Tablet printing device and tablet printing method

Abstract

The present invention provides a tablet printing device and a tablet printing method that can effectively eliminate defects of the tablet printing device while preventing the printing efficiency from decreasing. The present invention includes: a conveying unit that conveys tablets; an inkjet head that prints the tablets conveyed by the conveying unit; a maintenance unit for the inkjet head; a moving unit that moves the inkjet head in a direction orthogonal to the conveying direction of the tablets conveyed by the conveying unit; a camera unit that photographs the printed tablets; an image processing unit that processes the image photographed by the camera unit; and a calculation unit that calculates the yield rate of the tablets based on the image processed by the image processing unit, and when the yield rate calculated by the calculation unit is lower than a specified value, the maintenance unit performs maintenance on the inkjet head, and when the maintenance of the inkjet head by the maintenance unit exceeds a specified number of times, the inkjet head is moved by the moving unit.

Description

Technical Field

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

[0002] In order to print identification information (an example of information) such as text or marks on tablets, a technology for printing using an inkjet head is known. A tablet printing device using such a technology transports tablets using a conveyor such as a conveyor, and ejects ink from each nozzle of the inkjet head arranged above the conveyor toward the tablet passing under the inkjet head, thereby printing identification information on the tablet.

[0003] In addition, such tablet printing apparatuses may sometimes cause problems such as the ink not being ejected normally from the inkjet head, and thus may sometimes produce defective tablets.

[0004] When such defective tablets are produced, it is necessary to stop the entire operation of the tablet printing device, identify the cause, and eliminate the cause, thereby reducing printing efficiency.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 7-081050 Summary of the invention

[0008] [Problems to be solved by the invention]

[0009] An object of the present invention is to provide a tablet printing device and a tablet printing method that can effectively eliminate defects of the tablet printing device while preventing a decrease in printing efficiency.

[0010] [Technical means to solve the problem]

[0011] The tablet printing device of the embodiment is characterized in that it includes: a conveying unit for conveying tablets; an inkjet head for printing the tablets conveyed by the conveying unit; a maintenance unit for the inkjet head; a moving unit for moving the inkjet head in a direction orthogonal to the conveying direction in which the tablets are conveyed by the conveying unit; a camera unit for photographing the tablets printed by the inkjet head; an image processing unit for processing the image photographed by the camera unit; and a calculation unit for calculating the yield rate of the tablets based on the image processed by the image processing unit, when the yield rate calculated by the calculation unit is lower than a specified value, performing maintenance on the inkjet head by the maintenance unit, and when the maintenance of the inkjet head by the maintenance unit exceeds a specified number of times, using the moving unit to move the inkjet head to change the nozzle of the inkjet head used in printing the tablets.

[0012] The tablet printing method of the embodiment is characterized in that it includes: a printing process, using an inkjet head to print on the conveyed tablets; a camera process, photographing the tablets after printing in the printing process; a calculation process, calculating the yield rate of the tablets based on the image captured in the camera process; a maintenance process, when the yield rate is lower than a specified value, the inkjet head is maintained; and a moving process, when the number of maintenance of the inkjet head exceeds a specified number, the inkjet head is moved in a direction orthogonal to the conveying direction of the tablets.

[0013] [Effects of the Invention]

[0014] According to the embodiment of the present invention, it is possible to provide a tablet printing device that can effectively eliminate defects of the tablet printing device while preventing a decrease in printing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an overall side view of the tablet printing device according to the first embodiment of the present invention.

[0016] Figure 2 It is a plan view of the conveying unit according to the first embodiment of the present invention.

[0017] Figure 3 This is a block diagram of a control unit according to the first embodiment of the present invention.

[0018] Figure 4 This is a flowchart of the printing process according to the first embodiment of the present invention.

[0019] Explanation of symbols

[0020] 1: Tablet printing device

[0021] 10: Supply Department

[0022] 11: Hopper

[0023] 12: Slide

[0024] 13: Arrangement feeder

[0025] 14: Transfer feeder

[0026] 20: Transport Department

[0027] 21: Conveyor belt

[0028] 21a: Suction hole

[0029] 22: Driving pulley

[0030] 23: Driven pulley

[0031] 24: Motor

[0032] 25: Position detector

[0033] 26: Suction chamber

[0034] 30: Inspection Department

[0035] 40: First Camera Department

[0036] 50: Printing Department

[0037] 51: Inkjet head

[0038] 51a: Nozzle

[0039] 52: Mobile Department

[0040] 60: Second Camera Department

[0041] 70: Recycling Department

[0042] 80: Control device

[0043] 80a: Input device

[0044] 80b: Output device

[0045] 81: Image processing department

[0046] 82: Storage

[0047] 83: Control unit (computing unit)

[0048] 84: Counter

[0049] 90: Maintenance Department

[0050] 100: Cleaning Department

[0051] 101: Rotation axis

[0052] 102: Brush

[0053] 130: Box

[0054] H1: Transport direction (arrow)

[0055] S1~S10:Process

[0056] T: Tablet

[0057] A1, A2, X, Y, θ: Direction DETAILED DESCRIPTION

[0058] <First embodiment>

[0059] Reference Figures 1 to 4 A first embodiment will be described.

