WO2023243565A1

WO2023243565A1 - Dryer, image formation device, and image formation method

Info

Publication number: WO2023243565A1
Application number: PCT/JP2023/021586
Authority: WO
Inventors: 剛浦上
Original assignee: コニカミノルタ株式会社
Priority date: 2022-06-17
Filing date: 2023-06-09
Publication date: 2023-12-21

Abstract

A dryer, an image formation device, and an image formation method which are capable of heightening the efficiency of drying an ink on a medium. The dryer comprises: an irradiation part whereby the ink-bearing surface of a medium on which an ink has been applied is irradiated with energy when the medium is being conveyed; and a support member disposed so as to face the irradiation part and having a supporting surface which supports the medium from the back-surface side reverse from that surface of the medium, the supporting surface having a mirror surface. For example, the supporting surface has a curved surface which is bent so as to protrude toward the irradiation part in a plan view including the conveyance direction of the medium.

Description

Drying device, image forming device, and image forming method

The present invention relates to a drying device, an image forming device, and an image forming method.

For example, a drying device is known that applies droplets (ink) to a recording medium such as paper and dries the ink on the recording medium at a destination where the recording medium is transported.

For example, Patent Document 1 discloses a drying device that dries continuous paper (media) coated with ink and conveyed, which includes a heating roller that contacts the continuous paper and heats the continuous paper, and a heating roller that dries the continuous paper (media) coated with ink and conveyed. An apparatus is described that includes an infrared light heater that irradiates infrared light onto the continuous sheet of paper to heat it while the continuous sheet of paper moves from the upstream side of the heating roller to the downstream side of the heating roller.

Japanese Patent Application Publication No. 2019-177701

By the way, in the drying device described in Prior Document 1, even if irradiation is performed with a peak wavelength matching the absorption peak wavelength of the ink, the amount that passes through the ink and the media is absorbed or reflected by the heating roller. The reflected infrared light will be irradiated onto the ink again, but the drying device described in Prior Document 1 does not mention the surface condition of the heating roller. For example, if the heating roller has a large surface roughness, In many cases, the irradiated infrared light is not highly reflected and is absorbed by the heating roller and does not act on the ink, resulting in a problem that the drying efficiency of the ink on the media is reduced.

An object of the present invention is to provide an apparatus that can increase the drying efficiency of ink on media.

In order to achieve the above object, the drying device in the present invention includes:
an irradiation unit that irradiates energy to a surface of the medium to which the ink is applied at a conveyance destination of the medium to which the ink is applied;
a support member that is arranged to face the irradiation unit and has a support surface that supports the medium from a back side opposite to the front surface;
Equipped with
The support surface has a mirror surface.

The image forming apparatus according to the present invention includes:
a primer ink discharge section for discharging primer ink containing a flocculant;
a color ink ejection unit for ejecting color ink containing a colorant;
The above drying device,
Equipped with

The image forming method in the present invention includes:
a step of applying ink to the surface of the media to form an image;
Applying energy to the surface of the medium while contacting the back surface of the medium opposite to the front surface with a temperature control unit for controlling the temperature, and absorbing the energy transmitted through the medium and the ink on the medium. a step of drying the image by reflecting it on a mirror surface provided in the temperature control unit,
In the step of drying the image, infrared light with a wavelength of 0.8 μm or more and 3.0 μm or less is irradiated with an irradiance of 30 kW/m ² or more, or ultraviolet light with a wavelength of 200 nm or more and 410 nm or less is irradiated with an irradiance of 1 W/m ² or more. Irradiate with

According to the present invention, it is possible to increase the drying efficiency of ink on media.

1 is a side view showing a schematic configuration of an image forming apparatus according to an embodiment. 1 is a block diagram showing the main functional configuration of an image forming apparatus according to an embodiment. FIG. FIG. 3 is a side view showing the relationship between a backup roller and media according to the present embodiment. FIG. 3 is an enlarged side view showing the relationship between the backup roller and the irradiation section according to the present embodiment. FIG. 3 is a side view showing a schematic configuration of an image forming apparatus according to a modification of the present embodiment.

Hereinafter, an inkjet image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a schematic configuration of an image forming apparatus 1 according to the present embodiment. Further, FIG. 2 is a block diagram showing the main functional configuration of the image forming apparatus 1. As shown in FIG.

