JP2016052791A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent coagulation of liquid discharged to a base layer having poor wettability.SOLUTION: A printer comprises: a print head discharging liquid; and a control section causing first liquid to be discharged from the print head, forming a coagulation prevention protrusion portion on a medium and causing second liquid to be discharged from the print head onto a region including the coagulation prevention protrusion portion. Coagulation of transparent ink can be prevented by forming the coagulation prevention protrusion portion and uniform glossiness can be obtained even in a plastic film or the like having a base layer having poor wettability against the ink.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a printing apparatus.

2. Description of the Related Art Conventionally, there has been known a technique for improving image quality by irradiating ultraviolet rays and then curing the ink in a short time by discharging ultraviolet curable ink onto a medium having low wettability such as a plastic film. In addition, a technique for improving the visibility of an image by forming an image with an ultraviolet curable color ink and then coating with a transparent ink is known. In addition, a technique is known in which an image is formed with color ink after a white ink is ejected onto a medium such as a transparent plastic film to form an undercoat layer as a background.

JP 2010-195002 A

However, in a region where the coverage with the ultraviolet curable color ink is low, there is a problem that the gloss is uneven due to aggregation of the transparent ink on a medium with low wettability. In addition, when coating with a transparent ink is performed except for an area where the coverage with the UV curable color ink is low, there is a problem that a difference in gloss occurs between the area where the medium is exposed and the area where the medium is coated. Further, when the wettability of the undercoat layer made of white ink is weak, there is a problem that the image quality deteriorates due to aggregation of the color ink.

The present invention has been created to solve these problems, and an object of the present invention is to prevent aggregation of liquid discharged on a base layer having low wettability.

(1) A printing apparatus for achieving the above object includes a print head that discharges liquid, and discharges a first liquid from the print head to form an aggregation preventing protrusion on the medium. And a controller that discharges the second liquid from the print head in a region that includes the second liquid.

According to the present invention, since the aggregation preventing protrusion is formed on the medium by the first liquid, the aggregation of the second liquid is less likely to occur. Here, the agglomeration prevention protrusion is a protrusion that produces a certain level difference on the surface of the base layer with the effect of preventing the aggregation of the second liquid, and the effect of preventing the aggregation of the second liquid with a certain level of difference in height. It is the protrusion which consists of a 2nd liquid hardened to such an extent that it forms on the surface of a base layer.
Further, “on the medium” means both “without an intermediate on the medium” and “with an intermediate on the medium”.

(2) In the printing apparatus for achieving the above object, the control unit may decrease the discharge amount of the first liquid per region of interest as the wettability between the medium and the first liquid increases.
Since the coverage with the first liquid is affected by the wettability of the medium, the coverage with the first liquid can be accurately adjusted by adopting this configuration.

(3) In the printing apparatus for achieving the above object, the liquid is a photocurable ink, and further includes an irradiation unit that irradiates light to the photocurable ink attached to the medium, and the control unit includes: Before the second liquid is ejected from the print head, light is emitted from the irradiation unit to incompletely cure the first liquid, and after the second liquid is ejected from the print head, from the irradiation unit The first liquid and the second liquid may be completely cured by irradiating light.
By adopting this configuration, the ink can be fixed to the medium without using a volatile organic compound, and the ink can be fixed to a non-absorbing medium such as plastic.

(4) In printing to achieve the above object, the first liquid and the second liquid are transparent inks, and the control unit ejects opaque ink from the print head to form an image on a medium. And adjusting the discharge amount of the first liquid for each region of interest according to the discharge amount of each region of interest of the opaque ink from the print head to the region where the opaque ink and the first liquid are discharged. The second liquid may be discharged.
By forming the anti-agglomeration protrusion with transparent ink, uniform gloss can be obtained without changing the image or degrading the image quality. Further, since the discharge amount of the transparent ink for forming the anti-aggregation protrusion is adjusted according to the discharge amount of the opaque ink, the aggregation with the transparent ink can be prevented even in the region where the coverage with the opaque ink is low.

(5) In the printing apparatus for achieving the above object, the control unit may cause the first liquid to be ejected from the print head only in a region where the ejection amount of the opaque ink is less than a predetermined value.
By adopting this configuration, it is possible to reduce the discharge amount of the transparent ink for forming the anti-aggregation protrusion, and therefore it is possible to suppress yellowing that occurs as aged deterioration.

(6) In the printing apparatus for achieving the above object, the second liquid is an opaque ink, and the control unit causes the third liquid to be ejected from the print head before ejecting the first liquid. Then, an undercoat layer having higher wettability to the second liquid than the medium may be formed on the medium, and the second liquid may be ejected from the print head to form an image on the medium.
By adopting this configuration, the anti-coagulation effect can be enhanced by the undercoat layer in addition to the anti-coagulation protrusion.

1A, 1B, and 1C are plan views according to a first embodiment of the present invention. 2A and 2B are cross-sectional views according to the first embodiment of the present invention. 3A to 3E are cross-sectional views according to the first embodiment of the present invention. The top view concerning the 2nd example of the present invention. 5A, 5B and 5C are plan views according to a third embodiment of the present invention. 6A, 6B and 6C are sectional views according to a third embodiment, a fourth embodiment and a fifth embodiment of the present invention. FIG. 7 is a plan view according to a fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in the following order with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.
1. First Embodiment FIG. 1A shows a main part of a printer 1 as a first embodiment of the present invention. The printer 1 is a serial ink jet printer that discharges ultraviolet curable opaque ink and ultraviolet curable transparent ink from the print head 13 and discharges ultraviolet curable transparent ink from the print head 16. Since the printer 1 ejects ultraviolet curable ink, it can form an image on a print medium with low absorbency such as a plastic film. In addition to the print heads 13 and 16, the printer 1 includes conveyance rollers 11a, 11b, 11c, and 11d, lamps 12a, 12b, and 12d as irradiation units, motors 17a, 17b, and 17c, a control unit 18, and the like.

