Tablet printing device

Abstract

To provide a tablet printing device capable of suppressing reduction in printing quality.SOLUTION: A tablet printing device 1 according to an embodiment includes: a transportation device 20 that transports a tablet T; an inkjet-type print head 51 that performs printing on a tablet T transported by the transportation device; a maintenance device 80 that performs maintenance of the print head 51; and a control device 90 that controls the print head 51 and the maintenance device 80. The control device 90 changes operation of the maintenance according to either one or both of a type of the tablet T to be transported and a type of an ink.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a tablet printing apparatus. [Background technology]

[0002] A technology is known that uses an inkjet print head to print identification information such as letters and symbols on tablets. A tablet printing device that uses this technology transports multiple tablets in a line on a conveyor, and ejects ink (e.g., edible ink) from the nozzles of an inkjet print head arranged above the conveyor toward the tablets that pass under the print head, thereby printing the identification information on the tablets on the conveyor.

[0003] Inkjet print heads are subjected to periodic maintenance to maintain their ejection performance, and are also subjected to maintenance to restore ejection performance when ejection defects occur. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-58220 A Summary of the Invention [Problem to be solved by the invention]

[0005] Tablets without a coating on the surface, such as plain tablets and OD (Orally Disintegrating) tablets (hereinafter simply referred to as plain tablets), generate powder when powder attached to the surface falls off or the surface is scraped off during transportation. The generated powder may adhere to the nozzle surface of the print head. If the nozzle is blocked by the powder attached to the nozzle surface, it will cause ejection problems. The occurrence of ejection problems leads to a decrease in print quality.

[0006] Therefore, it is necessary to perform efficient maintenance of the print head depending on the type of tablet.

[0007] The present invention aims to provide a tablet printing device that can prevent a decrease in print quality. [Means for solving the problem]

[0008] A tablet printing device according to an embodiment includes a transport device that transports tablets, an inkjet print head that prints by ejecting ink onto the tablets transported by the transport device, a maintenance device that performs maintenance on the print head, and a control device that controls the print head and the maintenance device, and the control device changes the maintenance operation depending on either or both of the type of the tablets or the type of the ink being transported. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing a schematic configuration of a tablet printing apparatus according to a first embodiment. [Diagram 2] FIG. 1 is a plan view showing a schematic configuration of a tablet printing apparatus according to a first embodiment. [Diagram 3] 1 is a diagram illustrating an example of a schematic configuration of a maintenance device according to a first embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of a schematic configuration of a control device according to the first embodiment. [Diagram 5] 4 is a flowchart showing a maintenance process according to the first embodiment. [Figure 6] FIG. 2 is an operation state diagram of the maintenance device according to the first embodiment. [Figure 7] FIG. 11 is a diagram for explaining an outline of a maintenance process according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <First embodiment> The first embodiment will be described with reference to FIGS.

[0011] (Example of tablet printing device configuration) As shown in Figures 1 and 2, the tablet printing apparatus 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 collection device 70, a maintenance device 80 (see Figure 2), and a control device 90.

[0012] The supply device 10 has a hopper 11 and a chute 12. The supply device 10 is positioned at one end side of the conveying device 20, and is configured to be able to supply tablets T, which are printing objects, to the conveying device 20. The hopper 11 stores a large number of tablets T, and sequentially supplies the stored tablets T to the chute 12. The chute 12 aligns the tablets T supplied from the hopper 11 in a line and supplies them to the conveying device 20. The supply device 10 is electrically connected to a control device 90, and its drive is controlled by the control device 90.

[0013] The conveying device 20 has 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 and is stretched over the driving pulley 22 and each driven pulley 23. The driving pulley 22 and each driven pulley 23 are rotatably provided 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 and is attached to the motor 24. This position detector 25 is electrically connected to the control device 90 and transmits a detection signal to the control device 90. The conveying device 20 rotates the conveying belt 21 together with each driven pulley 23 by the rotation of the driving pulley 22 by the motor 24, and conveys the tablets T on the conveying belt 21 in the rotation direction of the arrow H1 in FIG. 1, i.e., in the conveying direction H1.

[0014] A plurality of circular suction holes 21a (see FIG. 2) are formed in the conveyor belt 21. These suction holes 21a are through holes that suck the tablets T, and are arranged in two parallel rows along the conveying direction H1 to form two conveying paths. Each suction hole 21a is connected to the inside of the suction chamber 26 (see FIG. 1) through a suction path (not shown) formed in the suction chamber 26, and it is possible to obtain suction force from the suction chamber 26. A pump is connected to the suction chamber 26 through a suction pipe (not shown), and the inside of the suction chamber 26 is depressurized by the operation of the pump. The suction pipe is connected to approximately the center of the side surface (plane 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 drive is controlled by the control device 90. When the inside of the suction chamber 26 is depressurized, the tablets T placed on each suction hole 21a of the conveyor belt 21 are sucked by the suction hole 21a and held on the conveyor belt 21.

[0015] The detection device 30 includes a plurality of detection units 31 (two in this embodiment). The detection units 31 are positioned downstream in the conveying direction H1 from the position where the supply device 10 is provided, and are provided above the conveyor belt 21. The detection units 31 detect the position of the tablet T on the conveyor belt 21 in the X direction (see FIG. 2) by projecting and receiving laser light. For example, a displacement sensor or a proximity sensor is used as the detection unit 31. For example, various laser sensors such as a reflective laser sensor are used as the displacement sensor. The detection device 30 is electrically connected to the control device 90, and transmits a detection signal to the control device 90.

[0016] The first imaging device 40 includes a plurality of first imaging units 41 (two in this embodiment). The first imaging unit 41 is positioned downstream in the conveying direction H1 from the position where the detection device 30 is provided, and is provided 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 performs imaging at the timing when the tablet T reaches the imaging position directly below the first imaging unit 41, acquires a first image (image for tablet position detection) including the upper surface of the tablet T, and transmits the acquired first image to the control device 90. The first image is used to detect the positions of the tablet T in the X direction, Y direction, and θ direction. As the first imaging unit 41, various cameras having imaging elements such as a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) are used. The first imaging device 40 is electrically connected to the control device 90, and its drive is controlled by the control device 90. In addition, illumination for imaging is also provided as necessary.

