Inkjet printer

Abstract

To reduce a possibility of damage of an inkjet head by received light.SOLUTION: An inkjet printer 10 includes inkjet heads 41 to 43 provided on a carriage 30, a light irradiation device 50, and a photosensor 60 provided on the carriage 30. The inkjet printer 10 receives a print start command, then controls the light irradiation device 50 and emits light, and acquires intensity of the light measured by the photosensor 60 when the light is emitted. The inkjet printer 10 compares the acquired intensity of the light with a first threshold, and issues a print cancel command when the acquired intensity of the light exceeds the first threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to inkjet printers. [Background technology]

[0002] Inkjet printers have been known that include an inkjet head that ejects photocurable ink that hardens when exposed to light in a specific wavelength range onto a recording medium, and a light irradiation device that irradiates light to harden the photocurable ink. In such inkjet printers, it has been pointed out that the light irradiated by the light irradiation device is reflected by the recording medium and irradiated onto the inkjet head, causing the photocurable ink attached to the surface of the inkjet head and the photocurable ink in the nozzles to thicken or harden. For this reason, many inkjet printers that use photocurable ink are provided with a structure (e.g., a light shielding plate) that prevents the reflected light from being irradiated onto the inkjet head.

[0003] However, since it is difficult to completely eliminate the reflected light irradiated to the inkjet head, in many of such inkjet printers, cleaning of the inkjet head is performed periodically or at appropriate times. For example, Patent Document 1 discloses an inkjet printer that measures the accumulated amount of light irradiated to an optical sensor provided near the inkjet head (ejection head), and issues a warning or cleans the inkjet head when the measured accumulated amount of light exceeds a predetermined threshold. According to Patent Document 1, since the amount of light irradiated to the optical sensor and the amount of light irradiated to the inkjet head are almost equal, it is said that the amount of light measured by the optical sensor can replace the amount of light received by the inkjet head. Since the amount of reflected light varies greatly depending on, for example, the type of recording medium, it has been difficult to set an appropriate timing for cleaning, but in the inkjet printer disclosed in Patent Document 1, the amount of light received by the inkjet head is measured almost accurately, so it is said that it is possible to know the appropriate timing for cleaning the inkjet head. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-97130 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the inkjet printer disclosed in Patent Document 1, it is intended to clean the inkjet head before the ink thickens or hardens by measuring the cumulative amount of light received by the optical sensor. This reduces the risk of the inkjet head being damaged by the ink thickening or hardening. However, the inkjet printer disclosed in Patent Document 1 does not assume that the inkjet head will be irradiated with strong reflected light that will harden the ink in a short time. The inventor of the present application realized that if the intensity (instantaneous amount of light) of the light irradiated to the inkjet head is excessively high, the ink may thicken or harden even with a short irradiation, causing damage to the inkjet head.

[0006] The present invention has been made in consideration of the above-mentioned points, and its object is to provide an inkjet printer that uses photocurable ink and that can further reduce the risk of damage to the inkjet head due to the light it receives. [Means for solving the problem]

[0007] The inkjet printer disclosed herein includes a support table for supporting a recording medium, a carriage provided to face the support table, an inkjet head provided on the carriage, a light irradiation device, an optical sensor for measuring the intensity of received light, and a control device. The inkjet head has a nozzle surface in which a plurality of nozzles for ejecting ink are formed, and the inkjet head is provided on the carriage so that the nozzle surface faces the support table. The light irradiation device includes a light source for irradiating light for curing the ink, and is provided to face the support table. The optical sensor is provided on the carriage so as to face the support table. The control device includes a receiving unit, an irradiation command unit, an acquisition unit, a first threshold registration unit, a first comparison unit, and a first command unit. The receiving unit receives a print start command. The irradiation command unit controls the light irradiation device to irradiate light after the receiving unit receives the print start command. The acquisition unit acquires the intensity of light measured by the optical sensor when the irradiation command unit causes the light irradiation device to irradiate light. The first threshold registration unit registers a first threshold related to the intensity of light acquired by the acquisition unit. The first comparison unit compares the intensity of light acquired by the acquisition unit with the first threshold. The first command unit issues a print stop command when the intensity of light acquired by the acquisition unit exceeds the first threshold.

[0008] When the inkjet printer receives a print start command, it irradiates light from a light irradiation device and measures the intensity of the light received by an optical sensor provided on the carriage. Because the optical sensor is provided on the carriage on which the inkjet head is provided, it is considered that the intensity of light received by the optical sensor is close to the intensity of light received by the inkjet head. In the inkjet printer, if the intensity of light measured by the optical sensor exceeds a first threshold, a print stop command is issued and printing is not performed. This reduces the risk of the inkjet head being damaged due to excessive light intensity received by the inkjet head. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a front view illustrating a printer according to an embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a plan view showing the configuration of the lower surface of the carriage. [Figure 4] FIG. 2 is a block diagram of a printer. [Diagram 5] 10 is a flowchart relating to a determination as to whether printing can be executed. [Figure 6] FIG. 11 is a perspective view showing a printer according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described here is not intended to limit the present invention in any particular way. In addition, the same reference numerals are used for members and parts that perform the same function, and duplicated descriptions are omitted or simplified as appropriate.

