TW202415553A - Tablet printing device capable of preventing deterioration of printing quality - Google Patents

Abstract

The present invention provides a tablet printing device capable of preventing deterioration of printing quality. The tablet printing device (1) according to an embodiment includes a conveying device (20) for conveying a tablet (T); a printing head (51) of an inkjet type for performing printing on the tablet (T) conveyed by the conveying device; a maintenance device (80) for performing maintenance on the printing head (51); and a control device (90) for controlling the printing head (51) and the maintenance device (80). The control device (90) changes operation of maintenance according to one or both of the type of the tablet (T) to be conveyed or the type of ink.

Description

Tablet printing device

An embodiment of the present invention relates to a tablet printing device.

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

In order to maintain the ejection performance of an inkjet print head, the print head is regularly maintained. In addition, when an ejection failure occurs, the print head is also maintained to restore the ejection performance. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2019-58220

[Problem to be solved by the invention]

Tablets that are not coated on the surface, such as uncoated tablets or orally disintegrating (OD) tablets (hereinafter referred to as uncoated tablets), generate powder due to the falling of powder attached to the surface or the grinding of the surface during transportation. The generated powder sometimes adheres to the nozzle surface of the print head. If the nozzle is clogged due to the powder attached to the nozzle surface, it will cause poor ejection. The occurrence of poor ejection leads to reduced printing quality.

Therefore, efficient print head maintenance is required according to the type of tablet.

The purpose of the present invention is to provide a tablet printing device that can prevent the reduction of printing quality. [Technical means for solving the problem]

The tablet printing device of the embodiment includes: a conveying device for conveying tablets; a printing head for printing by jetting ink on the tablets conveyed by the conveying device; a maintenance device for maintaining the printing head; and a control device for controlling the printing head and the maintenance device, wherein the control device changes the maintenance action according to either or both of the type of the tablet to be conveyed or the type of the ink.

<First Implementation Form> The first implementation form is described with reference to Figures 1 to 6.

(Structural example of tablet printing device) As shown in FIG1 and FIG2, the tablet printing device 1 of the first embodiment includes a supply device 10, a conveying device 20, a detection device 30, a first imaging device 40, a printing device 50, a second imaging device 60, a recovery device 70, a maintenance device 80 (see FIG2) and a control device 90.

The supply device 10 has a hopper 11 and a chute 12. The supply device 10 is located at one end of the conveying device 20 and is configured to supply a sheet T as a printing object to the conveying device 20. The hopper 11 contains a plurality of sheets T and sequentially supplies the contained sheets T to the chute 12. The chute 12 arranges the sheets T supplied from the hopper 11 in a row and supplies them to the conveying device 20. The supply device 10 is electrically connected to the control device 90, and its driving is controlled by the control device 90.

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

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

The detection device 30 includes a plurality of detection units 31 (two in the present embodiment). The detection unit 31 is located on the downstream side of the supply device 10 in the conveying direction H1 and is disposed above the conveyor belt 21. The detection unit 31 detects the position of the tablet T on the conveyor belt 21 in the X direction (refer to FIG. 2 ) by projecting and receiving light by laser. As the detection unit 31, for example, a displacement sensor or a proximity sensor is used. In addition, as the displacement sensor, for example, various laser sensors such as a reflection type laser sensor are used. The detection device 30 is electrically connected to the control device 90 and sends a detection signal to the control device 90.

The first imaging device 40 includes a plurality of first imaging units 41 (two in the present embodiment). The first imaging unit 41 is located on the downstream side of the installation position of the detection device 30 in the conveying direction H1, and is installed above the conveyor belt 21. The first imaging unit 41 takes a picture based on the position information of the tablet T in the X direction detected by the detection device 30, at the time of the tablet T reaching the imaging position directly below the first imaging unit 41, and obtains a first image (image for tablet position detection) including the upper surface of the tablet T, and transmits the obtained first image to the control device 90. The first image is used to detect the position of the tablet T in the X direction, the Y direction, and the θ direction. Various cameras having an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) are used as the first imaging unit 41. The first imaging device 40 is electrically connected to the control device 90, and its driving is controlled by the control device 90. In addition, lighting for imaging is also provided as needed.

Here, the positions of the sheet T in the X direction and the Y direction 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. In addition, the position in the θ direction is, for example, a position indicating the degree of rotation of the sheet T relative to the center line in the Y direction of the imaging area of the first imaging unit 41. When the sheet T is a shape having directionality, such as when a dividing line is provided in the sheet T or when the sheet T is formed into an ellipse, an oblong, a quadrilateral, etc., the position in the θ direction is detected.

