Tablet printing device and tablet printing method

Abstract

The invention provides a tablet printing device and a tablet printing method, which can stably print tablets while preventing the productivity from being reduced. A tablet printing device (1) according to an embodiment of the present invention is provided with: a supply device (10) that accommodates a plurality of tablets (T) and sequentially supplies the accommodated tablets (T); a transport device (20) that transports the tablets (T) supplied from the supply device (10); a print head (51) which is of an inkjet type and performs printing by ejecting ink droplets onto the tablet (T) conveyed by the conveyance device (20); a maintenance device (80) for maintaining the print head (51); and a control device (90) that controls the print head (51) and the maintenance device (80), the control device (90) causing the maintenance device (80) to execute maintenance at a timing set on the basis of the type of the tablet (T) supplied from the supply device (10) when the print head (51) and the maintenance device (80) are being printed on the tablet (T).

Description

Technical Field

[0001] Embodiments of the present invention relate to a tablet printing device and a tablet printing method. Background Art

[0002] In order to print identification information such as text or marks on tablets, there is known a technology for printing using an inkjet printing head. A tablet printing device using the technology uses a conveyor to convey a plurality of tablets in a row, and ejects ink (e.g., edible ink) from a nozzle of an inkjet printing head disposed above the conveyor toward tablets passing under the printing head, thereby printing identification information on the tablets on the conveyor.

[0003] In order to maintain the ejection performance of an inkjet print head, the print head is regularly maintained. More specifically, as maintenance, wiping is performed to remove ink or the like attached to the surface of the print head where the nozzles are provided (nozzle surface), and virtual ejection is performed to discharge a certain amount of ink from the nozzles in order to maintain stable ejection from the nozzles.

[0004] [Prior art literature]

[0005] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-58220 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] Among tablets, there are tablets that are not coated on the surface, such as uncoated tablets or orally disintegrating (OD) tablets (orally disintegrating tablets) (hereinafter referred to as uncoated tablets). With regard to such tablets, the fine powder constituting the tablets is easily separated from the tablets. Moreover, if the fine powder separated from the tablets adheres to the nozzle surface of the printing head, it will cause poor ejection. Therefore, when considering printing on uncoated tablets, it is necessary to set the timing of maintenance in accordance with the characteristics of the uncoated tablets. However, the tablets cannot be printed during the maintenance process, so if maintenance is performed frequently, productivity will be reduced.

[0009] An object of the present invention is to provide a tablet printing device and a tablet printing method which can stably print tablets while preventing a decrease in productivity.

[0010] [Technical means to solve the problem]

[0011] The tablet printing device of the embodiment includes: a supply device, which accommodates a plurality of tablets and supplies the accommodated tablets in sequence; a conveying device, which conveys the tablets supplied from the supply device; a printing head, which is an inkjet type, which prints by ejecting ink droplets on the tablets conveyed by the conveying device; a maintenance device, which performs maintenance on the printing head; and a control device, which controls the printing head and the maintenance device, wherein the control device, when executing printing on the tablets, causes the maintenance device to perform maintenance at a timing set based on the type of the tablets supplied from the supply device.

[0012] The tablet printing method of the embodiment includes: a supply process, in which tablets are supplied in sequence; a conveying process, in which the supplied tablets are conveyed in sequence; a printing process, in which ink droplets are ejected from an inkjet printing head to print on the conveyed tablets; and a maintenance process, in which maintenance is performed on the printing head at a specified timing, wherein the maintenance process performed when executing the printing process is performed at a timing set based on the type of the tablets supplied.

[0013] The tablet printing device of the embodiment is characterized in that it includes: a supply device, which accommodates a plurality of tablets and supplies the accommodated tablets in sequence; a conveying device, which conveys the tablets supplied from the supply device; a printing head, which is an inkjet type, which prints by ejecting ink droplets on the tablets conveyed by the conveying device; a maintenance device, which maintains the printing head; and an eraser maintenance device, which maintains an eraser included in the maintenance device, wherein the eraser includes an eraser that wipes the nozzle surface of the printing head to absorb liquid attached to the nozzle surface, and the eraser maintenance device includes a suction nozzle that sucks the liquid held by the eraser.

[0014] The tablet printing method of the embodiment is characterized in that it includes: a supply process, in which tablets are supplied in sequence; a conveying process, in which the supplied tablets are conveyed in sequence; a printing process, in which ink droplets are ejected from an inkjet printing head to print on the conveyed tablets; a printing head maintenance process, in which maintenance is performed using a maintenance device, the maintenance device having a suction portion for sucking the nozzle surface of the printing head, and an eraser for wiping the nozzle surface of the printing head; and an eraser maintenance process, in which liquid retained by the eraser is sucked using a suction nozzle, wherein a suction source that applies suction force to the suction nozzle and a suction source that applies suction force to the suction portion are common.

[0015] [Effects of the Invention]

[0016] According to the embodiment of the present invention, it is possible to stably print on tablets while preventing a decrease in productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a front view showing a schematic structure of the tablet printing device according to the first embodiment.

[0018] Figure 2 It is a plan view showing a schematic structure of the tablet printing device according to the first embodiment.

[0019] Figure 3 This is a diagram showing an example of a schematic configuration of the maintenance device according to the first embodiment.

[0020] Figure 4 This is a diagram showing an example of a schematic configuration of a control device according to the first embodiment.

[0021] Figure 5 This is an operational state diagram of the maintenance device according to the first embodiment.

[0022] Figure 6 It is a diagram showing an example of a schematic configuration of a maintenance device according to a second embodiment.

[0023] Figure 7 It is a flowchart which shows the maintenance process of 2nd Embodiment.

[0024] Figure 8 It is a diagram showing an example of a part of the maintenance device according to the second embodiment.

[0025] [Explanation of Symbols]

[0026] 1: Tablet printing device

[0027] 10: Supply device

[0028] 20: Transport device

[0029] 21: Conveyor belt

[0030] 30: Detection device

[0031] 40: First camera device

[0032] 50: Printing device

[0033] 51: Printing head

[0034] 60: Second camera device

[0035] 70: Recovery device

[0036] 80: Maintenance device

[0037] 81: Liquid receiving part

[0038] 82: Suction unit

[0039] 83: Eraser

[0040] 83a: First Eraser

[0041] 83b: Second eraser

[0042] 84: Mobile mechanism

[0043] 90: Control device

[0044] T: Tablet DETAILED DESCRIPTION

[0045] <First embodiment>

[0046] Reference Figure 1 to Figure 5 A first embodiment will be described.

[0047] (Configuration Example of Tablet Printing Device)

[0048] like Figure 1 and Figure 2 As shown, the tablet printing device 1 of the first embodiment includes: a supply device 10, a conveying device 20, a detection device 30, a first imaging device 40, a printing device 50, a second imaging device 60, a recovery device 70, and a maintenance device 80 (see Figure 2 ) and a control device 90.

[0049] The supply device 10 includes a hopper 11 and a chute 12. The supply device 10 is located at one end of the conveying device 20 and is configured to supply tablets T as printing objects to the conveying device 20. The hopper 11 accommodates a plurality of tablets T and sequentially supplies the accommodated tablets T to the chute 12. The chute 12 arranges the tablets T supplied from the hopper 11 in a row and supplies them to the conveying device 20. The supply device 10 is electrically connected to the control device 90, and its driving is controlled by the control device 90.

[0050] The conveying device 20 includes: a conveying belt 21, a driving pulley 22, a plurality of driven pulleys 23, a motor 24, a position detector 25 and a suction chamber 26. The conveying belt 21 is an endless belt, which is mounted on the driving pulley 22 and each driven pulley 23. The driving pulley 22 and each driven pulley 23 are rotatably arranged on the device body (not shown), and the driving pulley 22 is connected to the motor 24. The motor 24 is electrically connected to the control device 90, and its driving is controlled by the control device 90. The position detector 25 is a device such as an encoder, which is installed on the motor 24. The position detector 25 is electrically connected to the control device 90, and sends a detection signal to the control device 90. In the conveying device 20, the conveying belt 21 and each driven pulley 23 rotate together due to the rotation of the driving pulley 22 caused by the motor 24, so that the tablets T on the conveying belt 21 are moved to the conveying chamber 26. Figure 1 The conveyor is conveyed in the rotation direction of the arrow H1 in FIG.

