Ink jet printer

Abstract

To provide an ink jet printer that can suppress degradation in print quality of a medium due to floating of the medium, can suppress degradation in print quality of the medium due to variation of a head gap, and can reduce manufacturing cost of a platen.SOLUTION: In this ink jet printer, a suction hole group 15b, which comprises many suction holes 15a that suck a medium placed on a platen 15 and are arranged in a main scanning direction, is formed in the platen 15. A straight linear groove 15c, which is recessed from a top face of the platen 15 and extends in the main scanning direction, is formed in a part of the platen 15 where the suction hole group 15 is formed. In the platen 15, only the straight linear groove 15c is formed as a groove recessed from the top face of the platen 15.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an inkjet printer for printing on a medium. [Background technology]

[0002] Conventionally, inkjet printers that print on long media are known (see, for example, Patent Document 1). The inkjet printer described in Patent Document 1 includes an ink head that ejects ink onto the medium, a carriage on which the ink head is mounted, a head moving mechanism that moves the carriage in the main scanning direction, a platen (support table) on which the medium is placed during printing, and an adsorption device that adsorbs the medium placed on the platen to the platen. The upper surface of the platen is a flat support surface that supports the medium.

[0003] In the inkjet printer described in Patent Document 1, a first groove to a fifth groove recessed downward are formed on the support surface of a platen. The first groove to the fifth groove are linear grooves extending in the main scanning direction. A large number of suction holes for sucking the medium are formed in the first groove to the fifth groove. In this inkjet printer, the first groove and the second groove are aligned in the sub-scanning direction. A plurality of connecting grooves connecting the first groove and the second groove are formed on the support surface. The connecting grooves are linear grooves inclined with respect to the main scanning direction and the sub-scanning direction.

[0004] In the inkjet printer described in Patent Document 1, suction holes are formed in the first to fifth grooves, which are linear and long in the main scanning direction, and the suction holes are less likely to be blocked by the medium placed on the support surface. Therefore, in this inkjet printer, the medium is sucked through the entire first to fifth grooves. Also, in this inkjet printer, the medium is sucked through a connecting groove formed between the first and second grooves. Therefore, in this inkjet printer, it is possible to prevent the medium placed on the platen from floating up, and as a result, it is possible to prevent a decrease in the print quality of the medium caused by the medium floating up. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-160826 A Summary of the Invention [Problem to be solved by the invention]

[0006] The inkjet printer described in Patent Document 1 is capable of suppressing deterioration in print quality of the medium caused by floating of the medium. However, since the inkjet printer described in Patent Document 1 has a connecting groove formed between the first groove and the second groove, there is a risk of variation in the distance between the portion of the medium placed on the platen between the first groove and the second groove and the bottom surface of the inkjet head that ejects the ink. In other words, there is a risk of variation in the head gap between the first groove and the second groove in this inkjet printer.

[0007] Therefore, even if the inkjet printer described in Patent Document 1 can suppress deterioration in print quality of the medium caused by floating of the medium, there is a risk of deterioration in print quality of the medium due to variations in the head gap between the first groove and the second groove. Also, in the inkjet printer described in Patent Document 1, multiple connection grooves that are inclined with respect to the main scanning direction and the sub-scanning direction are formed between the first groove and the second groove, which may increase the manufacturing cost of the platen.

[0008] Therefore, the object of the present invention is to provide an inkjet printer that is capable of suppressing deterioration in the printing quality of the medium due to the floating of the medium, as well as suppressing deterioration in the printing quality of the medium due to variations in the head gap, and that can reduce the manufacturing costs of the platen. [Means for solving the problem]

[0009] In order to solve the above problems, the inkjet printer of the present invention comprises an inkjet head which ejects ink onto a medium, a platen which is arranged below the inkjet head and on which the medium is placed during printing, and a suction mechanism for sucking the medium placed on the platen onto the platen, the platen being formed with a group of suction holes which are arranged in a main scanning direction which is the width direction of the medium and which serve to suck the medium placed on the platen, the portion of the platen where the group of suction holes is formed has a linear groove which is recessed from the top surface of the platen and extends in the main scanning direction, and the platen has only linear grooves which are recessed from the top surface of the platen.

