Tablet printing apparatus and tablet printing method

Abstract

We provide a printing device for tablets. [Solution] The tablet printing apparatus comprises a detection unit 22 that detects the height of tablets being transported by a conveyor belt 21a, imaging units 23 and 25 that image the tablets, an inkjet head 24 that ejects ink onto the tablets, a moving mechanism 26 that moves the conveyor belt or the inkjet head to change the distance between the nozzle surface and the conveyor belt, and a control unit 40 that controls each component. The detection unit detects the height information of the tablets on the conveyor belt, the control unit sets printability information for the inkjet head based on the height information, and controls the apparatus to print on tablets that are printable based on the printability information.

Description

Technical Field

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

Background Art

[0002] Currently, in order to print various information such as identification information on tablets, a tablet printing apparatus that performs printing using an inkjet head has been developed. In this tablet printing apparatus, the tablets are conveyed by a conveyor belt, and at this time, the tablets are held on the conveyor belt by suction or accommodation pockets or the like. Usually, the tablets are held in a lying state on the conveyor belt (for example, when the tablets are flat-shaped tablets, a state close to being flat), but may be held in a standing state (for example, when the tablets are flat-shaped tablets, a state close to being vertically upright). When a tablet in this standing state reaches directly below the inkjet head, it may collide with the inkjet head and cause damage, and the collided tablet may be damaged.

[0003] When a tablet collides with the inkjet head, the nozzles of the inkjet head may be damaged, and the inkjet head may become unusable. Also, when a tablet is damaged, a large amount of tablet powder may adhere to the nozzles of the inkjet head, and good ejection from the nozzles may not be possible. For this reason, the number of maintenance times of the inkjet head increases, or the maintenance time becomes longer. Due to such an increase in the number of maintenance times, an extension of the maintenance time, and the breakage of the tablets themselves, it is difficult to efficiently print on the tablets.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem that this invention aims to solve is to provide a tablet printing apparatus and a tablet printing method that can efficiently print on tablets. [Means for solving the problem]

[0006] A tablet printing apparatus according to an embodiment of the present invention comprises: a transport unit that transports tablets along the transport direction using a transport belt; a detection unit that detects tablets being transported by the transport belt; an imaging unit that images the tablets detected by the detection unit; an inkjet head that ejects ink onto the tablets detected by the detection unit; a moving mechanism that moves the transport belt or the inkjet head to change the distance between the nozzle surface of the inkjet head and the surface of the transport belt; and a control unit that controls the transport unit, the imaging unit, the inkjet head and the moving mechanism, wherein the detection unit detects height information of the tablets on the transport belt, and the control unit determines whether printing by the inkjet head is possible based on the height information. The control unit sets the printability information and controls the inkjet head to print on the tablets that are printable. The control unit further detects the arrival of the tablets when the height of the tablets exceeds a first predetermined threshold based on the height information, acquires position information of the tablets in the transport direction based on the timing when the tablets are detected, takes an image with the imaging unit at the timing based on the position information, sets the printability information to indicate whether the tablets are printable or not based on the image acquired by the imaging unit, and if it is determined that the height of the tablets exceeds a second predetermined threshold which is greater than the first predetermined threshold based on the height information, it sets the printability information to indicate that the tablets are not printable and controls the moving mechanism to widen the gap.

[0007] A tablet printing method according to an embodiment of the present invention includes: a transport unit transporting tablets by a transport belt; a detection unit detecting the tablets being transported by the transport belt; an imaging unit imaging the tablets detected by the detection unit; an inkjet head ejecting ink onto the tablets detected by the detection unit; a moving mechanism moving the transport belt or the inkjet head to change the distance between the nozzle surface of the inkjet head and the surface of the transport belt; and a control unit controlling the transport unit, the imaging unit, the inkjet head and the moving mechanism, wherein the detection unit detects height information of the tablets on the transport belt, and the control unit controls the inkjet head based on the height information. The control unit sets printability information, controls the inkjet head to print on tablets that are printable based on the printability information, and further detects the arrival of a tablet when the height of the tablet exceeds a first predetermined threshold based on the height information, acquires position information of the tablet in the transport direction based on the timing when the tablet is detected, takes an image with the imaging unit at the timing based on the position information, sets printability information indicating whether the tablet is printable or not based on the image acquired by the imaging unit, and if it is determined that the height of the tablet exceeds a second predetermined threshold which is greater than the first predetermined threshold based on the height information, sets printability information indicating that the tablet is not printable and controls the moving mechanism to widen the gap. [Effects of the Invention]

[0008] According to embodiments of the present invention, printing on tablets can be performed efficiently. [Brief explanation of the drawing]

[0009] [Figure 1] This is the first figure showing an example of a schematic configuration of a tablet printing apparatus according to the first embodiment. [Figure 2] This is a second figure showing an example of a schematic configuration of a tablet printing apparatus according to the first embodiment. [Figure 3]This figure shows an example of a schematic configuration of the control device according to the first embodiment. [Figure 4] This figure shows an example of a schematic configuration of the moving mechanism according to the first embodiment. [Figure 5] This is a flowchart showing an example of the printing process flow according to the first embodiment. [Figure 6] This figure shows an example of a schematic configuration of a tablet printing apparatus according to the second embodiment. [Modes for carrying out the invention]

[0010] <First Embodiment> The first embodiment will be described with reference to Figures 1 to 5.

[0011] (Example of tablet printing machine configuration) As shown in Figure 1, the tablet printing apparatus 1 according to the first embodiment comprises a supply device 10, a printing device 20, a collection device 30, and a control device 40.

[0012] The supply device 10 includes a hopper 11, an alignment feeder 12, and a transfer feeder 13. This supply device 10 is positioned on one end of the printing device 20 and is configured to supply tablets T, which are the objects to be printed, to the printing device 20. The hopper 11 holds a large number of tablets T and sequentially supplies the stored tablets T to the alignment feeder 12. The alignment feeder 12 aligns the supplied tablets T in a single line and transports them toward the transfer feeder 13 in the transport direction A1 (clockwise). The transfer feeder 13 sequentially sucks up and holds each tablet T lined up on the alignment feeder 12 from above, and transports each held tablet T in a single line to the printing device 20 and hands them over to the printing device 20. For the alignment feeder 12, for example, a belt transport mechanism or a vibrating feeder can be used. For the transfer feeder 13, for example, a belt transport mechanism can be used. The belt transport mechanism of this transfer feeder 13 rotates in the transport direction A2 (counterclockwise). The supply device 10 is electrically connected to the control device 40, and its operation is controlled by the control device 40.

[0013] The printing apparatus 20 includes a transport unit 21, a detection unit 22, a first imaging unit 23, an inkjet head 24, a second imaging unit 25, a moving mechanism 26, and a drying unit 27.

[0014] The conveying unit 21 includes a conveying belt 21a, a drive pulley 21b, a plurality of driven pulleys 21c, a motor 21d, a position detector 21e, and a suction chamber 21f. The conveying belt 21a is an endless belt and is stretched between the drive pulley 21b and each of the driven pulleys 21c. The drive pulley 21b and each of the driven pulleys 21c are rotatably mounted on the main body of the device (not shown), and the drive pulley 21b is connected to the motor 21d. The motor 21d is electrically connected to a control device 40, and its drive is controlled by the control device 40. The position detector 21e is a device such as an encoder and is attached to the motor 21d. This position detector 21e is electrically connected to the control device 40 and transmits a detection signal to the control device 40. The conveying unit 21 moves the conveying belt 21a along with each driven pulley 21c by the rotation of the drive pulley 21b by the motor 21d, and conveys the tablets T on the conveying belt 21a in the conveying direction A1 (clockwise direction).

[0015] As shown in Figure 2, the conveyor belt 21a has multiple circular suction holes 21g formed therein. Each of these suction holes 21g is a through-hole that attracts a tablet T, and they are arranged in a line along the conveying direction A1 to form a single conveying path. Each suction hole 21g is connected to the suction chamber 21f (see Figure 1) via a suction path (not shown) formed in the suction chamber 21f, and suction force can be obtained from the suction chamber 21f. A pump is connected to the suction chamber 21f via a suction tube (neither shown), and the inside of the suction chamber 21f is depressurized by the operation of the pump. The suction tube is connected to approximately the center of the side surface of the suction chamber 21f (the surface parallel to the conveying direction A1). The pump is also electrically connected to a control device 40, and its drive is controlled by the control device 40. When the inside of the suction chamber 21f is depressurized, tablets T placed on each suction hole 21g of the conveyor belt 21a are attracted by the suction holes 21g and held on the conveyor belt 21a.

