Printing device

Abstract

To provide a printer capable of suppressing degradation of an image quality caused by bleeding and irregularity.SOLUTION: A printer includes a head, an energy imparting part, a moving device and a control device, wherein the control device discharges a liquid onto a printing surface from a head while relatively moving the head and a printing medium, imparts first energy to the liquid from the energy imparting part so that the liquid is made in a flow state having flowability while increasing its viscosity, while relatively moving the energy imparting part and the printing medium, imparts second energy to the liquid from the energy imparting part so that the liquid to which the first energy is imparted is cured, while relatively moving the energy imparting part and the printing medium, and determines an integrated energy amount of the first energy imparted onto the liquid on the printing surface from the energy imparting part until the second energy is imparted thereto after the first energy has been imparted thereto according to the state of the printing surface.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a printing apparatus.

Background Art

[0002] As a conventional printing apparatus, for example, the liquid ejection apparatus of Patent Document 1 is known. This liquid ejection apparatus includes a liquid ejection head that ejects a photocurable liquid onto a printing medium, and a light source unit that irradiates light onto the liquid on the printing medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the liquid ejection apparatus of Patent Document 1, an image is printed by curing the liquid on the printing medium with the light irradiated from the light source unit and fixing it on the printing medium. Here, when the illuminance of light on the printing medium is low, the liquid is likely to spread on the printing medium before it cures. Therefore, when it comes into contact with other liquids ejected onto the printing medium, the liquids are mixed together, leading to a deterioration in image quality due to bleeding.

[0005] On the other hand, when the illuminance of light on the printing medium is high, the liquid cures before it spreads sufficiently. As a result, the surface of the printing medium becomes uneven due to the cured product of the liquid, and diffused light is generated due to this unevenness, leading to a deterioration in image quality due to the diffused light.

[0006] In view of such a situation, an object of the present invention is to provide a printing apparatus capable of suppressing a deterioration in image quality caused by bleeding and unevenness.

Means for Solving the Problems

[0007] A printing apparatus according to an aspect of the present invention includes a head that discharges a liquid that cures by the application of energy onto a printing medium or a printing surface on the printing medium, an energy application unit that applies the energy to the liquid, a moving device that relatively moves the head, the energy application unit, and the printing medium, and a control device. The control device discharges the liquid from the head onto the printing surface while relatively moving the head and the printing medium, and applies a first energy from the energy application unit to the liquid so that the liquid is in a fluid state in which its viscosity increases but has fluidity while relatively moving the energy application unit and the printing medium. While relatively moving the energy application unit and the printing medium, a second energy is applied from the energy application unit to the liquid so as to cure the liquid to which the first energy has been applied, and according to the state of the printing surface, the integrated energy amount of the first energy applied from the energy application unit to the liquid on the printing surface until the second energy is applied after the first energy is applied is determined.

Advantages of the Invention

[0008] The present invention applies the energy for curing the liquid in two stages. In addition, in order to apply the integrated energy amount of the first energy according to the state of the printing surface to the liquid on the printing surface, the difference in the fluid state due to the difference in the state of the printing surface is reduced. Therefore, it is possible to suppress a decrease in image quality caused by bleeding and unevenness of the liquid regardless of the state of the printing surface.

[0009] The above objects, other objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and the overlapping description thereof will be omitted.

[0012] (Embodiment 1) <Configuration of the printing device> As shown in FIG. 1, the printing device 10 according to Embodiment 1 of the present invention is, for example, an inkjet printer that ejects a liquid from a head 20 toward a printing medium A and applies energy to the liquid from an energy application unit 30 to print an image. Note that the printing device 10 is not limited to an inkjet printer. Examples of the printing medium A include sheets such as cloth and paper. The liquid is a liquid such as ink that cures by the applied energy.

[0013] The printing device 10 includes a head unit 11, a moving device 40, and a control device 60 (FIG. 2). The head unit 11 has a head 20 and an energy application unit 30, and the moving device 40 has a conveyance device 50 and a carriage 42. Details of the control device 60 will be described later. The second direction in which the head 20 and the energy application unit 30 are arranged side by side is referred to as the left - right direction, the first direction intersecting (for example, orthogonal) the second direction is referred to as the front - rear direction, and the direction intersecting (for example, orthogonal) the left - right direction and the front - rear direction is referred to as the up - down direction. However, the arrangement of the printing device 10 is not limited to this.

[0014] The moving device 40 has a pair of moving rails 41, a carriage 42, a drive belt 43, and a moving motor 44, and moves the head unit 11 in the left - right direction. The pair of moving rails 41 are long members extending in the left - right direction, and are arranged parallel to each other so as to sandwich the head unit 11 therebetween in the front - rear direction. The carriage 42 mounts the head unit 11 and is supported so as to be movable in the left - right direction along the moving rail 41. The drive belt 43 is an endless belt, extends along the moving rail 41 in the left - right direction, is connected to the carriage 42, and is connected to the moving motor 44 via a pulley. When the moving motor 44 drives the drive belt 43, the carriage 42 reciprocates in the left - right direction along the moving rail 41. Thereby, the moving device 40 relatively moves the printing medium A, the head 20, and the energy applying unit 30 in the left - right direction.

