JP7651397B2 - Tablet printing device and tablet printing method - Google Patents

Description

Embodiments of the present invention relate to a tablet printing device and a tablet printing method.

A technology is known that uses an inkjet head to print identification information (an example of information) such as letters or marks on tablets. A tablet printing device that uses this technology transports tablets using a transport device such as a conveyor, and ejects ink from each nozzle of an inkjet head arranged above the transport device toward the tablets that pass under the inkjet head, thereby printing the identification information on the tablets.

However, in inkjet heads, for example in nozzles that are used infrequently, the ink around the nozzles can dry out over time, causing the nozzles to become clogged with hardened ink, resulting in problems (poor ejection) such as ink being ejected at an angle or not being ejected at all when used for printing.

When such a malfunction occurs, it is necessary to stop the transport of tablets, interrupt tablet printing, and perform maintenance on the inkjet head.

Japanese Unexamined Patent Publication No. 7-081050

The problem that this invention aims to solve is to provide a tablet printing device and tablet printing method that can perform printing efficiently even when an inkjet head has an ejection problem.

The tablet printing device according to the embodiment of the present invention includes a conveyor belt for conveying tablets, an imaging device for imaging the tablets conveyed by the conveyor belt, a print head device for printing on the tablets downstream of the imaging device in the conveying direction of the tablets conveyed by the conveyor belt, a print status confirmation device for confirming the print status of the tablets downstream of the print head device in the conveying direction, and a control unit for controlling the printing process by the print head device, and the control unit generates positional deviation information of the tablets based on the images captured by the imaging device and sets the printing conditions of the tablets based on the positional deviation information, the control unit identifies the position of the nozzle with a defective discharge in the print head device based on the results of the print status confirmation device, and when the printing conditions set based on the positional deviation information are printing conditions that use the nozzle with a defective discharge, the control unit controls the print head device to prohibit printing using the printing conditions.

The tablet printing method according to an embodiment of the present invention includes a step of conveying a tablet by a conveyor belt, an imaging step of imaging the tablet conveyed by the conveyor belt, a step of printing the tablet by a print head device downstream of the imaging step in the conveying direction of the tablet conveyed by the conveyor belt, and a print state confirmation step of confirming the print state of the tablet downstream of the print head device in the conveying direction, and is characterized in that the method generates positional deviation information of the tablet based on the image captured in the imaging step, sets printing conditions for the tablet based on the positional deviation information, identifies the position of a defective nozzle in the print head device based on the result of the print state confirmation step, and when the printing conditions set based on the positional deviation information are printing conditions that use the defective nozzle, prohibits printing by the print head device using the printing conditions, and when the printing conditions are printing conditions that do not use the defective nozzle, performs printing by the print head.

FIG. 1 is a diagram showing a tablet printing apparatus according to a first embodiment. FIG. 1 is a plan view illustrating a first printing apparatus according to a first embodiment. 10 is a flowchart showing when printing using a discharge-defective nozzle is prohibited in the first embodiment.

First Embodiment
The first embodiment will be described with reference to FIGS.

(Basic configuration)
As shown in Figure 1, a tablet printing device 1 according to one embodiment includes a supply device 10, a first printing device 20, a second printing device 30, a collection device 40, and a control device (control unit) 50.

The first printing device 20 and the second printing device 30 have basically the same structure. The components of the tablet printing device 1, the supply device 10, the first printing device 20, the second printing device 30, and the recovery device 40, are arranged in this order, and the tablets T are transported in this order while a series of processes of supply, printing, and recovery are performed. The path along which the tablets T are transported is called the transport path P. In other words, the upstream side of the transport path P is the supply device 10 side, and the downstream side is the recovery device 40 side. In this embodiment, two parallel rows of transport paths P are formed.

The supply device 10 has a hopper 11, an alignment feeder 12, and a transfer feeder 13. The supply device 10 is configured to be able to supply tablets T to be printed to the first printing device 20, and is positioned at one end side of the first printing device 20. The hopper 11 stores a large number of tablets T and sequentially supplies the tablets T to the alignment feeder 12. The alignment feeder 12 aligns the supplied tablets T in two rows and transports them toward the transfer feeder 13. The transfer feeder 13 sequentially sucks in and holds each tablet T arranged in two rows on the alignment feeder 12 from the upper side of the tablets T, transports each held tablet T in two rows to the first printing device 20, and delivers them to the first printing device 20. The supply device 10 is electrically connected to the control device 50, and its drive is controlled by the control device 50. For example, a belt conveying mechanism can be used as the alignment feeder 12 and the transfer feeder 13.

The first printing device 20 includes a conveying device (conveying section) 21, a detection device 22, a first imaging device (imaging device for printing) 23, a print head device (printing section) 24, a second imaging device (imaging device for inspection) 25, and a drying device 26.

The conveying device 21 has a conveying belt 21a, a driving pulley 21b, a plurality of (three in the example of FIG. 1) 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 over the driving pulley 21b and each driven pulley 21c. The driving pulley 21b and each driven pulley 21c are rotatably mounted on the device body, and the driving pulley 21b is connected to the motor 21d. The motor 21d is electrically connected to the control device 50, and its drive is controlled by the control device 50. 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 50 and transmits a detection signal to the control device 50. The control device 50 can obtain information such as the position, speed, and movement amount of the conveying belt 21a based on the detection signal. This conveying device 21 rotates the conveying belt 21a together with each driven pulley 21c by rotating the driving pulley 21b by the motor 21d, and conveys the tablets T on the conveying belt 21a in the conveying direction A1 (clockwise direction), which is the direction of the arrow A1 in Figure 1.