[0017] Here, the positions of the tablet T in the X and Y directions are, for example, positions in the XY coordinate system relative to the center (reference position) of the imaging area of ​​the first imaging unit 41. The position in the θ direction is, for example, a 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. This position in the θ direction is detected when the tablet T has a shape having a directional property, such as when a score line is provided on the tablet T or when the tablet T is molded into an ellipse, an oval, a rectangle, or the like.

[0018] The printing device 50 has a print head 51 and an elevation mechanism 52. The print head 51 is positioned downstream in the transport direction H1 from the position where the first imaging device 40 is provided, and is provided above the transport belt 21. The print head 51 has a plurality of nozzles 51a (for example, several hundred to several thousand) (see FIG. 2), and is provided so that the direction in which the nozzles 51a are arranged in a row (nozzle row) is perpendicular (one example of intersection) to the transport direction H1 in a horizontal plane. Note that in FIG. 2, for the sake of simplicity, four nozzles 51a are shown. The print head 51 ejects ink from each nozzle 51a individually by the operation of a drive element for each nozzle 51a. As the print head 51, various inkjet type print heads having drive elements such as piezoelectric elements, heat elements, or magnetostrictive elements are used. The print head 51 can be raised and lowered by the elevation mechanism 52 (see FIG. 1) so as to approach or move away from the transport belt 21. The print head 51 is raised and lowered during maintenance of the print head 51. Maintenance of the print head 51 will be described later. The printing device 50 is electrically connected to a control device 90, and its drive is controlled by the control device 90.

[0019] The second imaging device 60 includes a plurality of second imaging units 61 (two in this embodiment). The second imaging unit 61 is positioned downstream in the conveying direction H1 from the position where the printing device 50 is provided, and is provided 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, an image is captured at the timing when the tablet T reaches the imaging position directly below the second imaging unit 61, a second image including the upper surface of the tablet T is obtained, and the obtained second image is transmitted to the control device 90. The second image is used to inspect the print pattern printed on the tablet T. As the second imaging unit 61, various cameras having an imaging element such as a CCD or CMOS are used, as in the first imaging unit 41 described above. The second imaging device 60 is electrically connected to the control device 90, and its drive is controlled by the control device 90. In addition, illumination for imaging is also provided as necessary.

[0020] The recovery device 70 is positioned downstream in the conveying direction H1 from the position where the second imaging device 60 is provided, and is provided at the end of the conveying device 20 on the downstream side in the conveying direction H1. The conveying device 20 releases the tablet T when the tablet T on the conveying belt 21 reaches a predetermined position, for example, the end of the conveying device 20 on the downstream side in the conveying direction H1. The recovery device 70 is configured to collect the tablets T that are released from the conveying device 20 and fall, separating them into defective and non-defective. For example, by blowing gas onto the tablets T in the middle of falling, and changing the falling direction of the tablets T for defective and non-defective, or by changing the falling path by a member such as a plate, it is possible to collect the tablets T that fall into defective and non-defective. For example, the defective tablets are tablets that fail printing, and the non-defective tablets are tablets that pass printing. The recovery device 70 is electrically connected to the control device 90, and its drive is controlled by the control device 90.

[0021] 2 and 3, the maintenance device 80 includes a liquid receiving unit 81, a suction unit 82, a wiper 83, and a movement mechanism 84. The maintenance device 80 is provided so as to be aligned with the print head 51 in the direction in which the nozzles 51a of the print head 51 are aligned in a plan view (Y direction in FIG. 2). Note that the movement mechanism 84 is omitted in FIG. 2 to simplify the illustration. Details of the maintenance device 80 will be described later.

[0022] During maintenance of the print head 51, the maintenance device 80 moves between the conveyor belt 21 and the print head 51 and cleans the underside (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.

[0023] The control device 90 controls each part of the tablet printing device 1, such as the supply device 10, the transport device 20, the detection device 30, the first imaging device 40, the printing device 50, the second imaging device 60, the recovery device 70, and the maintenance device 80, based on various information and various programs. The control device 90 also receives detection information (e.g., detection signals) transmitted from the position detector 25 and the detection device 30, and also receives image information transmitted from the first imaging unit 41 and the second imaging unit 61. The control device 90 is realized, for example, by an electronic circuit such as an integrated circuit or a computer.

[0024] Next, a configuration example of the control device 90 will be described with reference to FIG.

[0025] 4, the control device 90 has an image processing unit 91, a storage unit 92, and a control unit 93. An input device 90a and an output device 90b are connected to the control device 90. The input device 90a is realized by, for example, a switch, a touch panel, a keyboard, a mouse, etc. The output device 90b is realized by, for example, a display, a lamp, a meter, etc.

[0026] The image processing unit 91 captures the first image captured by the first imaging device 40 and the second image captured by the second imaging device 60, and processes the images using a known image processing technique. For example, the image processing unit 91 processes the first image obtained from the first imaging device 40, acquires the presence or absence of cracks, chips, and dirt on the tablet T, and further acquires the positions of the tablet T in the X direction, Y direction, and θ direction. The image processing unit 91 also processes the second image obtained from the second imaging device 60, and acquires the printing position, shape, and size of the printing pattern (e.g., letters and marks) printed on the tablet T. The image processing unit 91 transmits to the control unit 93 the acquired information on the presence or absence of cracks, chips, and dirt on the tablet T, the acquired position information on the X direction, Y direction, and θ direction of each tablet T, and further the printing position information, shape information, and size information of the printing pattern on each tablet T.

