Tablet printing apparatus

Abstract

The present invention provides a tablet printing apparatus that can prevent degradation of printing quality. The tablet printing apparatus (1) of the embodiment includes: a conveying device (20) for conveying tablets (T); a print head (51) of inkjet type for printing on the tablets (T) conveyed by the conveying device; a maintenance device (80) for maintaining the print head (51); and a control device (90) for controlling the print head (51) and the maintenance device (80), wherein the control device (90) changes the maintenance operation according to either or both of the type of tablet (T) to be conveyed or the type of ink.

Description

Technical Field

[0001] Embodiments of the present invention relate to a tablet printing apparatus. Background Technology

[0002] To print identification information such as text or markings on tablets, techniques using inkjet printheads are known. Tablet printing apparatuses using this technique utilize a conveyor to transport multiple tablets in a line, and eject ink (e.g., edible ink) from the nozzles of an inkjet printhead positioned above the conveyor toward the tablets passing below the printhead, thereby printing identification information onto the tablets on the conveyor.

[0003] In inkjet printheads, regular maintenance is required to maintain their ejection performance. Additionally, printhead maintenance is performed to restore ejection performance in case of ejection defects.

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

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

[0007] [The problem the invention aims to solve]

[0008] Uncoated tablets or orally disintegrating (OD) tablets, which are not coated on their surface, generate powder due to powder falling off or surface abrasion during transport. This powder sometimes adheres to the nozzle face of the printhead. If the nozzle becomes clogged due to powder adhering to the nozzle face, it will cause poor ejection. Poor ejection leads to reduced print quality.

[0009] Therefore, efficient printhead maintenance is required depending on the type of tablet.

[0010] The purpose of this invention is to provide a tablet printing apparatus that can prevent a reduction in printing quality.

[0011] [Technical means to solve the problem]

[0012] The tablet printing apparatus of the embodiment includes: a conveying device for conveying tablets; a print head, which is an inkjet printer for printing by spraying ink onto the tablets conveyed by the conveying device; a maintenance device for maintaining the print head; and a control device for controlling the print head and the maintenance device, wherein the control device changes the maintenance operation according to either or both of the type of tablets to be conveyed or the type of ink. Attached Figure Description

[0013] Figure 1 This is a front view showing the schematic structure of the tablet printing apparatus according to the first embodiment.

[0014] Figure 2 This is a plan view showing the schematic structure of the tablet printing apparatus according to the first embodiment.

[0015] Figure 3 This is a diagram illustrating an example of the schematic structure of the maintenance device according to the first embodiment.

[0016] Figure 4 This is a diagram illustrating an example of the schematic structure of the control device according to the first embodiment.

[0017] Figure 5 This is a flowchart illustrating the maintenance procedures of the first embodiment.

[0018] Figure 6 This is an operational status diagram of the maintenance device according to the first embodiment.

[0019] Figure 7 This diagram illustrates an outline of the maintenance procedures in the second embodiment.

[0020] [Explanation of Symbols]

[0021] 1: Tablet printing device

[0022] 10: Supply device

[0023] 11: Hopper

[0024] 12: Slide

[0025] 20: Transport device

[0026] 21: Conveyor belt

[0027] 21a: Suction port

[0028] 22: Drive pulley

[0029] 23: Driven pulley

[0030] 24, 84c: Motor

[0031] 25: Position Detector

[0032] 26: Suction Chamber

[0033] 30: Detection device

[0034] 31: Testing Department

[0035] 40: First camera device

[0036] 41: First Camera Department

[0037] 50: Printing apparatus

[0038] 51: Printing head

[0039] 51a: Nozzle

[0040] 52: Lifting mechanism

[0041] 60: Second camera device

[0042] 61: Second Camera Department

[0043] 70: Recycling device

[0044] 80: Maintenance device

[0045] 81: Liquid receiving part

[0046] 82: Suction section

[0047] 83: Eraser

[0048] 83a: First Eraser

[0049] 83b: Second eraser

[0050] 84: Mobile mechanism

[0051] 84a: Ball screw

[0052] 90: Control device

[0053] 90a: Input device

[0054] 90b: Output device

[0055] 91: Image Processing Department

[0056] 92: Storage Department

[0057] 93: Control Department

[0058] H1: Arrow / Direction of transport

[0059] S101, S102, S103, S104, S105, S106, S107, S108, S109, S110, S111, S112, S113, S114, S115, S116, S117: Steps

[0060] T: Tablets

[0061] X, Y, Z, θ: Direction Detailed Implementation

[0062] <First Implementation>

[0063] Reference Figures 1-6 The first embodiment will be described.

[0064] (Structure example of a tablet printing apparatus)

[0065] like Figure 1 and Figure 2 As shown, the tablet printing apparatus 1 of the first embodiment includes a feeding 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 recycling device 70, and a maintenance device 80 (see reference). Figure 2 ) and control device 90.

[0066] The supply device 10 includes a hopper 11 and a chute 12. Located at one end of the conveying device 20, the supply device 10 is configured to supply tablets T, which are the objects to be printed, to the conveying device 20. The hopper 11 holds multiple tablets T and sequentially supplies the held tablets T to the chute 12. The chute 12 arranges the tablets T supplied from the hopper 11 into a row and supplies them to the conveying device 20. The supply device 10 is electrically connected to a control device 90, and its operation is controlled by the control device 90.

[0067] The conveying device 20 includes: a conveyor belt 21, a drive pulley 22, multiple driven pulleys 23, a motor 24, a position detector 25, and a suction chamber 26. The conveyor belt 21 is a loop-shaped belt mounted on the drive pulley 22 and each driven pulley 23. The drive pulley 22 and each driven pulley 23 are rotatably mounted on the main body of the device (not shown), and the drive pulley 22 is connected to the motor 24. The motor 24 is electrically connected to a control device 90, and its drive is controlled by the control device 90. The position detector 25 is an encoder or similar device mounted on the motor 24. The position detector 25 is electrically connected to the control device 90 and sends detection signals to the control device 90. In the conveying device 20, the rotation of the drive pulley 22 caused by the motor 24 causes the conveyor belt 21 and each driven pulley 23 to rotate together, moving the tablets T on the conveyor belt 21 towards... Figure 1 The direction of rotation of arrow H1 in the diagram is the conveying direction, which is H1.

