JP7651366B2 - Inspection method for nozzle condition of inkjet printer and inkjet printer - Google Patents

Description

The present invention relates to a method for inspecting the nozzle condition of an inkjet printer and an inkjet printer.

Technology for checking the state of the nozzles of an inkjet printer by printing a test chart has been known for some time. For example, Patent Document 1 discloses an inkjet recording device that uses a printer to print a test chart containing chart groups for yellow, cyan, magenta, and black on paper, and then reads the printed test chart with an image reading device. This inkjet recording device is said to be able to accurately detect the position of nozzles with ejection defects, such as nozzle clogs, and the degree of the defect.

JP 2019-149610 A

Some inkjet printers are designed to eject transparent ink. The condition of the nozzles that eject transparent ink is also inspected using a test chart, but transparent ink test charts have poor visibility. Therefore, it is difficult to inspect nozzles that eject transparent ink using a test chart.

The present invention has been made in consideration of these points, and its purpose is to provide a method for inspecting the state of nozzles in an inkjet printer that can easily inspect the state of nozzles that eject transparent ink. It is also an object of the present invention to provide an inkjet printer that can easily inspect the state of nozzles that eject transparent ink.

The method for inspecting the nozzle state of an inkjet printer disclosed herein is a method for inspecting the state of the first nozzles in an inkjet printer equipped with a recording head having a plurality of first nozzles that eject a transparent first ink and a plurality of second nozzles that eject a colored second ink, and includes a first step of ejecting the first ink from the plurality of first nozzles toward a recording medium and causing the first ink to land on the recording medium, a second step of curing the first ink that has landed on the recording medium after the first step, and a third step of ejecting the second ink from the plurality of second nozzles toward the recording medium and causing the second ink to land near the landing position of the first ink, forming a test chart, and a fourth step of determining the state of the first nozzles based on the wet state of the ink dots of the second ink in the test chart.

According to the above-mentioned method for inspecting the nozzle state of an inkjet printer, the colored second ink lands on the test chart near the landing position of the transparent first ink. If there is an abnormality in the first nozzle that ejects the first ink, and the first ink is not ejected or the landing position is shifted, the wetting state of the second ink changes compared to when the first ink is ejected normally. Therefore, by inspecting the wetting state of the colored second ink, it is possible to inspect the state of the first nozzle that ejects the transparent first ink. Therefore, according to the above-mentioned method for inspecting the nozzle state of an inkjet printer, it is possible to easily inspect the state of the first nozzle that ejects the transparent first ink.

The inkjet printer disclosed herein includes a support table for supporting a recording medium, a recording head, and a control device. The recording head has a plurality of first nozzles for ejecting a transparent first ink toward the recording medium on the support table, and a plurality of second nozzles for ejecting a colored second ink toward the recording medium on the support table. The control device includes a mode selection unit configured to be able to select a mode for creating a test chart for inspecting the state of the plurality of first nozzles, and a test chart creation unit that receives a selection in the mode selection unit and creates the test chart on the recording medium. The test chart creation unit includes a first creation unit and a second creation unit. The first creation unit ejects the first ink from the plurality of first nozzles toward the recording medium, and lands the first ink on the recording medium. The second creation unit ejects the second ink from the plurality of second nozzles toward the recording medium after the first ink that has landed on the recording medium has hardened, and lands the second ink near the landing position of the first ink.

With the inkjet printer, if you select a mode for creating a test chart to inspect the state of the first nozzle, you can create a test chart in which the colored second ink lands near the landing position of the transparent first ink. This provides the same effect as the inspection method described above.

1 is a perspective view of a printer according to an embodiment; FIG. 2 is a front view of the printer with the front cover open. 4 is a plan view illustrating a schematic configuration of the lower surface of the carriage. FIG. FIG. 2 is a block diagram of a printer. 11 is a flowchart showing a process for creating a test chart and inspecting the state of a first nozzle. FIG. 2 is a schematic plan view of a test chart. FIG. 2 is a schematic vertical cross-sectional view of a test chart. FIG. 2 is a plan view illustrating a row of ink dots of cyan ink.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described here is, of course, not intended to limit the present invention in any particular way. In addition, the same reference numerals will be used to designate components and parts that perform the same function, and duplicate descriptions will be omitted or simplified as appropriate.

1 is a perspective view of an inkjet printer (hereinafter, referred to as the printer) 10 according to an embodiment. In the following description, unless otherwise specified, the side away from the printer 10 when viewed from the front is the front, and the side approaching the printer 10 is the rear. The terms left, right, top, and bottom refer to the left, right, top, and bottom when viewed from the front of the printer 10. Also, the symbols F, Rr, L, R, U, and D in the drawings refer to the front, back, left, right, top, and bottom, respectively. The symbol Y in the drawings indicates the main scanning direction. The main scanning direction Y is the left-right direction. The symbol X indicates the sub-scanning direction. The sub-scanning direction X is the front-rear direction. The symbol Z indicates the up-down direction. The main scanning direction Y, the sub-scanning direction X, and the up-down direction Z are perpendicular to each other. However, the above directions are merely defined for the convenience of description, and do not limit the installation mode of the printer 10, nor limit the present invention.