[0051] The conveyor belt 21 is formed with a plurality of circular suction holes 21a (see Figure 2 ). These suction holes 21a are through holes for adsorbing tablets T, and are arranged in two parallel rows along the conveying direction H1 to form two conveying paths. Each suction hole 21a is formed in the suction chamber 26 (refer to Figure 1 ) is connected to the inside of the suction chamber 26, so that a suction force can be obtained through the suction chamber 26. The suction chamber 26 is connected to a pump (not shown) via a suction pipe, and the suction chamber 26 is depressurized by the operation of the pump. The suction pipe is connected to the approximate center of the side surface (the surface parallel to the conveying direction H1) of the suction chamber 26. In addition, the pump is electrically connected to the control device 90, and its driving is controlled by the control device 90. When the inside of the suction chamber 26 is depressurized, the tablets T placed on the suction holes 21a of the conveyor belt 21 are sucked by the suction holes 21a and held on the conveyor belt 21.

[0052] The detection device 30 includes a plurality of detection units 31 (two in this embodiment). The detection unit 31 is located on the downstream side of the conveying direction H1 relative to the installation position of the supply device 10 and is installed above the conveyor belt 21. The detection unit 31 detects the X direction (refer to Figure 2 ) is detected. As the detection unit 31, for example, a displacement sensor or a proximity sensor is used. In addition, as the displacement sensor, for example, various laser sensors such as a reflective laser sensor are used. The detection device 30 is electrically connected to the control device 90 and sends a detection signal to the control device 90.

[0053] The first camera device 40 includes a plurality of first camera units 41 (two in the present embodiment). The first camera unit 41 is located at the downstream side of the conveying direction H1 more than the setting position of the detection device 30, and is arranged above the conveyor belt 21. The first camera unit 41 takes pictures at the shooting time when the tablet T reaches the shooting position directly below the first camera unit 41 based on the position information of the tablet T in the X direction detected by the detection device 30, obtains a first image (image for tablet position detection) including the upper surface of the tablet T, and sends the obtained first image to the control device 90. The first image is used to detect the position of the tablet T in the X direction, the Y direction and the θ direction. As the first camera unit 41, various cameras having a camera element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) are used. The first camera device 40 is electrically connected to the control device 90, and its drive is controlled by the control device 90. In addition, lighting for shooting is also provided as needed.

[0054] Here, the position of the tablet T in the X direction and the Y direction is, for example, the position in the XY coordinate system relative to the center (reference position) of the imaging area of ​​the first imaging unit 41. In addition, the position in the θ direction is, for example, the position indicating the degree of rotation of the tablet T relative to the center line in the Y direction of the imaging area of ​​the first imaging unit 41. When the tablet T has a directional shape, such as when a dividing line is provided in the tablet T or when the tablet T is formed into an ellipse, an oblong, a quadrilateral, etc., the position in the θ direction is detected.

[0055] The printing device 50 includes a printing head 51 and a lifting mechanism 52. The printing head 51 is located downstream of the first imaging device 40 in the conveying direction H1 and is disposed above the conveyor belt 21. The printing head 51 includes a plurality of (e.g., several hundred to several thousand) nozzles 51a (see Figure 2 ), the direction in which the nozzles 51a are arranged in a row (nozzle row) is arranged in a horizontal plane so as to be orthogonal to (an example of intersecting) the conveying direction H1. Figure 2 In order to simplify the figure, four nozzles 51a are shown. The printing head 51 ejects ink from each nozzle 51a individually by the operation of the driving element of each nozzle 51a. As the printing head 51, various inkjet printing heads having driving elements such as piezoelectric elements, heating elements, or magnetostrictive elements are used. The printing head 51 is driven by a lifting mechanism 52 (see Figure 1 ), and can move up and down in a manner close to or away from the conveyor belt 21. The lifting and lowering movement of the print head 51 is performed when the print head 51 is maintained. The maintenance of the print head 51 will be described later. The printing device 50 is electrically connected to the control device 90, and its driving is controlled by the control device 90.

[0056] The second camera device 60 includes a plurality of second camera units 61 (two in the present embodiment). The second camera unit 61 is located at a position downstream of the conveying direction H1 relative to the setting position of the printing device 50, and is arranged above the conveyor belt 21. The second camera unit 61 takes a picture at a shooting time when the tablet T reaches the shooting position directly below the second camera unit 61 based on the position information of the tablet T in the X direction detected by the first camera unit 41 and the detection unit 31, obtains a second image including the upper surface of the tablet T, and sends the obtained second image to the control device 90. The second image is used to inspect the printed pattern printed on the tablet T. As the second camera unit 61, various cameras having a camera element such as a CCD or CMOS are used, similarly to the first camera unit 41. The second camera device 60 is electrically connected to the control device 90, and its drive is controlled by the control device 90. In addition, lighting for shooting is also provided as needed.

[0057] The recovery device 70 is located at the downstream side of the conveying direction H1 more than the installation position of the second camera device 60, and is installed at the end of the downstream side of the conveying direction H1 in the conveying device 20. The conveying device 20 releases the holding of the tablet T when the tablet T on the conveyor belt 21 reaches a predetermined position, for example, the end of the downstream side of the conveying direction H1 in the conveying device 20. The recovery device 70 is configured to separate the tablets T that fall after the holding by the conveying device 20 is released into defective products and good products for recovery. For example, by blowing gas to the tablets T in the middle of falling, the falling direction of the tablets T is changed according to defective products and good products, or by using components such as plates to change the falling path, the fallen tablets T can be separated into defective products and good products for recovery. For example, defective products are unqualified printing tablets, and good products are qualified printing tablets. The recovery device 70 is electrically connected to the control device 90, and its drive is controlled by the control device 90.

[0058] like Figure 2 and Figure 3 As shown, the maintenance device 80 includes: a liquid receiving portion 81, a suction portion 82, an eraser 83 and a moving mechanism 84. The maintenance device 80 is arranged in the direction in which the nozzles 51a of the print head 51 are arranged when viewed from above ( Figure 2 In addition, Figure 2 In order to simplify the figure, the moving mechanism 84 is omitted. The details of the maintenance device 80 will be described later.

[0059] When performing maintenance on the print head 51, the maintenance device 80 moves between the conveyor belt 21 and the print head 51 to clean the lower surface (nozzle surface) of the print head 51. The maintenance device 80 is electrically connected to the control device 90, and its driving is controlled by the control device 90.

[0060] The control device 90 controls each part of the tablet printing device 1, such as the supply device 10 or the conveying device 20, the detection device 30, the first imaging device 40, the printing device 50, the second imaging device 60, the recovery device 70, the maintenance device 80, etc., based on various information and various programs. In addition, the control device 90 receives detection information (such as a detection signal) and the like sent from the position detector 25 or the detection device 30, and receives image information and the like sent from the first imaging unit 41 or the second imaging unit 61. The control device 90 is implemented, for example, by an electronic circuit such as an integrated circuit or a computer.

[0061] Next, refer to Figure 4 A configuration example of the control device 90 will be described.

[0062] like Figure 4As shown, the control device 90 has an image processing unit 91, a storage unit 92 and a control unit 93. An input device 90a or an output device 90b is connected to the control device 90. The input device 90a is implemented by, for example, a switch or a touch screen, a keyboard, a mouse, etc. In addition, the output device 90b is implemented by, for example, a display, a lamp, a meter, etc.

[0063] The image processing unit 91 imports the first image captured by the first camera device 40 and the second image captured by the second camera device 60, and processes the images using known image processing techniques. For example, the image processing unit 91 processes the first image obtained from the first camera device 40 to obtain whether the tablet T has cracks, notches, or dirt, and further obtains the position of the tablet T in the X direction, Y direction, and θ direction. In addition, the image processing unit 91 processes the second image obtained from the second camera device 60 to obtain the printing position, shape, and size of the printed pattern (for example, text or mark) printed on the tablet T. The image processing unit 91 sends the information on whether the tablet T has cracks, notches, or dirt, the position information of each tablet T in the X direction, Y direction, and θ direction, and the printing position information, shape information, and size information of the printed pattern on each tablet T to the control unit 93.

[0064] The storage unit 92 stores processing information or various programs. For example, it is realized by a semiconductor memory element such as a random access memory (RAM) or a flash memory or a storage device such as a hard disk or an optical disk. The storage unit 92 stores data on the type of tablet T to be printed, data on the ink used in printing, printing data related to printing, and moving speed data of the conveyor belt 21. The printing data includes information on a printing pattern such as text or a mark.

[0065] The control unit 93 is a computer such as a central processing unit (CPU) or a microprocessor (MPU), and controls each unit. For example, the control unit 93 controls the supply device 10 or the conveying device 20, the detection device 30, the first camera device 40, the printing device 50, the second camera device 60, the recovery device 70, the maintenance device 80, the image processing unit 91, the storage unit 92, etc. based on various information or various programs stored in the storage unit 92. In addition, the control unit 93 receives a detection signal sent from the detection device 30 or the position detector 25. In addition, the control unit 93 is implemented by one or both of hardware and software, for example.

