JP2024044664A - Humidification device, image forming device, and liquid ejection device - Google Patents

Abstract

[Problem] Suppressing variation in the amount of humidifying liquid applied to a sheet. [Solution] A humidifying device that applies humidifying liquid to a sheet S by ejecting the humidifying liquid together with gas from an outlet 31a, the device is equipped with a gas pressure adjustment means 38 that adjusts the gas pressure of the gas ejected from the outlet 31a, and a liquid pressure adjustment means 39 that adjusts the liquid pressure of the humidifying liquid supplied to the outlet 31a, and adjusts both the gas pressure of the gas and the liquid pressure of the humidifying liquid when changing the amount of humidifying liquid ejected from the outlet 31a. [Selected Figure] Figure 4

Description

The present invention relates to a humidifying device, an image forming device, and a liquid ejecting device.

A technique is known in which a humidifying liquid is applied to the sheet to prevent the sheet from waviness (cockling).

For example, in Patent Document 1 (Japanese Patent No. 6149563), in order to suppress waviness caused by paper absorbing water from ink and partially expanding, humidification is applied to non-image areas on paper where ink is not ejected. It has been proposed to reduce the difference in paper expansion between the image area to which the ink is applied and the other non-image area by applying a transparent liquid to the paper.

By the way, as one means for discharging a liquid onto an object, there is a liquid discharging means that discharges a mist of liquid together with compressed gas from a discharge port. When such a liquid discharge means is used, the amount of liquid discharged is generally adjusted by adjusting the gas pressure of compressed gas or the liquid pressure of the supplied liquid. .

However, adjusting either the gas pressure or the liquid pressure changes not only the amount of liquid ejected but also the liquid spray pattern, resulting in variation in the amount of liquid ejected onto the target object. Therefore, when applying humidification liquid to a sheet, variation also occurs in the amount of liquid applied.

Therefore, an object of the present invention is to suppress variations in the amount of humidifying liquid applied to the sheet.

In order to solve the above-mentioned problems, the present invention provides a humidifying device that discharges a humidifying liquid together with gas from a discharge port to apply the humidifying liquid to a sheet, wherein the gas discharged from the discharge port and a liquid pressure adjusting means for adjusting the liquid pressure of the humidifying liquid supplied to the discharge port, the amount of the humidifying liquid discharged from the discharge port. When changing, both the gas pressure of the gas and the liquid pressure of the humidifying liquid are adjusted.

The present invention can reduce variation in the amount of moisturizing liquid applied to the sheet.

1 is a schematic configuration diagram of an inkjet image forming apparatus that is an embodiment of the present invention. 1 is a diagram showing a control system of an inkjet image forming apparatus according to an embodiment. FIG. 1 is a diagram showing the configuration of a drying device according to the present embodiment. It is a figure showing the composition of the humidification device concerning this embodiment. 11 is a graph showing the relationship between gas pressure, liquid pressure, and variation in liquid deposition amount when the liquid pressure is changed while the gas pressure is maintained constant in a two-fluid spray type liquid discharge means. It is a figure which shows an example of the nozzle with which a humidifier is equipped. FIG. 4 is a diagram showing an example of a spray range of a nozzle. 11 is a graph showing the relationship between the ejection amount and the ejection position of liquid ejected from a nozzle. It is a figure showing an example of arrangement of a nozzle. It is a figure showing an example of arrangement of a nozzle. FIG. 13 is a diagram showing another example of the nozzle arrangement. It is a figure which shows another example of arrangement|positioning of a nozzle.

The present invention will be described below using a humidifying device installed in an inkjet image forming apparatus as an example. In each drawing for explaining the present invention, constituent elements such as members and components having the same function or shape are given the same reference numerals as much as possible to distinguish them. Omitted.

FIG. 1 is a schematic diagram of an inkjet image forming apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the inkjet image forming apparatus 100 according to this embodiment includes a sheet supplying section 1 that supplies a sheet S for image formation, an image forming section 2 that forms an image on the sheet S, a drying section 3 that dries the sheet S, a humidifying section 4 that humidifies the sheet S, and a sheet recovery section 5 that recovers the sheet S. The inkjet image forming apparatus 100 according to this embodiment also includes a control section 6 (see FIG. 2) for controlling the sheet supplying section 1, the image forming section 2, the drying section 3, the humidifying section 4, and the sheet recovery section 5.

