INKJET PRINTING DEVICE AND PRINTING METHOD

Abstract

 In this inkjet printing device, a control unit controls a head moving unit to move an inkjet head from a printing position for printing onto a recording medium to a retracted position retracted from the printing position, after printing by means of at least one scan of the inkjet head, and then controls an irradiator to irradiate ink on the recording medium with an active energy ray.

Description

Technical Field

[0001] The present invention relates to an inkjet printing apparatus and a printing method.

Background Art

[0002] Inkjet printing apparatuses use ink of an ultraviolet curable type to perform printing on a non-absorbent recording medium (medium) made of resin, glass, metal, or the like. Patent Literature (hereinafter referred to as "PTL") 1 describes a related art of an inkjet printing apparatus using ink of an ultraviolet curable type. The configuration of the inkjet printing apparatus described in PTL 1 will be briefly described as follows.

[0003] On the base, a conveyance stage (referred to as a placement table in PTL 1) on which a recording medium is placed and which conveys the recording medium in the sub-scanning direction is provided so as to be movable in the sub-scanning direction. An inkjet head for ejecting ink of an ultraviolet curable type onto the recording medium placed on the conveyance stage to perform printing is provided at a position above the base. The inkjet head includes, on the lower side thereof, a plurality of nozzles (referred to as inkjet nozzles in PTL 1) for ejecting the ink of an ultraviolet curable type. In addition, irradiators (referred to as UV curing apparatuses in PTL 1) which irradiate the ultraviolet curing type ink on the recording medium with ultraviolet rays are provided on the both sides of the inkjet head in the main scanning direction. Each irradiator is close to the inkjet head and is integrated with the inkjet head.

Citation List

Patent Literatures

[0004] PTL 1
Japanese Patent Publication Laid-Open No. 2022-168996

Summary of Invention

Technical Problem

[0005] However, in the inkjet printing apparatus described in PTL 1, each irradiator is close to the inkjet head, and thus, the ultraviolet rays irradiated from each irradiator are diffused and reflected, and leakage light of the ultraviolet rays may be irradiated to the side of the nozzles of the inkjet head. In such a case, clogging of the nozzles may occur due to curing of the ink of an ultraviolet curable type in the nozzles, leading to a decrease in print quality or malfunction of the inkjet head.

[0006] Accordingly, an object of the present invention is to provide an inkjet printing apparatus and a printing method each capable of achieving an improved print quality and a longer lifetime of an inkjet head while promoting space saving of the installation space of the inkjet printing apparatus.

Solution to Problem

[0007] One aspect of an inkjet printing apparatus of the present invention comprises:

a conveyance stage on which a recording medium is placed and which conveys the recording medium in a sub-scanning direction;

an inkjet head that includes a nozzle for ejecting ink of an active energy ray curable type and ejects the ink onto the recording medium to perform printing;

a head moving section that moves the inkjet head between a printing position, which is a position at which the inkjet head performs the printing on the recording medium, and a retracted position, which is a position to which the inkjet head is retracted from the printing position, in a main scanning direction;

an irradiator that irradiates the ink on the recording medium with an active energy ray; and

a control section that controls the head moving section such that the head moving section moves the inkjet head to the retracted position after the printing by at least one scanning of the inkjet head, and subsequently controls the irradiator such that the irradiator irradiates the ink on the recording medium with the active energy ray.

[0008] One aspect of a printing method of the present invention comprises: a printing process of performing printing on a recording medium by ejecting ink of an active energy ray curable type onto the recording medium from a nozzle of an inkjet head while conveying the recording medium placed on a conveyance stage in a sub-scanning direction; a retraction process of moving the inkjet head from a printing position, which is a position at which the inkjet head performs the printing on the recording medium, to a retracted position, which is a position to which the inkjet head is retracted from the printing position, after the printing by at least one scanning of the inkjet head; and an irradiation process of irradiating the ink on the recording medium with an active energy ray after the retraction process ends.

Advantageous Effects of Invention

[0009] According to the present invention, it is possible to achieve an improved print quality and a longer lifetime of an inkjet head while promoting space saving of the installation space of an inkjet printing apparatus.