[0015] The conveying device 50 has a stage 51, a conveying rail 52, a stage support base 53, and a conveying motor 54 (Fig. 2). The upper surface of the stage 51 faces the ejection surface 20a which is the lower surface of the head 20 and the lower surface of the energy applying unit 30, the printing medium A is placed on its upper surface, supports the printing medium A, and defines the gap between the printing medium A and the head 20 in the up - down direction. The conveying rail 52 extends in the front - rear direction. The stage support base 53 supports the stage 51, for example, is supported so as to be movable in the front - rear direction along the conveying rail 52, and is connected to the conveying motor 54. When the conveying motor 54 drives the stage support base 53, the stage 51 moves in the front - rear direction. Thereby, the conveying device 50 conveys the printing medium A forward, for example.

[0016] <Configuration of the head unit> As shown in Fig. 3, the head 20 has a plurality of nozzles 23, a liquid flow path 28, a flow path forming body 24, and a plurality of drive elements 25 (Fig. 2). The plurality of nozzles 23 are arranged at equal intervals in the front - rear direction to form a nozzle row. The plurality of nozzle rows are arranged at equal intervals in the left - right direction.

[0017] The flow path forming body 24 has, for example, a rectangular parallelepiped shape, and a nozzle 23 and a liquid flow path 28 are formed inside thereof. The nozzle 23 opens at the discharge surface 20a of the flow path forming body 24. The liquid flow path 28 is connected to the tank 29 (FIG. 1) and the nozzle 23, and has a common flow path 26 and a plurality of individual flow paths 27 therebetween. The common flow path 26 is connected to the tank 29, extends in the front-rear direction, and a plurality of individual flow paths 27 branch off from the common flow path 26. The upstream end of the individual flow path 27 is connected to the common flow path 26, and the downstream end thereof is connected to the nozzle 23. For this reason, the liquid flows from the tank 29 into the common flow path 26, branches into the individual flow paths 27 while flowing in the front-rear direction in the common flow path 26, and is supplied to the nozzle 23.

[0018] The drive element 25 is a piezoelectric element or the like, is provided corresponding to the individual flow path 27, and drives to vary the volume of the individual flow path 27. Thereby, a pressure for discharging the liquid from the nozzle 23 is applied to the liquid in the individual flow path 27. Thereby, the liquid lands on the printing surface D of the printing medium A or the printing surface D on the printing medium A. Note that the printing surface D will be described later.

[0019] The energy applying unit 30 is a device that applies energy to the liquid on the printing surface D. As this energy applying unit 30, hereinafter, a light irradiation unit that irradiates light as energy will be described. In this case, a photocurable liquid that is cured by light is used as the liquid.

[0020] However, the energy applying unit 30 is not limited to the light irradiation unit. For example, the energy applying unit 30 may be a radio wave generator that generates energy by heat energy and radio waves such as microwaves. In this case, a liquid that is cured by radio waves is used as the liquid.

[0021] Further, the energy applying unit 30 may be a heater that applies heat. Examples of this heater include a radiant heater, a warm air heater, and a contact heater. In this case, a liquid that is cured by heat, such as latex ink, is used as the liquid.

[0022] The energy applying unit 30 is disposed upstream of the head 20 in the direction in which the head 20 moves while discharging the liquid. For example, the head 20 discharges the liquid when moving to the left side and does not discharge the liquid when moving to the right side. In this case, the energy applying unit 30 is disposed on the right side, which is upstream of the head 20 in the moving direction to the left side during printing. The energy applying unit 30 irradiates light on the liquid on the printing surface D while moving following the head 20 that discharges the liquid onto the printing surface D.

[0023] The energy applying unit 30 has a plurality of light sources 33 and a circuit board 34 on which the light sources 33 are mounted. The circuit board 34 is made of, for example, an insulating material, has a rectangular flat plate shape, and has a lower surface on which the light sources 33 are mounted. The light source 33 is an energy source that irradiates light as energy, and is, for example, a light emitting element such as an LED, and is driven by the control device 60 to emit light (for example, ultraviolet light or infrared light) that cures the liquid discharged from the nozzle 23. The plurality of light sources 33 are arranged side by side in the front-rear direction to form a light source row. The plurality of light source rows are arranged at intervals in the left-right direction.

[0024] <Configuration of the control device> As shown in FIG. 2, the control device 60 has an arithmetic unit 61 and a storage unit 62. The storage unit 62 is a memory accessible by the arithmetic unit 61 and is composed of a RAM, a ROM, etc. The RAM temporarily stores various data such as printing data. The ROM stores programs for performing various data processes. Note that the control device 60 may be a single control device for centralized control or a plurality of control devices for distributed control. Also, the program may be stored in a storage medium other than the storage unit 62. Furthermore, the program may be stored in a single storage medium or may be divided and stored in a plurality of storage media.

[0025] The arithmetic unit 61 is composed of a processor such as a CPU and a circuit such as an integrated circuit such as an ASIC. By executing the program stored in the ROM, the control device 60 controls the drive element 25, the light source 33, the moving motor 44, and the conveyance motor 54 to execute printing processing.

[0026] Here, the control device 60 is connected to the drive element 25 of the head 20 via the head drive circuit 63 and controls the drive of the drive element 25. Thereby, the discharge of the liquid from the head 20 by the drive element 25 is controlled. Further, the control device 60 is connected to the light source 33 of the energy application unit 30 via the energy application drive circuit 64 and controls the drive of the light source 33. Thereby, the lighting and extinguishing of the light source 33 are controlled.

[0027] The control device 60 is connected to the moving motor 44 via the movement drive circuit 65 and controls the drive of the moving motor 44. The control device 60 is connected to the conveyance motor 54 via the conveyance drive circuit 66 and controls the drive of the conveyance motor 54. Thereby, the drive, stop, rotation speed, etc. of the moving motor 44 and the conveyance motor 54 are controlled.