In the sheet supply section 1, a supply roller 11 on which a long sheet S is wound in a roll shape, and a conveyance roller 12 that conveys the sheet S are arranged. When the supply roller 11 rotates, the sheet S is fed out from the supply roller 11, and the fed out sheet S is conveyed to the image forming section 2 by the conveyance roller 12.

In the image forming unit 2, a plurality of liquid ejection heads 13Y, 13M, 13C, and 13K are arranged as liquid ejection units that eject ink, which is a liquid (first liquid), onto the sheet S, and a platen 14 is arranged as a guide member that guides the sheet S being transported. The platen 14 is arranged below each of the liquid ejection heads 13Y, 13M, 13C, and 13K, and guides the sheet S supplied from the sheet supply unit 1 to a position facing each of the liquid ejection heads 13Y, 13M, 13C, and 13K. The plurality of liquid ejection heads 13Y, 13M, 13C, and 13K are, for example, liquid ejection head 13K that ejects black ink, liquid ejection head 13C that ejects cyan ink, liquid ejection head 13M that ejects magenta ink, and liquid ejection head 13Y that ejects yellow ink. Here, the ink used to form images is a liquid that contains colorant, a solvent, and crystalline resin particles dispersed in the solvent. The crystalline resin is a resin that undergoes a phase change when heated above a certain melting point, melting from a crystalline state into a liquid.

In the example shown in FIG. 1, from the upstream side in the conveyance direction of the sheet S, a liquid ejection head 13K for black ink, a liquid ejection head 13C for cyan ink, a liquid ejection head 13M for magenta ink, and a liquid ejection head 13M for yellow ink. Although they are arranged in the order of the liquid ejection heads 13Y, the arrangement is not limited to this order and may be in any other order. Further, the liquid ejection head is not limited to a configuration that supports four colors of liquid ink, and there may be a liquid ejection head that supports liquid ink of different colors.

When the sheet S is transported to the image forming unit 2, ink is ejected from each of the liquid ejection heads 13Y, 13M, 13C, and 13K onto the sheet S based on image data generated by the control unit 6, forming an image on the sheet S. In addition, ink may be ejected from any one of the multiple liquid ejection heads 13Y, 13M, 13C, and 13K to form a single-color image, or ink may be ejected from any two or three of the liquid ejection heads to form a two- or three-color image.

In the drying section 3, a drying device 20 is disposed for drying the sheet S to which ink has been applied. The drying device 20 has a heating drum 21, multiple heating rollers 22, multiple guide rollers 23, and multiple air blowing units 24. The heating drum 21 and the heating roller 22 are contact-type heating means that have a heat source such as a heater disposed inside and contact and heat the sheet S. In place of the contact-type heating means, a non-contact heating means such as a hot air generator that blows hot air onto the sheet to heat it may be used. The guide roller 23 is a guide member that guides the sheet S within the drying device 20. The air blowing unit 24 is a blowing means that blows air onto the sheet S. The air blown out from the air blowing unit 24 may be hot air or cold air.

When the sheet S on which the image has been formed is transported to the drying section 3, the sheet S is heated as it is transported while being in contact with multiple heating rollers 22 and a heating drum 21. In addition, air is blown from an air blowing unit 24 onto the sheet S as it is transported, accelerating the drying of the ink on the sheet S.

A humidifying device 30 that applies water, which is a humidifying liquid (second liquid), to the sheet S is arranged in the humidifying section 4 . The humidifying device 30 has a nozzle 31 as a liquid ejecting means for ejecting water onto the sheet S. In addition to water, the humidifying liquid may also be transparent ink (solvent) that does not contain a coloring material.

The sheet recovery section 5 is provided with a transport roller 15 that transports the sheet S and a recovery roller 16 that winds up and recovers the sheet S. The sheet S that has passed through the drying section 3 is transported to the recovery roller 16 by the transport roller 15, and the sheet S is wound up into a roll by the rotating recovery roller 16 and recovered.

The control unit 6 is composed of an information processing device such as a PC (Personal Computer). In addition to generating image data to be formed on the sheet S, the control unit 6 controls various operations of the sheet supply unit 1, image forming unit 2, drying unit 3, humidification unit 4, and sheet recovery unit 5. For example, the control unit 6 controls the rotation speed of the supply roller 11, the ink discharge operation of the liquid discharge heads 13Y, 13M, 13C, and 13K, the temperature of the heating drum 21 and heating roller 22, the air blowing operation of the air blowing unit 24, the discharge operation of the nozzle 31, the rotation speed of the recovery roller 16, etc.