[0060] (Configuration Example of Tablet Printing Device)

[0061] like Figure 1 and Figure 2 As shown, the tablet printing device 1 of the first embodiment includes a supply unit 10, a conveying unit 20, a detection unit 30, a first imaging unit 40, a printing unit 50, a second imaging unit 60, a collection unit 70, a control device 80, a maintenance unit 90, and a cleaning unit 100.

[0062] The supply unit 10 includes: a hopper 11, a chute 12, an arrangement feeder 13, and a delivery feeder 14. The supply unit 10 is located at one end side of the conveying unit 20, and is configured to be able to supply tablets T as printing objects to the conveying unit 20. The hopper 11 accommodates a plurality of tablets T, and sequentially supplies the accommodated tablets T to the chute 12. The chute 12 is a structure in which an exciter is provided on a conveying path, and the tablets T supplied from the hopper 11 are conveyed by vibration, and are supplied to the arrangement feeder 13. The arrangement feeder 13 arranges the tablets T in a row and supplies them to the delivery feeder 14. The delivery feeder 14 sequentially supplies the tablets T arranged in a row to the conveying unit 20. The supply unit 10 is electrically connected to the control device 80, and its drive is controlled by the control device 80.

[0063] The conveying section 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 disposed 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 80, and its driving is controlled by the control device 80. 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 80, and sends a detection signal to the control device 80. In the conveying section 20, the conveying belt 21 and each driven pulley 23 rotate together due to the rotation of the driving pulley 22 caused by the motor 24, so that the tablets T on the conveying belt 21 are moved to the conveying chamber 26. Figure 1 The conveyor is conveyed in the rotation direction of the arrow H1 in FIG.

[0064] The conveyor belt 21 is formed with a plurality of circular suction holes 21a (see Figure 2 ). The suction holes 21a are through holes for adsorbing the tablets T, and are arranged in a row along the conveying direction H1 to form a conveying path. Each suction hole 21a is formed in a suction chamber 26 (see Figure 1) is connected to the inside of the suction chamber 26, so that suction force can be obtained through the suction chamber 26. The suction chamber 26 is connected to a pump (not shown) via a suction pipe, and the suction chamber 26 is depressurized by the operation of the pump. The suction pipe is connected to the approximate center of the side surface (the surface parallel to the conveying direction H1) of the suction chamber 26. In addition, the pump is electrically connected to the control device 80, and its driving is controlled by the control device 80. When the inside of the suction chamber 26 is depressurized, the tablets T placed on the suction holes 21a of the conveyor belt 21 are sucked by the suction holes 21a and held on the conveyor belt 21.

[0065] The detection unit 30 is located on the downstream side of the supply unit 10 in the conveying direction H1 and is provided above the conveyor belt 21. The detection unit 30 detects the X direction (refer to Figure 2 ) is detected. As the detection unit 30, for example, a displacement sensor or a proximity sensor is used. In addition, as the displacement sensor, for example, various laser sensors such as a reflective laser sensor are used. The detection unit 30 is electrically connected to the control device 80 and sends a detection signal to the control device 80.

[0066] The first imaging unit 40 is located on the downstream side of the conveying direction H1 relative to the installation position of the detection unit 30, and is installed above the conveyor belt 21. The first imaging unit 40 takes a picture at a first imaging timing when the tablet T reaches the imaging position directly below the first imaging unit 40 based on the position information of the tablet T in the X direction detected by the detection unit 30, obtains a first image including the upper surface of the tablet T, and sends the obtained first image to the control device 80. The first image is used to detect the X direction, Y direction and θ direction of the tablet T (refer to Figure 2 ) is detected. As the first imaging unit 40, various cameras having imaging elements such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) are used. The first imaging unit 40 is electrically connected to the control device 80, and its driving is controlled by the control device 80. In addition, lighting for imaging is also provided as needed.

[0067] Here, the position of the tablet T in the X direction and the Y direction is, for example, the position in the XY coordinate system relative to the center (reference position) of the imaging area of ​​the first imaging unit 40. In addition, the position in the θ direction is, for example, the position indicating the degree of rotation of the tablet T relative to the center line in the Y direction of the imaging area of ​​the first imaging unit 40. When the tablet T has a directional shape, such as when a dividing line is provided in the tablet T or when the tablet T is formed into an ellipse, an oblong, a quadrilateral, etc., the position in the θ direction is detected.

