JP7539232B2 - Inkjet printers and how to check light intensity - Google Patents

Description

The present invention relates to an inkjet printer equipped with a light irradiation device and a method for checking the intensity of light emitted by the inkjet printer.

Conventionally, printers equipped with an ink head that ejects photocurable ink onto a recording medium and a light irradiation device that emits light to cure the ink have been known. For example, Patent Document 1 discloses an inkjet printer equipped with an ejection head that ejects photocurable color ink, white ink, and clear ink, and an ultraviolet lamp that cures the photocurable ink.

JP 2018-69707 A

The intensity of light emitted by the light irradiation device may change, for example, due to aging. In addition, the intensity of light emitted by the light irradiation device may partially decrease due to dirt on the light irradiation device or deterioration in the performance of some light sources. The degree of change in light intensity due to aging or partial change in light intensity is not easily predictable. If the intensity of light emitted by the light irradiation device varies or changes, this will cause variation or change in print quality. For this reason, you may want to check whether the intensity of light emitted by the light irradiation device is within the desired range.

The present invention has been made in consideration of the above points, and its purpose is to provide an inkjet printer that can check whether the intensity of light emitted by a light irradiation device is within a desired range. It is also to provide a method for checking whether the intensity of light emitted by a light irradiation device is within a desired range.

The inkjet printer disclosed herein includes a support table for supporting a recording medium or a test piece, an ink head for ejecting a photocurable ink toward the support table, a light irradiation device for irradiating the support table with light for curing the ink, a detection device for detecting the state of the test piece placed on the support table, and a control device. The test piece is configured such that, when placed on the support table and irradiated with light by the light irradiation device, the state of the test piece changes according to the intensity of the irradiated light.
The control device includes a reference data storage unit, an irradiation control unit, a detection control unit, a data acquisition unit, a comparison unit, a threshold storage unit, and a judgment unit. The reference data storage unit stores reference data related to the state of the test piece. The irradiation control unit controls the light irradiation device to irradiate the light toward the support base. The detection control unit controls the detection device to detect the state of the test piece after it is placed on the support base and irradiated with the light. The data acquisition unit acquires detection data related to the state of the test piece detected by the detection device. The comparison unit is configured to determine the difference between the reference data and the detection data. The threshold storage unit stores a threshold related to the difference between the reference data and the detection data. The judgment unit judges whether the difference between the reference data and the detection data determined by the comparison unit exceeds the threshold.

The light intensity confirmation method disclosed herein is a method for confirming the intensity of light irradiated by the light irradiation device in an inkjet printer equipped with a support table for supporting a recording medium, an ink head for ejecting photocurable ink toward the support table, and a light irradiation device for irradiating the support table with light for curing the ink. This light intensity confirmation method includes the steps of placing a test piece on the support table, the state of which changes depending on the intensity of the light irradiated by the light irradiation device, irradiating the light toward the test piece on the support table with the light irradiation device, detecting the state of the test piece after it is placed on the support table and irradiated with the light by a detection device that detects the state of the test piece, and acquiring detection data, determining the difference between the detection data and previously acquired reference data, which is data regarding the state of the test piece, and judging whether the difference between the reference data and the detection data exceeds a predetermined threshold.

The inkjet printer and the method for checking the light intensity described above detect the state of the test piece, which changes depending on the intensity of the received light, and by comparing the detection result with previously acquired reference data, it is possible to check whether the intensity of the light irradiated by the light irradiation device is within the desired range.

1 is a perspective view showing a printer according to an embodiment; FIG. 2 is a front view showing the printer with the front cover open. FIG. 4 is a plan view showing the lower surface of the carriage. FIG. 2 is a block diagram of a printer. 10 is a flowchart showing a flow of light intensity correction. FIG. 2 is a plan view illustrating a test piece. FIG. 11 is a block diagram of a printer according to a first modified example. FIG. 11 is a block diagram of a printer according to a second modified example. FIG. 13 is a block diagram of a printer according to a third modified example. FIG. 11 is a plan view illustrating a test piece according to a second embodiment.

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.

First Embodiment
FIG. 1 is a perspective view showing 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 has an internal space provided with 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, a detection device 60, and a control device 100 (see FIG. 1).

The flatbed 20 is a support platform that supports the recording medium 5. When the test piece 200 (see FIG. 6) described later is placed on the flatbed 20, the flatbed 20 is a support platform that supports the test piece 200. The printer 10 according to this embodiment is a so-called flatbed type printer. The flatbed 20 is a flat member. The flatbed 20 extends in the main scanning direction Y and the sub-scanning direction X. The flatbed 20 faces the up-down direction Z. The recording medium 5 or the test piece 200 is placed on the upper surface of the flatbed 20. The shape of the recording medium 5 is not particularly limited, and may have various three-dimensional shapes in addition to a flat plate shape. The material of the recording medium 5 is also not particularly limited, and the recording medium 5 may be, for example, wood, metal, glass, paper, cloth, etc. The flatbed 20 is disposed approximately in the center of the main scanning direction Y in the internal space of the case 11.

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. However, the configuration of the bed moving device 25 is not limited. For example, the vertical positional relationship between the sub-scanning direction moving mechanism 25X and the vertical direction moving mechanism 25Z may be reversed.