FIG. 3 is a diagram showing the configuration of the drying device according to this embodiment.

As shown in FIG. 3, the drying device 20 according to this embodiment includes one heating drum 21, multiple heating rollers 22, multiple guide rollers 23, and multiple air blowing units 24.

The heating drum 21 is a large diameter roller (cylindrical member) that has a heat source inside. On the other hand, the heating roller 22 is a roller (cylindrical member) having a smaller diameter than the heating drum 21, and like the heating drum 21, a heat source is arranged inside. The guide roller 23 is a roller that, unlike the heating drum 21 and the heating roller 22, does not have a heat source such as a heater inside, and functions as a guide means for guiding the sheet S.

A number of heating rollers 22 and a number of guide rollers 23 are arranged in a spiral shape around the heating drum 21. The sheet S is stretched over each of the guide rollers 23, as well as each of the heating rollers 22 and the heating drum 21, which together form a guide path for guiding the sheet S.

When the sheet S is conveyed into the drying device 20, the sheet S is hung on the outside of the heating roller 22. In addition, the "outside of the heating roller 22" here means the opposite side of the center side when the center side of the heating drum 21 is the inside. When the sheet S is hung on the outside of the heating roller 22, the sheet S contacts the heating roller 22 on the non-image forming surface opposite to the image forming surface (ink-attached surface). Therefore, the sheet S is heated from the non-image forming surface side. Then, the sheet S is transported while contacting the multiple heating rollers 22, and then wrapped around the heating drum 21. Furthermore, the sheet S is hung from the heating drum 21 to the guide roller 23, and the non-image forming surface of the sheet S is transported while contacting the inside of the multiple heating rollers 22. In this way, the sheet S is transported while contacting the outside of the heating roller 22, then wrapped around the heating drum 21, and further transported while contacting the inside of the heating roller 22, so that the sheet S is efficiently heated and the drying of the ink on the sheet S is promoted.

Further, air is blown onto the sheet S from the air blowing unit 24 at a location where the sheet S is stretched by the heating roller 22 and the guide roller 23 and at a location facing the heating drum 21 . This further accelerates the drying of the ink. Thereafter, the sheet S is carried out of the drying device 20.

By the way, when a sheet to which ink adheres is dried using a drying device as in this embodiment, not only the ink on the sheet dries, but also the water contained in the sheet evaporates. rate decreases. When the sheet is left with its moisture content reduced, the sheet absorbs surrounding moisture, and the absorbed moisture causes the sheet to expand and stretch. However, at this time, if there is a difference in the amount of elongation of the sheet, a waving phenomenon called cockling occurs in the sheet. For example, when multiple sheets are left on top of each other, the edges of the sheets tend to absorb moisture, while the center of the sheet absorbs less moisture than the edges. The ends are more elongated than the center, and the difference in the amount of elongation between the ends and the center causes a waving phenomenon.

Therefore, in the image forming apparatus according to this embodiment, a humidifying device is provided to suppress waviness of the sheet. By replenishing moisture to the sheet using the humidifying device, the moisture content of the sheet, which has been reduced by the drying process using the drying device, can be increased, suppressing moisture absorption when the sheet is left thereafter and suppressing waviness caused by differences in the amount of water absorbed at the edges and center.

Specifically, in this embodiment, a so-called two-fluid spray type device is used as a humidifying device that applies humidifying water to a sheet, which discharges a humidifying liquid together with compressed gas from a discharge port. . Hereinafter, the configuration of the humidifying device according to this embodiment will be explained based on FIG. 4.

As shown in FIG. 4, the humidifier 30 includes a two-fluid spray nozzle 31, an air compressor 32, a pressurized tank 33, a gas flow path 34, a liquid flow path 35, a gas valve 36, a liquid valve 37, a gas pressure regulator 38, a liquid pressure regulator 39, and a control unit 6.

The nozzle 31 is a liquid ejection means that ejects liquid onto the sheet S. The nozzle 31 is provided with a discharge port 31a that discharges a humidifying liquid together with the supplied gas.