Brief Description of the Drawings

[0010] 

[Fig. 1] Fig. 1 is a schematic plan view of an inkjet printing apparatus according to the present embodiment, illustrating a state before printing;

[Fig. 2] Fig. 2 is a schematic plan view of the inkjet printing apparatus according to the present embodiment, illustrating a state during the printing;

[Fig. 3] Fig. 3 is a schematic plan view of the inkjet printing apparatus according to the present embodiment, illustrating a state after the printing;

[Fig. 4] Fig. 4 is an enlarged cross-sectional diagram taken along line IV-IV in Fig. 2;

[Fig. 5] Fig. 5 is an enlarged cross-sectional diagram taken along line V-V in Fig. 3;

[Fig. 6] Fig. 6 is a control block diagram of the inkjet printing apparatus according to the present embodiment; and

[Fig. 7] Fig. 7 is a flowchart provided for describing a printing method according to the present embodiment.

Description of Embodiments

[0011] Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In the present embodiment, the X-axis direction is the main scanning direction and the left-right direction. One side in the X-axis direction is the left direction, and the other side in the X-axis direction is the right direction. The Y-axis direction is the sub-scanning direction and the front-rear direction. One side in the Y-axis direction is the front direction, and the other side in the Y-axis direction is the rear direction.

[0012] The configuration of an inkjet printing apparatus 10 according to the present embodiment will be described with reference to Figs. 1 to 5. Figs. 1 to 3 are schematic plan views of the inkjet printing apparatus 10 according to the present embodiment. Fig. 1 illustrates a state before printing, Fig. 2 illustrates a state during the printing, and Fig. 3 illustrates a state after the printing. Fig. 4 is an enlarged cross-sectional diagram taken along line IV-IV in Fig. 2. Fig. 5 is an enlarged cross-sectional diagram taken along line V-V in Fig. 3.

[0013] As illustrated in Figs. 1 to 5, the inkjet printing apparatus 10 according to the present embodiment is a printing apparatus that performs printing on a recording medium M such as a wiring board by ejecting ink toward the recording medium M while intermittently conveying the recording medium M in the Y-axis direction (the conveyance direction). The ink used in the inkjet printing apparatus 10 is, among inks of active energy ray curable types, radically polymerizable ink that contains a thermosetting substance and a gelling agent. The ink used in the inkjet printing apparatus 10 is, among radically polymerizable inks, gel ink of a UV curable type (hereinafter referred to as UV gel ink) and is a solder resist. The inkjet printing apparatus 10 may use ink of any other active energy ray curable type, such as gel ink of an electron beam curable type, instead of the UV gel ink.

[0014] The inkjet printing apparatus 10 includes a base 12, and the base 12 extends in the X-axis direction and the Y-axis direction. The longitudinal direction of the base 12 is the Y-axis direction, and the shorter direction of the base 12 is the X-axis direction. In addition, a pair of Y-axis guide rails 14 extending in the Y-axis direction is provided in parallel to each other in a right portion of the base 12 (a portion thereof on the one side in the X-axis direction). On the pair of Y-axis guide rails 14, a conveyance stage 16 on which the recording medium M is placed and which conveys the recording medium M in the Y-axis direction (the sub-scanning direction) is provided so as to be movable in the Y-axis direction. In other words, the conveyance stage 16 is provided in the right portion of the base 12 so as to be movable in the Y-axis direction via the pair of Y-axis guide rails 14. The conveyance stage 16 may include an adsorption mechanism (not illustrated) for adsorbing the recording medium M. The conveyance stage 16 may include a holding claw (not illustrated) that holds an edge portion of the recording medium M.

[0015] At an appropriate position of the base 12, a Y-axis motor 18 is provided as a stage moving section that moves the conveyance stage 16 in the Y-axis direction (the sub-scanning direction). An output shaft (not illustrated) of the Y-axis motor 18 is interlockingly connected to a part of the conveyance stage 16 via, for example, a ball screw mechanism (not illustrated), a rack and pinion mechanism (not illustrated), or the like. The Y-axis motor 18 includes a Y-axis encoder 20 as a first position detector that detects the position of the conveyance stage 16 in the Y-axis direction. The Y-axis encoder 20 detects the position of the recording medium M placed on the conveyance stage 16 in the Y-axis direction in addition to the position of the conveyance stage 16 in the Y-axis direction.