[0011] FIG. 1 is a front view of an inkjet printer (hereinafter, referred to as printer) 10 according to an embodiment. FIG. 2 is a right side view of the main part of the printer 10. FIG. 1 shows the printer 10 with the front cover 12 open. In the following description, unless otherwise specified, the side away from the printer 10 is the front, and the side approaching the printer 10 is the rear, when the printer 10 is viewed from the front. The terms left, right, top, and bottom refer to the left, right, top, and bottom of the printer 10 when viewed from the front. 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 here. The symbol X indicates the sub-scanning direction. The sub-scanning direction X is the front-rear direction here. 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 explanation, and do not limit the installation mode of the printer 10 or the present invention in any way.

[0012] In this embodiment, the printer 10 is an inkjet printer. In this embodiment, the term "inkjet printer" refers to inkjet printers using various conventionally known 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.

[0013] As shown in Fig. 1, a printer 10 according to this embodiment is formed in a box shape. The printer 10 here includes a case 11 and a front cover 12. As shown in Fig. 1, an opening is formed in the front of the case 11. The front cover 12 is provided so as to be able to freely open and close the opening of the case 11. Here, the front cover 12 is supported by the case 11 so as to be rotatable about its rear end as an axis.

[0014] 1 and 2, the printer 10 has an internal space provided with a flatbed 20, a carriage 30, a recording head 40, a light irradiation device 50, an optical sensor 60, a moving device 70, a height detection device 80, a capping device 90, a wiping device 95, and a control device 100 (see FIG. 4). The capping device 90 and the wiping device 95 are an example of a cleaning mechanism that removes ink from within the nozzles of the recording head 40 to clean the recording head 40.

[0015] The flatbed 20 is a support platform that supports the recording medium 5. The printer 10 according to this embodiment is a so-called flatbed type printer. The flatbed 20 is a flat-plate member. The recording medium 5 is placed on the upper surface of the flatbed 20. The flatbed 20 extends in the main scanning direction Y and the sub-scanning direction X. The flatbed 20 is provided substantially horizontally. 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.

[0016] The carriage 30 is mounted with a recording head 40, a light irradiation device 50, and an optical sensor 60. The carriage 30 is provided so as to face the flat bed 20. The carriage 30 is disposed above the flat bed 20.

[0017] Fig. 3 is a plan view showing the configuration of the underside of the carriage 30. As shown in Fig. 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 inkjet head 41, a second inkjet head 42, and a third inkjet head 43.

[0018] As shown in FIG. 3, the first inkjet head 41 has a nozzle surface 41b in which a plurality of nozzles 41a for ejecting ink are formed. The first inkjet head 41 is provided on the carriage 30 such that the nozzle surface 41b faces the flatbed 20. The second inkjet head 42 and the third inkjet head 43 are configured similarly to the first inkjet head 41. Note that although the first inkjet head 41 to the third inkjet head 43 shown in FIG. 3 each have a small number of nozzles, in reality, a larger number of nozzles (for example, 300 nozzles) are formed. The number of nozzles provided in the first inkjet head 41 to the third inkjet head 43 is not particularly limited.

[0019] 3, the first inkjet head 41 to the third inkjet head 43 all extend in the sub-scanning direction X. The first inkjet head 41 to the third inkjet head 43 are arranged side by side in the main scanning direction Y. Note that the number of inkjet heads included in the recording head 40 is three here, but is not particularly limited. The arrangement of the multiple ink heads is also not limited, and for example, some or all of the multiple ink heads may be arranged in a staggered manner.

[0020] In this embodiment, all of the inks ejected from the first inkjet head 41 to the third inkjet head 43 are photocurable inks. The photocurable inks are ultraviolet-curable inks that are cured when irradiated with ultraviolet rays. The components, characteristics, etc. of the photocurable inks are not particularly limited.

[0021] 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 is provided so as to face the flatbed 20. As shown in FIG. 3, the light irradiation device 50 includes a light source 51 and an irradiation port 52. The light source 51 irradiates light to harden the ink. The light source 51 is composed of, for example, a plurality of ultraviolet irradiation LEDs. The irradiation port 52 is provided so as to face the flatbed 20. 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 irradiation port 52 is aligned with the recording head 40 in the main scanning direction Y. The light generated by the light source 51 passes through the irradiation port 52 and is irradiated onto the recording medium 5 on the flatbed 20.

[0022] The optical sensor 60 is provided on the carriage 30 so as to face the flatbed 20. The optical sensor 60 is disposed on the lower surface of the carriage 30. The optical sensor 60 is a sensor that measures the intensity of received light. As shown in FIG. 3, the optical sensor 60 is provided between the recording head 40 and the light irradiation device 50. The optical sensor 60 is disposed to the left of the recording head 40 and to the right of the light irradiation device 50. The optical sensor 60 mainly measures the intensity of light that is irradiated from the light irradiation device 50, reflected by the recording medium 5 on the flatbed 20, and reaches the optical sensor 60. For example, when there is light that is irradiated from the light irradiation device 50 and reaches the optical sensor 60 directly, the optical sensor 60 measures the intensity of light including such light.

[0023] Here, the light intensity means the amount of light irradiated per predetermined time (instantaneous light amount). The light intensity may be defined, for example, by the irradiance of light (the energy of light irradiated per unit time to a unit area). Alternatively, the light intensity may be defined by the radiance or radiant intensity of light. The definition of the light intensity is not particularly limited as long as the same measurement method is used each time the light intensity is measured. The integrated light amount is obtained by integrating the light intensity along the time axis.