[0016] The detection unit 22 is positioned downstream in the transport direction A1 from the location where the supply device 10 is installed, and is located above the transport path formed by the suction hole 21g. This detection unit 22 detects the position of the tablet T that has reached the detection position directly below the detection unit 22 (arrival of tablet T), i.e., the position of the tablet T on the transport belt 21a in the X direction (see Figure 2), by transmitting and receiving laser light. The detection unit 22 also detects the height of the tablet T on the transport belt 21a. For example, a displacement sensor can be used as the detection unit 22. Various types of laser sensors, such as reflective laser sensors, can be used as the displacement sensor. The detection unit 22 is electrically connected to the control device 40 and transmits a detection signal to the control device 40.

[0017] The first imaging unit 23 is positioned downstream in the transport direction A1 from the position where the detection unit 22 is located, and is provided above the transport path formed by the suction hole 21g. Based on the position information of the tablet T in the X direction detected by the detection unit 22, the first imaging unit 23 takes an image at a first imaging timing when the tablet T reaches the imaging position directly below the first imaging unit 23, acquiring a first image including the top surface of the tablet T, and transmitting the acquired first image to the control device 40. The first image is used to detect the position of the tablet T in the X, Y, and θ directions (see Figure 2), and to detect the presence or absence of damage or foreign matter (e.g., cracks, chips, dirt, etc.) on the tablet T. Various cameras having image sensors such as CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor) can be used as the first imaging unit 23. The first imaging unit 23 is electrically connected to the control device 40, and its drive is controlled by the control device 40. Illumination for imaging is also provided as needed.

[0018] Here, the positions of the tablet T in the X and Y directions are, for example, the positions in the XY coordinate system with respect to the center (reference position) of the imaging region of the first imaging unit 23. Also, the position in the θ direction is, for example, the position indicating the degree of rotation of the tablet T in the horizontal plane along the XY plane of the imaging region of the first imaging unit 23. This position in the θ direction is detected when the tablet T has a directional shape, such as when a score line is provided on the tablet T or when the tablet T is molded into an elliptical, oval, rectangular, or other shape. Note that the X and Y directions are positions in the horizontal direction.

[0019] The inkjet head 24 is positioned on the downstream side in the conveyance direction A1 from the position where the first imaging unit 23 is provided, and is provided above the conveyance path formed by the suction holes 21g. The inkjet head 24 has a plurality (for example, several hundred to several thousand) of nozzles 24a (see FIG. 2), and is provided such that the direction in which the nozzles 24a are arranged in a row (nozzle row) is orthogonal (an example of intersection) to the conveyance direction A1 in the horizontal plane. The inkjet head 24 individually ejects ink from each nozzle 24a by the operation of a drive element for each nozzle 24a. As this inkjet head 24, various inkjet printing heads having drive elements such as piezoelectric elements, heating elements, or magnetostrictive elements are used. The inkjet head 24 is electrically connected to the control device 40, and its driving is controlled by the control device 40.

[0020] The second imaging unit 25 is positioned downstream of the position where the inkjet head 24 is provided in the conveyance direction A1, and is provided above the conveyance path formed by the suction holes 21g. Based on the position information in the X direction of the tablet T detected by the detection unit 22, the second imaging unit 25 performs imaging at the second imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 25, acquires a second image including the upper surface of the tablet T, and transmits the acquired second image to the control device 40. The second image is used to inspect the printed pattern printed on the tablet T. As the second imaging unit 25, similar to the aforementioned first imaging unit 23, for example, various cameras having imaging elements such as CCDs and CMOSs are used. The second imaging unit 25 is electrically connected to the control device 40, and its driving is controlled by the control device 40. Illumination for imaging is provided as necessary.

[0021] The moving mechanism 26 moves the inkjet head 24 in the lifting direction (vertical direction in FIG. 1). This moving mechanism 26 is provided at a position adjacent to the conveyor belt 21a and the suction chamber 21f, avoiding the conveyor belt 21a and the suction chamber 21f (the back side of the paper in FIG. 1, the upper side in FIG. 2), and holds the inkjet head 24 facing the conveyance surface of the conveyor belt 21a. The conveyance surface of the conveyor belt 21a is the surface on which the tablet T is placed on the conveyor belt 21a, and is the surface of the conveyor belt 21a on the inkjet head 24 side. The moving mechanism 26 can change the distance (separation distance) between the conveyance surface of the conveyor belt 21a and the ejection surface of the inkjet head 24 by moving the inkjet head 24 up and down. The ejection surface of the inkjet head 24 is the surface on which the nozzles 24a are formed in the inkjet head 24, and is the surface of the inkjet head 24 on the conveyor belt 21a side. As the moving mechanism 26, for example, a linear guide mechanism is used. The moving mechanism 26 is electrically connected to the control device 40, and its driving is controlled by the control device 40.

[0022] The drying unit 27 is positioned opposite the conveyor belt 21a, for example, below the conveyor unit 21. This drying unit 27 dries the ink applied to each tablet T on the conveyor belt 21a. Various types of dryers can be used for the drying unit 27, such as a blower that dries using a gas such as air, a heater that dries using radiant heat, or a blower that dries using warm air or hot air by using both gas and a heater. The drying unit 27 is electrically connected to the control device 40, and its drive is controlled by the control device 40.

[0023] The recovery device 30 is positioned downstream in the transport direction A1 from the location where the drying unit 27 is provided, and is located below the transport unit 21. This recovery device 30 has a reusable product recovery unit 31, a defective product recovery unit 32, and a good product recovery unit 33. The recovery device 30 recovers reusable tablets T by the reusable product recovery unit 31, defective tablets T by the defective product recovery unit 32, and good tablets T by the good product recovery unit 33. For example, reusable products are tablets that can be reused, are undamaged and free of foreign matter, and are non-printed tablets. Defective products include non-printed tablets with foreign matter attached, and undamaged tablets free of foreign matter that are unsuitable for printing (printed tablets), while good products are undamaged tablets free of foreign matter that are suitable for printing (printed tablets). Note that the order in which the reusable product recovery unit 31, the defective product recovery unit 32, and the good product recovery unit 33 are arranged in the transport direction A1 is not limited to the order shown in Figure 1, and may be changed as appropriate. The recovery device 30 is electrically connected to the control device 40, and its operation is controlled by the control device 40.

[0024] The reusable product collection unit 31 has a spray nozzle 31a and a collection box 31b. The defective product collection unit 32 has a spray nozzle 32a and a collection box 32b. The good product collection unit 33 has a spray nozzle 33a and a collection box 33b. These spray nozzles 31a, 32a, and 33a have basically the same structure, and the collection boxes 31b, 32b, and 33b also have basically the same structure. For this reason, the spray nozzle 31a and the collection box 31b will be described as representative examples.

[0025] The spray nozzle 31a and the collection box 31b are positioned opposite each other across the conveying path where the suction holes 21g of the conveying belt 21a are lined up. The spray nozzle 31a is located inside the suction chamber 21f and, for example, sprays gas (e.g., air) toward the conveying belt 21a, causing the tablets T to fall from the conveying belt 21a. At this time, the gas sprayed from the spray nozzle 31a passes through the suction holes 21g of the conveying belt 21a and hits the tablets T. The spray nozzle 31a is electrically connected to the control device 40, and its drive is controlled by the control device 40. The collection box 31b is located directly below the spray nozzle 31a and below the conveying section 21. This collection box 31b receives and stores the tablets T that have fallen from the conveying belt 21a due to the gas sprayed from the spray nozzle 31a.

[0026] Here, the tablets T that have passed through the recycled product collection section 31 and the defective product collection section 32 are transported along with the movement of the conveyor belt 21a and reach a position near the end of the conveyor belt 21a on the side of each driven pulley 21c. At this position, the suction action on the tablets T ceases, but gas is blown onto the tablets T from above by the spray nozzle 33a, causing the tablets T to fall from the conveyor belt 21a. Therefore, by providing the spray nozzle 33a, the tablets T can be reliably dropped from the conveyor belt 21a. The collection box 33b receives and stores the tablets T that have fallen from the conveyor belt 21a due to the gas sprayed from the spray nozzle 33a.

[0027] The control device 40 controls various parts of the tablet printing apparatus 1, such as the supply device 10, the printing device 20, and the collection device 30, based on various information and programs. The control device 40 also receives detection information (e.g., detection signals) transmitted from the position detector 21e and detection unit 22 of the transport unit 21, and receives image information transmitted from the first imaging unit 23 and the second imaging unit 25. The control device 40 is implemented, for example, by an electronic circuit such as an integrated circuit or a computer.

[0028] (Example of control device configuration) Next, an example of the configuration of the control device 40 will be described with reference to Figure 3.