The image forming apparatus 1 includes an image forming apparatus main body 2 that applies ink (droplets) onto the surface of a medium S, which is continuous paper, using an inkjet method, and an image forming apparatus main body 2 disposed downstream of the image forming apparatus main body 2 in the conveying direction of the medium S. , an irradiation unit 30 that irradiates the surface of the media S with infrared light energy, and a heating unit 60. Note that in the following description, ink may be referred to as an "ink image" or "image." Moreover, the conveyance direction of the media S is simply referred to as the "conveyance direction." In addition, a planar view including the transport direction is simply referred to as a "planar view." In this embodiment, this corresponds to the plan view depicted in FIG. Further, the surface of the medium S may be referred to as an "image forming surface."

(Image forming apparatus main body 2)
The image forming apparatus main body 2 includes a head unit 10 in which an inkjet head 102 and the like (see FIG. 2) are mounted, and a media S for transporting the media S from the upstream side of the image forming apparatus main body 2 to the downstream side of the image forming apparatus main body 2. A conveyance section 20 is provided.

(Transport unit 20)
The conveyance unit 20 includes a plurality of conveyance rollers 21, a backup roller 22 (corresponding to the "support member" of the present invention), a drive roller (not shown), etc., which are arranged at appropriate positions on the conveyance path. FIG. 1 shows two conveyance rollers 21L and 21R among the plurality of conveyance rollers 21.

The conveyance roller 21L is arranged on the upstream side of the image forming apparatus main body 2 in the conveyance direction (on the left side in FIG. 1). The conveyance roller 21R is disposed on the downstream side of the image forming apparatus main body 2 in the conveyance direction (on the right side in FIG. 1). A medium S is stretched between the transport roller 21L and the transport roller 21R. The back surface of the media S is in contact with the outer circumferential surface of each of the transport roller 21L and the transport roller 21R. As a result, when the media S is transported, a frictional force is generated between the respective outer circumferential surfaces of the transporting roller 21L and the transporting roller 21R and the back surface of the media S, and this frictional force causes the transporting roller 21L and the transporting roller 21R to Each of them is driven by the media S and becomes rotatable.

The backup roller 22 is disposed on the downstream side of the conveyance roller 21R in the conveyance direction. The outer peripheral surface 22a of the backup roller 22 has a support surface 22b that supports the media S. The support surface 22b has a curved surface. The curved surface is arranged to face the irradiation section 30. The curved surface is curved so as to protrude from the back surface side of the medium S toward the irradiation unit 30 side in a plan view including the transport path. As a result, the media S comes to follow the curved surface, and the media S is prevented from rising from the curved surface.

FIG. 3 is a side view showing the relationship between the backup roller 22 and the media S according to the present embodiment. As shown in FIG. 3, a media S is wound around the outer peripheral surface 22a. In plan view, the length of the support surface 22b and the circumferential length of the curved surface match. In other words, in plan view, the length of the curved surface is 100% of the circumferential length of the support surface 22b.

Since the length of the curved surface is 100% of the length of the support surface 22b and the media S does not rise from the curved surface, a contact area for contacting the back surface of the media S is ensured on the curved surface. As a result, when the media S is transported, a frictional force of a predetermined value or more is generated between the support surface 22b and the back surface of the media S. The frictional force makes it possible to prevent the backup roller 22 and the media S from slipping against each other, so that the backup roller 22 can follow the media S and rotate together. In this embodiment, the wrapping angle of the media S wrapped around the outer circumferential surface 22a is 120 degrees (°) or more. As a result, the frictional force generated between the support surface 22b and the back surface of the media S becomes equal to or greater than a predetermined value.

Further, the support surface 22b (outer peripheral surface 22a) has a mirror surface. On the mirror surface, infrared light that is irradiated from the irradiation unit 30 onto the image forming surface (surface) of the medium S and transmitted through the ink and the medium S is reflected.

The mirror surface is arranged corresponding to the irradiation range, which is the range in which the image forming surface (surface) of the medium S is irradiated with infrared rays from the irradiation unit 30. Note that the irradiation range changes based on the image forming conditions when an ink image is formed on the medium S. No matter how the irradiation range changes, in order to make the mirror surface correspond to the irradiation range, the mirror surface is arranged according to the maximum value of the irradiation range that corresponds to all of the image forming conditions. As described above, the ink on the media S is irradiated again with the infrared light reflected by the mirror surface, so that the drying efficiency of the ink on the media S can be increased.

In the present embodiment, the mirror surface is arranged over the entire range of the outer peripheral surface 22a of the backup roller 22 in the width direction, and is arranged over the entire circumference of the outer peripheral surface 22a of the backup roller 22.