[0028] The control device 60 is connected to an external power source B such as a commercial power source via a power supply circuit 67. The power supply circuit 67 converts the DC voltage from the external power source B into an output voltage for each part such as the drive element 25, the light source 33, the moving motor 44, and the conveyance motor 54 in the printing apparatus 10, and supplies the power of the output voltage to each part. The supply of this power is controlled by the control device 60.

[0029] <Printing Process> In such a printing apparatus 10, the control device 60 acquires print data and executes printing processing based on the print data. The print data includes image data (for example, raster data) indicating an image to be printed on the print medium A. The print data may be stored in the storage unit 62 or may be acquired from an external device such as a network, a computer, and a storage medium.

[0030] The control device 60 controls the movement motor 44 to perform a movement operation of moving the head unit 11 in the left - right direction. Also, the control device 60 controls the drive element 25 to perform a discharge operation of discharging liquid from the head 20. Further, the control device 60 controls the light source 33 to perform a radiation operation of radiating light from the light source 33. Furthermore, the control device 60 controls the conveyance motor 54 to perform a conveyance operation of conveying the printing medium A in the front - rear direction. Then, the printing device 10 alternately repeats scanning including the movement operation, the discharge operation, and the radiation operation, and the conveyance operation to proceed with the printing process.

[0031] <Scanning> In the scanning of the printing process, while the control device 60 relatively moves the head 20 and the printing medium A, the control device 60 discharges liquid from the head 20 onto the printing surface D. While the control device 60 relatively moves the energy application unit 30 and the printing medium A, the control device 60 causes the energy application unit 30 to apply a first energy to the liquid so that the liquid is in a fluid state in which its viscosity increases but has fluidity. While the control device 60 relatively moves the energy application unit 30 and the printing medium A, the control device 60 causes the energy application unit 30 to apply a second energy to the liquid so as to cure the liquid to which the first energy has been applied. The control device 60 determines the integrated energy amount of the first energy applied from the energy application unit 30 to the liquid on the printing surface D from when the first energy is applied until the second energy is applied according to the state of the printing surface D.

[0032] The integrated energy amount of the first energy is the product of the first energy applied to the liquid per unit area and per unit time and the time during which the first energy is applied to the liquid. The integrated energy amount of the second energy is the product of the second energy applied to the liquid per unit area and per unit time and the time during which the second energy is applied to the liquid.

[0033] For example, when the energy is light, the first energy is light with a first illuminance (mW / cm

[0033] , , , 2 ,

[0032] , 2 , <00​​) is the light. Also, the integrated energy amount of the first energy is the integrated light amount (mJ / cm 2 ) obtained by multiplying the first illuminance (mW / cm 2 ) of the light irradiated on the liquid per unit area and per unit time by the time (s) during which this light is irradiated on the liquid, and is hereinafter referred to as the first integrated light amount. The integrated energy amount of the second energy is the integrated light amount (mJ / cm 2 ) obtained by multiplying the second illuminance (mW / cm 2 ) of the light irradiated on the liquid per unit area and per unit time by the time (s) during which this light is irradiated on the liquid, and is hereinafter referred to as the second integrated light amount.

[0034] For example, the first illuminance is 10 or more and 500 or less (mW / cm 2 ), preferably 10 or more and 100 or less (mW / cm 2 ). The second illuminance is 1000 or more and 10000 (mW / cm 2 ), preferably 1000 or more and 3000 (mW / cm 2 ). The first integrated light amount is 0.6 or more and 30 or less (mJ / cm 2 ), preferably 0.6 or more and 5.9 or less (mJ / cm 2 ). The second integrated light amount is 60 or more and 600 or less (mJ / cm 2 ), preferably 60 or more and 190 or less (mJ / cm 2 ).

[0035] The first integrated light amount increases the viscosity of the liquid, and is the energy that makes the liquid in a flowing state with fluidity, and is determined according to the state of the printing surface D. The first integrated light amount is smaller than the integrated light amount that makes the surface of the liquid in a semi-cured state where the inside is flowable and the integrated light amount that makes the whole liquid in a fully cured state. Also, the second integrated light amount is the energy that fully cures the liquid in a flowing state and is predetermined.

[0036] In the flowing state, the viscosity of the liquid is higher than the viscosity of the liquid before the first integrated light amount is applied, such as when landing on the printing surface D, and the liquid has not reached the semi-cured state, and the surface of the liquid is in a state where it can flow. For example, the viscosity of the liquid before the application of the first integrated light amount is 5 or more and 30 or less (mPa·s), while the viscosity of the liquid in the flowing state after the application of the first integrated light amount is 10,000 or more and 100,000 or less (mPa·s).

[0037] As shown in FIGS. 4(a) to 4(d), the printing surface D includes any one of the surface of the printing medium A, the surface of the coating E on the printing medium A, and the surface of the layer facing the head 20 among the one or more layers of liquid layers C1 and C2 in the flowing state on the printing medium A.

[0038] Specifically, as shown in FIG. 4(a), when the coating E and the liquid layers C1 and C2 are not formed on the printing medium A and the surface of the printing medium A appears externally and faces the ejection surface 20a of the head 20 and the light source 33 of the energy application unit 30, the printing surface D is the surface of the printing medium A. In this case, the liquid is ejected from the head 20 and lands on the surface of the printing medium A which is the printing surface D, and further, the liquid on the surface of the printing medium A is irradiated with light of the first illuminance from the energy application unit 30. As a result, as shown in FIG. 4(c), a liquid layer C1 in the flowing state is formed on the printing medium A.