[0029] As shown in Figure 3, the control device 40 includes an image processing unit 41, a storage unit 42, and a control unit 43. An input device 40a and an output device 40b are connected to this control device 40. The input device 40a can be implemented by, for example, a switch, a touch panel, a keyboard, or a mouse. The output device 40b can be implemented by, for example, a display, a lamp, or a meter.

[0030] The image processing unit 41 takes in the first image captured by the first imaging unit 23 and the second image captured by the second imaging unit 25, and processes the images using known image processing techniques. For example, the image processing unit 41 processes the first image obtained from the first imaging unit 23 to obtain whether or not there is damage or foreign matter attached to the tablet T, and further obtains the position of the tablet T in the X, Y, and θ directions. The image processing unit 41 also processes the second image obtained from the second imaging unit 25 to obtain the printing position, shape, and size of the printing pattern (e.g., characters or marks) printed on the tablet T. The image processing unit 41 transmits the acquired information on whether or not there is damage or foreign matter attached to the tablet T, the acquired position information in the X, Y, and θ directions of each tablet T, and the printing position information, shape information, and size information of the printing pattern on each tablet T to the control unit 43.

[0031] The memory unit 42 stores processing information and various programs. For example, it is implemented by semiconductor memory elements such as RAM (Random Access Memory) and flash memory, or by storage devices such as hard disks and optical discs. The memory unit 42 stores printing data related to printing, data on the movement speed of the transport belt 21a, and so on. The printing data includes information on printing patterns such as characters and marks.

[0032] The control unit 43 is a computer, such as a CPU (Central Processing Unit), MCU (Micro Control Unit), or MPU (Micro Processing Unit), and controls each part. For example, the control unit 43 controls the supply device 10, printing device 20, retrieval device 30, image processing unit 41, and storage unit 42 based on various information and programs stored in the storage unit 42. The control unit 43 also receives detection signals transmitted from the position detector 21e and detection unit 22 of the transport unit 21, respectively. The control unit 43 can be implemented using either hardware and / or software.

[0033] For example, the control unit 43 determines whether the height of the tablet T on the conveyor belt 21a is abnormal based on height information regarding the height of the tablet T detected by the detection unit 22. For example, the control unit 43 determines that the height of the tablet T on the conveyor belt 21a is abnormal if the height of the tablet T exceeds a predetermined threshold. A tablet T with an abnormal height (hereinafter also referred to as a "height abnormal tablet") is, for example, a tablet in an upright position. A tablet T in an upright position is in a state where the posture of the tablet T is perpendicular or inclined to the conveying surface of the conveyor belt 21a, and if it is conveyed by the conveyor belt 21a toward directly below the inkjet head 24 in that posture, it will collide with the inkjet head 24, whose ejection surface is located at a predetermined normal position H1 (see Figure 4). The tablet T may be held on the conveyor belt 21a in an upright position by the suction action of the suction hole 21g. In particular, if the surface of the tablet T to be held has an R shape, one point other than the center of the tablet T may become the area that is suctioned, and the tablet may be held in an upright position.

[0034] Furthermore, the control unit 43 changes the transport speed at which the transport belt 21a transports the tablets T, and also changes the distance between the transport surface of the transport belt 21a and the ejection surface of the inkjet head 24, based on whether the height of the tablets T on the transport belt 21a is abnormal. For example, if the height of the tablets T on the transport belt 21a is abnormal, the control unit 43 controls the transport unit 21 to reduce the transport speed of the transport belt 21a and controls the moving mechanism 26 to widen the distance between the transport surface of the transport belt 21a and the ejection surface of the inkjet head 24. Subsequently, when the tablet T with the abnormal height passes directly below the inkjet head 24, the control unit 43 controls the moving mechanism 26 to return the inkjet head 24 to its normal position H1 and controls the transport unit 21 to return the transport speed of the transport belt 21a to its original value.

[0035] More specifically, as shown in Figure 4, the control unit 43 controls the movement mechanism 26 so that the inkjet head 24 rises and the ejection surface of the inkjet head 24 moves from a predetermined normal position H1 to a predetermined retracted position H2 when a tablet T is in an abnormal height state. This widens the gap between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24. Even if the tablet T in an abnormal height state reaches directly below the inkjet head 24, which has its ejection surface located at the predetermined retracted position H2, via the conveyor belt 21a in that state, it will pass directly below the inkjet head 24 without colliding with it. Subsequently, at the moment the tablet T in an abnormal height state passes directly below the inkjet head 24, the control unit 43 controls the movement mechanism 26 so that the inkjet head 24 descends and the ejection surface of the inkjet head 24 moves from the predetermined retracted position H2 to a predetermined normal position H1. This restores the gap between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24 to its original state.

[0036] Here, a predetermined threshold, a predetermined normal position H1, a predetermined retraction position H2, etc., are usually set in advance and stored, for example, in the storage unit 42. However, the predetermined threshold, predetermined normal position H1, predetermined retraction position H2, etc., may be changed according to predetermined conditions, or they may be changed according to the user's input operation to the input device 40a. The predetermined threshold is set to a value of the thickness of the tablet T + 1 mm. The distance between the printable surface of the tablet T and the ejection surface of the inkjet head 24 is usually about 1 mm, and the thickness of the tablet T is about 2 to 8 mm. Considering the case where the tablet T is 3 mm thick, when the detected height of the tablet T exceeds 4 mm, it will exceed the threshold and be determined to be a tablet T with an abnormal height, thus preventing the tablet T from colliding with the inkjet head 24. The predetermined normal position H1 is set by experimentally or theoretically determining a position (for example, a height 1 mm away from the print surface of the tablet T) where the inkjet head 24 does not collide with the tablet T in a lying position (normal orientation) on the transport belt 21a and where normal printing is possible on the tablet T on the transport belt 21a. The predetermined retracted position H2 is a position where the inkjet head 24 does not come into contact with the tablet T on the transport belt 21a where its height is abnormal (for example, a height greater than or equal to the major axis of the tablet T from the transport belt 21a). In both positions, appropriate margins are taken.

[0037] Furthermore, the control unit 43 acquires the position of the tablet T in the X direction on the conveyor belt 21a based on the detection information transmitted from the detection unit 22, i.e., the timing at which the tablet T on the conveyor belt 21a is detected. Based on this position information indicating the position of the tablet T in the X direction, the control unit 43 sets the first imaging timing of the first imaging unit 23, the printing start timing of the inkjet head 24, and the second imaging timing of the second imaging unit 25, and generates timing information indicating these timings and stores it in the storage unit 42. The printing start timing is the timing at which printing begins for the tablet T that has reached the printing position directly below the inkjet head 24. The control unit 43 can also acquire information such as the amount of movement (amount of rotation) and speed of the conveyor belt 21a based on the detection information transmitted from the position detector 21e.

[0038] Furthermore, the control unit 43 sets whether or not a tablet T is printable based on information transmitted from the image processing unit 41 regarding the presence or absence of damage or foreign matter (this information is based on the first image). Then, the control unit 43 sets the printing conditions as printing condition information for the tablet T for which the presence or absence information has been obtained. At this time, the control unit 43 sets the printing conditions for the tablet T for which the position information has been obtained based on the position information of the tablet T in the X, Y, and θ directions transmitted from the image processing unit 41. For example, the control unit 43 determines the range of nozzles 24a to be used to print the target tablet T in the inkjet head 24, i.e., the nozzle range to be used, based on the position information of the tablet T in the Y direction and the printing data, and sets the printing conditions including the nozzle range to be used and the printing start timing. If the tablet T has a directional shape, the control unit 43 sets the printing conditions corresponding to the position of the tablet T in the θ direction based on the position information of the tablet T in the θ direction. As an example, the control unit 43 stores 180 different print patterns in the storage unit 42, each obtained by rotating the orientation of the print pattern by 1 degree in the range of 0 to 179 degrees. From these print patterns, it selects a print pattern with an angle that matches the position of the tablet T in the θ direction and sets the print conditions.

[0039] Furthermore, the control unit 43 determines whether the print pattern has been printed in a predetermined shape and size at a predetermined location on the tablet T, that is, whether the print pattern has been successfully printed on the tablet T, based on the print position information, shape information, and size information of the print pattern printed on the tablet T transmitted from the image processing unit 41 (this information is based on the second image), and sets print quality information for the tablet T (print condition check). For example, in determining the shape and size of the print pattern, the control unit 43 registers a print pattern for inspection in the storage unit 42 and compares that print pattern for inspection with the actual print pattern on the tablet T after printing (the print pattern printed on the tablet T).