In this embodiment, the printer 10 is an inkjet printer. In this embodiment, the term "inkjet" refers to inkjet printers using various conventional methods, including various continuous methods such as a binary deflection method or a continuous deflection method, and various on-demand methods such as a thermal method or a piezoelectric element method.

As shown in FIG. 1, the printer 10 is formed in a box shape. In this embodiment, the printer 10 includes a case 11 and a front cover 12. FIG. 2 is a front view showing the printer 10 with the front cover 12 open. As shown in FIG. 2, an opening is formed in the front of the case 11. The front cover 12 is provided so as to be able to open and close the opening of the case 11. Here, the front cover 12 is supported by the case 11 so as to be able to rotate around its rear end. The front cover 12 is provided with a window portion 12a. The window portion 12a is formed, for example, from a transparent acrylic plate. The user can see the internal space of the case 11 through the window portion 12a.

As shown in FIG. 2, the printer 10 includes a flatbed 20, a bed moving device 25, a carriage 30, a carriage moving device 35, a recording head 40, a light irradiation device 50, and a control device 100 (see FIG. 1).

The flatbed 20 is a support table that supports the substrate. The printer 10 according to this embodiment is a so-called flatbed type printer. The flatbed 20 is a flat plate-shaped member. The flatbed 20 extends in the main scanning direction Y and the sub-scanning direction X. The flatbed 20 is disposed in the internal space of the case 11, approximately at the center in the main scanning direction Y. The substrate is placed on the top surface of the flatbed 20. When inspecting the state of the nozzles 41G to 41K (see FIG. 3) of the recording head 40, a recording medium 5 for printing a test chart is used as the substrate. The recording medium 5 is, for example, recording paper. However, the recording medium 5 is not particularly limited as long as it is capable of printing a test chart.

A bed moving device 25 is disposed below the flatbed 20. The bed moving device 25 moves the flatbed 20 in the sub-scanning direction X and the vertical direction Z. The flatbed 20 is supported from below by the bed moving device 25. The bed moving device 25 includes a sub-scanning direction moving mechanism 25X and a vertical direction moving mechanism 25Z. The vertical direction moving mechanism 25Z supports the flatbed 20 and moves it in the vertical direction Z. The vertical direction moving mechanism 25Z is supported from below by the sub-scanning direction moving mechanism 25X. The sub-scanning direction moving mechanism 25X supports the vertical direction moving mechanism 25Z and moves it in the sub-scanning direction X. The sub-scanning direction moving mechanism 25X is an example of a first moving device that moves the recording medium 5 in the sub-scanning direction X relative to the recording head 40 by moving at least one of the recording head 40 and the recording medium 5 on the flatbed 20. The configuration of the bed moving device 25 is not limited. For example, the vertical positional relationship between the sub-scanning direction movement mechanism 25X and the vertical direction movement mechanism 25Z may be reversed.

The carriage 30 is equipped with a recording head 40 and a light irradiation device 50. The carriage 30 is disposed above the flatbed 20. The carriage 30 is disposed so as to face the flatbed 20. The carriage 30 is moved in the main scanning direction Y by the carriage moving device 35. The carriage moving device 35 is an example of a second moving device that moves the recording head 40 in the main scanning direction Y relative to the recording medium 5 by moving at least one of the recording head 40 and the recording medium 5 on the flatbed 20. The carriage moving device 35 includes a guide rail 36, a belt 37, left and right pulleys (not shown), and a carriage motor 38 (see FIG. 4).

As shown in FIG. 2, the guide rail 36 extends in the main scanning direction Y. The carriage 30 is slidably engaged with the guide rail 36. An endless belt 37 is fixed to the carriage 30. The belt 37 is wound around pulleys (not shown) provided on the right and left sides of the guide rail 36. A carriage motor 38 is attached to one of the pulleys. When the carriage motor 38 is driven, the pulley rotates and the belt 37 runs. This causes the carriage 30 to move in the main scanning direction Y along the guide rail 36.

Figure 3 is a plan view showing the underside of the carriage 30. As shown in Figure 3, the recording head 40 is provided on the underside of the carriage 30. The recording head 40 faces the flatbed 20. Here, the recording head 40 has five ink heads 40G, 40C, 40M, 40Y, and 40K. However, the number of ink heads that the recording head 40 has is not limited. Here, the ink heads 40G, 40C, 40M, 40Y, and 40K all extend in the sub-scanning direction X. The ink heads 40G, 40C, 40M, 40Y, and 40K are arranged side by side in the main scanning direction Y.

The ink head 40G has a plurality of first nozzles 41G. The plurality of first nozzles 41G are aligned in the sub-scanning direction X to form a first nozzle row 42G.