[0027] The storage unit 92 stores processing information, various programs, and the like. For example, it is realized by a semiconductor memory element such as a RAM (Random Access Memory) 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 to be printed, data on the ink used for printing, print data related to printing, data on the movement speed of the conveyor belt 21, and the like. The print data includes information on print patterns such as characters and marks.

[0028] The control unit 93 is, for example, a computer such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and controls each unit. For example, the control unit 93 controls the supply device 10, the transport device 20, the detection device 30, the first imaging device 40, the printing device 50, the second imaging device 60, the collection device 70, the maintenance device 80, the image processing unit 91, the storage unit 92, and the like, based on various information and various programs stored in the storage unit 92. The control unit 93 also receives detection signals transmitted from the detection device 30 and the position detector 25, and the like. The control unit 93 is realized, for example, by one or both of hardware and software.

[0029] For example, the control unit 93 acquires the position of the tablet T in the X direction on the conveyor belt 21 based on the detection information transmitted from the detection device 30, i.e., the timing at which the tablet T on the conveyor belt 21 was detected, and sets the imaging timing of the first imaging device 40, the print start timing of the print 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, generates timing information indicating these timings, and stores it in the storage unit 92. The print start timing is the timing at which printing is started on the tablet T that has reached the printing position directly below the print head 51. The control unit 93 can acquire information such as the movement amount (rotation amount) and speed of the conveyor belt 21 based on the detection information transmitted from the position detector 25.

[0030] Further, the control unit 93 sets whether or not printing is possible for the tablet T for which the presence / absence information has been obtained based on the presence / absence information of cracks, chips, and dirt on the tablet T transmitted from the image processing unit 91. Then, the control unit 93 sets printing conditions for the tablet T for which the presence / absence information has been obtained based on the position information of the tablet T in the X direction, Y direction, and θ direction transmitted from the image processing unit 91. For example, the control unit 93 determines the range of the nozzle 51a used for printing the target tablet T in the print head 51, that is, the nozzle range to be used, based on the position information of the tablet T in the Y direction and the printing data, and sets printing conditions including the nozzle range to be used and the timing of starting printing. In addition, when the tablet T has a shape having a directionality, 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 the θ direction. As an example, the control unit 93 registers 180 different printing patterns in the memory unit 92, in which the orientation of the printing pattern is rotated by 1 degree in a range from 0 degrees to 179 degrees, and selects from among these printing patterns a printing pattern with an angle that matches the position of the tablet T in the θ direction, and sets the printing conditions.

[0031] Furthermore, the control unit 93 judges whether or not the printed pattern has been printed in a predetermined shape and a predetermined size at a predetermined position on the tablet T, i.e., whether or not the printed pattern has been normally printed on the tablet T, based on the printing position information, shape information, and size information of the printed pattern printed on the tablet T transmitted from the image processing unit 91 (printing state inspection). For example, in judging the shape and size of the printed pattern, the control unit 93 registers a printing pattern for inspection in the memory unit 92, and compares the printing pattern for inspection with the printed pattern on the tablet T after actual printing (the printing pattern printed on the tablet T).

[0032] The control unit 93 appropriately stores various information (for example, information on the presence or absence of cracks, chips, and dirt on the tablet T, position information, timing information, printing conditions, print quality information, etc.) in the storage unit 92. When the target tablet T is collected by the collection device 70, for example, when the tablet T falls from the downstream end of the conveying device 20 in the conveying direction H1 and a predetermined time (for example, several seconds) has elapsed, the various information is deleted from the storage unit 92. However, if such information is required in a later process, it is possible to leave the various information for each tablet T without deleting it, or to store it in a storage medium outside the device. When storing the various information for each tablet T, this information may be linked to the manufacturing date and time, lot number, etc. and stored, so that when a defective product occurs after shipping for the printed tablet T, the cause can be traced back.

[0033] (Example of maintenance device configuration) Next, the configuration of the maintenance device 80 will be described with reference to Fig. 3. Fig. 3 is a diagram of the print head 51 and maintenance device 80 as viewed from the upstream side in the transport direction H1. As described above, the maintenance device 80 comprises the liquid receiving unit 81, the suction unit 82, the wiper 83, and the movement mechanism 84. When maintenance is not being performed, these are positioned so that, from the print head 51 side, the wiper 83, the suction unit 82, and the liquid receiving unit 81 are lined up in this order, and are provided so as to be movable as a unit by the movement mechanism 84.

[0034] The liquid receiving portion 81 is formed, for example, in a box shape that is open at the top. This liquid receiving portion 81 receives ink ejected from each nozzle 51a of the opposing print head 51 during maintenance of the print head 51. The length of the liquid receiving portion 81 in a direction perpendicular to the transport direction H1 is provided to be at least longer than the nozzle row in which the nozzles 51a are lined up. In the first embodiment, the length of the liquid receiving portion 81 in a direction perpendicular to the transport direction H1 is longer than two print heads 51 lined up (longer than the length of two print heads).

[0035] The suction unit 82 is a vacuum wiper having a slit-shaped suction port at its upper portion that extends in the transport direction H1. The length of the slit-shaped suction port is approximately the same as the length of the print head 51 in the transport direction H1. The suction unit 82 is connected to a suction pump (not shown). While the suction pump is operated, the suction unit 82 moves in a manner that scans the nozzle surface while in close proximity to the nozzle surface of the print head 51, thereby sucking up and removing ink adhering to the nozzle surface.

[0036] The wiper 83 wipes away and removes powder and ink adhering to the nozzle face by sliding in contact with the nozzle face of the print head 51. The wiper 83 has a first wiper 83a and a second wiper 83b.

[0037] The first wiper 83a has a liquid-absorbent fiber material, such as nonwoven fabric, on the upper part. The first wiper 83a is soaked with wiping liquid (e.g., an aqueous solution containing ethanol). In other words, the first wiper 83a is a wet wiper. The supply of wiping liquid to the first wiper 83a may be performed by an operator or may be automatically performed. By supplying the wiping liquid, the first wiper 83a is soaked with the wiping liquid.