[0010] In the inkjet printer of the present invention, a linear groove extending in the main scanning direction is formed in the portion of the platen where the suction hole group is formed, so that the suction hole is less likely to be blocked by the medium placed on the platen. Therefore, in the present invention, it is possible to suck the medium with the entire linear groove. Therefore, in the present invention, it is possible to suppress the lifting of the medium placed on the platen, and as a result, it is possible to suppress the deterioration of the print quality of the medium caused by the lifting of the medium. Also, in the present invention, since only linear grooves are formed in the platen as grooves recessed from the upper surface of the platen, there is no variation in the head gap between the first groove and the second groove as in the inkjet printer described in Patent Document 1. Therefore, in the present invention, it is possible to suppress the deterioration of the print quality of the medium caused by the variation in the head gap.

[0011] Furthermore, in the present invention, because only linear grooves are formed in the platen as grooves recessed from the top surface of the platen, it is possible to reduce the manufacturing costs of the platen compared to the inkjet printer described in Patent Document 1, in which multiple connecting grooves are formed between the first groove and the second groove. In this way, the present invention makes it possible to suppress deterioration in the print quality of the medium caused by the floating of the medium, suppress deterioration in the print quality of the medium caused by variations in the head gap, and reduce the manufacturing costs of the platen.

[0012] In addition, when a heater for heating the medium is built into the platen, if multiple connection grooves are formed between the first groove and the second groove as in the inkjet printer described in Patent Document 1, the medium and the platen do not come into contact in the areas where the connection grooves are formed, making it difficult to uniformize the temperature distribution of the heated medium. In contrast, in the present invention, it is easier to uniformize the temperature distribution of the heated medium compared to when multiple connection grooves are formed between the first groove and the second groove.

[0013] In the present invention, the inkjet printer includes, for example, a heater for heating the medium before printing. According to the inventor's investigation, when the medium before printing is heated, the medium tends to stretch depending on the thickness and type of the medium, and the medium placed on the platen tends to float up. However, in the present invention, even if the medium before printing is heated, it is possible to suppress the medium placed on the platen from floating up.

[0014] In the present invention, for example, the platen is formed with four suction hole groups and four linear grooves spaced apart in the sub-scanning direction perpendicular to the vertical direction and the main scanning direction, and the depth of the linear grooves is, for example, 0.3 mm or less. Effect of the Invention

[0015] As described above, the inkjet printer of the present invention makes it possible to suppress deterioration in the print quality of the medium caused by the floating of the medium, as well as suppress deterioration in the print quality of the medium caused by variations in the head gap, and reduce the manufacturing costs of the platen. [Brief description of the drawings]

[0016] [Figure 1] 1 is a side view illustrating a configuration of an inkjet printer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the platen shown in FIG. [Diagram 3] FIG. 3 is a plan view of a portion of the platen shown in FIG. 2. [Figure 4] FIG. 3 is a side view of the platen shown in FIG. 2. [Diagram 5] FIG. 5 is an enlarged view of part E in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] (Overall structure of an inkjet printer) FIG. 1 is a side view illustrating the configuration of an inkjet printer 1 according to an embodiment of the present invention.

[0019] The inkjet printer 1 (hereinafter, "printer 1") of this embodiment is, for example, an inkjet printer for commercial use. The printer 1 includes a printing mechanism 3 that prints on a long medium 2 (sheet-like medium 2) such as paper, fabric, or a resin sheet, a medium transport mechanism 4 that transports the medium 2, a payout roll holding section 6 that holds a payout roll 5 that is the medium 2 wound into a roll before printing, a take-up roll holding section 8 that holds a take-up roll 7 that is the medium 2 wound into a roll after printing, and a heater 9 that heats the medium 2 before printing.