[0039] Also, as shown in FIG. 4(b), when the surface of the printing medium A is covered by the coating E and the surface of the coating E appears externally and faces the ejection surface 20a of the head 20 and the light source 33 of the energy application unit 30, the printing surface D is the surface of the coating E. In this case, the liquid is ejected from the head 20 and lands on the surface of the coating E which is the printing surface D, and further, the liquid on the surface of the coating E is irradiated with light of the first illuminance from the energy application unit 30. As a result, a liquid layer in the flowing state is formed on the coating E.

[0040] Further, as shown in FIG. 4(c), when the surface of the printing medium A is covered by a single liquid layer C1 and the surface of the liquid layer C1 is exposed to the outside and faces the ejection surface 20a of the head 20 and the light source 33 of the energy applying unit 30, the printing surface D is the surface of the liquid layer C1. In this case, liquid is ejected from the head 20 and lands on the surface of the liquid layer C1 which is the printing surface D, and the liquid that has landed on the surface of the liquid layer C1 is irradiated with light of the first illuminance from the energy applying unit 30. As a result, a liquid layer C2 in a flowing state is formed on the liquid layer C1 as shown in FIG. 4(d). In addition, when the surface of the printing medium A is covered by a coating E and further the surface of the coating E is covered by a single liquid layer C1, the surface of this liquid layer C1 may be used as the printing surface D.

[0041] Furthermore, as shown in FIG. 4(d), the surface of the printing medium A is covered by a plurality of (for example, two) liquid layers C1 and C2 in a flowing state, and the surface of the liquid layer C2 laminated on the liquid layer C1 is exposed to the outside and faces the ejection surface 20a of the head 20 and the light source 33 of the energy applying unit 30. In this case, the surface of the liquid layer C2 which is the farthest from the printing medium A in the vertical direction among the liquid layers C1 and C2 is used as the printing surface D. As a result, liquid is ejected from the head 20 and lands on the surface of the liquid layer C2 which is the printing surface D, and the liquid that has landed on the surface of the liquid layer C2 is irradiated with light from the energy applying unit 30. As a result, a liquid layer in a flowing state is formed on the liquid layer C2. In addition, when the surface of the printing medium A is covered by a coating E and further the surface of the coating E is covered by a plurality of liquid layers C1 and C2, the surface of this liquid layer C2 may be used as the printing surface D.

[0042] When the printing surface D is the surface of the printing medium A, the state of the printing surface D varies depending on the material of the printing medium A. When the printing surface D is the surface of the coating E on the printing medium A, the state of the printing surface D varies depending on the material of the coating E. When the printing surface D is the surface of the liquid layers C1 and C2 on the printing medium A, the state of the printing surface D varies depending on the materials of the liquid layers C1 and C2.

[0043] The material affects the ease of spreading of the liquid on the printing surface D, such as the printing medium A constituting the printing surface D, the coating E or the materials of the liquid layers C1 and C2, and the surface roughness. Depending on the state of the printing surface D, the ease of spreading of the liquid on the printing surface D is different, so the first integrated light quantity for making the liquid on the printing surface D in a flowing state is different.

[0044] As described above, this first integrated light quantity is the product of the first illuminance and the irradiation time of light on the liquid. Since this irradiation time is determined by a predetermined moving speed of the energy applying unit 30, it is predetermined. Therefore, the first integrated light quantity is determined according to the first illuminance. Thus, the relationship between the state of the printing surface D and the first illuminance is stored in advance in the storage unit 62. The control device 60 acquires the state of the printing surface D from the storage unit 62 or an external device, and when obtaining the first illuminance corresponding to the state of the printing surface D based on this predetermined relationship, the first integrated light quantity is determined by this first illuminance.

[0045] Here, the first integrated light quantity applied to the liquid on the printing surface D in the first state is larger than the first integrated light quantity irradiated on the liquid on the printing surface D in the second state where the liquid is more difficult to spread than the printing surface D in the first state. For example, the printing surface D in the first state is the surface of the printing medium A made of a material such as acrylic resin or glass, and the printing surface D in the second state is the surface of the coating E made of a material such as a white ink coating E applied on the printing medium A.

[0046] In this case, the control device 60 makes the first integrated light quantity for the liquid on the printing surface D in the first state larger than the first integrated light quantity for the liquid on the printing surface D in the second state. Thereby, the easier the liquid spreads on the printing surface D, the larger the first integrated light quantity becomes.

[0047] According to this, on the printing surface D in the first state where the liquid is likely to spread, by applying a large first integrated light amount to the liquid, the spread of the liquid in the flowing state on the printing surface D in the first state is reduced, and a decrease in image quality due to bleeding of the liquid can be suppressed. On the other hand, on the printing surface D in the second state where the liquid is difficult to spread, by applying a small first integrated light amount to the liquid, the unevenness of the liquid in the flowing state on the printing surface D in the second state is reduced, and a decrease in image quality due to the unevenness of the liquid can be suppressed.

[0048] Also, the first integrated light amount corresponding to the state of the printing surface D is applied to the liquid on the printing surface D, and the liquid becomes a flowing state. Thereby, the difference in the flowing state of the liquid corresponding to the state of the printing surface D is reduced, and a uniform flowing state of the liquid can be obtained regardless of the state of the printing surface D.