As shown in FIG. 2, a plurality of circular suction holes 21g are formed on the surface of the conveyor belt 21a. These suction holes 21g are through holes that adsorb the tablets T onto the surface of the conveyor belt 21a, and are arranged in two parallel rows along the conveying direction A1 to form two conveying paths P. Each suction hole 21g is connected to the inside of the suction chamber 21f through a suction path formed in the suction chamber 21f, and suction force can be obtained by the suction chamber 21f. An intake device such as a pump is connected to the suction chamber 21f through an intake pipe (not shown), and the inside of the suction chamber 21f is depressurized by the operation of the intake device. The intake pipe is connected to approximately the center of the side surface (parallel to the conveying direction A1) of the suction chamber 21f. The intake device is electrically connected to the control device 50, and its drive is controlled by the control device 50.

The detection device 22 has multiple detection units 22a (two in the example of FIG. 2). The detection units 22a are arranged one by one for each conveying path P downstream of the position where the tablets T are supplied to the conveying belt 21a by the supply device 10 in the conveying direction A1 and in a direction intersecting (for example, perpendicular to) the conveying direction A1 in a horizontal plane, and are provided above the conveying belt 21a. The detection units 22a detect the position of the tablets T on the conveying belt 21a (the position of the tablets T in the conveying direction A1) by projecting and receiving laser light, and function as trigger sensors for each device located downstream. Various types of laser sensors, such as reflective laser sensors, can be used as the detection units 22a. Each detection unit 22a is electrically connected to the control device 50 and transmits a detection signal to the control device 50.

The first imaging device 23 has a plurality of imaging units 23a (two in the example of FIG. 2). The imaging units 23a are arranged one by one for each conveying path P in a direction that crosses the conveying direction A1 in a horizontal plane (for example, a direction perpendicular to the conveying direction A1) downstream of the position where the detection device 22 is provided, and are provided above the conveying belt 21a. Based on the position information of the tablet T described above, the imaging unit 23a captures an image when the tablet T reaches directly below the imaging unit 23a, obtains an image including the upper surface of the tablet T (image for printing), and transmits the obtained image to the control device 50. As the imaging unit 23a, various cameras having imaging elements such as a CCD (charge-coupled device) or a CMOS (complementary metal-oxide semiconductor) can be used. Each imaging unit 23a is electrically connected to the control device 50, and the driving of each imaging unit 23a is controlled by the control device 50. In addition, illumination for imaging is also provided as necessary.

The print head device 24 has a plurality of inkjet print heads 24a (two in the example of FIG. 2). The print heads 24a are arranged downstream of the position where the first imaging device 23 is provided in the transport direction A1, in a direction intersecting (for example, perpendicular to) the transport direction A1 in a horizontal plane, one for each transport path P, and are provided above the transport belt 21a. The print head 24a has a plurality of nozzles 24b (eight in the example of FIG. 2, but in reality, several hundred to several thousand) and ejects ink from each of the nozzles 24b. The print head 24a is provided so that the alignment direction of the nozzles 24b intersects (for example, perpendicular to) the transport direction A1 in a horizontal plane. As the print head 24a, various inkjet print heads having driving elements such as piezoelectric elements, heating elements, or magnetostrictive elements can be used. Each print head 24a is electrically connected to the control device 50, and the driving of each of the print heads is controlled by the control device 50.

The second imaging device 25 has a plurality of imaging units 25a (two in the example of FIG. 2). The imaging units 25a are arranged one by one for each conveying path P in a direction that crosses the conveying direction A1 in a horizontal plane (for example, a direction perpendicular to the conveying direction A1) downstream of the position where the print head device 24 is provided, and are provided above the conveying belt 21a. Based on the position information of the tablet T described above, the imaging unit 25a captures an image when the tablet T reaches directly below the imaging unit 25a, obtains an image (image for inspection) including the upper surface of the tablet T, and transmits the obtained image to the control device 50. As with the imaging unit 23a described above, various cameras having imaging elements such as CCD and CMOS can be used as the imaging unit 25a. Each imaging unit 25a is electrically connected to the control device 50, and their driving is controlled by the control device 50. In addition, illumination for imaging is also provided as necessary.

Returning to FIG. 1, the drying device 26 is positioned downstream in the conveying direction A1 from the position where the print head device 24 is provided, and is provided, for example, below the conveying device 21. This drying device 26 is a drying device common to the two rows of conveying paths P, and dries the ink applied to each tablet T on the conveying belt 21a. As the drying device 26, various drying units can be used, such as a blower that dries using gas such as air, a heater that dries using radiant heat, or a blower that dries using warm or hot air by combining gas and a heater. The drying device 26 is electrically connected to the control device 50, and its drive is controlled by the control device 50.

The tablets T that have passed above the drying device 26 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 effect on the tablets T ceases, and the tablets T are released from the state held by the conveyor belt 21a and are transferred from the first printing device 20 to the second printing device 30.

The second printing device 30 includes a conveying device 31, a detection device 32, a first imaging device (imaging device for printing) 33, a print head device 34, a second imaging device (imaging device for inspection) 35, and a drying device 36. The conveying device 31 includes a conveying belt 31a, a driving pulley 31b, a plurality of (three in the example of FIG. 1) driven pulleys 31c, a motor 31d, a position detector 31e, and a suction chamber 31f. Note that each element constituting the second printing device 30 has a structure basically the same as that of the corresponding element of the first printing device 20 described above, and therefore the description thereof is omitted. The conveying direction of the second printing device 30 is the conveying direction A2 (counterclockwise direction) which is the direction of the arrow A2 in FIG. 1.

