 302.

The heat irradiation unit 302A has a housing 320A and multiple heat irradiation means 322A composed of IR heaters arranged along the conveying direction. The heat irradiation means 322A irradiates infrared rays to heat the sheet material P being conveyed by the suction conveying mechanism 303. The heat irradiation unit 302A is equipped with a temperature detection means 323A that detects the temperature of the heat irradiation means 322A.

The ultraviolet ray irradiation unit 302B has a plurality of ultraviolet ray irradiation means 322B arranged along the conveying direction within the housing 320B. The ultraviolet ray irradiation means 322B irradiates ultraviolet rays to heat the sheet material P being conveyed by the suction conveying mechanism unit 303.

In this way, in the conveying direction of the sheet material P, the heat irradiation means 322A is disposed upstream and the ultraviolet irradiation means 322B is disposed downstream.

Next, a heating device according to a fifth embodiment of the present invention will be described with reference to FIG. 15. FIG. 15 is a side view of the first heating means of the heating device.

The hot air blowing means 311 of the first heating means 301 includes an infrared heater 312 capable of radiating heat, an air blowing means 313 such as a fan, and an air blowing guide 314 that forms an air outlet.

The air blowing guide 314 can be displaced between the position shown by the solid line and the position shown by the virtual line. When the air blowing guide 314 is in the position shown by the solid line, the heating direction (hot air blowing direction) is direction A, and when it is in the position shown by the virtual line, the heating direction (hot air blowing direction) is direction B.

In other words, in this embodiment, instead of changing the overall position of the first heating means 301, the heating direction is switched by changing the direction in which hot air is blown out by the air blowing guide (blowout guide means) 314.

This makes it easy to change the heating direction.

REFERENCE SIGNS LIST 1 Printing device 10 Carry-in section 20 Printing section 21 Sheet conveying device 25 Liquid ejection section 27 Transfer cylinder 28 Ejection unit 30 Drying section 31 First drying means (first heating means)
32 Second drying means (second heating means)
33 Suction conveying mechanism 300 Heating device 301 First heating means 302 Second heating means 303 Suction conveying mechanism 304 Transfer means 331 Conveyor belt

Claims (14)

A first heating means for heating the sheet material to which the liquid has been applied;
A second heating means disposed downstream of the first heating means in a sheet conveying direction;
a transport means for transporting the sheet material toward the second heating means ,
the first heating means is capable of changing a heating direction between a direction for heating the sheet material upstream of the transport means and a direction for heating the sheet material being transported by the transport means,
A heating device characterized by having a means for controlling the heating direction of the first heating means based on information about the sheet material , to a direction for heating the sheet material upstream of the transport means, or a direction for heating the sheet material being transported by the transport means. 2. The heating device according to claim 1, wherein the transport means also serves as a transport means for transporting the sheet material opposite to the second heating means. The heating device according to claim 1, characterized in that the transfer means is a delivery transport means that transports the sheet material toward the transport means, upstream in the sheet material transport direction of the transport means that transports the sheet material opposite the second heating means. 4. The heating device according to claim 1, wherein the information about the sheet material is a thickness or a basis weight of the sheet material. 5. The heating device according to claim 1, wherein the information about the sheet material is information about whether or not a treatment liquid has been applied to the sheet material. The control means includes:
When the treatment liquid is being applied, the heating direction of the first heating means is set to a direction in which the sheet material being transported by the transport means is heated;
When the treatment liquid is not applied, the heating direction of the first heating means is set to a direction for heating the sheet material upstream of the transport means, or a direction for heating the sheet material being transported by the transport means, based on the thickness or basis weight of the sheet material.
Take control
6. The heating device according to claim 5. 7. The heating device according to claim 1, wherein the first heating means is capable of changing its position. 7. The heating device according to claim 1, wherein the first heating means comprises a heat generating means and an air blowing means, and the air blowing direction is changeable. The control means changes whether the heating of the sheet material by the first heating means is started upstream of the transport means or after the transport means starts transporting the sheet material, based on information about the sheet material.
9. The heating device according to claim 1, wherein the heating device is a heater. The heating device according to claim 9, characterized in that when heating of the sheet material by the first heating means is started upstream of the transporting means, the liquid temperature of the sheet material temporarily drops before it is transported to the second heating means. The heating device described in claim 10, characterized in that when heating of the sheet material by the first heating means is started after the transport means has begun to transport the sheet material, the liquid temperature of the sheet material after heating by the second heating means is higher than when heating is started upstream of the transport means. A heating device as described in any one of claims 9 to 11, characterized in that when heating of the sheet material by the first heating means is started upstream of the transport means, the transport distance over which the sheet material is heated by the first heating means and then heated by the second heating means is longer than when heating is started after the transport means has begun to transport the sheet material. A drying device comprising the heating device according to any one of claims 1 to 12. A liquid application means for applying a liquid to the sheet material;
A liquid ejection device comprising: a heating device according to any one of claims 1 to 12 ; or a drying device according to claim 13.

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