The ink heads 40C to 40K other than the ink head 40G are arranged at different positions from the ink head 40G in the sub-scanning direction X. The ink heads 40G and the ink heads 40C to 40K are arranged in a so-called staggered arrangement. Here, some of the ink heads 40C to 40K overlap with the ink head 40G in the sub-scanning direction X, and the other parts are offset from the ink head 40G. The ink head 40C has a plurality of second nozzles 41C. The plurality of second nozzles 41C are aligned in the sub-scanning direction X to form the second nozzle row 42C. The ink head 40M has a plurality of third nozzles 41M. The plurality of third nozzles 41M are aligned in the sub-scanning direction X to form the third nozzle row 42M. The ink head 40Y has a plurality of fourth nozzles 41Y. The plurality of fourth nozzles 41Y are aligned in the sub-scanning direction X to form the fourth nozzle row 42Y. The ink head 40K has a plurality of fifth nozzles 41K. The plurality of fifth nozzles 41K are aligned in the sub-scanning direction X to form a fifth nozzle row 42K.

In FIG. 3, the number of the first nozzles 41G to the fifth nozzles 41K forming the first nozzle row 42G to the fifth nozzle row 42K is shown as 10 each, but in reality, they are formed in greater numbers and at a higher density (for example, 360 nozzles per inch = 360 dpi). The number and pitch of the first nozzles 41G to the fifth nozzles 41K forming the first nozzle row 42G to the fifth nozzle row 42K are not limited. Here, the pitch of the first nozzles 41G in the first nozzle row 42G to the pitch of the fifth nozzles 41K in the fifth nozzle row 42K are all the same pitch P.

Nozzles 41G-41K are each connected to a pressure chamber in which ink is stored. Recording head 40 is provided with a number of actuators that expand/contract the pressure chambers. The actuators are, for example, piezoelectric elements. Ink is ejected from nozzles 41G-41K when the actuators are driven to expand/contract the pressure chambers. A drive waveform for driving the actuators is applied to the actuators. The drive waveform includes a number of portions corresponding to ink droplets of different sizes (for example, large, medium, and small). The actuators are configured to be able to change the size of the ink droplets ejected depending on the portion of the drive waveform to which it is applied.

The first nozzle row 42G to the fifth nozzle row 42K are each connected to an ink cartridge 45 by an ink tube (not shown). As shown in FIG. 2, the ink cartridge 45 is housed in an ink cartridge housing section 46. Different ink cartridges 45 are connected to the first nozzle row 42G to the fifth nozzle row 42K. In this embodiment, the ink ejected from the recording head 40 is a photocurable ink. Here, the photocurable ink is an ultraviolet-curable ink that cures when irradiated with ultraviolet light. There are no particular limitations on the components, characteristics, etc. of the photocurable ink.

In this embodiment, the first nozzles 41G are connected to an ink cartridge 45 that stores a transparent gloss ink. The first nozzles 41G eject the gloss ink toward the recording medium 5 on the flatbed 20. The second nozzles 41C are connected to an ink cartridge 45 that stores a cyan ink. The second nozzles 41C eject the cyan ink toward the recording medium 5 on the flatbed 20. Similarly, the third nozzle 41M, the fourth nozzle 41Y, and the fifth nozzle 41K eject magenta ink, yellow ink, and black ink, respectively, toward the recording medium 5 on the flatbed 20. However, the type of ink ejected from the nozzles of the multiple nozzle rows is not particularly limited, except that the ink ejected from the nozzles of at least one nozzle row is a transparent ink, and the ink ejected from the nozzles of at least one nozzle row is a colored ink.

The light irradiation device 50 is provided on the carriage 30. Here, the light irradiation device 50 is provided to the left of the recording head 40. The light irradiation device 50 irradiates light that cures the photocurable ink toward the recording medium 5 on the flatbed 20. As shown in FIG. 3, the light irradiation device 50 includes a light source 51 that generates light and an irradiation port 52 that irradiates the light from the light source 51 toward the outside. The light source 51 is composed of, for example, a plurality of ultraviolet irradiation LEDs. Here, the irradiation port 52 is an opening provided with a cover that allows light to pass through. However, the irradiation port 52 may be a simple opening that is not covered by a cover or the like. The irradiation port 52 extends in the sub-scanning direction X.

Figure 4 is a block diagram of the printer 10 according to this embodiment. As shown in Figure 4, the control device 100 is electrically connected to the sub-scanning direction movement mechanism 25X, the vertical direction movement mechanism 25Z, the carriage motor 38, the recording head 40, and the light source 51 of the light irradiation device 50, and controls their operations. The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, it includes an interface (I/F) that receives print data and the like from an external device such as a host computer, a central processing unit (CPU) that executes instructions of a control program, a ROM (read only memory) that stores a program executed by the CPU, a RAM (random access memory) used as a working area for expanding the program, and a storage device such as a memory that stores the above-mentioned program and various data. Note that the control device 100 does not necessarily have to be provided inside the printer 10, and may be, for example, a computer or the like that is installed outside the printer 10 and is connected to the printer 10 via wire or wireless communication so as to be able to communicate with the printer 10.