[0024] The moving device 70 is configured to move the flatbed 20 relative to the carriage 30 by moving the flatbed 20 and the carriage 30. Here, the moving device 70 includes a main scanning direction moving device 70Y that moves the carriage 30 in the main scanning direction Y, a sub-scanning direction moving device 70X that moves the flatbed 20 in the sub-scanning direction X, and a vertical direction moving device 70Z that moves the flatbed 20 in the vertical direction Z. However, it is sufficient that the moving device 70 is configured to move the flatbed 20 relative to the carriage 30 by moving at least one of the flatbed 20 and the carriage 30, and there is no limitation as to in which direction the flatbed 20 and the carriage 30 move or do not move.

[0025] The main scanning direction moving device 70Y includes a guide rail 71, a belt 72, left and right pulleys (not shown), and a carriage motor 73 (see FIG. 4). As shown in FIG. 1, the guide rail 71 extends in the main scanning direction Y. The carriage 30 is slidably engaged with the guide rail 71. An endless belt 72 is fixed to the carriage 30. The belt 72 is wound around pulleys (not shown) provided on the right and left sides of the guide rail 71. A carriage motor 73 is attached to one of the pulleys. When the carriage motor 73 is driven, the pulley rotates and the belt 72 runs. As a result, the carriage 30 moves in the main scanning direction Y along the guide rail 71.

[0026] The sub-scanning direction moving device 70X and the vertical direction moving device 70Z are provided below the flatbed 20. The vertical direction moving device 70Z supports the flatbed 20 and moves it in the vertical direction Z. The vertical direction moving device 70Z is supported from below by the sub-scanning direction moving device 70X. The sub-scanning direction moving device 70X supports the vertical direction moving device 70Z and moves it in the sub-scanning direction X.

[0027] The height detection device 80 measures the height of the recording medium 5 supported by the flatbed 20 from the flatbed 20. Here, the height detection device 80 measures the height of the recording medium 5 from the flatbed 20 by measuring the position in the vertical direction Z of the flatbed 20 at the boundary between contact and non-contact of the recording medium 5 with the height detection device 80. As shown in FIG. 2, the height detection device 80 includes a detection plate 81, a swing shaft 82, and a sensor 83 (see FIG. 4). As shown in FIG. 1, the detection plate 81 is configured in a flat plate shape extending in the main scanning direction Y and the vertical direction Z. The swing shaft 82 is disposed above the detection plate 81 and extends in the main scanning direction Y. The swing shaft 82 supports the detection plate 81 so that it can swing in the sub-scanning direction X. The sensor 83 detects that the detection plate 81 is tilted from the vertical. The sensor 83 is, for example, an optical sensor.

[0028] When the flatbed 20 is moved in the sub-scanning direction X while the flatbed 20 is positioned at a height where the recording medium 5 can contact the detection plate 81, the recording medium 5 comes into contact with the detection plate 81. This contact causes the detection plate 81 to tilt from the vertical. The sensor 83 detects the tilt of the detection plate 81. The printer 10 measures the height of the recording medium 5 from the flatbed 20 by performing the above detection while raising or lowering the height of the flatbed 20 in stages. However, the configuration of the height detection device 80 is not particularly limited. The height detection device 80 may measure the height of the recording medium 5 by irradiating the recording medium 5 with ultrasonic waves or a laser, for example.

[0029] The capping device 90 protects the inkjet heads 41 to 43 and sucks ink from the nozzles of the inkjet heads 41 to 43. The ink sucking is one of the cleaning operations of the inkjet heads 41 to 43. The cleaning of the inkjet heads 41 to 43 refers to the operation of removing at least a part of the ink in the nozzles. As shown in FIG. 1, the capping device 90 includes a plurality of caps 91, a cap moving unit 92, and a suction pump 93. The plurality of caps 91 are configured so as to be attachable to the inkjet heads 41 to 43, respectively. The cap moving unit 92 moves the plurality of caps 91 in the up-down direction Z to attach or detach the caps 91 from the inkjet heads 41 to 43. The suction pump 93 reduces the pressure in the caps 91 while the caps 91 are attached to the inkjet heads 41 to 43, thereby sucking ink from the nozzles.

[0030] As shown in FIG. 2, the wiping device 95 includes a wiper 96 and a wiper moving section 97. The wiper 91 is disposed behind the carriage 30 when not wiping. The wiper 96 is configured in a flat plate shape extending in the main scanning direction Y and the up-down direction Z. The wiper 96 is formed of, for example, rubber. The wiper moving section 97 moves the wiper 96 in the sub-scanning direction X to bring it into contact with the nozzle faces of the inkjet heads 41 to 43. The nozzle faces of the inkjet heads 41 to 43 are wiped by the wiper 96 moving in the sub-scanning direction X. Wiping is one of the cleaning methods for the inkjet heads 41 to 43. The configuration of the wiping device 95 is not limited to the above. Wiping may be performed, for example, by moving the carriage 30, or may be performed so as to proceed in the main scanning direction Y.

[0031] FIG. 4 is a block diagram of the printer 10. As shown in FIG. 4, the control device 100 is connected to the first inkjet head 41 to the third inkjet head 43, the light source 51 of the light irradiation device 50, the carriage motor 73, the sub-scanning direction moving device 70X, the vertical direction moving device 70Z, the cap moving unit 92, the suction pump 93, and the wiper moving unit 97, and controls their operations. The control device 100 is also connected to the optical sensor 60 and the sensor 83 of the height detection device 80, and receives signals therefrom. The control device 100 is, for example, a computer, and may include a central processing unit (hereinafter referred to as CPU), a ROM in which a program executed by the CPU is stored, a RAM, and the like. Each unit of the control device 100 may be configured by software or hardware. The configuration of the control device 100 is not particularly limited.