[0068] Multiple circular suction holes 21a are formed on the conveyor belt 21 (see reference). Figure 2 These suction holes 21a are through holes for adsorbing tablet T, arranged in two parallel rows along the conveying direction H1 to form two conveying paths. Each suction hole 21a passes through a suction chamber 26 (see reference). Figure 1 The suction path (not shown) connects to the suction chamber 26, thereby enabling suction force to be obtained through the suction chamber 26. The suction chamber 26 is connected to the pump (not shown) via a suction tube, and the pump depressurizes the suction chamber 26. The suction tube is connected to the approximate center of the side of the suction chamber 26 (the plane parallel to the conveying direction H1). In addition, the pump is electrically connected to the control device 90, and its drive is controlled by the control device 90. When the suction chamber 26 is depressurized, the tablets T placed on the suction holes 21a of the conveyor belt 21 are drawn in by the suction holes 21a and held on the conveyor belt 21.

[0069] The detection device 30 includes multiple detection units 31 (two in this embodiment). The detection units 31 are located downstream of the supply device 10 in the conveying direction H1 and are positioned above the conveyor belt 21. The detection units 31 detect the tablet T on the conveyor belt 21 in the X direction (refer to...) by laser beam projection / reception. Figure 2 The position on the device is detected. The detection unit 31 may use a displacement sensor or proximity sensor, for example. Alternatively, various laser sensors, such as reflective laser sensors, may be used as displacement sensors. The detection device 30 is electrically connected to the control device 90 and sends a detection signal to the control device 90.

[0070] The first imaging device 40 includes a plurality of first imaging units 41 (two in this embodiment). The first imaging units 41 are located downstream of the detection device 30 in the conveying direction H1 and are positioned above the conveyor belt 21. Based on the position information of the tablet T in the X direction detected by the detection device 30, the first imaging unit 41 captures an image (an image for tablet position detection) at an imaging moment when the tablet T reaches an imaging position directly below the first imaging unit 41, acquiring a first image including the upper surface of the tablet T, and sends the acquired first image to the control device 90. The first image is used to detect the position of the tablet T in the X, Y, and θ directions. Various cameras with imaging elements such as charge-coupled devices (CCDs) or complementary metal-oxide-semiconductor (CMOS) are used as the first imaging units 41. The first imaging device 40 is electrically connected to the control device 90, and its operation is controlled by the control device 90. Furthermore, imaging illumination is provided as needed.

[0071] Here, the position of tablet T in the X and Y directions is, for example, its position in the XY coordinate system relative to the center (reference position) of the imaging area of ​​the first camera unit 41. Additionally, the position in the θ direction represents, for example, the degree of rotation of tablet T relative to the centerline in the Y direction of the imaging area of ​​the first camera unit 41. The position in the θ direction is detected when tablet T has a directional shape, such as when it has dividing lines, or when it is shaped like an ellipse, oblong, or quadrilateral.

[0072] The printing apparatus 50 includes a print head 51 and a lifting mechanism 52. The print head 51 is located downstream of the first camera device 40 in the conveying direction H1 and is positioned above the conveyor belt 21. The print head 51 has a plurality of (e.g., hundreds to thousands) nozzles 51a (see reference). Figure 2 The nozzles 51a are arranged in a row (nozzle row) in a horizontal plane orthogonal to the conveying direction H1 (an example of intersection). Furthermore, in Figure 2 In the diagram, for simplicity, four nozzles 51a are shown. The printhead 51 ejects ink from each nozzle 51a individually through the action of a drive element. The printhead 51 can be a printhead using various inkjet printing methods, incorporating drive elements such as piezoelectric elements, heating elements, or magnetostrictive elements. The printhead 51 utilizes a lifting mechanism 52 (see reference 52). Figure 1 The printing head 51 can move up and down by approaching or moving away from the conveyor belt 21. The up and down movement of the printing head 51 is performed during maintenance of the printing head 51. Maintenance of the printing head 51 will be described later. The printing unit 50 is electrically connected to the control unit 90, and its drive is controlled by the control unit 90.

[0073] The second imaging device 60 includes a plurality of second imaging units 61 (two in this embodiment). The second imaging units 61 are located downstream of the printing device 50 in the conveying direction H1 and are positioned above the conveyor belt 21. Based on the position information of the tablet T in the X direction detected by the first imaging unit 41 and the detection unit 31, the second imaging unit 61 captures an image at a timing when the tablet T reaches the imaging position directly below the second imaging unit 61, acquiring a second image including the upper surface of the tablet T, and sends the acquired second image to the control device 90. The second image is used to inspect the printed pattern printed on the tablet T. Similar to the first imaging unit 41, the second imaging unit 61 may be a camera with an imaging element such as a CCD or CMOS. The second imaging device 60 is electrically connected to the control device 90, and its operation is controlled by the control device 90. Furthermore, imaging illumination is provided as needed.

[0074] The recovery device 70 is located downstream of the second camera device 60 in the conveying direction H1, and is situated at the downstream end of the conveying device 20 in the conveying direction H1. The conveying device 20 releases its grip on the tablet T when the tablet T on the conveyor belt 21 reaches a predetermined position, such as the downstream end of the conveying direction H1 in the conveying device 20. The recovery device 70 is configured to separate the tablet T, which falls after the release of the grip from the conveying device 20, into defective and good products for recovery. For example, by blowing gas onto the falling tablet T, changing the falling direction of the tablet T according to defective and good products, or by using a plate or other components to change the falling path, the falling tablet T can be separated into defective and good products for recovery. For example, defective products are those with printing defects, and good products are those with printing defects. The recovery device 70 is electrically connected to the control device 90, and its operation is controlled by the control device 90.