[0068] The printing unit 50 includes an inkjet head 51. The inkjet head 51 is located downstream of the first imaging unit 40 in the conveying direction H1 and is disposed above the conveyor belt 21. The inkjet head 51 has a plurality of (e.g., hundreds to thousands of) nozzles 51a (see Figure 2 ), and is arranged 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 (an example of intersection) in the horizontal plane. The inkjet head 51 is arranged so as to be movable in the direction in which the nozzles 51a are arranged (a direction orthogonal to the conveying direction H1) by means of a moving portion 52. The inkjet head 51 ejects ink from each nozzle 51a individually through the action of a driving element of each nozzle 51a. As the inkjet head 51, a printing head of various inkjet methods having a driving element such as a piezoelectric element, a heating element, or a magnetostrictive element is used. The inkjet head 51 and its moving portion 52 are electrically connected to the control device 80, and the drive thereof is controlled by the control device 80.

[0069] The second camera unit 60 is located at the downstream side of the conveying direction H1 more than the setting position of the printing unit 50, and is arranged above the conveyor belt 21. Based on the position information of the tablet T in the X direction detected by the detection unit 30, the second camera unit 60 takes a picture at the second shooting timing when the tablet T reaches the shooting position directly below the second camera unit 60, obtains a second image including the upper surface of the tablet T, and sends the obtained second image to the control device 80. The second image is used to check the printed pattern printed on the tablet T. As the second camera unit 60, various cameras having a camera element such as a CCD or CMOS are used, similarly to the first camera unit 40. The second camera unit 60 is electrically connected to the control device 80, and its drive is controlled by the control device 80. Lighting for shooting is also provided as needed.

[0070] The recovery unit 70 is located at the downstream side of the conveying direction H1 more than the setting position of the second camera unit 60, and is set at the end of the downstream side of the conveying direction H1 in the conveying unit 20. The conveying unit 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 unit 20. The recovery unit 70 is configured to recover the tablets T that have been released from the holding by the conveying unit 20 and have fallen into defective products and good products. For example, by blowing gas to the tablets T that are falling, the falling direction of the tablets T is changed according to defective products and good products, or by using components such as plates to change the falling path, the fallen tablets T can be divided into defective products and good products for recovery. For example, defective products are unqualified printing tablets, and good products are qualified printing tablets. The recovery unit 70 is electrically connected to the control device 80, and its drive is controlled by the control device 80.

[0071] The control device 80 controls each unit of the tablet printing device 1, such as the supply unit 10 or the conveying unit 20, the detection unit 30, the first imaging unit 40, the printing unit 50, the second imaging unit 60, the recovery unit 70, the maintenance unit 90, the cleaning unit 100, etc., based on various information and various programs. In addition, the control device 80 receives detection information (such as a detection signal) sent from the position detector 25 or the detection unit 30, and receives image information sent from the first imaging unit 40 or the second imaging unit 60. The control device 80 is implemented by, for example, an electronic circuit such as an integrated circuit or a computer.

[0072] The maintenance unit 90 is used to perform maintenance on the inkjet head 51. The maintenance unit 90 is used to maintain the inkjet head 51 below and not in contact with the inkjet head 51. Figure 1 The position where the nozzle 51a near the front side of the paper in the drawing is interfered is set as the standby position, and the position covering all the nozzles 51a is set as the maintenance position. The length of the long side direction of the maintenance unit 90 is a length greater than the length of the arrangement of the nozzles 51a of the inkjet head 51. When the maintenance unit 90 performs maintenance on the inkjet head 51, it moves from the standby position to the maintenance position using a moving device not shown in the figure. The maintenance unit 90 is a known maintenance mechanism for an inkjet head having a drain pan (drain pan) and a scraper (not shown). The ink pumped from an ink bottle (not shown) is ejected from the nozzle 51a to the drain pan, and the ink is wiped off using a scraper, etc., to perform maintenance on the inkjet head 51.

[0073] The cleaning section 100 is disposed at a position downstream of the recovery section 70 in the conveying direction H1 (below the suction chamber 26), and has a brush 102 that can rotate around a rotation axis 101. The rotation axis 101 is configured to be movable between a standby position and a cleaning position by a moving mechanism (not shown). The standby position is a position where the brush 102 is not in contact with the conveyor belt 21, and the cleaning position is a position where the brush 102 is in contact with the conveyor belt 21. The rotation direction of the brush 102 is clockwise and is the same as the rotation direction of the conveyor belt 21 (the conveying direction H1). The conveyor belt 21 that moves on the lower side of the suction chamber 26 rotates clockwise. Figure 1 Therefore, although the rotation direction of the brush 102 is the same as the conveying direction H1, the moving direction of the conveying belt 21 at the position in contact with the brush 102 is opposite to the rotation direction of the brush 102 (refer to Figure 1 In addition, a box capable of storing powder removed from the surface of the conveyor belt 21 may be provided below the brush 102.

[0074] (Configuration Example of Control Device)

[0075] Below, refer to Figure 3 A configuration example of the control device 80 will be described.

[0076] like Figure 3 As shown, the control device 80 includes: an image processing unit 81, a storage unit 82, a control unit 83, and a counter 84. The control device 80 is connected to an input device 80a or an output device 80b. The input device 80a is implemented by, for example, a switch or a touch screen, a keyboard, a mouse, etc. In addition, the output device 80b is implemented by, for example, a display, a lamp, a meter, etc.