The drying efficiency of the ink on the media S changes depending on the reflectance of the mirror surface. Here, the "reflectance of the mirror surface" refers to the ratio of the energy of the infrared light reflected by the mirror surface to the energy (light intensity) of the infrared light irradiated onto the image forming surface. Furthermore, the reflectance of a mirror surface changes depending on the surface roughness of the mirror surface. The arithmetic mean roughness Ra of the mirror surface is set based on simulation and experimental results from the viewpoint of drying efficiency for ink. In this embodiment, the arithmetic mean roughness Ra of the mirror surface is 0.1 μm or less, more preferably 0.05 μm or less.

The mirror surface can be achieved by an etching process that dissolves the support surface 22b using the corrosive action of a chemical such as an etching solution, a hairline process that polishes the support surface 22b in a certain direction with an abrasive belt, or by adding circular irregularities to the support surface 22b. Processed using a spin process.

A drive roller (not shown) is arranged downstream of the backup roller 22 in the conveyance direction. Under the control of the control unit 40, the driving force of a drive motor (not shown) of the conveyance drive unit 51 (see FIG. 2) is transmitted to the drive roller. This causes the drive roller to rotate. A media S is wound around the drive roller. Moreover, the media S is in contact with the outer peripheral surface of the drive roller. As a result, when the drive roller rotates, a frictional force is generated between the outer circumferential surface of the drive roller and the media S, and this frictional force allows the media S to be conveyed to the rotating drive roller.

(Head unit 10)
The image forming apparatus 1 in this embodiment includes a head unit 10 (corresponding to the "color ink ejecting section" of the present invention) that ejects each of the four colors of ink. The head unit 10 is arranged to face the image forming surface (surface) of the medium S stretched between the transport roller 21L and the transport roller 21R. The head unit 10 forms an ink image on the medium S by ejecting ink (droplets) onto the image forming surface of the medium S from nozzle openings provided on the ink ejection surface.

In one specific example, as shown in FIG. 1, two or more head units 10 corresponding to two or more color inks are arranged in a predetermined order and at a predetermined interval from the upstream side in the transport direction. For example, in the case of four color inks, four head units 10 corresponding to the four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are installed from the upstream side in the transport direction. The colors are arranged in the order of Y, M, C, and K at predetermined intervals.

The color ink only needs to contain at least a colorant, and for example, it can be an ink containing a colorant, a dispersant for dispersing the colorant, fine resin particles, and a solvent. Examples of colorants include known pigments. The colorant may be either an organic pigment or an inorganic pigment. When using a primer ink, which will be described later, together with a colored ink, the colorant is preferably an anionic pigment. When the colorant is an anionic pigment, it is easily fixed by the primer ink described below. Further, the average particle diameter of the pigment in the color ink is preferably 50 nm or more and less than 200 nm.

When each of two or more color inks is applied to the media S, each of the two or more color inks absorbs infrared light with a specific wavelength selected from wavelengths of 0.8 μm to 3.0 μm. Contains coloring agents with different ratios. In this case, when infrared light is irradiated from the irradiation unit 30, the colorant in the ink image absorbs the infrared light and its temperature increases. Then, heat is transferred to the solvent by thermal conduction, and the solvent evaporates. This makes it possible to dry the ink on the media S.

The image forming apparatus 1 also includes a head unit 10 (corresponding to the "primer ink ejecting section" of the present invention) that ejects primer ink containing an aggregating agent. The head unit 10 that ejects primer ink may be provided separately from the head unit 10 that ejects color ink (for example, the head unit 10 that ejects black color ink), or may be provided integrally with the head unit 10 that ejects color ink. When provided separately, the head unit 10 that ejects primer ink is placed on the upstream side, and the head unit 10 that ejects color ink is placed on the downstream side. However, the head unit 10 that ejects primer ink may be placed downstream of the head unit 10 that ejects color ink.

The primer ink only needs to contain at least a flocculant, and for example, it can be an ink containing a flocculant and a solvent. According to such a primer ink, bleeding is unlikely to occur even if color ink is applied without drying after application of the primer ink. Therefore, there is no need for a drying or curing process before applying the color ink, and an ink image can be formed in a simple process. Furthermore, when a primer ink having such a composition is used, the ink image is unlikely to bleed even if it takes a long time to dry after the image is formed. Therefore, high quality images can be obtained. Note that the primer ink may further contain a surfactant, a crosslinking agent, an antifungal agent, a bactericidal agent, etc. as necessary, but since the primer ink does not contain resin particles, the primer ink has thickening properties. It becomes difficult.