The recovery device 40 includes a defective product recovery device 41, a recyclable product recovery device 42, and a non-defective product recovery device 43. This recovery device 40 is provided downstream in the conveying direction A2 from the position where the drying device 36 of the second printing device 30 is provided. The recovery device 40 basically recovers defective tablets T using the defective product recovery device 41, recovers recyclable tablets T (described later) using the recyclable product recovery device 42, and recovers non-defective tablets T using the non-defective product recovery device 43.

The defective product collection device 41 has multiple injection nozzles 41a and a storage box (collection box) 41b. The injection nozzles 41a are provided for each transport path P, and the storage box 41b is provided in common to each transport path P.

The injection nozzles 41a are arranged in a direction intersecting (e.g., perpendicular to) the conveying direction A2 in the horizontal plane, one for each conveying path P, and are provided in the suction chamber 31f of the second printing device 30. The injection nozzles 41a, for example, inject gas (e.g., air) toward the conveying belt 31a, causing tablets T to fall from the conveying belt 31a. At this time, the gas injected from the injection nozzles 41a passes through the suction holes (similar to the suction holes 21g shown in FIG. 2) of the conveying belt 31a and hits the tablets T. The injection nozzles 41a are electrically connected to the control device 50, and their operation is controlled by the control device 50.

The storage boxes 41b are provided directly below each injection nozzle 41a and below the conveyor device 31. The storage boxes 41b receive and store tablets T that have fallen from the conveyor belt 31a due to the gas injected from the injection nozzles 41a.

The injection nozzle 41a may be installed in a position other than inside the suction chamber 31f of the second printing device 30. For example, the injection nozzle 41a may be installed below the conveying device 31, and gas may be injected toward the side of the tablet T being conveyed by the conveying belt 31a. In this case, the injection nozzle 41a may be installed at an angle to the vertical direction. In this case, the storage box 41b is installed taking into account the gas injection direction of the injection nozzle 41a.

The reusable item recovery device 42 has multiple spray nozzles 42a and a storage box (recovery box) 42b. The multiple spray nozzles 42a are provided for each transport path P, and the storage box 42b is provided in common to each transport path P.

The injection nozzles 42a are arranged in a direction intersecting (e.g., perpendicular to) the conveying direction A2 in the horizontal plane, one for each conveying path P, and are provided in the suction chamber 31f of the second printing device 30. The injection nozzles 42a, for example, inject gas (e.g., air) toward the conveying belt 31a, causing tablets T to fall from the conveying belt 31a. At this time, the gas injected from the injection nozzles 42a passes through the suction holes (similar to the suction holes 21g shown in FIG. 2) of the conveying belt 31a and hits the tablets T. The injection nozzles 42a are electrically connected to the control device 50, and their operation is controlled by the control device 50.

The storage boxes 42b are provided directly below each injection nozzle 42a and below the conveyor device 31. These storage boxes 42b receive and store tablets T that have fallen from the conveyor belt 31a due to the gas injected from the injection nozzles 42a.

The injection nozzle 42a may be installed in a position other than inside the suction chamber 31f of the second printing device 30. For example, the injection nozzle 42a may be installed below the conveying device 31, and gas may be injected toward the side of the tablet T being conveyed by the conveying belt 31a. In this case, the injection nozzle 42a may be installed tilted relative to the vertical direction. In this case, the storage box 42b is installed taking into account the gas injection direction of the injection nozzle 42a.

The non-defective product recovery device 43 has a gas blowing section 43a, a discharge conveying section 43b, a drying device 43c, and a storage box (recovery box) 43d. This non-defective product recovery device 43 is provided downstream in the conveying direction A2 from the position where the reusable product recovery device 42 is provided, and the gas blowing section 43a, the drying device 43c, and the storage box 43d are provided in common to each conveying path P.

The gas blowing section 43a is provided at the end of the conveying device 31 of the second printing device 30, that is, at the end of the lower horizontal portion of the conveying belt 31a. For example, during the printing process, the gas blowing section 43a constantly blows gas (e.g., air) toward the conveying belt 31a, causing the tablets T to fall from the conveying belt 31a. At this time, the gas blown out from the gas blowing section 43a passes through the suction hole (similar to the suction hole 21g shown in FIG. 2) of the conveying belt 31a and hits the tablets T. As the gas blowing section 43a, for example, an air blower having a slit-shaped opening extending in a direction intersecting (e.g., perpendicular to) the conveying direction A2 in a horizontal plane can be used. The gas blowing section 43a is electrically connected to the control device 50, and its drive is controlled by the control device 50.

Here, the tablets T that have passed through the defective product recovery device 41 and the reusable product recovery device 42 are transported along with the movement of the conveyor belt 31a, and reach a position near the end of the conveyor belt 31a on the side of each driven pulley 31c. At this position, the suction effect on the tablets T is no longer applied, and gas is blown onto the tablets T from above by the gas blowing section 43a, causing the tablets T to fall from the conveyor belt 31a. By providing the gas blowing section 43a, the tablets T can be reliably dropped from the conveyor belt 31a.

The discharge conveying section 43b receives the tablets T that have passed through the defective product recovery device 41 and the reusable product recovery device 42, and conveys them in two or more rows to the storage box 43d. Note that, for example, a belt conveying mechanism can be used as the discharge conveying section 43b. The belt (good product conveying belt) of this discharge conveying section 43b is an endless belt that is gas permeable. As the gas permeable belt, it is possible to use belts made of various materials that have multiple through holes, such as a mesh belt or a belt with multiple round holes. The discharge conveying section 43b is electrically connected to the control device 50, and its drive is controlled by the control device 50.