[0077] The image processing unit 81 imports the first image captured by the first camera unit 40 and the second image captured by the second camera unit 60, and processes the images using known image processing techniques. For example, the image processing unit 81 processes the first image obtained from the first camera unit 40 to obtain the position of the tablet T in the X direction, Y direction, and θ direction. In addition, the image processing unit 81 processes the second image obtained from the second camera unit 60 to obtain the printing position, shape, and size of the printed pattern (for example, text or mark) printed on the tablet T. The image processing unit 81 sends the obtained position information of each tablet T in the X direction, Y direction, and θ direction, and the printing position information, shape information, and size information of the printed pattern on each tablet T to the control unit 83.

[0078] The storage unit 82 stores processing information or various programs. For example, it is realized by a semiconductor memory element such as a random access memory (RAM) or a flash memory or a storage device such as a hard disk or an optical disk. The storage unit 82 stores printing data related to printing, moving speed data of the conveyor belt 21, etc. The printing data includes information of a printing pattern such as text or a mark.

[0079] The control unit 83 is a computer such as a central processing unit (CPU) or a microcontroller unit (MCU), and controls each unit. For example, the control unit 83 controls the supply unit 10 or the conveying unit 20, the detection unit 30, the first camera unit 40, the printing unit 50, the second camera unit 60, the recovery unit 70, the image processing unit 81, the storage unit 82, the maintenance unit 90, the cleaning unit 100, etc. based on various information or various programs stored in the storage unit 82. In addition, the control unit 83 receives a detection signal sent from the detection unit 30 or the position detector 25.

[0080] For example, the control unit 83 obtains the position of the tablet T in the X direction on the conveyor 21 based on the detection information sent from the detection unit 30, that is, the timing of detecting the tablet T on the conveyor 21, and sets the first imaging timing of the first imaging unit 40, the printing start timing of the inkjet head 51 of the printing unit 50, and the second imaging timing of the second imaging unit 60 based on the position information indicating the position of the tablet T in the X direction, and generates timing information indicating these timings and stores them in the storage unit 82. The so-called printing start timing refers to the timing of starting printing for the tablet T that has reached the printing position directly below the inkjet head 51. In addition, the control unit 83 can obtain information such as the movement amount (rotation amount) or speed of the conveyor 21 based on the detection information sent from the position detector 25.

[0081] In addition, the control unit 83 sets printing conditions for the tablet T having the position information based on the position information in the X direction, Y direction, and θ direction of the tablet T sent from the image processing unit 81. For example, the control unit 83 determines the range of the nozzles 51a used in the printing of the target tablet T in the inkjet head 51, that is, the nozzle range, based on the position information in the Y direction of the tablet T or the printing data, and sets printing conditions including the nozzle range or the printing start timing. In addition, in the case where the tablet T is a directional shape, the control unit 83 sets the printing conditions corresponding to the position of the tablet T in the θ direction based on the position information in the θ direction of the tablet T. As an example, the control unit 83 registers 180 printing patterns obtained by rotating the orientation of the printing pattern by one degree each time within the range of 0 degrees to 179 degrees in the storage unit 82, and selects a printing pattern with an angle suitable for the position of the tablet T in the θ direction from these printing patterns to set the printing conditions.

[0082] In addition, the control unit 83 determines whether the printed pattern is printed at a predetermined position of 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 81. For example, when determining the shape and size of the printed pattern, the control unit 83 registers the inspection printed pattern in the storage unit 82, and compares the inspection printed pattern with the printed pattern on the actual printed tablet T (printed pattern printed on the tablet T). After the comparison, the counter 84 described later counts the number of tablets T that have become "defective", and the control unit 83 calculates the ratio of good products to the total number of printed tablets (referred to as "good product rate"), and determines whether the good product rate is lower than a predetermined good product rate (for example, 99%) (the control unit functions as a calculation unit). Furthermore, the control unit 83 controls the timing of maintenance of the inkjet head 51 by a maintenance unit 90 described later, the timing of cleaning by the cleaning unit 100 , and the timing of movement of the inkjet head 51 .

[0083] In addition, the control unit 83 is suitable for storing various information (for example, position information or timing information, printing conditions, printing quality information, etc.) in the storage unit 82, but when the target tablet T is recovered by the recovery unit 70, for example, at a time point after a predetermined time (for example, several seconds) has passed since the tablet T fell from the downstream end of the conveying direction H1 in the conveying unit 20, the various information is deleted from the storage unit 82. However, when such information is needed in a subsequent process, etc., the various information of each tablet T may be retained without being deleted.

[0084] The counter 84 counts the total number of tablets T (the number of tablets detected by the detection unit 30) or the number of defective tablets. The counter 84 also counts the number of times maintenance is performed by the maintenance unit 90 described later.

[0085] (Printing process)

[0086] Next, refer to Figures 1 to 3 The printing process performed by the tablet printing device 1 will be described. The printing process also includes an inspection process. In addition, various information such as data required for printing is stored in the storage unit 82 in advance.