[0038] The second wiper 83b has a liquid-absorbent fibrous material such as nonwoven fabric on its upper portion, similar to the first wiper 83a. The second wiper 83b is a dry wiper (no wiping liquid is supplied).

[0039] The movement 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 wiper 83 are fixed to the slider 84b, and the ball screw 84b is rotated by the motor 84c, so that the movement mechanism 84 can be moved between a maintenance position and a standby position. Here, the maintenance position is the position of the maintenance device 80 when maintenance is being performed on the print head 51, and is a position between the conveyor belt 21 and the print head 51. The standby position is the position of the maintenance device 80 when maintenance is not being performed, and is a position shifted from above the conveyor belt 21 (a position toward the back of the paper in FIG. 1).

[0040] (Printing process) Next, the printing process performed by the above-mentioned tablet printing device 1 will be described with reference to Fig. 1 and Fig. 2. This printing process also includes an inspection process. Various information such as data required for printing is stored in the storage unit 92 in advance.

[0041] When the tablet printing device 1 starts the printing process, the motor 24 is driven, and the conveyor belt 21 rotates in the conveying direction H1 in accordance with the rotation of the drive pulley 22 and the driven pulley 23 by the motor 24. With the conveyor belt 21 rotating in the conveying direction H1, the tablets T are sequentially supplied from the hopper 11 to the chute 12, and are arranged in a line by the chute 12 and supplied randomly, not at regular intervals, onto the conveyor belt 21. The tablets T supplied onto the conveyor belt 21 are lined up in two lines on the conveyor belt 21 and conveyed at a predetermined moving speed.

[0042] The tablet T on the conveyor belt 21 is detected by the detection device 30. In detail, the tablet T on the conveyor belt 21 is detected by the detection unit 31 at the timing when it reaches a detection position (e.g., a laser light irradiation position) directly below the detection unit 31 of the detection device 30, and the position of the tablet T in the X direction on the conveyor belt 21 is recognized by the control unit 93 based on the timing when the tablet T is detected. Then, position information indicating the position of the tablet T in the X direction is generated by the control unit 93 and stored in the memory unit 92.

[0043] Next, the tablet T on the conveyor belt 21 is imaged by the first imaging device 40. In detail, the tablet T on the conveyor belt 21 is imaged by the first imaging device 40 at the timing when it reaches the imaging position directly below the first imaging device 40, and the first image obtained by imaging by the first imaging device 40 is transmitted to the control device 90. Based on this first image, information on the presence or absence of cracks, chips, and dirt on the tablet T, as well as position information on the tablet T in the X direction, Y direction, and θ direction are generated by the image processing unit 91 and stored in the memory unit 92. Whether or not printing is possible on the target tablet T is set based on the information on the presence or absence of cracks, chips, and dirt on the tablet T, and based on information such as the position information in the X direction, Y direction, and θ direction of the tablet T and the printing pattern, printing conditions including the nozzle range to be used and the printing start timing for the tablet T set to printable (printable tablet T) are set in the memory unit 92. In addition, the ejection timing for the tablet T (the timing for ejecting ink onto the tablet T) is determined based on the above-mentioned printing start timing (the timing for starting printing on the tablet T).

[0044] Printing is performed by the printing device 50 based on these printing conditions. That is, the control unit 93 controls the printing head 51 of the printing device 50 to print a predetermined printing pattern on the printable tablets T on the conveyor belt 21. In detail, the printable tablets T on the conveyor belt 21 that have passed under the first imaging device 40 are printed by the printing head 51 based on the above-mentioned printing conditions at the print start timing when the tablets T reach the printing position directly below the printing head 51. In the printing head 51, ink is appropriately ejected from each nozzle 51a, and a printing pattern (for example, a number, an alphabet, a katakana character, a symbol, a figure) is printed on the printing surface, which is the upper surface of the tablet T. The ink applied to the tablet T dries during transportation. In addition, a drying unit (not shown) that dries by gas or heat may be provided, and the ink may be dried by the drying unit.

[0045] Thereafter, the printed tablets T on the conveyor belt 21 are imaged by the second imaging device 60. In detail, the printed tablets T on the conveyor belt 21 are imaged by the second imaging device 60 at the timing when the tablets T on the conveyor belt 21 reach an imaging position directly below the second imaging device 60, and the second image obtained by imaging by the second imaging device 60 is transmitted to the control device 90.

[0046] This second image is analyzed by the image processing unit 91 of the control device 90. In detail, information regarding the printed pattern printed on the tablet T, i.e., the printing position, shape, and size of the printed pattern, is acquired by the image processing unit 91. The second image transmitted from the second imaging device 60 is analyzed by the image processing unit 91, and inspection information indicating the printing position, shape, and size of the printed pattern printed on the tablet T is generated and stored in the memory unit 92.

[0047] Based on this inspection information, the control unit 93 executes a print status inspection. In detail, based on the inspection information related to the printing position, shape, and size stored in the memory unit 92, the control unit 93 judges whether the printing pattern has been normally printed on the tablet T, and print quality information indicating whether the tablet T is printed properly is generated and stored in the memory unit 92. For example, in the print status inspection, the printing pattern used for printing is stored in the memory unit 92 as a printing pattern for inspection, and non-defective product information related to the predetermined printing position, shape, and size of the printing pattern for inspection is compared with inspection information related to the printing position, shape, and size of the actually printed printing pattern stored in the memory unit 92, and it is judged whether the printing pattern has been normally printed on the tablet T (pass or fail).

[0048] Finally, the tablets T on the conveyor belt 21 are collected by the collection device 70. More specifically, when the inspected tablets T are positioned at the downstream end of the conveyor belt 21 as the conveyor belt 21 moves, they are released from the state held by the conveyor belt 21, drop from the conveyor belt 21, and are collected by the collection device 70. At this time, the tablets T that passed the inspection drop as they are and are collected by the collection device 70 as non-defective products, but the tablets T that were rejected or non-printed are separated from the non-defective products by blowing air on them as they fall from the conveyor belt 21, and are collected by the collection device 70 as defective products.