[0016] A gate-shaped frame 22 extending in the X-axis direction is erected in a central portion of the base 12 in the Y-axis direction so as to straddle the pair of Y-axis guide rails 14. The gate-shaped frame 22 includes: a pair of vertical portions 22a erected in the central portion of the base 12 in the Y-axis direction and separated from each other in the X-axis direction; and a horizontal portion 22b connecting an upper end portion of one vertical portion 22a and an upper end portion of the other vertical portion 22a and extending in the X-axis direction. In addition, a pair of X-axis guide rails 24 extending in the X-axis direction is provided in parallel to each other on the horizontal portion 22b of the gate-shaped frame 22. A carriage 26 is provided on the pair of X-axis guide rails 24 so as to be movable in the X-axis direction. In other words, the carriage 26 is provided on the horizontal portion 22b of the gate-shaped frame 22 so as to be movable in the X-axis direction via the pair of X-axis guide rails 24.

[0017] At an appropriate position of the horizontal portion 22b of the gate-shaped frame 22, an X-axis motor 28 as a carriage moving section for moving the carriage 26 in the X-axis direction (the main scanning direction) is provided. An output shaft (not illustrated) of the X-axis motor 28 is interlockingly connected to a part of the carriage 26 via, for example, a ball screw mechanism (not illustrated) or a rack and pinion mechanism (not illustrated). The X-axis motor 28 includes an X-axis encoder 30 as a second position detector that detects the position of the carriage 26 in the X-axis direction.

[0018] As illustrated in Figs. 4 and 5, the carriage 26 is provided with an inkjet head 32 for ejecting the UV gel ink onto the recording medium M from above to perform printing. In other words, the inkjet head 32 is provided in the horizontal portion 22b of the gate-shaped frame 22 so as to be movable in the X-axis direction via the carriage 26. The inkjet head 32 includes, on the lower side thereof, a plurality of nozzles 34 for ejecting the UV gel ink.

[0019] The arrangement width of the plurality of nozzles 34 (the arrangement length thereof in the X-axis direction) is larger than the placement width of the recording medium M (the placement length thereof in the X-axis direction) on the conveyance stage 16. Thus, the entire region of the recording medium M in the width direction (the X-axis direction) can be scanned by the inkjet head 32.

[0020] As illustrated in Figs. 1 to 5, the inkjet head 32 moves between a printing position PP (the position indicated by the solid lines in Figs. 1, 2, and 4), at which the inkjet head 32 performs printing, and a retracted position SP (the position indicated by the solid lines in Figs. 3 and 5), which is a position to which the inkjet head 32 is retracted from the printing position, in the X-axis direction (the main scanning direction). The X-axis motor 28 has a function as a head moving section that moves the inkjet head 32 between the printing position PP and the retracted position SP in the X-axis direction, in addition to a function as a carriage moving section that moves the carriage 26 in the X-axis direction. The X-axis encoder 30 as a second position detector detects the position of the carriage 26 in the X-axis direction, and also detects the position of the inkjet head 32 in the X-axis direction.

[0021] As illustrated in Figs. 4 and 5, a manifold (not illustrated) is provided in the inkjet head 32, and a common ink chamber (not illustrated) that accommodates the UV gel ink is formed in the manifold. A supply port (not illustrated) for supplying the UV gel ink to the common ink chamber is provided in one side portion of the inkjet head 32. A discharge port (not illustrated) for discharging the UV gel ink from a supply ink chamber is provided in the other side portion of the inkjet head 32.

[0022] Below the manifold in the inkjet head 32, a plurality of pressure chambers (not illustrated) is provided for the respective nozzles 34, and each pressure chamber communicates with the common ink chamber and the corresponding nozzle 34. Each pressure chamber is configured to be pressurized by the driving of a driving element such as a piezoelectric element or a heating element. Each nozzle 34 is configured to eject (spray) the UV gel ink when the corresponding pressure chamber is pressurized.