[0020] If the Y direction in Fig. 1, which is perpendicular to the up-down direction (vertical direction), is defined as the "left-right direction", then the width direction of the medium 2 coincides with the left-right direction. In the following description, the X direction in Fig. 1, which is perpendicular to the up-down and left-right directions, is defined as the "front-to-back direction". Also, one side of the front-to-back direction, the X1 direction in Fig. 1, is defined as the "front" side, and the opposite side, the X2 direction in Fig. 1, is defined as the "rear" side. In this embodiment, the left-to-right direction (Y direction) is the main scanning direction, and the front-to-back direction (X direction) is the sub-scanning direction.

[0021] The printing mechanism 3 includes an inkjet head 12 (hereinafter referred to as "head 12") that ejects ink onto the medium 2, a carriage 13 on which the head 12 is mounted, a carriage drive mechanism that moves the carriage 13 back and forth in the main scanning direction (left and right direction), and a support frame (Y bar) 14 that supports the carriage 13 so that it can move in the left and right direction. The head 12 ejects ink downward. A plurality of nozzles that eject ink are formed on the lower surface of the head 12. The head 12 includes a piezoelectric element for ejecting ink from the nozzles. The carriage drive mechanism includes, for example, a belt that is partially fixed to the carriage 13, a pulley around which the belt is stretched, and a motor for rotating the pulley.

[0022] In this embodiment, the ink ejected from the head 12 is ultraviolet-curable UV ink. The carriage 13 is equipped with an ultraviolet irradiator (not shown) that irradiates ultraviolet rays toward the medium 2 to cure the UV ink ejected from the head 12. The ultraviolet irradiator is equipped with an ultraviolet LED chip. The carriage 13 is also equipped with an ink heating mechanism (not shown) that heats the UV ink to reduce the viscosity of the UV ink. The ink heating mechanism heats the UV ink supplied to the head 12.

[0023] The printing mechanism 3 also includes a platen 15 on which the medium 2 is placed during printing, a platen frame 16 that supports the platen 15 from below, and a suction mechanism 17 for sucking the medium 2 placed on the platen 15 to the platen 15. The platen 15 is disposed below the head 12 and the carriage 13. The platen 15 is formed in an elongated shape that is long and narrow in the left-right direction. The platen 15 is formed with a large number of suction holes 15a (see FIG. 3) for sucking the medium 2 placed on the platen 15. The suction holes 15a penetrate the platen 15 in the up-down direction. A large number of suction holes 15a are formed over almost the entire area of ​​the platen 15. The thickness direction of the medium 2 when printing is performed by the printing mechanism 3 coincides with the up-down direction. The specific configuration of the platen 15 will be described later.

[0024] The platen frame 16 is formed in a rectangular groove shape (square groove shape) that is elongated in the left-right direction. The platen frame 16 is formed by bending a thin metal plate such as a steel plate into a rectangular groove shape. The top surface of the platen frame 16 is open. The platen 15 is fixed to the upper end of the platen frame 16, and the top surface of the platen frame 16 is closed by the platen 15. A space is formed inside the platen frame 16, which is defined by the platen frame 16 and the platen 15. The suction hole 15a leads to this space.

[0025] The suction mechanism 17 includes a plurality of suction fans 18 disposed below the platen frame 16. The suction fans 18 are fixed to the bottom surface of the platen frame 16. The suction fans 18 suck air from the space defined by the platen frame 16 and the platen 15. That is, when the suction fans 18 are operated, the air inside the space defined by the platen frame 16 and the platen 15 is exhausted. When the air inside the space defined by the platen frame 16 and the platen 15 is exhausted, the medium 2 is sucked to the upper surface of the platen 15 and the medium 2 is held by the platen 15. The suction fans 18 are operated when printing on the medium 2.

[0026] The medium transport mechanism 4 transports the long medium 2 in the longitudinal direction of the medium 2. The medium transport mechanism 4 includes a transport roller 19 and a pad roller 20 that is disposed opposite the transport roller 19 and is biased toward the transport roller 19. The transport roller 19 and the pad roller 20 are disposed behind the platen 15. The transport roller 19 is connected to a drive mechanism that rotates the transport roller 19. The drive mechanism includes a motor as a drive source. The medium 2 is transported while being sandwiched between the transport roller 19 and the pad roller 20. The medium 2 before printing is transported from the rear side to the top surface of the platen 15, and the medium 2 after printing is transported from the top surface of the platen 15 to the front side.