[0049] Then, the control device 60 changes the number of light sources 33 that turn off when applying light of the first illuminance according to the determined first integrated light amount. In this case, the plurality of light sources 33 are light-emitting elements that emit light of the same intensity as each other. The control device 60 controls the light sources 33 by the energy application drive circuit 64, supplies power to the light sources 33 to turn on the light sources 33, or stops supplying power to the light sources 33 to turn off the light sources 33.

[0050] The easier the liquid spreads on the printing surface D, the fewer the number of light sources 33 that turn off in the energy application unit 30 and the more the number of light sources 33 that turn on. Thereby, the first illuminance of the light from the energy application unit 30 increases, and the first integrated light amount applied to the liquid becomes larger. In this way, the first integrated light amount can be easily changed by turning on and off the light sources 33. Further, the control device 60 turns on or off the light sources 33 so that the light sources 33 that turn on in the energy application unit 30 are uniformly arranged. Thereby, the liquid is irradiated with uniform light from the energy application unit 30.

[0051] <Control Method of Printing Device> The control method of the printing apparatus 10 is executed by the control device 60, for example, in accordance with the flowchart of FIG. 5. In the examples of FIGS. 3 and 4(a), the control device 60 acquires print data (step S1), and discharges liquid from the head 20 while moving the head 20 to the left based on the print data (step S2). As a result, as shown in FIGS. 3 and 4(b), the liquid lands on the opposing region A1, which is the printing surface D that opposes the discharge surface 20a of the moving head 20, on the surface of the printing medium A.

[0052] Then, the control device 60 acquires the state of the surface of the printing medium A as the state of the printing surface D (step S3), and acquires a first illuminance corresponding to this state based on a predetermined relationship. A first integrated light amount is determined by this first illuminance and a predetermined irradiation time (step S4).

[0053] The control device 60 irradiates light with the first illuminance from the energy application unit 30 while moving the energy application unit 30 to the left following the head 20 (step S5). As a result, as shown in FIG. 4(c), the first integrated light amount corresponding to the state of the printing surface D is applied to the liquid on the printing surface D, and its viscosity increases to form a first liquid layer C1, which is a liquid layer in a fluid state having fluidity.

[0054] In the first liquid layer C1 in the fluid state shown in FIG. 6(a), the protrusion height of the liquid upward is lower than that of the liquid in the semi-cured state shown in FIG. 6(b), and by gently curving, the unevenness of the first liquid layer C1 becomes gentler than that of the layer formed by the semi-cured state liquid. Also, since the viscosity of the liquid in the first liquid layer C1 has increased compared to immediately after the liquid lands, the spread is suppressed, and in the first liquid layer C1, adjacent liquids are less likely to connect to each other than the liquids immediately after landing, and the liquid is less likely to ooze.

[0055] Here, since the first integrated light amount is larger as the liquid on the printing medium A is more likely to spread, an improvement in the balance between reduction of unevenness and reduction of bleeding is achieved. Also, since the first integrated light amount corresponding to the state of the printing surface D is applied to the liquid on the printing surface D, the difference in the flow state due to the difference in the state of the printing surface D is reduced, and the first liquid layer C1 in the flow state is formed on the printing surface D regardless of the state of the printing surface D.

[0056] Then, the control device 60 determines whether the liquid layer to be formed is the last one (step S6). If the first liquid layer C1 is not the last liquid layer (step S6: NO), the control device 60 moves the head unit 11 to the right without conveying the printing medium A. Then, as shown in FIG. 4(c), the control device 60 discharges the liquid while moving the head 20 to the left (step S2). In this case, the surface of the first liquid layer C1 in the flow state on the opposing region A1 faces the discharge surface 20a of the head 20 moving to the left as the printing surface D. Therefore, the liquid lands on the surface of the first liquid layer C1 which is the printing surface D.

[0057] Also, the control device 60 acquires the state of the surface of the first liquid layer C1 which is the printing surface D (step S3), and acquires the first illuminance corresponding to this state based on a predetermined relationship. The first integrated light amount is determined by this first illuminance (step S4). The control device 60 irradiates the first liquid layer C1 with light of the first illuminance while moving the energy application unit 30 to the left following the head 20 (step S5). As a result, as shown in FIG. 4(d), the liquid on the first liquid layer C1 receives the first integrated light amount corresponding to the surface state of the first liquid layer C1, and the second liquid layer C2 in the flow state is formed on the first liquid layer C1.

[0058] Here, since the first liquid layer C1 in FIG. 6(a) is in a flow state, the second liquid layer C2 laminated thereon is likely to spread. Therefore, the second liquid layer C2 can suppress unevenness more than the liquid layer formed on the liquid layer in a semi-cured state as shown in FIG. 6(b). As a result, the scattered light on the surface of the second liquid layer C2 is suppressed more than the scattered light on the surface of the liquid layer in FIG. 6(b).

[0059] Then, the control device 60 determines whether the formed liquid layer is the last one (step S6). Here, if the second liquid layer C2 is the last liquid layer (step S6: YES), as shown in FIGS. 3 and 4(d), the control device 60 moves the head unit 11 to the right without conveying the print medium A, and irradiates the first liquid layer C1 and the second liquid layer C2 with light of a second illuminance from the energy applying unit 30 without discharging liquid from the head 20 (step S7). As a result, a second integrated light amount is applied from the energy applying unit 30 to the first liquid layer C1 and the second liquid layer C2. Thereby, the liquids of the first liquid layer C1 and the second liquid layer C2 decrease or lose their fluidity and harden, and are fixed to the print medium A. For this reason, an image is printed on the print medium A with the liquid.