As shown in FIG. 4, the control device 100 includes a mode selection unit 110, an image creation unit 120, and a test chart creation unit 130. The mode selection unit 110 is configured to be able to select one of a print mode in which an image is created based on print image data and a test print mode in which a test chart is created for inspecting the states of the first nozzle 41G to the fifth nozzle 41K. The image creation unit 120 creates an image based on the print image data in response to the selection in the mode selection unit 110. The test chart creation unit 130 creates a test chart on the recording medium 5 in response to the selection in the mode selection unit 110. The control device 100 may include processing units other than those described above, but illustration and description thereof will be omitted here.

As shown in FIG. 4, the test chart creation unit 130 includes a first creation unit 131, a second creation unit 132, a first curing processing unit 133, a second curing processing unit 134, and a dot control unit 135 as processing units for creating a test chart for inspecting the state of the first nozzles 41G that eject the gloss ink. The first creation unit 131 ejects gloss ink from the multiple first nozzles 41G toward the recording medium 5, and causes the gloss ink to land on the recording medium 5. In detail, the first creation unit 131 controls the carriage moving device 35 to move the recording head 40 in the main scanning direction Y, while causing the gloss ink to land on the recording medium 5. As a result, multiple ink dots (before curing) of gloss ink arranged in a matrix in the main scanning direction Y and the sub-scanning direction X are formed.

After the gloss ink that has landed on the recording medium 5 has hardened, the second creation unit 132 ejects colored ink from a nozzle of one of the nozzle rows that ejects colored ink toward the recording medium 5, and causes the colored ink to land near the landing position of the gloss ink. Here, after the gloss ink that has landed on the recording medium 5 has hardened, the second creation unit 132 ejects cyan ink from the nozzle 41C of the second nozzle row 42C toward the recording medium 5. However, the ink ejected by the second creation unit 132 may be colored ink, and is not limited to cyan ink. After the gloss ink has been ejected by the first creation unit 131 and before the cyan ink has been ejected by the second creation unit 132, the first curing processing unit 133 controls the light irradiation device 50 to irradiate light onto the gloss ink on the recording medium 5, thereby curing the gloss ink on the recording medium 5. After the cyan ink is ejected by the second production unit 132, the second curing processing unit 134 controls the light irradiation device 50 to irradiate the cyan ink on the recording medium 5 with light, thereby curing the cyan ink on the recording medium 5.

In this embodiment, the second creation unit 132 is configured to control the bed moving device 25 to position the recording medium 5 at a position where the landing position of the cyan ink is close to the landing position of the gloss ink in the sub-scanning direction X, and then eject the cyan ink from the multiple second nozzles 41C. In general, the second creation unit 132 moves the flat bed 20 so that the landing area of the gloss ink in the sub-scanning direction X and the second nozzle row 42C overlap. In detail, the second creation unit 132 controls the bed moving device 25 to position the recording medium 5 at a position where the landing positions of the gloss ink and the landing positions of the gloss ink alternate with each other in the sub-scanning direction X. Thereafter, the second creation unit 132 ejects the cyan ink from the second nozzles 41C while controlling the carriage moving device 35 to move the recording head 40 in the main scanning direction Y. As a result, multiple ink dots (before curing) of cyan ink arranged in a matrix in the main scanning direction Y and the sub-scanning direction X are formed. The cyan ink dots are formed offset in the sub-scanning direction X from the positions where the gloss ink dots are formed by 1/2P, half the nozzle pitch P.

The dot control unit 135 controls the actuator connected to the first nozzle 41G to control the dot diameter of the hardened gloss ink to be equal to or greater than 1/2P, half the pitch P of the first nozzle 41G to the fifth nozzle 41K, and less than the nozzle pitch P. The portion of the drive waveform used when ejecting the gloss ink is pre-selected so that the dot diameter after hardening is equal to or greater than half the nozzle pitch of the first nozzle 41G to the fifth nozzle 41K, and less than the nozzle pitch. The droplet size of the cyan ink is not particularly limited, but may be the same droplet size as the gloss ink.

Although not shown in the figure, the test chart creation unit 130 also includes a processing unit that creates a test chart for inspecting the state of the second nozzle 41C that ejects cyan ink. This processing unit creates a test chart for inspecting the state of the second nozzle 41C by the same processing as the first creation unit 131 and the first curing processing unit 133. In detail, the processing unit controls the carriage moving device 35 to move the recording head 40 in the main scanning direction Y, while controlling the recording head 40 to land the cyan ink on the recording medium 5. As a result, a plurality of ink dots (before curing) of cyan ink arranged in a matrix in the main scanning direction Y and the sub-scanning direction X are formed. After that, the processing unit controls the light irradiation device 50 to irradiate the cyan ink on the recording medium 5 with light, thereby curing the cyan ink on the recording medium 5. The same applies to the creation of test charts for inspecting the states of the third nozzle 41M to the fifth nozzle 41K. These test charts may be created in different places on the same recording medium 5, or may be created on different recording media 5.