[0027] The pay-out roll holding unit 6 is disposed below the printing mechanism 3. The pay-out roll holding unit 6 includes a rotating shaft 23 that is inserted into the inner periphery of the pay-out roll 5. The take-up roll holding unit 8 is disposed below the printing mechanism 3. The take-up roll holding unit 8 includes a rotating shaft 24 that is inserted into the inner periphery of the take-up roll 7, and a drive mechanism that rotates the rotating shaft 24. The heater 9 is disposed between the conveying roller 19 and the pad roller 20 and the pay-out roll holding unit 6 in the conveying direction of the medium 2. The heater 9 is covered by a cover. The heater 9 heats the medium 2 moving toward the platen 15.

[0028] (Platen configuration) Fig. 2 is a perspective view of the platen 15 shown in Fig. 1. Fig. 3 is a plan view of a portion of the platen 15 shown in Fig. 2. Fig. 4 is a side view of the platen 15 shown in Fig. 2. Fig. 5 is an enlarged view of a portion E in Fig. 4.

[0029] As described above, the platen 15 is formed in an elongated shape that is long and narrow in the left-right direction. The upper surface of the platen 15 is a medium placement surface on which the medium 2 is placed. As described above, the platen 15 is formed with a large number of suction holes 15a that penetrate the platen 15 in the up-down direction. The platen 15 also has suction hole groups 15b that are made up of a large number of suction holes 15a arranged in the left-right direction. In this embodiment, four suction hole groups 15b that are arranged at intervals in the front-rear direction (sub-scanning direction) are formed in the platen 15. Two of the four suction hole groups 15b are arranged adjacent to each other in front of the center of the platen 15 in the front-rear direction, and the remaining two suction hole groups 15b are arranged adjacent to each other behind the center of the platen 15 in the front-rear direction.

[0030] In the portion of the platen 15 where the suction hole group 15b is formed, a linear groove 15c is formed that is recessed downward from the upper surface of the platen 15 and extends in the left-right direction. That is, the suction hole group 15b is formed in the linear groove 15c. As described above, in this embodiment, four suction hole groups 15b arranged at intervals in the front-rear direction are formed in the platen 15, so that four linear grooves 15c arranged at intervals in the front-rear direction are formed in the platen 15. That is, the linear grooves 15c are formed in all the portions of the platen 15 where the suction hole groups 15b are formed. The hatched portion in FIG. 3 is the linear groove 15c. The linear groove 15c is a long groove in the left-right direction formed from the left end to the right end of the platen 15. That is, the linear groove 15c is formed in the entire area of ​​the platen 15 in the left-right direction.

[0031] The linear groove 15c is formed in a shallow angular groove shape (square groove shape). The suction hole 15a is formed, for example, at the center position of the linear groove 15c in the front-rear direction. The width (front-rear direction width) of the linear groove 15c is larger than the inner diameter of the suction hole 15a. For example, the width of the linear groove 15c is about five times the inner diameter of the suction hole 15a. The depth D of the linear groove 15c (specifically, the depth D of the linear groove 15c from the upper surface of the platen 15, see FIG. 5) is 0.3 (mm) or less. Only four linear grooves 15c are formed in the platen 15 as grooves recessed from the upper surface of the platen 15. That is, only the linear grooves 15c are formed in the platen 15 as grooves recessed from the upper surface of the platen 15.

[0032] (Main effects of this form) As described above, in this embodiment, linear grooves 15c extending in the left-right direction are formed in the portion of platen 15 where suction hole group 15b is formed, making it difficult for suction holes 15a to be blocked by medium 2 placed on platen 15. Therefore, in this embodiment, it is possible to suck medium 2 with the entire linear groove 15c. Therefore, in this embodiment, it is possible to prevent medium 2 placed on platen 15 from floating up, and as a result, it is possible to prevent a decrease in print quality of medium 2 caused by medium 2 floating up.