The transport rollers 11a, 11b, 11c, and 11d are driven and rotated by the motor 17a to transport the print medium in the sub-scanning direction.

Four print heads 13 and two lamps 12 a are fixed to the first carriage 14. The first carriage 14 is fixed to an endless belt 19a. The endless belt 19a is stretched over a pulley 19b driven by a motor 17b. When the endless belt 19a rotates together with the motor 17b, the first carriage 14 moves in the main scanning direction.

As shown in FIG. 1B, each print head 13 includes nozzle rows 13c, 13m, 13y, and 13k that are composed of a number of nozzles that eject opaque ink, and nozzles that are composed of a number of nozzles that eject a first transparent ink. A row 13t is formed. Nozzle rows 13c, 13m, 13y, 13k, and 13t are formed by expanding and contracting a piezo (not shown) provided for each nozzle.
Ink is ejected from each nozzle. Cyan ink is supplied to the nozzle row 13c from an ink cartridge (not shown). Magenta ink is supplied from an ink cartridge (not shown) to the nozzle row 13m. Yellow ink is supplied to the nozzle row 13y from an ink cartridge (not shown). Black ink is supplied to the nozzle row 13k from an ink cartridge (not shown). A colorless and transparent ink is supplied to the nozzle row 13t from an ink cartridge (not shown).

The lamp 12a uses an LED that emits ultraviolet rays as a light source. The lamp 12a incompletely cures the opaque ink and the transparent ink by irradiating the opaque ink and the transparent ink attached to the print medium with weak ultraviolet rays. That is, so-called pinning is performed by the lamp 12a.

The lamp 12 b is located on the downstream side of the first carriage 14. The lamp 12b incompletely cures the opaque ink and the transparent ink by irradiating the opaque ink and the transparent ink attached to the print medium with weak ultraviolet rays.

The second carriage 15 is located on the downstream side (front side in the sub-scanning direction) of the lamp 12b. The second carriage 15 is fixed to the endless belt 19c. Endless belt 19c is motor 1
It is stretched over a pulley 19d driven by 7c. When the endless belt 19c rotates together with the motor 17c, the second carriage 15 moves in the main scanning direction.

Four print heads 16 are fixed to the second carriage 15. As shown in FIG. 1C, each print head 16 is formed with a nozzle row 16t composed of a number of nozzles that eject the second transparent ink. A colorless and transparent ink is supplied to the nozzle row 16t from an ink cartridge (not shown). Ink is ejected from each nozzle of the nozzle row 16t by expanding and contracting a piezo (not shown) provided for each nozzle.

The lamp 12 d is located on the downstream side of the second carriage 15. The lamp 12d completely cures the opaque ink and the transparent ink by irradiating the opaque ink and the transparent ink attached to the print medium with strong ultraviolet rays.

The control unit 18 includes print heads 13 and 16, a motor 17a,
17b, 17c and lamps 12a, 12b, 12d. The control unit 18
A computer including a processor, a RAM, a ROM, an input / output mechanism, and the like (not shown).
The control unit 18 executes the print control program stored in the ROM, thereby ejecting the opaque ink and the transparent ink from the print head 13 to form an image and an aggregation preventing protrusion on the print medium. Transparent ink is ejected from the print head 16 to an area including the prevention protrusion. In addition, the control unit 18 executes the print control program to irradiate weak ultraviolet rays from the lamps 12a and 12b before discharging the second transparent ink from the print head 16, thereby disabling the opaque ink and the first transparent ink. The ink is completely cured, and after the second transparent ink is ejected from the print head 16, strong ultraviolet light is irradiated from the lamp 12d to completely cure the opaque ink, the first transparent ink, and the second transparent ink.

Hereinafter, the control method of the printer 1 will be described in more detail with reference to FIGS. 1 and 2.
The controller 18 drives the transport rollers 11a, 11b, 11c, and 11d,
The print medium M is conveyed in the sub-scanning direction by a predetermined distance. When the print medium M is stopped, the control unit 18 drives the motor 17b to move the first carriage 14 in the main scanning direction. When the first carriage 14 moves in the main scanning direction, the control unit 18 drives the print head 13 to drive cyan, magenta, yellow, black, colorless and transparent from the nozzle rows 13c, 13m, 13y, 13k, and 13t. The ink droplets are ejected toward the printing medium M and weak ultraviolet rays are emitted from the lamp 12a. As a result, the print medium M is formed by incompletely cured cyan, magenta, yellow and black ink droplets Cl, Cm and Cs.
An image is formed on the printing medium M, and an aggregation preventing protrusion T1 is formed on the print medium M by colorless and transparent ink droplets that are incompletely cured. Since the first transparent ink that forms the aggregation preventing protrusion T1 is ejected simultaneously with the opaque ink droplets Cl, Cm, and Cs that form the image in this way, the printing time can be shortened. The position where the transparent ink adheres to the print medium M (the position based on the position where the opaque ink adheres) does not shift.

As shown in FIG. 2, cyan, magenta, yellow, and black ink droplets ejected from the nozzle rows 13c, 13m, 13y, and 13k are large dots Cl, medium dots Cm, and small dots Cs.
One of them. The colorless and transparent ink droplets ejected from the nozzle row 13t are large dots T1.
Only. The first transparent ink droplet may be composed of medium dots or small dots, or may be composed of droplets of a plurality of sizes. The size of the ink droplet is controlled by the driving waveform of the piezo. Based on the image data indicating the ink density for each pixel, the size and number of cyan, magenta, yellow and black ink droplets ejected per region of interest corresponding to the pixel are determined. That is, the image data here is image data after so-called color separation that defines the discharge amount of opaque ink of each color for each region.