When the ink image includes primer ink and color ink, even if the time from the formation of the ink image to drying is prolonged, the ink image is unlikely to smear, and a desired high-quality ink image can be obtained. Further, when the ink image includes primer ink and color ink, the ink image is easily retained on the medium S by applying the primer ink to the medium S and then ejecting the color ink onto the undried primer ink. Therefore, the head unit 10 can be placed sufficiently away from the irradiation section 30 and the heating section 60. Further, it is possible to prevent the nozzle openings of the head unit 10 from clogging and the ink from deteriorating due to heat when drying the color ink.

Each head unit 10 includes an inkjet head 102 (see FIG. 2). The inkjet head 102 is provided with a plurality of recording elements each having a pressure chamber for storing ink, a piezoelectric element provided on the wall of the pressure chamber, and a nozzle. In this recording element, when a drive signal that causes the piezoelectric element to perform a deforming operation is input, the pressure chamber is deformed by the deformation of the piezoelectric element, the pressure within the pressure chamber changes, and ink is ejected from a nozzle communicating with the pressure chamber.

The arrangement range of the nozzles included in the inkjet head 102 in the direction perpendicular to the plane of the paper in FIG. covers.

The head unit 10 is used with its position fixed relative to the medium S during image formation. That is, this image forming apparatus 1 is a single-pass type inkjet image forming apparatus.

In one specific example, as ink ejected from the inkjet head 102 onto the medium S, an ink ( water-based ink) is used. As such a water-based ink, an ink containing a water-soluble organic solvent such as alcohol, for example, an aqueous dye ink or a solvent water-based ink can be used.

In addition, as the media S, in addition to paper such as plain paper and coated paper, various media capable of fixing ink that has landed on the image forming surface (surface), such as fabric or resin, can be used.

Next, other main functional configurations of the image forming apparatus 1 will be described with reference mainly to FIG. 2. The image forming apparatus 1 includes a head drive section 101 and an inkjet head 102 included in the head unit 10, a control section 40, a transport drive section 51, and an input/output interface 52. Although not shown, the image forming apparatus 1 can include an operation display unit such as a touch panel for accepting user operations and displaying various settings and states of the image forming apparatus 1.

The head drive unit 101 controls the inkjet head 102 by outputting a drive signal to the recording element of the inkjet head 102 at an appropriate timing to cause the piezoelectric element to perform a deforming operation according to the image data based on the control of the control unit 40. An amount of ink corresponding to the pixel value of image data is ejected from the nozzle.

(Control unit 40)
The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various calculation processes. Further, the CPU 41 centrally controls the entire operation of the image forming apparatus 1 .

The RAM 42 provides a working memory space for the CPU 41 and stores temporary data. Note that the RAM 42 may include nonvolatile memory.

The ROM 43 stores various control programs and setting data executed by the CPU 41. Note that instead of the ROM 43, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores a print job (image forming instructions including various user setting information such as the number of copies to be printed) input from the external device 200 via the input/output interface 52 and image data related to the print job. . As the storage unit 44, for example, a HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may also be used in combination.

The conveyance drive section 51 supplies a drive signal to the above-mentioned drive motor and the like based on a control signal supplied from the control section 40 to rotate a drive roller (not shown) at a predetermined speed and timing.

The input/output interface 52 mediates the transmission and reception of data between the external device 200 and the control unit 40. The input/output interface 52 is configured of, for example, one of various serial interfaces, various parallel interfaces, or a combination thereof.

The external device 200 is, for example, a personal computer, and supplies print jobs, image data, etc. to the control unit 40 via the input/output interface 52.

(irradiation section 30)
The irradiation unit 30 is arranged at a position radially away from the rotation axis of the backup roller 22. Thereby, the irradiation unit 30 is arranged to face the support surface 22b of the backup roller 22. The irradiation unit 30 is an infrared light irradiation unit that includes a light source (heat source) that irradiates infrared light onto the image forming surface of the medium S on which an image is formed (that is, ink lands) by the inkjet head 102 of the head unit 10. .

In the configuration example shown in FIG. 1, the irradiation unit 30 is an infrared light irradiation unit that forms part of the fixing unit and irradiates the image forming surface (surface) of the medium S with infrared light as described above. The ink on the media S is dried and fixed on the media S.