The air compressor 32 is a gas supply source that supplies gas to the nozzle 31 and the pressurized tank 33. In this embodiment, air is used as an example of gas. The air compressor 32 and the nozzle 31 and the air compressor 32 and the pressurized tank 33 are connected by a gas flow path 34. The thick solid line arrows in FIG. 4 indicate the supply route and supply direction through which gas (compressed air) is supplied from the air compressor 32 to the nozzle 31 and the pressurized tank 33 via the gas flow path 34. Further, in addition to the air compressor 32, a blower or the like may be used as the gas supply source.

The pressurized tank 33 is a liquid storage section that stores liquid to be supplied to the nozzle 31. In this embodiment, water, which is a humidifying liquid, is stored in the pressurized tank 33. The pressurized tank 33 and the nozzle 31 are connected by a liquid flow path 35. Further, the pressurized tank 33 is also connected to the air compressor 32 via the gas flow path 34, so that when gas is supplied from the air compressor 32 to the pressurized tank 33, it is stored in the pressurized tank 33. Liquid (water) is pressurized. As a result, the liquid (water) in the pressurized tank 33 is pushed out and supplied to the nozzle 31 via the liquid flow path 35. The thick dotted arrows in FIG. 4 indicate the supply route and supply direction of the liquid (water) supplied from the pressurized tank 33. That is, in this embodiment, the pressurized tank 33 that stores liquid and the air compressor 32 that pushes out the liquid in the pressurized tank 33 function as a liquid supply source that supplies liquid to the nozzle 31. Further, a pressurized water supply pump or the like may be used as the liquid supply source.

The gas valve 36 is a means for starting and stopping the supply of gas to the nozzle 31 under the control of the control unit 6, and is provided in the gas flow path 34 that connects the air compressor 32 and the nozzle 31.

On the other hand, the liquid valve 37 is a means for starting and stopping the supply of liquid to the nozzle 31 under the control of the control unit 6, and is provided in the liquid flow path 35 that connects the pressurized tank 33 and the nozzle 31. .

The gas pressure regulator 38 is a gas pressure adjustment means that adjusts the gas pressure of the gas (compressed air) supplied to the nozzle 31 under the control of the control unit 6. The gas pressure regulator 38 is provided in the gas flow path 34 between the air compressor 32 and the nozzle 31, upstream of the gas valve 36 in the gas supply direction.

The liquid pressure regulator 39 is a liquid pressure adjusting means that adjusts the liquid pressure of the liquid supplied to the nozzle 31 under the control of the control unit 6. The liquid pressure regulator 39 is provided in the gas flow path 34 that connects the air compressor 32 and the pressurized tank 33. The liquid pressure regulator 39 adjusts the gas pressure of the gas (compressed air) supplied to the pressurized tank 33 under the control of the control unit 6, so that the pressurizing force applied to the liquid in the pressurized tank 33 changes. , the force with which the liquid is pushed out from the pressurized tank 33, that is, the liquid pressure of the liquid supplied to the nozzle 31, is adjusted.

The control unit 6 is an information processing device such as a PC (Personal Computer) that controls the operation of the entire image forming apparatus. In this embodiment, the humidifier 30 and various other devices are controlled by a common control unit 6, but these devices may also be controlled by separate control units.

Next, the operation of the humidifying device according to this embodiment will be explained.

First, when the air compressor 32 is driven with both the gas valve 36 and the liquid valve 37 closed, gas (air) is supplied into the gas flow path 34. The gas supplied into the gas flow path 34 is adjusted to a predetermined pressure by the gas pressure regulator 38 and the liquid pressure regulator 39. The pressure-adjusted gas is then supplied to the pressurized tank 33, and the liquid in the pressurized tank 33 is pressurized.

When the gas valve 36 and the liquid valve 37 are opened from this state, compressed gas (compressed air) is supplied from the air compressor 32 to the nozzle 31, and humidification liquid (water) is supplied from the pressure tank 33 to the nozzle 31. The compressed gas and humidification liquid are then ejected together from the ejection port 31a of the nozzle 31, and the liquid is applied to the sheet S.

Here, the amount of liquid discharged from the discharge port 31a of the nozzle 31 is adjusted by adjusting the gas pressure of the compressed gas supplied to the nozzle 31 or by adjusting the liquid pressure of the liquid supplied to the nozzle 31. be able to. That is, the amount of liquid discharged can be adjusted by adjusting the pressure by the gas pressure regulator 38 or by adjusting the pressure by the liquid pressure regulator 39. However, adjusting either the gas pressure or the liquid pressure changes not only the amount of liquid discharged but also the spray pattern of the liquid, which causes variations in the amount of liquid applied to the sheet.

