JP7812415B2 - Tablet printing device and tablet manufacturing method - Google Patents

Description

The present invention relates to a tablet printing device and a tablet manufacturing method.

A tablet printing device such as that described in Patent Document 1 has been known for some time. This tablet printing device sequentially transports tablets using a conveyor belt. An inkjet printer, a printing device installed opposite the tablets on the conveyor belt, then prints identification characters, marks, etc. on the surfaces of the tablets.

Inkjet printers have a print head equipped with multiple nozzles that eject ink droplets. The multiple nozzles in the print head print by ejecting ink droplets according to a pattern based on print data.

When using such an inkjet printer, even if the letters or marks to be printed change due to a change in tablet type, etc., it is possible to respond immediately by changing the print data provided. Inkjet printers also allow for non-contact printing, making them hygienic and suitable for printing on tablets that are intended for consumption.

Japanese Unexamined Patent Publication No. 7-081050

Some tablets have a glossy surface, such as sugar-coated tablets and FC (film-coated) tablets. These glossy tablets have a smooth, shiny surface that easily repels ink when printed on. This can lead to printing defects, such as the desired pattern not being printed or the printed pattern looking poor. For example, in the case of oral tablets, if such printing defects occur, there will be problems with the quality of the product, even if there are no problems with drinking the tablet.

To address this issue, one option is to use a high-viscosity ink that adheres relatively well to the tablet surface, thereby reducing ink repelling. However, high-viscosity ink has poor ejection properties from the nozzles of the print head, and is prone to ejection problems, not just in inkjet printing. Poor ejection can lead to print defects such as chipped or missing prints, or faint prints.

The present invention has been proposed to solve the problems described above, and its purpose is to provide a tablet printing device and tablet manufacturing method that can reduce printing defects on tablets.

In order to achieve the above object, the tablet printing apparatus of the present invention comprises a conveying device that conveys a plurality of coated tablets along a conveying path while suction-holding one side of the tablet by a suction hole and conveys the tablets along the conveying path while suction-holding the other side of the tablet by a suction hole; a first plasma generating device that sprays a gas flow containing products of atmospheric pressure plasma from a first outlet onto the other side of the tablet that is conveyed while suction-holding the one side; a first inkjet print head device that is arranged downstream of the first outlet in the tablet conveying direction and prints on the other side of the tablet that is conveyed by the conveying device and onto which the gas flow has been sprayed; and a second print head device that is arranged downstream of the first print head device in the tablet conveying direction and conveys the other side of the tablet that is conveyed while suction-holding the other side. The device comprises a second plasma generating device that sprays a gas flow containing products generated by atmospheric pressure plasma onto one side of the tablet from a second outlet, and a second inkjet printing head device that is positioned downstream of the second outlet in the conveying direction and is capable of printing on one side of the tablet being conveyed to the conveying device, wherein the first outlet is located at a position facing the other side of the tablet that is sucked and held by the suction hole, the second outlet is located at a position facing the one side of the tablet that is sucked and held by the suction hole, and the suction hole located between the tablets being conveyed by the conveying device sucks in the products contained in the gas flow sprayed from the first outlet and the second outlet .

The tablet manufacturing method of the present invention includes the steps of: suction-holding one side of a plurality of coated tablets by a plurality of suction holes provided in a conveyor belt and conveying them; spraying a gas flow containing products of atmospheric pressure plasma from a first outlet provided at a position facing the other side of the tablets; and printing the other side onto which the gas flow has been sprayed using a first inkjet print head device; suction-holding the other side of the tablets printed by the first print head device by the suction holes and conveying them; spraying a gas flow containing products of atmospheric pressure plasma from a second outlet provided at a position facing the one side of the tablets printed by the first print head device; and printing the one side onto which the gas flow has been sprayed from the second outlet using a second inkjet print head device; and the suction holes located between the tablets conveyed by the conveyor belt suck in the products contained in the gas flows sprayed from the first and second outlets .