The printing device 50 has a printing head 51 and a lifting mechanism 52. The printing head 51 is located on the downstream side of the conveying direction H1 relative to the installation position of the first camera 40, and is installed above the conveying belt 21. The printing head 51 has a plurality of (e.g., hundreds to thousands) nozzles 51a (refer to FIG. 2), and is installed in a manner that the direction in which the nozzles 51a are arranged in a row (nozzle row) is orthogonal to the conveying direction H1 in the horizontal plane (an example of crossing). In addition, in FIG. 2, in order to simplify the figure, the nozzles 51a are shown as four. The printing head 51 ejects ink from each nozzle 51a individually through the operation of the driving element of each nozzle 51a. As the print head 51, various inkjet print heads having a driving element such as a piezoelectric element, a heating element, or a magnetostrictive element are used. The print head 51 can be lifted and lowered in a manner approaching or leaving the conveyor belt 21 by a lifting mechanism 52 (see FIG. 1 ). The lifting and lowering movement of the print head 51 is performed during the maintenance of the print head 51. The maintenance of the print head 51 will be described later. The printing device 50 is electrically connected to the control device 90, and its driving is controlled by the control device 90.

The second imaging device 60 includes a plurality of second imaging units 61 (two in the present embodiment). The second imaging unit 61 is located on the downstream side of the installation position of the printing device 50 in the conveying direction H1, and is installed above the conveying belt 21. The second imaging unit 61 takes a picture 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, and obtains a second image including the upper surface of the tablet T at the imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 61, and transmits the obtained second image to the control device 90. The second image is used to inspect the printed pattern printed on the tablet T. As the second imaging unit 61, various cameras having imaging elements such as CCD or CMOS are used, similarly to the first imaging unit 41. The second imaging device 60 is electrically connected to the control device 90, and its driving is controlled by the control device 90. In addition, lighting for imaging is also provided as needed.

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

As shown in FIG. 2 and FIG. 3 , the maintenance device 80 includes a liquid receiving portion 81, a suction portion 82, an eraser 83, and a moving mechanism 84. The maintenance device 80 is arranged side by side with the print head 51 in the direction in which the nozzles 51 a of the print head 51 are arranged in a plan view (the Y direction in FIG. 2 ). In addition, in FIG. 2 , the moving mechanism 84 is omitted for simplification. The details of the maintenance device 80 will be described later.

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 driving is controlled by the control device 90.

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

Next, a configuration example of the control device 90 will be described with reference to FIG. 4 .

As shown in FIG4 , 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 by, for example, a switch, a touch screen, a keyboard, a mouse, etc. In addition, the output device 90b is implemented by, for example, a display, a lamp, a meter, etc.

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

The storage unit 92 stores processing information or various programs, etc. For example, it is realized by a semiconductor memory element such as a random access memory (RAM), a flash memory (Flash Memory), or a storage device such as a hard disk or an optical disk. In the storage unit 92, the type data of the tablet as the printing object, the data of the ink used in the printing, the printing data related to the printing, the moving speed data of the conveyor belt 21, etc. are stored. The printing data includes information of the printing pattern such as text or mark.

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

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

In addition, the control unit 93 sets whether the sheet T having the information of cracks, notches, or dirt is printed, based on the information of whether the sheet T has cracks, notches, or dirt sent from the image processing unit 91. Furthermore, the control unit 93 sets printing conditions for the sheet T set to be printable. At this time, the control unit 93 sets printing conditions for the sheet T having the position information in the X direction, Y direction, and θ direction sent from the image processing unit 91. For example, the control unit 93 determines the range of the nozzles 51a used in the printing of the target sheet T in the print head 51, that is, the nozzle range, based on the position information in the Y direction of the sheet T or the printing data, and sets printing conditions including the nozzle range or the printing start timing. Furthermore, when the tablet T has a directional shape, the control unit 93 sets the printing conditions corresponding to the position in the θ direction of the tablet T based on the position information in the θ direction of the tablet T. As an example, the control unit 93 registers 180 printing patterns obtained by rotating the orientation of the printing pattern by one degree at a time within the range of 0 to 179 degrees in the storage unit 92, and selects a printing pattern with an angle suitable for the position in the θ direction of the tablet T from these printing patterns to set the printing conditions.