[0075] like Figure 2 and Figure 3 As shown, the maintenance device 80 includes a liquid receiving part 81, a suction part 82, a wiper 83, and a moving mechanism 84. The maintenance device 80 is arranged in the same direction as the nozzles 51a of the print head 51 when viewed from above. Figure 2 They are arranged side by side in the Y direction. Furthermore, in... Figure 2 For the sake of simplicity, the moving mechanism 84 has been omitted. Details of the maintenance device 80 will be described later.

[0076] 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 is electrically connected to the control device 90, and its drive is controlled by the control device 90.

[0077] The control device 90 controls various parts of the tablet printing apparatus 1 based on various information and programs, such as the supply device 10 or conveying device 20, the detection device 30, the first camera device 40, the printing device 50, the second camera device 60, the recycling device 70, and the maintenance device 80. Furthermore, the control device 90 receives detection information (e.g., detection signals) sent from the position detector 25 or the detection device 30, and image information sent from the first camera unit 41 or the second camera unit 61. The control device 90 is implemented, for example, through electronic circuits such as integrated circuits or computers.

[0078] Next, refer to Figure 4 The structure of the control device 90 will be described.

[0079] like Figure 4As shown, the control device 90 includes 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, for example, through a switch, touchscreen, keyboard, mouse, etc. The output device 90b is implemented, for example, through a display, lamp, instrument, etc.

[0080] 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, gaps, or dirt, and further obtains the position of the tablet T in the X, Y, and θ directions. Additionally, 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 (e.g., text or markings) printed on the tablet T. The image processing unit 91 sends the acquired information on whether the tablet T has cracks, gaps, or dirt, the acquired position information of each tablet T in the X, Y, and θ directions, and the printing position, shape, and size information of the printed pattern on each tablet T to the control unit 93.

[0081] The storage unit 92 stores processing information or various programs. For example, it can be implemented using semiconductor memory elements such as Random Access Memory (RAM) or Flash Memory, or storage devices such as hard disks or optical discs. The storage unit 92 stores data such as the type of tablet to be printed, data on the ink used in printing, printing-related data, and the movement speed data of the conveyor belt 21. The printing data includes information about printed patterns such as text or markings.

[0082] The control unit 93, such as a central processing unit (CPU) or microprocessor (MPU), controls various components. For example, based on various information or programs stored in the storage unit 92, the control unit 93 controls the supply device 10 or conveying device 20, the detection device 30, the first camera device 40, the printing device 50, the second camera device 60, the recycling device 70, the maintenance device 80, the image processing unit 91, and the storage unit 92. Furthermore, the control unit 93 receives detection signals from the detection device 30 or the position detector 25. Moreover, the control unit 93 is implemented, for example, through one or both hardware and software.

[0083] For example, based on the detection information sent by the self-detection device 30, i.e., the timing of detecting tablet T on the conveyor belt 21, the control unit 93 obtains the position of tablet T in the X direction on the conveyor belt 21. Based on the position information representing the position of tablet T in the X direction, it sets the camera timing of the first camera device 40, the printing start timing of the printing head 51 of the printing device 50, and the camera timing of the second camera device 60, generates timing information representing these timings, and saves it in the storage unit 92. The printing start timing refers to the timing when printing begins on 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 amount of movement (rotation) or speed of the conveyor belt 21 based on the detection information sent by the self-position detector 25.

[0084] Furthermore, the control unit 93 determines whether to print on the tablet T, based on information sent from the image processing unit 91 regarding whether the tablet T has cracks, nicks, or dirt. The control unit 93 also sets printing conditions for tablets T that are set as printable. At this time, the control unit 93 sets printing conditions for tablets T based on the position information of the tablet T in the X, Y, and θ directions sent from the image processing unit 91, based on the position information of the tablet T in those directions. For example, the control unit 93 determines the range of nozzles 51a used in printing on the target tablet T in the print head 51, i.e., the nozzle range used, based on the position information of the tablet T in the Y direction or printing data, and sets printing conditions including the nozzle range used or the printing start time. Furthermore, when the tablet T has a directional shape, the control unit 93 sets printing conditions corresponding to the position of the tablet T in the θ direction based on the position information of the tablet T in that direction. As an example, the control unit 93 registers 180 printing patterns obtained by rotating the orientation of the printing pattern by one degree each time within the range of 0 to 179 degrees into the storage unit 92, and selects the 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.

[0085] Furthermore, 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, the control unit 93 determines whether the printed pattern is printed on the tablet T in a specified position with a specified shape and size, that is, whether the printed pattern is printed normally on the tablet T (printing status check). For example, when determining the shape and size of the printed pattern, the control unit 93 registers the printed pattern for inspection in the storage unit 92 and compares the printed pattern for inspection with the actual printed pattern on the tablet T (the printed pattern printed on the tablet T).

[0086] Furthermore, the control unit 93 is suitable for storing various information (e.g., information on whether tablet T has cracks or gaps, dirt, or location information, timing information, printing conditions, printing quality information, etc.) in the storage unit 92. However, when the target tablet T is collected by the recycling device 70, for example, after it falls off at the downstream end of the conveying direction H1 in the self-conveying device 20 and a predetermined time (e.g., several seconds) has elapsed, the various information is deleted from the storage unit 92. However, if this information is needed in subsequent processes, the various information of each tablet T may not be deleted and may be retained, or stored in a storage medium outside the device. When the various information of each tablet T is stored in advance, the information can be linked to the manufacturing date or batch number, etc., so that for the printed tablet T, it is possible to trace back to the case where defective products were produced after leaving the factory to investigate the cause.

[0087] (Example of the structure of a maintenance device)

[0088] Next, refer to Figure 3 The structure of the maintenance device 80 is described. Figure 3 This is a view of the printhead 51 and maintenance device 80 from the upstream side of the conveying direction H1. As described above, the maintenance device 80 includes a liquid receiving part 81, a suction part 82, an eraser 83, and a moving mechanism 84. When not in use, they are positioned in the order of eraser 83, suction part 82, and liquid receiving part 81 from the printhead 51 side, and are configured to be movable integrally by the moving mechanism 84.