In the infrared light irradiation section, one or more light sources are arranged so that the entire width direction of the medium S can be irradiated with infrared light. Here, the "width direction" is a direction perpendicular to the conveyance direction of the medium S. However, depending on the formation position of the ink image, the shape of the medium S, the type of the medium S, etc., the heat source may be arranged so as to irradiate only a part of the medium S in the width direction with infrared light.

The light source of the infrared light irradiation section is placed with a gap between it and the media S. The distance between the light source of the infrared light irradiation section and the medium S may be constant, or may change continuously or intermittently. However, the distance between the light source of the infrared light irradiation section and the medium S is preferably 3 cm or more and 20 cm or less, and more preferably 5 cm or more and 15 cm or less. If the distance between the light source of the infrared light irradiation section and the medium S is 5 cm or more, it is difficult for the medium S to come into contact with the light source even if the medium S is bent. On the other hand, if the distance is 20 cm or less, the medium S can be efficiently irradiated with infrared light from the light source of the infrared light irradiation section.

Here, the wavelength of the infrared light irradiated from the infrared light irradiation part may be 0.8 μm or more and 3.0 μm or less, preferably 0.8 μm to 2.5 μm, and 1.7 μm to 2.5 μm. More preferred. If the wavelength emitted by the infrared light irradiation section is within this range, the temperature of the ink can be increased in a short time. Furthermore, for example, if the wavelength of the infrared light is set to 1.7 μm to 2.5 μm, it is possible not only to increase the ink temperature in a short time, but also to suppress the difference in the absorption rate of infrared light between multiple types of ink. Can be done.

Further, the output of infrared light (irradiance) from the infrared light irradiation part may be 30kW/ ^m2 or more, preferably 40kW/ ^m2 or more and 350kW/ ^m2 or less, and 60kW/ ^m2 or more and 150kW/m2 or more. m ² or less is more preferable. If the output from the infrared light irradiation section is within this range, it becomes possible to dry the ink image in about 10 seconds, for example. Note that the output of infrared light can be specified from the specifications of the light source.

Further, the light source of the infrared light irradiation section is not particularly limited as long as it can emit infrared light at the above wavelength and output (irradiance), and any known light source can be used. Further, the light source may be a point light source or a linear light source. Examples of such light sources include halogen lamp heaters, quartz tube heaters, carbon heaters, and the like. Further, the number of light sources included in the infrared light irradiation section is not particularly limited, and is appropriately selected according to the width and length of the area to be irradiated with infrared light.

Further, the control unit that controls the infrared light irradiation unit may be capable of, for example, monitoring the temperature of the light source or adjusting the amount of power supplied to the light source according to the temperature of the light source. This is similar to the control section of a known infrared light irradiation section. Furthermore, a cooling section (not shown) may be provided for cooling the infrared light irradiation section. The cooling unit may be configured as long as it can cool the light source and its surroundings in order to control the temperature of the infrared light irradiation unit from rising excessively, and may be, for example, a blower, a cooling chiller, etc. .

(Heating part 60)
The heating section 60 has a heat source. A heat source of the heating section 60 is arranged inside the backup roller 22. The heat source of the heating unit 60 is controlled based on the temperature measured by a temperature sensor (not shown). Thereby, the temperature of the outer peripheral surface 22a of the backup roller 22 is heated to a predetermined temperature, and since the support surface 22b of the backup roller 22 is in contact with the back surface of the medium S, the medium S is warmed. Therefore, according to the heating unit 60, it is possible to dry the ink image and fix it on the medium S in a short time. The backup roller 22 and the heating section 60 correspond to the "temperature control section" of the present invention.

The support surface 22b (outer peripheral surface 22a) that contacts the back surface of the media S is made of a highly thermally conductive member or the like in order to efficiently transmit thermal energy from the heat source of the heating section 60 to the media S. The material constituting the support surface 22b is preferably metal, such as copper, aluminum, or a composite thereof. The width of the support surface 22b (outer peripheral surface 22a) is not particularly limited, and may be at least as long as the area irradiated with energy by the irradiation section 30. However, it is preferable that the width of the area where the support surface 22b (outer circumferential surface 22a) and the medium S contact is equal to or larger than the width of the medium S. Further, the length of the area where the support surface 22b (outer peripheral surface 22a) and the medium S contact each other (the distance in the direction parallel to the conveying direction of the medium S) is at least the length of the area irradiated with energy by the irradiation unit 30. is preferred. Further, it is preferable that the back surface of the medium S and the support surface 22b are in contact with each other in substantially the entire region to which energy is irradiated by the irradiation unit 30.