[0040] The control unit 43 stores various information (for example, information on whether the tablet T is damaged or has foreign matter attached, location information, height information, timing information, printability information, printing condition information, print quality information, etc.) in the storage unit 42 as appropriate. However, when the target tablet T is recovered by the recovery device 30, the various information is deleted from the storage unit 42 after a predetermined time (for example, a few seconds) has elapsed since it fell from the downstream end of the transport direction A1 in the transport unit 21. However, if this information is needed in subsequent processes, it is possible to leave the various information for each tablet T without deleting it, or to save it on storage media outside the device. When storing the various information for each tablet T, this information may be linked to the manufacturing date and lot number, etc., so that if defective tablets T are found after shipment, the cause can be traced back to investigate.

[0041] (Printing process) Next, the printing process performed by the aforementioned tablet printing apparatus 1 will be explained with reference to Figure 5. This printing process also includes an inspection process. Various information, such as the data required for printing and the data required for retracting the inkjet head 24, is stored in advance in the storage unit 42.

[0042] As shown in Figure 5, in step S1, when a large number of tablets T to be printed are loaded into the hopper 11 of the supply device 10, the tablets T are sequentially supplied from the hopper 11 to the alignment feeder 12, where they are arranged in a line and moved. In this example, the moving tablets T are sequentially supplied to the conveyor belt 21a of the printing device 20 by the transfer feeder 13. The conveyor belt 21a is rotated in the conveying direction A1 by the rotation of the drive pulley 21b and each driven pulley 21c by the motor 21d. As a result, the tablets T supplied onto the conveyor belt 21a are arranged in a line on the conveyor belt 21a and transported at a predetermined conveying speed.

[0043] In step S2, the tablet T on the conveyor belt 21a is detected by the detection unit 22. Specifically, the tablet T on the conveyor belt 21a is detected by the detection unit 22 when it reaches a detection position directly below the detection unit 22 (for example, the laser beam irradiation position), and based on the timing of the detection of the tablet T, the position of the tablet T in the X direction on the conveyor belt 21a is recognized by the control unit 43. Then, position information indicating the position of the tablet T in the X direction is generated by the control unit 43 and stored in the storage unit 42. In addition, the height of the tablet T on the conveyor belt 21a is detected by the detection unit 22, and height information relating to the height of the tablet T is recognized by the control unit 43 and stored in the storage unit 42.

[0044] In step S3, it is determined whether the height of the tablet T on the conveyor belt 21a is abnormal based on the height information. For example, it is determined whether the height of the tablet T on the conveyor belt 21a exceeds a predetermined threshold. If it is determined that the height of the tablet T on the conveyor belt 21a exceeds the predetermined threshold, it is determined that the height of the tablet T on the conveyor belt 21a is abnormal (Yes in step S3), and the process proceeds to step S11. On the other hand, if it is determined that the height of the tablet T on the conveyor belt 21a does not exceed the predetermined threshold, it is determined that the height of the tablet T on the conveyor belt 21a is normal (No in step S3), and the process proceeds to step S4.

[0045] In step S4, the tablet T on the conveyor belt 21a is imaged by the first imaging unit 23. Specifically, the tablet T on the conveyor belt 21a is imaged by the first imaging unit 23 at a first imaging timing when it reaches the imaging position directly below the first imaging unit 23, and the first image obtained by the imaging by the first imaging unit 23 is transmitted to the control device 40. Based on this first image, information on whether or not the tablet T is damaged or has foreign matter attached, as well as position information of the tablet T in the X, Y, and θ directions, is generated by the image processing unit 41 and stored in the storage unit 42.

[0046] In step S5, the control unit 43 determines whether printing is possible on the target tablet T based on information regarding damage to the tablet T and the presence or absence of foreign matter. If it is determined that printing is possible on the target tablet T (Yes in step S5), the process proceeds to step S6. Based on information such as the position information of the tablet T in the X, Y, and θ directions and the printing pattern, printing conditions, including the nozzle range to be used and the printing start timing for the tablet T set as printable (printable tablet T), are set in the storage unit 42. Based on the aforementioned printing start timing (the timing at which printing begins on the tablet T), the ejection timing for the tablet T (the timing at which ink is ejected to the tablet T) is determined. On the other hand, if it is determined that printing is not possible on the target tablet T (No in step S5), the process proceeds to step S9, and operations related to printing and inspection of the target tablet T are restricted. The printability information of the tablet T is stored in the storage unit 42 as appropriate. Note that "restriction" of operations related to printing and inspection means that at least the printing and inspection processes for the target tablet T are not performed.

[0047] In step S6, printing is performed by the inkjet head 24 based on the above printing conditions. That is, the control unit 43 controls the inkjet head 24 to print a predetermined printing pattern on the printable tablets T on the transport belt 21a. Specifically, the printable tablets T on the transport belt 21a that have passed below the first imaging unit 23 are printed by the inkjet head 24 based on the aforementioned printing conditions at the printing start timing when they reach the printing position directly below the inkjet head 24. The inkjet head 24 ejects ink appropriately from each nozzle 24a and prints a printing pattern (for example, numbers, alphabets, katakana, symbols, figures) on the printable surface, which is the upper surface of the tablet T.

[0048] In step S7, the printed tablet T on the conveyor belt 21a is imaged by the second imaging unit 25. Specifically, the printed tablet T on the conveyor belt 21a is imaged by the second imaging unit 25 at a second imaging timing when it reaches the imaging position directly below the second imaging unit 25, and the second image obtained by the imaging by the second imaging unit 25 is transmitted to the control device 40. This second image is processed by the image processing unit 41 of the control device 40. Specifically, information regarding the printed pattern printed on the tablet T, that is, the printing position, shape, and size of the printed pattern, is acquired by the image processing unit 41. The second image transmitted from the second imaging unit 25 is processed by the image processing unit 41, and inspection information indicating the printing position, shape, and size of the printed pattern on the tablet T is generated and stored in the storage unit 42.

[0049] In step S8, the control unit 43 performs a print condition inspection based on the inspection information described above. Specifically, based on the inspection information related to the print position, shape, and size stored in the storage unit 42, the control unit 43 determines whether the print pattern has been successfully printed on the tablet T, and print quality information indicating the print quality of the tablet T is generated and stored in the storage unit 42. For example, in the print condition inspection, the print pattern used for printing is stored in the storage unit 42 as an inspection print pattern, and good product information regarding the predetermined print position, shape, and size of the inspection print pattern is compared with the inspection information regarding the print position, shape, and size of the actual printed print pattern stored in the storage unit 42 to determine whether the print pattern has been successfully printed on the tablet T (pass or fail).

[0050] In step S9, the tablets T on the conveyor belt 21a are collected by the collection device 30. The ink applied to the tablets T dries naturally during conveyance and is also dried by the drying unit 27. Specifically, when a reusable tablet T reaches the reusable product collection unit 31 as it moves along the conveyor belt 21a, gas is blown onto the tablet T from above by the spray nozzle 31a, causing the tablet T to fall from the conveyor belt 21a and be collected in the collection box 31b. Similarly, when a defective tablet T reaches the defective product collection unit 32 as it moves along the conveyor belt 21a, gas is blown onto the tablet T from above by the spray nozzle 32a, causing the tablet T to fall from the conveyor belt 21a and be collected in the collection box 32b. Furthermore, when a good tablet T reaches a position near the end of the conveyor belt 21a on the side of each driven pulley 21c, the suction effect on the tablet T ceases, and gas is blown onto the tablet T from above by the spray nozzle 33a. The tablet T then falls from the conveyor belt 21a and is collected by the collection box 32b. This control of gas blowing is performed by the control unit 43 based on various information such as the position information of the tablet T, the height information of the tablet T, printability information, and print quality information.

[0051] In step S10, the control unit 43 determines whether printing is complete or not. For example, the number of printed tablets T is counted, and when that number reaches a predetermined production quantity, it is determined that printing is complete. If it is determined that printing is complete (Yes in step S10), the process ends. On the other hand, if it is determined that printing is not complete (No in step S10), the process returns to step S1. Regarding the determination of printing completion, it may also be determined in response to user input operations to the input device 40a, for example, when the user presses the print completion button.

[0052] In step S3 described above, if it is determined that the height of the tablet T on the conveyor belt 21a is abnormal (Yes in step S3), then in step S11, the conveying speed of the conveyor belt 21a is reduced by the control unit 43. For example, the conveying speed may be gradually or in steps at a constant rate from a predetermined normal speed, or it may be gradually or in steps at a random rate. The predetermined normal speed is reduced to a predetermined speed, and it is desirable that this predetermined speed be a conveying speed of about 1 / 10 of the normal speed.

[0053] For example, a predetermined speed is determined based on the distance between the position directly below the detection unit 22 on the conveyor belt 21a and the position directly below the inkjet head 24, and the time required for the ejection surface of the inkjet head 24 to move from a predetermined normal position H1 to a predetermined retracted position H2. The distance between the position directly below the detection unit 22 on the conveyor belt 21a and the position directly below the inkjet head 24 is, for example, the distance between the detection position where the detection unit 22 detects the tablet T on the conveyor belt 21a and the position directly below the upstream end in the conveying direction A1 of the inkjet head 24.