[0060] In this way, when an image is printed on the facing area A1 of the print medium A by the scanning operation, if the printing process based on the print data has not been completed (step S8: NO), the control device 60 conveys the print medium A forward (step S9). As a result, the discharge surface 20a of the head 20 that moves to the left faces a region A2 of the print medium A that is behind the facing area A1. Then, the control device 60 executes the processes from step S1 and subsequent steps on this facing area A2, and an image is printed. This scanning operation and the conveyance operation of the print medium A are alternately repeated, and an image corresponding to the print data is printed on the print medium A.

[0061] <Modification Example 1> In the above embodiment, the control device 60 changes the number of light sources 33 that are turned off when applying light of the first illuminance according to the determined first integrated light amount. Instead of this, the printing apparatus 10 according to Modification Example 1 further includes a filter 35 that reduces the intensity of the transmitted light, or a shutter 36 that blocks the transmitted light, as shown in FIGS. 7(a) and 7(b). The control device 60 changes the number of light sources 33 covered by the filter 35 or the shutter 36 when applying light of the first illuminance according to the determined first integrated light amount.

[0062] In the example of Fig. 7(a), the filter 35 has a rectangular flat plate shape and is an optical element that transmits light of a predetermined property among incident light, such as a polarizing filter, and absorbs or reflects the rest of the light without transmitting it. The filter 35 is disposed between the energy applying unit 30 and the stage 51 (Fig. 1) in the vertical direction so as to be able to cover the light source 33.

[0063] The length of the filter 35 in the front-rear direction is longer than the length of the light source array in which a plurality of light sources 33 are arranged in the front-rear direction in the energy applying unit 30. The front end of the filter 35 is disposed in front of the foremost light source 33 in the light source array, and the rear end of the filter 35 is disposed behind the rearmost light source 33 in the light source array. Thereby, the filter 35 can cover the light source 33 for each light source array.

[0064] The filter 35 moves in the left-right direction by the filter actuator 37 shown in Fig. 2. The filter actuator 37 is connected to the control device 60 via the filter drive circuit 68, and its movement is controlled by the control device 60.

[0065] All the light sources 33 of the energy applying unit 30 are lit. Here, for example, if the filter 35 is disposed on the right side of the arrangement range of the light sources 33 of the energy applying unit 30, all the light sources 33 of the energy applying unit 30 are not covered by the filter 35, and the light from all the light sources 33 is irradiated onto the printing medium A on the stage.

[0066] When the filter 35 is moved to the left, the light source 33 is covered by the filter 35 for each light source array. The light from the covered light source 33 passes through the filter 35, and the intensity of the transmitted light decreases. The other light sources 33 are disposed on the left side of the filter 35 and are not covered by the filter 35, and the intensity of their light does not decrease.

[0067] Therefore, as the filter 35 is moved to the left and the number of light sources 33 covered by the filter 35 increases, the first illuminance of the light irradiated from the energy applying unit 30 to the printing medium A decreases, and the first integrated light amount applied to the liquid decreases. Here, since the filter 35 covers the light source 33 for each light source row in the energy applying unit 30 that moves in the left - right direction, light can be irradiated onto the liquid evenly in both the left - right direction and the front - rear direction.

[0068] In the example of FIG. 7(b), the shutter 36 is an optical element that does not transmit light and moves in the left - right direction by the shutter actuator 38 shown in FIG. 2. The shutter actuator 38 is connected to the control device 60 via the shutter drive circuit 69, and its movement is controlled by the control device 60.

[0069] The filter 35 reduces the intensity of light and transmits light, while the shutter 36 blocks the transmitted light. Otherwise, the shutter 36 is the same as the filter 35. Therefore, as the shutter 36 is moved to the left and the number of light sources 33 covered by the shutter 36 increases, the first illuminance of the light irradiated from the energy applying unit 30 to the printing medium A decreases, and the first integrated light amount applied to the liquid decreases. Here, since the shutter 36 covers the light source 33 for each light source row in the energy applying unit 30 that moves in the left - right direction, light can be irradiated onto the liquid evenly in both the left - right direction and the front - rear direction.

[0070] Note that, as shown in FIG. 8(a), the filter 35 may be divided into a plurality of (for example, three) filter portions 35a, 35b, 35c. In this case, the plurality of filter portions are arranged side - by - side in the front - rear direction, and each filter portion can be independently moved in the left - right direction by the filter actuator 37.

[0071] For example, among the three filter portions, the central filter portion 35b disposed between the front-end filter portion 35a and the rear-end filter portion 35c is arranged on the left side rather than the front-end filter portion 35a and the rear-end filter portion 35c. As a result, the number of light sources 33 covered by the central filter portion 35b is larger than the number of light sources 33 covered by the front-end filter portion 35a and the number of light sources 33 covered by the rear-end filter portion 35c. For this reason, the intensity of the light radiated from the central portion of the energy application portion 30 covered by the central filter portion 35b is reduced, and the illuminance of the light irradiated from this central portion to the center of the printing surface D is reduced.

[0072] Therefore, at the center of the printing surface D, the light of a plurality of light sources 33 overlaps and the illuminance tends to increase. By reducing the intensity of the light radiated from the central portion of the energy application portion 30, the illuminance of the light on the printing surface D can be made uniform. As shown in FIG. 8(b), the shutter 36 may also be divided into a plurality of shutter portions 36a, 36b, and 36c in the same manner as the filter 35. Thereby, the illuminance of the light on the printing surface D is made uniform.