[0032] The printer 10 according to this embodiment is configured to determine before printing whether the inkjet heads 41-43 may be damaged during printing due to light irradiated by the light irradiation device 50 and reflected by the recording medium 5. The printer 10 determines the above-mentioned risk by actually irradiating the recording medium 5 with light before starting printing. If the printer 10 determines that the inkjet heads 41-43 may be damaged during printing, it does not perform printing. It is assumed that the intensity of light received by the inkjet heads 41-43 is approximately equal to the intensity of light measured by the optical sensor 60.

[0033] 4, the control device 100 includes a data receiving unit 101, a setup control unit 102, a print control unit 103, an irradiation command unit 104, a first intensity registration unit 105, a second intensity registration unit 106, a light amount acquisition unit 107, a first threshold registration unit 108, a first comparison unit 109, a first stop command unit 110, an integrated light amount estimation unit 111, a second threshold registration unit 112, a second comparison unit 113, a second stop command unit 114, a third threshold registration unit 115, a third comparison unit 116, and a cleaning control unit 117. The control device 100 may include other control units, but the description and illustration thereof will be omitted here.

[0034] The data receiving unit 101 is configured to receive print data and a print start command. The print data and the print start command are transmitted, for example, from an external device connected to the printer 10. However, the print start command may be issued by operating an operation panel of the printer 10 or the like. The print data may be stored in the printer 10.

[0035] The setup control unit 102 performs a predetermined setup operation after the data receiving unit 101 receives a print start command and before printing starts. The setup operation includes setting the height of the flatbed 20.

[0036] The print control unit 103 controls the printing operation of the printer 10. Based on the print data, the print control unit 103 controls the inkjet heads 41-43 to eject ink from a plurality of nozzles, thereby causing the ink to land on the recording medium 5 supported by the flatbed 20. The print control unit 103 further controls the light irradiation device 50 to irradiate light, thereby curing the ink that has landed. The first intensity registration unit 105 registers the intensity of light that the print control unit 103 causes the light irradiation device 50 to irradiate (hereinafter also referred to as "printing intensity").

[0037] After the data receiving unit 101 receives a print start command, the irradiation command unit 104 controls the light irradiation device 50 to irradiate light. The irradiation of light by the irradiation command unit 104 before printing is for checking the intensity of reflected light from the recording medium 5 that reaches the recording head 40. Hereinafter, this irradiation of light by the irradiation command unit 104 before printing is also referred to as "test irradiation." The second intensity registration unit 106 registers the intensity of light that the irradiation command unit 104 causes the light irradiation device 50 to irradiate (hereinafter, also referred to as "test intensity"). The test intensity is set to be weaker than the intensity during printing.

[0038] The light amount acquiring unit 107 acquires the light intensity measured by the light sensor 60 when the irradiation command unit 104 causes the light irradiation device 50 to irradiate light. A first threshold V1 (see FIG. 5) related to the light intensity acquired by the light amount acquiring unit 107 is registered in the first threshold registration unit 108. The first comparison unit 109 compares the light intensity acquired by the light amount acquiring unit 107 with the first threshold V1. The first stop command unit 110 issues a print stop command when the light intensity acquired by the light amount acquiring unit 107 exceeds the first threshold V1.

[0039] The integrated light amount estimating unit 111 estimates the integrated amount of light received by the light sensor 60 from the start of printing to the end of printing based on the light intensity acquired by the light amount acquiring unit 107 and the print data. Hereinafter, this estimated integrated light amount is also referred to as the estimated integrated light amount. The second threshold registering unit 112 registers a second threshold V2 (see FIG. 5) related to the estimated integrated light amount. The second comparing unit 113 compares the estimated integrated light amount estimated by the integrated light amount estimating unit 111 with the second threshold V2. The second cancel command unit 114 issues a print cancel command when the estimated integrated light amount estimated by the integrated light amount estimating unit 111 exceeds the second threshold V2.

[0040] A third threshold V3 (see FIG. 5) related to the estimated accumulated light amount is registered in the third threshold registration unit 115. The third threshold V3 is set to be smaller than the second threshold V2. The third comparison unit 116 compares the estimated accumulated light amount estimated by the accumulated light amount estimation unit 111 with the third threshold V3. If the estimated accumulated light amount estimated by the accumulated light amount estimation unit 111 is equal to or smaller than the second threshold V2 and exceeds the third threshold V3, the cleaning control unit 117 causes the capping device 90 and the wiping device 95, which serve as a cleaning mechanism, to clean the inkjet heads 41 to 43 before starting printing.

[0041] The following describes the determination of whether printing can be performed by the printer 10. FIG. 5 is a flowchart related to the determination of whether printing can be performed. However, the flowchart shown in FIG. 5 merely shows a preferred example of the determination of whether printing can be performed, and does not limit the process of the determination of whether printing can be performed. As shown in FIG. 5, in step S01 of the determination of whether printing can be performed, print data and a print start command are received. In step S02, the height of the flatbed 20 is set as one of the setup operations before printing. The height setting of the flatbed 20 is an operation for setting the gap between the recording head 40 and the recording medium 5 to an appropriate distance according to the thickness of the recording medium 5. Note that, in the setup operation, operations other than the height setting of the flatbed 20 may be performed, but illustration and description thereof are omitted.

[0042] When setting the height of the flatbed 20, the height of the recording medium 5 is measured. When measuring the height of the recording medium 5, the flatbed 20 is raised in stages and moved in the sub-scanning direction X each time it is raised. When the recording medium 5 comes into contact with the detection plate 81 and the sensor 83 reacts, the printer 10 moves the flatbed 20 in the sub-scanning direction X while lowering it in small increments or at a low speed. This measures the height of the recording medium 5. The height of the flatbed 20 is set based on the measurement result of the height of the recording medium 5. When printing, the height of the flatbed 20 set in step S02 is maintained.