[Creating a test chart]
In the following, a process of creating a test chart (hereinafter, simply referred to as test chart T, see FIG. 6) for inspecting the state of the first nozzle 41G that ejects the gloss ink and inspecting the state of the first nozzle 41G based on the test chart T will be described. FIG. 5 is a flowchart showing the process of creating the test chart T and inspecting the state of the first nozzle 41G. FIG. 6 is a schematic plan view of the test chart T. Although not shown in FIG. 5, a test print mode is selected at the start of the flowchart. As shown in FIG. 5, in the process of creating the test chart T, in step S01, gloss ink is ejected from a plurality of first nozzles 41G toward the recording medium 5, and the gloss ink is landed on the recording medium 5. In step S01, since the recording head 40 is moved in the main scanning direction Y, the ink dots (before curing) of the gloss ink are formed so as to be arranged in a matrix in the main scanning direction Y and the sub-scanning direction X. The symbol Dg in FIG. 6 indicates the ink dots Dg of the gloss ink. 6, in the test chart T, the pitch of the multiple gloss ink dots Dg in the sub-scanning direction X is equal to the nozzle pitch P of the first nozzle 41G to the fifth nozzle 41K. The pitch of the multiple gloss ink dots Dg in the main scanning direction Y is determined by the moving speed of the carriage 30 and the time interval at which the gloss ink is ejected from the first nozzle 41G.

In step S02, the gloss ink that has landed on the recording medium 5 is irradiated with light from the light irradiation device 50 to harden the gloss ink. In this embodiment, the gloss ink is ejected while the carriage 30 moves to the right, and during that time, the light irradiation device 50 arranged to the left of the recording head 40 irradiates light. Therefore, the gloss ink that has landed on the recording medium 5 is sequentially irradiated with light. However, in step S02, the gloss ink may be irradiated with light after more time has passed since the gloss ink was ejected. In this way, the gloss ink wets and spreads on the recording medium 5 before it hardens, so that the diameter of the ink dots Dg of the hardened gloss ink can be increased. The diameter of the ink dots Dg of the hardened gloss ink can be controlled by the time from the ejection of the gloss ink to the hardening of the gloss ink, as well as the size of the gloss ink droplets. In step S02, the diameter of the ink dots Dg of the hardened gloss ink is controlled to be half or more of the nozzle pitch P of the first nozzle 41G to the fifth nozzle 41K and less than the nozzle pitch P.

In the next step S03A, the bed moving device 25 is controlled to move the flatbed 20 in the sub-scanning direction X. As a result, in general, the recording medium 5 is moved so that the landing area of the gloss ink in the sub-scanning direction X overlaps with the second nozzle row 42C. In detail, the recording medium 5 is moved to a position where the landing positions of the gloss ink and the cyan ink alternate with each other in the sub-scanning direction X. That is, the recording medium 5 is moved to a position where the landing positions of the gloss ink and the cyan ink are shifted by 1/2P, half of the nozzle pitch P, in the sub-scanning direction X. In step S03B, cyan ink is ejected from the second nozzle 41C while the recording head 40 is moved in the main scanning direction Y. As a result, in steps S03A and S03B, the cyan ink lands near the landing position of the gloss ink (here, a position shifted by 1/2P, half of the nozzle pitch P, in the sub-scanning direction X) as shown in FIG. 6.

The symbol Dc in FIG. 6 indicates an ink dot Dc of cyan ink. As shown in FIG. 6, in the test chart T, the pitch of the multiple ink dots Dc of cyan ink in the sub-scanning direction X is also equal to the nozzle pitch P of the first nozzle 41G to the fifth nozzle 41K. As shown in FIG. 6, the ink dots Dc of cyan ink are formed offset in the sub-scanning direction X by 1/2P, half the nozzle pitch P, from the formation position of the ink dots Dg of gloss ink. The pitch of the multiple ink dots Dc of cyan ink in the main scanning direction Y is determined by the movement speed of the carriage 30 and the time interval at which cyan ink is ejected from the second nozzle 41C, but here it is set to the same as the pitch of the ink dots Dg of gloss ink in the main scanning direction Y.

The forming step of the test chart T further includes step S03C of irradiating the cyan ink that has landed on the recording medium 5 with light to cure the cyan ink. Step S03C is performed after steps S03A and S03B and before step S04. In step S03C, the ink dots Dc of the cyan ink that have landed between the ink dots Dg of the gloss ink are irradiated with light from the light irradiation device 50 to cure them. This completes the test chart T for inspecting the state of the first nozzle 41G that ejects the gloss ink. Test charts for other inks may be created in a different location on the recording medium 5 in the same manner as steps S01 and S02. However, in FIG. 5, the steps of creating test charts for inspecting the states of the other nozzles 41C to 41K are omitted.