The carriage 30 is equipped with a recording head 40, a light irradiation device 50, and a detection device 60. The carriage 30 is arranged to face the flatbed 20. The carriage 30 is disposed above the flatbed 20. The carriage 30 is moved in the main scanning direction Y by a carriage moving device 35. 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.

The bed moving device 25 and the carriage moving device 35 constitute a moving mechanism that changes the positional relationship between the recording head 40 and the flatbed 20. In this embodiment, the moving device also changes the positional relationship between the flatbed 20 and the detection device 60. As described later, the detection device 60 is provided on the carriage 30 and moves together with the carriage 30. In this embodiment, the moving device is configured to move the flatbed 20 in the sub-scanning direction X and the vertical direction Z, and to move the recording head 40 and the detection device 60 in the main scanning direction Y, but is not limited to this. The moving device is not limited any further as long as it is configured to change the positional relationship between the flatbed 20 and the mounted items of the carriage 30 (the recording head 40, the light irradiation device 50, and the detection device 60) by moving at least one of them. For example, the moving mechanism may be configured so that one of the flatbed 20 and the carriage 30 moves in the main scanning direction Y, the sub-scanning direction X, and the vertical direction Z, and the other is stationary.

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 flat bed 20. The recording head 40 includes a first ink head 41, a second ink head 42, and a third ink head 43. The first ink head 41, the second ink head 42, and the third ink head 43 are each configured to eject ink toward the flat bed 20.

As shown in FIG. 3, the first ink head 41 to the third ink head 43 all extend in the sub-scanning direction X. The first ink head 41 and the second ink head 42 are arranged at the same position in the sub-scanning direction X. The first ink head 41 and the second ink head 42 are arranged side by side in the main scanning direction Y. The third ink head 43 is arranged at a position shifted from the first ink head 41 and the second ink head 42 in the sub-scanning direction X. More specifically, the third ink head 43 is arranged at a position shifted backward from the first ink head 41 and the second ink head 42. However, the third ink head 43 is not completely shifted from the first ink head 41 and the second ink head 42 in the sub-scanning direction X, and is partially overlapped. Note that the number of ink heads provided in the recording head 40 is three here, but the number of ink heads is not limited.

The first ink head 41, the second ink head 42, and the third ink head 43 each have a plurality of nozzles 41a, 42a, and 43a aligned in the sub-scanning direction X. The nozzles 41a, 42a, and 43a are minute holes from which ink is ejected. The nozzles 41a to 43a each communicate with a pressure chamber in which ink is stored. Ink is ejected from the nozzles 41a to 43a by the expansion/contraction of the pressure chamber, for example, by driving a piezoelectric element or the like. The nozzles 41a to 43a are each formed to face the flatbed 20. The first ink head 41 to the third ink head 43 of the recording head 40 each have a nozzle row in which a plurality of nozzles are aligned in the sub-scanning direction X. For example, in the first ink head 41, the plurality of nozzles 41a form two nozzle rows 41b and 41c. Both nozzle rows 41b and 41c extend in the sub-scanning direction X. The nozzle rows 41b and 41c are arranged side by side in the main scanning direction Y. In the second ink head 42, the nozzles 42a also form two nozzle rows that extend in the sub-scanning direction X and are arranged side by side in the main scanning direction Y. In the third ink head 43, the nozzles 43a also form two nozzle rows that extend in the sub-scanning direction X and are arranged side by side in the main scanning direction Y. Here, the number of nozzle rows in one ink head is two rows, but it may be one row, or three or more rows. In addition, in FIG. 3, the number of nozzles that form one nozzle row is illustrated as 10, but in reality, many more (for example, 300) are formed. The number of nozzles that form one nozzle row is not limited.

The first ink head 41 to the third ink head 43 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 46. In this embodiment, the ink cartridge housing 46 is provided at the left rear of the case 11. Different ink cartridges 45 are connected to the multiple nozzle rows of the first ink head 41 to the third ink head 43. Here, ink cartridges 45 that store one of the four process color inks of CMYK are connected to the four nozzle rows of the first ink head 41 and the second ink head 42. One of the four process color inks of CMYK is ejected from the nozzles of the four nozzle rows of the first ink head 41 and the second ink head 42. In addition, ink cartridges 45 that store two special color inks, white and clear, are connected to the two nozzle rows of the third ink head 43. The nozzles in the two nozzle rows of the third ink head 43 eject white and clear spot color inks, respectively. However, the colors of ink ejected from the nozzles in each nozzle row of the first ink head 41 to the third ink head 43 are not limited.

In this embodiment, all of the inks ejected from the first ink head 41 to the third ink head 43 are photocurable inks. Here, the photocurable inks are ultraviolet-curable inks that cure when irradiated with ultraviolet light. There are no particular limitations on the components, characteristics, etc. of the photocurable inks.

The light irradiation device 50 is fixed to 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 the flatbed 20 with light that cures the photocurable ink. 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.