[0054] In step S12, the inkjet head 24 is raised by the moving mechanism 26. For example, the inkjet head 24 is raised until its ejection surface moves from a predetermined normal position H1 to a predetermined retracted position H2 (see Figure 4). As a result, the distance between the transport surface of the transport belt 21a and the ejection surface of the inkjet head 24 widens to a predetermined retraction interval. This predetermined retraction interval is such that even if a tablet T in an abnormal height state reaches directly below the inkjet head 24 by the transport belt 21a in that state, it can pass directly below the inkjet head 24 without colliding with it.

[0055] In step S13, the control unit 43 restricts printing on multiple tablets T located before and after a tablet T that is in an abnormal height state, i.e., a tablet T with an abnormal height. For example, the inkjet head 24 is raised by the moving mechanism 26 and ejection is interrupted. As a result, the tablet T with an abnormal height and the tablets T transported before and after it (i.e., tablets T that pass directly below the inkjet head 24 when the inkjet head 24 is in the retracted position H2) are not printed by the inkjet head 24. As a result, the occurrence of defective tablets T (failed to print) can be suppressed.

[0056] In step S14, the control unit 43 determines whether or not the tablet T with an abnormal height has passed directly beneath the inkjet head 24. If it is determined that the tablet T with an abnormal height has passed directly beneath the inkjet head 24 (Yes in step S14), the process proceeds to step S15. For example, the control unit 43 determines that the tablet T with an abnormal height has passed directly beneath the inkjet head 24 if a predetermined time has elapsed since the detection unit 22 detected the tablet T on the transport belt 21a. Alternatively, whether or not the tablet T with an abnormal height has passed directly beneath the inkjet head 24 may also be determined by detection by the position detector 22e.

[0057] For example, the predetermined time is determined based on the transport speed of the tablet T (the changing transport speed), the distance between the position directly below the detection unit 22 and the position directly below the inkjet head 24 on the transport belt 21a, and the amount of movement (rotation) of the transport belt 21a. The distance between the position directly below the detection unit 22 and the position directly below the inkjet head 24 on the transport belt 21a is, for example, the distance between the detection position where the tablet T on the transport belt 21a is detected by the detection unit 22 and the position directly below the downstream end of the transport direction A1 of the inkjet head 24.

[0058] In step S15, the inkjet head 24 is lowered by the moving mechanism 26. For example, the inkjet head 24 is lowered until its ejection surface moves from a predetermined retracted position H2 to a predetermined normal position H1 (see Figure 4). As a result, the distance between the transport surface of the transport belt 21a and the ejection surface of the inkjet head 24 returns to a predetermined normal distance (the distance when the inkjet head 24 is in the normal position H1).

[0059] In step S16, the conveying speed of the conveyor belt 21a is returned to its original value by the control unit 43, and the process proceeds to step S9. For example, the conveying speed may be gradually or stepwise increased at a constant rate up to a predetermined normal speed, or it may be gradually or stepwise increased at a random rate. The predetermined normal speed is set in advance and is stored, for example, in the storage unit 42. However, the predetermined normal speed may be changed according to predetermined conditions, or according to user input operations to the input device 40a.

[0060] In this printing process, the control unit 43 reduces the transport speed of the transport belt 21a in response to the detection of an abnormal height by the detection unit 22, and further increases the gap between the side of the inkjet head 24 facing the transport belt 21a and the side of the transport belt 21a facing the inkjet head 24. As a result, tablets T with abnormal heights on the transport belt 21a can pass through without colliding with the inkjet head 24. Therefore, damage to the inkjet head 24 and breakage of tablets T can be suppressed, thereby reducing adverse effects such as increased maintenance frequency, extended maintenance time, and breakage of tablets T, and enabling efficient printing on tablets T.

[0061] Furthermore, in response to the detection of an abnormal height, the control unit 43 may reduce the transport speed of the transport belt 21a and continue printing by the inkjet head 24 until just before the tablet T with the abnormal height reaches directly below the inkjet head 24. In other words, the inkjet head 24 remains in the normal position H1 and continues printing until it prints on the tablet T located one position downstream (in the transport direction A1) of the tablet T with the abnormal height. From the time the tablet T with the abnormal height is detected until the tablet T located one position downstream of the tablet T with the abnormal height reaches directly below the inkjet head 24, the transport speed of the transport belt 21a is reduced to a speed that allows the inkjet head 24 to move from the normal position H1 to the retracted position H2 in the time it takes for the transport belt 21a to move by the distance between the tablets being transported on the transport belt 21a. The control unit 43 corrects the ejection timing of the inkjet head 24 to match the transport speed of the transport belt 21a during this period and continues printing on the tablets T.

[0062] The control unit 43 raises the inkjet head 24, and as soon as the tablet T with an abnormal height passes directly beneath the inkjet head 24, it returns the inkjet head 24 to its original height position (normal position H1), returns the transport speed of the transport belt 21a to the normal speed, and resumes printing at the normal transport speed. Printing by the inkjet head 24 is interrupted only during the raising of the inkjet head 24, the passing of the tablet T with an abnormal height below the inkjet head 24, and the lowering of the inkjet head 24. Printing is performed when the inkjet head 24 is in the normal position H1, so that printing on the tablets T can be performed efficiently. In other words, tablets following the tablet T with an abnormal height that are located at a distance equal to the length of the transport direction A1 of the inkjet head 24 cannot be printed on, but printing can be resumed after the tablet T with an abnormal height has passed the downstream end in the transport direction A1 of the inkjet head 24, thus minimizing the number of tablets T that become unprinted due to the transport of the tablet T with an abnormal height. Furthermore, the printing and inspection processes for subsequent tablets T following the height-abnormal tablet T will also be restricted, and these tablets T will also become unprinted tablets.

[0063] Here, the supply speed at which tablets T are supplied from the supply device 10 to the transport unit 21 (the transport speed at which feeders such as the alignment feeder 12 and the transfer feeder 13 transport tablets T) is usually set slower than the transport speed at which the transport belt 21a transports tablets T. For this reason, the control unit 43 may reduce the supply speed of the supply device 10 when it reduces the transport speed of the transport belt 21a in order to maintain a predetermined speed difference between the supply speed of the supply device 10 and the transport speed of the transport belt 21a. This makes it possible to prevent tablets T from getting stuck in feeders such as the alignment feeder 12 and the transfer feeder 13.

[0064] Furthermore, the control unit 43 may control the supply device 10 to stop supplying new tablets T as soon as it detects a tablet T with an abnormal height. This prevents new tablets T from being supplied onto the conveyor belt 21a in response to the occurrence of a tablet T with an abnormal height. The maintenance mechanism (not shown) for the inkjet head 24 moves between the inkjet head 24 and the conveyor belt 21a to perform maintenance. At this time, the inkjet head 24 may retract to a position higher than its normal position H1 to create space for the maintenance mechanism. Therefore, once the tablets T on the conveyor belt 21a are collected and no new tablets T are supplied to the conveyor belt 21a, maintenance work on the inkjet head 24 can be performed. Alternatively, maintenance of the conveyor belt 21a (and suction holes 21g) may be performed at the same time as maintenance of the inkjet head 24.

[0065] Furthermore, the control unit 43 may restrict the ink ejection from the inkjet head 24 for tablets T that pass directly under the detection unit 22 during the period when the transport speed of the transport belt 21a is reduced, and control the recovery device 30 to recover tablets T that pass directly under the detection unit 22 during the period when the transport speed of the transport belt 21a is reduced as reusable unprinted tablets, i.e., reusable products. This makes it possible to recover tablets T that pass directly under the detection unit 22 during the period when the transport speed of the transport belt 21a is reduced as reusable products.

[0066] Furthermore, the inkjet head 24 is moved by the moving mechanism 26 to change the distance between the mounting surface of the conveyor belt 21a and the ejection surface of the inkjet head 24, but this is not limited to this; for example, the conveyor belt 21a may be moved by the moving mechanism 26. This movement of the conveyor belt 21a may be achieved by moving the entire conveying unit 21 by the moving mechanism 26, or by moving a part of the conveyor belt 21a facing the inkjet head 24 by the moving mechanism 26.