The present invention provides a tablet printing device and tablet manufacturing method that can reduce printing defects on tablets.

1 is a diagram schematically illustrating the overall configuration of a tablet printing apparatus according to an embodiment. FIG. FIG. 1 is a diagram showing tablets placed on a conveyor belt as viewed from above. FIG. 1 is a diagram showing a plasma generating device. This is an image (A) of a tablet printed on the printing surface without spraying atmospheric pressure plasma products, and an enlarged image (B) of the printed text portion. This is an image (A) of a tablet printed on a printing surface onto which atmospheric pressure plasma products have been sprayed, and an enlarged image (B) of the printed text portion. 1A is a side view and FIG. 1B is a plan view showing a state in which the product is sprayed from a plurality of nozzles onto the tablets being conveyed. 1A is a side view and FIG. 1B is a plan view showing a state in which the product is sprayed onto the tablets being conveyed from a nozzle that is long in the conveying direction. FIG. 10 is a cross-sectional view showing an embodiment in which a plasma generating device is provided in a supply device. 1A is a side view and FIG. 1B is a plan view showing a state in which a product from a plasma generator is sprayed onto a rounded rectangular tablet.

Embodiments of the present invention will be described with reference to the drawings. In the following description, "upper" and "lower" refer to upper and lower in the vertical direction. Coated tablets are used as tablets T. Coated tablets have a glossy surface, such as sugar-coated tablets and film-coated tablets. Furthermore, the shape of tablet T is that of a circular convex lens, with a pair of opposing dome-shaped curved surfaces serving as the printing surfaces.

(Basic configuration)
1, the tablet printing apparatus 1 of this embodiment includes a supply device 10, an alignment/transport device 11, a first printing device 20, a second printing device 30, a recovery device 40, and a control device 50. The first printing device 20 and the second printing device 30 basically have the same structure. Furthermore, this embodiment includes a plasma generation device 100 that generates atmospheric pressure plasma.

As described below, the components of the tablet printing device 1, namely the supply device 10, the alignment and conveying device 11, the first printing device 20, the second printing device 30, and the recovery device 40, are arranged in this order. Tablets T supplied to the supply device 10 undergo a series of processes, including printing and recovery, as they are transported along the transport path P. The transport path P is the path along which tablets T are transported in the tablet printing device 1; in this embodiment, the supply device 10 is located upstream of the transport path P, and the recovery device 40 is located downstream.

The supply device 10 is positioned at one end of the alignment/conveyance device 11, i.e., at the upstream end in the conveying direction A1 of the tablets T (hereinafter simply referred to as the conveying direction A1). The supply device 10 is electrically connected to the control device 50, and its drive is controlled by the control device 50.

The supply device 10 has a hopper 10a, a duct 10b, and a vibrating feeder (chute) 10c. The hopper 10a stores a large number of tablets T and sequentially supplies the stored tablets T to the duct 10b. The duct 10b is connected to the underside of the hopper 10a and supplies each tablet T supplied from the hopper 10a to the vibrating feeder 10c. The vibrating feeder 10c vibrates each tablet T supplied from the underside of the duct 10b to eliminate overlapping of the tablets T, while supplying each tablet T to the aligning and conveying device 11. In this supply device 10, the tablets T fall and move under their own weight, but for convenience in this specification, the supply device 10 will also be referred to as "conveying tablets T."

In this supply device 10, for example, 100,000 tablets T per hour (100,000 tablets/H) are fed into the hopper 10a, but not all of the tablets T fed into the hopper 10a immediately pass through the duct 10b and vibrating feeder 10c and are supplied to the aligning and conveying device 11. A large number of tablets T will temporarily remain in the hopper 10a, duct 10b, and vibrating feeder 10c.