[0023] As illustrated in Figs. 3 and 5, a pair of supports 36 is erected in the vicinity of the front side of the gate-shaped frame 22 in the right portion of the base 12. An irradiator 38 extending in the X-axis direction is provided between an upper portion of one support 36 and an upper portion of the other support 36, and the irradiator 38 irradiates the UV gel ink on the recording medium M placed on the conveyance stage 16 with the ultraviolet rays UL from above. In other words, the irradiator 38 is provided in the vicinity of the front side of the gate-shaped frame 22 in the right portion of the base 12 via the pair of supports 36.

[0024] The irradiator 38 includes an irradiator main body 40 having a box shape provided between the upper portion of one support 36 and the upper portion of the other support 36. The irradiator main body 40 extends in the X-axis direction, and the lower side of the irradiator main body 40 is open. The irradiator 38 include a light source 42 provided in a ceiling portion in the irradiator main body 40, and the light source 42 irradiates ultraviolet rays UL as active energy rays. The light source 42 is a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, a black light, a cold-cathode tube, a light emitting diode (LED), or the like. The irradiation width of the ultraviolet rays UL (the irradiation length thereof in the X-axis direction) by the irradiator 38 is larger than the arrangement width of the plurality of nozzles 34 and is smaller than the stage width of the conveyance stage 16 (the stage length thereof in the X-axis direction).

[0025] Note that, in a case where the inkjet printing apparatus 10 uses ink of any other active energy ray curable type, such as gel ink of an electron beam curable type, the irradiator 38 irradiates active energy rays other than ultraviolet rays, such as electron beams.

[0026] The inkjet printing apparatus 10 may include a maintenance section (not illustrated) that causes the plurality of nozzles 34 to eject the UV gel ink to perform flushing in a state in which the inkjet head 32 is retracted to the retracted position. The inkjet printing apparatus 10 may include a cleaning section (not illustrated) that comes into contact with and cleans the plurality of nozzles 34 when the inkjet head 32 is moved in the X-axis direction.

[0027] Subsequently, a control configuration of the inkjet printing apparatus 10 will be described with reference to Figs. 2 to 6. Fig. 6 is a control block diagram of the inkjet printing apparatus 10 according to the present embodiment.

[0028] As illustrated in Fig. 6, the inkjet printing apparatus 10 includes a control section 44 that controls the Y-axis motor 18, the X-axis motor 28, the inkjet head 32, and the irradiator 38. The Y-axis encoder 20 and the X-axis encoder 30 are connected to the control section 44. The control section 44 integrally controls a series of operations of the inkjet printing apparatus 10, and includes a central processing unit (CPU) 46, a random access memory (RAM) 48, and a read only memory (ROM) 50. The ROM 48 stores various processing programs, and the CPU 46 reads various programs stored in the ROM 48, develops the read programs in the RAM 50, and controls a series of operations of the inkjet printing apparatus 10 according to the developed programs.

[0029] As illustrated in Figs. 4 to 6, the control section 44 controls the plurality of driving elements of the inkjet head 32 based on inputted print data. In other words, the control section 44 controls the ejection operation of the plurality of nozzles 34 based on inputted print data. In addition, the control section 44 controls the Y-axis motor 18 and the plurality of driving elements of the inkjet head 32 such that printing on every portion to be printed of the recording medium M ends by a plurality of times of scanning of the inkjet head 32. Note that, the control section 44 may control the Y-axis motor 18 and the plurality of driving elements of the inkjet head 32 such that printing on every portion to be printed of the recording medium M is performed by one scanning of the inkjet head 32.

[0030] As illustrated in Figs. 2 to 6, the control section 44 controls the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 from the printing position PP to the retracted position SP after the printing on every portion to be printed of the recording medium M. The control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the UV gel ink on the recording medium M with the ultraviolet rays UL after the inkjet head 32 is moved to the retracted position SP. Note that, the control section 44 may also control the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 to the retracted position SP after the printing by at least one scanning of the inkjet head 32, instead of after the printing on every portion to be printed of the recording medium M.

[0031] The control section 44 determines, based on the detection result from the Y-axis encoder 20 and the position of the irradiator 38 in the Y-axis direction, whether the recording medium M placed on the conveyance stage 16 is located directly below the irradiator 38. Then, the control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the ultraviolet rays UL, provided that the recording medium M placed on the conveyance stage 16 is located directly below the irradiator 38.