The drying device 43c has an upper drying section 43c1 and a lower drying section 43c2. This drying device 43c dries the tablets T transported by the discharge conveying section 43b by the upper drying section 43c1 and the lower drying section 43c2 using dry gas (e.g., dry air). The upper drying section 43c1 is provided above the discharge conveying section 43b, and blows dry gas downward from an upper position of the discharge conveying section 43b. The lower drying section 43c2 is provided inside the discharge conveying section 43b, and blows dry gas upward from an internal position of the discharge conveying section 43b. These upper drying section 43c1 and lower drying section 43c2 are electrically connected to the control device 50, and their operation is controlled by the control device 50. As the upper drying section 43c1 and the lower drying section 43c2, in addition to devices that use dry gas for drying, various drying sections can be used, such as blowers that use gas such as air for drying, heaters that use radiant heat for drying, or blowers that use both gas and a heater for drying with warm or hot air.

The storage box 43d is located at the downstream end of the discharge/conveyance section 43b, i.e., the end of the discharge/conveyance section 43b opposite the second conveying device 31, and is provided outside the housing of the tablet printing device 1. This storage box 43d receives and stores tablets T whose ink has been dried by the drying device 43c from the discharge/conveyance section 43b.

The control device 50 includes an image processing unit 51, a print processing unit 52, an inspection processing unit (inspection unit) 53, and a storage unit 54. The image processing unit 51 processes images. The print processing unit 52 processes printing (described in detail later). The inspection processing unit 53 processes inspection. The storage unit 54 stores various information such as processing information and various programs. Such a control device 50 controls the supply device 10, the first printing device 20, the second printing device 30, and the collection device 40, and also receives position information of the tablets T transmitted from the individual detection devices 22 and 32 of the first printing device 20 and the second printing device 30, and images transmitted from the individual imaging devices 23, 25, 33, and 35 of the first printing device 20 and the second printing device 30. The operating conditions are set in advance and stored in the storage unit 54. The control device 50 controls each processing unit and the collection device 40 based on the operating conditions stored in the storage unit 54.

(Recovery Operation by Print Processing Unit 52, Inspection Processing Unit 53, and Reusable Product Recovery Device 42)
Next, the print processing unit 52, the inspection processing unit 53, and the recovery operation of the reusable product recovery device 42 will be described. The image processing unit 51 processes the images of the tablets T captured by the second imaging devices 25 and 35, and sends them to the inspection processing unit 53. The inspection processing unit 53 detects tablets T that have become defective due to poor ejection from these images, and counts the number of tablets. Here, a defective tablet due to poor ejection is one in which a part of the letters or marks printed on the surface of the tablet T is missing or chipped, or a part of the printed letters or marks is misaligned, and the inspection processing unit 53 judges it to be defective by comparing it with normal print data stored in advance in the memory unit 54. It can be estimated that such missing or chipped letters or marks are due to the fact that a part of the nozzles 24b and 34b of the print heads 24a and 34a is blocked by solidified ink and ink cannot be ejected normally. In addition, the landing misalignment also occurs when a part of the nozzles 24b and 34b is solidified, so that it takes more time to eject than usual even when ejection pressure is applied, resulting in the ink landing at a position shifted from the normal ejection position. Therefore, the inspection processing unit 53 counts the tablets T defective due to such ejection defects, distinguishing them from other defective tablets T (e.g., defective tablets due to appearance defects such as chipping or cracking). The second imaging devices 25, 35 and the inspection processing unit 53 function as a printing state confirmation device.

When the count of defective tablets T reaches a preset number (e.g., 5), the inspection processing unit 53 identifies the position (area) of the nozzle 24b, 34b with the defective discharge based on the image captured by the second imaging device 25, 35 as the defective discharge nozzle, and the print processing unit 52 prohibits printing using this defective discharge nozzle (a region including a single nozzle or multiple nozzles).

Next, the collection operation of the defective product collection device 41 and the collection operation of the reusable product collection device 42 will be described. The reusable product collection device 42 collects tablets T that cannot be printed due to the prohibition of printing using the defective nozzles described above. Based on the operating conditions, a collection operation is performed in which each injection nozzle 42a blows (gas injection). In other words, the reusable product collection device 42 collects tablets T that have not been printed. The defective product collection device 41 collects tablets with defective appearances described above and tablets that have been printed but have become defective due to defective injection. Based on the operating conditions, the defective product collection device 41 performs a collection operation in which each injection nozzle 41a blows (gas injection). In other words, the defective product collection device 41 collects tablets that cannot be made into good products by performing the printing process again.

If the inspection result of the inspection processing unit 53 indicates that the target tablet T is defective, or if there is a tablet T that cannot be printed because printing using a defective nozzle is prohibited, a blow is performed and the tablet is collected in the defective product recovery device 41 and the reusable product recovery device 42, respectively. Note that the blow is performed when the target tablet T reaches directly below the injection nozzles 41a, 42a based on the detection result by the detection unit of the detection device 32 (similar to the detection unit 22a of the detection device 22, and also referred to as the "tablet detection sensor"). This blow is performed in order to remove the target tablet T from the conveyor belt 31a.