Figure 5 is a graph showing the relationship between gas pressure, liquid pressure, and the variation in the amount of liquid dispensed when the liquid pressure is changed while the gas pressure is kept constant in a two-fluid spray type liquid discharge means.

In FIG. 5, A, B, and C show the variation in the amount of liquid dispensed when the liquid pressure is changed while maintaining different gas pressures, and the magnitude relationship between the gas pressures of A, B, and C is A<B<C. As shown in FIG. 5, in any of the cases of A, B, and C, if the liquid pressure is increased while maintaining a constant gas pressure, the variation in the amount of liquid dispensed gradually increases. The variation in the amount of liquid dispensed also differs depending on the gas pressure. That is, even if the liquid pressure (P0) is the same in A, B, and C, the variation in the amount of liquid dispensed increases as the gas pressure decreases (B more than C, and A more than B). Thus, in a two-fluid spray type liquid discharge means, if only one of the gas pressure or liquid pressure is adjusted, variation in the amount of liquid dispensed occurs. If the amount of humidifying liquid applied to the sheet varies as a result of adjusting only either the gas pressure or the liquid pressure, the content of the humidifying liquid in the sheet will also vary. If the sheet is then left alone, the uneven liquid content will cause unevenness in the amount of stretch in the sheet. As a result, it may not be possible to effectively suppress waving in the sheet, or the waving may become more pronounced.

As described above, the two-fluid spray type liquid ejection means has a problem in that the amount of humidifying liquid applied to the sheet varies. Therefore, in the humidifying device according to the present embodiment, in order to suppress variations in the amount of humidifying liquid applied to the sheet, the amount of liquid discharged is changed in the following manner.

According to the relationship between the gas pressure, the liquid pressure, and the variation in the amount of liquid applied shown in FIG. 5, if the liquid pressure is increased while maintaining a constant gas pressure, the variation in the amount of liquid applied increases. On the other hand, if the liquid pressure is the same (for example, P0), the variation in the amount of liquid applied decreases as the gas pressure increases (B is greater than A, and C is greater than B). In this way, if the liquid pressure is the same, the variation in the amount of liquid applied tends to decrease as the gas pressure increases. Therefore, focusing on this relationship, in the humidifier according to this embodiment, when increasing the amount of liquid discharged from the discharge port 31a, the gas pressure is increased in conjunction with the increase in the liquid pressure. This makes it possible to reduce the increase in the variation in the amount of liquid applied that accompanies an increase in the liquid pressure by increasing the gas pressure. In other words, if the liquid pressure is increased by the liquid pressure regulator 39, the gas pressure can be increased by the gas pressure regulator 38 to suppress the variation in the amount of humidifying liquid applied to the sheet.

As described above, in the humidifying device according to the present embodiment, when changing the amount of humidifying liquid discharged from the discharge port 31a, the amount of humidifying liquid applied to the sheet is adjusted by adjusting both the gas pressure and the liquid pressure. Since variations in the applied amount can be suppressed, it is possible to suppress unevenness in the content of the humidifying liquid contained in the sheet. As a result, it is possible to suppress the occurrence of unevenness in the amount of sheet elongation when the sheet is left unused, and therefore it is also possible to suppress the waving of the sheet.

It is preferable to adjust the gas pressure and liquid pressure at the same time when changing the amount of humidifying liquid to be discharged. However, the gas pressure and the liquid pressure are not necessarily adjusted at the same time, but may be adjusted at different timings.

FIGS. 6 and 7 show an example of the nozzle included in the humidifying device according to the present embodiment and its spray range.

As shown in FIG. 6, in this example, the liquid is ejected from the nozzle 31 in a spreading manner, and as shown in FIG. 7, the liquid ejection range (spray range) E is an ellipse centered on the position of the ejection port 31a of the nozzle 31. Therefore, in this example, the application range of the humidification liquid applied to the sheet from the nozzle 31 is also an ellipse when viewed from a direction perpendicular to the sheet.

Furthermore, as shown in FIG. 8, in this example, there are variations in the amount of liquid ejected from the nozzles. Specifically, assuming that the major axis direction of the elliptical liquid discharge range E shown in FIG. 7 is the X direction, the amount of liquid discharged from the nozzle 31 is equal to It will be less at both ends. That is, the amount of liquid ejected is greatest at a position facing the ejection port 31a of the nozzle 31, and gradually decreases as the distance from the ejection port 31a increases.