The aligning and conveying device 11 has an alignment feeder 13 and a transfer feeder 14. This aligning and conveying device 11 is positioned at one end of the first printing device 20, i.e., at the upstream end in the conveying direction A1. The aligning and conveying device 11 is configured to be able to supply tablets T to the first printing device 20 using the alignment feeder 13 and transfer feeder 14. This aligning and conveying device 11 is electrically connected to the control device 50, and its drive is controlled by the control device 50.

The alignment feeder 13 aligns the supplied tablets T in two rows and transports them toward the transfer feeder 14. The transfer feeder 14 sequentially sucks in and holds each tablet T arranged in two rows on the alignment feeder 13 from the top side of the tablet T, transports the held tablets T in two rows to the first printing device 20, and hands them over to the first printing device 20. Note that the alignment feeder 13 and the transfer feeder 14 can be, for example, a belt conveyance mechanism.

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

The conveying device 21 includes a conveying belt 21a, a driving pulley 21b, multiple (three in the example of Figure 1) driven pulleys 21c, a motor 21d, a position detector 21e, and a suction chamber 21f. The conveying belt 21a is an endless belt that 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. The 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, described below, can obtain information such as the position, speed, and movement amount of the conveying belt 21a based on the detection signal. In this conveying device 21, the drive pulley 21b is rotated by the motor 21d, which rotates the conveying belt 21a together with the driven pulleys 21c, and the tablets T on the conveying belt 21a are conveyed in the direction of arrow A1 in Figure 1 (conveying direction A1).

As shown in Figure 2, a plurality of circular suction holes 21g are formed on the surface of the conveyor belt 21a. Each of these suction holes 21g is a through-hole that adsorbs tablets T to the surface of the conveyor belt 21a, and is arranged in two parallel rows along the conveying direction A1 to form two conveying paths. Each suction hole 21g is connected to the inside of the suction chamber 21f via a suction path formed in the suction chamber 21f, allowing suction force to be generated by the suction chamber 21f. An intake device such as a pump is connected to the suction chamber 21f via an intake pipe (neither is shown), and the pressure inside the suction chamber 21f is reduced by operating the intake device. The intake device is also electrically connected to the control device 50, and its operation is controlled by the control device 50.

The detection device 22 has multiple detection units 22a (two in the example shown in Figure 2). The detection units 22a are arranged one for each conveyance path of the tablets T, downstream in the conveying direction A1 from the position on the conveyor belt 21a where the tablets T are supplied by the aligning and conveying device 11, in a direction intersecting (e.g., perpendicular to) the conveying direction A1 in the horizontal plane, and are provided above the conveyor belt 21a. The detection units 22a detect the position of the tablets T on the conveyor belt 21a (position in the conveying direction A1) and function as trigger sensors for each device located downstream. Various 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 (position information) to the control device 50.

The first imaging device 23 has multiple imaging units 23a (two in the example shown in Figure 2). The imaging units 23a are arranged downstream in the conveying direction A1 from the position where the detection device 22 is provided, in a direction intersecting (e.g., perpendicular to) the conveying direction A1 in the horizontal plane, one for each conveying path of the tablets T, and are provided above the conveyor belt 21a. Based on the position information of the tablets T described above, the imaging units 23a capture images of the tablets T when they arrive directly below the imaging units 23a, obtain images including the top surfaces of the tablets T (images for printing), and transmit the obtained images to the control device 50. The imaging units 23a can be various cameras equipped with imaging elements such as CCDs (charge-coupled devices) or CMOSs (complementary metal-oxide semiconductors). Each imaging unit 23a is electrically connected to the control device 50, and its operation is controlled by the control device 50. Illumination for imaging is also provided as needed.