[0043] In step S03, test irradiation is performed. The test irradiation is performed with the flatbed 20 positioned at the height set in step S02. Since the manner in which light is reflected by the recording medium 5 is thought to change depending on the height of the flatbed 20, this allows test irradiation to be performed under conditions close to those during printing. However, the test intensity, which is the intensity of light irradiated by the light irradiation device 50 during test irradiation, is set to be weaker than the intensity during printing.

[0044] In the test irradiation according to this embodiment, the printer 10 first causes the light irradiation device 50 to irradiate light while moving the carriage 30 in the main scanning direction Y with the flatbed 20 stopped. Next, the flatbed 20 is moved in the sub-scanning direction X to change the position of the flatbed 20 in the sub-scanning direction X relative to the carriage 30. Furthermore, at the changed position in the sub-scanning direction X, the carriage 30 is moved in the main scanning direction Y while the light irradiation device 50 irradiates light. The above is repeated until the carriage 30 passes above the entire printing area on the flatbed 20. During this time, light is continuously irradiated from the light irradiation device 50.

[0045] During the test irradiation, the intensity of light received by the optical sensor 60 is measured at any time. The light received by the optical sensor 60 is mainly light irradiated by the light irradiation device 50 and reflected by the recording medium 5. The printer 10 here acquires the intensity of light measured by the optical sensor 60 at predetermined time intervals. Since the carriage 30 is moving during this time, the printer 10 acquires multiple pieces of data measured at different measurement points on the flatbed 20. In this embodiment, the printer 10 acquires the intensity of reflected light over the entire printing area on the flatbed 20.

[0046] The intensity of the light reflected by the recording medium 5 of the light irradiated by the light irradiation device 50 may vary depending on the type of recording medium 5. Furthermore, if the recording medium 5 has a three-dimensional shape, the intensity of the light reflected by the recording medium 5 may vary depending on the position of the recording medium 5 on the flatbed 20 and may also vary depending on the measurement point. In this embodiment, since the intensity of the light reflected by the recording medium 5 may vary depending on the measurement point, the flatbed 20 supporting the recording medium 5 is moved relative to the carriage 30 equipped with the optical sensor 60, and the intensity of the reflected light is acquired over the entire printing area on the flatbed 20.

[0047] In the next step S04, the data with the highest intensity is selected from among the multiple light intensities measured by the optical sensor 60 at multiple points on the flatbed 20. Hereinafter, this highest light intensity is also referred to as the peak intensity P1. In this embodiment, the printer 10 selects the peak intensity P1 as a representative value of the multiple light intensities measured by the optical sensor 60. The "light intensity acquired by the light amount acquisition unit 107" compared with the first threshold value V1, the second threshold value V2, and the third threshold value V3 in the subsequent steps may be the representative value of the multiple intensities, as described above. In this embodiment, the peak intensity P1 is selected as the representative value of the multiple light intensities from the viewpoint of preventing as reliably as possible the defects that may occur in the recording head 40 due to the ink thickening or hardening caused by the reflected light. However, the printer 10 may be configured to use the average value or the median value as the representative value of the multiple light intensities.

[0048] In step S05, it is determined whether the peak intensity P1 obtained in step S04 exceeds the first threshold value V1. If the peak intensity P1 exceeds the first threshold value V1 (if the result of step S05 is YES), the printer 10 issues a print stop command and printing is not started (step S11). In such a case, for example, if the mounting state of the recording medium 5 (e.g., the mounting angle) is changed, the peak intensity P1 may become equal to or smaller than the first threshold value V1. Therefore, the user may change the mounting state of the recording medium 5 and then try to start printing again.

[0049] The first threshold V1 is set based on whether or not there is a risk of the inkjet heads 41-43 being damaged by reflected light during printing. If the peak intensity P1 exceeds the first threshold V1, printing is not started because there is a risk of the inkjet heads 41-43 being damaged by reflected light during printing. When the test intensity is A% of the printing intensity, the first threshold V1 is preferably set to A% of the light intensity that may damage the inkjet heads 41-43 during printing, or in the vicinity thereof. The intensity of the reflected light is roughly proportional to the intensity of the light irradiated by the light irradiation device 50. Therefore, the above conversion is possible.

[0050] If the peak intensity P1 is equal to or less than the first threshold V1 (if the result of step S05 is NO), the estimated integrated light amount Q1 is calculated in step S06. The estimated integrated light amount Q1 may be calculated, for example, by estimating the time required for printing from the amount of print data and integrating it with the peak intensity P1. However, the estimated integrated light amount Q1 may also be calculated, for example, by integrating the average or median value of multiple light intensity data with the estimated printing time. The method of calculating the estimated integrated light amount Q1 is not particularly limited.

[0051] In the next step S07, it is determined whether the estimated integrated light amount Q1 obtained in step S06 exceeds the second threshold V2. If the estimated integrated light amount Q1 exceeds the second threshold V2 (if the result of step S07 is YES), the printer 10 issues a print stop command and printing does not start (step S11).

[0052] The second threshold V2 is set based on whether or not there is a risk of the inkjet heads 41-43 being damaged by reflected light during printing. If the estimated integrated light amount Q1 exceeds the second threshold V2, printing does not start because there is a risk of the inkjet heads 41-43 being damaged by reflected light during printing. When the test intensity is A% of the printing intensity, the second threshold V2 is preferably set to A% of the integrated light amount that may damage the recording head 40 during printing, or in the vicinity thereof.