[0066] For example, the control unit 93 obtains the position of the tablet T on the conveyor 21 in the X direction based on the detection information sent from the detection device 30, that is, the timing of detecting the tablet T on the conveyor 21, and sets the imaging timing of the first imaging device 40, the printing start timing of the printing head 51 of the printing device 50, and the imaging timing of the second imaging device 60 based on the position information indicating the position of the tablet T in the X direction, and generates timing information indicating these timings and stores them in the storage unit 92. The so-called printing start timing refers to the timing of starting printing for the tablet T that has reached the printing position directly below the printing head 51. In addition, the control unit 93 can obtain information such as the movement amount (rotation amount) or speed of the conveyor 21 based on the detection information sent from the position detector 25.

[0067] In addition, the control unit 93 sets whether or not the tablet T having the information on cracks, notches, or dirt sent from the image processing unit 91 can be printed. Furthermore, the control unit 93 sets printing conditions for the tablet T set to be printable. At this time, the control unit 93 sets printing conditions for the tablet T having the position information based on the position information of the tablet T in the X direction, the Y direction, and the θ direction sent from the image processing unit 91. For example, the control unit 93 determines the range of the nozzles 51a used in the printing of the target tablet T in the print head 51, that is, the nozzle range, based on the position information of the tablet T in the Y direction or the printing data, and sets printing conditions including the nozzle range or the printing start timing. In addition, in the case where the tablet T has a directional shape, the control unit 93 sets the printing conditions corresponding to the position of the tablet T in the θ direction based on the position information of the tablet T in the θ direction. As an example, the control unit 93 registers 180 printing patterns obtained by rotating the orientation of the printing pattern by one degree at a time within the range of 0 degrees to 179 degrees into the storage unit 92, and selects a printing pattern with an angle suitable for the position of the tablet T in the θ direction from these printing patterns to set the printing conditions.

[0068] In addition, the control unit 93 determines whether the printed pattern is printed at a predetermined position on the tablet T in a predetermined shape and predetermined size, that is, determines whether the printed pattern is normally printed on the tablet T (printing state inspection) based on the printing position information, shape information, and size information of the printed pattern printed on the tablet T sent from the image processing unit 91. For example, when determining the shape and size of the printed pattern, the control unit 93 registers the inspection printed pattern in the storage unit 92, and compares the inspection printed pattern with the printed pattern on the actual printed tablet T (printed pattern printed on the tablet T).

[0069] In addition, the control unit 93 is suitable for storing various information (for example, information on whether the tablet T has cracks or notches, dirt, or position information, timing information, printing conditions, printing quality information, etc.) in the storage unit 92, but when the target tablet T is recovered by the recovery device 70, for example, at the time point after the end of the downstream side of the conveying direction H1 in the conveying device 20 falls and a predetermined time (for example, several seconds) has passed, the various information is deleted from the storage unit 92. However, in the case where this information is needed in subsequent processes, etc., the various information of each tablet T may be retained without being deleted, or stored in a storage medium outside the device. In the case of pre-saving various information of each tablet T, the information can be stored in association with the manufacturing date and time or the batch number, so that for the printed tablet T, the cause can be traced back to the situation where defective products are produced after leaving the factory.

[0070] (Configuration example of maintenance device)

[0071] Next, refer to Figure 3 The structure of the maintenance device 80 will be described. Figure 3 1 is a diagram of the print head 51 and the maintenance device 80 viewed from the upstream side of the conveying direction H1. As described above, the maintenance device 80 includes a liquid receiving portion 81, a suction portion 82, an eraser 83, and a moving mechanism 84. When not performing maintenance, they are positioned in the order of the eraser 83, the suction portion 82, and the liquid receiving portion 81 from the print head 51 side, and are arranged to be movable as a whole by the moving mechanism 84.

[0072] The liquid receiving portion 81 is formed, for example, in a box shape with an upper opening. During maintenance of the print head 51, the liquid receiving portion 81 receives ink ejected from each nozzle 51a of the opposite print head 51. The length of the liquid receiving portion 81 in a direction perpendicular to the conveying direction H1 is set to be at least longer than the nozzle row formed by arranging the nozzles 51a. In the first embodiment, the length of the liquid receiving portion 81 in a direction perpendicular to the conveying direction H1 is longer than two print heads 51 arranged side by side (longer than two print heads).

[0073] The suction unit 82 is a vacuum eraser having a slit-shaped suction port extending in the conveying direction H1 at the upper portion. The length of the slit-shaped suction port is substantially the same as the length of the print head 51 in the conveying direction H1. The suction unit 82 is connected to a suction pump (not shown). While the suction pump is operating, the suction unit 82 moves in a manner of scanning the nozzle surface while approaching the nozzle surface of the print head 51, thereby sucking and removing the ink attached to the nozzle surface.

[0074] The eraser 83 slides while being in contact with the nozzle surface of the print head 51, thereby wiping and removing the powder or ink adhering to the nozzle surface. The eraser 83 includes a first eraser 83a and a second eraser 83b.

[0075] The first eraser 83a has a liquid-absorbent fiber material such as nonwoven fabric on the upper part. The first eraser 83a is impregnated with an wiping liquid (for example, an aqueous solution containing ethanol). That is, the first eraser 83a is a wet eraser. In addition, the supply of the wiping liquid to the first eraser 83a can be performed by an operator or can be automatically supplied. By being supplied with the wiping liquid, the first eraser 83a is impregnated with the wiping liquid.

[0076] The second eraser 83b has a liquid-absorbent fiber material such as nonwoven fabric on the upper portion, similarly to the first eraser 83a. The second eraser 83b is a dry eraser that is dry (not supplied with an erasing liquid).

[0077] The moving mechanism 84 has a ball screw 84a, a slider 84b, and a motor 84c. The liquid receiving portion 81, the suction portion 82, and the eraser 83 are fixed to the slider 84b, and can be moved to a maintenance position and a standby position by rotating the ball screw 84a with the motor 84c. Here, the so-called maintenance position refers to the position of the maintenance device 80 when the print head 51 is maintained, and is a position between the conveyor belt 21 and the print head 51. In addition, the so-called standby position refers to the position of the maintenance device 80 when no maintenance is performed, and is a position deviated from the top of the conveyor belt 21 ( Figure 1 on the inside of the paper).

[0078] (Printing process)

[0079] Next, refer to Figure 1 and Figure 2 The printing process performed by the tablet printing device 1 is described. The printing process also includes an inspection process. Here, the printing process refers to the continuous printing of a plurality of tablets T supplied from the supply device 10 and conveyed by the conveying device 20. In addition, various information such as data required for printing is pre-stored in the storage unit 92.

[0080] When the tablet printing device 1 starts printing processing under the control of the control unit 93, the motor 24 is driven, and the conveyor belt 21 rotates in the conveying direction H1 along with the rotation of the drive pulley 22 caused by the motor 24. In the state where the conveyor belt 21 rotates in the conveying direction H1, the tablets T are sequentially supplied from the hopper 11 to the chute 12, and are supplied to the conveyor belt 21 in two rows through the chute 12. The tablets T supplied to the conveyor belt 21 are conveyed in two rows on the conveyor belt 21 at a predetermined moving speed.

[0081] The tablets T on the conveyor belt 21 are detected by the detection device 30. Specifically, when the tablets T on the conveyor belt 21 arrive at the laser light irradiation position of the detection unit 31 of the detection device 30, the detection unit 31 detects the arrival of the tablets T based on the change in the received light power. Based on the timing of the detection of the tablets T, the position of the tablets T in the X direction on the conveyor belt 21 is identified by the control unit 93. Then, the position information indicating the position of the tablets T in the X direction is generated by the control unit 93 and stored in the storage unit 92.

[0082] Next, the first camera 40 captures the tablet T on the conveyor 21. Specifically, the tablet T on the conveyor 21 is captured by the first camera 40 when it reaches the capturing position directly below the first camera 40, and the first image captured by the first camera 40 is sent to the control device 90. Based on the first image, the image processing unit 91 generates information on the presence or absence of cracks, notches, or dirt on the tablet T, and position information of the tablet T in the X direction, Y direction, and θ direction, and stores the information in the storage unit 92. Based on the information on the presence or absence of cracks, notches, or dirt on the tablet T, it is set whether or not printing can be performed on the target tablet T. In addition, based on the position information of the tablet T in the X direction, Y direction, and θ direction or the information of the printing pattern, the storage unit 92 sets the printing conditions, including the nozzle range to be used or the printing start timing for the tablet T set to be printable (printable tablet T). Furthermore, based on the printing start timing (the timing for starting printing on the tablet T), the ejection timing for the tablet T (the timing for ejecting ink on the tablet T) is determined.