[Inspection of the state of the first nozzle]
5, in step S04 following the creation of the test chart T, the state of the plurality of first nozzles 41G is determined based on the wetting state of the ink dots Dc of the cyan ink in the test chart T. This determination is made by the user by visually checking the test chart T.

Conventionally, the condition of nozzles that eject gloss ink has been inspected by creating a test chart similar to that for colored inks. According to conventional methods, test charts for inspecting nozzles that eject gloss ink were created by forming only ink dots of gloss ink on a recording medium. However, because gloss ink is transparent, the test chart had poor visibility, making it difficult to determine the condition of the nozzles from the test chart.

The printer 10 according to this embodiment is configured to create a test chart T using gloss ink and colored ink (steps S01 to S03C) to improve the visibility of the test chart T. Below, we will explain how to check for two abnormalities that occur in the first nozzle 41G: an abnormality where gloss ink is not ejected from the first nozzle 41G (also called "nozzle missing"), and an abnormality where the landing position of the gloss ink is shifted (also called "flight deflection"), as examples.

Figure 7 is a schematic vertical cross-sectional view of test chart T. The left-right direction in Figure 7 is the sub-scanning direction X. The gloss ink ink dots Dg form rows extending in the main scanning direction Y (perpendicular to the paper surface in Figure 7). In Figure 7, row Cg1 of gloss ink ink dots Dg indicates a row of normal gloss ink ink dots Dg. Row Cg3 of gloss ink ink dots Dg indicates a row of gloss ink ink dots Dg in the case of nozzle missing. In the case of nozzle missing, gloss ink dots Dg do not exist because gloss ink is not ejected. Therefore, row Cg3 of gloss ink ink dots Dg in the case of nozzle missing is represented by a two-dot chain line. Row Cg5 of gloss ink ink dots Dg indicates a row of gloss ink ink dots Dg in the case of flight curvature. As shown in FIG. 7, the row Cg5 of gloss ink dots Dg is closer to the adjacent row Cg6 of gloss ink dots Dg than in the normal case.

As shown in Figure 7, a cyan ink dot Dc1 that lands between a row Cg1 of ink dots Dg of normal gloss ink and the adjacent row Cg2 of ink dots Dg wets and spreads between the rows Cg1 and Cg2 of ink dots Dg. This is the normal wetting state of cyan ink.

On the other hand, as shown in FIG. 7, the cyan ink ink dot Dc2 that lands between the row Cg3 (not present) of the gloss ink ink dot Dg in the case of a nozzle missing and the adjacent row Cg4 of the ink dot Dg is not prevented from spreading because the row Cg3 of the ink dot Dg does not exist. Therefore, the cyan ink ink dot Dc2 becomes larger than usual. FIG. 8 is a plan view showing a row of cyan ink ink dots Dc that land nearby when the gloss ink lands normally, when the gloss ink misses the nozzle, and when the gloss ink exhibits flight curvature. As shown in FIG. 8, the cyan ink ink dots Dc are lined up in the main scanning direction Y, so they appear as a band extending in the main scanning direction Y. Therefore, when the gloss ink misses the nozzle, the row Cc2 of the cyan ink ink dots Dc2 in the vicinity is wider in the sub-scanning direction X than the row Cc1 of the cyan ink ink dots Dc1 when the gloss ink lands normally. This allows you to confirm that the first nozzle 41G in the corresponding location is missing. Because cyan ink is colored, it is easy to visually confirm the width of the row of ink dots Dc in the sub-scanning direction X.

Furthermore, as shown in FIG. 7, when flight deflection occurs, the cyan ink dot Dc3 that lands between the row Cg5 of gloss ink dots Dg and the adjacent row Cg6 of ink dots Dg is smaller than normal because the distance between rows Cg5 and Cg6 is narrower than normal. Therefore, as shown in FIG. 8, when gloss ink flight deflection occurs, the row Cc3 of cyan ink dots Dc nearby will be narrower in width in the sub-scanning direction X than the row Cc1 of cyan ink dots Dc1 when gloss ink lands normally. This makes it easy to confirm that the first nozzle 41G in the relevant location is flight deflected.

In this way, in the test chart T created by the printer 10 according to this embodiment, if there is an abnormality in the first nozzle 41G that ejects the gloss ink, causing the gloss ink to not be ejected or to deviate from the landing position, the wetting state of the cyan ink will change compared to when the gloss ink is ejected normally. Therefore, by inspecting the wetting state of the cyan ink, it is possible to inspect the state of the first nozzle 41G that ejects the transparent gloss ink. This improves the visibility of the test chart T. According to this method of inspecting the nozzle state, it is possible to easily inspect the state of the first nozzle 41G that ejects the transparent gloss ink.

Specifically, the printer 10 controls the bed moving device 25 to position the recording medium 5 so that the landing position of the cyan ink is close to the landing position of the gloss ink in the sub-scanning direction X, and then ejects the cyan ink from the multiple second nozzles 41C. In other words, the printer 10 deposits the cyan ink at a position slightly offset from the landing position of the gloss ink in the sub-scanning direction X. By overlapping the gloss ink and colored inks in this way, a test chart T with excellent visibility can be created.