[0089] The liquid receiving portion 81 is, for example, formed in a box shape with an open top. During maintenance of the printhead 51, the liquid receiving portion 81 receives ink ejected from each nozzle 51a of the opposing printheads 51. The length of the liquid receiving portion 81 in the direction orthogonal to the transport direction H1 is set to be at least longer than the nozzle array formed by the nozzles 51a. In the first embodiment, the length of the liquid receiving portion 81 in the direction orthogonal to the transport direction H1 is longer than the length of two side-by-side printheads 51 (longer than the two printheads).

[0090] The suction unit 82 is a vacuum eraser with a slit-shaped suction port extending along the conveying direction H1 at its upper part. The length of the slit-shaped suction port is approximately 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 scanning manner near the nozzle surface of the print head 51, thereby suctioning and removing ink adhering to the nozzle surface.

[0091] The eraser 83 slides while in contact with the nozzle surface of the print head 51, thereby wiping away and removing powder or ink adhering to the nozzle surface. The eraser 83 includes a first eraser 83a and a second eraser 83b.

[0092] The first wiper 83a has an upper portion made of a absorbent fibrous material, such as non-woven fabric. The first wiper 83a is impregnated with a wiping liquid (e.g., an aqueous solution containing ethanol). That is, the first wiper 83a is a wet wiper. Furthermore, the supply of the wiping liquid to the first wiper 83a can be performed by an operator or automatically. By being supplied with the wiping liquid, the first wiper 83a becomes impregnated with the wiping liquid.

[0093] Like the first wiper 83a, the second wiper 83b has a liquid-absorbing fibrous material, such as non-woven fabric, on its upper part. The second wiper 83b is a dry wiper (not supplied with wiping liquid).

[0094] The moving mechanism 84 includes a ball screw 84a, a slider 84b, and a motor 84c. The liquid receiving part 81, the suction part 82, and the wiper 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 via the motor 84c. Here, the maintenance position refers to the position of the maintenance device 80 during maintenance of the print head 51, specifically the position between the conveyor belt 21 and the print head 51. The standby position refers to the position of the maintenance device 80 when no maintenance is performed, specifically a position offset from above the conveyor belt 21. Figure 1 (The position on the inside of the paper).

[0095] (Printing process)

[0096] Next, refer to Figure 1 and Figure 2 The printing process performed by the tablet printing apparatus 1 will be described. The printing process also includes an inspection process. In addition, various information such as data required for printing are pre-stored in the storage unit 92.

[0097] When the tablet printing apparatus 1 begins printing, the motor 24 is driven, and the conveyor belt 21 rotates in the conveying direction H1, accompanied by the rotation of the drive pulley 22 and driven pulley 23 caused by the motor 24. While the conveyor belt 21 is rotating in the conveying direction H1, tablets T are sequentially fed from the hopper 11 to the chute 12, and are arranged in a row and randomly, rather than at fixed intervals, fed onto the conveyor belt 21. The tablets T supplied to the conveyor belt 21 are arranged in two rows and conveyed at a predetermined speed.

[0098] The tablet T on the conveyor belt 21 is detected by the detection device 30. Specifically, the detection device 31 detects when the tablet T on the conveyor belt 21 reaches a detection position (e.g., a laser irradiation position) directly below the detection unit 31 of the detection device 30. Based on the timing of the detection of the tablet T, the control unit 93 identifies the position of the tablet T in the X direction on the conveyor belt 21. Then, the control unit 93 generates position information indicating the position of the tablet T in the X direction and stores it in the storage unit 92.

[0099] Next, the first camera device 40 captures an image of the tablet T on the conveyor belt 21. Specifically, the first camera device 40 captures an image when the tablet T on the conveyor belt 21 reaches a camera position directly below it, and the first image obtained by the first camera device 40 is sent to the control device 90. Based on the first image, the image processing unit 91 generates information about whether the tablet T has cracks, nicks, or dirt, as well as the position information of the tablet T in the X, Y, and θ directions, and stores this information in the storage unit 92. Based on the information about whether the tablet T has cracks, nicks, or dirt, it is determined whether printing can be performed on the target tablet T. Furthermore, based on the position information of the tablet T in the X, Y, and θ directions, or information such as the printing pattern, printing conditions are set in the storage unit 92. These printing conditions include the nozzle range used for the tablet T that is set to be printable (printable tablet T) and the timing of printing start. Furthermore, based on the printing start time (the time when printing begins on tablet T), the ink ejection time (the time when ink is ejected from tablet T) is determined.

[0100] Based on the aforementioned printing conditions, printing is performed by the printing apparatus 50. Specifically, the control unit 93 controls the printing head 51 of the printing apparatus 50 to print a predetermined pattern onto the printable tablet T on the conveyor belt 21. In detail, printing begins when the printable tablet T on the conveyor belt 21, having passed below the first camera device 40, reaches the printing position directly below the printing head 51, based on the aforementioned printing conditions. In the printing head 51, ink is appropriately ejected from each nozzle 51a, printing a pattern (e.g., numbers, letters, katakana, symbols, graphics) onto the upper surface of the tablet T, i.e., the printing surface. The ink applied to the tablet T dries during the conveying process. Alternatively, a drying section (not shown) that utilizes gas or heat for drying may be provided, through which the ink is dried.

[0101] Subsequently, the second camera device 60 captures an image of the printed tablet T on the conveyor belt 21. Specifically, the second camera device 60 captures an image when the printed tablet T on the conveyor belt 21 reaches a camera position directly below the second camera device 60, and the second image obtained by capturing the image using the second camera device 60 is sent to the control device 90.

[0102] 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 on the tablet T, namely the printing position, shape, and size of the printed pattern. The image processing unit 91 analyzes the second image sent from the second camera device 60, generates inspection information indicating the printing position, shape, and size of the printed pattern on the tablet T, and saves it in the storage unit 92.