(Printing process)
Next, a description will be given of the printing process and the inspection process performed by the above-mentioned tablet printing device 1. In the following printing process, a double-sided printing will be described in which identification information is printed on both sides of a tablet T having a score line formed on one side thereof so as to be aligned with the score line (for example, parallel to the extension direction of the score line).

First, various information such as print data required for printing is stored in the memory unit 54 of the control device 50. Then, when a large number of tablets T to be printed are fed into the hopper 11 of the supply device 10, the tablets T begin to be sequentially fed from the hopper 11 to the alignment feeder 12, which then moves them in two rows. The tablets T moving in these two rows are sequentially fed to the conveyor belt 21a of the first 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. Therefore, the tablets T supplied onto the conveyor belt 21a are conveyed in two rows on the conveyor belt 21a at a predetermined moving speed. The conveyor belt 31a is also rotated in the conveying direction A2 by the rotation of the drive pulley 31b and each driven pulley 31c by the motor 31d.

In the first printing device 20, the tablet T is sucked and held on the conveyor belt 21a, and the tablet T on the conveyor belt 21a is detected by the detection device 22. As a result, position information of the tablet T (position in the conveying direction A1) is acquired and input to the control device 50. This position information of the tablet T is stored in the memory unit 54 and used in post-processing. Next, the tablet T on the conveyor belt 21a is imaged by the first imaging device 23 at a timing based on the position information of the tablet T described above, and the imaged image is transmitted to the control device 50. Based on each image transmitted from the first imaging device 23, positional deviation information of the tablet T (for example, positional deviation of the tablet T in the X direction, Y direction, and θ direction in FIG. 2) is generated by the image processing unit 51 and stored in the memory unit 54. Based on this positional deviation information of the tablet T, the printing conditions for the tablet T (such as the ink ejection position and ejection speed) are set by the print processing unit 52 and stored in the memory unit 54.

Next, each tablet T on the conveyor belt 21a is printed by the print head device 24 based on the print data and printing conditions described above at a timing based on the position information of the tablet T described above, i.e., when the tablet T reaches below the print head device 24. In each print head 24a of the print head device 24, ink is appropriately ejected from each nozzle 24b, and identification information such as letters (e.g., alphabets, katakana, numbers) and marks (e.g., symbols, figures) are printed on the upper surface of the tablet T aligned with the score line (e.g., parallel to the extension direction of the score line).

The tablet T on which the identification information is printed is imaged by the second imaging device 25 at a timing based on the position information of the tablet T described above, and the image is transmitted to the control device 50. Based on each image transmitted from the second imaging device 25, the image processing unit 51 generates printing position information indicating the printing position of the printing pattern for each tablet T, and stores it in the memory unit 54. Based on the printing position information, the inspection processing unit 53 judges whether the printing quality of the tablet T is good or bad (whether the tablet T is a good product or not), and the inspection result information indicating the printing quality of each tablet T and the appearance such as cracks and chips is stored in the memory unit 54. For example, the inspection processing unit 53 judges whether the printing pattern is printed in a predetermined pattern at a predetermined position on the tablet T. The tablet T that is judged to be printed in a predetermined pattern at a predetermined position on the tablet T is considered to be a good tablet T that has passed the inspection.

The inspection processing unit 53 counts the number of tablets T with defective ejection among the tablets T that have failed the inspection, and when it reaches a preset number (e.g., 5), it identifies the position (area) of the nozzle 24b, 34b with the defective ejection based on the image captured by the second imaging device 25, 35 as a defective ejection nozzle, and the print processing unit 52 prohibits printing using this defective ejection nozzle (an area including a single nozzle or multiple nozzles).

After inspection, the tablet T is transported by the movement of the conveyor belt 21a and passes above the drying device 26, which is in the drying operation. At this time, the ink that has reached (landed on) the tablet T is dried by the drying device 26 as the tablet T passes above the drying device 26, and the tablet T with the dried ink is transported by the movement of the conveyor belt 21a and is positioned near the end of the conveyor belt 21a on the side of each driven pulley 21c. At this position, the suction effect no longer acts on the tablet T, and the tablet T is released from the state held on the underside of the conveyor belt 21a and is passed from the first printing device 20 to the second printing device 30.

In the second printing device 30, the tablets T are sucked and held on the conveyor belt 31a, and the printing process and inspection process are performed in the same manner as described above. The tablets T after inspection are transported along with the movement of the conveyor belt 31a and pass above the drying device 36 during the drying operation. Then, the tablets T with the dried ink reach the defective product collection device 41. At this position, tablets T other than good products (defective products and unknown products) fall from the underside of the conveyor belt 31a by the gas injection (blow) from the injection nozzle 41a and are collected by the storage box 41b. In addition, good tablets T or tablets T other than good products that did not fall from the conveyor belt 31a by the blow pass through the defective product collection device 41 and reach a position near the end of the conveyor belt 31a on the side of each driven pulley 31c. At this position, the suction action no longer works on the tablets T and they fall. Furthermore, gas is blown onto the tablets T from above by the gas blowing section 43a, so that the tablets T fall reliably from the conveyor belt 31a. The tablets T that fall from the conveyor belt 31a flow into the discharge conveyor section 43b.