Here, a method for determining the discharge amount of the first transparent ink will be described. As already described, the image data after color separation defines the discharge amount of opaque ink of each color for each region. The discharge amount of the first transparent ink is adjusted according to the discharge amount for each region of opaque ink of each color. That is, let X be the discharge amount of the first transparent ink for the region of interest, and cyan for the region of interest.
When the discharge amounts of magenta, yellow, and black ink are c, m, y, and k, respectively,
X = f (c, m, y, k).

The function f that determines the discharge amount of the first transparent ink for the region of interest is determined according to the characteristics of the colorless transparent ink and the print medium M, the characteristics of the lamps 12a and 12b, and the like. It is determined that at least the discharge amount of the first transparent ink decreases as the discharge amount of the opaque ink increases. For example, it is preferable to define the function f so that the value of X becomes smaller as the wettability between the printing medium M and the colorless and transparent ink is stronger. A specific example of the function f is shown below. X,
The value ranges of c, m, y, and k are all 0 or more and 1 or less. The value “1” means a discharge amount that completely covers the region of interest.

(Example 1)
f = 1 (when c + m + y + k <1)
f = 0 (when c + m + y + k = 1)
In this example, the control unit 18 does not discharge colorless and transparent ink droplets from the nozzle row 13t when the region of interest is completely covered with cyan, magenta, yellow, and black color inks, and cyan, magenta, and yellow. When the region of interest is not completely covered with the black color ink, an amount of colorless and transparent ink droplets that completely cover the region of interest with only the colorless and transparent ink droplets are ejected from the nozzle row 13t. Therefore, in this case, all the attention area is completely covered with the color ink or the colorless and transparent ink.

Even when the region of interest is completely covered with the colorless and transparent ink, as shown in FIG. 3B, before the surface of the ink layer T becomes flat as the colorless and transparent ink droplets flow as shown in FIG. 3A. In addition, by curing the colorless and transparent ink droplet T1, it is possible to form a minute protrusion having a height difference h. This protrusion is an aggregation preventing protrusion that prevents aggregation of the second transparent ink. That is, even when the region of interest is completely covered with the first transparent ink, the aggregation preventing protrusion is formed by curing the colorless and transparent ink droplet T1 before the surface of the ink layer becomes flat. Can do.

(Example 2)
f = 0.5 (when c + m + y + k <0.5)
f = 0 (when c + m + y + k ≧ 0.5)
In the case of this example, the control unit 18 does not discharge colorless and transparent ink droplets from the nozzle row 13t when the region of interest is covered by 50% or more of the color inks of cyan, magenta, yellow, and black. When the target region is covered with less than 50% of yellow, black color ink, colorless and transparent ink droplets of an amount that covers the target region with 50% of the colorless and transparent ink droplets are ejected from the nozzle row 13t. So in this case,
All regions of interest are covered with 50% or more of color ink or colorless and transparent ink. When the function f of Example 2 is used, the fixing amount of the first transparent ink on the print medium can be reduced as compared with the case of using the function of Example 1. As the fixing amount of the first transparent ink on the print medium is reduced, yellowing of the printed matter can be suppressed.

Even when the region of interest is not completely covered with the colorless and transparent ink, the colorless and transparent ink droplet T1 is cured before the colorless and transparent ink droplet flows and the surface of the ink layer becomes flat. As shown in 3C, it is possible to form a minute protrusion having a height difference h. When compared under the same curing conditions, the height difference h of the anti-aggregation protrusion can be increased when the region of interest is not completely covered with the colorless and transparent ink as compared with the case where the region is completely covered. The greater the height difference h of the anti-aggregation protrusion, the higher the effect of preventing the aggregation of the second opaque ink.

(Example 3)
f = 0.3 (when c + m + y + k <0.3)
f = 0 (when c + m + y + k ≧ 0.3)
In the case of this example, the control unit 18 does not discharge colorless and transparent ink droplets from the nozzle row 13t and covers cyan, magenta, and the like when covering the region of interest by 30% or more with cyan, magenta, yellow, and black color inks. When the target region is covered with less than 30% by yellow, black color ink, colorless and transparent ink droplets of an amount that covers the target region by 30% only by the colorless and transparent ink droplets are ejected from the nozzle row 13t. So in this case,
All regions of interest are covered with 30% or more of color ink or colorless and transparent ink. When the function f of Example 3 is used, the fixing amount of the first transparent ink onto the print medium can be reduced as compared with the case of using the functions of Examples 1 and 2.

As shown in FIG. 3D, when the distance d between the ink droplets T1 is larger than the diameter of the second transparent ink, a gap is generated in which the second transparent ink moves on the surface of the print medium M1. On the other hand, the yellowing of the printed matter can be suppressed as the amount of the first transparent ink fixed to the print medium is reduced. Further, when the printing medium M2 having a higher wettability with ink than the printing medium M1 is used, the interval d between the ink droplets T1 is narrowed (the coverage is increased) as shown in FIG. Further, since the ink droplets adhering to the printing medium flow and spread, the longer the period until the ink droplets are cured, the narrower the interval between the ink droplets. From these viewpoints, the interval d between the ink droplets of the first transparent ink is optimized. That is, the discharge amount of the first transparent ink correlated with the interval d between the ink droplets is adjusted by the viscosity of the ink, the wettability between the printing medium and the ink, the ink curing conditions, and the like. Therefore, for example, the control unit 18 preferably changes the discharge amount of the first transparent ink according to the absorption characteristics of the print medium. Therefore, the absorption characteristic of the print medium may be detected using a sensor, the type or the absorption characteristic of the print medium may be set by the user, and the coefficient of the function f that determines the discharge amount of the first transparent ink May be set by the user.