As described above, in the case of the nozzle 31 shown in FIGS. 6 and 7, the amount of liquid ejected varies, so when such a nozzle 31 is used as a liquid ejecting means, the amount of humidifying liquid applied to the sheet also varies. There is a possibility that variations may occur. Therefore, in this embodiment, the nozzles 31 are arranged as follows.

Figures 9 and 10 show an example of the nozzle arrangement according to this embodiment.

9 and 10, in this example, nozzles 31 are arranged on each of the front side 200 and the back side 300 of the sheet S, so that the humidifying liquid is applied to both the front side 200 and the back side 300 of the sheet S. As shown in FIG. 10, when viewed from a direction perpendicular to the sheet S, the multiple nozzles 31 are arranged at equal intervals across the width direction (horizontal direction in FIG. 10) intersecting the sheet conveying direction Y, and further, the long axis direction X of the liquid application ranges E1 and E2 ejected from each nozzle 31 is arranged so as to be oblique to the sheet conveying direction Y. Also, as shown in FIG. 10, the range E1 where the humidifying liquid is applied to the sheet S from the front side and the range E2 where the humidifying liquid is applied to the sheet S from the back side are arranged so as to overlap each other in the parts other than the parts facing each ejection port 31a (both ends of the liquid application ranges E1 and E2) when viewed from a direction perpendicular to the sheet S. That is, the areas E1 where the humidifying liquid is applied to the front surface of the sheet S and the areas E2 where the humidifying liquid is applied to the back surface of the sheet S are arranged so that the areas where the amount of liquid discharged is relatively small (the areas on both ends of the liquid application areas E1 and E2) overlap each other.

In this way, in this embodiment, the parts where the amount of liquid to be ejected is relatively small (the parts on both end sides of the liquid application ranges E1 and E2) are arranged so as to overlap with each other, so that the insufficient amount of liquid to be applied can be avoided. It can be supplemented. On the other hand, the portions where a relatively large amount of liquid is applied (the portions facing the ejection port 31a) are arranged so as not to overlap with each other, thereby avoiding an excessive increase in the amount of liquid applied. As a result, in this embodiment, it is possible to suppress variations in the amount of humidifying liquid applied to the sheet S, and it is possible to effectively suppress the occurrence of waviness of the sheet S.

In the example shown in FIG. 9, the nozzle 31 on the front side 200 and the nozzle 31 on the back side 300 are arranged at the same position in the sheet conveyance direction Y, but as in the example shown in FIG. The nozzles 31 on the back side 300 and the nozzles 31 on the back side 300 may be arranged at positions shifted from each other in the sheet conveyance direction Y. In that case, as shown in FIG. 12, the parts on the front side and the back side where the amount of liquid ejected is relatively small (the parts on both end sides of the liquid application ranges E1 and E2) are arranged so as to overlap each other, so that the amount of liquid applied is By arranging the relatively large portions (the portions facing the discharge ports 31a) so as not to overlap each other, variations in the amount of humidifying liquid applied to the sheet S can be suppressed. In short, as shown in FIG. 12, when viewed from the direction perpendicular to the sheet S, parts with a small amount of liquid ejected (parts on both end sides of the liquid application ranges E1 and E2) overlap in the sheet conveying direction Y, and the liquid It is sufficient that the portions with a large amount of ejection (portions facing the ejection port 31a) are arranged so as not to overlap each other in the sheet conveyance direction Y.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the gist of the invention.

In the above embodiment, the case where the humidifying liquid is applied to both the front side and the back side of the sheet has been described as an example. The humidifying liquid is not limited to being applied to only one of the front and back surfaces of the sheet.

Further, the humidifying device according to the present invention is not limited to being applied to an image forming apparatus equipped with a drying device (heating device) having heating members such as a heating drum and a heating roller as described above. The present invention is also applicable to an image forming apparatus equipped with a drying device that dries the sheet by blowing air or cold air (without heating the sheet).