[0032] Subsequently, a printing method according to the present embodiment will be described with reference to Figs. 1 to 7. Fig. 7 is a flowchart provided for describing operations of the inkjet printing apparatus 10 according to the present embodiment.

[0033] As illustrated in Figs. 1 to 3, the printing method according to the present embodiment is a method of performing printing on the recording medium M, such as a wiring board, by using the inkjet printing apparatus 10. The printing method according to the present embodiment includes: (A) a preparation process, (B) a printing process, (C) a retraction process, and (D) an irradiation process. Then, specific content of each process of the printing method according to the present embodiment is as follows.

(A) Preparation process

[0034] As illustrated in Figs. 1, 6, and 7, the control section 44 controls the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 from the retracted position SP to the printing position PP (step S101 in Fig. 7). In addition, the recording medium M is placed at a predetermined position of the conveyance stage 16. Thus, the preparation for printing on the recording medium M by the inkjet printing apparatus 10 is completed.

(B) Printing process

[0035] As illustrated in Figs. 2, 4, 6, and 7, after the preparation process ends, the control section 44 controls the Y-axis motor 18 such that the Y-axis motor 18 intermittently moves the conveyance stage 16 in the Y-axis direction (the sub-scanning direction), thereby intermittently conveying the recording medium M placed on the conveyance stage 16 in the Y-axis direction. Along therewith, the control section 44 controls the plurality of driving elements of the inkjet head 32 such that the UV gel ink is ejected onto the recording medium M from the plurality of nozzles 34 to perform printing on the portion to be printed of the recording medium M (step S102 in Fig. 7).

[0036] Then, the control section 44 controls the Y-axis motor 18 and the plurality of driving elements of the inkjet head 32 so that the printing on every portion to be printed of the recording medium M is performed by a plurality of times of scanning of the inkjet head 32 (step 103 in Fig. 7). Note that, the printing on every portion to be printed of the recording medium M may also be performed by one scanning of the inkjet head 32.

(C) Retraction process

[0037] As illustrated in Figs. 3, 5, 6, and 7, after the printing process ends, the control section 44 controls the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 from the printing position PP to the retracted position SP (step S104 in Fig. 7). Thus, the inkjet head 32 can be separated to the one side in the X-axis direction (the left direction) with respect to the irradiator 38.

(D) Irradiation process

[0038] As illustrated in Figs. 3, 5, 6, and 7, after the retraction process ends, the control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the UV gel ink on every portion to be printed of the recording medium M with the ultraviolet rays UL from above (step S105 in Fig. 7). Thus, for example, a printing pattern such as an insulation pattern can be formed on the recording medium M by collectively curing the UV gel ink on every portion to be printed of the recording medium M.

[0039] In the irradiation process, the control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the ultraviolet rays UL from above, provided that the recording medium M placed on the conveyance stage 16 is located directly below the irradiator 38.

[0040] Note that, although the retraction process is started after the printing on every portion to be printed of the recording medium M, the retraction process may be started after the printing by at least one scanning of the inkjet head 32. In this case, the printing process, the retraction process, and the irradiation process are repeatedly executed until the UV gel ink on every portion to be printed of the recording medium M is irradiated with the ultraviolet rays UL.

[0041] According to the configuration of the inkjet printing apparatus 10 according to the present embodiment, the control section 44 controls the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 from the printing position PP to the retracted position SP after the printing by at least one scanning of the inkjet head 32. In addition, according to the configuration of the printing method according to the present embodiment, the inkjet head 32 is moved from the printing position PP to the retracted position SP after the printing by at least one scanning of the inkjet head 32. For this reason, it is possible to irradiate the UV gel ink on the recording medium M with the ultraviolet rays UL from the irradiator 38 in a state in which the inkjet head 32 is separated to the one side in the X-axis direction with respect to the irradiator 38. Thus, it is possible to suppress leakage light of the ultraviolet rays UL from reaching the side of the nozzles 34 of the inkjet head 32 to prevent clogging of the nozzles 34 due to the leakage light of the ultraviolet rays UL. Accordingly, the present embodiment makes it possible to achieve an improved print quality of the inkjet printing apparatus 10 and a longer lifetime of the inkjet head 32.