[0083] Based on the printing conditions, printing is performed by the printing device 50. That is, the printing head 51 of the printing device 50 is controlled by the control unit 93 to print a specified printing pattern on the printable tablet T on the conveyor belt 21. In detail, at the printing start timing when the printable tablet T on the conveyor belt 21 that has passed under the first camera device 40 reaches the printing position directly below the printing head 51, printing is performed by the printing head 51 based on the printing conditions. In the printing head 51, ink is appropriately ejected from each nozzle 51a to print a printing pattern (for example, numbers, letters, katakana, symbols, graphics) on the upper surface of the tablet T, that is, the printed surface. The ink applied to the tablet T is dried during the conveyance process. In addition, a drying section (not shown) that uses gas or heat for drying may also be provided, and the ink is dried by the drying section.

[0084] Thereafter, the second imaging device 60 captures the printed tablet T on the conveyor belt 21. Specifically, the second imaging device 60 captures the printed tablet T on the conveyor belt 21 when the tablet T reaches the imaging position directly below the second imaging device 60, and the second image captured by the second imaging device 60 is sent to the control device 90.

[0085] The second image is analyzed by the image processing unit 91 of the control device 90. Specifically, the image processing unit 91 acquires information related to the printed pattern printed on the tablet T, that is, the printing position, shape, and size of the printed pattern. The image processing unit 91 analyzes the second image sent from the second imaging device 60, generates inspection information indicating the printing position, shape, and size of the printed pattern printed on the tablet T, and stores the information in the storage unit 92.

[0086] Based on the inspection information, the control unit 93 performs a printing state inspection. Specifically, based on the inspection information related to the printing position, shape, and size stored in the storage unit 92, the control unit 93 determines whether the printing pattern is normally printed on the tablet T, generates printing quality information indicating whether the printing of the tablet T is good, and stores it in the storage unit 92. For example, in the printing state inspection, the printing pattern used in printing is stored in the storage unit 92 as a printing pattern for inspection, and the quality information related to the prescribed printing position, shape, and size of the printing pattern for inspection is compared with the inspection information related to the printing position, shape, and size of the printing pattern actually printed and stored in the storage unit 92 to determine whether the printing pattern is normally printed on the tablet T (qualified or unqualified).

[0087] Finally, the tablets T on the conveyor belt 21 are recovered by the recovery device 70. Specifically, when the inspected tablets T are located at the end of the downstream side of the conveyor belt 21 as the conveyor belt 21 moves, they are released from the state of being held on the conveyor belt 21, fall from the conveyor belt 21, and are recovered by the recovery device 70. At this time, the tablets T that are qualified tablets fall directly and are recovered as qualified products by the recovery device 70, but the tablets T that are unqualified tablets or non-printed tablets are separated from qualified products by air blowing in the middle of falling from the conveyor belt 21 and are recovered as defective products by the recovery device 70.

[0088] (Maintenance process)

[0089] During the printing operation of such a printing process, maintenance of the print head 51 is performed at a predetermined timing. Maintenance methods include cleaning, wiping, and virtual ejection. The so-called cleaning refers to the action of ejecting ink from the print head 51 toward the liquid receiving portion 81 by pressurizing the ink while the liquid receiving portion 81 and the print head 51 are facing each other. By performing the cleaning action, bubbles or ink that has been dried, thickened, or solidified can be removed from the nozzle 51a, thereby preventing poor ejection. The so-called wiping refers to the removal of ink or the like attached to the nozzle surface of the print head 51. Erasing is performed by suctioning with the suction portion 82 or wiping with the eraser 83. By wiping, powder or ink attached to the nozzle surface can be removed, thereby preventing poor ejection. The so-called virtual ejection refers to the action of driving the inkjet drive element to eject a small amount of ink while the liquid receiving portion 81 and the print head 51 are facing each other (pre-ejection action). The thickened ink can also be removed from the nozzle 51a by virtual ejection. The printing operation refers to a state in which the tablet printing apparatus 1 is in operation, that is, a state in which printing can be performed, including a printing process and a maintenance process.

[0090] For example, there are various types of tablets T, such as uncoated tablets, OD tablets (orally disintegrating tablets), and coated tablets (sugar-coated tablets or film-coated tablets, etc.). Moreover, the amount of fine powder that can be separated from the tablet T varies depending on the type of tablet T. Therefore, the amount of fine powder of the tablet T that can be attached to the nozzle surface of the print head 51 varies depending on the type of tablet T. That is, even if the tablets T are printed at the same time or in the same quantity, the amount of fine powder attached to the nozzle surface of the print head 51 varies. In other words, the degree of contamination of the nozzle surface by the fine powder varies.

[0091] Therefore, in the present embodiment, the timing of the maintenance performed by the maintenance device 80 in the printing process is set based on the type of tablet T. More specifically, the timing of the maintenance is set so that the interval of the maintenance performed by the maintenance device 80 in the printing process for printing the tablet T that is not easy to generate fine powder is longer than that in the printing process for printing the tablet T that is easy to generate fine powder. For example, when the tablet T supplied from the supply device 10 is any one of a coated tablet, a non-coated tablet, and an orally disintegrating tablet, the timing is set so that the interval of the maintenance performed by the maintenance device 80 is longer in the case of a non-coated tablet than in the case of an orally disintegrating tablet, and the interval of the maintenance performed by the maintenance device 80 is longer in the case of a coated tablet than in the case of a non-coated tablet.

[0092] The details of this maintenance process are described. First, information related to the type of tablet T and the timing of maintenance performed in the printing process of the tablet T of this type is pre-stored in the storage unit 92 of the control device 90. For example, if the types of tablets T are set to three types: coated tablets, uncoated tablets, and orally disintegrating tablets, the timing S1 of maintenance for coated tablets, the timing S2 of maintenance for uncoated tablets, and the timing S3 of maintenance for orally disintegrating tablets are stored respectively. In addition, the timing S1, timing S2, and timing S3 are the time from the execution of this maintenance to the execution of the next maintenance, and the relationship between them is S1>S2>S3. These timings S1, S2, and S3 can be obtained by performing a printing process on each tablet T and observing the contamination caused by the attachment of fine powder to the nozzle surface of the printing head 51.

[0093] When the printing process is executed, the type of tablet T to be printed in the current printing process is input and stored in advance in the storage unit 92 of the control device 90. In the printing process, the control device 90 performs maintenance at a timing corresponding to the type of tablet T stored in the storage unit 92. For example, when the type of tablet T stored in the storage unit 92 is a non-coat piece, the control device 90 causes the maintenance device 80 to perform maintenance at a timing S2 corresponding to the non-coat piece.

[0094] The operation of the maintenance is as follows: During the maintenance process, the supply of the tablets T by the supply device 10 is temporarily stopped.

[0095] When the timing for maintenance of the print head 51 is reached, the control device 90 controls the lifting mechanism 52 to raise the print head 51. More specifically, the print head 51 is raised to a height position where the lower surface of the print head 51 does not contact the suction unit 82 and the eraser 83 even when the suction unit 82 and the eraser 83 of the maintenance device 80 are moved. Thus, a space is formed between the conveyor belt 21 and the print head 51 into which the maintenance device 80 can enter.

[0096] Next, the control device 90 controls the moving mechanism 84 to position the liquid receiving portion 81 to face the nozzle surface of the printing head 51. Furthermore, the lifting mechanism 52 is controlled, such as Figure 5 As shown, the print head 51 is lowered to a height at which the nozzle surface of the print head 51 does not abut against the suction portion 82 but abuts against the eraser 83 when erasing is performed.

[0097] In this state, the control device 90 performs a purge operation by pressure feeding the ink in the print head 51 .

[0098] Next, the control device 90 controls the moving mechanism 84 to move the suction unit 82 and the eraser 83 to the Figure 5During this movement, the print head 51 is sequentially subjected to vacuum erasure by the suction unit 82, wet erasure by the first eraser 83a, and dry erasure by the second eraser 83b.

[0099] When these erasures are completed, the control device 90 controls the lifting mechanism 52 to raise the print head 51 to a height position where it does not contact the suction unit 82 or the eraser 83. When the rise of the print head 51 is completed, the moving mechanism 84 is controlled to position the liquid receiving unit 81 to face the nozzle surface of the print head 51. Then, with the liquid receiving unit 81 facing the nozzle surface of the print head 51, the print head 51 performs a virtual ejection.