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

In addition, the control unit 93 appropriately stores various information (e.g., information on whether the tablet T has cracks or notches, dirt, or position information, timing information, printing conditions, printing quality information, etc.) in the storage unit 92, but when the target tablet T is collected by the collection device 70, for example, at a time point after a predetermined time (e.g., several seconds) has passed since the tablet T falls from the end on the downstream side of the conveying direction H1 in the conveying device 20, the various information is deleted from the storage unit 92. However, if such information is required in a subsequent process, etc., the various information of each tablet T may be retained without being deleted, or may be stored in a storage medium outside the device. When various information of each tablet T is stored in advance, the information can be stored in association with the manufacturing date and time or the batch number, so that the printed tablet T can be traced back to the situation where a defective product is produced after shipment and the cause can be investigated.

(Structural example of maintenance device) Next, the structure of the maintenance device 80 is described with reference to FIG3. FIG3 is a diagram of the print head 51 and the maintenance device 80 when viewed from the upstream side of the conveying direction H1. As described above, the maintenance device 80 includes a liquid receiving portion 81, a suction portion 82, an eraser 83, and a moving mechanism 84. When not performing maintenance, they are positioned in the order of the eraser 83, the suction portion 82, and the liquid receiving portion 81 from the print head 51 side, and are arranged to be able to be moved as a whole by the moving mechanism 84.

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

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

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

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

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

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

(Printing process) Next, the printing process performed by the tablet printing device 1 is described with reference to FIG. 1 and FIG. 2. The printing process also includes an inspection process. In addition, various information such as data required for printing is pre-stored in the storage unit 92.

When the tablet printing device 1 starts printing, the motor 24 is driven, and the conveyor belt 21 rotates in the conveying direction H1 as the driving pulley 22 and the driven pulley 23 are rotated by the motor 24. While the conveyor belt 21 rotates in the conveying direction H1, the tablets T are sequentially supplied from the hopper 11 to the chute 12, and are arranged in a row through the chute 12 and are randomly supplied to the conveyor belt 21 without fixed intervals. The tablets T supplied to the conveyor belt 21 are transported at a predetermined moving speed while being arranged in two rows on the conveyor belt 21.

The tablet T on the conveyor belt 21 is detected by the detection device 30. Specifically, the detection unit 31 detects the tablet T on the conveyor belt 21 when the tablet T reaches the detection position (e.g., laser light 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 recognizes 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.

Next, the first camera 40 photographs the tablet T on the conveyor belt 21. Specifically, the first camera 40 photographs the tablet T on the conveyor belt 21 when the tablet T reaches the photographing position directly below the first camera 40, and the first image obtained by the first camera 40 is sent to the control device 90. Based on the first image, the image processing unit 91 generates information on whether the tablet T has cracks or notches, dirt, and position information of the tablet T in the X direction, Y direction, and θ direction, and stores the information in the storage unit 92. Based on the information of whether the sheet T has cracks, notches, or dirt, it is set whether printing can be performed on the target sheet T. In addition, based on the position information of the sheet T in the X direction, Y direction, and θ direction or the information of the printed pattern, the printing conditions including the nozzle range used for the sheet T set to be printable (printable sheet T) or the printing start timing are set in the storage unit 92. In addition, based on the printing start timing (the timing of starting printing on the sheet T), the ejection timing of the sheet T (the timing of ejecting ink on the sheet T) is determined.

Based on the printing conditions, the printing device 50 performs printing. 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 sheet T on the conveyor belt 21. Specifically, at the printing start timing when the printable sheet T on the conveyor belt 21 that has passed under the first camera 40 reaches the printing position directly under the printing head 51, the printing is performed by the printing head 51 based on the printing conditions. In the printing head 51, ink is appropriately ejected from each nozzle 51a to print a printing pattern (for example, a number, a letter, a katakana, a symbol, a figure) on the upper surface of the sheet T, i.e., the printed surface. The ink applied on the sheet T dries during the conveyance process. In addition, a drying section (not shown) for drying using gas or heat may be provided, and the ink may be dried by the drying section.

Thereafter, the second camera 60 photographs the printed sheet T on the conveyor belt 21. Specifically, the second camera 60 photographs the printed sheet T on the conveyor belt 21 when the printed sheet T reaches the photographing position directly below the second camera 60, and the second image photographed by the second camera 60 is sent to the control device 90.