[0053] If the estimated integrated light amount Q1 is equal to or less than the second threshold V2 (if the result of step S07 is NO), in step S08, it is determined whether the estimated integrated light amount Q1 exceeds a third threshold V3. The third threshold V3 is a threshold for the integrated light amount from the start to the end of printing, and is a threshold for determining whether or not cleaning of the inkjet heads 41 to 43 should be performed before printing. If the estimated integrated light amount Q1 exceeds the third threshold V3 (if the result of step S08 is YES), cleaning of the inkjet heads 41 to 43 is performed in step S09. The cleaning includes, for example, suction of ink by the capping device 90 and wiping by the wiping device 95. However, the content of the cleaning is not particularly limited as long as at least a part of the ink in the nozzles is removed. After that, printing is started in step S10. If the estimated integrated light amount Q1 is equal to or less than the third threshold V3 (if the result of step S08 is NO), printing is started in step S10.

[0054] Although not shown, in this embodiment, the printer 10 acquires the intensity of light received by the optical sensor 60 at a predetermined time interval even after printing has started. The printer 10 stops printing when the intensity of light acquired during printing exceeds a fourth threshold. Here, the fourth threshold is an intensity obtained by converting the first threshold V1 based on the ratio of the intensity during printing to the test intensity. When the intensity of the acquired light exceeds the fourth threshold, there is a risk of damage to the inkjet heads 41 to 43, so printing is interrupted and resumed after a cleaning operation is performed. However, when the intensity of the acquired light exceeds the fourth threshold, printing may be stopped. Although the intensity of the acquired light does not basically exceed the fourth threshold, the printer 10 may be configured in this way in preparation for an unforeseen event.

[0055] In this embodiment, the printer 10 calculates the integrated amount of light received by the optical sensor 60 even after printing has started. This integrated amount of light may be the integrated amount of light starting from the previous cleaning of the inkjet heads 41 to 43. When the integrated amount of light exceeds a fifth threshold, the printer 10 interrupts printing, executes a cleaning operation, and then resumes printing. However, when the integrated amount of light exceeds the fifth threshold, printing may be stopped. Here, the fifth threshold is the intensity obtained by converting the second threshold V2 based on the ratio between the printing intensity and the test intensity.

[0056] Furthermore, in this embodiment, if the maximum value of the intensity of light received by the optical sensor 60 by the end of printing exceeds a sixth threshold, the printer 10 executes cleaning of the inkjet heads 41-43 after printing. The sixth threshold is set to be smaller than the fourth threshold. The sixth threshold is a threshold for determining whether cleaning after printing is necessary when there is no need to stop printing.

[0057] Furthermore, in this embodiment, if the accumulated amount of light received by the optical sensor 60 at the end of printing exceeds a seventh threshold, the printer 10 performs cleaning of the inkjet heads 41-43 after printing. The seventh threshold is set to be smaller than the fifth threshold. The seventh threshold is a threshold for determining whether or not there is a high possibility that the accumulated amount of light will exceed the fifth threshold in the next printing.

[0058] [Effects of the embodiment] As shown in Patent Document 1, in the conventional technology, the risk of damaging the inkjet head is reduced by cleaning the inkjet head based on the integrated light amount measured by an optical sensor. However, the inkjet printer disclosed in Patent Document 1 does not assume that the inkjet head will be irradiated with strong reflected light that will harden the ink in a short time. If the intensity of the light irradiated to the inkjet head is excessively high, the ink may thicken or harden even with a short irradiation, damaging the inkjet head.

[0059] Therefore, the printer 10 according to this embodiment is configured to cause the light irradiation device 50 to irradiate light after receiving a print start command, and to acquire the intensity of the light received by the optical sensor 60 provided on the carriage 30. The printer 10 is further configured to issue a print stop command and not perform printing if the acquired light intensity exceeds a first threshold value V1. This reduces the risk of the inkjet heads 41-43 being damaged by receiving light of excessive intensity.

[0060] In addition, in the conventional inkjet printer shown in Patent Document 1, the integrated light amount of the light received by the optical sensor is acquired during printing. Therefore, there may be cases where the integrated light amount reaches a threshold during printing and printing must be stopped. If printing is stopped midway, ink and recording medium are wasted, and the printing time up to that point is also wasted. It is possible to continue printing even if the integrated light amount reaches a threshold during printing, but in that case, the risk of damaging the inkjet head increases. In contrast, in the printer 10 according to this embodiment, a determination is made as to whether or not to start printing before starting printing. Therefore, it is possible to reduce cases where printing must be stopped midway.

[0061] In this embodiment, the test intensity, which is the intensity of light in the test irradiation, is set to be weaker than the printing intensity, which is the intensity of light in printing, thereby reducing the risk that the ink in the inkjet heads 41 to 43 will thicken or harden due to the reflected light during the test irradiation.

[0062] In this embodiment, the light intensity is acquired at a plurality of points. The intensity of the reflected light of the light irradiated by the light irradiation device 50 may differ depending on the measurement point on the recording medium 5, but with this configuration, the light intensity is acquired at a plurality of points, so that it is possible to reduce the risk of inappropriate determination of whether or not to start printing due to variations in light intensity depending on the measurement point.