[0033] In this embodiment, the heater 9 heats the medium 2 before printing, which can cause the medium 2 to stretch easily depending on the thickness and type of the medium 2, making the medium 2 placed on the platen 15 more likely to float up. However, in this embodiment, even if the medium 2 before printing is heated, it is possible to prevent the medium 2 placed on the platen 15 from floating up.

[0034] In addition, according to the study of the present inventor, in this embodiment, the UV ink discharged from the head 12 is heated by the ink heating mechanism, reaction heat is generated in the UV ink discharged onto the medium 2, and the substrate of the ultraviolet LED chip generates heat when the medium 2 is irradiated with ultraviolet light, so that the medium 2 placed on the platen 15 is heated by these factors, and depending on the thickness and type of the medium 2, the medium 2 becomes more likely to stretch, and the medium 2 placed on the platen 15 becomes more likely to float up. In addition, according to the study of the present inventor, when a thin, inelastic, and weak medium 2 is used, when the medium 2 is made of polyvinyl chloride, and when the environmental temperature of the printer 1 is low, the medium 2 placed on the platen 15 becomes more likely to float up. However, in this embodiment, it is possible to suppress the medium 2 placed on the platen 15 from floating up.

[0035] In this embodiment, only the straight groove 15c is formed in the platen 15 as a groove recessed from the upper surface of the platen 15. Therefore, in this embodiment, the head gap does not vary between the first groove and the second groove as in the inkjet printer described in the above-mentioned Patent Document 1. Therefore, in this embodiment, it is possible to suppress a decrease in the print quality of the medium 2 caused by the variation in the head gap. Also, in this embodiment, since only the straight groove 15c is formed in the platen 15 as a groove recessed from the upper surface of the platen 15, it is possible to reduce the manufacturing cost of the platen 15 compared to the case where multiple connection grooves are formed between the first groove and the second groove as in the inkjet printer described in the above-mentioned Patent Document 1.

[0036] (Other embodiments) The above-described embodiment is one example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment and various modifications can be made without departing from the spirit and scope of the present invention.

[0037] In the above-mentioned embodiment, the linear groove 15c does not have to be formed over the entire area of ​​the platen 15 in the left-right direction. Also, in the above-mentioned embodiment, the depth D of the linear groove 15c may be deeper than 0.3 (mm). Furthermore, in the above-mentioned embodiment, two or three suction hole groups 15b arranged at intervals in the front-rear direction may be formed in the platen 15, or five or more suction hole groups 15b may be formed in the platen 15. Even in this case, the linear grooves 15c are formed in the same number as the number of suction hole groups 15b. Also, in the above-mentioned embodiment, the printer 1 may include a heater for heating the medium 2 after printing. Also, the printer 1 may not include the heater 9. [Explanation of symbols]

[0038] 1. Printer (inkjet printer) 2 medium 9 Heater 12 heads (inkjet heads) 15 Platen 15a Suction hole 15b Suction hole group 15c straight groove 17 Suction mechanism D Straight groove depth X sub-scanning direction Y Main scanning direction

Claims

1. an inkjet head that ejects ink onto a medium; a platen that is disposed below the inkjet head and on which the medium is placed during printing; and a suction mechanism that sucks the medium placed on the platen onto the platen, a suction hole group is formed in the platen, the suction hole group being made up of a number of suction holes arranged in a main scanning direction, which is a width direction of the medium, for sucking the medium placed on the platen; a linear groove is formed in a portion of the platen where the suction hole group is formed, the linear groove being recessed from an upper surface of the platen and extending in a main scanning direction; The inkjet printer according to claim 1, wherein the platen has only the linear grooves formed thereon as grooves recessed from an upper surface of the platen.

2. 2. The ink jet printer according to claim 1, further comprising a heater for heating the medium before printing.

3. 3. The inkjet printer according to claim 1, wherein the platen has four groups of suction holes and four linear grooves arranged at intervals in a sub-scanning direction perpendicular to the vertical direction and the main scanning direction.

4. 3. The ink jet printer according to claim 1, wherein the straight groove has a depth of 0.3 mm or less.

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