The tablets T that flow into the discharge conveying section 43b are conveyed by the discharge conveying section 43b, and during the conveying, the tablets T pass between the upper drying section 43c1 and the lower drying section 43c2 (drying space) of the drying device 43c that is in the drying operation. The tablets T on the belt of the discharge conveying section 43b are sprayed with dry gas from the upper drying section 43c1 and the lower drying section 43c2, so that the ink on the tablets T is dried and the dry state of the tablets T is maintained. Even if the tablets T contain moisture due to humidity in the conveying path P upstream of the discharge conveying section 43b, the ink on the tablets T can be reliably dried by the upper drying section 43c1 and the lower drying section 43c2 while the tablets T are being conveyed by the discharge conveying section 43b. At this time, the conveying speed of the discharge conveying section 43b is much slower than the conveying speed during printing, so that the tablets T on the belt pass through the space of dry gas slowly for about ten minutes, and the ink on the tablets T is reliably dried. The tablets T dried by the drying device 43c are transported by the discharge conveying section 43b to above the storage box 43d, drop from the downstream end of the discharge conveying section 43b, and are collected in the storage box 43d.

Here, the printing process when printing using a defective nozzle is prohibited by the inspection processing unit 53 will be described using the flowchart of FIG. 3. As the printing process proceeds in the order described above, the inspection processing unit 53 counts the number of tablets T that are defective due to defective ejection and determines whether this number exceeds a predetermined number (S1). If the number of tablets T with defective ejection exceeds a predetermined number (Y in S1), the shutter (not shown) provided at the outlet of the supply device 10 is closed to stop the supply of new tablets T to the first printing device 20, and the printing process is continued for the tablets T that are being transported at this time (S2). Here, the inspection processing unit 53 identifies the defective ejection nozzle (including the area) (S3) and sets the respective printing conditions based on the images of the tablets T that are sequentially captured by the first imaging device 23 (S4) (S5). Based on these printing conditions, it is determined whether the tablet T is to be printed using the defective ejection nozzle (S6). If the printing is to be performed using the defective ejection nozzle (Y in S6), printing is prohibited as described above (S7). That is, if there is a nozzle 24b of the print head 24a of the first printing device 20 that is defective in ejection, printing is not performed by the print heads 24a and 34a on the tablets T for which the defective nozzle is used for printing as a result of the printing conditions being set based on the position information of the tablets T obtained by the first imaging device 23. In this way, the tablets T that are not printed by the print heads 24a and 34a are collected by the reusable product recovery device 42. If the printing is not performed using the defective nozzle (N in S6), printing is continued (S8). That is, as a result of the printing conditions being set based on the position information of the tablets T obtained by the first imaging device 23, the printing process is performed as usual on the tablets for which the defective nozzle is not used for printing, and the tablets are collected by the recovery device 40. In this way, printing is continued, and when printing of the planned number of tablets T (all tablets T in the middle of transportation) is completed (Y in S9), production is terminated.

If there is a nozzle 34b of the print head 34 of the second printing device 30 that is defective, the defective nozzle is identified based on the results of the second imaging device 35, and the print processing unit 52 prohibits printing using the defective nozzle. As a result of setting the printing conditions based on the position information of the tablet T obtained by the first imaging device 33, printing is not performed by the print head 34a for the tablet T for which the defective nozzle is to be used for printing. At this time, the tablet T that has already been printed on one side by the first printing device 20 is transported to the second printing device 30. Therefore, even if printing is not performed by the print head 34a of the second printing device 30, this tablet T is collected by the defective product collection device 41, not the reusable product collection device 42.

When collection by the collection device 40 is complete and there are no tablets T in the first printing device 20 or the second printing device 30, the control device 50 performs maintenance on the print head devices 24 and 34. Maintenance of the print head devices is performed by known means such as wiping with a wiper, immersion in cleaning liquid, or dummy ejection into a drain pan. When maintenance is complete, the control device 50 opens the shutter provided at the outlet of the supply device 10 and resumes normal printing processing.

As described above, according to the first embodiment, even if a nozzle with a defective ejection function occurs, printing can be continued without interrupting printing to perform maintenance on the print head device, and the occurrence of defective products due to the defective nozzle can be suppressed, so that the printing process of the tablets T can be carried out efficiently. In addition, the tablets T that were not printed are separated from other defective tablets T and collected by the reuse collection device 42, so that they can be printed again.

Here, in the case of conventional methods where the print head device is maintained every time a defective printing nozzle is found, the transport of tablets is stopped, printing is interrupted, and all tablets T present in the device at that time are collected by a collection device, and maintenance of the print head device is carried out. When maintenance is completed, tablets T are again supplied to the supply device 10 and printing is resumed. In contrast, in the first embodiment, when a defective tablet T due to a discharge defect is detected, tablets T that can be printed by a nozzle other than the problem nozzle are printed, while tablets T present in the tablet printing device 1 at that time can be collected, so that the time until maintenance can be performed can be used effectively.

The diameter of the tablet T to be printed by the tablet printing device 1 is generally about 5 to 12 mm, which is shorter than the length of a typical inkjet head extending in the nozzle arrangement direction. The tablets T are transported randomly around the center of the print heads 24a and 34a in a direction perpendicular to the transport direction of the transport belts 21a and 31a (see FIG. 2). A nozzle with poor ejection is often caused by not using the nozzle for a certain period of time. In other words, it is thought that the randomly transported tablets T are printed using the nozzles 24b and 34b that happen to be used infrequently, resulting in poor printing. In other words, the nozzles 24b and 34b that have become nozzles with poor ejection are likely to have been used infrequently to begin with, and it can be said that the possibility of the tablets T to be printed by those nozzles is relatively low. Therefore, it is possible to perform the printing process significantly more efficiently by continuing printing as in the first embodiment than by performing maintenance every time a printing failure occurs as in the conventional method.