[0063] The irradiation command unit 104 only needs to control the moving device 70 to position the flatbed 20 at a plurality of points relative to the carriage 30, and the procedure of the relative movement between the flatbed 20 and the carriage 30 is not limited. The irradiation command unit 104 only needs to cause the light irradiation device 50 to irradiate light at least when the flatbed 20 is positioned at the above-mentioned plurality of points relative to the carriage 30, and does not need to cause the light irradiation to be continuous. The irradiation of light in the test irradiation is not limited to continuous. The light amount acquisition unit 107 only needs to acquire a plurality of light intensities measured by the light sensor 60 when the flatbed 20 is positioned at the above-mentioned plurality of points relative to the carriage 30. The "plurality of points" may be points whose coordinates in the main scanning direction Y and the sub-scanning direction X are predetermined, or may be determined as a result of the relative movement between the flatbed 20 and the carriage 30 and the intermittent acquisition of the light intensity, as in this embodiment. The number and locations of the plurality of points are not particularly limited.

[0064] The printer 10 according to this embodiment is configured to issue a print stop command when the estimated accumulated light amount Q1 exceeds the second threshold value V2. With this configuration, not only is the determination of whether or not to start printing based on the light intensity, but also the determination of whether or not to start printing based on the estimated accumulated light amount. This further reduces the risk of the inkjet heads 41-43 being damaged by receiving reflected light.

[0065] The printer 10 according to this embodiment is configured to have the capping device 90 and wiping device 95, which serve as a cleaning mechanism, clean the inkjet heads 41-43 before printing if the estimated integrated light amount Q1 is equal to or less than the second threshold V2 and exceeds the third threshold V3. With this configuration, when the estimated integrated light amount Q1 does not exceed the second threshold V2 and is not enough to stop printing but is relatively large (exceeds the third threshold V3), cleaning of the inkjet heads 41-43 is performed before printing. This reduces the risk of damage to the inkjet heads 41-43 during printing.

[0066] Furthermore, in this embodiment, the light intensity received by the optical sensor 60 is acquired and the integrated light amount is calculated even during printing, and if each exceeds a predetermined threshold, printing is interrupted or stopped. Therefore, it is possible to reduce the risk of the inkjet heads 41 to 43 being damaged during printing due to an unexpected increase in light intensity or integrated light amount. Furthermore, in this embodiment, the maximum value of the light intensity received by the optical sensor 60 during printing and the integrated light amount are calculated after printing is completed, and if each exceeds a predetermined threshold, cleaning of the inkjet heads 41 to 43 is performed. Therefore, it is possible to reduce the risk of the inkjet heads 41 to 43 being damaged in the next printing.

[0067] [Other embodiments] A preferred embodiment has been described above. However, the inkjet printer of the present invention is not limited to the above embodiment. For example, in the above embodiment, the printer 10 is a flatbed type printer, but is not limited to this. FIG. 6 is a perspective view showing a printer 15 according to another embodiment. As shown in FIG. 6, the printer 15 may be a printer including a platen 25 extending in the sub-scanning direction X and the main scanning direction Y, a conveying device 75X that conveys the recording medium 5 supported by the platen 25 in the sub-scanning direction X, a carriage moving device 75Y that moves the carriage 35 in the main scanning direction Y, an inkjet head 45 provided on the carriage 35, a light irradiation device 55 that irradiates light to harden the ink, and an optical sensor 65 that is provided on the carriage 35 so as to face the platen 25 and measures the intensity of the received light. The printer 15 is a so-called roll-to-roll type printer that performs printing on a sheet-like recording medium 5. The printer 15 may further include an edge detection device 85 that can detect the position of an edge of the recording medium 5 supported by the platen 25. The edge detection device 85 may be provided in the carriage 35. The edge detection device 85 includes, for example, a camera that captures an image of the boundary between the recording medium 5 and the platen 25. However, the configuration of the edge detection device 85 is not particularly limited.

[0068] In this printer 15, the setup operation may include an operation of detecting the position of the end of the recording medium 5 in the main scanning direction Y by operating the end detection device 85 while moving the carriage 35 in the main scanning direction Y by the carriage movement device 75Y. The width of the recording medium 5 is recognized by this setup operation.

[0069] In this embodiment, the irradiation command unit 104 (see FIG. 4) is configured to cause the light irradiation device 55 to irradiate light and perform test irradiation while the setup operation is being performed. In detail, the irradiation command unit 104 causes the light irradiation device 55 to irradiate light while the edge detection device 85 is performing an operation to detect the position of the edge of the recording medium 5 in the main scanning direction Y. The light amount acquisition unit 107 (see FIG. 4) acquires a plurality of light intensities measured by the optical sensor 65 when the position of the edge of the recording medium 5 in the main scanning direction Y is being detected and the carriage 35 is located at a plurality of different points in the main scanning direction Y.

[0070] According to this printer 15, test irradiation is performed during the setup operation, so it is possible to reduce the time until printing starts. Also, by performing test irradiation while detecting the width of the recording medium 5 in the main scanning direction Y while moving the carriage 35 in the main scanning direction Y, it is possible to obtain the intensity of reflected light at multiple different points in the main scanning direction Y without making any special movements of the carriage 35.

[0071] Unless otherwise specified, the above-described embodiment does not limit the present invention. For example, in the above-described embodiment, the number of optical sensors 60 or 65 is one, but it may be more than one. The position of the optical sensor is also not limited, except that it is provided on the carriage so as to face the support base of the recording medium. For example, the multiple optical sensors may be arranged alternately with the multiple inkjet heads in the main scanning direction.