The print head device 24 is a device that prints on the printing surface of the tablet T. The print head device 24 of this embodiment has multiple inkjet print heads 24a (two in the example shown in Figure 2). The print heads 24a are arranged downstream in the conveying direction A1 from the position where the first imaging device 23 is installed, in a direction that intersects (e.g., perpendicular to) the conveying direction A1 in the horizontal plane, one for each conveying path of the tablet T, and are installed above the conveying belt 21a. The print head 24a has multiple nozzles 24b (see Figure 2; however, only four are shown in the illustration), and ink is ejected individually from each nozzle 24b. The print head 24a is installed so that the alignment direction of the nozzles 24b intersects (e.g., perpendicular to) the conveying direction A1 in the horizontal plane. Various inkjet print heads having drive elements such as piezoelectric elements, heating elements, or magnetostrictive elements can be used as the print head 24a. Each print head 24a is electrically connected to the control device 50, and their operation is controlled by the control device 50.

The second imaging device 25 has multiple imaging units 25a (two in the example shown in Figure 2). The imaging units 25a are arranged downstream in the conveying direction A1 from the position where the print head device 24 is provided, and aligned one for each tablet T conveyance path in a direction intersecting (e.g., perpendicular to) the conveying direction A1 in the horizontal plane, above the conveyor belt 21a. Based on the position information of the tablet T described above, the imaging units 25a capture images of the tablets T when they arrive directly below the imaging units 25a, and acquire images (images for inspection) including the top surfaces of the tablets T. The imaging units 25a then transmit the acquired images to the control device 50. Similar to the imaging unit 23a described above, various cameras equipped with imaging elements such as CCDs and CMOSs can be used as the imaging units 25a. Each imaging unit 25a is electrically connected to the control device 50, and its operation is controlled by the control device 50. Illumination for imaging is also provided as needed.

Returning to Figure 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 common to both rows of conveying paths and dries the ink applied to each tablet T on the conveying belt 21a. The drying device 26 can be any of a variety of drying units, including 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 using both gas and a heater. The drying device 26 is electrically connected to the control device 50, and its operation 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 driven pulley 21c side. At this position, the suction action on the tablets T ceases, and the tablets T are released from their position on the conveyor belt 21a and are transferred from the first printing device 20 to the second printing device 30.

The second printing device 30 comprises a conveying device 31, a detecting 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 comprises a conveying belt 31a, a driving pulley 31b, multiple (three in the example of Figure 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 essentially the same structure as the corresponding component of the first printing device 20 described above, and therefore a description thereof will be omitted. The conveying direction of the second printing device 30 is the direction of arrow A2 in Figure 1 (conveying direction A2).

The recovery device 40 includes a defective product recovery device 41 and a non-defective product recovery device 42. This recovery device 40 is located downstream in the conveying direction A2 from the position where the drying device 36 of the second printing device 30 is located. The defective product recovery device 41 recovers defective tablets T, and the non-defective product recovery device 42 recovers non-defective tablets T. Note that defective tablets T are, for example, tablets T with cracks or chips detected based on images acquired by the imaging devices 23 and 33, tablets T whose pre-printing positional deviation exceeds an allowable value, or tablets T whose printing position exceeds an allowable value, detected based on images acquired by the imaging devices 25 and 35.

The defective product recovery device 41 has a spray nozzle 41a and a storage device 41b. The spray nozzle 41a is provided in the suction chamber 31f of the second printing device 30. This spray nozzle 41a sprays gas (e.g., air) toward tablets T (defective tablets T) being transported by the conveyor belt 31a, causing the tablets T to fall from the conveyor belt 31a. At this time, the gas sprayed from the spray nozzle 41a passes through suction holes 31g (similar to suction holes 21g shown in Figure 2) in the conveyor belt 31a and hits the tablets T. The spray nozzle 41a is electrically connected to the control device 50, and its operation is controlled by the control device 50. The storage device 41b receives and stores the tablets T that have fallen from the conveyor belt 31a.

The non-defective product collection device 42 has a gas blowing section 42a and a storage device 42b. This non-defective product collection device 42 is located downstream in the conveying direction A2 from the position where the defective product collection device 41 is located.