[0100] When the virtual ejection is completed, the control device 90 controls the moving mechanism 84 to move the maintenance device 80 (the suction unit 82 and the eraser 83) to the standby position. Then, the lifting mechanism 52 is controlled to lower the printing head 51 to a height position for printing the tablets T. When the printing head 51 is lowered, the maintenance process is completed. After the maintenance process is completed, the supply of tablets T using the supply device 10 is restarted, and the printing process of printing on the tablets T is performed. In addition, as maintenance actions, examples of performing a clearing action, vacuum erasing, wet erasing, dry erasing, and virtual ejection are described, but not all of the above actions must be performed, and the order in which they are performed can also be set arbitrarily. For example, the processing and order performed as maintenance actions can also be set for each type of tablet T.

[0101] In addition, the maintenance process performed during the printing process has been described. However, there may be a situation where the printing process is not performed for several hours due to some reasons even though the printing operation is in progress. For example, when parts are clogged in the supply device 10 during long hours of unmanned operation such as during night operation, the tablets T may not be supplied for several hours before the operator performs repair work. In this case, the print head 51 is in a standby state so that printing can be performed when the supply of tablets T is restarted.

[0102] In the present embodiment, corresponding to this situation, the timing S4 of maintenance during the period when the supply of tablets T from the supply device 10 is stopped during the printing operation is stored in the storage unit 92. During the period when the supply of tablets T is stopped, no fine powder from the tablets T is generated. Therefore, compared with the printing process, there is almost no adhesion of fine powder to the nozzle surface of the printing head 51. Therefore, the timing of maintenance does not need to consider the contamination of the nozzle surface caused by the adhesion of fine powder, but mainly considers the increase in ink viscosity caused by the drying of ink in the nozzle 51a. Therefore, the timing S4 is set to a value greater than any of the timings S1, S2, and S3 set in the printing process. That is, it is set in a manner that the maintenance interval becomes longer.

[0103] Thus, when the supply of tablets T from the supply device 10 stops during printing operation, the control device 90 performs maintenance of the print head 51 at the timing S4 set to be longer than the interval of maintenance performed in the printing process.

[0104] In addition, when the supply of tablets T is stopped for a long time, the driving of the conveying device 20 may be stopped. More specifically, the rotation of the conveying belt 21 may be stopped and the decompression in the suction chamber 26 may be stopped. In this case, in addition to the fact that there is almost no adhesion of fine powder to the nozzle surface as described above, the airflow around the nozzle surface of the printing head 51 also becomes weak. That is, the generation of airflow accompanying the rotation of the conveying belt 21 disappears, and the suction from the suction hole 21a of the conveying belt 21 disappears, so there is no airflow generated around the nozzle surface caused by them. If the airflow around the nozzle surface is weakened, the replacement of air near the opening of the nozzle 51a becomes slow, so it is easy to maintain the solvent environment of the ink near the opening of the nozzle 51a, suppress the drying of the ink in the nozzle 51a, and suppress the viscosity increase of the ink caused by drying. Therefore, in this case, the maintenance timing S4 is set so that the maintenance interval becomes longer than when only the supply of tablets T from the supply device 10 is stopped. For example, when the timing of maintenance when only the supply of tablets T from the supply device 10 stops is set to S4a, the timing of maintenance when the drive of the conveying device 20 also stops in addition to the supply of tablets T from the supply device 10 stopping is set to timing S4b where the frequency of maintenance becomes lower (i.e., the interval between maintenance becomes longer) compared to timing S4a.

[0105] Thus, when the supply of tablets T from the supply device 10 stops and the drive of the conveying device 20 stops although printing is in progress, the control device 90 performs maintenance of the print head 51 at timing S4b which is set in such a way that the maintenance interval becomes longer than the maintenance interval when only the supply of tablets T from the supply device 10 stops.

[0106] In addition, the fact that the supply of tablets T from the supply device 10 has stopped can be known, for example, by the presence or absence of a detection signal from the detection device 30. That is, when the detection signal of tablets T from the detection device 30 is not output for a predetermined period of time even though the supply amount of tablets T from the supply device 10 does not reach the predetermined production number of tablets T (the number to be supplied from the supply device 10), it can be determined that the supply of tablets T from the supply device 10 has stopped.

[0107] As described above, according to the first embodiment, the tablet printing device 1 includes: a supply device 10 that accommodates a plurality of tablets T and sequentially supplies the accommodated tablets T; a conveying device 20 that conveys the tablets T supplied from the supply device 10; a printing head 51 that is an inkjet method and prints by ejecting ink droplets on the tablets T conveyed by the conveying device 20; a maintenance device 80 that performs maintenance on the printing head 51; and a control device 90 that controls the printing head 51 and the maintenance device 80. When the control device 90 performs printing on the tablets T, the maintenance device 80 performs maintenance at a timing set based on the type of tablets T supplied from the supply device 10. Thus, the tablets T can be stably printed while preventing a decrease in productivity. That is, according to the tablet printing device 1 of the first embodiment, when printing is performed on a type of tablet T that requires an increased maintenance frequency of the printing head 51, the maintenance timing can be set so that the maintenance interval is shortened compared to when printing is performed on a type of tablet T that does not require an increased maintenance frequency of the printing head 51. Therefore, it is possible to prevent maintenance from being performed more frequently than necessary when printing is performed on a type of tablet T that does not require an increase in the maintenance frequency of the print head 51. When printing is performed on a type of tablet T that requires an increase in the maintenance frequency, the print head 51 can be maintained at an appropriate timing. As a result, tablets T can be stably printed while preventing a decrease in productivity.

[0108] In addition, in the first embodiment, the maintenance timing is set so that the interval of maintenance by the maintenance device 80 becomes longer for the tablet T that is not easy to generate fine powder than for the tablet T that is easy to generate fine powder. Thus, for example, the maintenance timing can be set so that the interval of maintenance becomes shorter as the tablet T is easy to generate fine powder (the maintenance interval becomes longer as the tablet T is not easy to generate fine powder). Therefore, when printing is performed on a tablet T that is not easy to generate fine powder and thus the fine powder of the tablet T is not easy to adhere to the nozzle surface of the print head 51, the maintenance timing can be set so that the maintenance interval becomes longer than when printing is performed on a tablet T that is easy to generate fine powder and thus the fine powder of the tablet T is easy to adhere to the nozzle surface of the print head 51. As a result, it is possible to prevent maintenance from being performed more frequently than necessary when printing is performed on a tablet T that is not easy to adhere to the print head 51, and when printing is performed on either the tablet T that is easy to generate fine powder or the tablet T that is not easy to generate fine powder, the maintenance of the print head 51 can be performed at an appropriate timing. Thus, tablets T can be stably printed while preventing productivity from being reduced.

[0109] In the first embodiment, when any of the tablets T of the coated tablet, the uncoated tablet, and the orally disintegrating tablet is supplied from the supply device 10, the maintenance timing is set so that the interval of maintenance by the maintenance device 80 is longer in the case of the uncoated tablet than in the case of the orally disintegrating tablet, and the interval of maintenance by the maintenance device 80 is longer in the case of the coated tablet than in the case of the uncoated tablet. Generally speaking, the uncoated tablet is more likely to generate fine powder from the tablet T than the coated tablet, and the orally disintegrating tablet is more likely to generate fine powder from the tablet T than the uncoated tablet. Therefore, by setting the maintenance timing as described above, the more fine powder is generated from the tablet T, the higher the maintenance frequency of the print head 51 is, and the less fine powder is generated from the tablet T, the lower the maintenance frequency of the print head 51 is. As a result, it is possible to prevent the maintenance of the print head 51 from being performed more frequently than necessary when printing is performed on the tablet T on which fine powder is less likely to adhere to the nozzle surface of the print head 51, and when printing is performed on the tablet T on which fine powder is more likely to adhere to the nozzle surface of the print head 51, the maintenance of the print head 51 can be performed at an appropriate timing. Thus, the tablets T can be stably printed while preventing a decrease in productivity.

[0110] In addition, in the first embodiment, during the period when the tablets T are stopped from the supply device 10, the maintenance timing is set so that the interval of maintenance by the maintenance device 80 becomes longer than when printing is performed on the tablets T. This can prevent the print head 51 in the standby state from being maintained more frequently than necessary when the print head 51 is in the standby state without the tablets T being supplied from the supply device 10. As a result, in addition to the above-mentioned effects, the stable ejection from the nozzle 51a of the print head 51 can be maintained, and the consumption of ink accompanying maintenance can be suppressed.