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

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

Finally, the sheet T on the conveyor belt 21 is recovered by the recovery device 70. Specifically, when the inspected sheet T is located at the end of the downstream side of the conveyor belt 21 as the conveyor belt 21 moves, it is released from the state of being held on the conveyor belt 21, falls from the conveyor belt 21, and is recovered by the recovery device 70. At this time, the sheet T that is a qualified sheet falls directly and is recovered as a good product by the recovery device 70, but the sheet T that is a defective sheet or a non-printed sheet is separated from the good products by the blowing of air in the middle of falling from the conveyor belt 21 and is recovered as a defective product by the recovery device 70.

(Maintenance process) During the printing operation of this printing process, the print head 51 is maintained regularly (for example, every 10 minutes to 20 minutes). Maintenance methods include cleaning, wiping, and virtual ejection. The so-called cleaning refers to the action of ejecting ink from the print head 51 toward the liquid receiving portion 81 by pressurizing the ink while the liquid receiving portion 81 and the print head 51 are facing each other. By performing the cleaning action, bubbles in the nozzle or dried and solidified ink can be removed, thereby preventing poor ejection. The so-called erasing refers to the action of sucking the nozzle surface of the print head 51 using the suction portion 82 or wiping it using the eraser 83. By wiping, powder or ink attached to the nozzle surface can be removed, thereby preventing poor ejection. The so-called virtual ejection refers to the action of driving the ink ejection drive element to eject a small amount of ink (pre-ejection action) when the liquid receiving part 81 and the print head 51 are facing each other.

However, as mentioned above, when printing on a non-clothing sheet, powder may be generated, and the generated powder may adhere to the nozzle surface. Usually, in the nozzle of the inkjet printing head, the ink filled in the nozzle is adjusted to form a concave surface through the meniscus at the nozzle outlet by the water level difference of the ink container connected to the printing head. Therefore, when cleaning, part of the ink squeezed out of the nozzle is collected in the nozzle along with the powder attached to the nozzle outlet and the surrounding of the nozzle in order to form the meniscus again. Therefore, the nozzle is clogged, which may cause poor ejection.

Therefore, when the tablet T to be printed is a plain tablet, in the maintenance of the print head 51, wiping is performed before cleaning (before the ejection operation) to remove the powder attached to the nozzle surface. On the other hand, when the tablet T to be printed is a coated tablet (sugar-coated tablet, film-coated tablet, etc.) that does not (or rarely) generate powder, wiping is not performed before cleaning. The details of this maintenance process are described below.

FIG5 shows the maintenance process of the print head 51. The process shown in FIG5 is a process executed by each unit under the control of the control device 90. The type of the tablet T to be printed is input by the operator via the input device 90a in advance when the printing operation starts, and is stored in the storage unit 92. During the maintenance process, the supply of the tablet T by the supply device 10 is temporarily stopped.

First, the case where the tablet T to be printed is a coated tablet will be described. When the time for maintenance of the print head 51 comes, the lifting mechanism 52 is controlled to raise the print head 51 (step S101). As a result, the distance between the conveyor belt 21 and the print head 51 increases. At this time, the print head 51 rises to a height position where the lower surface of the print head 51 does not contact the suction part 82 and the eraser 83 even if the suction part 82 and the eraser 83 are moved as described later.

Next, the moving mechanism 84 is controlled so that the liquid receiving portion 81 is positioned to face the nozzle surface of the print head 51. Furthermore, the lifting mechanism 52 is controlled so that the print head 51 is lowered to a height where the nozzle surface of the print head 51 does not abut against the suction portion 82 but abuts against the eraser 83 when erasing is performed, as shown in FIG. 6 (step S102).

If the control device 90 determines that the tablet T is a coated tablet based on information on the type of tablet T as the printing object previously input by the operator via the input device 90a and stored in the storage unit 92 (step S103: No), the ink in the printing head 51 is pressed and cleared (step S104).

Next, the moving mechanism 84 is controlled to move the suction unit 82 and the eraser 83 toward the left in Fig. 6. Thus, the print head 51 is sequentially subjected to vacuum erasure by the suction unit 82 (step S105), wet erasure by the first eraser 83a (step S106), and dry erasure by the second eraser 83b (step S107).

After the erasing is completed, the lifting mechanism 52 is controlled to raise the print head 51 (step S108). When the print head 51 is raised, the moving mechanism 84 is controlled to position the liquid receiving portion 81 to face the nozzle surface of the print head 51 (step S109). When the liquid receiving portion 81 faces the nozzle surface of the print head 51, the ink-ejecting drive element of the print head 51 is driven to perform virtual ejection (step S110).