The gas blowing unit 42a is located within the conveying device 31 of the second printing device 30 and is provided at the end of the conveying device 31 (i.e., the end of the conveying belt 31a on the driven pulley 31c side). For example, during printing, the gas blowing unit 42a constantly blows gas (e.g., air) toward the conveying belt 31a, causing tablets T to fall from the conveying belt 31a. At this time, the gas blown out from the gas blowing unit 42a passes through the suction holes 31g (similar to the suction holes 21g shown in FIG. 2) of the conveying belt 31a and hits the tablets T. The gas blowing unit 42a can be, for example, an air blower with a slit-shaped opening extending in a direction intersecting (e.g., perpendicular to) the conveying direction A2 in the horizontal plane. The gas blowing unit 42a is electrically connected to the control device 50, and its operation is controlled by the control device 50.

Here, tablets T that have passed through the defective product collection device 41 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 driven pulley 31c side. At this position, the suction effect on the tablets T ceases, and by providing a gas blowing section 42a, the tablets T can be dropped from the conveyor belt 31a into the storage device 42b.

The storage device 42b receives and stores tablets T that have fallen from the underside of the conveyor belt 31a. The storage device 42b is positioned at the downstream end of the conveyor belt 31a, i.e., the conveying end of the second conveyor device 31 in the second printing device 30, and is located outside the housing of the tablet printing device 1.

(Plasma generator)
The plasma generator 100 is a device that generates atmospheric pressure plasma. As shown in FIG. 1 , the plasma generator 100 sprays a product of atmospheric pressure plasma onto the printing surface of the tablet T from an outlet 101. The product is sprayed simultaneously with the blowing of process gas. In other words, a gas flow containing the product is sprayed onto the printing surface of the tablet T. The plasma generator 100 is provided in each of the first printing device 20 and the second printing device 30. Hereinafter, the device provided in the first printing device 20 will be referred to as plasma generator 100A, and the device provided in the second printing device 30 will be referred to as plasma generator 100B, but when there is no need to distinguish between the two, they will be referred to as plasma generator 100.

The aforementioned print head devices 24, 34 are positioned downstream of the air outlet 101 in the conveying directions A1, A2, and print on the printing target surface onto which the product has been sprayed. In other words, upstream of the print head device 24 that prints on one printing target surface of the tablet T, the air outlet 101 of the plasma generator 100A that sprays the product onto that printing target surface is positioned. Furthermore, upstream of the print head device 34 that prints on the other printing target surface of the tablet T, the air outlet 101 of the plasma generator 100B that sprays the product onto that printing target surface is positioned.

The aforementioned imaging devices 23 and 33 are positioned downstream of the air outlet 101 in the conveying directions A1 and A2, and capture images of the printing surface onto which the product is sprayed. In this embodiment, the air outlet 101 is positioned between the detection devices 22 and 32 and the imaging devices 23 and 33 in the conveying directions A1 and A2.

Furthermore, as shown in Figure 2, the air outlet 101 is located opposite the suction holes 21g and 31g. For example, the air outlet 101 is located directly above the suction holes 21g and 31g, and the distance from the air outlet 101 to the tablets T being sucked into and transported by the suction holes 21g and 31g is approximately 10 mm.

In this embodiment, the suction holes 21g, 31g are each arranged in two rows. Therefore, in each of the first printing device 20 and the second printing device 30, two plasma generators 100 are arranged side by side in a direction perpendicular to the conveyance directions A1, A2, and two air outlets 101 face the two rows of suction holes 21g, 31g.

More specifically, as shown in FIG. 3, the plasma generator 100 has a body 110, a gas supply unit 120, a first electrode 140, a second electrode 150, and a power supply 160. Note that FIG. 3 shows a perspective view of the body 110. The body 110 is a component through which a process gas flows. The body 110 is a tubular component, and serves as a discharge tube in which an electric discharge occurs to generate plasma in the process gas. The body 110 is made of, for example, glass or alumina. The space inside the tubular body 110 forms a gas flow path 111. Note that in this embodiment, the body 110 is arranged so that its axial direction is vertical.