[0049] (Maintenance process) In a printing operation in which such a printing process is performed, the print head 51 is periodically maintained (for example, every 10 to 20 minutes). Maintenance methods include, for example, purging, wiping, and dummy ejection. Purging is an operation in which ink is pumped from the print head 51 toward the liquid receiving portion 81 while the liquid receiving portion 81 is facing the print head 51, thereby ejecting the ink from the print head 51 toward the liquid receiving portion 81. By performing the purging operation, air bubbles in the nozzles and ink that has dried and solidified can be removed, and ejection defects can be prevented. Wiping is an operation in which the nozzle surface of the print head 51 is sucked by the suction portion 82 or wiped by the wiper 83. By wiping, powder and ink attached to the nozzle surface can be removed, and ejection defects can be prevented. Dummy ejection is an operation (preliminary ejection operation) in which, while the liquid receiving portion 81 is facing the print head 51, the inkjet drive element is driven to eject a small amount of ink.

[0050] However, as mentioned above, when printing on plain tablets, powder may be generated and the generated powder may adhere to the nozzle surface. Usually, in the nozzle of an inkjet print head, the ink filled in the nozzle is adjusted to form a concave surface by a meniscus at the discharge port due to the head difference with the ink container connected to the print head. Therefore, when purging is performed, a part of the ink pushed out from the nozzle is drawn into the nozzle together with the powder adhering to the nozzle discharge port and the periphery of the discharge port in order to form the meniscus again. This may cause the nozzle to become clogged, resulting in poor discharge.

[0051] Therefore, if the tablet T to be printed is a plain tablet, in the maintenance of the print head 51, wiping is performed before purging (before the ejection operation is performed) to remove powder adhering to the nozzle surface. On the other hand, if the tablet T to be printed is a coated tablet (sugar-coated tablet, film-coated tablet, etc.) that does not generate (or generates little) powder, wiping does not need to be performed before purging. Details of such a maintenance process will be described below.

[0052] The maintenance process for the print head 51 is shown in Fig. 5. The process shown in Fig. 5 is executed by each unit under the control of the control device 90. The type of tablet T to be printed is input in advance by the operator via the input device 90a when starting the printing operation, and is stored in the memory unit 92. While the maintenance process is being carried out, the supply of tablets T by the supply device 10 is temporarily stopped.

[0053] First, a case where the tablet T to be printed is a coated tablet will be described. When it is time to perform maintenance on the print head 51, the lifting mechanism 52 is controlled to raise the print head 51 (step S101). This increases the distance between the conveyor belt 21 and the print head 51. At this time, the print head 51 rises to a height position where the lower surface of the print head 51 does 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 below.

[0054] Next, the movement mechanism 84 is controlled to position the liquid receiving portion 81 so that it faces the nozzle face of the print head 51. Furthermore, the lifting mechanism 52 is controlled to lower the print head 51 to a height where the nozzle face of the print head 51 does not come into contact with the suction portion 82 but comes into contact with the wiper 83 when wiped, as shown in Fig. 6 (step S102).

[0055] When the control device 90 determines that the tablet T is a coated tablet (step S103: No) based on information on the type of tablet T to be printed that has been input in advance by the operator via the input device 90a and stored in the memory unit 92, it pressurizes the ink in the print head 51 and performs a purging operation (step S104).

[0056] Next, the moving mechanism 84 is controlled to move the suction unit 82 and the wiper 83 to the left in Fig. 6. As a result, the print head 51 is subjected to vacuum wiping by the suction unit 82 (step S105), wet wiping by the first wiper 83a (step S106), and dry wiping by the second wiper 83b (step S107), in that order.

[0057] Once wiping is complete, the lifting mechanism 52 is controlled to lift the print head 51 (step S108). Once the print head 51 has lifted, the movement mechanism 84 is controlled to position the liquid receiving portion 81 so that it faces the nozzle face of the print head 51 (step S109). With the liquid receiving portion 81 and the nozzle face of the print head 51 facing each other, the inkjet driving elements of the print head 51 are driven to perform dummy ejection (step S110).

[0058] When the dummy discharge is completed, the movement mechanism 84 is controlled to move the maintenance device 80 (the suction unit 82 and the wiper 83) to the standby position (step S111), and the lifting mechanism 52 is controlled to lower the print head 51 to a height position for performing the printing operation (step S112). When the print head 51 is lowered, the maintenance process is completed. When the maintenance process is completed, the supply of tablets T by the supply device 10 is resumed, and the printing operation is performed.

[0059] Next, a case where the tablet T to be printed is an uncoated tablet will be described. When the time for maintenance of the print head 51 arrives, similar to the case of the coated tablet described above, the print head 51 rises (step S101), and when the liquid receiving section 81 is positioned in a position facing the nozzle surface of the print head 51, the print head 51 descends (step S102). After that, in step S103, based on the information on the type of the tablet T to be printed that is input in advance by the operator via the input device 90a and stored in the memory section 92, the control device 90 determines that the tablet T is an uncoated tablet (step S103: Yes), and proceeds to step S113 to perform wiping.

[0060] That is, the movement mechanism 84 is controlled to move the suction unit 82 and the wiper 83 toward the left in Fig. 6. As a result, the print head 51 is subjected to vacuum wiping by the suction unit 82 (step S113), wet wiping by the first wiper 83a (step S114), and dry wiping by the second wiper 83b (step S115), in that order. Powder adhering to the nozzle face of the print head 51 can be removed by this wiping.

[0061] When wiping is completed, the lifting mechanism 52 is controlled to lift the print head 51 (step S116). When the print head 51 has lifted, the movement mechanism 84 is controlled to position the liquid receiving portion 81 so as to face the nozzle face of the print head 51. Furthermore, the lifting mechanism 52 is controlled to lower the print head 51 to a height at which the wiper 83 comes into contact with the nozzle face of the print head 51 when wiping is performed, as shown in FIG. 6 (step S117).