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

Next, the case where the tablet T to be printed is a bare tablet will be described. When the maintenance time of the print head 51 is reached, the print head 51 is raised (step S101) in the same manner as the coated tablet, and after the liquid receiving portion 81 is positioned at a position facing the nozzle surface of the print head 51, the print head 51 is lowered (step S102). Thereafter, in step S103, if the control device 90 determines that the tablet T is a bare tablet based on the type information of the tablet T to be printed that has been previously input by the operator through the input device 90a and stored in the storage unit 92 (step S103: Yes), the control device 90 proceeds to step S113 to perform erasure.

That is, the moving mechanism 84 is controlled to move the suction unit 82 and the eraser 83 to the left in Fig. 6. Thus, the print head 51 is sequentially subjected to vacuum erasure by the suction unit 82 (step S113), wet erasure by the first eraser 83a (step S114), and dry erasure by the second eraser 83b (step S115). The above-mentioned erasure can remove the powder attached to the nozzle surface of the print head 51.

After erasing is completed, the lifting mechanism 52 is controlled to raise the print head 51 (step S116). After the print head 51 is raised, the moving mechanism 84 is controlled to position the liquid receiving portion 81 to face the nozzle surface of the print head 51. Furthermore, the lifting mechanism 52 is controlled to lower the print head 51 to a height at which the eraser 83 contacts the nozzle surface of the print head 51 when erasing is performed, as shown in FIG. 6 (step S117).

After the printing head 51 is lowered, the steps after step S104 are performed in the same manner as when the tablet T is a coated tablet.

As described above, according to the first embodiment, the sheet printing device 1 includes: a conveying device 20 for conveying a sheet T; a printing head 51 for printing the sheet T conveyed by the conveying device 20 using an inkjet method; a maintenance device 80 for maintaining the printing head 51; and a control device 90 for controlling the printing head 51 and the maintenance device 80. The control device 90 changes the maintenance operation according to the type of the sheet T to be conveyed. Thus, maintenance can be performed efficiently. Therefore, it is possible to prevent the occurrence of poor ejection and the reduction of printing quality.

In addition, in the first embodiment, when the printing object is a non-clothing piece, wiping is performed before cleaning (before the ejection operation). By wiping, the powder attached to the nozzle surface can be removed. Therefore, when cleaning is performed, it is possible to prevent the powder from being taken in when a part of the ink extruded from the nozzle is taken in to the nozzle to form a meniscus again. Therefore, it is possible to prevent the occurrence of ejection defects and the reduction of printing quality.

In addition, in the first embodiment, vacuum erasing is performed by the suction section 82 before wet erasing is performed by the first eraser 83a. Due to the printing operation, powder sometimes adheres to the nozzle surface, and the powder also adheres to and mixes with the ink attached to the nozzle surface. By performing vacuum erasing before wet erasing, the powder mixed in the ink can be removed at the same time. The ink that is not completely removed by vacuum erasing can be removed by wet erasing. Furthermore, after wet erasing is performed by the first eraser 83a, dry erasing is performed by the second eraser 83b. The erasing liquid attached to the nozzle surface due to wet erasing can be removed by dry erasing. By such erasing, the print head 51 can be cleaned efficiently.

On the other hand, when the printed object is a coated tablet, there is no or very little powder attached to the nozzle surface, so there is no need to wipe it off before cleaning. Therefore, by performing maintenance on the print head, it is possible to prevent poor ejection and shorten maintenance time.

<Second Implementation Form> Next, the second implementation form will be described. In the second implementation form, only the differences from the first implementation form will be described, and the description of the same points will be omitted.

The ink used for printing on the tablet may contain a fixing material depending on its composition or the physical properties of the tablet as the printing object.

The so-called fixing material may be, for example, a substance classified as a paste or a gelatin base, or a thickening stabilizer. Specifically, there are acetylated adipic acid cross-linked starch, acetylated oxidized starch, acetylated phosphate cross-linked starch, acetic acid starch, oxidized starch, hydroxypropyl starch, phosphate cross-linked starch, phosphate oxidized starch, phosphate monoesterified phosphate cross-linked starch, etc. In addition, there are okra extract, seaweed fiber, brown algae extract, gluten protein, gluten protein decomposition product, konjac extract, sweet potato fiber, coconut fruit, mannan, rennet casein, etc. In addition, there are Aureobasidium culture medium, Agrobacterium succinoglycan, linseed gum, gum arabic, arabinogalactan, alginic acid, welan gum, balsam resin, ground wax, cassia gum, ghatti gum, curdlan, carrageenan (processed Eucheuma algae, refined carrageenan, Eucheuma algae powder), karaya gum, locust bean gum, xanthan gum, chitin, chitosan, guar gum, guar gum hydrolysate, guaiac resin, gutta hang kang, and eucommia gum. percha), glucosamine, yeast cell wall, psyllium seed gum, wormwood seed gum, wormwood gum (white wormwood gum, refined wormwood gum), gellan gum, jelutong gum, sorva gum, sorvinha, tamarind seed gum, tara gum, chicle gum, chilte gum, tunu gum, low molecular rubber, glucan, tragacanth gum, okra root fungus, natto gum, Niger Eucommia gum gutta), wax, microfiber cellulose, red algae gel, cystine extract, pullulan, powdered husk, pectin, Venezuelan chicle, Macrophophopsis gum, mastic, Massaranduba balata, myrrh, peach gum, rhamsan gum, Leche de vaca extract, levan, rosidinha, glycosides, etc.