From nozzle rows 13c, 13m, 13y, 13k, 13t, cyan, magenta, yellow,
When black, colorless and transparent ink droplets are being ejected toward the print medium M, the control unit 18 irradiates the print medium M with ultraviolet rays from the lamp 12a. Immediately after adhering to the print medium M, cyan, magenta, yellow, black, and colorless and transparent ink droplets adhering to the print medium M are incompletely cured by the ultraviolet rays irradiated from the lamp 12a. For this reason, the print medium M
Ink droplets are prevented from mixing on the surface. On the other hand, since the ink droplets are not completely cured by the ultraviolet rays irradiated from the lamp 12a, the ink droplets after irradiation do not repel the ink droplets adhering to the surface.

After ejecting cyan, magenta, yellow, black, and colorless and transparent ink droplets corresponding to the image data to an area of a predetermined width of the print medium, the control unit 18 drives the motor 17a to move the print medium M in the sub-scanning direction. Move. The control unit 18 detects cyan, magenta, and the like attached to the print medium M.
When the yellow, black, colorless and transparent ink droplets move to the front of the lamp 12b, the lamp 12
b is turned on, and ultraviolet rays are irradiated toward the print medium M from the lamp 12b. As a result, cyan, magenta, yellow, incompletely cured by ultraviolet rays irradiated from the lamp 12a,
Curing of black and colorless and transparent ink proceeds. Accordingly, it is possible to prevent the cyan, magenta, yellow, and black inks from being mixed with the second transparent ink. Further, cyan, magenta, yellow, black, and colorless and transparent ink can be prevented from being transferred to the transport roller 11c. However, if cyan, magenta, yellow, black, and the first transparent ink are completely cured before the second transparent ink is ejected, the wettability with the second transparent ink becomes remarkably weak, and the second transparent ink It will repel ink. For this reason, the amount of ultraviolet light emitted from the lamp 12b is adjusted to such an extent that cyan, magenta, yellow, black, and the first transparent ink are not completely cured.

When the area of the print medium M to which ink droplets of cyan, magenta, yellow, black, and colorless and transparent are attached moves to the front of the second carriage 15, the control unit 18 stops the motor 17a. Printing medium M with cyan, magenta, yellow, black, colorless and transparent ink droplets attached
When the print medium M is stopped at a position where this area becomes the front surface of the second carriage 15, the control unit 18 drives the motor 17c to move the second carriage 15 in the main scanning direction. When the second carriage 15 is moving in the main scanning direction, the control unit 18 drives the print head 16 to eject colorless and transparent ink droplets from the nozzle row 16 t toward the print medium M. As a result, as shown in FIG. 2B, a layer composed of cyan, magenta, yellow, black, and the first transparent ink is covered with the second transparent ink. At this time, the second transparent ink droplet T2 attached to the surface having a large number of minute aggregation preventing protrusions formed by cyan, magenta, yellow, black, and the first transparent ink is moved by the aggregation preventing protrusions. Does not agglomerate. Further, since the cyan, magenta, yellow, black, and first transparent ink are not completely cured, the movement of the second transparent ink droplet T2 is limited. Therefore, the surface of the layer composed of cyan, magenta, yellow, black, and the first transparent ink can be covered with the second transparent ink having a uniform thickness. Therefore, gloss spots are suppressed.

In the state not covered by the second transparent ink, cyan, magenta, yellow,
As shown in FIG. 2A, minute irregularities exist on the surface of the black, first transparent ink layer. Since the unevenness causes irregular reflection, the visibility of the image is deteriorated. After the irregularities are covered with the second transparent ink, the surface of the second transparent ink is flattened by the flow, so that irregular reflection is suppressed, so that the visibility of the image is improved.

After ejecting the second transparent ink to the area of the predetermined width of the print medium, the control unit 18 moves the motor 17
a is driven to move the print medium M in the sub-scanning direction. The control unit 18 turns on the lamp 12d when cyan, magenta, yellow, black, and colorless and transparent ink adhering to the print medium M moves to the front of the lamp 12d, and irradiates the print medium M with strong ultraviolet rays from the lamp 12d. Let As a result, cyan, magenta, yellow, black, and colorless and transparent ink adhering to the printing medium M are completely cured.

2. Second Embodiment FIG. 4 shows a main part of a printer 2 as a second embodiment of the present invention. The printer 2 discharges ultraviolet curable opaque ink from the print head 23c, and print head 23t,
This is a line-type ink jet printer that discharges ultraviolet curable transparent ink from 23d. In addition to the print heads 23c, 23t, and 23d, the printer 2 includes transport rollers, a motor (not shown), lamps 22c, 22t, and 22d as irradiation units, a control unit 28, and the like.

The print head 23c ejects opaque ink, and four print heads 23c are provided for each of cyan, magenta, yellow, and black inks. Each print head 23c is formed with a nozzle row 231 composed of a number of nozzles that discharge one type of opaque ink. Four print heads 23c that discharge one kind of opaque ink are disposed adjacent to each other in the main scanning direction and two in the sub scanning direction. Four print heads 23 that discharge one kind of opaque ink
By the nozzle row 231 formed in c, it is possible to eject ink droplets at predetermined equal intervals in a predetermined width area on the medium.

Four print heads 23t that discharge the first transparent ink are provided on the downstream side (front side in the sub-scanning direction) of the print head 23c. Each print head 23t is formed with a nozzle row 232 composed of a large number of nozzles that discharge colorless and transparent ink. Two print heads 23t are arranged adjacent to each other in the main scanning direction and two in the sub scanning direction. By the nozzle rows 232 formed on the four print heads 23t, it is possible to discharge the first transparent ink at predetermined equal intervals to a predetermined width area on the medium.

The lamp 22c includes four print heads 23c that discharge one type of opaque ink and four print heads 23c that discharge one other type of opaque ink, and four print heads 23c provided on the most downstream side. One is provided between four print heads 23t that discharge one transparent ink. The lamp 22c uses an LED that emits ultraviolet rays as a light source. Lamp 2
In 2c, the opaque ink is incompletely cured by irradiating the opaque ink attached to the print medium with weak ultraviolet rays. In other words, the pinning is performed on the opaque ink of each color by the lamp 22c.