[0067] In this case, when the object being transported is a tablet T, for example, the speed at which it passes under the inkjet head 24 is orders of magnitude faster compared to when the object being transported is paper. Furthermore, the relative size difference between the object being transported and the inkjet head 24 is large, and the transport interval between each object is narrow. Therefore, it is not enough to simply prevent collisions between the object being transported and the inkjet head 24; it is important to devise a way to prevent collisions while simultaneously reducing the number of tablets T that are affected, such as those that cannot be printed, by retracting the inkjet head 24 to prevent collisions. Also, if the operation of the entire device is stopped due to the detection of a tablet T with an abnormal height, and the tablets T on the transport belt 21a are collected without being printed (unprinted tablets), productivity will be significantly reduced. Therefore, according to the embodiment described above, it is possible to solve the tablet-specific problems that do not exist in paper printing. Note that when printing on tablets T, unlike when printing on paper, one inkjet head 24 may be used to print on multiple tablets T arranged horizontally and perpendicularly to the transport direction.

[0068] As described above, according to the first embodiment, the tablet printing apparatus 1 includes a transport unit 21 that transports tablets T by a transport belt 21a, a detection unit 22 that detects tablets T being transported by the transport belt 21a, an inkjet head 24 that ejects ink to the tablets T detected by the detection unit 22, a moving mechanism 26 that moves the transport belt 21a or the inkjet head 24 to change the distance between the surface of the inkjet head 24 on the transport belt 21a side and the surface of the transport belt 21a on the inkjet head 24 side, and a control unit 43 that controls the transport unit 21 and the moving mechanism 26. The detection unit 22 detects height information of the tablets T on the transport belt 21a, and the control unit 43, based on the height information, controls the transport unit 21 to reduce the transport speed of the transport belt 21a and controls the moving mechanism 26 to widen the distance if the height of the tablets T exceeds a predetermined threshold. As a result, when the height of the tablet T exceeds a predetermined threshold, the transport speed of the transport belt 21a is reduced, and the gap between the transport belt 21a side of the inkjet head 24 and the inkjet head 24 side of the transport belt 21a is widened. This prevents tablets T with abnormal heights on the transport belt 21a from colliding with the inkjet head 24. Therefore, damage to the inkjet head 24 and breakage of tablets T can be suppressed, reducing adverse effects such as increased maintenance frequency, extended maintenance time, and tablet T breakage, and enabling efficient printing on tablets T.

[0069] <Second Embodiment> A second embodiment will be described with reference to Figure 6.

[0070] As shown in Figure 6, the tablet printing apparatus 2 according to the second embodiment is capable of printing on both sides of a tablet T, and includes a second printing apparatus 50 in addition to the supply apparatus 10, first printing apparatus 20, recovery apparatus 30, and control device 40 according to the first embodiment. Note that, unlike the first embodiment, the recovery apparatus 30 is provided for the second printing apparatus 50 rather than the first printing apparatus 20.

[0071] The first printing device 20 and the second printing device 50 are arranged stacked on top of each other. The tablets T printed by the upper first printing device 20 are inverted and passed to the lower second printing device 50, where both sides of the tablets T are printed. Normally, to ensure a smooth transfer of tablets T from the first printing device 20 to the second printing device 50, the transport speeds of the first printing device 20 and the second printing device 50 are always the same. Therefore, if the transport speed of one of them is changed by the control unit 43, the transport speed of the other device is also changed accordingly by the control unit 43.

[0072] The second printing apparatus 50 has the same structure as the first printing apparatus 20. Specifically, the second printing apparatus 50 comprises a transport unit 51, a detection unit 52, a first imaging unit 53, an inkjet head 54, a second imaging unit 55, a moving mechanism 56, and a drying unit 57. The transport unit 51 also includes a transport belt 51a, a drive pulley 51b, a plurality of driven pulleys 51c, a motor 51d, a position detector 51e, and a suction chamber 51f. This transport unit 51 transports the tablets T on the transport belt 51a in the transport direction A2 (counterclockwise direction). Note that each element constituting the second printing apparatus 50 has basically the same structure as each element constituting the first printing apparatus 20, so their explanation is omitted.

[0073] Here, when a tablet T with an abnormal height is transferred from the first printing device 20 to the second printing device 50, its state often remains unchanged, and it continues to be abnormally high on the conveyor belt 51a of the second printing device 50. However, in some cases, its state may change, for example, by lying flat on the conveyor belt 51a of the second printing device 50. For this reason, the following explanation will be divided into two cases: one in which the abnormal height of the tablet T is detected in both the first printing device 20 and the second printing device 50 (first and second processing examples), and another in which the abnormal height of the tablet T is detected only in the first printing device 20, and this detection result is also used in the second printing device 50 (third processing example).

[0074] (Example of processing in the first case) In the first processing example, when the detection unit 22 of the first printing device 20 detects an abnormal height of the tablet T on the conveyor belt 21a, the control unit 43 reduces the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50, and continues printing by the inkjet head 24 of the first printing device 20 until just before the tablet T in the abnormal height state reaches directly below the inkjet head 24 of the first printing device 20. The control unit 43 raises the inkjet head 24 of the first printing device 20 to the retracted position H2, and as soon as the tablet T in the abnormal height state passes directly below the inkjet head 24, the inkjet head 24 is returned to the normal position H1, the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50 are returned to the normal speed, and printing is resumed. This processing flow is the same as steps S11 to S16 shown in Figure 5. During the rise of the inkjet head 24, the passage of the abnormally sized tablet T below the inkjet head 24, and the descent of the inkjet head 24, printing by the inkjet head 54 of the second printing device 50 continues. Therefore, printing on the tablet T can be performed efficiently. Although printing on the abnormally sized tablet T is restricted in the first printing device 20, this restriction on printing on the tablet T continues in the second printing device 50 as well.

[0075] Similarly, when the detection unit 52 of the second printing device 50 detects an abnormal height of the tablet T on the conveyor belt 51a, the control unit 43 reduces the conveying speed of the conveyor belts 21a and 51a and continues printing with the inkjet head 54 of the second printing device 50 until just before the tablet T with the abnormal height reaches directly below the inkjet head 54. The control unit 43 raises the inkjet head 54 of the second printing device 50 to the retracted position H2, and as soon as the tablet T with the abnormal height passes directly below the inkjet head 54, the control unit 43 returns the inkjet head 54 to the normal position H1, returns the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50 to the normal speed, and resumes printing. This process flow is the same as steps S11 to S16 shown in Figure 5. During the rise of the inkjet head 54, the passage of the abnormally sized tablet T below the inkjet head 54, and the descent of the inkjet head 54, printing by the inkjet head 24 of the first printing device 20 continues. Therefore, printing on the tablet T can be performed efficiently.

[0076] The specific processing flow for this first processing example is as shown in Figure 5, where step S1 is executed, steps S2-S8 and S11-S16 are executed in the first printing device 20, then steps S2-S8 and S11-S16 are executed in the second printing device 50, and then steps S9-S10 are executed. In other words, in the first processing example, both the first printing device 20 and the second printing device 50 detect whether or not there is an abnormality in the height of the tablet T, and perform the same processing as in the first embodiment. As mentioned above, printing on multiple tablets T, including tablets T with an abnormal height (i.e., tablets T that pass directly below the inkjet heads 24 and 54 when the inkjet heads 24 and 54 are in the retracted position H2), is restricted in the first printing device 20, and this restriction on printing on tablets T continues in the second printing device 50. This is also the case in the second and third processing examples described below.

[0077] According to this first processing example, in the first printing device 20 and the second printing device 50, damage to each inkjet head 24, 54 and damage to the tablets T can be suppressed, thereby reducing adverse effects such as increased maintenance frequency, extended maintenance time, and damage to the tablets T, and enabling efficient printing on the tablets T. Furthermore, printing by inkjet head 24 is interrupted only during the rise of inkjet head 24, the passage of tablets T with abnormal height below inkjet head 24, and the descent of inkjet head 24. Similarly, printing by inkjet head 54 is interrupted only during the rise of inkjet head 54, the passage of tablets T with abnormal height below inkjet head 54, and the descent of inkjet head 54. When inkjet head 24 or inkjet head 54 is in the normal position H1, printing is performed by either head, thus enabling efficient printing on the tablets T.

[0078] (Second example of processing) The difference between the second processing example and the first processing example is that when the first printing device 20 detects a tablet T with an abnormal height, it reduces the transport speed of the transport belts 21a and 51a, and then maintains the reduced transport speed of the transport belts 21a and 51a until the tablet T with an abnormal height passes below the inkjet head 54.

[0079] In the first processing example, the speed at which a tablet T with an abnormal height is transferred from the first printing device 20 to the second printing device 50 is the normal speed, which may result in the tablet T not being transferred properly. For example, the normal speed is the fastest possible speed that allows a tablet T lying flat to be transferred from the first printing device 20 to the second printing device 50 without changing its state. Therefore, if the transfer of a tablet T with an abnormal height is performed at the normal speed, the transfer may be improper and fail. Specifically, the tablet T may fall from the conveyor belt 21a or conveyor belt 51a, resulting in the tablet T that should have been collected in the recycled product collection unit 31 being mixed in with another collection device, or falling to the bottom of the tablet printing device 2 and being damaged. Therefore, a second processing example will be described in which, when the detection unit 22 of the first printing device 20 detects an abnormal height of the tablet T on the conveyor belt 21a, both the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50 are kept lowered, thereby reducing the speed at which the tablet T is transferred from the first printing device 20 to the second printing device 50.