The drying device may also be equipped with a drying device of a different type upstream or downstream of the heating roller in the sheet conveying direction, and may dry the sheet using a plurality of drying methods. Examples of the different methods include a non-contact drying device, a heating means (infrared irradiation device or ultraviolet irradiation device) that dries the droplets by applying light energy, and a drying means (blower) that uses air blowing. The non-contact drying means dries the applied surface of the liquid or the back side of the applied surface. By installing the humidifying device according to the present invention in an image forming apparatus equipped with these drying devices of a different type, it is possible to suppress the variation in the amount of humidifying liquid applied to the sheet and to suppress the occurrence of waviness in the sheet.

Further, the humidifying device according to the present invention can also be applied to an image forming apparatus that does not include a drying device. That is, the humidifying device according to the present invention is not limited to applying a humidifying liquid to a sheet after a drying process, but can be used not only when applying a humidifying liquid to a sheet after a drying process, but also when applying a humidifying liquid to an ink-applying part and a non-ink-applying part as described in Patent Document 1 (Japanese Patent No. 6149563). In order to suppress the waving caused by the difference in expansion of the paper in the ink application section, the present invention can also be applied to the case where a humidifying liquid is applied to a non-ink application section.

Further, the humidifying device according to the present invention is not limited to an inkjet image forming apparatus, but may be installed in an electrophotographic image forming apparatus that forms images using toner.

Note that an inkjet type image forming apparatus is also an example of a liquid ejecting apparatus to which the present invention is applied. The term "liquid ejecting device" refers to a device that includes a liquid ejecting section and drives the liquid ejecting section to eject liquid onto a sheet.

Furthermore, the "liquid ejecting device" to which the present invention is applied includes means for feeding, transporting, and discharging sheets, as well as pre-processing devices, post-processing devices, and the like.

Furthermore, the "liquid ejecting device" may be one in which the liquid ejecting section moves relative to the sheet, or may be one in which the liquid ejecting section does not move relative to the sheet. As a specific example, the "liquid ejection apparatus" includes a serial type apparatus that moves a liquid ejection head (liquid ejection part), a line type apparatus that does not move a liquid ejection head (liquid ejection part), and the like.

Furthermore, a "liquid ejection device" is not limited to a device that uses ejected liquid to visualize meaningful images such as letters and figures. For example, a "liquid ejection device" also includes a device that forms patterns that have no meaning in themselves, and a device that creates three-dimensional images.

Further, the "liquid ejecting device" may be one that ejects a liquid other than ink onto the sheet, such as a treatment liquid applied to the surface of the sheet for the purpose of modifying the surface of the sheet. Therefore, the present invention provides a liquid ejecting unit that includes a liquid ejecting section that ejects a first liquid such as ink onto a sheet, and a humidifying device that applies a humidifying liquid that is a second liquid different from the first liquid to the sheet. Applicable to the device. The "first liquid" is not particularly limited as long as it has a viscosity or surface tension that allows it to be discharged from the liquid discharge part, but the viscosity is 30 mPa・s or less at room temperature, under normal pressure, or by heating or cooling. It is preferable that More specifically, solvents such as water and organic solvents, coloring agents such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , natural dyes and other edible materials, and solutions, suspensions, and emulsions. These can be used, for example, as inkjet inks, surface treatment liquids, constituent elements of electronic devices and light emitting devices, liquids for forming electronic circuit resist patterns, material liquids for three-dimensional modeling, and the like.

Further, the above-mentioned "sheet" is a material to which a liquid can adhere at least temporarily, and includes a material to which a liquid adheres and sticks, a material to which a liquid adheres and permeates, and the like. Specific examples include recording media such as paper, recording paper, film, and cloth, and electronic boards.

The material of the "sheet" can be anything to which the liquid can adhere, even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, or ceramics.

In summary, the aspects of the present invention described above include a humidifier, an image forming apparatus, and a liquid ejection apparatus that have at least the following configurations:

[First Configuration]
The first configuration is a humidifier that ejects humidifying liquid together with gas from an outlet to apply the humidifying liquid to a sheet, and is equipped with a gas pressure adjustment means for adjusting the gas pressure of the gas ejected from the outlet, and a liquid pressure adjustment means for adjusting the liquid pressure of the humidifying liquid supplied to the outlet, and when changing the amount of the humidifying liquid ejected from the outlet, the humidifier adjusts both the gas pressure of the gas and the liquid pressure of the humidifying liquid.

[Second Configuration]
A second configuration is a humidifier configured as described above in the first configuration, which adjusts both the gas pressure of the gas and the liquid pressure of the humidifying liquid simultaneously.