[0087] When the tablet printing device 1 starts printing, the motor 24 is driven, and the conveyor belt 21 rotates in the conveying direction H1 along with the rotation of the driving pulley 22 and the driven pulley 23 caused by the motor 24. In the state where the conveyor belt 21 rotates in the conveying direction H1, the tablets T are sequentially supplied from the hopper 11 to the chute 12, and are supplied from the chute 12 to the arrangement feeder 13. The tablets T are arranged in a row by the arrangement feeder 13, and are randomly supplied to the conveyor belt 21 rather than at regular intervals via the delivery feeder 14. The tablets T supplied to the conveyor belt 21 are transported at a predetermined moving speed while being arranged in a row on the conveyor belt 21.

[0088] The tablets T on the conveyor belt 21 are detected by the detection unit 30. Specifically, the timing when the tablet T on the conveyor belt 21 reaches the detection position (e.g., the laser light irradiation position) directly below the detection unit 30 is detected by the detection unit 30, and the position of the tablet T in the X direction on the conveyor belt 21 is recognized by the control unit 83 based on the timing when the tablet T is detected. Then, the position information indicating the position of the tablet T in the X direction is generated by the control unit 83 and stored in the storage unit 82.

[0089] Next, the first camera unit 40 photographs the tablet T on the conveyor belt 21. Specifically, the tablet T on the conveyor belt 21 is photographed by the first camera unit 40 at the first photographing timing when the tablet T reaches the photographing position directly below the first camera unit 40, and the first image obtained by the photographing by the first camera unit 40 is sent to the control device 80. Based on the first image, the position information of the tablet T in the X direction, Y direction, and θ direction is generated by the image processing unit 81, and stored in the storage unit 82. Based on the position information of the tablet T in the X direction, Y direction, and θ direction or information such as the printing pattern, the printing conditions including the nozzle range to be used or the printing start timing are set in the storage unit 82. In addition, based on the printing start timing (the timing to start printing on the tablet T), the ejection timing for the tablet T (the timing to eject ink on the tablet T) is determined.

[0090] Based on the printing conditions, the printing unit 50 performs printing. That is, the control unit 83 controls the inkjet head 51 of the printing unit 50 to print a specified printing pattern on the tablet T on the conveyor belt 21. In detail, at the printing start timing when the tablet T on the conveyor belt 21 passing under the first camera unit 40 reaches the printing position directly below the inkjet head 51, the inkjet head 51 performs printing based on the printing conditions. In the inkjet head 51, ink is appropriately ejected from each nozzle 51a to print a printing pattern (for example, numbers, letters, katakana, symbols, graphics) on the upper surface of the tablet T, i.e., the printed surface. The ink applied to the tablet T dries naturally during the conveyance process. In addition, a drying unit (not shown) that uses gas or heat for drying may also be provided, and the drying of the ink is supplemented by the drying unit.

[0091] Thereafter, the second imaging unit 60 captures the printed tablet T on the conveyor belt 21. Specifically, the second imaging unit 60 captures the printed tablet T on the conveyor belt 21 at a second imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 60, and the second image captured by the second imaging unit 60 is sent to the control device 80.

[0092] The second image is processed by the image processing unit 81 of the control device 80. Specifically, the image processing unit 81 acquires information related to the printed pattern printed on the tablet T, that is, the printing position, shape, and size of the printed pattern. The image processing unit 81 processes the second image sent from the second imaging unit 60, generates inspection information indicating the printing position, shape, and size of the printed pattern printed on the tablet T, and stores the information in the storage unit 82.

[0093] Based on the inspection information, the control unit 83 performs a printing state inspection. Specifically, based on the inspection information related to the printing position, shape, and size stored in the storage unit 82, the control unit 83 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 82. For example, in the printing state inspection, the printing pattern used in printing is stored in the storage unit 82 as a printing pattern for inspection, and the quality information related to the specified 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 82 to determine whether the printing pattern is normally printed on the tablet T (qualified or unqualified).

[0094] Finally, the tablets T on the conveyor belt 21 are recovered by the recovery unit 70. Specifically, when the tablets T after inspection are located at the end of the downstream side of the conveyor belt 21 as the conveyor belt 21 moves, they are released from the state of being held on the conveyor belt 21, fall from the conveyor belt 21, and are recovered by the recovery unit 70. At this time, the tablets T that are qualified and good products fall directly and are recovered by the recovery unit 70, but the tablets T that are unqualified and defective products are separated from the qualified products by air blowing in the middle of falling from the conveyor belt 21 and are recovered by the recovery unit 70.

[0095] (Maintenance process and inkjet head moving process)

[0096] Next, use Figure 4 The maintenance process of the inkjet head 51 and the conveying unit 20 (conveyor belt 21) and the moving process of the inkjet head 51 are described. In order to understand the maintenance process and the inkjet head moving process, a part of the description is repeated with the printing process.