More specifically, the printer 10 controls the bed moving device 25 to position the recording medium 5 so that the landing positions of the gloss ink and the cyan ink alternate in the sub-scanning direction X. As a result, the cyan ink dots Dc land near the multiple gloss ink dots Dg aligned in the sub-scanning direction X. Therefore, with this configuration, all or most of the multiple first nozzles 41G aligned in the sub-scanning direction X can be inspected using a single test chart T. This control is possible because the pitch of the multiple first nozzles 41G in the first nozzle row 42G and the pitch of the multiple second nozzles 41C in the second nozzle row 42C are the same pitch P.

In this embodiment, the dot diameter of the hardened gloss ink is set to be equal to or greater than half the pitch P of the first nozzle 41G and the second nozzle 41C, but less than the pitch P. Therefore, if the first nozzle 41G is normal, the hardened ink dots Dg of the gloss ink are arranged with a gap narrower than half the pitch P in the sub-scanning direction X, as shown in FIG. 6. By setting the gap between the hardened ink dots Dg of the gloss ink in this way, the cyan ink dots Dc form sharp, thin bands extending in the main scanning direction Y. Therefore, when the width of the cyan ink dots Dc in the sub-scanning direction X is abnormal, it becomes easier to identify the abnormality. Furthermore, in the case of flight curvature, the accuracy of detecting the abnormality is improved.

The printer 10 according to this embodiment is configured to eject gloss ink and cyan ink onto the recording medium 5 while moving the recording head 40 in the main scanning direction Y. With this configuration, the cyan ink dots Dc appear as bands extending in the main scanning direction Y, further improving the visibility of the test chart T.

This method is particularly suitable when the transparent ink and the colored ink are photocurable inks. The ink dots Dg of the photocurable gloss ink are formed to rise on the recording medium 5 with a predetermined gap therebetween, so the way the cyan ink that lands nearby spreads varies depending on the position where the gloss ink dots Dg are formed. Therefore, the appearance of the test chart T is likely to differ between when the first nozzle 41G is normal and when it is abnormal. In addition, if the gloss ink is photocurable ink, the dot diameter of the gloss ink dots Dg can be easily adjusted by adjusting the ejection amount and the timing of light irradiation. As for the colored ink, it is preferable that the ink is photocurable ink because the time from ejection to curing can be easily controlled. By stabilizing the time from ejection to curing of the colored ink, the conditions for the colored ink to spread can be stabilized, and the reliability of the judgment in step S04 is improved.

A preferred embodiment has been described above. However, the above embodiment is merely an example, and the technology disclosed herein can be implemented in various other forms. For example, in the above embodiment, the first nozzle row 42G that ejects gloss ink and the second nozzle row 42C to the fifth nozzle row 42K that eject colored inks are staggered, but the positions of both in the sub-scanning direction X may be aligned. The landing positions of the transparent ink and the landing positions of the colored inks on the test chart may be shifted by controlling a moving device in the sub-scanning direction. In addition, it is not necessary for all the first nozzles to eject transparent ink at once, and the transparent ink may be ejected from some of the first nozzles at once. Similarly, it is not necessary for all the second nozzles to eject colored ink at once, and the colored ink may be ejected from some of the second nozzles at once.

The ink applicable to the technology disclosed herein is not limited to photocurable ink. The ink may be, for example, a thermosetting ink such as latex ink. It may also be a thermally drying ink such as water-based latex ink or solvent ink. In the case of a thermosetting ink or a solvent ink in which the solvent evaporates when heated, the ink can be cured by heating or drying the ink. In addition, the dot diameter of the transparent ink after curing is not limited to the above.

In the above embodiment, the printer 10 was configured to eject gloss ink and cyan ink onto the recording medium 5 while moving the recording head 40 in the main scanning direction Y. However, the ejection of gloss ink and colored ink onto the recording medium 5 may be performed without moving the recording head 40 in the main scanning direction Y.

Unless otherwise specified, the configuration of the inkjet printer is not limited. For example, the technology disclosed herein can be used for roll-to-roll type inkjet printers. The technology disclosed herein can also be used for devices that incorporate an inkjet printer as part of the device, such as an inkjet printer with a cutting head.