[0042] In addition, for the same reason, it is possible to dispose the irradiator 38 in a state of being close to the inkjet head 32 located at the printing position PP while suppressing leakage light of ultraviolet rays from reaching the side of the nozzles 34 of the inkjet head 32. Thus, it is possible to shorten the dimension of the inkjet printing apparatus 10 in the Y-axis direction and to promote space saving of the installation space of the inkjet printing apparatus 10.

[0043] Note that, in a case where the inkjet head 32 is fixed at the printing position PP, the irradiator 38 needs to be sufficiently separated from the inkjet head 32 in the Y-axis direction in order to suppress leakage light of ultraviolet rays from reaching the side of the nozzles 34 of the inkjet head 32. As a result, the dimension of the inkjet printing apparatus 10 in the Y-axis direction increases, and the inkjet printing apparatus 10 tends to increase in size.

[0044] That is, the present embodiment makes it possible to achieve an improved print quality of the inkjet printing apparatus 10 and a longer lifetime of the inkjet head 32 while promoting space saving of the installation space of the inkjet printing apparatus 10.

[0045] According to the configuration of the inkjet printing apparatus 10 according to the present embodiment, the control section 44 controls the X-axis motor 28 such that the X-axis motor 28 moves the inkjet head 32 from the printing position PP to the retracted position SP after the printing on every portion to be printed of the recording medium M. In addition, according to the configuration of the printing method according to the present embodiment, the inkjet head 32 is moved from the printing position PP to the retracted position SP after the printing on every portion to be printed of the recording medium M. For this reason, the UV gel ink on every portion to be printed of the recording medium M can be irradiated with the ultraviolet rays UL to collectively cure the UV gel ink on every portion to be printed of the recording medium M. Thus, the present embodiment makes it possible to improve the working efficiency of the inkjet printing apparatus 10.

[0046] According to the configuration of the inkjet printing apparatus 10 according to the present embodiment, the control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the recording medium M placed on the conveyance stage 16 with the ultraviolet rays UL, provided that the recording medium M is located directly below the irradiator 38. In addition, according to the configuration of the printing method according to the present embodiment, the control section 44 controls the irradiator 38 such that the irradiator 38 irradiates the ultraviolet rays UL, provided that the recording medium M placed on the conveyance stage 16 is located directly below the irradiator 38. For this reason, it is possible to suppress the diffusion of the ultraviolet rays UL irradiated from the irradiator 38 to further suppress leakage light of the ultraviolet rays from reaching the side of the nozzles 34 of the inkjet head 32. Thus, the present embodiment makes it possible to achieve a further improved print quality of the inkjet printing apparatus 10 and a much longer lifetime of the inkjet head 32.

[0047] According to the configuration of the inkjet printing apparatus 10 according to the present embodiment, the ink used in the inkjet printing apparatus 10 is radically polymerizable ink, and in particular, UV gel ink among radically polymerizable inks. For this reason, according to the present embodiment, even when the UV gel ink on every portion to be printed of the recording medium M is collectively cured after the printing of every portion to be printed of the recording medium M, it is possible to suppress the occurrence of bleeding and line thickening of the UV gel ink. Thus, the present embodiment makes it possible to stabilize the print quality of the inkjet printing apparatus 10. In a case where the recording medium M has a circuit pattern, it is possible to prevent the circuit pattern from being short-circuited.

[0048] According to the configuration of the inkjet printing apparatus 10 according to the present embodiment, the irradiation width of the ultraviolet rays UL by the irradiator 38 is larger than the arrangement width of the plurality of nozzles 34 and is smaller than the stage width of the conveyance stage 16. For this reason, it is possible to suppress the diffusion of the ultraviolet rays UL to further suppress leaked light of ultraviolet rays from reaching the side of the nozzles 34 of the inkjet head 32 while sufficiently ensuring that every portion to be printed of the recording medium M is irradiated with the ultraviolet rays UL. Thus, the present embodiment makes it possible to achieve a further improved print quality of the inkjet printing apparatus 10 and a much longer lifetime of the inkjet head 32.