[0103] Based on the inspection information, the control unit 93 performs a printing status inspection. Specifically, based on the inspection information stored in the storage unit 92 regarding the printing position, shape, and size, the control unit 93 determines whether the printing pattern is correctly printed on the tablet T, generates printing quality information indicating whether the printing on the tablet T is good, and stores it in the storage unit 92. For example, in the printing status inspection, the printing pattern used in printing is stored in the storage unit 92 as an inspection printing pattern. Good product information related to the specified printing position, shape, and size of the inspection printing pattern is compared with the inspection information stored in the storage unit 92 related to the printing position, shape, and size of the actually printed printing pattern to determine whether the printing pattern is correctly printed on the tablet T (qualified or unqualified).

[0104] Finally, the tablets T on the conveyor belt 21 are collected by the recycling device 70. Specifically, after inspection, when the tablets T are located at the downstream end of the conveyor belt 21 as it moves, they are released from their position on the conveyor belt 21 and fall off the conveyor belt 21 to be collected by the recycling device 70. At this time, tablets T that are qualified fall directly and are collected by the recycling device 70 as good products, but tablets T that are unqualified or unprinted are separated from the good products by air blowing midway down from the conveyor belt 21 and are collected by the recycling device 70 as defective products.

[0105] (Maintenance Procedure)

[0106] During the printing process, the print head 51 is maintained periodically (e.g., every 10 to 20 minutes). Maintenance methods include cleaning or wiping, and pre-ejection. Cleaning refers to the action of pressing ink through the print head 51 with the liquid receiving section 81 facing it, thereby ejecting ink from the print head 51 toward the liquid receiving section 81. By performing the cleaning action, air bubbles or dried, solidified ink within the nozzle can be removed, thus preventing poor ejection. Wiping refers to the action of suctioning the nozzle surface of the print head 51 using the suction section 82 or wiping it using the wiper 83. By wiping, powder or ink adhering to the nozzle surface can be removed, thereby preventing poor ejection. Pre-ejection refers to the action of driving the inkjet drive element with the liquid receiving section 81 facing the print head 51 to eject a small amount of ink (pre-ejection action).

[0107] However, as mentioned above, powder is sometimes generated during printing on uncoated sheets, and this powder adheres to the nozzle surface. Typically, in the nozzle of an inkjet printhead, the ink filling the nozzle is shaped to form a concave meniscus at the nozzle exit point by means of a water level difference in the ink container connected to the printhead. Therefore, during cleaning, a portion of the ink extruded from the nozzle, along with the powder adhering to the nozzle exit point and surrounding area, is drawn into the nozzle to re-form the meniscus. This can cause nozzle clogging and sometimes result in poor ejection.

[0108] Therefore, when the tablet T to be printed is an uncoated tablet, during the maintenance of the print head 51, wiping is performed before cleaning (before the ejection operation) to remove powder adhering to the nozzle surface. On the other hand, when the tablet T to be printed is a coated tablet (sugar-coated tablet, film-coated tablet, etc.) that produces little or no powder, wiping is not required before cleaning. Details of this maintenance process will be explained below.

[0109] The maintenance procedure for printhead 51 is shown below. Figure 5 . Figure 5 The process shown is performed by each part under the control of the control device 90. Furthermore, the type of tablet T to be printed is pre-input by the operator via the input device 90a at the start of printing operation and stored in the storage unit 92. During maintenance procedures, the supply of tablet T by the supply device 10 is temporarily stopped.

[0110] First, the case where the tablet T to be printed is a coated tablet will be explained. When it is time to maintain the print head 51, 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 will not come into contact with the suction unit 82 and the wiper 83 even if the suction unit 82 and the wiper 83 are moved as described later.

[0111] Next, the moving mechanism 84 is controlled, and the liquid receiving part 81 is positioned facing the nozzle surface of the printing head 51. Then, the lifting mechanism 52 is controlled, such as... Figure 6 As shown, the print head 51 is lowered to a height at which the nozzle surface of the print head 51 does not come into contact with the suction part 82 but with the eraser 83 during the erasure process (step S102).

[0112] If the control device 90 determines that the tablet T to be printed is a coated tablet based on the information of the type of tablet T that was previously input by the operator via the input device 90a and stored in the storage unit 92 (step S103: No), then the ink in the print head 51 is pressed to perform a cleaning operation (step S104).

[0113] Next, the moving mechanism 84 is controlled to move the suction unit 82 and the wiper 83 toward each other. Figure 6 The print head 51 is moved to the left. As a result, the print head 51 is sequentially subjected to vacuum erasure using the suction unit 82 (step S105), wet erasure using the first eraser 83a (step S106), and dry erasure using the second eraser 83b (step S107).

[0114] After erasing is completed, the lifting mechanism 52 is controlled to raise the print head 51 (step S108). When the print head 51 rises, the moving mechanism 84 is controlled to position the liquid receiving part 81 facing the nozzle surface of the print head 51 (step S109). With the liquid receiving part 81 facing the nozzle surface of the print head 51, the ink ejection drive element of the print head 51 is driven to perform virtual ink ejection (step S110).

[0115] After the virtual ejection is completed, the moving mechanism 84 is controlled to move the maintenance device 80 (suction unit 82 and wiper 83) to the standby position (step S111), and the lifting mechanism 52 is controlled to lower the print head 51 to the height position for printing operation (step S112). After the print head 51 is lowered, the maintenance process ends. After the maintenance process is completed, the feeding of tablet T using the supply device 10 is restarted, and the printing operation begins.

[0116] Next, the case where the tablet T to be printed is an uncoated tablet will be described. When it is time to maintain the print head 51, similar to the case of coated tablets, the print head 51 rises (step S101), the liquid receiving part 81 is positioned facing the nozzle surface of the print head 51, and then the print head 51 falls (step S102). Subsequently, in step S103, if the control device 90 determines that the tablet T to be printed is an uncoated tablet based on the type information of the tablet T to be printed that was previously input by the operator via the input device 90a and stored in the storage unit 92 (step S103: Yes), then the process proceeds to step S113 to perform wiping.