[0097] As described above, when the printing process starts, the tablets supplied to the conveyor belt 21 are printed by the inkjet head 51 (S1). The printed tablets T are photographed by the second camera unit 60 (S2). Based on the image photographed by the second camera unit 60, the control unit 83 determines whether the printing on the tablet T is good or defective (S3), and calculates the yield rate, and reflects it in the yield rate if it is a defective product (S4). The control unit 83 determines whether the yield rate is lower than a specified value (for example, 99%) (S5). When the yield rate is lower than 99% (Y of S5), the maintenance unit 90 performs maintenance on the inkjet head 51 (S6). At the same time, the cleaning unit 100 cleans the conveyor unit 20 (conveyor belt 21) (S6). At this time, the vibrator (not shown) of the slide 12 is disconnected to stop the vibration, and the rotation direction of the arrangement feeder 13 is switched from A1 to the opposite direction (A2) within a specified time (e.g., 10 seconds). As a result, the tablets T supplied to the arrangement feeder 13 are not supplied to the transfer feeder 14 but flow back, and the backflowing tablets T are temporarily recovered in the box 130. Thereafter, the rotation of the arrangement feeder 13 is stopped. In this way, no new tablets T are supplied to the conveyor belt 21. For the tablets T that have been placed on the conveyor belt 21 at this point in time, they are not printed but conveyed and recovered to the recovery unit 70. When the maintenance of the inkjet head 51 by the maintenance unit 90 and the cleaning of the conveyor belt 21 by the cleaning unit 100 are completed, the control unit 83 determines whether the maintenance and cleaning are performed more than a specified number of times (for example, three times) (S7). When the maintenance and cleaning are performed for the first time (N of S7), the exciter of the slide 12 is turned on, and the arrangement feeder 13 is rotated again to supply tablets T to the conveyor belt 21, and the printing process is restarted. When the maintenance number of maintenance performed by the maintenance unit 90 is, for example, the fourth time (Y of S7), after the fourth maintenance performed by the maintenance unit 90 is completed, the nozzle range used is changed by moving the inkjet head 51 in a specified direction by a specified distance (S8). When the movement of the inkjet head 51 is completed, the supply of tablets T is restarted and the printing of tablets T is restarted (S9). When the maintenance process and the inkjet head movement process are completed in this way, and the printing of a predetermined number of tablets T is completed (Y of S10), the printing process is terminated. In addition, the tablets T temporarily stored in the box 130 may be put into the hopper 11 again later.

[0098] Here, as described above, the cleaning unit 100 cleans the conveying unit 20 (conveyor belt 21) by moving the brush 102 to a cleaning position in contact with the conveyor belt 21. The brush 102 of the cleaning unit 100 brushes off the tablet powder attached to the conveyor belt 21 by rubbing against the conveyor belt 21. The tablet powder attached to the conveyor belt 21 falls to a certain extent due to gravity, but because the conveyor belt 21 is charged, the tablet powder accumulates in an attached state, and the tablets placed thereon sometimes shake and cannot be stably sucked and held. In this way, if the inkjet head 51 is used for printing in a state where the tablets are not stably sucked and held, the position of the text printed on the tablets may deviate or bleed, although there is no problem with the inkjet head 51.

[0099] In addition, as described above, the maintenance of the inkjet head 51 by the maintenance unit 90 is performed by moving the maintenance unit 90 to a position (maintenance position) directly below the nozzle 51a of the inkjet head 51. It is known that the nozzle of the inkjet head may block part or all of the nozzle due to the drying of the ink present near the nozzle, resulting in poor ejection such as no ink ejection from the nozzle, bending of the ejection direction, and reduction in the amount of ejected ink. Most of these poor ejection are eliminated by maintenance performed by the maintenance unit 90 (the pressure delivery of the ink described above, or wiping with a scraper). However, if a specific nozzle 51a has reached its life due to a large number of uses, or the ink clogs the nozzle 51a to a degree that cannot be eliminated by maintenance, it is rare that the poor ejection cannot be eliminated even if maintenance is performed. In addition, the inkjet head 51 requires high precision in positioning. If the position of the inkjet head 51 deviates from the specified position, it will cause the printing position of the tablet T to deviate. Therefore, it is ideal to suppress the movement of the inkjet head to the minimum number of times.

[0100] Therefore, as in the present embodiment, first, by performing maintenance of the inkjet head 51 by the maintenance unit 90 and cleaning of the conveyor belt 21 by the cleaning unit 100 for a predetermined number of times, maintenance for eliminating the clogging of the nozzle 51a of the inkjet head 51, which may be the main cause of poor printing, and cleaning of the conveyor belt 21 are performed. Thus, the cause of poor printing in most cases can be eliminated. When the yield rate is still lower than the predetermined value, i.e., 99%, despite the maintenance performed by the maintenance unit 90 and the cleaning performed by the cleaning unit 100 for more than the predetermined number of times, i.e., three times, the inkjet head 51 is moved by the moving unit 52 to change the nozzle 51a used in printing, considering the possibility that the nozzle 51a of the inkjet head 51 has reached the end of its life.