[0073] <Modification 2> In the above embodiment, the control device 60 changes the number of light sources 33 that are turned off when applying light of the first illuminance according to the determined first integrated light amount. Instead of this, in the printing apparatus 10 according to Modification 2, the control device 60 changes the intensity of the light irradiated from the light source 33 when applying light of the first illuminance according to the determined first integrated light amount.

[0074] In this case, the light source 33 is a light-emitting element whose light emission intensity can be changed according to the supplied power. The light-emitting element of the light source 33 emits light of a smaller intensity as the supplied power is smaller. As a result, the first illuminance of the light irradiated on the liquid on the printing surface D decreases, and the first integrated light amount applied to the liquid decreases. The control device 60 controls the power supplied to the light source 33 by the energy application drive circuit 64 shown in FIG. 2. This control includes, for example, control for changing the light intensity by PWM control.

[0075] Thus, by adjusting the supply power of the light source 33, the first integrated light quantity applied from the energy applying unit 30 to the liquid on the printing surface D can be easily changed. Also, all the light sources 33 in the energy applying unit 30 may be controlled collectively, or the light sources 33 may be controlled individually. For example, if the intensity of the light sources 33 is increased toward both ends in the front-rear direction, the illumination on the printing surface D can be made uniform.

[0076] <Modification Example 3> In the printing apparatus 10 of the above-described embodiment and all modification examples, the head unit 11 had one head 20 and one energy applying unit 30. In contrast, in the printing apparatus 10 according to Modification Example 3, as shown in FIG. 9(a), the head unit 11 has one head 20 and two energy applying units 30.

[0077] In the example of FIG. 9, the energy applying unit 30 has a first energy applying unit 31 and a second energy applying unit 32. The first energy applying unit 31 is disposed on the right side of the head 20 and behind the second energy applying unit 32. The light source 33 has a first light source 33a of the first energy applying unit 31 and a second light source 33b of the second energy applying unit 32.

[0078] The control method of this printing apparatus 10 is executed by the control device 60, for example, along the flowchart of FIG. 10. In FIG. 10, the process of step S10 is executed between step S6 and step S7 of FIG. 5 without executing step S9 of FIG. 5. In this step S10, the printing medium is conveyed.

[0079] Specifically, as shown in FIG. 10(a), the control device 60 acquires print data (step S1), discharges liquid from the head 20 that moves to the left based on the print data (step S2), and lands the liquid on the opposing area A1 of the print medium A which is the printing surface D. Then, the control device 60 acquires the state of the surface of the print medium A as the state of the printing surface D (step S3), and determines the first integrated light quantity according to this state (step S4).

[0080] The control device 60 causes the energy applying unit 30 that follows the head 20 to irradiate the liquid on the printing surface D with light of a first illuminance (step S5). As a result, the liquid on the printing surface D receives a first integrated light amount and becomes a flowing state, and a first liquid layer C1 in the flowing state is formed in the opposing region A1.

[0081] If this first liquid layer C1 is not the last layer formed in the opposing region A1 (step S6: NO), the control device 60 repeats the processes of steps S2 to S5 to form a liquid layer in the flowing state in the opposing region A1. On the other hand, if the first liquid layer C1 is the last layer formed in the opposing region A1 (step S6: YES), as shown in FIG. 10(b), the control device 60 conveys the printing medium A forward (step S10). As a result, in the opposing region A1, the first liquid layer C1 faces the second energy applying unit 32, and in the opposing region A2 behind the opposing region A1, the printing medium A faces the head 20.

[0082] Then, the control device 60 causes the second energy applying unit 32 to emit light of a second illuminance while moving the head unit 11 back to the right side and then to the left side (step S7). As a result, in the opposing region A1, the first liquid layer C1 receives a second integrated light amount and cures, and an image is printed in the opposing region A1.

[0083] Further, if the printing process has not ended (step S8: NO), the control device 60 discharges the liquid from the head 20 (step S2). Then, the control device 60 acquires the state of the surface of the printing medium A in the opposing region A2 as the state of the printing surface D (step S3), determines a first integrated light amount corresponding to this state, and then causes the first energy applying unit 31 to emit light of a first illuminance (step S5). As a result, in the opposing region A2, after the liquid lands on the printing medium A which is the printing surface D, this liquid is irradiated with light of the first illuminance, and a first liquid layer C1 in the flowing state is formed on the printing surface D. If this first liquid layer C1 is not the last layer formed in the opposing region A1 (step S6: NO), the processes after step S10 are executed, and an image is printed in the opposing region A2.

[0084] In this way, the head unit 11 has one head 20, a first energy applying unit 31, and a second energy applying unit 32. Thereby, while moving the head unit 11, it is possible to simultaneously cure the liquid layer in the opposing region A1 by irradiating light with the second illuminance and form a liquid layer in a flowing state in the opposing region A2 by irradiating light with the first illuminance.

[0085] <Other Modification Examples> In all of the above embodiments and modification examples, the first integrated light amount is adjusted by the first illuminance according to the state of the printing surface D. However, the first integrated light amount may be adjusted by the irradiation time according to the state of the printing surface D. For example, the control device 60 obtains a moving speed corresponding to the state of the printing surface D based on a predetermined correspondence relationship in which the state of the printing surface D and the moving speed of the head unit 11 correspond to each other. Here, the slower the moving speed of the head unit 11, the longer the irradiation time of the light from the energy applying unit 30 of the head unit 11 to the liquid, and the greater the first integrated light amount applied to the liquid.