A lamp 22t is provided on the downstream side of the four print heads 23t that discharge the first transparent ink. The lamp 22t uses an LED that emits ultraviolet rays as a light source. The lamp 22t is
The first transparent ink is incompletely cured by irradiating the first transparent ink attached to the print medium with weak ultraviolet light. That is, the pinning for the first transparent ink is performed by the lamp 22t.

Four print heads 23d that discharge the second transparent ink are provided on the downstream side of the lamp 22t. Each print head 23d is formed with a nozzle row 233 composed of a number of nozzles that discharge colorless and transparent ink. Two print heads 23d are adjacently arranged in the main scanning direction and two in the sub scanning direction. By the nozzle rows 233 formed on the four print heads 23d, it is possible to discharge the first transparent ink at predetermined equal intervals to a predetermined width area on the medium.

A lamp 22d is provided on the downstream side of the print head 23d. The lamp 22d uses an LED that emits ultraviolet rays as a light source. The lamp 22d completely cures the opaque ink and the transparent ink by irradiating the opaque ink and the transparent ink attached to the print medium with strong ultraviolet rays.

The control unit 28 is connected to the print heads 23c, 23t, 23d and the lamps 22c, 22t, 22d via a drive circuit (not shown). The control unit 28 includes a processor (not shown), R
A computer having an AM, a ROM, an input / output mechanism, and the like. The control unit 28 executes the print control program stored in the ROM, thereby ejecting opaque ink from the print head 23c to form an image on the print medium, and ejecting the first transparent ink from the print head 23t. Thus, the aggregation preventing protrusion is formed on the print medium, and the second transparent ink is ejected from the print head 23d to an area including the image and the aggregation preventing protrusion. In addition, the control unit 28 executes the print control program to irradiate weak ultraviolet rays from the lamps 22c and 22t before discharging the second transparent ink from the print head 22d, thereby disabling the opaque ink and the first transparent ink. After completely curing and discharging the second transparent ink from the print head 23d, the ultraviolet light is irradiated from the lamp 22d to completely cure the opaque ink, the first transparent ink, and the second transparent ink.

In this embodiment, the period from when the first transparent ink is ejected to the printing medium until the first transparent ink is irradiated with ultraviolet rays is longer than that of the first embodiment. For this reason, the first transparent ink droplet tends to spread as compared with the first embodiment from the time when it adheres to the printing medium until it hardens. Therefore, the control unit 28 applies a small amount of transparent ink to the print head 23t compared to the first embodiment.
It is preferable to discharge from the nozzle.

3. Third Embodiment FIG. 5 shows the main part of a printer 3 as a third embodiment of the present invention. The printer 3 is a serial type ink jet printer that discharges UV curable white ink from the print head 33 and discharges UV curable color ink and colorless transparent ink from the print head 13. In addition to the print heads 13 and 33, the printer 3 includes transport rollers 11a and 1
1b, 11c, 11d, lamps 12a, 12b, 12d as irradiation units, motor 17a
, 17b, 17c, a control unit 38, and the like.

Four print heads 33 are fixed to the first carriage 14. As shown in FIG. 5B, each print head 33 is formed with a nozzle row 33w composed of a number of nozzles that eject white ink. White ink as a third liquid is ejected from each nozzle of the nozzle row 33w by expanding and contracting a piezo (not shown) provided for each nozzle.
The nozzle row 33w is supplied with ultraviolet curable white ink from an ink cartridge (not shown). The white ink in a semi-cured state that is not completely cured forms an undercoat layer having higher wettability than a plastic film used as a packaging material.

On the second carriage 15, four print heads 13 and two lamps 12c as an irradiation unit are fixed. Each print head 13 includes nozzle rows 13c, 1 as in the first embodiment.
3m, 13y, 13k, and 13t are formed. The nozzle row 13t includes a large number of nozzles that discharge colorless and transparent ink as the first liquid. Nozzle rows 13c, 13m, 13y,
13k is composed of a number of nozzles that discharge color ink as the second liquid. Lamp 1
2c uses LED which radiates | emits an ultraviolet-ray as a light source. The lamp 12c incompletely cures the white ink and the colorless transparent ink by irradiating the white ink and the colorless transparent ink attached to the printing medium with weak ultraviolet rays. That is, so-called pinning is performed by the lamp 12c.

The control unit 38 includes print heads 13 and 33, a motor 17a, and a drive circuit (not shown).
17b, 17c and lamps 12a, 12b, 12d. The control unit 38
A computer including a processor, a RAM, a ROM, an input / output mechanism, and the like (not shown).
The control unit 38 executes the print control program stored in the ROM to discharge the white ink from the print head 33 and then irradiate weak ultraviolet rays from the lamps 12a and 12b to incompletely cure the white ink. An undercoat layer made of white ink is formed on the print medium. Further, the control unit 38 discharges the transparent ink from the print head 13 to the area where the undercoat layer is formed, and forms weakening ultraviolet rays from the lamp 12c to incompletely cure the transparent ink, thereby forming the aggregation preventing protrusion. To do. Further, the control unit 38 discharges the color ink from the print head 13 to the area where the undercoat layer and the aggregation preventing protrusion are formed, and irradiates weak ultraviolet rays from the lamp 12c to incompletely cure the color ink, thereby generating an image. Form. The control unit 38 discharges the color ink from the print head 13 and then irradiates the ultraviolet ray from the lamp 12d to completely cure the white ink, the transparent ink, and the color ink.

Hereinafter, the control method of the printer 3 will be described in more detail with reference to FIGS. 5 and 6.
The controller 38 drives the transport rollers 11a, 11b, 11c, and 11d,
The print medium M is conveyed in the sub-scanning direction by a predetermined distance. When the print medium M is stopped, the control unit 38 drives the motor 17b to move the first carriage 14 in the main scanning direction. When the first carriage 14 is moving in the main scanning direction, the control unit 38 drives the print head 33 to discharge white ink from the nozzle row 33w toward the print medium M and emit weak ultraviolet light from the lamp 12a. Irradiate. As a result, as shown in FIG. 6A, an undercoat layer W1 is formed on the print medium M with the incompletely cured white ink. The undercoat layer W1 formed with white ink improves the visibility of an image formed with color ink.