Ink containing a fixing agent can prevent the ink from peeling off or becoming thinner due to friction during printing. However, if a fixing agent is contained, the viscosity of the ink increases, or the adhesion to the nozzle surface becomes stronger when it dries and solidifies, and sometimes the ink cannot be fully removed even if it is wiped off.

Therefore, in the second embodiment, the amount of erasing liquid supplied to the first eraser 83a (wet eraser) and the number of dots during virtual ejection are changed according to whether the ink supplied to the print head 51 contains a fixing agent (ink type). The outline of the description of the second embodiment is shown in FIG.

Information on the ink used in printing is inputted to the control device 90 by the operator via the input device 90a in advance. Before starting the printing operation of the tablet printing device 1 or before starting the maintenance process, the erasing liquid is supplied to the first eraser 83a. At this time, when the ink contains a fixing agent, the amount of the erasing liquid supplied is increased compared to the case where the fixing agent is not contained. In addition, in the virtual ejection (step S110 of FIG. 5 ) in the maintenance process, when the ink contains a fixing agent, the number of virtual ejections (dots) is increased compared to the case where the fixing agent is not contained.

In addition, the supporting member supporting the first eraser 83a may be in the shape of a box-shaped container with an opening at the top, and the erasing liquid may be stored therein. In this case, by immersing a portion of the lower side of the first eraser 83a (the side opposite to the side abutting against the nozzle surface) in the erasing liquid stored in the container, the first eraser 83a can be kept wet for a long time. In addition, in addition to increasing the amount of erasing liquid supplied to the first eraser 83a, the amount of erasing liquid contained in the first eraser 83a can also be increased by increasing the capacity of the container (the supporting member of the first eraser 83a). In addition, by changing the volume of the portion of the first eraser 83a immersed in the erasing liquid, the amount of erasing liquid contained in the first eraser 83a can be changed.

As described above, according to the second embodiment, the same effect as the first embodiment can be obtained. Furthermore, in the second embodiment, the amount of erasing liquid supplied to the first eraser 83a is changed according to whether the ink contains a fixing agent. More specifically, when the ink contains a fixing agent, the amount of erasing liquid supplied to the first eraser 83a is increased. Thus, the first eraser 83a containing a large amount of erasing liquid can be used for wiping. Therefore, even if the ink contains a fixing agent, the ink is dissolved, so that the ink attached to the nozzle surface can be easily removed.

In addition, when wet erasing is performed, due to the pressure when the nozzle surface abuts against the first eraser 83a, the erasing liquid seeps out from the first eraser 83a. A portion of the seeping erasing liquid sometimes enters the nozzle. If the erasing liquid enters the nozzle, the ink in the nozzle becomes thinner. If the amount of erasing liquid contained in the first eraser 83a is large, the amount of erasing liquid that seeps out also increases, and the amount of erasing liquid that enters the nozzle sometimes increases. Therefore, when the first eraser 83a is erased in a state where a large amount of erasing liquid is contained, the number of times (points) of the ejection is increased in the virtual ejection. By performing virtual ejection, the erasing liquid that has entered the nozzle can be discharged. This can prevent the ink from becoming thinner and the visibility of the printed identification information from becoming poor when the printing operation is subsequently restarted.

<Other embodiments> In the above description, two print heads 51 are provided, but it may be one, or three or more. In addition, 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.

In addition, although the case where the liquid receiving part 81, the suction part 82, and the eraser 83 move integrally is illustrated, the present invention is not limited to this, and they may be configured to be able to move independently.