The plasma region Z, where plasma is generated, is the region where the process gas is ionized by the discharge, generating products such as ions, electrons, and radicals. Radicals here refer to molecules or atoms with unpaired electrons. In this way, the plasma region Z is the region that serves as the source of products.

The body 110 has a discharge section 112 that discharges the product generated in the plasma region Z for supply to a tablet T outside the body 110. In this embodiment, the discharge section 112 is a portion of the tubular body 110 with a reduced diameter at one end.

The discharge section 112 includes a nozzle 112a. The nozzle 112a is a cylindrical portion of the reduced-diameter portion of the body 110 that extends further axially and has an outlet 101 at its tip. One or both of the discharge section 112 and the nozzle 112a may be configured to be continuous with the body 110, or may be configured to be detachable and replaceable from the body 110. In the following description, the end of the body 110 where the discharge section 112 is provided will be referred to as the gas discharge side. Note that the body 110 has a process gas inlet 113 on the side opposite the discharge section 112.

The gas supply unit 120 is a device that supplies process gas to the gas flow path 111 inside the body 110. The process gas may be any gas that generates plasma through discharge. For example, rare gases such as He and Ar are used.

The gas supply unit 120 has a gas source 121, a regulator 122, and an opening/closing unit 123. The gas source 121 is a cylinder that stores process gas. The regulator 122 is a device that adjusts the flow rate of gas from the gas source 121. The regulator 122 is composed of a mass flow meter that measures the flow rate of the fluid and a mass flow controller (MFC) that has a solenoid valve that controls the flow rate. The opening/closing unit is a valve that opens and closes the flow path of the process gas.

The gas source 121 is connected to the adjustment unit 122 and the opening/closing unit 123 by piping, which is connected to the inlet 113 of the body 110. In other words, the process gas from the gas source 121 is introduced into the body 110 and becomes a gas flow. The introduction position of this process gas is opposite the gas discharge side of the body 110. The end side of the body 110 closest to the introduction position is called the gas introduction side. The gas introduction side of the body 110 is hermetically sealed.

When a voltage is applied to the first electrode 140 and the second electrode 150, plasma is generated in the process gas in the gas flow path 111. In other words, when a voltage is applied, the first electrode 140 and the second electrode 150 generate a discharge in the gas flow path 111, ionizing the process gas. The first electrode 140 is a rod-shaped conductive member that is inserted from the gas inlet end of the body 110 and extends into the gas flow path. The first electrode 140 is made of, for example, tungsten. The second electrode 150 is a ring-shaped conductive member that is provided along the outer periphery of the body 110. The second electrode 150 is made of, for example, Ni-plated SUS.

The power supply 160 applies a voltage to the first electrode 140 and the second electrode 150. For example, a high-frequency power supply for plasma generation is used as the power supply 160. In this embodiment, the second electrode 150 is the grounded side. In other words, the first electrode 140 is the main electrode, and the second electrode 150 surrounds the body 110 with the same ground potential and functions as a guard electrode to prevent leakage current.

As shown in FIG. 1, the control device 50 includes an image processing unit 51, a print processing unit 52, an inspection processing unit 53, a plasma control unit 54, and a memory unit 55. The image processing unit 51 processes images. The print processing unit 52 performs printing-related processing. The inspection processing unit 53 performs inspection-related processing. The plasma control unit 54 performs processing related to controlling the plasma generation device 100. The memory unit 55 stores various information such as processing information and various programs. The control device 50 controls the supply device 10, the alignment and conveying device 11, the first printing device 20, the second printing device 30, the recovery device 40, and the plasma generation device 100, and also receives position information of the tablets T transmitted from the individual detection devices 22, 32 of the first printing device 20 and the second printing device 30, and images transmitted from the individual imaging devices 23, 25, 33, 35 of the first printing device 20 and the second printing device 30.