[0062] Once the print head 51 has descended, the steps from step S104 onwards are executed in the same manner as when the tablets T are coated tablets described above.

[0063] As described above, according to the first embodiment, the tablet printing device 1 includes a conveying device 20 that conveys tablets T, an inkjet print head 51 that prints on the tablets T conveyed by the conveying device 20, a maintenance device 80 that performs maintenance on the print head 51, and a control device 90 that controls the print head 51 and the maintenance device 80, and the control device 90 changes the maintenance operation depending on the type of tablets T being conveyed. This allows efficient maintenance. Therefore, it is possible to prevent poor ejection and a decrease in print quality.

[0064] In the first embodiment, when the printing target is a plain tablet, wiping is performed before purging (before performing the ejection operation). By performing wiping, powder adhering to the nozzle surface can be removed. This makes it possible to prevent the powder from being drawn in when a part of the ink pushed out from the nozzle is drawn into the nozzle to form the meniscus again when purging is performed. Therefore, it is possible to prevent ejection failure from occurring and the print quality from deteriorating.

[0065] In the first embodiment, vacuum wiping is performed by the suction unit 82 before wet wiping by the first wiper 83a. During printing, powder may adhere to the nozzle surface and may also adhere to and mix with the ink adhered to the nozzle surface. By performing vacuum wiping before wet wiping, the powder mixed with the ink can also be removed. Ink that cannot be completely removed by vacuum wiping can be removed by wet wiping. Furthermore, after wet wiping by the first wiper 83a, dry wiping is performed by the second wiper 83b. Wiping liquid adhered to the nozzle surface by wet wiping can be removed by dry wiping. By such wiping, the print head 51 can be efficiently cleaned.

[0066] On the other hand, when the printing target is a coated tablet, there is no or very little powder adhesion to the nozzle surface, so wiping before purging is not necessary. Therefore, by performing maintenance on the print head, it is possible to prevent ejection problems while shortening the maintenance time.

[0067] <Second embodiment> Next, a second embodiment will be described. In the second embodiment, only the differences from the first embodiment will be described, and a description of the same points will be omitted.

[0068] Some inks for printing on tablets contain a fixing agent depending on the composition and the physical properties of the tablets to be printed.

[0069] The fixing agent may be, for example, a substance classified as a thickening agent, gum base, or thickening stabilizer. Specific examples include acetylated adipate crosslinked starch, acetylated oxidized starch, acetylated phosphate crosslinked starch, starch acetate, oxidized starch, hydroxypropyl starch, phosphate crosslinked starch, phosphorylated starch, and phosphate monoester crosslinked starch. Other examples include okra extract, seaweed cellulose, brown algae extract, gluten, gluten hydrolyzate, konjac extract, sweet potato cellulose, nata de coco, mannan, and rennet casein. In addition, Aureobasidium culture medium, Agrobacterium succinoglycan, Amaseed gum, Gum arabic, Arabinogalactan, Alginic acid, Welan gum, Elemi resin, Ozokerite, Cassia gum, Gatti gum, Curdlan, Carrageenan (processed Eucheuma algae, refined carrageenan, Eucheuma algae powder), Karaya gum, Carob bean gum, Xanthan gum, Chitin, Chitosan, Guar gum, Guar gum enzyme hydrolyzate, Guaiac resin, Guttahankan, Guttapercha, Glucosamine, Yeast cell wall, Psyllium seed gum, Sabaku mugwort seed gum, Shellac Shellac (white shellac, refined shellac), gellan gum, jelutong, sorba, sorbinha, tamarind seed gum, tara gum, chicle, chilte, tunu, low molecular weight gum, dextran, tragacanth gum, abelmoschus aureus, natto gum, niger gutta, paraffin wax, microfibrous cellulose, furcellaneous, aloe barbadensis extract, pullulan, powdered rice husk, pectin, Venezuelan chicle, macrophomopsis gum, mastic, massarandubarata, myrrh, peach resin, rhamsan gum, lech de vaca, levan, rosidinha, and rosin.

[0070] Ink containing a fixing agent can prevent the ink from peeling off or fading when printed. However, if the ink contains a fixing agent, the ink's viscosity increases and the ink's adhesion to the nozzle surface becomes strong when the ink dries and solidifies, so that the ink may not be sufficiently removed even by wiping.

[0071] Therefore, in the second embodiment, the amount of wiping liquid supplied to the first wiper 83a (wet wiper) and the number of dots during dummy ejection are changed depending on whether or not the ink supplied to the print head 51 contains a fixer (type of ink). An outline of the second embodiment is shown in FIG.

[0072] Information on the ink used for printing is input in advance by an operator to the control device 90 via the input device 90a. Before starting the printing operation of the tablet printing device 1 or before starting the maintenance process, wiping liquid is supplied to the first wiper 83a. At this time, if the ink contains a fixing agent, the amount of wiping liquid supplied is made larger than when the ink does not contain a fixing agent. Also, in the dummy ejection in the maintenance process (step S110 in FIG. 5), if the ink contains a fixing agent, the number of dummy ejections (number of dots) is made larger than when the ink does not contain a fixing agent.

[0073] The support member supporting the first wiper 83a may be in the shape of a box-shaped container with an open top, and the wiping liquid may be stored therein. In this case, a part of the lower side (the side opposite to the side that contacts the nozzle surface) of the first wiper 83a is immersed in the wiping liquid stored in the container, so that the first wiper 83a can be kept wet for a long time. In addition to 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 (support member of the first wiper 83a). The amount of wiping liquid contained in the first wiper 83a can also be changed by changing the volume of the part of the first wiper 83a that is immersed in the wiping liquid.