5 Recording medium 10 Printer 20 Flatbed (support table)
25X Sub-scanning direction movement mechanism (first movement device)
35 Carriage moving device (second moving device)
40 Recording head 41G First nozzle 41C Second nozzle 42G First nozzle row 42C Second nozzle row 50 Light irradiation device 100 Control device 110 Mode selection unit 130 Test chart creation unit 131 First creation unit 132 Second creation unit 133 First hardening processing unit 134 Second hardening processing unit 135 Dot control unit T Test chart

Claims (12)

1. A method for inspecting a state of a plurality of first nozzles in an inkjet printer having a recording head having a plurality of first nozzles that eject a first transparent ink and a plurality of second nozzles that eject a second colored ink, comprising:
a first step of driving the inkjet printer to eject the first ink from the first nozzles toward a recording medium and cause the first ink to land on the recording medium;
a second step of curing the first ink that has landed on the recording medium after the first step;
a third step of driving the inkjet printer after the second step to eject the second ink from the second nozzles toward the recording medium and to land the second ink between the landing positions of the first ink; and
and a fourth step of determining a state of the plurality of first nozzles based on a wetting state of the ink dots of the second ink in the test chart.
A method for inspecting the nozzle condition of an inkjet printer. the first nozzles and the second nozzles are aligned in a first direction to form a first nozzle row and a second nozzle row, respectively;
In the first step, the first ink is caused to land on the recording medium while the recording head is moved in a second direction perpendicular to the first direction relative to the recording medium;
In the third step, the second ink is deposited between the deposition positions of the first ink in the first direction while the recording head is moved in the second direction relative to the recording medium.
2. The method for inspecting the state of nozzles in an inkjet printer according to claim 1. a landing position of the first ink and a landing position of the second ink alternate with each other in the first direction;
3. The method for inspecting the state of nozzles in an inkjet printer according to claim 2. a pitch of the first nozzles in the first nozzle row and a pitch of the second nozzles in the second nozzle row are a first pitch,
a dot diameter of the first ink after curing is equal to or greater than half of the first pitch and less than the first pitch;
4. The method for inspecting the state of nozzles in an inkjet printer according to claim 3. the second ink is a photocurable ink,
the forming step of the test chart further includes a step of curing the second ink by irradiating the second ink that has landed on the recording medium with light for curing the second ink, after the third step and before the fourth step.
5. The method for inspecting the state of nozzles in an inkjet printer according to claim 1. the first ink is a photocurable ink,
In the second step, the first ink that has landed on the recording medium is irradiated with light that cures the first ink, thereby curing the first ink.
6. The method for inspecting the state of nozzles in an inkjet printer according to claim 1. A support base for supporting a recording medium;
a recording head having a plurality of first nozzles that eject a transparent first ink toward the recording medium on the support table, and a plurality of second nozzles that eject a colored second ink toward the recording medium on the support table;
A control device,
The control device includes:
a mode selection unit configured to be able to select a mode for creating a test chart for inspecting a state of the plurality of first nozzles;
a test chart creating unit that creates the test chart on the recording medium in response to a selection made by the mode selecting unit,
The test chart creation unit includes:
a first production unit that ejects the first ink from the plurality of first nozzles toward the recording medium and causes the first ink to land on the recording medium;
a second creation unit that ejects the second ink from the second nozzles toward the recording medium after the first ink that has landed on the recording medium has hardened, and causes the second ink to land between landing positions of the first ink,
Inkjet printer. the plurality of first nozzles are aligned in a first direction to form a first nozzle row;
the plurality of second nozzles are aligned in the first direction to form a second nozzle row,
a first moving device that moves at least one of the recording head and the recording medium on the support table to move the recording medium in the first direction relative to the recording head;
the second creation unit controls the first moving device to position the recording medium at a position such that a landing position of the second ink is between landing positions of the first ink in the first direction, and then causes the second ink to be ejected from the plurality of second nozzles.
8. The inkjet printer according to claim 7. a pitch of the first nozzles in the first nozzle row and a pitch of the second nozzles in the second nozzle row are the same pitch,
the second creation unit controls the first moving device to position the recording medium at a position where a landing position of the first ink and a landing position of the second ink alternate with each other in the first direction;
9. The inkjet printer according to claim 8. a dot diameter of the first ink after curing is equal to or greater than half the pitch of the first nozzles and the second nozzles and is less than the pitch of the first nozzles and the second nozzles;
10. The inkjet printer according to claim 9. a second moving device that moves at least one of the recording head and the recording medium on the support table, thereby moving the recording head in a second direction perpendicular to the first direction with respect to the recording medium,
the first creation unit controls the second moving device to move the recording head in the second direction relative to the recording medium, while causing the first ink to land on the recording medium;
the second production unit controls the second moving device to move the recording head in the second direction relative to the recording medium, while discharging the second ink from the plurality of second nozzles;
The inkjet printer according to any one of claims 8 to 10. the first ink and the second ink are photocurable inks,
a light irradiation device that irradiates the recording medium on the support table with light that cures the first ink and the second ink,
The test chart creation unit includes:
a first curing processing unit that controls the light irradiation device to irradiate the first ink on the recording medium with light after the first ink is discharged by the first preparation unit and before the second ink is discharged by the second preparation unit, thereby curing the first ink on the recording medium;
a second curing processing unit that controls the light irradiation device to irradiate the second ink on the recording medium with light after the second ink is ejected by the second preparation unit, and cures the second ink on the recording medium.
The inkjet printer according to any one of claims 7 to 11.

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