<Other embodiments>
In the above embodiment, when the number of tablets T that are defective due to ejection defects exceeds a predetermined number, the new supply of tablets T is stopped, the ejection defective nozzle is identified, and the printing process is continued while prohibiting printing using this nozzle, but this is not limited to the above. For example, the printing process that does not use the ejection defective nozzle may be continued without stopping the new supply of tablets T. In this case, when the ejection defective nozzle is identified, the time required until the end of production is predicted in the case where the remaining tablets up to the planned production number are printed without using the nozzle and in the case where the operation of the device is temporarily stopped and maintenance is performed, and as a result of comparing the predicted times, if the predicted end time of production is earlier when the operation is temporarily stopped and maintenance is performed, maintenance may be performed.

For example, when there are 10,000 tablets remaining to be produced, a comparison is made between continuing printing without using the defective nozzle and pausing printing to perform maintenance and then printing to see which method can complete printing of 10,000 tablets faster. When printing tablets having a score line or an elliptical shape, the tablet printing device 1 stores a print pattern rotated 360 degrees in advance, and selects a print pattern based on the positional deviation information in the θ direction obtained from the image of the tablet T captured by the first imaging device 23, 33, and stores it in the memory unit 54. From this print pattern, the angle range in which printing will be performed using the defective nozzle is obtained, and the probability that tablets T that require printing in this angle range will be conveyed (i.e., the percentage of tablets T that will be collected by the recyclable product collection device 42) is calculated. This probability (estimate) can be calculated by determining the proportion of tablets T that fall within the angle range to be printed using the defective nozzle from the history of the deviation in the θ direction of the tablet obtained until the defective nozzle is detected. If the probability of a tablet T being conveyed having a θ direction deviation within the angle range that uses the defective ejection nozzle is, for example, about 20%, production efficiency will decrease by 20%, and the time to print 10,000 tablets will be delayed by that amount. The predicted production end time derived in this way can be compared with the predicted production end time when printing is temporarily stopped and maintenance is performed, and the earlier one can be selected. For example, two predicted production end times can be displayed on the display device of the tablet printing device 1 so that the operator can select one.

In the above explanation, a fixed planned production quantity is, for example, 10,000 tablets, but this is not limiting and the determination may be made based on the remaining number of tablets T contained in the hopper 11. For example, the remaining amount of tablets T may be detected by a sensor (not shown) provided in the hopper 11, and if it falls below a predetermined amount, printing may be continued, and if it exceeds the predetermined amount, printing may be interrupted and maintenance may be performed. The predetermined amount is determined in advance taking into consideration the time it takes for the tablets T to be supplied, printed, and collected, and the time until the next scheduled regular maintenance.

In addition, the decision as to whether to continue printing may be made by taking into consideration both production efficiency and the remaining amount. In other words, if it is predicted that the production efficiency calculated based on the angle range in which the defective nozzle is used will drop significantly, printing may be interrupted and maintenance may be performed, and if the production efficiency does not drop significantly (for example, about 20%, as in the previous example) and the remaining amount falls below a predetermined amount, printing may be continued, and if the production efficiency does not drop significantly but the remaining amount exceeds the predetermined amount, printing may be interrupted.

By making this selection possible, printing can be performed most efficiently if an inkjet head fails to eject ink.

In the above explanation, an example was given of transporting tablets T in two rows, but this is not limited thereto, and the number of rows may be one, three, four or more rows, and the number of transport paths P and the number of transport belts 21a, 31a are not particularly limited. Furthermore, the shape of the suction holes 21g of the transport belts 21a, 31a is not particularly limited.

In addition, in the above explanation, an example was given of a print head 24a being provided for each transport path P, but this is not limited to this, and for example, one print head 24a may be used to print on two or more rows of tablets T.

In the above explanation, a print head in which nozzles 24b are arranged in a single row is used as the inkjet print head 24a, but this is not limited thereto. For example, a print head in which nozzles 24b are arranged in multiple rows may be used. Also, multiple print heads 24a may be arranged along the transport direction A1.

In addition, in the above explanation, the provision of drying devices 26, 36, and 43c was exemplified, but the number is not limited. For example, two drying devices 36 and 43c may be provided instead of one drying device 26, or one drying device 43c may be provided instead of two drying devices 26 and 36, or drying devices 26 and 36 may be provided instead of drying device 43c. Also, depending on the type of ink and tablets T, a drying device may not be required, so all three drying devices 26, 36, and 43c may not be provided.

In addition, in the above explanation, the first printing device 20 and the second printing device 30 are stacked one on top of the other to print both sides or one side of the tablet T, but this is not limited to this. For example, it is also possible to provide only the first printing device 20 and print only one side of the tablet T.

In addition, in the above explanation, an example was given in which the reusable product recovery device 42 is provided downstream of the defective product recovery device 41, but this is not limited thereto, and the reusable product recovery device 42 may be provided upstream of the defective product recovery device 41.

In addition, in the above explanation, when a nozzle with a defective ejection function is present in the print head 34a of the second printing device 30, printing is performed in the print head 24a of the first printing device 20, and then the tablets are collected in the defective product collection device 41 without printing using the print head 34a of the second printing device. However, this is not limited to this, and only the tablets T that have been printed on only one side may be collected separately. In this case, the tablets T that have been printed on only one side can be re-introduced into the tablet printing device 1, and printing can be performed only on the side that has not been printed.

Alternatively, if the print head 34a of the second printing device 30 has a nozzle with a defective ejection function, and it is predicted that the print head 34a of the second printing device 30 will be used at the time that the positional deviation information of the tablet T is generated based on the image captured by the first imaging device 23 of the first printing device 20, the print head 24a of the first printing device may also be collected by the reusable product collection device 42 without printing.