[0117] That is, the moving mechanism 84 is controlled to make the suction part 82 and the wiper 83 move towards Figure 6 The printhead 51 moves to the left. As a result, the printhead 51 is sequentially subjected to vacuum wiping using the suction unit 82 (step S113), wet wiping using the first wiper 83a (step S114), and dry wiping using the second wiper 83b (step S115). Through these wiping processes, powder adhering to the nozzle surface of the printhead 51 can be removed.

[0118] After erasing is complete, the lifting mechanism 52 is controlled to raise the print head 51 (step S116). Once the print head 51 is raised, the moving mechanism 84 is controlled, positioning the liquid receiving part 81 facing the nozzle surface of the print head 51. Then, the lifting mechanism 52 is controlled, such as... Figure 6 As shown, the print head 51 is lowered to the height at which the eraser 83 contacts the nozzle surface of the print head 51 during the erasure process (step S117).

[0119] After the printing head 51 descends, the steps following step S104 are performed in the same manner as when the tablet T is a coated tablet.

[0120] As explained above, according to the first embodiment, the tablet printing apparatus 1 includes: a conveying device 20 for conveying tablets T; a print head 51, which is an inkjet printer for printing on the tablets T conveyed by the conveying device 20; a maintenance device 80 for maintaining the print head 51; and a control device 90 for controlling the print head 51 and the maintenance device 80, wherein the control device 90 changes the maintenance operation according to the type of tablets T to be conveyed. This allows for efficient maintenance. Therefore, it prevents situations where poor inkjet printing leads to reduced print quality.

[0121] Furthermore, in the first embodiment, when the printing object is a sheet without coating, wiping is performed before cleaning (before the ejection operation). Wiping removes powder adhering to the nozzle surface. Therefore, during cleaning, it prevents powder from being drawn into the nozzle along with some of the ink extruded from the nozzle as it is re-forming the meniscus. This prevents poor ejection and reduced print quality.

[0122] Furthermore, in the first embodiment, vacuum wiping is performed using the suction unit 82 before wet wiping using the first wiper 83a. Due to printing operation, powder sometimes adheres to the nozzle surface, and also adheres to the ink adhering to the nozzle surface, thus mixing in powder. By performing vacuum wiping before wet wiping, the powder mixed in with the ink can be removed simultaneously. Ink that was not completely removed by vacuum wiping can be removed by wet wiping. Then, after wet wiping using the first wiper 83a, dry wiping is performed using the second wiper 83b. The wiping liquid adhering to the nozzle surface due to wet wiping can be removed by dry wiping. This wiping method allows for efficient cleaning of the printhead 51.

[0123] On the other hand, when printing on coated sheets, little or no powder adheres to the nozzle surface, so wiping is not necessary before cleaning. Therefore, by maintaining the printhead, poor ejection can be prevented while reducing maintenance time.

[0124] <Second Implementation>

[0125] Next, the second embodiment will be described. In the second embodiment, only the differences from the first embodiment will be described; the similarities will be omitted.

[0126] Inks used for printing on tablets sometimes contain fixing materials, depending on their composition or the physical properties of the tablets to be printed.

[0127] Fixing materials, for example, can be substances classified as pastes or adhesives, thickeners, and stabilizers. Specifically, these include acetylated adipic acid cross-linked starch, acetylated oxidized starch, acetylated phosphoric acid cross-linked starch, acetate starch, oxidized starch, hydroxypropyl starch, phosphoric acid cross-linked starch, phosphoric acid oxidized starch, and phosphoric acid monoesterified phosphoric acid cross-linked starch. Other materials include okra extract, seaweed cellulose, brown algae extract, gluten protein, gluten protein breakdown products, konjac extract, sweet potato cellulose, coconut jelly, mannan, and rennet casein. In addition, there are Aureobasidium culture medium, Agrobacterium succinoglycan, linseed gum, gum arabic, arabinogalactan, alginic acid, welan gum, elemi resin, ceresin, cinnamon gum, ghatti gum, condensing polysaccharides, carrageenan (processed Eucheuma algae, refined carrageenan, Eucheuma algae powder), karaya gum, carob bean gum, xanthan gum, chitin, chitosan, guar gum, guar gum hydrolysate, guaiac resin, gutta-percha, gutta-percha, glucosamine, yeast cell wall, psyllium seed gum, Artemisia argyi seed gum, shellac (white shellac, refined shellac), gellan gum. gum, jelutong gum, sorva gum, sorvinha gum, tamarind seed gum, tara gum, chicle, chilte, tunu gum, low molecular weight rubber, dextran, tragacanth gum, okra rhizome, natto gum, Niger gutta, paraffin wax, microfibrillated cellulose, red algae gum, algae extract, pullulan, powdered rice husk, pectin, Venezuelan chicle, Macropomum gum, mastic, Massaranduba balata gum, myrrh, peach gum, Rhamsan gum, Leche de Vacca), fructan, rosidin, glycosides, etc.

[0128] Inks containing fixers can prevent ink from peeling or thinning due to friction during printing. However, if fixers are included, the ink viscosity increases, or when it dries and solidifies, its adhesion to the nozzle surface becomes stronger, sometimes making it impossible to completely remove the ink even with wiping.

[0129] Therefore, in the second embodiment, the amount of wiping liquid supplied to the first eraser 83a (wet eraser) and the number of virtual ejection points are varied depending on whether the ink supplied to the print head 51 contains a fixer (the type of ink). A summary of the description of the second embodiment is shown below. Figure 7 .

[0130] Information about the inks used in printing is pre-input by the operator to the control device 90 via input device 90a. Before starting printing operation of the tablet printing unit 1 or before starting a maintenance process, wiping fluid is supplied to the first wiper 83a. At this time, if the ink contains a fixer, the amount of wiping fluid supplied is increased compared to the case where it does not contain a fixer. Additionally, during the maintenance process, virtual ejection (…) Figure 5 In step S110), when the ink contains a fixer, the number of virtual sprays (dots) is increased compared to the case where the ink does not contain a fixer.