The detection device 60 detects the state of the test piece 200 placed on the flatbed 20. In this embodiment, the test piece 200 is a test pattern 210 (see FIG. 6) formed on the recording medium 5 by ejecting ink. The test piece 200 is configured such that when placed on the flatbed 20 and irradiated with light by the light irradiation device 50, the state of the test piece 200 changes according to the intensity of the irradiated light. More specifically, when light is irradiated by the light irradiation device 50, the density of the test pattern 210 changes according to the intensity of the irradiated light. Details of the test piece 200 will be described later. In this embodiment, the detection device 60 includes a densitometer 60A capable of measuring the density of the test pattern 210. The detection device 60 is provided on the carriage 30 and faces the flatbed 20.

Here, the detection device 60 is provided on the carriage 30, but it may be provided at another position where it can detect the state of the test piece 200 on the flatbed 20. For example, the detection device 60 may be provided on the inner surface of the front cover 12 (the surface that faces the internal space of the printer 10 when the front cover 12 is closed), etc.

Figure 4 is a block diagram of the printer 10. 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 first ink head 41 to the third ink head 43, the light source 51 of the light irradiation device 50, and the densitometer 60A of the detection device 60, and controls their operations. The control device 100 is, for example, a computer connected to the printer 10, and may include a central processing unit (hereinafter referred to as CPU), a ROM in which programs executed by the CPU are stored, and a RAM. Each part of the control device 100 may be configured by software or hardware. Each part may be a processor or a circuit. The configuration of the control device 100 is not particularly limited. As shown in FIG. 4, the control device 100 includes a discharge control unit 101, an irradiation control unit 102, a detection control unit 103, a movement control unit 104, a data acquisition unit 105, a reference data storage unit 106, a threshold storage unit 107, a comparison unit 108, a determination unit 109, a warning unit 110, and a correction unit 111. These control units control the operation of the printer 10 to check whether the light irradiation device 50 is emitting light with an intensity within a desired range. The control device 100 may include other control units, such as a control unit that controls the printing operation, but the description and illustration are omitted here.

The ejection control unit 101 forms the test piece 200 by controlling the first ink head 41 to the third ink head 43 to eject ink onto the recording medium 5. The irradiation control unit 102 controls the light irradiation device 50 to irradiate light toward the flatbed 20. At this time, the test piece 200 formed by the ejection control unit 101 is placed on the flatbed 20. The test piece 200 is then irradiated with light from the light irradiation device 50. When the intensity of the light irradiated by the light irradiation device 50 changes, the density of the test pattern 210 on the test piece 200 changes. The printer 10 uses this to check whether the light irradiation device 50 is irradiating light with an intensity within the desired range.

The "intensity" of the light irradiated by the light irradiation device 50 can be defined in various ways. For example, the intensity of light can be defined by the irradiance of the light (the energy of light irradiated to a unit area per unit time). Alternatively, the intensity of light can be defined by the radiance or radiant intensity of the light. However, as described in detail below, in this embodiment, whether the light irradiation device 50 is irradiating light of the desired intensity is confirmed by the difference between the reference data and the detection data regarding the test pattern 200. Therefore, as long as the reference data and the detection data are obtained by the same method, the "intensity" of light may be defined in any of various known ways.

The detection control unit 103 controls the detection device 60 to detect the state of the test piece 200 after it is placed on the flatbed 20 and irradiated with light. Here, the detection control unit 103 controls the detection device 60 to detect the density of the test pattern 210 after it is placed on the flatbed 20 and irradiated with light (hereinafter, also referred to as the detected density D1, see FIG. 5). The movement control unit 104 controls the movement device (bed movement device 25 and carriage movement device 35) to move the detection point of the detection device 60 on the flatbed 20. This allows the printer 10 to check at multiple points on the flatbed 20 whether the light irradiation device 50 is irradiating light with an intensity within the desired range. The data acquisition unit 105 acquires detection data regarding the state of the test piece 200 detected by the detection device 60.

The reference data storage unit 106 stores reference data regarding the state of the test piece 200. The reference data stored in the reference data storage unit 106 is, for example, a suitable light intensity previously confirmed in one machine. The suitable light intensity is determined, for example, by checking the print quality of the printout. However, the above-mentioned method of setting the reference data is merely an example, and other methods may be used. For example, the reference data may be determined based on the design specifications of the light irradiation device 50. Hereinafter, the reference data is the density of the test pattern 210 formed on the test piece 200. Hereinafter, this reference density is also referred to as the reference density Dr (see FIG. 5). The threshold value storage unit 107 stores a threshold value ΔDr (see FIG. 5) regarding the difference between the reference data stored in the reference data storage unit 106 and the detection data acquired by the data acquisition unit 105. The method of determining this threshold value ΔDr is not limited, and may be determined, for example, by checking the print quality of the printout.

The comparison unit 108 is configured to determine the difference between the reference data stored in the reference data storage unit 106 and the detection data acquired by the data acquisition unit 105. Here, the comparison unit 108 calculates the difference ΔD (see FIG. 5) between the reference density Dr of the test pattern 210 stored in the reference data storage unit 106 and the detection density D1 of the test pattern 210 acquired by the data acquisition unit 105. The determination unit 109 determines whether the difference between the reference data and the detection data obtained by the comparison unit 108 exceeds the threshold value stored in the threshold value storage unit 107.