After the white ink undercoat layer is formed in the predetermined width region of the print medium, the control unit 38 drives the motor 17a to move the print medium M in the sub-scanning direction. The control unit 38
When the undercoat layer W1 formed on the print medium M moves to the front of the lamp 12b, the lamp 12b is turned on, and ultraviolet rays are irradiated from the lamp 12b toward the print medium M. as a result,
Curing of the white ink that has been incompletely cured by the ultraviolet rays irradiated from the lamp 12a proceeds. Thereby, it is possible to prevent the white ink from being mixed with the transparent ink or the color ink. Further, it is possible to prevent the white ink from being transferred to the transport roller 11c. However, if the white ink is completely cured before the transparent ink and the color ink are discharged, the wettability between the undercoat layer W1 and the transparent ink and the color ink becomes extremely weak, and the transparent ink and the color ink are repelled. For this reason, the amount of ultraviolet light irradiated from the lamp 12b is adjusted to such an extent that the white ink is not completely cured.

After the ultraviolet light is irradiated to the white ink from the lamp 12b, the control unit 38 controls the motor 17
a is driven to move the print medium M in the sub-scanning direction. When the area of the print medium M on which the undercoat layer is formed moves to the front surface of the second carriage 15, the control unit 38 stops the motor 17a. The area of the print medium M on which the undercoat layer W1 is formed is the second carriage 15
When the print medium M is stopped at a position that is in front of, the control unit 38 drives the motor 17c to move the second carriage 15 in the main scanning direction. When the second carriage 15 is moving in the main scanning direction, the control unit 38 drives the print head 13 to discharge colorless and transparent ink droplets from the nozzle row 13t toward the print medium M and the lamp 1.
Irradiate weak ultraviolet rays from 2c. As a result, as shown in FIG. 6B, the aggregation preventing protrusion T2 is formed on the print medium M by the incompletely cured colorless and transparent ink.

In a state where the region of the print medium M on which the anti-aggregation protrusion T2 is formed is stopped in front of the second carriage 15, the control unit 38 drives the motor 17c again to move the second carriage 15 in the main scanning direction. Move to. When the second carriage 15 is again moved in the main scanning direction, the control unit 38 drives the print head 13 to thereby form the nozzle rows 13c, 13
m, 13y, and 13k to cyan, magenta, yellow, and black ink drops M
In addition, the lamp 12c is irradiated with weak ultraviolet rays. As a result, an image is formed on the print medium M by ink droplets of cyan, magenta, yellow, and black that are incompletely cured. Cyan, magenta, yellow, and black ink droplets Cl, Cm, and Cs adhering to the printing medium M are not aggregated because their movement is restricted by the aggregation preventing protrusion T2 formed of transparent ink. Therefore, a high-definition image can be formed with color ink. Further, since the undercoat layer W1 of cyan, magenta, yellow, and black ink droplets Cl, Cm, and Cs is formed of white ink, an image with excellent visibility is formed.

The control unit 38 discharges colorless and transparent ink from the print head 13 when the second carriage 15 is moving in the main scanning direction, and the second carriage 15 is moving in the direction opposite to the main scanning direction. Sometimes, ink droplets Cl, Cm, and Cs of cyan, magenta, yellow, and black may be ejected from the print head 13. That is, the aggregation preventing protrusion T2 and the image may be formed in the course of the second carriage 15 reciprocating once. Further, the control unit 38 moves the medium M in the reverse direction of the sub-scanning direction before discharging the color ink from the print head 13, and the lamp 12b.
The curing of the colorless and transparent ink may be promoted by irradiating weak ultraviolet rays.

After the image is formed with the color ink, the control unit 38 drives the motor 17a to move the print medium M in the sub scanning direction. The area of the print medium M on which the image is formed is the lamp 12d
, The control unit 38 turns on the lamp 12d and irradiates the printing medium M with strong ultraviolet rays from the lamp 12d. As a result, white, cyan,
Magenta, yellow, black and colorless and transparent inks are completely cured.

4). Fourth Embodiment The aggregation preventing protrusion T2 shown in FIG. 6B may be formed of white ink. When the aggregation preventing protrusion T2 is formed with white ink using the printer 3, the control unit 38 controls each unit as follows.

First, as in the third embodiment, the control unit 38 forms the white ink undercoat layer W1 in a predetermined width region of the print medium.

Next, the control unit 38 drives the motor 17a to move the print medium M in the direction opposite to the sub-scanning direction. When the area of the print medium M on which the undercoat layer W1 is formed moves to the front surface of the first carriage 14, the control unit 38 stops the motor 17a. When the print medium M is stopped at a position where the area of the print medium M on which the undercoat layer W1 is formed is in front of the first carriage 14, the control unit 38 drives the motor 17c again to drive the first carriage again. 14 is moved in the main scanning direction. When the first carriage 14 is again moved in the main scanning direction, the control unit 38 drives the print head 33 to discharge the white ink from the nozzle row 33w toward the print medium M, and weak UV light from the lamp 12a. Irradiate. As a result, the aggregation preventing protrusion T2 is formed on the print medium M as shown in FIG. 6B by the incompletely cured white ink.

Next, the control unit 38 drives the motor 17a to move the print medium M in the sub scanning direction.
When the aggregation preventing protrusion T2 formed on the print medium M moves to the front of the lamp 12b, the control unit 38 turns on the lamp 12b and irradiates the print medium M with ultraviolet rays from the lamp 12b.
As a result, the aggregation preventing protrusion T that has been incompletely cured by the ultraviolet rays irradiated from the lamp 12a.
Curing of 2 proceeds. However, if the white ink is completely cured before the color ink is ejected, the wettability with the color ink becomes extremely weak, and the color ink is repelled.
For this reason, the amount of ultraviolet light irradiated from the lamp 12b is adjusted to such an extent that the white ink is not completely cured.