[0101] Here, the moving distance of the inkjet head 51 is determined, for example, to be a position where the nozzle range before the movement does not overlap with the nozzle range after the movement (a position where the nozzle 51a used before the movement does not face the tablet T). Alternatively, when it is determined that the nozzle 51a in a certain area of ​​the inkjet head 51 has a poor ejection, the moving distance of the inkjet head 51 can be determined so as to avoid using the area. In addition, the moving direction can be Figure 1 The depth direction of the paper can also be the front direction of the paper.

[0102] In addition, a time limit may be set to count the number of maintenances performed by the maintenance unit 90. For example, if the time required from the time after the maintenance until the next time when the yield rate is lower than the prescribed value exceeds the prescribed time (e.g., 60 minutes), the cause of the defect generated when the previous yield rate is lower than the prescribed value is different from the cause of the defect generated when the next yield rate is lower than the prescribed value. Therefore, if the prescribed time, i.e., 60 minutes, has passed since the maintenance was performed once, the count of the counter 84 is reset to zero.

[0103] In addition, when tablets T are put into the device and printing starts, or when printing starts again after maintenance by the maintenance unit 90 and cleaning by the cleaning unit 100 are completed, a time of about 3 minutes is set before the yield rate is calculated, and the yield rate is not calculated during this period. The reason is to wait for the amount of printed tablets, which is a parameter for calculating the yield rate, to increase sufficiently so that the yield rate can be calculated correctly. Alternatively, it is also possible to set the maintenance action not to be performed even if the yield rate is lower than a specified value during this period.

[0104] As described above, according to the first embodiment, the number of times the inkjet head is moved can be minimized, and further, the malfunction of the tablet printing apparatus can be efficiently solved without stopping the entire apparatus to prevent a decrease in printing efficiency.

[0105] <Other embodiments>

[0106] In the above-described embodiment, the yield rate of tablets T is calculated based on the presence or absence of printing defects, but the present invention is not limited to this, and the yield rate may be calculated including appearance defects (cracks or defects of tablets, contamination, etc.).

[0107] In the above-described embodiment, it is illustrated that when the yield rate is lower than a specified value, the maintenance unit 90 performs maintenance on the inkjet head 51 and the cleaning unit 100 cleans the conveying unit 20, but it is not limited to this. Only maintenance by the maintenance unit 90 that has a high probability of helping to eliminate defects may be performed.

[0108] In the above-described embodiment, it is illustrated that when the yield rate is lower than a specified value, the vibration of the chute 12 is stopped and the rotation direction of the arrangement feeder 13 is reversed within a specified time and then stopped, so that no new tablets T are supplied to the conveyor belt 21, but it is not limited to this. For example, a gate may be provided at the exit of the chute 12, and the gate is closed to stop the supply of tablets T when the yield rate is lower than a specified value. Alternatively, the rotation direction of the arrangement feeder 13 may not be changed, and the supply of tablets T to the conveyor belt 21 may be stopped by disconnecting the adsorption of the position in the transfer feeder 14 that receives the tablets T from the arrangement feeder 13. At this time, the box 130 may also be provided on the downstream side of the arrangement feeder 13 ( Figure 1 The tablets on the arrangement feeder 13 are recovered below the arrangement feeder 13 (on the right side of the arrangement feeder 13).

[0109] In the above-described embodiment, the cleaning unit 100 is illustrated as being arranged below the suction chamber 26, but it is not limited to this. For example, it may also be arranged between a plurality of driven pulleys 23. It may be arranged anywhere as long as it is a place where the conveyor belt 21 can be cleaned, but by being arranged at a position where the tablets T are not carried (a position separated from the conveying path of the tablets T from the position where the tablets T are supplied from the transfer feeder 14 to the position where the tablets T are discharged to the recovery unit 70), it is prevented from hindering the conveying of the tablets T. In addition, the cleaning unit 100 is illustrated as having a rotatable brush 102, but it is not limited to this. For example, it may be a nozzle for sucking foreign matter such as powder of the tablets present on the conveyor belt 21, or it may be a nozzle for blowing away foreign matter on the conveyor belt 21 by blowing gas. Or it may be an elastic scraper for sweeping away foreign matter on the conveyor belt 21. Furthermore, it may be a wiping cloth or non-woven fabric moistened by infiltration of a volatile liquid or the like. Furthermore, a plurality of these may be combined and set.

[0110] In the above-described embodiment, the shape of the conveyor belt 21 is not particularly limited, but a conveyor belt having a texture pattern formed three-dimensionally on the surface may be used. The tablet printing device 1 sometimes includes a three-dimensional (3D) inspection unit (not shown) for inspecting the appearance of the tablet T, but when the conveyor belt 21 has a texture shape on the surface, the damage of the conveyor belt may be inspected by the 3D inspection unit.

[0111] In the above description, the tablets T are conveyed in one row, but the present invention is not limited thereto. The number of rows may be two or more, and there is no particular limitation. The number of conveyor belts 21 may be two or more, and there is no particular limitation. In addition, the number of inkjet heads 51 may be two or more, and there is no particular limitation.