[0111] In the first embodiment, the conveying device 20 includes: a conveying belt 21 having a plurality of suction holes 21a; and a suction unit that causes negative pressure to act on the suction holes 21a so that the suction holes 21a suck and hold the tablets T, and the control device 90 sets the timing of maintenance in such a way that the interval of maintenance by the maintenance device 80 becomes the longest during the period when the supply of tablets T from the supply device 10 is stopped and the suction unit is stopped. Thus, when the print head 51 is in a standby state in a state where the ink in the nozzle 51a of the print head 51 is not easily thickened, etc., the timing of maintenance can be set in such a way that the interval of maintenance becomes longer than the above. As a result, the consumption of ink accompanying maintenance can be further suppressed.

[0112] <Second embodiment>

[0113] In this embodiment, the same components as those in the first embodiment will be described using the same reference numerals.

[0114] In addition, when printing a tablet that is easy to generate powder, such as a non-coated tablet, powder may be generated, and the generated powder may adhere to the nozzle surface. Usually, in the nozzle 51a of the inkjet printing head 51, the ink filled in the nozzle 51a is adjusted to form a concave surface through a meniscus at the ejection outlet by the water level difference of the ink container connected to the printing head 51. Therefore, when cleaning, a part of the ink squeezed out from the nozzle 51a forms a meniscus again, so that the powder attached to the ejection outlet and the surrounding of the ejection outlet of the nozzle 51a is collected in the nozzle 51a. Therefore, the nozzle 51a is clogged, which sometimes causes poor ejection.

[0115] Therefore, when the tablet T to be printed is a tablet that easily generates powder like a tablet without a coating, in the maintenance of the print head 51, wiping is performed before cleaning (before the ejection operation) to remove the powder attached to the nozzle surface. That is, cleaning is performed after wiping, and then wiping is performed. The maintenance process of the print head 51 when the tablet T to be printed is a tablet without a coating is described below.

[0116] like Figure 6As shown, the second eraser 83b in this embodiment has a liquid-absorbent fiber material such as non-woven fabric on the upper part, similarly to the first eraser 83a. The second eraser 83b is a dry eraser (not supplied with wiping liquid). The suction nozzle 82a is connected to the suction pump 82c described above via the pipe 82b. The second eraser 83b is provided with a suction nozzle 82a, and a suction force can be applied to its surface. The pipe 82b branches off midway and is connected to the suction section 82. A switching valve 82d and a switching valve 82e are provided in the pipe 82b. By switching them, it is possible to switch whether or not the suction force from the suction pump 82c is applied to the suction section 82, and it is also possible to switch whether or not the suction force from the suction pump 82c is applied to the suction nozzle 82a.

[0117] The maintenance process of the print head 51 is shown in FIG. Figure 7 . Figure 7 The processing shown is executed by each unit under the control of the control device 90. The type of tablet T to be printed is input by the operator via the input device 90a in advance when the printing operation is started, and is stored in the storage unit 92. During the maintenance process, the supply of tablets T by the supply device 10 is temporarily stopped.

[0118] When the maintenance time of the print head 51 is reached, the lifting mechanism 52 is controlled to raise the print head 51 (step S101). As a result, the distance between the conveyor belt 21 and the print head 51 increases. At this time, the print head 51 rises to a height position where the lower surface of the print head 51 does not contact the suction unit 82 and the eraser 83 even if the suction unit 82 and the eraser 83 are moved as described later.

[0119] Next, the moving mechanism 84 is controlled so that the liquid receiving portion 81 is positioned to face the nozzle surface of the printing head 51. Furthermore, the lifting mechanism 52 is controlled so that Figure 5 As shown, the print head 51 is lowered to a height at which the nozzle surface of the print head 51 does not abut against the suction portion 82 but abuts against the eraser 83 when erasing (step S102).

[0120] The moving mechanism 84 is controlled so that the suction unit 82 and the eraser 83 are moved toward Figure 5 Thus, the print head 51 is sequentially subjected to vacuum erasure by the suction unit 82, wet erasure by the first eraser 83a, and dry erasure by the second eraser 83b (step S103). The above erasures can remove the powder attached to the nozzle surface of the print head 51.

[0121] At this time, in order to apply the suction force from the suction pump 82c only to the suction portion 82, the switching valve 82d is closed and the switching valve 82e is opened.

[0122] When the first erasing is completed, the lifting mechanism 52 is controlled to raise the print head 51 (step S104). When the print head 51 is raised, the moving mechanism 84 is controlled so that the liquid receiving portion 81 is positioned to face the nozzle surface of the print head 51. Figure 5 As shown, the print head 51 is lowered to a height at which the nozzle surface of the print head 51 contacts the eraser 83 when erasing (step S105).

[0123] Thereafter, the ink in the print head 51 is pressure-fed to perform a purge operation (step S106 ).

[0124] Next, the second erasing is performed. The moving mechanism 84 is controlled so that the suction unit 82 and the eraser 83 are moved toward Figure 5 Thus, the print head 51 is subjected to vacuum erasure by the suction unit 82, wet erasure by the first eraser 83a, and dry erasure by the second eraser 83b in sequence (step S107). The second erasure is the same as the first erasure in step S103 described above.

[0125] After the second erasing is completed, the lifting mechanism 52 is controlled to raise the print head 51 (step S108). When the print head 51 is raised, the moving mechanism 84 is controlled to position the liquid receiving portion 81 to face the nozzle surface of the print head 51 (step S109). In the state where the liquid receiving portion 81 faces the nozzle surface of the print head 51, the inkjet drive element of the print head 51 is driven, thereby performing virtual ejection (step S110).

[0126] After the virtual ejection is completed, the moving mechanism 84 is controlled to move the maintenance device 80 (the suction unit 82 and the eraser 83) to the standby position (step S111), and the lifting mechanism 52 is controlled to lower the printing head 51 to a height position for printing operation (step S112). After the printing head 51 is lowered, the maintenance process is completed. After the maintenance process is completed, the supply of tablets T by the supply device 10 is restarted, and the printing operation is performed.

[0127] (Eraser maintenance process)

[0128] In this way, when the tablet T to be printed is a tablet that generates a large amount of powder like a non-coated tablet, when the print head 51 is regularly maintained, the first erasing is first performed to remove the powder, and the second erasing is performed after the cleaning. If so, each time the erasing is repeated, the first eraser 83a gradually dries up and the moisture retention capacity decreases, and the second eraser 83b gradually becomes wet and the liquid absorption efficiency deteriorates. Therefore, the eraser 83 needs to be maintained.

[0129] Here, the mechanism for maintaining the eraser 83 is referred to as an eraser maintenance mechanism, and the eraser maintenance mechanism includes a suction nozzle 82a, a pipe 82b, a suction pump 82c, a switching valve 82d, a switching valve 82e, a groove S described later, and a bellows portion 83a1 (all refer to Figure 8 ).

[0130] The control unit 93 determines whether the maintenance frequency has reached a predetermined frequency. When it is determined that the predetermined frequency has been reached, the control unit 93 displays a warning on a display device (not shown) that the erasing liquid is supplied to the first erasing device 83a. As a result, the operator supplies additional erasing liquid to the first erasing device 83a. When the supply is completed, the operator presses a button provided on the display device, and the control unit 93 receives this operation and determines that the maintenance of the first erasing device 83a is completed.

[0131] Furthermore, when the control unit 93 determines that the number of maintenance times has reached a predetermined number of times, the switching valve 82d is opened and the switching valve 82e is closed so that the suction force from the suction pump 82c acts on the suction nozzle 82a. In this way, the excess liquid that has penetrated into the second eraser 83b is sucked and dried by the suction nozzle 82a. The setting position of the suction nozzle 82a can be a position facing the second eraser 83b and the liquid held by the second eraser 83b can be sucked by the suction force from the suction pump 82c. Since the suction nozzle 82a itself moves with the second eraser 83b, it is ideally set at a position lower than the nozzle surface of the print head 51 to avoid contact with the nozzle surface. The maintenance of the second eraser 83b is implemented in parallel with the maintenance of the first eraser 83a. When the suction of the second eraser 83b is performed for a predetermined time, the control unit 93 determines that the maintenance of the second eraser 83b is completed.

[0132] In addition, the prescribed number of maintenance can be set by finding out in advance through experiments, etc., whichever is earlier, the timing when the first eraser 83a dries up and cannot wipe the powder or ink attached to the nozzle surface of the print head 51, or the timing when the liquid absorption efficiency of the second eraser 83b decreases and cannot absorb the liquid (ink or wiping liquid) attached to the nozzle surface of the print head 51. Depending on the type of tablet T, the ink used is different. When the percentage of volatile solvents such as ethanol contained in the ink is low, there is a tendency that the time until the liquid absorption efficiency of the second eraser 83b decreases becomes shorter. Therefore, the prescribed number of times is preferably found through experiments, etc. for each type of ink used for the tablet T. In addition, the timing of maintenance of the first eraser 83a and the second eraser 83b may not be simultaneous. In this case, regarding the prescribed number of maintenance times, the time required for maintenance of the first eraser 83a and the second eraser 83b is calculated (as described above, the time when the first eraser 83a dries up and cannot wipe off the powder or ink attached to the nozzle surface of the print head 51, and the time when the liquid absorption efficiency of the second eraser 83b decreases and cannot absorb the liquid attached to the nozzle surface of the print head 51), and each is used as the prescribed number of maintenance times.