[Third configuration]
A third configuration is a humidifying device in which, in the first or second configuration, the humidifying liquid is applied within an elliptical range centered on the discharge port.

[Fourth configuration]
In a fourth configuration, in any one of the first to third configurations, the discharge port is arranged to discharge the humidifying liquid to each of the front surface and the back surface of the sheet, The ejection ports that eject the humidifying liquid onto the front surface of the sheet and the ejection ports that eject the humidifying liquid onto the back surface of the sheet are equidistant to each other when viewed from a direction perpendicular to the sheet. This is a humidifier placed at intervals.

[Fifth Configuration]
A fifth configuration is a humidifier device in which, in any one of the first to third configurations, the outlet is arranged to eject the humidifying liquid onto each of the front and back surfaces of the sheet, and the range in which the humidifying liquid is applied from the outlet to the front surface of the sheet and the range in which the humidifying liquid is applied from the outlet to the back surface of the sheet are arranged so as to overlap each other when viewed from a direction perpendicular to the sheet, except for the portion facing the outlet.

[Sixth Configuration]
The sixth configuration is an image forming apparatus including an image forming section that forms an image on a sheet, and a humidifier having any one of the first to fifth configurations that applies a humidifying liquid to the sheet.

[Seventh Configuration]
The seventh configuration is a liquid ejection device including a liquid ejection section that ejects a first liquid onto a sheet, and a humidification device of any one of the first to fifth configurations that applies a second liquid, which is a humidification liquid, to the sheet.

[Eighth Configuration]
The eighth configuration is a liquid ejection device according to the seventh configuration, further comprising a drying section for drying the sheet onto which the first liquid has been ejected, and the humidifying device is a liquid ejection device that applies a humidifying liquid to the sheet after the drying process by the drying section.

REFERENCE SIGNS LIST 1 Sheet supply section 2 Image forming section 3 Drying section 4 Humidifying section 5 Sheet recovery section 13Y, 13M, 13C, 13K Liquid ejection head (liquid ejection section)
30 Humidifier 31 Nozzle 31a Discharge port 32 Air compressor 33 Pressurized tank 38 Gas pressure regulator (gas pressure adjustment means)
39 Liquid pressure regulator (liquid pressure adjustment means)
100 Image forming apparatus S Sheet

Patent No. 6149563

Claims (8)

A humidifying device that discharges a humidifying liquid together with gas from a discharge port to apply the humidifying liquid to a sheet,
a gas pressure adjusting means for adjusting the gas pressure of the gas discharged from the discharge port;
a liquid pressure adjusting means for adjusting the liquid pressure of the humidifying liquid supplied to the discharge port,
A humidifying device characterized in that when changing the amount of the humidifying liquid discharged from the discharge port, both the gas pressure of the gas and the liquid pressure of the humidifying liquid are adjusted. The humidifier of claim 1, which simultaneously adjusts both the gas pressure of the gas and the liquid pressure of the humidifying liquid. The humidifying device according to claim 1 or 2, wherein the humidifying liquid is applied within an elliptical area centered on the discharge port. The discharge port is arranged to discharge the humidifying liquid to each of the front surface and back surface of the sheet,
The ejection ports that eject the humidifying liquid onto the front surface of the sheet and the ejection ports that eject the humidifying liquid onto the back surface of the sheet are equidistant to each other when viewed from a direction perpendicular to the sheet. The humidifier according to claim 1 or 2, which is arranged at intervals. the discharge ports are arranged to discharge the moistening liquid onto each of the front and back surfaces of the sheet,
The humidifier device of claim 1 or 2, wherein the area where the humidifying liquid is applied from the outlet to the front surface of the sheet and the area where the humidifying liquid is applied from the outlet to the back surface of the sheet are arranged so as to overlap each other in areas other than the area facing the outlet when viewed from a direction perpendicular to the sheet. An image forming apparatus comprising: an image forming section that forms an image on a sheet; and a humidifying device according to claim 2 that applies a humidifying liquid to the sheet. A liquid ejection device comprising a liquid ejection unit that ejects a first liquid onto a sheet, and a humidification device according to claim 1 or 2 that applies a second liquid, i.e., a humidification liquid, onto the sheet. comprising a drying section that dries the sheet onto which the first liquid has been discharged;
The liquid ejecting device according to claim 7, wherein the humidifying device applies a humidifying liquid to the sheet after the drying process by the drying section.

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