[0080] In the second processing example, when the detection unit 22 of the first printing device 20 detects an abnormal height of the tablet T on the conveyor belt 21a, the control unit 43 reduces the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50, and continues printing by the inkjet head 24 of the first printing device 20 until just before the tablet T in the abnormal height state reaches directly below the inkjet head 24 of the first printing device 20. The control unit 43 raises the inkjet head 24 of the first printing device 20, and as soon as the tablet T in the abnormal height state passes directly below the inkjet head 24, it returns the inkjet head 24 to its original height position and resumes printing. During the raising of the inkjet head 24, the passing of the tablet T with the abnormal height below the inkjet head 24, and the lowering of the inkjet head 24, printing by the inkjet head 54 of the second printing device 50 continues. Therefore, printing on the tablet T can be performed efficiently.

[0081] Subsequently, when the detection unit 52 of the second printing device 50 detects an abnormal height of the tablet T on the conveyor belt 51a, the conveying speed of each conveyor belt 21a and 51a is maintained at a low speed, and the control unit 43 continues printing with the inkjet head 54 of the second printing device 50 until just before the tablet T with the abnormal height reaches directly below the inkjet head 54. The control unit 43 raises the inkjet head 54 of the second printing device 50, and as soon as the tablet T with the abnormal height passes directly below the inkjet head 54, it returns the inkjet head 54 to its original height position, returns the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50 to normal speed, and resumes printing. During the raising of the inkjet head 54, the passing of the tablet T with the abnormal height below the inkjet head 54, and the lowering of the inkjet head 54, printing by the inkjet head 24 of the first printing device 20 continues. Therefore, printing on the tablet T can be performed efficiently.

[0082] On the other hand, if the detection unit 52 of the second printing device 50 does not detect any abnormality in the height of the tablets T on the conveyor belt 21a, the control unit 43 returns the conveying speed of the conveyor belt 21a of the first printing device 20 and the conveying speed of the conveyor belt 51a of the second printing device 50 to normal speed. Furthermore, for tablets T that could not be printed by the inkjet head 24 of the first printing device 20, printing will not be performed by the inkjet head 54 of the second printing device 50 either, and these unprinted tablets, for example, recycled tablets T, will be collected by the recycled product collection unit 31.

[0083] Furthermore, if the detection unit 22 of the first printing device 20 does not detect a height abnormality, but the detection unit 52 of the second printing device 50 does, the control unit 43 reduces the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50, and continues printing by the inkjet head 54 of the second printing device 50 until just before the tablet T, which is in an abnormal height state, reaches directly below the inkjet head 54 of the second printing device 50. The control unit 43 raises the inkjet head 54 of the second printing device 50, and as soon as the tablet T, which is in an abnormal height state, passes directly below the inkjet head 54, the control unit 43 returns the inkjet head 54 to its original height position, returns the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50 to normal speed, and resumes printing by the inkjet head 54. During the rise of the inkjet head 54, the passage of the abnormally sized tablet T below the inkjet head 54, and the descent of the inkjet head 54, printing by the inkjet head 24 of the first printing device 20 continues. Therefore, printing on the tablet T can be performed efficiently.

[0084] This second processing example can achieve the same effect as the first processing example. Furthermore, while the tablet T, whose height abnormality has been detected by the detection unit 22 of the first printing device 20, is being transferred from the first printing device 20 to the second printing device 50, the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50 are kept reduced. This makes it possible to reduce the speed at which the tablet T is transferred from the first printing device 20 to the second printing device 50. With the transport speed reduced during the transfer, one end of the tablet T with the height abnormality, located downstream in the transport direction A1, is pushed by the first printing device 20, and the other end is gradually transferred to the second printing device 50. This increases the likelihood that the posture of the tablet T with the height abnormality can be returned to its normal posture when transferred from the first printing device 20 to the second printing device 50, compared to transfer at the normal transport speed, and enables smooth transfer of the tablet T.

[0085] (Third processing example) Here, it is assumed that tablets T that are abnormally tall in the first printing device 20 will often remain abnormally tall even after being transferred to the second printing device 50. In this case, the detection unit 52 of the second printing device 50 may be set not to detect the height of the tablets T. In such a case, the height of the tablets T is detected only by the first printing device 20, and processing is performed on both the first printing device 20 and the second printing device 50 according to the height detection. A third example of processing in which the height of the tablets T is detected only by the first printing device 20 will be described.

[0086] In the third processing example, when the detection unit 22 of the first printing device 20 detects an abnormal height, the control unit 43 reduces the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50, and continues printing by the inkjet head 24 of the first printing device 20 until just before the tablet T, which is in an abnormal height state, reaches directly below the inkjet head 24 of the first printing device 20. The control unit 43 raises the inkjet head 24 of the first printing device 20, and as soon as the tablet T, which is in an abnormal height state, passes directly below the inkjet head 24, it returns the inkjet head 24 to its original height position and resumes printing. During the raising of the inkjet head 24, the passing of the tablet T with the abnormal height below the inkjet head 24, and the lowering of the inkjet head 24, printing by the inkjet head 54 of the second printing device 50 continues. Therefore, printing on the tablet T can be performed efficiently.

[0087] Here, a tablet T that is abnormally tall in the first printing device 20 is treated as a tablet with an abnormal height in the second printing device 50. However, in reality, its condition may change when it is transferred from the first printing device 20 to the second printing device 50. Therefore, on the conveyor belt 51a of the second printing device 50, it becomes a tablet whose height is unknown, i.e., a tablet with an unknown height.

[0088] The control unit 43 continues printing by the inkjet head 54 of the first printing device 50 until the tablet T, which is in an abnormal height state, is transferred from the first printing device 20 to the second printing device 50 and reaches just before it reaches directly below the inkjet head 54 of the second printing device 50. The control unit 43 raises the inkjet head 54 of the second printing device 50, and as soon as the tablet T in the abnormal height state passes directly below the inkjet head 54, it returns the inkjet head 54 to its original height position, returns the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50 to normal speed, and resumes printing. During the raising of the inkjet head 54, the passing of the tablet T with the abnormal height state below the inkjet head 54, and the lowering of the inkjet head 54, printing by the inkjet head 24 of the first printing device 20 continues. Therefore, printing on the tablet T can be performed efficiently.

[0089] This third processing example can achieve the same effect as the first processing example. Furthermore, when a tablet T with an abnormal height is detected by the detection unit 22 of the first printing device 20 is transferred from the first printing device 20 to the second printing device 50, the transport speed of the transport belt 21a of the first printing device 20 and the transport speed of the transport belt 51a of the second printing device 50 are kept reduced until the tablet T has passed at least directly under the inkjet head 54 of the second printing device 50. This makes it possible to reduce the speed at which the tablet T is transferred from the first printing device 20 to the second printing device 50, thus increasing the likelihood that the posture of the tablet T with an abnormal height can be returned to its normal posture, similar to the second processing example, and enabling a smooth transfer of the tablet T from the first printing device 20 to the second printing device 50.

[0090] As explained above, the second embodiment provides the same effects as the first embodiment. In other words, even when double-sided printing is performed on the tablet T as in the second embodiment, printing on the tablet T can be performed just as efficiently as when single-sided printing is performed on the tablet T as in the first embodiment.

[0091] <Other Embodiments> In the above description, printing is performed on tablets T using tablet printing devices 1 and 2 (tablet printing method) according to one embodiment of the invention. This can also be rephrased as "printing is performed on tablets T using tablet printing devices 1 and 2 (tablet printing method) according to one embodiment of the invention, and printed tablets T are manufactured." In other words, tablet printing devices 1 and 2 can be replaced with tablet manufacturing devices, and tablet printing method can be replaced with tablet manufacturing method.

[0092] Furthermore, although the above explanation uses the example of transporting tablets T in a single line, it is not limited to this, and the number of lines may be two or more, and the number of transport belts 21a may also be two or more, and is not limited. Also, the number of inkjet heads 24 and 54 may also be two or more, and is not limited.

[0093] Furthermore, in the above explanation, the inkjet head 24 was exemplified as a print head in which nozzles 24a are arranged in a single row, but it is not limited to this, and for example, a print head in which nozzles 24a are arranged in multiple rows may be used. Alternatively, multiple inkjet heads 24 may be arranged in a direction perpendicular to the transport direction A1 in the horizontal plane. The same applies to the inkjet head 54.