Here, the aforementioned tablet T can include tablets used for medicine, food, cleaning, industrial or aromatic purposes. Tablets include uncoated tablets, sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multi-layered tablets, dry-coated tablets, and various capsule tablets such as hard capsules and soft capsules. Tablet shapes include disks, lenses, triangles, ovals, and various other shapes. When the tablet to be printed is for medicine or food, edible ink is suitable for use. As the edible ink, any of synthetic dye ink, natural dye ink, dye ink, and pigment ink may be used.

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

1. Tablet printing device
21, 31 Conveyor device
23, 33 First imaging device
24, 34 Print head device
25, 35 Second imaging device
41 Defective product recovery device 42 Re-inspection product recovery device
4 3 Good product recovery device
5 0 Control device (control unit)
52 Print processing unit 53 Inspection processing unit (inspection unit)
T Tablet

Claims (7)

A conveying device for conveying tablets;
An imaging device that images the tablet transported by the transport device ;
a print head device that prints on the tablet downstream of the imaging device in a conveying direction of the tablet conveyed by the conveying device ;
a print status confirmation device that is downstream of the print head device in the conveying direction and that confirms the print status of the tablet;
a control unit that controls a printing process by the print head device,
The control unit generates positional deviation information of the tablet based on an image captured by the imaging device, and sets printing conditions for the tablet based on the positional deviation information,
The control unit identifies the position of the faulty nozzle in the print head device based on the results of the printing status confirmation device, and if the printing conditions set based on the misalignment information are printing conditions that use the faulty nozzle, prohibits printing using those printing conditions , and if the printing conditions set based on the misalignment information are printing conditions that do not use the faulty nozzle, controls the tablet printing device to print using those printing conditions . A first printing device for printing on one side of the tablet;
A second printing device is disposed downstream of the first printing device and prints on the other side of the tablet,
the imaging device and the print head device are provided in the first printing device and the second printing device, respectively;
The tablet printing device described in claim 1, characterized in that when the print head device provided in the first printing device has the defective nozzle and the printing conditions are printing conditions that use the defective nozzle of the print head device in the first printing device, the control unit prohibits printing by the print head device in the first printing device and also does not print by the print head device in the second printing device. A first printing device for printing on one side of the tablet;
A second printing device is disposed downstream of the first printing device and prints on the other side of the tablet,
the imaging device and the print head device are provided in the first printing device and the second printing device, respectively;
The control unit, when the print head device provided in the second printing device has the defective nozzle, generates positional misalignment information of the tablet based on an image captured by the imaging device of the first printing device, sets printing conditions for the tablet in the second printing device based on the positional misalignment information, and, when the printing conditions are printing conditions that use the defective nozzle of the print head device in the second printing device, controls the print head device of the first printing device so that printing is not performed either. The tablet printing device described in claim 1 , characterized in that A first printing device for printing on one side of the tablet;
a second printing device downstream of the first printing device for printing on the other side of the tablet;
a recovery device provided downstream of the first printing device and the second printing device and configured to recover the tablets;
the print head device is provided in each of the first printing device and the second printing device,
The recovery device includes a non-defective product recovery device that recovers the tablets that are non-defective products that have been normally printed by the first printing device and the second printing device, and a defective product recovery device that recovers the tablets that are defective products that have not been normally printed by at least one of the first printing device and the second printing device.
The tablet printing device described in claim 1, characterized in that when the faulty nozzle is present in the second printing device, the control unit prohibits printing under printing conditions that use the faulty nozzle of the print head device in the second printing device, resulting in printing of one side of the tablet by the first printing device being performed normally, and a recovery device that recovers the tablet on which printing could not be performed on the other side. conveying the tablets by a conveying device ;
An imaging step of imaging the tablet transported by the transport device ;
A step of performing printing by a print head device downstream of the imaging step in a conveying direction of the tablet conveyed by the conveying device ;
A print state confirmation step of confirming the print state of the tablet downstream of the print head device in the conveying direction,
Generate positional deviation information of the tablet based on the image captured in the imaging step, and set printing conditions for the tablet based on the positional deviation information.
A tablet printing method characterized in that the position of a faulty nozzle in the print head device is identified based on the results of the printing state confirmation process, and if the printing conditions set based on the position misalignment information are printing conditions that use the faulty nozzle, printing using those printing conditions is not performed , and if the printing conditions do not use the faulty nozzle, printing is performed using those printing conditions . The imaging step and the printing step are performed in a first printing device that performs a printing process on one side of the tablet and a second printing device that performs a printing process on the other side of the tablet downstream of the first printing device,
The tablet printing method described in claim 5, characterized in that when the print head device provided in the first printing device has the faulty nozzle and the printing conditions are printing conditions that use the faulty nozzle of the print head device in the first printing device, printing is not performed by the print head device in the first printing device, and printing is also not performed by the print head device in the second printing device . The imaging step and the printing step are performed in a first printing device that performs a printing process on one side of the tablet and a second printing device that performs a printing process on the other side of the tablet downstream of the first printing device,
The tablet printing method described in claim 5, characterized in that when the print head device provided in the second printing device has the defective nozzle, positional deviation information of the tablet is generated based on an image captured by the imaging process of the first printing device, printing conditions for the tablet in the second printing device are set based on the positional deviation information, and when the printing conditions are printing conditions that use the defective nozzle of the print head device in the second printing device, printing is not performed in the print head device of the first printing device either.

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