[0049] Although the present embodiment has been specifically described above, the present invention is not limited to the above-described embodiment. Various modifications and changes can be made to the specific examples described in the above embodiment within the scope of the spirit of the present invention described in the claims.

[0050] The disclosure of Japanese Patent Application No. 2023-183885, filed on October 26, 2023, including the specification, drawings and abstract, is incorporated herein by reference in its entirety.

Industrial Applicability

[0051] The present invention is useful as an inkjet printing apparatus that is capable of achieving an improved print quality and a longer lifetime of an inkjet head.

Reference Signs List

[0052] 

10 Inkjet printing apparatus

12 Base

14 Y-axis guide rail

16 Conveyance stage

18 Y-axis motor (stage moving section)

20 Y-axis encoder (first position detector)

22 Gate-shaped frame

22a Vertical portion

22b Horizontal portion

24 X-axis guide rail

26 Carriage

28 X-axis motor (head moving section)

30 X-axis encoder (second position detector)

32 Inkjet head

34 Nozzle

36 Support

38 Irradiator

40 Irradiator main body

42 Light source

44 Control section

46 CPU

48 ROM 50 RAM

M Recording medium

PP Printing position

SP Retracted position

UL Ultraviolet ray (active energy ray)

Claims

1. An inkjet printing apparatus, comprising:

a conveyance stage on which a recording medium is placed and which conveys the recording medium in a sub-scanning direction;

an inkjet head that includes a nozzle for ejecting ink of an active energy ray curable type and ejects the ink onto the recording medium to perform printing;

a head moving section that moves the inkjet head between a printing position and a retracted position in a main scanning direction, the printing position being a position at which the inkjet head performs the printing on the recording medium, the retracted position being a position to which the inkjet head is retracted from the printing position;

an irradiator that irradiates the ink on the recording medium with an active energy ray; and

a control section that controls the head moving section such that the head moving section moves the inkjet head to the retracted position after the printing by at least one scanning of the inkjet head, and subsequently controls the irradiator such that the irradiator irradiates the ink on the recording medium with the active energy ray.

2. The inkjet printing apparatus according to claim 1, wherein
the control section controls the head moving section such that the head moving section moves the inkjet head to the retracted position after the printing on every portion to be printed of the recording medium, and subsequently controls the irradiator such that the irradiator irradiates the ink on the recording medium with the active energy ray.

3. The inkjet printing apparatus according to claim 1, wherein
the control section controls the irradiator such that the irradiator irradiates the active energy ray, provided that the recording medium is located directly below the irradiator.

4. The inkjet printing apparatus according to claim 1, further comprising a stage moving section that moves the conveyance stage in the sub-scanning direction, wherein
the control section controls the stage moving section such that the printing on every portion to be printed of the recording medium ends by a plurality of times of scanning of the inkjet head.

5. The inkjet printing apparatus according to claim 1, wherein
the ink of the active energy ray curable type is radically polymerizable ink containing a thermosetting substance and a gelling agent.

6. The inkjet printing apparatus according to claim 5, wherein
the radically polymerizable ink is ultraviolet gel ink, and the active energy ray is an ultraviolet ray.

7. The inkjet printing apparatus according to claim 1, wherein:

an arrangement width of a plurality of the nozzles is larger than a placement width of the recording medium on the conveyance stage, and

an irradiation width of the active energy ray by the irradiator is larger than the arrangement width of the plurality of nozzles and is smaller than a stage width of the conveyance stage.

8. A printing method, comprising:

a printing process of performing printing on a recording medium by ejecting ink of an active energy ray curable type onto the recording medium from a nozzle of an inkjet head while conveying the recording medium placed on a conveyance stage in a sub-scanning direction;

a retraction process of moving the inkjet head from a printing position to a retracted position after the printing by at least one scanning of the inkjet head, the printing position being a position at which the inkjet head performs the printing on the recording medium, the retracted position being a position to which the inkjet head is retracted from the printing position; and

an irradiation process of irradiating the ink on the recording medium with an active energy ray after the retraction process ends.

Drawing