Examples of the heat source of the heating section 60 include a known heater. The backup roller 22 is provided with a heat source and a temperature adjustment mechanism.

Thus, in the configuration example shown in FIG. 1, each of the irradiation section 30 and the heating section 60 serves as a drying device that dries the ink applied to the image forming surface (surface) of the medium S and fixes it on the medium S. Responsible for

Next, the relationship between the backup roller 22 and the irradiation section 30 according to the present embodiment will be explained with reference to FIG. 4. FIG. 4 is an enlarged side view showing the relationship between the backup roller 22 and the irradiation section 30 according to the present embodiment. In addition, in FIG. 4, the gap between the mirror surface of the backup roller 22 and the media S is emphasized. Further, in FIG. 4, the direction of the infrared light that has passed through the ink and the media S is shown by dotted hatching arrows. Further, in FIG. 4, infrared light reflected by the mirror surface of the backup roller 22 is shown by diagonally hatched arrows.

As shown in FIG. 4, in order to dry the ink on the medium S, infrared light is irradiated from the irradiation unit 30 in the direction of the image forming surface (surface) of the medium S. The infrared light emitted from the irradiation unit 30 is mainly divided into infrared light absorbed by the ink and infrared light transmitted through the ink and the media S. The energy of the infrared light absorbed by the ink contributes to the drying of the ink.

The infrared light that has passed through the ink and the media S reaches the mirror surface of the backup roller 22. The infrared light that reaches the mirror surface is mainly composed of infrared light that is absorbed by the mirror surface, infrared light that is reflected by the mirror surface and irradiated onto the ink, and infrared light that is reflected from the mirror surface and is not irradiated onto the ink. It is divided into The infrared light is reflected by a mirror surface and irradiated onto the ink, and the energy of the infrared light absorbed by the ink contributes to the drying of the ink.

In the configuration shown in FIG. 4 showing the relationship between the backup roller 22 and the irradiation section 30, the energy of the infrared light from the irradiation section 30 is once irradiated onto the ink on the media S, and is absorbed by the ink, thereby drying the ink. Contribute to That is, on the outward path of the infrared light, the energy of the infrared light absorbed by the ink contributes to the drying of the ink. Further, the energy of the infrared light transmitted through the ink and the media S is reflected by the mirror surface and absorbed into the ink again, thereby drying the ink. That is, even on the return path of the infrared light, the energy of the infrared light absorbed by the ink contributes to the drying of the ink. As described above, in the configuration shown in FIG. 4 in which infrared light is reflected by a mirror surface, the energy of the infrared light contributes to the drying of the ink in each of the forward and return paths of the infrared light. Drying efficiency can be increased.

(Effects of the drying device according to this embodiment)
The drying device according to the above embodiment includes an irradiation unit 30 that irradiates infrared light energy onto the surface of the media S to which the ink is applied, and an irradiation unit 30 facing the irradiation unit 30 at a conveyance destination of the medium S to which ink is applied. and a backup roller 22 having a support surface 22b that supports the media S from the back side opposite to the front surface, and the support surface 22b has a mirror surface.

According to the above configuration, the energy of the infrared light that has passed through the ink and the media S is reflected by the mirror surface and is irradiated onto the ink on the media S again, so it is possible to increase the drying efficiency for the ink on the media S. becomes. In addition, even when the media S has translucency, the energy of the infrared light that has passed through the media S is reflected on the mirror surface and is irradiated again to the ink on the media S, so the drying efficiency for the ink on the media S is increased. It becomes possible to raise the

Furthermore, in the drying device according to the embodiment described above, the support surface 22b has a curved surface that is curved so as to protrude toward the irradiation section 30 side when viewed from above. This creates tension in a predetermined direction on the media S, so the media S follows the curved surface, making it possible to prevent the media S from lifting up, and the heat of the backup roller is efficiently transferred to the media S, allowing it to dry. Increases efficiency.

Furthermore, the drying device according to the above embodiment further includes a heating section 60 that heats the backup roller 22. As a result, the backup roller 22 is heated, so that drying of the ink on the media S supported by the support surface 22b of the backup roller 22 is promoted.

Furthermore, in the drying device according to the embodiment described above, the backup roller 22 is a roller that is driven by the media S and made rotatable. As a result, the backup roller 22 rotates with the media S, so the backup roller 22 and the media S do not rub against each other, making the media S less likely to be damaged.