In addition, the eraser 83, the suction unit 82, and the liquid receiving unit 81 are shown as examples in which the eraser 83, the suction unit 82, and the liquid receiving unit 81 are moved in a manner opposite to the printing head 51 by the moving mechanism 84, but the present invention is not limited to this. For example, the printing head 51 may be moved, or both the printing head 51 and the maintenance device may be moved. In other words, it is sufficient as long as the printing head 51 and the maintenance device 80 are configured to move relative to each other.

In addition, when the erasing liquid is automatically supplied to the first erasing device 83a, it is sufficient to provide an erasing liquid supply unit on the first erasing device 83a. If the erasing liquid supply unit is provided, the amount of the erasing liquid supplied to the first erasing device 83a can be changed when the ink contains a fixing agent and when the ink does not contain a fixing agent by controlling the erasing liquid supply unit.

In addition, it is also possible to set up an erasing liquid supply unit (not shown) separately from the first erasing device 83a, and regularly supply the erasing liquid to the first erasing device 83a. The amount of the erasing liquid regularly supplied can be changed according to the type of ink. For example, when using ink containing a fixing agent, the amount of the erasing liquid supplied to the first erasing device 83a can be increased. Alternatively, it is also possible to increase the frequency of supplying the erasing liquid to the first erasing device 83a.

In addition, a wetness detection sensor for detecting the amount of erasing liquid contained in the first eraser 83a (wetness of the first eraser 83a) may be provided. The wetness detection sensor sends the detection value to the control device 90. The control device 90 may determine the wetness of the first eraser 83a based on the detection value sent from the wetness detection sensor. The control device 90 may control based on the determination result to change the number of virtual spraying times. Alternatively, the relationship between the time after the erasing liquid is supplied to the first eraser 83a or the number of erasures and the wetness state may be determined in advance through experiments, and based on this, the wetness state of the first eraser 83a at the time of erasing may be determined, and control may be performed to change the number of virtual ejections.

In addition, when the tablet T to be printed is a non-coated tablet, the example of removing the powder by wiping before cleaning is given, but the method of removing the powder is not limited to this. For example, it is also possible to directly supply the cleaning liquid to the nozzle surface of the printing head 51. That is, as long as the powder attached to the nozzle surface can be removed.

In addition, the second eraser 83b only needs to be capable of removing the eraser liquid (cleaning liquid) adhering to the nozzle surface, and may be, for example, a scraper.

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

In addition, the amount of the erasing liquid supplied to the first erasing device 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 fixing agent. In addition, the number of virtual ejections can be changed according to the amount of the erasing liquid supplied to the first erasing device 83a. That is, it can be set so that the number of virtual ejections increases as the amount of the erasing liquid increases.

In addition, although the example of changing the number of ejections in virtual ejection according to whether the ink contains a fixing agent is shown, the present invention is not limited to this. For example, the ejection amount of each ejection in virtual ejection may be changed. In addition, both the number of ejections and the ejection amount may be changed.

In addition, the maintenance process is illustrated as being performed regularly during printing operation, but the present invention is not limited thereto, and may be performed when the ejection of the ejection nozzle 51a is poor or when printing is poorly detected based on the second image. If the maintenance process is performed, the ejection performance of the print head 51 can be restored.

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

In addition, the second eraser 83b is a dry eraser, but as the operation time becomes longer, the second eraser 83b gradually gets wet by absorbing the ink attached to the nozzle surface of the print head 51 or the erasing liquid supplied from the first eraser 83a. Therefore, it is possible to set a drying unit (not shown) for drying the second eraser 83b, and the control unit 93 dries the second eraser 83b through the drying unit, for example, when the number of erasures performed by the eraser 83 exceeds a prescribed number of times or when the operation time of the tablet printing device 1 has passed a prescribed time. The drying unit preferably dries the second eraser 83b by ejecting a drying gas in a direction away from the nozzle surface of the print head 51. This is to prevent the following situation: the nozzle surface of the print head 51 is dried by the drying gas, and the ink of the nozzle 51a is solidified, resulting in poor printing. The drying unit can be set, for example, to supply the drying gas from the drying part that dries the ink applied to the tablet T through a pipe not shown. The drying gas supplied from the drying unit to the second eraser 83b can be set to gradually increase the flow rate. That is, it can be set to increase the supply amount of the drying gas supplied by the drying unit every time the number of erasures performed by the second eraser 83b increases, so that the second eraser 83b can be dried more reliably.

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

Several embodiments of the present invention have been described above, but these embodiments are only 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 can be omitted, replaced, changed, and combined in various ways without departing from the subject matter of the invention. These embodiments or their variations are included in the scope or subject matter of the invention and are included in the invention described in the claims and their equivalents.