[0072] The configuration of the inkjet printer is not particularly limited. For example, the inkjet printer may be a line head type printer in which the carriage does not move. [Explanation of symbols]

[0073] 10. Inkjet Printer 20 Flatbed (support) 30 Carriage 41~43 Inkjet head 50 Light irradiation device 60 Light Sensor 100 Control device

Claims

1. A support base extending in a predetermined first direction and a second direction perpendicular to the first direction and supporting a recording medium; a carriage provided opposite the support base; an inkjet head having a nozzle surface on which a plurality of nozzles each for ejecting ink are formed, the inkjet head being provided on the carriage such that the nozzle surface faces the support base; a light irradiation device provided opposite the support table and including a light source that irradiates light to cure the ink; an optical sensor provided on the carriage so as to face the support base and for measuring an intensity of received light; a conveying device that conveys the recording medium supported by the support table in the first direction; a carriage moving device that moves the carriage in the second direction; an edge detection device provided on the carriage and capable of detecting a position of an edge of the recording medium supported by the support table; A control device; Equipped with The control device includes: A receiving unit that receives a print start command; an irradiation command unit that controls the light irradiation device to irradiate light after the receiving unit receives the print start command; an acquisition unit that acquires the intensity of light measured by the optical sensor when the irradiation command unit causes the light irradiation device to irradiate light; a first threshold value registration unit in which a first threshold value related to the intensity of the light acquired by the acquisition unit is registered; a first comparison unit that compares the intensity of the light acquired by the acquisition unit with the first threshold; a first command unit that issues a print stop command when the intensity of the light acquired by the acquisition unit exceeds the first threshold; a setup control unit that performs a predetermined setup operation after the receiving unit receives the print start command and before printing is started; Equipped with the setup operation includes an operation of detecting a position of an edge of the recording medium in the second direction by operating the edge detection device while moving the carriage in the second direction by the carriage movement device, the irradiation command unit is configured to cause the light irradiation device to irradiate light during a time period during which the setup operation is being performed, and causes the light irradiation device to irradiate light while the edge detection device is performing an operation of detecting the position of an edge of the recording medium in the second direction; the acquiring unit is configured to acquire the intensity of light measured by the optical sensor while the edge detecting device is detecting the position of the edge of the recording medium in the second direction. Inkjet printer.

2. The acquisition unit is configured to acquire a plurality of light intensities measured by the optical sensor when the carriage is positioned at a plurality of different points in the second direction while the end detection device is in the process of detecting the position of the end of the recording medium in the second direction.

2. The inkjet printer according to claim 1.

3. A support table for supporting a recording medium; a carriage provided opposite the support base; an inkjet head having a nozzle surface on which a plurality of nozzles each for ejecting ink are formed, the inkjet head being provided on the carriage such that the nozzle surface faces the support base; a light irradiation device provided opposite the support table and including a light source that irradiates light to cure the ink; an optical sensor provided on the carriage so as to face the support base and for measuring an intensity of received light; A control device; Equipped with The control device includes: A receiving unit that receives a print start command; an irradiation command unit that controls the light irradiation device to irradiate light after the receiving unit receives the print start command; an acquisition unit that acquires the intensity of light measured by the optical sensor when the irradiation command unit causes the light irradiation device to irradiate light; a first threshold value registration unit in which a first threshold value related to the intensity of the light acquired by the acquisition unit is registered; a first comparison unit that compares the intensity of the light acquired by the acquisition unit with the first threshold; a first command unit that issues a print stop command when the intensity of the light acquired by the acquisition unit exceeds the first threshold; an integrated light amount estimating unit that estimates an integrated amount of light received by the optical sensor from the start of printing to the end of printing based on the light intensity and print data acquired by the acquiring unit; a second threshold registering unit in which a second threshold relating to an integrated amount of light received by the optical sensor from the start of printing to the end of printing is registered; a second comparison unit that compares the integrated amount estimated by the integrated light amount estimation unit with the second threshold; a second command unit that issues a print stop command when the accumulated light amount estimated by the accumulated light amount estimating unit exceeds the second threshold value; Equipped with Inkjet printer.

4. a cleaning mechanism for cleaning the inkjet head; The control device includes: a third threshold value registration unit in which a third threshold value related to an integrated amount of light received by the optical sensor from the start of printing to the end of printing, the third threshold value being smaller than the second threshold value, is registered; a third comparison unit that compares the integrated amount estimated by the integrated light amount estimation unit with the third threshold; a cleaning control unit that causes the cleaning mechanism to clean the inkjet head before starting printing when the integrated amount of light estimated by the integrated light amount estimating unit is equal to or less than the second threshold and exceeds the third threshold; Equipped with 4. The inkjet printer according to claim 3.

5. The control device includes: a print control unit that controls the inkjet head based on print data to eject ink from the plurality of nozzles to cause the ink to land on the recording medium supported by the support table, and controls the light irradiation device to irradiate the ink to cure the landed ink; a first intensity registration unit in which a first intensity, which is the intensity of light that the print control unit causes the light irradiation device to irradiate, is registered; a second intensity registration unit in which a second intensity, which is the intensity of light that the irradiation command unit causes the light irradiation device to irradiate, is registered; Equipped with The second strength is weaker than the first strength.

5. The inkjet printer according to claim 1.

6. a moving device that moves at least one of the support base and the carriage to move the support base relative to the carriage; the irradiation command unit controls the moving device to position the support table at a plurality of points relative to the carriage, and causes the light irradiation device to irradiate light at least when the support table is positioned at the plurality of points relative to the carriage; the acquisition unit is configured to acquire a plurality of light intensities measured by the optical sensor when the support base is positioned at the plurality of points relative to the carriage.

6. The inkjet printer according to claim 1.

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