Furthermore, in the drying device according to the above embodiment, the wrapping angle at which the media S is wrapped around the backup roller 22 is 120 degrees or more. As a result, a frictional force greater than a predetermined value is generated between the backup roller 22 and the media S. The frictional force can prevent the backup roller 22 and the media S from slipping against each other, so the backup roller 22 can follow the media S and rotate together.

Furthermore, in the drying device according to the above embodiment, the arithmetic mean roughness Ra of the mirror surface is 0.1 μm or less, more preferably 0.05 μm or less. As a result, the reflectance of the infrared light reflected on the mirror surface becomes equal to or higher than a predetermined value, and the reflected infrared light is irradiated onto the ink on the media S again, so that the drying efficiency of the ink can be increased.

(Modified example)
Next, an image forming apparatus according to a modification of the present embodiment will be described with reference to FIG. 5. FIG. 5 is a side view showing a schematic configuration of an image forming apparatus according to a modification. In the following description of the modified example, configurations different from those of the above embodiment will be mainly explained, and the same configurations will be given the same reference numerals and explanations thereof will be omitted.

As shown in FIG. 5, the image forming apparatus 1 according to the modification includes a transport section 20 and irradiation sections 30 and 30A. The conveyance unit 20 includes conveyance rollers 21L and 21R, a backup roller 22, and a plate 23 (corresponding to the "support member" of the present invention).

The transport roller 21R is arranged upstream of the transport roller 21L in the transport direction. Each of the backup roller 22 and the plate 23 is arranged between the transport rollers 21L and 21R in the transport direction. The plate 23 is arranged on the downstream side of the backup roller 22 in the conveyance direction.

The head unit 10 is arranged to face the image forming surface (surface) of the medium S stretched between the transport roller 21L and the backup roller 22. The irradiation unit 30 is arranged to face the support surface 22b of the backup roller 22.

The plate 23 is arranged between the backup roller 22 and the conveyance roller 21R. The plate 23 has a curved surface that protrudes toward the irradiation section 30A side in plan view (plan view depicted in FIG. 5). As a result, tension in the flow direction DR1 is generated on the upstream side of the curved surface of the media S, and tension in the downstream direction DR2 is generated on the downstream side of the curved surface of the media S, so that the media S follows the curved surface. , it becomes possible to prevent the media S from lifting off the curved surface.

In the above embodiment, the backup roller 22 is the support member, whereas in the modified example, the plate 23 is the support member. Further, in the above embodiment, the length of the curved surface is 100% of the circumferential length of the support surface 22b in plan view. On the other hand, in the modified example, the length of the range in which the media S contacts the curved surface is 50% or more of the length of the curved surface in plan view. This allows the back surface of the medium S to easily slip on the curved surface 23b, making it difficult for the medium S to be damaged.

In the modified example, the ratio of the length of the curved surface to the length of the plate 23 in plan view is set from the viewpoint of preventing the media S from rising from the curved surface. The length of the curved surface is effectively used as a function to prevent the media S from floating up, and the length of the curved surface is not wasted, and the length of the plate 23 is also not wasted. It becomes difficult. Note that, in plan view, the curvature of the curved surface is also set from the viewpoint of preventing the media S from rising from the curved surface.

Furthermore, in the embodiment described above, the mirror surface is arranged over the entire circumference of the outer circumferential surface 22a of the backup roller 22. On the other hand, in the modified example, when the infrared light emitted from the irradiation unit 30A passes through the ink and the media S and reaches the plate 23 side, the infrared light at the plate 23 reaches the mirror surface. It only needs to be placed within the range.

Note that in the above embodiments and modifications, the irradiation section 30 is an infrared light irradiation section that irradiates infrared light from a light source, but the present invention is not limited to this. For example, instead of or together with the infrared light irradiation section, an ultraviolet light irradiation section that irradiates ultraviolet light from a light source or a laser irradiation section that irradiates laser light from a light source may be used. When the irradiation section 30 is an ultraviolet light irradiation section, for example, the wavelength of the ultraviolet light irradiated by the light source of the ultraviolet light irradiation section may be 200 nm or more and 410 nm or less. When using an LED, the wavelength is preferably 350 nm or more and 410 nm or less. When the wavelength of the ultraviolet light is 200 nm or more and 410 nm or less, the ultraviolet light is easily absorbed by the colorant contained in the ink, and as a result, the temperature of the ink can be increased in a short time. Further, the output (irradiance) of the light source of the ultraviolet light irradiation section may be 1 W/m ² or more.