The warning unit 110 issues a warning when the judgment unit 109 judges that the difference between the reference data and the detection data exceeds a threshold value. The correction unit 111 corrects the output of the light irradiation device 50 based on the difference between the reference data and the detection data obtained by the comparison unit 108. The correction unit 111 may, for example, classify the difference between the reference data and the detection data into a plurality of ranks and correct the output of the light irradiation device 50 by an amount of correction corresponding to the rank. The printer 10 may then detect the intensity of the light emitted by the light irradiation device 50 again to confirm the correction result. However, the method by which the correction unit 111 corrects the output of the light irradiation device 50 is not particularly limited. Furthermore, the warning method is not particularly limited.

The process of light intensity correction by the printer 10 is described below. The intensity of the light emitted by the light irradiation device 50 may change, for example, due to aging. In addition, the intensity of the light emitted by the light irradiation device 50 may partially decrease due to dirt on the irradiation port 52 of the light irradiation device 50 or performance degradation of some of the light sources 51. The degree of change in light intensity due to aging or partial change in light intensity is not easily predictable. If the intensity of the light emitted by the light irradiation device 50 varies or changes, the print quality will vary or change. For this reason, it is desirable to appropriately measure the intensity of the light emitted by the light irradiation device 50 and check whether the light intensity is within the desired range.

Figure 5 is a flowchart showing the flow of light intensity correction according to this embodiment. As shown in Figure 5, in correcting the intensity of light from the light irradiation device 50, a test piece 200 is formed in step S01. Figure 6 is a plan view showing a schematic of the test piece 200. As shown in Figure 6, in this embodiment, the test piece 200 is a test pattern 210 printed on a recording medium 5.

As shown in FIG. 6, the test pattern 210 has multiple regions 211 to 220, each of which has a different ink ejection density. The first region 211 to the tenth region 220 are each configured in a rectangular shape. The first region 211 to the tenth region 220 are spaced apart from one another. The first region 211 to the tenth region 220 are arranged side by side in the sub-scanning direction X. The first region 211 to the tenth region 220 are arranged in this order from front to rear in the sub-scanning direction X.

The first area 211 to the tenth area 220 are each formed by ink dots of black ink. The first area 211 to the tenth area 220 are each solidly painted with black ink. The first area 211 to the tenth area 220 are printed with different ejection densities. The ejection density here means the number of ink dots per predetermined area. The ejection density is expressed as a percentage (%) of the maximum number of ink dots per predetermined area. In this embodiment, the first area 211 is printed with an ejection density of 10% of the maximum number of ink dots per predetermined area. The second area 212 is printed with an ejection density of 20% of the maximum number of ink dots per predetermined area. The test pattern 210 is configured such that the ejection density increases by 10% for each of the third area 213, the fourth area 214, and so on. The ejection density of the tenth area 220 is 100%.

In step S02, the test piece 200 is irradiated with light from the light irradiation device 50. This causes the ink dots constituting the test pattern 210 to harden. In FIG. 5, step S02 is shown to be performed after step S01 is completed, but this is for convenience of illustration, and in reality, steps S01 and S02 may be performed in parallel with a time lag. For example, according to one preferred method, the printer 10 prints the first region 211 on the recording medium 5 by ejecting ink from the recording head 40 while moving the carriage 30 to the right in the main scanning direction Y. At this time, the light irradiation device 50, which is provided behind the recording head 40 in the traveling direction of the carriage 30 (to the left of the printer 10), irradiates light to the ink that has landed on the recording medium 5. This hardens the ink in the first region 211. After that, the printer 10 moves the flatbed 20 forward. With the flatbed 20 fixed in this position, the printer 10 ejects ink from the recording head 40 while moving the carriage 30 to the right in the main scanning direction Y. This causes the second region 212 to be printed behind the first region 211. At this time, the light irradiation device 50 irradiates the ink in the second region 212 with light. This hardens the ink in the second region 212. The same process is repeated up to the tenth region 220.

The above-mentioned method is merely one suitable example, and steps S01 and S02 may be performed in other ways. For example, the printer 10 may print when the carriage 30 moves to the right, and harden the ink when the carriage 30 moves to the left. The method for forming and hardening the test piece 200 is not particularly limited.

Here, if the light intensity in step S02 changes, the density of the test pattern 210 changes. Specifically, for example, if the light becomes weaker, the density of the test pattern 210 becomes higher. This is because, as the light becomes weaker, the ink hardens more slowly, causing the ink dots to flatten accordingly. When the ink dots flatten, the light reflection becomes closer to regular reflection, and less light is reflected to the sensor of the densitometer 60A. As a result, the density of the test pattern 210 becomes higher. Conversely, if the light becomes stronger, the surface of the ink dots becomes more microscopically uneven, and the density of the test pattern 210 becomes lower. Therefore, it is possible to check whether the light irradiation device 50 is irradiating light with an intensity within the desired range by the density of the test pattern 210.

In the next step S03, the density D1 of the test pattern 210 is detected by the detection device 60. At this time, the detection device 60 is moved in the main scanning direction Y together with the carriage 30, and the test piece 200 is moved in the main scanning direction Y together with the flatbed 20. This makes it possible to check at multiple points on the flatbed 20 whether the light irradiation device 50 is irradiating light with an intensity within the desired range. Preferably, the density at all points on the test pattern 210 is detected by detecting the density at the multiple points.