[0112] In the above description, a print head having nozzles 51a arranged in one row is exemplified as the inkjet head 51, but the present invention is not limited thereto, and for example, a print head having nozzles 51a arranged in multiple rows may be used. In addition, multiple inkjet heads 51 may be arranged in a direction orthogonal to the conveying direction H1 in a horizontal plane and used.

[0113] In the above description, the tablets T are randomly supplied to the conveyor belt 21 instead of being supplied at regular intervals, but the present invention is not limited thereto and the tablets T may be supplied at regular intervals. In the above description, the tablets T are sucked and held by the suction holes formed on the conveyor belt 21, but the present invention is not limited thereto and the tablets T may be held in a pocket or the like for conveyance, or held on the conveyor belt 21 by their own weight for conveyance.

[0114] In addition, in the above description, printing on a single side of the tablet T is illustrated, but it is not limited to this. For example, the conveying section 20, the detection section 30, the first camera section 40, the printing section 50 and the second camera section 60 can also be used as a unit, and the units can be arranged to overlap each other up and down, and the printed tablet T can be flipped by the upper conveying section 20 and handed over to the lower conveying section 20, so that the tablet T can be printed on both sides.

[0115] Here, as the tablet T, tablets used for medical purposes, dietary purposes, cleaning purposes, industrial purposes or aromatic purposes may be included. In addition, as the tablet T, there are bare tablets (uncoated tablets) or sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multilayer tablets, core tablets, etc., and various capsule tablets such as hard capsules or soft capsules may also be included in the tablet T. Furthermore, as the shape of the tablet T, there are various shapes such as disc or lens, triangle, and ellipse. In addition, in the case where the tablet T as the printing object is for medical use or dietary use, the ink used is preferably edible ink. As the edible ink, any one of synthetic pigment ink, natural pigment ink, dye ink, and pigment ink can be used.

[0116] 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 ways, and various omissions, substitutions, and changes can be made without departing from the scope of 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.

Claims

1. A tablet printing device, characterized in that: include: The transport department transports tablets; an inkjet head that prints on the tablet conveyed by the conveying unit and has a plurality of nozzles; A maintenance unit for the inkjet head; a moving unit that moves the inkjet head in a direction orthogonal to a conveying direction in which the tablet is conveyed by the conveying unit; an imaging unit for imaging the tablet printed by the inkjet head; An image processing unit, which processes the image captured by the camera unit; a calculation unit that calculates a yield rate of the tablet based on the image processed by the image processing unit; a counter for counting the number of times the inkjet head is maintained by the maintenance unit; as well as The control unit determines whether the maintenance times counted by the counter exceed a prescribed times within a prescribed time. When the yield rate calculated by the calculation unit is lower than a predetermined value, the maintenance unit performs maintenance on the inkjet head. When the control unit determines that the maintenance frequency does not exceed the specified frequency within the specified time, the nozzles in the same range among the plurality of nozzles of the inkjet head are used for printing the tablet before and after the maintenance unit performs maintenance on the inkjet head. When the control unit determines that the maintenance frequency exceeds a specified number of times within a specified time, the moving unit is used to move the inkjet head so that the nozzles among the plurality of nozzles that are used for printing on the tablets before the movement of the inkjet head are not used for printing on the tablets after the movement of the inkjet head, and the nozzles of the inkjet head that are used for printing on the tablets are changed.

2. The tablet printing device according to claim 1, characterized in that: It also includes a cleaning unit for cleaning the conveying unit, The cleaning unit cleans the conveying unit at a timing when the maintenance unit performs maintenance on the inkjet head.

3. The tablet printing device according to claim 1 or 2, characterized in that: The calculation unit calculates a yield rate of the tablets including appearance defects based on the image.

4. A tablet printing method, characterized in that: include: A printing process, in which an inkjet head having a plurality of nozzles is used to print on the conveyed tablet; a photographing step of photographing the tablets printed in the printing step; a calculation step of calculating the yield rate of the tablet based on the image captured in the imaging step; A maintenance process, when the yield rate is lower than a specified value, maintaining the inkjet head; a counting step of counting the number of times the inkjet head is maintained by the maintenance step; A judging step of judging whether the number of maintenance times counted by the counting step exceeds a prescribed number of times within a prescribed time; as well as A moving process, in the judging process, if it is judged that the number of maintenance times of the inkjet head does not exceed the prescribed number of times within the prescribed time, before and after the maintenance of the inkjet head in the maintenance process, the nozzles in the same range among the plurality of nozzles of the inkjet head are used for printing the tablet, Furthermore, in the judgment process, if it is judged that the maintenance times of the inkjet head exceed the prescribed times within the prescribed time, the inkjet head is moved in a direction orthogonal to the conveying direction of the tablet, and the nozzles among the plurality of nozzles used for printing on the tablet before the movement of the inkjet head are not used for printing on the tablet after the movement of the inkjet head, and the nozzles of the inkjet head used for printing on the tablet are changed.

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