Next, the control unit 38 drives the motor 17a to move the print medium M in the sub scanning direction.
When the area of the print medium M in which the undercoat layer W1 and the aggregation preventing protrusion T2 are formed by the white ink moves to the front of the second carriage 15, the control unit 18 stops the motor 17a.

The controller 38 drives the motor 17c to drive the second carriage 15 while the area of the print medium M on which the undercoat layer W1 and the aggregation preventing protrusion T2 are formed is stopped in front of the second carriage 15. Is moved in the main scanning direction. When the second carriage 15 is moving in the main scanning direction, the control unit 38 drives the print head 13 to drive the nozzle row 13c.
, 13m, 13y, and 13k, ink droplets of cyan, magenta, yellow, and black are ejected toward the print medium M, and weak ultraviolet rays are emitted from the lamp 12c. As a result, an image is formed on the print medium M by ink droplets of cyan, magenta, yellow, and black that are incompletely cured. Cyan, magenta, yellow, and black ink droplets Cl, Cm, and Cs adhering to the printing medium M are not aggregated because their movement is restricted by the aggregation preventing protrusion T2 formed of white ink. Therefore, a high-definition image is formed. Further, since the undercoat layer W1 of cyan, magenta, yellow, and black ink droplets Cl, Cm, and Cs is formed of white ink, an image with excellent visibility is formed.

Further, the control unit 38 drives the motor 17a to move the print medium M in the sub scanning direction. The control unit 18 turns on the lamp 12d when the white, cyan, magenta, yellow, and black ink attached to the print medium M moves to the front of the lamp 12d, and irradiates the print medium M with strong ultraviolet rays from the lamp 12d. . As a result, the white, cyan, magenta, yellow, and black inks attached to the print medium M are completely cured.

Thereafter, the control unit 38 drives the motor 17a to move the print medium M in the direction opposite to the sub-scanning direction, and drives the print head 13 to discharge colorless and transparent ink droplets from the nozzle row 13t. A transparent overcoat layer may be formed on the surface. In addition,
Needless to say, when the colorless and transparent ink is not used, it is not necessary to form the nozzle row 13t in the print head 13.

5). Fifth Embodiment FIG. 7 shows the main part of a printer 5 as a fifth embodiment of the present invention. The printer 5 discharges ultraviolet curable color ink from the print head 23c, discharges ultraviolet curable white ink from the print head 53w, and discharges ultraviolet curable colorless transparent ink from the print head 53t. It is a printer. In addition to the print heads 23c, 53w, and 53t, the printer 5 includes transport rollers, a motor (not shown), lamps 22c, 52w, and 52t as an irradiation unit, a control unit 58, and the like.

The print head 53w ejects white ink for forming an undercoat layer, and two are arranged adjacent to each other in the main scanning direction and two in the sub scanning direction. Each print head 53w is formed with a nozzle row 531 composed of a number of nozzles that discharge white ink. By the nozzle rows 531 formed on the four print heads 53w, it is possible to discharge white ink at predetermined equal intervals onto a predetermined width area on the medium.

A lamp 52w is provided on the downstream side of the print head 53w. The lamp 52w uses an LED that emits ultraviolet rays as a light source. The lamp 52w incompletely cures the white ink by irradiating the white ink attached to the print medium with weak ultraviolet rays. That is, the pinning for the white ink is performed by the lamp 52w.

On the downstream side of the lamp 52w, four print heads 53t that discharge colorless and transparent ink as the first liquid are provided. Each print head 53t is formed with a nozzle row 532 composed of a large number of nozzles that discharge colorless and transparent ink as the first liquid. Two print heads 53t are arranged adjacent to each other in the main scanning direction and two in the sub scanning direction. By the nozzle rows 532 formed on the four print heads 53t, it is possible to discharge colorless and transparent ink at predetermined equal intervals onto a predetermined width area on the medium.

A lamp 52t is provided on the downstream side of the four print heads 53t that discharge colorless and transparent ink. The lamp 52t uses an LED that emits ultraviolet rays as a light source. The lamp 52t irradiates the ink adhering to the print medium with weak ultraviolet rays to incompletely cure the ink. That is, pinning is performed on the colorless and transparent ink by the lamp 52t.

Four sets of four print heads 23c for discharging color ink as the second liquid are provided on the downstream side of the lamp 52t. One set of print heads 23c ejects one type of color ink of cyan, magenta, yellow, and black different from the other sets.

A lamp 22c is provided between each set of print heads 23c. The lamp 22c incompletely cures the ink by irradiating the ink adhering to the print medium with weak ultraviolet rays. That is, the pinning is performed on the color inks of the respective colors by the lamp 22c.

A lamp 22d is provided further downstream of the print head 23c provided on the most downstream side. The lamp 22d completely cures the white ink, the transparent ink, and the color ink by irradiating the white ink, the transparent ink, and the color ink attached to the print medium with strong ultraviolet rays.

The control unit 58 is connected to the print heads 53w, 53t, 23c and the lamps 52w, 52t, 22c, 22d via a drive circuit (not shown). The control unit 58 is a computer including a processor, a RAM, a ROM, an input / output mechanism, and the like (not shown). The control unit 28 is R
By executing a print control program stored in the OM, white ink is ejected from the print head 53w to form an undercoat layer W1 on the print medium M as shown in FIG. As shown in FIG. 6B, the aggregation preventing protrusion T2 is formed on the print medium M. In addition, the control unit 58 executes a print control program to irradiate weak ultraviolet rays from the lamp 52w before causing the transparent ink to be ejected from the print head 53t to incompletely cure the white ink, so that the transparent ink is removed from the print head 53t. After the ejection, the transparent ink is incompletely cured by irradiating weak ultraviolet rays from the lamp 52t. Further, the control unit 58 discharges the color ink from the print head 23c to the area where the undercoat layer W1 and the aggregation preventing protrusion T2 are formed, and as shown in FIG. 6C, the ink droplets Cl, Cm, Cs
To form an image. Thereafter, the controller 58 irradiates strong ultraviolet rays from the lamp 22d to completely cure the white ink, the transparent ink, and the color ink.