In step S04, the difference ΔD between a predetermined reference density Dr of the test pattern 210 and the detected density D1 of the test pattern 210 detected by the detection device 60 is calculated. Here, the difference in density is calculated for each of the multiple detection points.

In step S05, the difference ΔD between the reference density Dr and the detected density D1 of the test pattern 210 is compared with a predetermined threshold value ΔDr. The threshold value ΔDr is set for each of the first area 211 to the tenth area 220. This makes it possible to more precisely check whether the light intensity is at a problem-free level according to the ink ejection density. If the difference ΔD between the reference density Dr and the detected density D1 of the test pattern 210 is greater than the threshold value ΔDr (if the result of step S05 is "NO"), a warning is issued in step S07. Furthermore, in the following step S08, the output of the light source 51 is corrected. The output of the light source 51 is corrected, for example, by correcting the current value passed through the light source 51. If the difference ΔD between the reference density Dr and the detected density D1 of the test pattern 210 is equal to or less than the threshold value ΔDr (if the result of step S05 is "YES"), a message is displayed in step S06 indicating that the light intensity is normal.

In this embodiment, if the result of step S05 is "NO", a warning is issued and correction is performed, but only a warning may be issued. Alternatively, no warning may be issued and only correction may be performed.

In this way, the test piece 200 according to this embodiment is configured so that its state changes depending on the intensity of the irradiated light when irradiated by the light irradiation device 50, and the printer 10 according to this embodiment is configured to irradiate the test piece 200 with light from the light irradiation device 50. The printer 10 further detects the state of the test piece 200 after light is irradiated, obtains detection data, and determines whether the difference between predetermined reference data and the detection data exceeds a predetermined threshold value. This makes it possible to check whether the intensity of the light irradiated by the light irradiation device 50 is within a desired range.

Conventional inkjet printers do not have a component for detecting the intensity of light from the light irradiation device as described above, so the intensity of light irradiated by the light irradiation device is measured using, for example, an actinometer. However, the actinometer needs to be installed precisely to ensure the reproducibility of the measurements, which is time-consuming.

Furthermore, there were space limitations because the light meter had to be installed opposite the light irradiation port of the light irradiation device. Also, to measure the amount of light in the entire irradiation range, the light amount had to be measured at multiple points, and since it was necessary to set up a light meter every time the measurement point was moved, the time required for measurement was extremely long.

In contrast, in this embodiment, the printer 10 detects the state of the test piece 200, whose state changes depending on the intensity of the irradiated light, and compares it with predetermined reference data. This method is simpler than, for example, a method of measuring the light intensity with an actinometer. Furthermore, when measuring the light intensity with an actinometer, considerable care must be taken to ensure the reproducibility of the measurement, and if the measurement reproducibility is poor, the feedback results of the output of the light irradiation device cannot be guaranteed. However, in this embodiment, since it is the state of the test piece 200 that is directly detected, stable feedback is possible.

Here, the test piece 200 has a test pattern 210 formed by ejecting ink onto the recording medium 5, and the detection device 60 is equipped with a densitometer 60A capable of measuring the density of the test pattern 210. The printer 10 stores reference data regarding the density of the test pattern 210. Although the physical quantity that serves as an index of light intensity is not limited to the density of the test pattern 210, this configuration is particularly effective when it is desired to suppress variations or changes in image density due to variations or changes in light intensity. The densitometer 60A can also be used, for example, for color calibration of the printer 10. Therefore, color calibration can be performed without adding any components.

In this embodiment, the test pattern 210 of the test piece 200 has multiple regions 211-220, each with a different ink ejection density. This configuration of the test pattern 210 makes it possible to more precisely check whether the light intensity is at an acceptable level depending on the ink ejection density. However, the test pattern 210 formed on the test piece 200 is not limited to this test pattern.

In this embodiment, the printer 10 is configured to issue a warning when it is determined that the difference ΔD between the reference data (reference density Dr) and the detection data (detection density D1) exceeds the threshold value ΔDr. With this configuration, the user can know that the intensity of the light irradiated by the light irradiation device 50 is outside the desired range. In addition, the printer 10 is configured to correct the output of the light irradiation device 50 based on the difference ΔD between the reference data (reference density Dr) and the detection data (detection density D1). With this configuration, the intensity of the light irradiated by the light irradiation device 50 can be automatically corrected to fall within the desired intensity.

The printer 10 according to this embodiment is further equipped with a moving device that changes the positional relationship between the flatbed 20 and the detection device 60 by moving the flatbed 20 and the detection device 60, and is configured to be able to move the detection point of the detection device 60 on the flatbed 20. The moving devices are a bed moving device 25 and a carriage moving device 35 in this embodiment. With this configuration, it is possible to check at multiple points on the flatbed 20 whether the light irradiation device 50 is irradiating light with an intensity within a desired range. Therefore, partial abnormalities in the light intensity can be found. Also, the time required for the work can be shortened compared to, for example, a method of measuring the light intensity while changing the installation location of a light meter.

(Modification of the first embodiment)
In the first embodiment, the intensity of the light emitted by the light irradiation device 50 is detected using the density of the test pattern 210 as an index, but other physical quantities may be used as an index. The following describes the configuration of the printer 10 when a physical quantity other than density is used as an index.