[0131] Alternatively, the support member supporting the first wiper 83a can be shaped like a box with an open top, and the wiping liquid can be stored therein. In this case, by immersing a portion of the lower side of the first wiper 83a (the side opposite to the side that abuts the nozzle surface) in the wiping liquid stored in the container, the first wiper 83a can be kept wet for a longer period of time. Furthermore, in addition to increasing the amount of wiping liquid supplied to the first wiper 83a, the amount of wiping liquid contained in the first wiper 83a can also be increased by increasing the capacity of the container (the support member of the first wiper 83a). Additionally, the amount of wiping liquid contained in the first wiper 83a can be changed by altering the volume of the portion of the first wiper 83a immersed in the wiping liquid.

[0132] As explained above, the second embodiment achieves the same effects as the first embodiment. Furthermore, in the second embodiment, the amount of wiping liquid supplied to the first wiper 83a is varied depending on whether the ink contains a fixer. More specifically, if the ink contains a fixer, the amount of wiping liquid supplied to the first wiper 83a is increased. Therefore, wiping can be performed using the first wiper 83a containing a large amount of wiping liquid. Thus, even if the ink contains a fixer, the ink will dissolve, making it easier to remove ink adhering to the nozzle surface.

[0133] Furthermore, during wet erasure, the erasure liquid seeps out of the first eraser 83a due to the pressure when the nozzle surface comes into contact with it. Some of the seeping erasure liquid sometimes enters the nozzle. If the erasure liquid enters the nozzle, the ink inside the nozzle becomes thinner. If the first eraser 83a contains a large amount of erasure liquid, the amount of seeping erasure liquid also increases, and the amount of erasure liquid entering the nozzle sometimes increases as well. Therefore, when the first eraser 83a performs erasure with a large amount of erasure liquid, the number of sprays (dots) is increased during virtual spraying. By performing virtual spraying, the erasure liquid that has entered the nozzle can be discharged. This prevents the ink from thinning and the printable identification information from becoming less legible when the printing operation resumes subsequently.

[0134] <Other Implementation Methods>

[0135] In the foregoing description, two printheads 51 are provided, but one or more may also be used. Furthermore, a maintenance device 80 may be provided for each printhead 51, or multiple printheads 51 may share a single maintenance device 80.

[0136] In addition, the liquid receiving part 81, the suction part 82, and the wiper 83 are shown as moving as a single unit, but this is not the only example. They can also be configured to move independently.

[0137] Furthermore, an example is shown where the eraser 83, suction unit 82, and liquid receiving unit 81 move toward the print head 51 via the moving mechanism 84, but this is not a limitation. For example, it can be configured to move the print head 51, or it can be configured to move both the print head 51 and the maintenance device. That is, it is sufficient as long as the print head 51 and the maintenance device 80 move relative to each other.

[0138] Furthermore, when the wiping fluid is automatically supplied to the first eraser 83a, it is sufficient to simply provide a wiping fluid supply unit on the first eraser 83a. If a wiping fluid supply unit is provided, the amount of wiping fluid supplied to the first eraser 83a can be varied by controlling the wiping fluid supply unit, whether the ink contains a fixer or not.

[0139] Alternatively, the system can be configured such that an erasing fluid supply unit (not shown) is provided separately from the first eraser 83a, and erasing fluid is supplied to the first eraser 83a periodically. The amount of erasing fluid supplied periodically can be varied depending on the type of ink. For example, when using ink containing a fixer, the amount of erasing fluid supplied to the first eraser 83a can be increased. Alternatively, the frequency of erasing fluid supply to the first eraser 83a can be increased.

[0140] Alternatively, a wetness detection sensor can be provided to detect the amount of cleaning fluid contained in the first wiper 83a (the wetness state of the first wiper 83a). The wetness detection sensor sends the detected value to the control device 90. The control device 90 can determine the wetness state of the first wiper 83a based on the detected value sent by the wetness detection sensor. The control device 90 can control the device based on the determination result to change the number of virtual sprays. Alternatively, the relationship between the elapsed time after the cleaning fluid is supplied to the first wiper 83a or the number of wipes and the wetness state can be determined in advance through experiments, etc. Based on this, the wetness state of the first wiper 83a at the timing of wiping can be determined, and control can be performed to change the number of virtual sprays.

[0141] Furthermore, when the tablet T to be printed is an uncoated tablet, an example is given of removing powder by wiping it off before cleaning, but the method of powder removal is not limited to this. For example, cleaning fluid may be supplied directly to the nozzle surface of the print head 51. That is, any method that can remove powder adhering to the nozzle surface is acceptable.

[0142] In addition, the second wiper 83b only needs to be able to remove the wiping liquid (cleaning liquid) adhering to the nozzle surface, and for example, it can be set as a scraper.

[0143] Furthermore, while an example is given of the ink information used in printing being input by an operator to the control device 90 via input device 90a, this is not a limitation. For example, the tablet printing apparatus 1 may include a radio frequency (RF) tag reader, which obtains ink information by reading the RF tag attached to the ink container when the ink container (bottle or box) is mounted on the tablet printing apparatus 1. Alternatively, a barcode or QR code may be mounted on the ink container, and the ink information may be input to the tablet printing apparatus 1 by reading the barcode or QR code.

[0144] Furthermore, the amount of erasing liquid supplied to the first eraser 83a can be adjusted according to the composition of the ink. For example, it can be adjusted according to the type or content of the fixer. Additionally, the number of virtual ejections can be varied according to the amount of erasing liquid supplied to the first eraser 83a. That is, it can be configured such that the number of virtual ejections increases with the increase of the amount of erasing liquid.

[0145] Furthermore, an example was given of varying the number of ejections during virtual ejection based on whether the ink contains fixer, but this is not the only possibility. For instance, the ejection volume of each ejection in the virtual ejection could also be varied. Alternatively, both the number of ejections and the ejection volume could be varied.