Furthermore, each of two or more color inks may be applied to the media S, and each of the irradiation units 30 and 30A may be an ultraviolet light irradiation unit. For example, when two color inks are applied to the media S, each of the two color inks has a different absorption rate for ultraviolet light at a specific wavelength selected from a wavelength of 200 nm to 410 nm. Each of them may contain a coloring agent, and each of the irradiation units 30 and 30A may irradiate each with ultraviolet light having specific wavelengths different from each other. The colorant in the ink image absorbs the energy of the ultraviolet light, causing its temperature to rise. Heat is transferred to the solvent by thermal conduction, and the solvent evaporates. As described above, it becomes possible to dry the ink on the media S.

The light source of the ultraviolet light irradiation section is not particularly limited as long as it can emit ultraviolet light at the above wavelength and above output. Known light sources can be used. The light source may be a point light source or a linear light source. Examples of such light sources include halogen lamps and UV-LED (Light Emitting Diode) lamps. Specific examples of the UV-LED lamp include 300 nm LED, 375 nm LED, 395 nm LED, 410 nm LED, etc., which are appropriately selected according to the type of colorant included in the ink image (color ink). When drying an ink image containing multiple color inks, multiple types of LED lamps may be combined. Further, the number of light sources included in the infrared light irradiation section is not particularly limited, and is appropriately selected according to the width and length of the area to which ultraviolet light is irradiated.

In addition, the above-mentioned embodiments are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed as limited by these. That is, the present invention can be implemented in various forms without departing from its gist or main features.

The disclosure contents of the specification, drawings, and abstract contained in Japanese Patent Application No. 2022-098293 filed on June 17, 2022 are all incorporated into the present application.

The present invention is suitably used in an image forming apparatus equipped with a drying device that is required to increase the drying efficiency of ink on media.

1 Image forming apparatus 2 Image forming apparatus main body 10 Head unit 20 Conveyance section 21, 21L, 21R Conveyance roller 22 Backup roller 22a Outer peripheral surface 22b Support surface 23 Plate 30 Irradiation section 40 Control section 41 CPU
42 RAM
43 ROM
44 Storage unit 51 Conveyance drive unit 52 Input/output interface 60 Heating unit 101 Head drive unit 102 Inkjet head 200 External device S Media

Claims

an irradiation unit that irradiates energy to a surface of the medium to which the ink is applied at a conveyance destination of the medium to which the ink is applied;
a support member that is arranged to face the irradiation unit and has a support surface that supports the medium from a back side opposite to the front surface;
Equipped with
The support surface has a mirror surface.
drying equipment.
The support surface has a curved surface that is curved so as to protrude toward the irradiation unit in a plan view including the conveyance direction of the medium.
The drying device according to claim 1.
The support member is a roller that is rotatable by following the medium;
The drying device according to claim 1.
The wrapping angle at which the media is wrapped around the roller is 120 degrees or more;
The drying device according to claim 3.
further comprising a heating unit that heats the support member;
The drying device according to claim 1.
The support member includes a plate having the curved surface,
In the planar view, the length of the range in which the medium contacts the curved surface is 50% or more of the length of the curved surface;
The drying device according to claim 2.
The arithmetic mean roughness Ra of the mirror surface is 0.1 μm or less, more preferably 0.05 μm or less,
The drying device according to claim 1.
a primer ink discharge section for discharging primer ink containing a flocculant;
a color ink ejection unit for ejecting color ink containing a colorant;
The drying device according to claim 1;
An image forming apparatus comprising:
a step of applying ink to the surface of the media to form an image;
Applying energy to the surface of the medium while contacting the back surface of the medium opposite to the front surface with a temperature control unit for controlling the temperature, and absorbing the energy transmitted through the medium and the ink on the medium. a step of drying the image by reflecting it on a mirror surface provided in the temperature control unit,
In the step of drying the image, infrared light with a wavelength of 0.8 μm or more and 3.0 μm or less is irradiated with an irradiance of 30 kW/m2 or more, or ultraviolet light with a wavelength of 200 nm or more and 410 nm or less is irradiated with an irradiance of 1 W/m2 or more. do,
Image forming method.
In the step of forming the image,
a primer ink containing at least a flocculant;
applying a colored ink containing at least a coloring agent;
The image forming method according to claim 9.
In the step of forming the image,
Colorants with different absorption rates for infrared light at a specific wavelength selected from wavelengths of 0.8 μm to 3.0 μm, or ultraviolet light at a specific wavelength selected from wavelengths of 200 nm to 410 nm. Applying two or more colored inks each containing colorants with different absorption rates,
The image forming method according to claim 9.