(First Modification)
In the first modified example, the gloss of the surface of the test pattern 210 is detected. In the test piece 200 according to this modified example, the test pattern 210 is formed by ejecting ink onto the recording medium 5, more specifically, the test pattern 210 is formed by ejecting clear ink onto the recording medium 5. The shape of the test pattern 210 does not have to be the same as that of the first embodiment, and is not limited thereto. The same applies to the second and third modified examples described below.

Figure 7 is a block diagram of the printer 10 according to the first modified example. The control device 100 includes an ejection control unit 101 that controls the third ink head 43 to eject clear ink onto the recording medium 5 to form the test piece 200. As shown in Figure 7, the detection device 60 includes a gloss meter 60B that can measure the light reflectance of the test pattern 210. The reference data storage unit 106 stores reference data related to the light reflectance of the test pattern 210.

When the intensity of the light irradiated onto the clear ink changes, the gloss of the test pattern 210 changes. Specifically, for example, when the light becomes weaker, the gloss of the test pattern 210 increases. This is because when the light becomes weaker, the ink hardens more slowly, causing the ink dots to flatten accordingly. Conversely, when the light becomes stronger, the gloss of the test pattern 210 decreases. Therefore, it is possible to check whether the light irradiation device 50 is irradiating light with an intensity within the desired range by checking the gloss of the test pattern 210. This modified example is particularly effective when it is desired to suppress variations or changes in the gloss of an image due to variations or changes in the light intensity.

(Second Modification)
In the second modified example, the color value of the test pattern 210 is detected. In the test piece 200 according to this modified example, the test pattern 210 is formed by ejecting ink onto the recording medium 5. The type of ink forming the test pattern 210 is not particularly limited, but is preferably a color ink (here, a mixture of two or more of CMY). More preferably, the ink forming the test pattern 210 is a mixture of two or more of CMY. FIG. 8 is a block diagram of the printer 10 according to the second modified example. The control device 100 includes an ejection control unit 101 that controls the first ink head 41 to the third ink head 43 to eject ink onto the recording medium 5, thereby forming the test piece 200. As shown in FIG. 8, the detection device 60 includes a colorimeter 60C that can measure the color value of the test pattern 210. The reference data storage unit 106 stores reference data regarding the color value of the test pattern 210.

The color value of the test pattern 210 varies depending on the intensity of the light irradiated onto the ink. When the light is weak, ink dots of different colors tend to mix. Therefore, the test pattern 210 when the light is weak shows a different color value than the test pattern 210 when the light is strong and each ink dot is independent. Therefore, it is possible to check whether the light irradiation device 50 is irradiating light with an intensity within a desired range by using the color value of the test pattern 210. This modification is particularly effective when it is desired to suppress color variations or changes in an image caused by variations or changes in the light intensity. The colorimeter 60C can also be used for color calibration of the printer 10. Therefore, color calibration can be performed without adding any components.

(Third Modification)
In the third modified example, the shape of the test pattern 210 is detected. In the test piece 200 according to this modified example, the test pattern 210 is formed by discharging ink onto the recording medium 5. The type of ink forming the test pattern 210 is not particularly limited. FIG. 9 is a block diagram of the printer 10 according to the third modified example. The control device 100 includes a discharge control unit 101 that controls the first ink head 41 to the third ink head 43 to discharge ink onto the recording medium 5, thereby forming the test piece 200. As shown in FIG. 9, the detection device 60 includes a camera 60D that identifies the shape of the test pattern 210 by photographing the test pattern 210. The reference data storage unit 106 stores reference data regarding the shape of the test pattern 210.

When the intensity of the light irradiated to the ink changes, the contour of the test pattern 210 changes. Specifically, for example, when the light becomes weaker, it takes longer for the ink dots to harden, causing the ink dots to wet and spread. Therefore, the contour of the test pattern 210 spreads outward from the test pattern 210 compared to when the light is strong. Therefore, it is possible to check whether the light irradiation device 50 is irradiating light with an intensity within the desired range by checking the shape of the test pattern 210. This modified example is particularly effective when it is desired to suppress variation or change in the shape of an image due to variation or change in the light intensity. The change in the shape of the image changes, for example, the sharpness of the image.

Second Embodiment
In the second embodiment, the intensity of light irradiated by the light irradiation device is confirmed using a test piece whose color density changes depending on the intensity of the irradiated light. The test piece is, for example, photosensitive paper. In the following description of the second embodiment, the same reference numerals are used for the members common to the first embodiment, and the duplicated description is omitted or simplified.

Figure 10 is a plan view that shows a schematic diagram of a test piece 200 according to this embodiment. As shown in Figure 10, the test piece 200 has a plurality of photosensitive regions 230 arranged in a matrix in the main scanning direction Y and the sub-scanning direction X. The color density of the photosensitive regions 230 changes depending on the intensity of the light irradiated. In more detail, the color density of the photosensitive regions 230 increases when the intensity of the light irradiated is strong. Conversely, the color density of the photosensitive regions 230 decreases when the intensity of the light irradiated is weak.

The printer 10 may have a configuration generally similar to that of the first embodiment. The detection device 60 may include a densitometer 60A capable of measuring the color density of the test piece 200, and the reference data storage unit 106 may store reference data relating to the color density of the test piece 200. However, the printer 10 does not need to include a discharge control unit.