[0086] In all of the above embodiments and modification examples, after forming the second liquid layer C2 in a flowing state, the control device 60 moves the head unit 11 to the right and irradiates light with the second illuminance from the energy applying unit 30 without discharging the liquid from the head 20. However, after forming the second liquid layer C2 of the liquid in a flowing state, the control device 60 may irradiate light with the second illuminance from the energy applying unit 30 without discharging the liquid from the head 20 while moving the head unit 11 to the right and then to the left.

[0087] In all of the above embodiments and modifications, the moving device 40 moves the head unit 11 relative to the printing medium A without moving the printing medium A in the left - right direction. In contrast, the moving device 40 may move the stage 51 relative to the head 20 without moving the head 20 in the left - right direction, so as to relatively move the printing medium A on the stage 51 and the head unit 11. Also, the moving device 40 may move the head 20 and the stage 51 in the left - right direction to relatively move the printing medium A on the stage 51 and the head unit 11.

[0088] In all of the above embodiments and modifications, a piezoelectric element is used for the drive element 25, but it is not limited thereto. For the drive element 25, for example, a thermal actuator such as a heating resistor that generates bubbles, and an electrostatic actuator such as an electrode that generates electrostatic force may be used.

[0089] Note that all of the above embodiments may be combined with each other as long as they do not exclude each other. Also, from the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present invention. Without departing from the spirit of the present invention, the details of its structure and / or function can be substantially changed.

Industrial Applicability

[0090] The printing device according to the present invention is useful as a printing device or the like that can suppress deterioration of image quality due to bleeding and unevenness.

Explanation of Reference Numerals

[0091] 10: Printing device 20: Head 30: Energy application unit 31: First energy application unit 32: Second energy application unit 33: Light source 35: Filter 36: Shutter 40: Moving device 42: Carriage 50: Conveying device 60: Control device

Claims

1. A head that discharges a liquid that cures upon application of energy onto a printing medium or a printing surface on the printing medium; An energy application unit that applies the energy to the liquid; A moving device that relatively moves the head, the energy application unit, and the printing medium; A control device, and comprising: The control device: While relatively moving the head and the printing medium, a process of discharging the liquid from the head onto the printing surface; While relatively moving the energy application unit and the printing medium, a process of applying a first energy from the energy application unit to the liquid so that the liquid is in a flowing state in which its viscosity increases but has fluidity, and by repeating this process, a plurality of liquid layers containing the liquid are stacked and arranged on the printing surface; While relatively moving the energy application unit and the printing medium, a second energy is applied from the energy application unit to the liquid in the liquid layer to which the first energy has been applied so as to cure the liquid in the liquid layer; Before each of the processes of applying the first energy to the liquid: When arranging the first liquid layer on the surface of the printing medium, the amount of the first energy applied from the energy application unit to the liquid on the surface of the printing medium is determined in advance according to the state of the surface of the printing medium, and When stacking and arranging two or more liquid layers on the printing surface, the integrated energy amount of the first energy applied from the energy application unit to the liquid on the printing surface until the second energy is applied after applying the first energy is determined in advance according to the state of the surface of the uppermost liquid layer formed immediately before. A printing apparatus.

2. The printing surface is any one of the surface of the printing medium, the surface of a coating film on the printing medium, and the surface of a layer of the liquid in the flowing state of one or more layers on the printing medium that faces the head. The printing apparatus according to Claim 1.

3. When the printing surface is the surface of the printing medium, the state of the printing surface changes depending on the material of the printing medium, When the printing surface is the surface of the coating film on the printing medium, the state of the printing surface changes depending on the material of the coating film. The printing apparatus according to claim 2, wherein when the printing surface is the surface of the liquid layer on the printing medium, the state of the printing surface changes depending on the material of the liquid layer.

4. When determining the integrated energy amount, the control device makes the integrated energy amount applied to the liquid on the printing surface in the first state larger than the integrated energy amount applied to the liquid on the printing surface in the second state, where the liquid is less likely to spread than on the printing surface in the first state, according to any one of claims 1 to 3.

5. The energy applying unit has a plurality of light sources that irradiate light as the energy. The control device changes the number of the light sources that are turned off when applying the first energy according to the determined integrated energy amount, according to any one of claims 1 to 4.

6. The energy applying unit has a plurality of light sources that irradiate light as the energy. The energy applying unit further includes a filter that reduces the intensity of the transmitted light or a shutter that blocks the transmitted light. The control device changes the number of the light sources covered by the filter or the shutter when applying the first energy according to the determined integrated energy amount, according to any one of claims 1 to 4.

7. The energy applying unit has a light source that irradiates light as the energy. The control device changes the intensity of the light irradiated from the light source when applying the first energy according to the determined integrated energy amount, according to any one of claims 1 to 4.

8. The energy applying unit has a first energy applying unit that is arranged in a first direction and applies the first energy to the liquid, and a second energy applying unit that applies the second energy to the liquid. The first energy applying unit is arranged parallel to the head in a second direction orthogonal to the first direction. The moving device has a conveying device that conveys the printing medium in the first direction, and a carriage that mounts the head, the first energy applying unit, and the second energy applying unit and moves in the second direction. The control device While moving the carriage in the second direction, the liquid is discharged from the head onto the printing surface, and the first energy is applied to the liquid on the printing surface from the first energy applying unit. The print medium is conveyed in the first direction. The printing apparatus according to any one of claims 1 to 7, wherein while moving the carriage in the second direction, the second energy is applied to the liquid in the liquid layer located at the uppermost position on the printing surface among the plurality of liquid layers from the second energy applying unit, and the liquid is further discharged onto the printing surface from the head.

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