[0094] Furthermore, in the above explanation, it was given as an example that the inkjet head 24 is arranged such that the direction in which the nozzles 24a are aligned is perpendicular to the transport direction A1 in the horizontal plane. However, it is not limited to this, and for example, the nozzles 24a may be arranged so that the direction in which they are aligned intersects the transport direction A1 in the horizontal plane. The same applies to the inkjet head 54.

[0095] Furthermore, although the above description states that the tablets T are supplied randomly rather than at regular intervals on the conveyor belt 21a, this is not limited to this, and they may be supplied at regular intervals. Also, although the above description states that the tablets T are held in place by suction holes 21g formed on the conveyor belt 21a, this is not limited to this, and they may be held and transported in pockets or the like, or they may be held and transported on the conveyor belt 21a by their own weight. The same applies to the conveyor belt 51a.

[0096] Furthermore, while the above description exemplified gradually or in stages reducing the transport speed of the transport belts 21a and 51a, the system is not limited to this. When the detection unit 22 detects that the height of the tablet T exceeds a predetermined threshold, the transport speed may be rapidly reduced to the target transport speed. When returning the transport speed of the transport belts 21a and 51a from the reduced speed back to the normal speed, it may be done gradually or in stages, or rapidly, similar to the reduction. In any case, gradually or in stages changing the transport speed helps prevent the tablet T from detaching from the transport belts 21a and 51a.

[0097] Furthermore, in the above description, the control unit 43 was given the example of determining whether the height of the tablet T is abnormal based on the height information of the tablet T detected by the detection units 22 and 52, but it is not limited to this. For example, height information may be obtained by detecting the area, length, and shape of the tablet T supplied to the transport belts 21a and 51a when viewed from above, based on the image of the tablet T obtained by the first imaging unit 23 (indirectly detecting the height of the tablet T). In other words, the height of the tablet T may be determined to be abnormal when the area or length of the tablet T when viewed from above falls below a threshold.

[0098] Furthermore, in the above description, the control unit 43 exemplified the instruction that, when a tablet T with an abnormal height is detected by the detection units 22 and 52, the inkjet heads 24 and 54 print until the inkjet heads 24 and 54 move to the retracted position H2, or up to the tablet T located one position upstream of the tablet T with an abnormal height. However, the control unit 43 is not limited to this. For example, printing by the inkjet head 24 may be interrupted when a tablet T with an abnormal height is detected by the detection units 22 and 52, and the inkjet head 24 may be moved from the normal position H1 to the retracted position H2. In this case, it is sufficient to reduce the transport speed of the transport belts 21a and 51a to a speed that allows the transport belts to move to the retracted position H2 between the detection of the tablet T with an abnormal height and the time it reaches the inkjet head 24 (54). Alternatively, the inkjet heads 24 and 54 may be controlled to move to the retracted position H2 so that the tablets T whose printing is restricted are a few tablets before and after the tablet T with an abnormal height (for example, about 10 tablets, or the time it is expected that about 10 tablets will be transported). In this case, the speed difference between the conveyor belts 21a and 51a before and after the reduction in conveying speed is small, and the number of prints per unit time can be increased.

[0099] Here, the aforementioned tablet T can include tablets used for pharmaceutical, edible, cleaning, industrial, or fragrance purposes. Furthermore, tablet T can include uncoated tablets, sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multilayer tablets, and core tablets, and various types of capsule tablets such as hard capsules and soft capsules can also be included in tablet T. In addition, tablet T can take various shapes such as disc-shaped, lens-shaped, triangular, and oval. Moreover, if the tablet T to be printed is for pharmaceutical or edible purposes, edible ink is preferable as the ink used. This edible ink can be any of synthetic dye ink, natural dye ink, dye ink, or pigment ink.

[0100] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0101] 1. Tablet printing machine 2. Tablet printing device 10 Feeding device 11 Hoppa 12 Alignment Feeders 13 Transfer Feeder 20 Printing device 21 Conveying section 21a Conveyor belt 21b Drive pulley 21c Driven Pulley 21d motor 21e Position detector 21f Suction Chamber 21g suction hole 22 Detection unit 23 First imaging unit 24 inkjet heads 24a Nozzle 25 Second imaging unit 26 Moving mechanism 27 Drying section 30 Recovery device 31. Recyclable Materials Collection Department 31a Spray nozzle 31b Collection box 32 Defective Product Collection Department 32a Spray nozzle 32b Collection Box 33. Good Product Collection Department 33b Collection Box 33a Spray nozzle 40 Control device 40a Input device 40b Output device 41 Image Processing Unit 42 Storage section 43 Control Unit 50 Printing device 51 Conveying section 51a Conveyor belt 51b Drive pulley 51c Driven pulley 51d motor 51e Position detector 51f Suction Chamber 52 Detection unit 53 First imaging unit 54 inkjet heads 55 Second imaging unit 56 Moving mechanism 57 Drying section A1 Conveying direction A2 Conveying direction H1 Normal position H2 Evacuation position T Tablets

Claims

1. A conveying unit that conveys tablets along the conveying direction using a conveyor belt, A detection unit for detecting tablets being transported by the aforementioned conveyor belt, An imaging unit for imaging the tablet detected by the detection unit, An inkjet head that ejects ink onto the tablet detected by the detection unit, A moving mechanism that moves the conveyor belt or the inkjet head so as to change the distance between the nozzle surface of the inkjet head and the surface of the conveyor belt, The transport unit, the imaging unit, the inkjet head, and the control unit that controls the moving mechanism, Equipped with, The detection unit detects the height information of the tablets on the conveyor belt, The control unit, Based on the height information, information on whether the inkjet head can print is set, and based on the printability information, the system controls the inkjet head to print on the tablets that are printable. The control unit further detects the arrival of the tablet when the height of the tablet exceeds a first predetermined threshold based on the height information, acquires position information of the tablet in the transport direction based on the timing when the tablet is detected, takes an image with the imaging unit at the timing based on the position information, and sets printability information, indicating whether it is printable or not, based on the image acquired by the imaging unit. If, based on the height information, it is determined that the height of the tablet exceeds a second predetermined threshold which is greater than the first predetermined threshold, the printability information is set to indicate that printing is not possible, and the moving mechanism is controlled to widen the spacing. Tablet printing machine.

2. The tablet printing apparatus according to claim 1, wherein the control unit controls the subsequent tablets of the tablet for which the printability information has been set to be unprintable, and which are located at a distance equal to the length of the inkjet head in the transport direction, so as to not print with the inkjet head.

3. The tablet printing apparatus according to claim 1, wherein the second predetermined threshold is greater than the thickness of the tablet and less than the distance from the conveyor belt to the nozzle surface of the inkjet head.

4. The tablet printing apparatus according to claim 1 or 2, wherein the control unit controls the transport unit to reduce the transport speed of the transport belt when the height of the tablet exceeds the second predetermined threshold.

5. The tablet printing apparatus according to claim 1 or 2, wherein the control unit controls the moving mechanism to return the gap to its original position when the height of the tablet exceeds the second predetermined threshold and the tablet passes directly below the inkjet head.

6. A collection box for collecting the tablets printed by the inkjet head from the conveyor belt, The device further includes a spray nozzle that blows gas into the collection box so that the tablets fall into it. The tablet printing apparatus according to claim 1 or 2, wherein the control unit controls the spray nozzle to spray the gas from the spray nozzle onto the tablet based on the position information, the height information, and the printability information.

7. The conveying unit conveys tablets using a conveyor belt, The detection unit detects the tablets being transported by the transport belt, The imaging unit captures the tablet detected by the detection unit, The inkjet head ejects ink onto the tablet detected by the detection unit, The moving mechanism moves the conveyor belt or the inkjet head so as to change the distance between the nozzle surface of the inkjet head and the surface of the conveyor belt, The control unit controls the transport unit, the imaging unit, the inkjet head, and the moving mechanism. Includes, The detection unit detects the height information of the tablets on the conveyor belt, The control unit, Based on the height information, information on whether the inkjet head can print is set, and based on the printability information, the system controls the inkjet head to print on the tablets that are printable. The control unit further detects the arrival of the tablet when the height of the tablet exceeds a first predetermined threshold based on the height information, acquires position information of the tablet in the transport direction based on the timing when the tablet is detected, takes an image with the imaging unit at the timing based on the position information, and sets printability information, indicating whether it is printable or not, based on the image acquired by the imaging unit. Based on the height information, if it is determined that the height of the tablet exceeds a second predetermined threshold which is greater than the first predetermined threshold, the printability information is set to indicate that printing is not possible, and the moving mechanism is controlled to widen the spacing. Tablet printing method.

Images