In this embodiment, the printer 10 irradiates the test piece 200 placed on the flatbed 20 with light from the light irradiation device 50. This changes the color density of the photosensitive area 230. The printer 10 detects the color density of the photosensitive area 230 with the detection device 60 and compares the detected density with a reference density. If the difference between the detected density and the reference density is greater than a predetermined threshold, the printer 10 issues a warning. Furthermore, the printer 10 corrects the output of the light irradiation device 50. This adjusts the intensity of the light irradiated by the light irradiation device 50 to within a desired range.

In this embodiment, the photosensitive regions 230 are arranged in a matrix in the main scanning direction Y and the sub-scanning direction X, but the arrangement of the photosensitive regions 230 is not limited. For example, multiple photosensitive regions 230 may be arranged in the sub-scanning direction X. There may be only one photosensitive region 230.

The printer 10 according to the second embodiment can check whether the intensity of the light emitted by the light irradiation device 50 is within a desired range without printing an image. Therefore, the intensity of the light emitted by the light irradiation device 50 can be checked in a shorter time.

A number of suitable embodiments have been described above. However, the inkjet printer of the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, the printer 10 is a flatbed type printer, but the configuration of the printer is not particularly limited. For example, the technology disclosed herein may be applied to a type of printer in which the recording medium is supplied from a roll. The support table that supports the recording medium may be a platen on which the recording medium supplied from the roll is placed.

In the above embodiment, the printer 10 is equipped with one detection device 60, but it may be equipped with multiple detection devices. The multiple detection devices may include multiple types of measuring instruments with different detection targets, such as a densitometer, a gloss meter, a colorimeter, an imaging device, etc. There is no particular limitation on how the multiple types of measuring instruments may be combined.

In the above embodiment, the printer 10 automatically checks whether the intensity of the light irradiated by the light irradiating device 50 is within a desired range. However, the technology disclosed herein can also be implemented in a form that involves the user's work. This method is a method for checking the intensity of light irradiated by the light irradiating device in an inkjet printer that includes a support table that supports a recording medium, an ink head that ejects photocurable ink toward the support table, and a light irradiating device that irradiates light that hardens the ink toward the support table. The above method includes the steps of placing a test piece on the support table, the state of which changes depending on the intensity of the light irradiated by the light irradiating device, irradiating light toward the test piece on the support table with light by the light irradiating device, detecting the state of the test piece after it is placed on the support table and irradiated with light by a detection device that detects the state of the test piece and acquiring detection data, determining the difference between the detection data and reference data previously acquired as data regarding the state of the test piece, and judging whether the difference between the reference data and the detection data exceeds a predetermined threshold. In the above method, the detection device does not need to be provided in the inkjet printer. In addition, in the above method, the process of determining the difference between the reference data and the detection data and the process of determining whether the difference between the reference data and the detection data exceeds a threshold value do not have to be performed by a printer, and may be performed, for example, by a device other than a printer.

Unless otherwise specified, the above embodiments do not limit the present invention.

5 Recording medium 10 Printer (inkjet printer)
20 Flat bed (support stand)
25 Bed moving device (moving device)
35 Carriage moving device (moving device)
40 Recording head 41 First ink head 42 Second ink head 43 Third ink head 50 Light irradiation device 60 Detection device 60A Densitometer 60B Gloss meter 60C Colorimeter 60D Camera (imaging device)
100 Control device 101 Discharge control unit 102 Irradiation control unit 103 Detection control unit 104 Movement control unit 105 Data acquisition unit 106 Reference data storage unit 107 Threshold storage unit 108 Comparison unit 109 Determination unit 110 Warning unit 111 Correction unit 200 Test piece 210 Test pattern (image)
211 to 220 1st region to 10th region D1 Detected concentration (detected data)
Dr Reference concentration (reference data)
ΔD: Difference between reference concentration and detected concentration ΔDr: Threshold

Claims (11)