1: Tablet printing device 10: Supply device 11: Hopper 12: Slideway 20: Conveyor device 21: Conveyor belt 21a: Suction hole 22: Driving pulley 23: Driven pulley 24, 84c: Motor 25: Position detector 26: Suction chamber 30: Detection device 31: Detection unit 40: First imaging device 41: First imaging unit 50: Printing device 51: Printing head 51a: Nozzle 52: Lifting mechanism 60: Second imaging device 61: Second imaging unit 70: Recovery device 80: Maintenance device 81: Liquid receiving unit 82: Suction unit 83: Eraser 83a: First eraser 83b: Second eraser 84: Moving mechanism 84a: Ball screw 84b: Slider 90: Control device 90a: Input device 90b: Output device 91: Image processing unit 92: Storage unit 93: Control unit H1: Arrow/transport direction S101, S102, S103, S104, S105, S106, S107, S108, S109, S110, S111, S112, S113, S114, S115, S116, S117: Steps T: Tablet X, Y, Z, θ: Direction

FIG. 1 is a front view showing a schematic structure of a tablet printing device of the first embodiment. FIG. 2 is a plan view showing a schematic structure of a tablet printing device of the first embodiment. FIG. 3 is a diagram showing an example of a schematic structure of a maintenance device of the first embodiment. FIG. 4 is a diagram showing an example of a schematic structure of a control device of the first embodiment. FIG. 5 is a flow chart showing a maintenance process of the first embodiment. FIG. 6 is an operation state diagram of the maintenance device of the first embodiment. FIG. 7 is a diagram for explaining an outline of a maintenance process of the second embodiment.

1: Tablet printing device

10: Supply device

11: Hopper

12: Slideway

20: Transport device

21: Conveyor belt

22: Drive pulley

23: Driven pulley

24: Motor

25: Position detector

26: Suction chamber

30: Detection device

31: Testing Department

40: First camera device

41: First camera unit

50: Printing device

51: Printing head

52: Lifting mechanism

60: Second camera device

61: Second camera unit

70: Recovery device

90: Control device

H1: Arrow/Transportation direction

T: Tablets

X, Y, Z: direction

Claims (10)

A tablet printing device comprises: a conveying device for conveying tablets; a printing head for printing by jetting ink on the tablets conveyed by the conveying device; a maintenance device for maintaining the printing head; and a control device for controlling the printing head and the maintenance device, wherein the control device changes the maintenance action according to either or both of the type of the tablet to be conveyed or the type of the ink. The tablet printing device as described in claim 1, wherein the maintenance device has: an eraser for erasing the nozzle surface of the printing head; and a liquid receiving portion for receiving the ink ejected from the printing head, and when the tablet to be transported is a non-coated tablet, the control device controls the maintenance device to perform the erasing and then clears the tablet from the printing head. The tablet printing device according to claim 2, wherein, when the tablet to be conveyed is a coated tablet, the control device controls the maintenance device so as not to perform the erasing before clearing. The tablet printing device as described in claim 2 or 3, wherein, the eraser comprises: a first eraser which is a wet eraser supplied with an erasing liquid; and a second eraser which is a dry eraser. A tablet printing device as described in claim 4, wherein the control device performs control in a manner that changes either or both of the number of ejections or the ejection amount of virtual ejection performed by the print head according to the amount of the erasing liquid supplied to the first eraser. The tablet printing device as described in claim 4, wherein the maintenance device further includes a suction unit, and the suction unit further sucks the nozzle surface. During the erasing, the print head is processed in the order of suction by the suction unit, erasing by the first eraser, and erasing by the second eraser. The tablet printing device as described in claim 4 is characterized in that when the number of erasing times using the first eraser and the second eraser exceeds a specified number, the control device reduces the speed of erasing by at least either the first eraser or the second eraser. The tablet printing device as described in claim 4 is characterized in that it also has a drying unit, which dries the second eraser. When the number of erasures performed by the second eraser exceeds a specified number, the control device dries the second eraser through the drying unit. The tablet printing device as described in claim 4 is characterized in that it also has an erasing liquid supply unit, which supplies the erasing liquid to the first eraser. Every time a specified time passes, the control device supplies the erasing liquid from the erasing liquid supply unit to the first eraser. The tablet printing device as described in claim 9 is characterized in that the control device changes the amount of the erasing liquid supplied from the erasing liquid supply section to the first eraser or the supply frequency of the erasing liquid according to the type of the ink.

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