[0074] As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained. Furthermore, in the second embodiment, the amount of wiping liquid supplied to the first wiper 83a is changed depending on whether or not the ink contains a fixing agent. More specifically, when the ink contains a fixing agent, the amount of wiping liquid supplied to the first wiper 83a is increased. This results in the ink being wiped away by the first wiper 83a containing a large amount of wiping liquid. Therefore, even if the ink contains a fixing agent, the ink adhering to the nozzle surface can be easily removed by dissolving the ink.

[0075] In addition, when wet wiping is performed, wiping liquid seeps out from the first wiper 83a due to the pressure when the nozzle surface and the first wiper 83a come into contact with each other. Some of the seeping wiping liquid may enter the nozzle. If the wiping liquid enters the nozzle, the ink in the nozzle becomes diluted. If the first wiper 83a contains a large amount of wiping liquid, the amount of wiping liquid that seeps out may also increase, and the amount of wiping liquid that enters the nozzle may also increase. Therefore, when wiping is performed in a state in which the first wiper 83a contains a large amount of wiping liquid, the number of times (the number of dots) that the ink is discharged is increased in the dummy discharge. By performing the dummy discharge, the wiping liquid that has entered the nozzle can be discharged. This makes it possible to prevent the ink from becoming thin and the visibility of the printed identification information from becoming poor when the printing operation is resumed thereafter.

[0076] <Other embodiments> In the above description, two print heads 51 are provided, but one or three or more may be provided. Also, one maintenance device 80 may be provided for one print head 51, or one maintenance device 80 may be shared by multiple print heads 51.

[0077] Further, although the liquid receiving portion 81, the suction portion 82, and the wiper 83 are shown as being moved integrally in the above embodiment, the present invention is not limited to this and each of them may be provided so as to be movable independently.

[0078] Also, although an example has been given in which the wiper 83, suction unit 82, and liquid receiving unit 81 are moved by the moving mechanism 84 so as to face the print head 51, this is not limiting. For example, the print head 51 may be moved, or both the print head 51 and the maintenance device may be moved. In other words, it is sufficient to configure the print head 51 and the maintenance device 80 to move relative to each other.

[0079] Furthermore, when the supply of wiping liquid to the first wiper 83a is to be performed automatically, a wiping liquid supply unit may be provided to the first wiper 83a. By providing the wiping liquid supply unit, the amount of wiping liquid supplied to the first wiper 83a can be changed by controlling the wiping liquid supply unit depending on whether the ink contains a fixing agent or does not contain a fixing agent.

[0080] Furthermore, a wiping liquid supply unit (not shown) may be provided separately from the first wiper 83a, and wiping liquid may be periodically supplied to the first wiper 83a. The amount of wiping liquid periodically supplied may be changed depending on the type of ink. For example, when ink containing a fixing agent is used, the amount of wiping liquid supplied to the first wiper 83a may be increased. Alternatively, the frequency of supplying wiping liquid to the first wiper 83a may be increased.

[0081] Also, a wet state detection sensor that detects the amount of wiping liquid contained in the first wiper 83a (the wet state of the first wiper 83a) may be provided. The wet state detection sensor transmits a detection value to the control device 90. The control device 90 can determine the wet state of the first wiper 83a based on the detection value transmitted from the wet state detection sensor. The control device 90 may control to change the number of dummy discharges based on the determination result. Alternatively, the relationship between the elapsed time after the supply of wiping liquid to the first wiper 83a or the number of wipings and the wet state may be obtained in advance by experiments or the like, and the wet state of the first wiper 83a at the timing of wiping may be determined based on this, and the number of dummy discharges may be controlled to be changed.

[0082] In addition, when the tablet T to be printed is a plain tablet, the powder is removed by wiping before purging, but the method of removing the powder is not limited to this. For example, a cleaning liquid may be directly supplied to the nozzle surface of the print head 51. In other words, it is sufficient as long as the powder adhering to the nozzle surface can be removed.

[0083] Moreover, the second wiper 83b may be, for example, a blade, as long as it can remove the wiping liquid (cleaning liquid) adhering to the nozzle surface.

[0084] In addition, although the information on the ink used for printing is input to the control device 90 by the operator via the input device 90a, this is not limiting. For example, the tablet printing device 1 may be equipped with an RF tag reading unit, and when an ink container (bottle or cartridge) is attached to the tablet printing device 1, the RF tag attached to the ink container may be read to obtain the ink information. Also, a barcode or two-dimensional code may be attached to the ink container, and the ink information may be input to the tablet printing device 1 by reading this.

[0085] The amount of wiping liquid supplied to the first wiper 83a may be adjusted according to the composition of the ink. For example, it may be adjusted according to the type and content of the fixing agent. The number of dummy ejections may be changed according to the amount of wiping liquid supplied to the first wiper 83a. In other words, the number of dummy ejections may be increased as the amount of wiping liquid increases.

[0086] In addition, in the dummy ejection, the number of ejections is changed depending on whether or not the ink contains a fixing agent, but this is not limiting. For example, the ejection amount for each ejection in the dummy ejection may be changed. In addition, both the number of ejections and the ejection amount may be changed.

[0087] In addition, the above-mentioned maintenance process is exemplified as being performed periodically during printing operation, but is not limited to this, and may be performed when ejection defects of the nozzles 51a or printing defects are detected based on the second image. By performing the maintenance process, the ejection performance of the print head 51 can be restored.