A support base for supporting the test piece;
an ink head that ejects a photocurable ink toward the support table;
a light irradiation device that irradiates light to cure the ink toward the support table;
A detection device that detects a state of the test piece placed on the support table;
A control device;
Equipped with
the test piece is configured such that, when placed on the support table and irradiated with the light by the light irradiation device, a state of the test piece changes according to an intensity of the irradiated light;
The control device includes:
a reference data storage unit in which reference data relating to the state of the test piece is stored;
an irradiation control unit that controls the light irradiation device to irradiate the light toward the support table;
a detection control unit that controls the detection device to detect the state of the test piece after it is placed on the support base and irradiated with the light at a plurality of detection points on the support base ;
a data acquisition unit that acquires detection data relating to the state of the test piece detected by the detection device;
a comparison unit configured to determine a difference between the reference data and the detection data for each of the plurality of detection points ;
a threshold value storage unit in which a threshold value relating to a difference between the reference data and the detection data is stored;
a determination unit that determines whether a difference between the reference data and the detection data obtained by the comparison unit for each of the plurality of detection points exceeds the threshold value , and detects an abnormality in partial light intensity on the support base ;
An inkjet printer comprising: the test pieces include a first test piece on which an image is formed by ejecting the ink onto a recording medium,
the control device includes an ejection control unit that controls the ink head to eject the ink onto the recording medium to form the first test piece;
the detection device includes a gloss meter capable of measuring a light reflectance of the image of the first test piece,
The reference data storage unit stores reference data regarding a light reflectance of the image of the first test piece.
2. The inkjet printer according to claim 1. the test pieces include a second test piece on which an image is formed by ejecting the ink onto a recording medium,
the control device includes an ejection control unit that controls the ink head to eject the ink onto the recording medium to form the second test piece,
the detection device includes a densitometer capable of measuring the density of the image on the second test piece,
the reference data storage unit stores reference data relating to the density of the image of the second test piece;
3. The inkjet printer according to claim 1 or 2. the image of the second test piece has a plurality of regions each having a different ink ejection density;
4. The inkjet printer according to claim 3. the test pieces include a third test piece on which an image is formed by ejecting the ink onto a recording medium,
the control device includes an ejection control unit that controls the ink head to eject the ink onto the recording medium to form the third test piece;
the detection device includes a colorimeter capable of measuring a color value of the image of the third test piece,
The reference data storage unit stores reference data regarding color values of the image of the third test piece.
5. The inkjet printer according to claim 1. the test pieces include a fourth test piece on which an image is formed by ejecting the ink onto a recording medium,
the control device includes an ejection control unit that controls the ink head to eject the ink onto the recording medium to form the fourth test piece,
the detection device includes an imaging device that captures the image of the fourth test piece to identify a shape of the image,
The reference data storage unit stores reference data regarding a shape of the image of the fourth test piece.
6. The inkjet printer according to claim 1. The control device includes a warning unit that issues a warning when the determination unit determines that the difference between the reference data and the detection data exceeds the threshold value.
The inkjet printer according to any one of claims 1 to 6 . The control device includes a correction unit that corrects an output of the light irradiation device based on a difference between the reference data and the detection data obtained by the comparison unit.
The inkjet printer according to any one of claims 1 to 7 . A support base for supporting the test piece;
an ink head that ejects a photocurable ink toward the support table;
a light irradiation device that irradiates light to cure the ink toward the support table;
A detection device that detects a state of the test piece placed on the support table;
A control device;
Equipped with
the test piece includes a photoreceptor that, when placed on the support table and irradiated with the light by the light irradiation device, changes in color density according to the intensity of the irradiated light,
the detection device includes a densitometer capable of measuring the color density of the photoconductor ;
The control device includes:
a reference data storage unit in which reference data relating to the color density of the photoconductor is stored;
an irradiation control unit that controls the light irradiation device to irradiate the light toward the support table;
a detection control unit that controls the detection device to detect the color density of the photoconductor after the photoconductor is placed on the support table and irradiated with the light;
a data acquisition unit that acquires detection data related to the color density of the photoconductor detected by the detection device;
a comparison unit configured to determine a difference between the reference data and the detection data;
a threshold value storage unit in which a threshold value relating to a difference between the reference data and the detection data is stored;
a determination unit that determines whether a difference between the reference data and the detection data obtained by the comparison unit exceeds a threshold value;
An inkjet printer comprising : A support base for supporting the test piece;
an ink head that ejects a photocurable ink toward the support table;
a light irradiation device that irradiates light to cure the ink toward the support table;
A detection device that detects a state of the test piece placed on the support table;
a moving device that changes a positional relationship between the support table and the detection device by moving at least one of the support table and the detection device ;
A control device;
Equipped with
the test piece is configured such that, when placed on the support table and irradiated with the light by the light irradiation device, a state of the test piece changes according to an intensity of the irradiated light;
The control device includes:
a reference data storage unit in which reference data relating to the state of the test piece is stored;
an irradiation control unit that controls the light irradiation device to irradiate the light toward the support table;
a detection control unit that controls the detection device to detect a state of the test piece after it is placed on the support base and irradiated with the light;
a data acquisition unit that acquires detection data relating to the state of the test piece detected by the detection device;
a comparison unit configured to determine a difference between the reference data and the detection data;
a threshold value storage unit in which a threshold value relating to a difference between the reference data and the detection data is stored;
a determination unit that determines whether a difference between the reference data and the detection data obtained by the comparison unit exceeds a threshold value;
a movement control unit that controls the moving device to move the detection point of the detection device on the support base ;
An inkjet printer comprising : A method for confirming the intensity of light irradiated by a light irradiation device in an inkjet printer including a support table, an ink head that ejects light-curable ink toward the support table, and a light irradiation device that irradiates light to cure the ink toward the support table, comprising the steps of:
A step of placing a test piece on the support base, the test piece being configured to change in state depending on the intensity of the light irradiated by the light irradiation device;
irradiating the light toward the test piece on the support table with the light irradiation device;
a step of detecting a state of the test piece after it is placed on the support table and irradiated with the light by a detection device that detects the state of the test piece at a plurality of detection points on the support table , and acquiring detection data;
determining a difference between the detection data and previously obtained reference data, the reference data being data relating to the state of the test piece , for each of the plurality of detection points ;
determining whether a difference between the reference data and the detection data for each of the plurality of detection points exceeds a predetermined threshold value , and detecting an abnormality in partial light intensity on the support base ;
A method for checking light intensity, including:

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