[0133] When the control unit 93 determines that the maintenance of the first eraser 83 a and the second eraser 83 b is completed, the control unit 93 restarts the printing process.

[0134] By performing such a maintenance process of the eraser 83, the eraser 83 can be continuously used without replacement, thereby reducing costs.

[0135] In addition, the eraser 83 may be a roller-shaped eraser including an axis in a direction perpendicular to the direction in which the nozzles 51a are arranged. In this case, the eraser 83 can be rotated at the time of completing the maintenance of the eraser 83 so that the portion with the most eraser liquid attached to the first eraser 83a and the driest portion of the second eraser 83b are positioned facing the nozzle surface.

[0136] In addition, although the case where the operator supplies the erasing liquid to the first erasing device 83a is exemplified, a predetermined amount may be automatically supplied by a supply nozzle (not shown).

[0137] In addition, if Figure 8As shown, the first eraser 83a may also be configured to always supply the erasing liquid. That is, the bellows portion 83a1, which is a part of the first eraser 83a, is made to hang down and immersed in the tank S storing the erasing liquid. Since the raw material of the first eraser 83a is a non-woven fabric or other liquid-absorbent fiber material, the erasing liquid in the tank S is supplied to the first eraser 83a along the bellows portion 83a1 by the capillary phenomenon. When such a structure is provided, it may be configured to perform maintenance of only the second eraser 83b in the maintenance process of the eraser 83 described above. Alternatively, it may be configured to replenish the erasing liquid in the tank S or change the length of the bellows portion 83a1 in the maintenance process of the eraser 83. In addition, the lower part of the main body of the first eraser 83a may be immersed in the erasing liquid in the tank S.

[0138] In addition, the maintenance of the eraser 83 is performed when the maintenance process of the print head 51 reaches a predetermined number of times, but the present invention is not limited thereto, and the maintenance of the eraser 83 may be performed all the time in parallel during the printing process or the maintenance process of the print head 51. Figure 8 The method of the groove S shown in the figure allows the erasing liquid to be continuously supplied. In addition, for the second eraser 83b, the switching valve 82d is always in an open state and the suction nozzle 82a is always sucking the surface of the second eraser 83b. During the maintenance of the print head 51, the switching valve 82e is also in an open state, but the suction by the suction nozzle 82a may be performed in parallel without closing the switching valve 82d.

[0139] As described above, according to the second embodiment, the eraser 83 can be properly maintained, so the life of the eraser 83 can be extended and the replacement frequency of the eraser 83 can be reduced. This can reduce costs. In addition, the suction pump 82c used in the suction unit 82 is the same as the suction pump 82c that applies suction force to the suction nozzle 82a for drying the second eraser 83b, so that the limited space of the tablet printing device 1 can be effectively used.

[0140] In addition, when replacing the eraser 83, in order to contact and wipe the nozzle surface of the print head 51 with appropriate pressure, it is necessary to perform high-precision height adjustment, which takes time. During the time of replacing the eraser 83 and adjusting the height, the tablet printing device 1 needs to stop operating. According to this embodiment, the replacement frequency of the eraser 83 can be reduced, so the operation stop of the tablet printing device 1 caused by the replacement of the eraser 83 can be limited to a minimum, and the production efficiency can be improved.

[0141] <Other embodiments>

[0142] In the above description, two print heads 51 are provided, but one may be provided, or three or more may be provided. In addition, one maintenance device 80 may be provided for one print head 51 , or one maintenance device 80 may be shared by a plurality of print heads 51 .

[0143] In addition, although the case where the liquid receiving part 81, the suction part 82, and the wiper 83 move integrally is illustrated, the present invention is not limited thereto, and each of the liquid receiving part 81, the suction part 82, and the wiper 83 may be provided to be movable independently.

[0144] In addition, the example in which the eraser 83, the suction unit 82, and the liquid receiving unit 81 are moved toward the print head 51 by the moving mechanism 84 is shown, but the present invention is not limited to this. For example, the print head 51 may be moved, or both the print head 51 and the maintenance device 80 may be moved. In other words, it is sufficient as long as the print head 51 and the maintenance device 80 are relatively moved.

[0145] The second wiper 83 b may be any device as long as it can remove the wiper liquid (cleaning liquid) adhering to the nozzle surface, and may be, for example, a scraper.

[0146] In addition, the case where the information of the ink used in printing is input to the control device 90 by the operator via the input device 90a is illustrated, but the present invention is not limited to this. For example, the tablet printing device 1 may include a radio frequency (RF) tag reading unit, and when the ink container (bottle or box) is mounted on the tablet printing device 1, the ink information is obtained by reading the RF tag attached to the ink container. In addition, a barcode or a two-dimensional code may be mounted on the ink container, and the ink information may be input to the tablet printing device 1 by reading the barcode or the two-dimensional code.

[0147] In addition, although the case where the maintenance process is performed regularly during the printing operation is exemplified, the present invention is not limited thereto and the maintenance process may be performed when a discharge failure of the nozzle 51 a or a printing failure is detected based on the second image.

[0148] In addition, in the first embodiment, an example of setting the maintenance timing based on the type of tablet T is described, but it is not limited to this, and it can also be set based on the type of ink printed on the tablet T. For example, the ink becomes thicker due to drying. If the ink in the nozzle 51a becomes thicker, it is sometimes impossible to eject the ink from the nozzle 51a. Therefore, in the case where the ink in the nozzle 51a becomes thicker, it is necessary to perform maintenance such as discharging the ink in the nozzle 51a. On the other hand, the ink differs in the degree of ease of drying depending on its composition (type). Therefore, the timing of maintenance for discharging the thickened ink is different depending on the type of ink. Therefore, it is necessary to set the timing of maintenance based on the type of ink.

[0149] Furthermore, even for ink that dries easily, when the frequency of ink ejection from the nozzle 51a is relatively high, the ink in the nozzle 51a does not stay in the nozzle 51a for a long time, and is not likely to increase in viscosity. On the contrary, the ink in the nozzle 51a with a relatively low ejection frequency stays in the nozzle 51a for a longer time, and is therefore likely to increase in viscosity. Therefore, the timing of maintenance based on the type of ink is preferably set based on the nozzle 51a with a low ejection frequency in the print head 51. At this time, it is preferable to compare with the timing of maintenance set based on the type of tablet T, and set the timing of maintenance with a shorter maintenance interval.

[0150] In the maintenance process, the speed of erasing by the first eraser 83a and the second eraser 83b is not particularly described, but the moving speed of the first eraser 83a and the second eraser 83b (the speed at which the eraser 83 slides on the nozzle surface of the print head 51) can be controlled by controlling the moving mechanism 84. For example, the control unit 93 counts the number of erasing times of the print head 51 in advance, and when the number exceeds a predetermined number, the moving speed of the moving mechanism 84 is reduced to reduce the moving speed of the first eraser 83a and the second eraser 83b. Alternatively, the control unit 93 measures the time since the start of the operation of the tablet printing device 1, and determines that the number of erasing times by the eraser 83 exceeds the predetermined number when the predetermined time has passed, thereby reducing the moving speed of the moving mechanism 84 to reduce the moving speed of the first eraser 83a and the second eraser 83b. The nozzle surface of the print head 51 may also be fixed and accumulated with the increase of the operating time. However, by reducing the moving speed of the moving mechanism 84 by the control unit 93, the erasing liquid held in the first eraser 83a is sufficiently supplied to the nozzle surface of the print head 51, thereby appropriately removing the ink fixed on the nozzle surface. Not limited to when the erasing exceeds the prescribed number of times or when the prescribed time has passed, the control may be performed in the following manner: the speed is gradually reduced from the start of the tablet printing device 1. In addition, the erasing speed of only one of the first eraser 83a and the second eraser 83b may be reduced, and it may be set that the erasing liquid is sufficiently supplied to the nozzle surface of the print head 51 by reducing the moving speed of only the first eraser 83a, thereby removing the fixed ink. In this case, it is preferable that the first eraser 83a and the second eraser 83b are configured to be independently movable. For example, it may be configured such that one of the first eraser 83a and the second eraser 83b is moved by the moving mechanism 84 and the other of the first eraser 83a and the second eraser 83b is moved by a moving mechanism different from the moving mechanism 84 (in the same direction as the moving mechanism 84).