[0088] In addition, in the above-mentioned maintenance process, the speed of wiping by the first wiper 83a and the second wiper 83b was not specifically mentioned, but the moving speed of the first wiper 83a and the second wiper 83b (the speed at which the wiper 83 slides on the nozzle surface of the print head 51) may be controlled by controlling the moving mechanism 84. For example, the control unit 93 may count the number of times the print head 51 is wiped, and when the number of times exceeds a predetermined number, the moving speed of the moving mechanism 84 may be reduced to reduce the moving speed of the first wiper 83a and the second wiper 38b. Alternatively, the control unit 93 may measure the time from the start of operation of the tablet printing device 1, and determine that the number of times of wiping by the wiper 83 has exceeded the predetermined number due to the passage of a predetermined time, thereby reducing the moving speed of the moving mechanism 84 to reduce the moving speed of the first wiper 83a and the second wiper 83b. As the operation time of the print head 51 increases, ink may also adhere to the nozzle surface of the print head 51 and accumulate. However, by reducing the movement speed of the moving mechanism 84 by the control unit 93, the wiping liquid held in the first wiper 83a in particular is sufficiently supplied to the nozzle surface of the print head 51, and the ink adhered to the nozzle surface can be suitably removed. The speed may be gradually reduced from the start of operation of the tablet printing device 1, not only when the wiping exceeds a predetermined number of times or when a predetermined time has elapsed. The wiping speed may be reduced only for either the first wiper 83a or the second wiper 83b, and the wiping liquid may be sufficiently supplied to the nozzle surface of the print head 51 by reducing the movement speed of only the first wiper 83a, and the adhered ink may be removed. In this case, it is preferable to configure the first wiper 83a and the second wiper 83b to be able to move independently. For example, one of the first wiper 83a and the second wiper 83b may be moved by the moving mechanism 84, and the other may be moved by a different moving mechanism (in the same direction as the moving mechanism 84).

[0089] In addition, the second wiper 83b is a dry wiper, but as the operation time increases, the second wiper 83b gradually becomes wet by absorbing the ink adhering to the nozzle surface of the print head device 51 and the wiping liquid supplied from the first wiper 83a. Therefore, a drying unit (not shown) for drying the second wiper 83b may be provided, and the control unit 93 may dry the second wiper 83b by the drying unit, for example, when the number of wipings by the wiper 83 exceeds a predetermined number of times, or when the operation time of the tablet printing device 1 has elapsed for a predetermined time. The drying unit is preferably one that dries the second wiper 83b by ejecting drying gas in a direction 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, which causes the ink in the nozzle 51a to solidify and lead to printing defects. The drying unit may supply drying gas from a drying section that dries the ink applied to the tablet T through a pipe (not shown), for example. The flow rate of the drying gas supplied from the drying unit to the second wiper 83b may be gradually increased. In other words, the amount of the drying gas supplied by the drying unit may be increased each time the number of wiping operations by the second wiper 83b increases, so that the second wiper 83b is dried more reliably.

[0090] Here, the above-mentioned tablet T can include tablets used for medicine, food, cleaning, industrial or aromatic purposes. In addition, the tablet T can be a plain tablet (plain tablet), a sugar-coated tablet, a film-coated tablet, an enteric-coated tablet, a gelatin-coated tablet, a multi-layered tablet, a dry-coated tablet, etc., and various capsule tablets such as hard capsules and soft capsules can also be included in the tablet T. Furthermore, the shape of the tablet T can be a disk shape, a lens shape, a triangle shape, an oval shape, etc. In addition, when the tablet T to be printed is for medicine or food, an edible ink is preferably used as the ink to be used. As the edible ink, any of a synthetic pigment ink, a natural pigment ink, a dye ink, and a pigment ink can be used.

[0091] Although several embodiments of the present invention have been described above, these embodiments are presented 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, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0092] 1 Tablet printing equipment 10 Feeding device 20. Conveyor 21 Conveyor belt 30 Detection Device 40 First imaging device 50 Printing device 51 Print Head 60 Second imaging device 70 Recovery Device 80 Maintenance Equipment 81 Liquid receiving part 82 Suction part 83 Wiper 83a First Wiper 83b Second Wiper 84 Moving mechanism 90 Control device T Tablet

Claims

1. A conveying device for conveying tablets; an inkjet print head that ejects ink onto the tablets transported by the transport device to perform printing; a maintenance device for performing maintenance on the print head; A control device that controls the print head and the maintenance device; Equipped with The control device changes the maintenance operation depending on either the type of the tablet being transported or the type of the ink, or both.

2. The maintenance device includes a wiper that wipes a nozzle surface of the print head; a liquid receiving portion that receives ink ejected from the print head; having The tablet printing device according to claim 1 , wherein the control device controls the maintenance device to perform the wiping and then to purge the print head when the tablet being transported is a plain tablet.

3. The tablet printing apparatus according to claim 2 , wherein the control device controls the maintenance device so as not to perform the wiping before performing purging when the tablets being transported are coated tablets.

4. The wiper is a first wiper that is a wet wiper supplied with wiping liquid; a second wiper that is a dry wiper; The tablet printing apparatus according to claim 2 or 3, further comprising:

5. The tablet printing device according to claim 4 , wherein the control device controls to change either the number of times or the amount of dummy ejection by the print head depending on the amount of wiping liquid supplied to the first wiper.

6. the maintenance device further includes a suction unit that sucks the nozzle surface, The tablet printing apparatus according to claim 4 , wherein, in the wiping, the print head is subjected to suction by the suction unit, wiping by the first wiper, and wiping by the second wiper in this order.

7. The tablet printing apparatus according to claim 4, characterized in that the control device reduces the wiping speed of at least one of the first wiper and the second wiper when the number of wipings by the first wiper and the second wiper exceeds a predetermined number.

8. a drying unit for drying the second wiper; 5. The tablet printing apparatus according to claim 4, wherein the control device dries the second wiper by the drying unit when the number of wiping operations by the second wiper exceeds a predetermined number.

9. a wipe liquid supply unit that supplies the wipe liquid to the first wiper, 5. The tablet printing apparatus according to claim 4, wherein the control device supplies the wiping liquid from the wiping liquid supply unit to the first wiper every time a predetermined time elapses.

10. The tablet printing device according to claim 9 , wherein the control device changes the amount of the wiping liquid supplied from the wiping liquid supply unit to the first wiper or the frequency of supplying the wiping liquid depending on the type of ink.

Images