In this embodiment, the period from when the transparent ink is ejected to the printing medium until the transparent ink is irradiated with ultraviolet rays is longer than that in the fourth embodiment. For this reason, the transparent ink droplets are more likely to spread as compared with the fourth embodiment from the time they adhere to the print medium to the time when they are cured. Therefore, the control unit 5
In No. 8, it is preferable to discharge a small amount of transparent ink from the print head 23t as compared with the fourth embodiment.

6). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, the configuration of the print head is not particularly limited as long as it can eject ink droplets. For example, the print head may be ejected by heating the ink droplets. The number of print heads and nozzle rows is appropriately designed according to the type of ink, the resolution, the width of the print area, and the like.

Further, for example, the liquid ejected from the print head is not limited to the ultraviolet curable ink, but may be a light curable ink that is cured by light in other wavelength ranges, or a liquid that is not intended for coloring (for example, forms a circuit pattern). A paste-like conductor). Moreover, you may use together photocurable ink and natural curable ink. The first liquid for forming the aggregation preventing protrusion may be a translucent color ink or an opaque ink other than white. The color of ink for forming an image is not limited to a combination of cyan, magenta, yellow, and black. For example, a highly saturated image may be formed using more types of color ink, or a single color ink (
For example, an image may be formed using only black. In addition, the liquid for forming the undercoat layer is not limited to white ink, and may be any liquid such as a liquid having a function of improving image visibility, enhancing wettability, or enhancing insulation. .

Further, the discharge amount of the second transparent ink discharged to the attention area may be continuously changed according to the discharge amounts of the first transparent ink and the opaque ink for each attention area.

The light source used for the irradiation unit is not limited to the LED, and any light source that emits light having a wavelength for curing the photocurable ink discharged from the print head may be used. Further, the lamp as the irradiation unit provided in the first carriage may be omitted, and the lamp as the irradiation unit may be provided only between the first carriage and the second carriage and downstream of the second carriage. Further, the lamp as the irradiation unit provided between the first carriage and the second carriage may be omitted, and the lamp as the irradiation unit may be provided only on the first carriage and downstream of the second carriage. Further, the lamp as the irradiation unit provided between the first carriage and the second carriage may be omitted, and the lamp as the irradiation unit may be provided only on the first carriage and downstream of the second carriage. Further, the lamp as the irradiation unit provided between the first carriage and the second carriage and the downstream of the second carriage may be omitted, and the lamp as the irradiation unit may be provided in the first carriage and the second carriage.

1, 2, 3, 5 ... printer, 11a, 11b, 11c, 11d ... transport roller, 12
a, 12b, 12c, 12d ... lamp, 13 ... print head, 13c, 13k, 13m, 1
3t, 13y ... nozzle row, 14 ... first carriage, 15 ... second carriage, 16 ... print head, 16t ... nozzle row, 17a, 17b, 17c ... motor, 18 ... controller, 19a ...
Endless belt, 19b ... pulley, 19c ... endless belt, 19d ... pulley, 22c ... ramp, 22d ... ramp, 22d ... print head, 22d ... ramp, 22t ... ramp, 23c ...
Print head, 23d ... print head, 23t ... print head, 28 ... control unit, 33 ... print head, 33w ... nozzle row, 36 ... print head, 38 ... control unit, 52t ... lamp, 52w ... lamp, 53t ... print head 53w ... print head, 58 ... control unit, 231 ... nozzle row, 2
32 ... Nozzle row, 233 ... Nozzle row, 531 ... Nozzle row, 532 ... Nozzle row, Cl ... Large dot, Cm ... Medium dot, Cs ... Small dot, M, M1, M2 ... Printing medium, T ... Ink layer, T
1, T2 ... Anti-aggregation protrusion, W1 ... Undercoat layer.

Claims (6)

A print head for discharging liquid;
A control unit that discharges the first liquid from the print head to form an aggregation preventing protrusion on the medium, and discharges the second liquid from the print head to a region including the aggregation preventing protrusion;
A printing apparatus comprising: The control unit decreases the discharge amount of the first liquid per region of interest as the wettability between the medium and the first liquid increases.
The printing apparatus according to claim 1. The liquid is a photocurable ink,
An irradiation unit for irradiating the photocurable ink attached to the medium with light;
The controller is configured to irradiate light from the irradiator to incompletely cure the first liquid before discharging the second liquid from the print head, and to discharge the second liquid from the print head. Irradiating light from the irradiation unit to completely cure the first liquid and the second liquid,
The printing apparatus according to claim 1 or 2. The first liquid and the second liquid are transparent inks,
The control unit discharges opaque ink from the print head to form an image on a medium,
The discharge amount of the first liquid is adjusted for each region of interest in accordance with the discharge amount of each region of interest of the opaque ink, and the second ink is discharged from the print head to the region where the opaque ink and the first liquid are discharged. To discharge liquid,
The printing apparatus according to any one of claims 1 to 3. The control unit causes the first liquid to be discharged from the print head only in a region where the discharge amount of the opaque ink is less than a predetermined value;
The printing apparatus according to claim 4. The second liquid is an opaque ink,
The control unit discharges a third liquid from the print head before discharging the first liquid to form an undercoat layer having higher wettability with respect to the second liquid than the medium on the medium, Discharging the second liquid from a print head to form an image on the medium;
The printing apparatus according to any one of claims 1 to 3.

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