[0151] In the second embodiment, when the erasing liquid is automatically supplied to the first erasing device 83a, it is sufficient to provide an erasing liquid supply unit in the first erasing device 83a. If the erasing liquid supply unit is provided, the amount of the erasing liquid supplied to the first erasing device 83a can be changed by controlling the erasing liquid supply unit when the ink contains a fixing agent (for example, a substance classified as a paste or a gum base, a thickening stabilizer) and when the ink does not contain a fixing agent.

[0152] In addition, a wet state detection sensor for detecting the amount of the erasing liquid contained in the first eraser 83a (the wet state of the first eraser 83a) may be provided. The wet state detection sensor sends the detection value to the control device 90. The control device 90 may determine the wet state of the first eraser 83a based on the detection value sent from the wet state detection sensor. The control device 90 may be set to start the maintenance process of the eraser 83 based on the determination result.

[0153] In addition, the amount of the erasing liquid supplied to the first erasing device 83a can also be adjusted according to the composition of the ink, for example, according to the type or content of the fixing agent.

[0154] In the maintenance process of the print head 51, the speed of erasing by the first eraser 83a and the second eraser 83b is not particularly described, but it can be set as: by controlling the moving mechanism 84, the moving speed of the first eraser 83a and the second eraser 83b (the speed at which the eraser 83 slides on the nozzle surface of the print head 51) is controlled. For example, it can be set as: the control unit 93 counts the number of erasing times of the print head 51 in advance, and when it exceeds a predetermined number, the moving speed of the moving mechanism 84 is reduced to reduce the moving speed of the first eraser 83a and the second eraser 83b. Alternatively, it can be set as: the control unit 93 measures the time since the operation of the tablet printing device 1 started, and determines that the number of erasing times by the eraser 83 exceeds the predetermined number of times when the predetermined time has passed, thereby reducing the moving speed of the moving mechanism 84 to reduce the moving speed of the first eraser 83a and the second eraser 83b. There is also a case where the ink is fixed and accumulated on the nozzle surface of the print head 51 as the operation time becomes longer. However, by reducing the moving speed of the moving mechanism 84 by the control unit 93, the erasing liquid held in the first eraser 83a is sufficiently supplied to the nozzle surface of the print head 51, thereby appropriately removing the ink fixed on the nozzle surface. Not limited to when the erasing exceeds the prescribed number of times or when the prescribed time has passed, the control may be performed in the following manner: the speed is gradually reduced from the start of the tablet printing device 1. In addition, the erasing speed of only one of the first eraser 83a and the second eraser 83b may be reduced, and it may be set that the erasing liquid is sufficiently supplied to the nozzle surface of the print head 51 by reducing the moving speed of only the first eraser 83a, thereby removing the fixed ink. In this case, it is preferable that the first eraser 83a and the second eraser 83b are configured to be independently movable. For example, one of the first eraser 83a and the second eraser 83b may be moved by the moving mechanism 84, and the other of the first eraser 83a and the second eraser 83b may be moved by a moving mechanism different from the moving mechanism 84 (in the same direction as the moving mechanism 84). In addition, the eraser 83 may be maintained at this timing.

[0155] In addition, during the maintenance of the second eraser 83b, it is also possible to consider drying by spraying a drying gas onto the surface of the second eraser 83b. However, sometimes the nozzle surface of the print head 51 is dried by the blown drying gas, and the ink of the nozzle 51a solidifies, resulting in poor printing. Therefore, the most suitable is the drying performed by the suction nozzle 82a described above. It is also possible to blow the drying gas in parallel with the drying performed by the suction nozzle 82a, but in this case, it is preferred to blow the drying gas in a direction away from the nozzle surface of the print head 51 to prevent the nozzle 51a from drying.

[0156] Here, as the tablet T, tablets used for medical purposes, dietary purposes, cleaning purposes, industrial purposes or aromatic purposes may be included. In addition, as the tablet T, there are bare tablets (uncoated tablets) or sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multilayer tablets, core tablets, etc., and various capsule tablets such as hard capsules or soft capsules may also be included in the tablet T. Furthermore, as the shape of the tablet T, there are various shapes such as disc or lens, triangle, and ellipse. In addition, in the case where the tablet T as the printing object is for medical use or dietary use, the ink used is preferably edible ink. As the edible ink, any one of synthetic pigment ink, natural pigment ink, dye ink, and pigment ink can be used.

[0157] Several embodiments of the present invention have been described above, but these embodiments are presented only as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the scope of the invention. These embodiments or their variations are included in the scope or spirit of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A tablet printing device, characterized in that: include: A feeding device for receiving a plurality of tablets and sequentially feeding the received tablets; a conveying device for conveying the tablets supplied from the supply device; The printing head is an inkjet type, and prints by ejecting ink droplets onto the tablet conveyed by the conveying device; A maintenance device for maintaining the printing head; as well as A control device controls the printing head and the maintenance device, Here, the control device causes the maintenance device to perform maintenance at a timing set based on the type of the tablet supplied from the supply device when printing is performed on the tablet.

2. The tablet printing device according to claim 1, characterized in that: The control device sets the timing so that the interval of maintenance by the maintenance device becomes longer for the tablet that is less likely to generate fine powder than for the tablet that is more likely to generate fine powder.

3. The tablet printing device according to claim 2, characterized in that: When any one of the coated tablets, the uncoated tablets, and the orally disintegrating tablets is supplied from the supply device, the control device sets the timing in such a manner that the interval for maintenance by the maintenance device is longer in the case of the uncoated tablets than in the case of the orally disintegrating tablets, and in such a manner that the interval for maintenance by the maintenance device is longer in the case of the coated tablets than in the case of the uncoated tablets.

4. The tablet printing device according to any one of claims 1 to 3, characterized in that: The control device sets the timing so that an interval of maintenance by the maintenance device becomes longer than when printing is performed on the tablets while the supply of the tablets from the supply device is stopped.

5. The tablet printing device according to claim 4, characterized in that: The conveying device comprises: A conveyor belt having a plurality of suction holes; and The suction part causes negative pressure to act on the suction hole, so that the suction hole sucks and holds the tablet, The control device sets the timing so that an interval of maintenance by the maintenance device becomes the longest during a period in which the supply of the tablets from the supply device is stopped and the suction unit is stopped.

6. The tablet printing device according to claim 4, characterized in that: The maintenance device comprises: an eraser for erasing the nozzle surface of the print head; and The liquid receiving portion receives the ink ejected from the printing head.

7. A tablet printing method, characterized in that: include: a supplying process, supplying tablets in sequence; A conveying step of conveying the supplied tablets in sequence; A printing step of printing the conveyed tablet by ejecting ink droplets from an inkjet printing head; as well as A maintenance process is performed on the print head at a predetermined timing. The maintenance process performed when the printing process is executed is performed at a timing set based on the type of the supplied tablets.

8. A tablet printing device, characterized in that: include: A feeding device for receiving a plurality of tablets and sequentially feeding the received tablets; a conveying device for conveying the tablets supplied from the supply device; The printing head is an inkjet type, and prints by ejecting ink droplets onto the tablet conveyed by the conveying device; A maintenance device for maintaining the printing head; as well as an eraser maintenance device for maintaining the eraser included in the maintenance device, The eraser includes an eraser for wiping the nozzle surface of the print head to absorb the liquid attached to the nozzle surface. The eraser maintenance device includes a suction nozzle for sucking the liquid held by the eraser.

9. The tablet printing device according to claim 8, characterized in that: The maintenance device further includes: a suction unit for sucking the nozzle surface; The tablet printing device further includes a common suction source that applies a suction force to the suction nozzle and the suction unit.

10. The tablet printing device according to claim 8 or 9, characterized in that: Also includes: a control device, wherein the control device controls the printing head and the maintenance device, The control device issues a warning that maintenance should be performed using the eraser maintenance device when the number of times the maintenance device performs maintenance on the print head reaches a predetermined number of times.

11. A tablet printing method, characterized in that: include: a supplying process, supplying tablets in sequence; A conveying step of conveying the supplied tablets in sequence; A printing step of printing the conveyed tablet by ejecting ink droplets from an inkjet printing head; A print head maintenance step, performing maintenance using a maintenance device, the maintenance device having: a suction unit for sucking the nozzle surface of the print head, and an eraser for wiping the nozzle surface of the print head; and The eraser maintenance process uses a suction nozzle to suck the liquid held by the eraser. Here, a suction source for applying suction force to the suction nozzle and a suction source for applying suction force to the suction portion are common.

12. The tablet printing method according to claim 11, characterized in that: The print head maintenance process and the eraser maintenance process are performed simultaneously.

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