[0146] Furthermore, while the example illustrates the periodic performance of the maintenance procedure during printing operations, it is not limited to this; it can also be performed when there is poor ejection from nozzle 51a or when printing defects are detected based on the second image. Performing the maintenance procedure restores the ejection performance of the printhead 51.

[0147] Furthermore, while the wiping speed using the first eraser 83a and the second eraser 83b is not specifically described in the maintenance process, it can be configured such that the moving speed (the speed at which the eraser 83 slides on the nozzle surface of the print head 51) of the first eraser 83a and the second eraser 83b is controlled by controlling the moving mechanism 84. For example, it can be configured such that the control unit 93 pre-counts the number of times the print head 51 is wiped, and when the number exceeds a predetermined number, the moving speed of the moving mechanism 84 is reduced to decrease the moving speed of the first eraser 83a and the second eraser 83b. Alternatively, it can be configured such that the control unit 93 measures the time since the tablet printing apparatus 1 begins operation, and determines that the number of wipes performed using the eraser 83 has exceeded the predetermined number if a predetermined time has elapsed, thereby reducing the moving speed of the moving mechanism 84 to decrease the moving speed of the first eraser 83a and the second eraser 83b. The nozzle surface of the print head 51 may also experience ink adhesion and accumulation as the operating time increases. However, by reducing the moving speed of the moving mechanism 84 by the control unit 93, and especially by ensuring that the wiping fluid in the first eraser 83a is adequately supplied to the nozzle surface of the print head 51, the ink adhering to the nozzle surface can be appropriately removed. Control can be implemented not only when wiping exceeds a predetermined number of times or after a predetermined time, but also by gradually reducing the speed from the start of operation of the tablet printing apparatus 1. Furthermore, the wiping speed of only one of the first eraser 83a and the second eraser 83b can be reduced, for example, by reducing the moving speed of only the first eraser 83a while adequately supplying wiping fluid to the nozzle surface of the print head 51, thereby removing the adhering ink. In this case, it is preferable that the first eraser 83a and the second eraser 83b be configured to move independently. For example, it can 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 different moving mechanism (in the same direction as the moving mechanism 84).

[0148] Furthermore, while the second eraser 83b is a dry eraser, it gradually becomes wetted as the operating time increases due to the absorption of ink adhering to the nozzle surface of the print head 51 or the erasing liquid supplied from the first eraser 83a. Therefore, a drying unit (not shown) for drying the second eraser 83b can be provided. The control unit 93, for example, dries the second eraser 83b via the drying unit at points when the number of erasures performed using the eraser 83 exceeds a predetermined number, or at points when the operating time of the tablet printing apparatus 1 has elapsed for a predetermined period. The drying unit preferably dries the second eraser 83b by spraying drying gas away from the nozzle surface of the print head 51. This is to prevent the nozzle surface of the print head 51 from drying due to the drying gas, causing the ink on the nozzle 51a to solidify and resulting in poor printing. The drying unit can, for example, be configured to supply drying gas from a drying section that dries the ink coated on the tablet T via piping (not shown). The drying gas supplied from the drying unit to the second wiper 83b can be configured to gradually increase its flow rate. That is, it can be configured such that whenever the number of wipes performed by the second wiper 83b increases, the supply of drying gas supplied by the drying unit is increased, thereby making the second wiper 83b dry more reliably.

[0149] Here, the tablet T may include tablets used for pharmaceutical, dietary, cleaning, industrial, or aromatic purposes. Furthermore, the tablet T may be a bare tablet, sugar-coated tablet, film-coated tablet, enteric-coated tablet, gelatin-coated tablet, multilayer tablet, cored tablet, etc., and various capsules such as hard capsules or soft capsules may also be included in the tablet T. Furthermore, the tablet T may have various shapes such as disc-shaped, lens-shaped, triangular, or elliptical. Additionally, when the tablet T to be printed is for pharmaceutical or dietary use, edible ink is suitable as the ink used. As the edible ink, any one of synthetic pigment ink, natural pigment ink, dye ink, or pigment ink can be used.

[0150] The foregoing has described several embodiments of the present invention, but these embodiments are merely 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, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments or their variations are included within the scope or spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A tablet printing apparatus, comprising: Transport device to transport tablets; The printhead is an inkjet printer that sprays ink onto the tablets conveyed by the conveying device for printing. A maintenance device is used to maintain the printhead; as well as The control device controls the print head and the maintenance device. The maintenance device includes a wiper that wipes the nozzle surface of the print head. When the tablets to be transported are uncoated tablets, the control device begins the maintenance operation in the order of ink being ejected from the printhead after the wiping is performed. When the tablets to be transported are coated tablets, the control device begins the maintenance operation in the order of wiping after ink is ejected from the printhead.

2. The tablet printing apparatus according to claim 1, wherein, The eraser has: The first wiper is a wet wiper supplied with wiping fluid; as well as The second wiper is a dry wiper. The control device is controlled to erase in the order of the first eraser and the second eraser.

3. The tablet printing apparatus according to claim 2, wherein, The maintenance device also includes a suction unit, which further suctions the nozzle surface. The control device controls the operation in the following sequence: suction using the suction unit, wiping using the first wiper, and wiping using the second wiper.

4. The tablet printing apparatus according to claim 2 or 3, characterized in that, When the number of erasures performed using the first eraser and the second eraser exceeds a predetermined number, the control device reduces the erasure speed of at least one of the first eraser and the second eraser.

5. The tablet printing apparatus according to claim 2 or 3, characterized in that, It also includes a drying unit that dries the second wiper. When the number of times the second eraser is used exceeds a predetermined number, the control device dries the second eraser through the drying unit.

6. The tablet printing apparatus according to claim 2 or 3, characterized in that, It also includes a cleaning fluid supply unit that supplies the cleaning fluid to the first cleaner. At regular intervals, the control device supplies the wiping fluid from the wiping fluid supply unit to the first wiper.

Images