The control device 50 also controls the gas supply unit 120 and the power supply 160. That is, the control device 50 starts and stops the supply of process gas by controlling the opening/closing unit 123, controls the flow rate of the process gas per unit time by controlling the adjustment unit 122, and controls the electric field strength in the plasma by adjusting the voltage applied by the power supply 160.

[Printing process]
Next, the printing process performed by the tablet printing device 1 will be described.

First, various information such as print data required for printing is stored in the memory unit 55 of the control device 50. Then, when a large number of tablets T to be printed are placed into the hopper 10a of the supply device 10, the tablets T flow from the hopper 10a into the duct 10b. The tablets T that flow into the duct 10b begin to be sequentially supplied to the alignment feeder 13 by the vibrating feeder 10c, and are arranged in two rows by the alignment feeder 13 as they move. The tablets T moving in these two rows are sequentially supplied to the conveyor belt 21a of the first printing device 20 by the transfer feeder 14. The conveyor belt 21a rotates in the conveying direction A1 due to 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 arranged in two rows on the conveyor belt 21a and transported at a predetermined speed. The conveyor belt 31a also rotates in the conveying direction A2 due to the rotation of the drive pulley 31b and each driven pulley 31c driven by the motor 31d.

In the first printing device 20, the tablet T on the aforementioned 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 55 and used in post-processing.

In the gas supply unit 120 of the plasma generator 100, the opening/closing unit 123 is opened in advance, and the process gas from the gas source 121 is introduced into the body 110 from the introduction position. Then, a voltage is applied to the first electrode 140 and the second electrode 150 by the power supply 160. This causes a discharge in the gas flow path within the body 110, ionizing the process gas. In other words, plasma is ignited.

In the plasma region Z where this plasma is generated, products such as ions, electrons, and radicals are generated by reaction with the atmosphere. For example, products such as OH radicals are generated, and these products are blown together with the gas flow from the blow-out port 101 toward the suction holes 21g in the conveyor belt 21a.

When a tablet T on the conveyor belt 21a passes under the outlet 101 after being detected by the detector 22, the product contained in the gas flow from the outlet 101 is sprayed onto one of the printing surfaces of the tablet T. In addition, the product is sucked in through the suction holes 21g between the tablets T.

Next, the tablets T on the conveyor belt 21a are imaged by the first imaging device 23 at a timing based on the position information of the tablets T described above, and the imaged images are transmitted to the control device 50. Based on the individual images transmitted from the first imaging device 23, positional deviation information of the tablets T (for example, the positional deviation of the tablets T in the X, Y, and θ directions in FIG. 3) is generated by the image processing unit 51 and stored in the memory unit 55. Based on this positional deviation information of the tablets T, the printing conditions for the tablets T (such as the ink ejection position and ejection timing) are set by the print processing unit 52 and stored in the memory unit 55.

Next, each tablet T on the conveyor belt 21a is printed by the print head device 24 based on the printing conditions described above, at a timing based on the position information of the tablet T described above, i.e., when the tablet T arrives below the print head device 24. In each print head 24a of the print head device 24, ink is ejected appropriately from each nozzle 24b, and identification information such as letters (e.g., alphabets, katakana, numbers) or marks (e.g., symbols, figures) is printed on the top surface of the tablet T.

The tablets T with the printed identification information are imaged by the second imaging device 25 at a timing based on the position information of the tablets T described above, and the captured images are sent to the control device 50. Based on the individual images sent from the second imaging device 25, printing position information indicating the printing position of the printing pattern for each tablet T is generated by the image processing unit 51 and stored in the memory unit 55. Based on the printing position information, the inspection processing unit 53 determines whether the printing on each tablet T is acceptable, and printing result information indicating the result of the printing for each tablet T is stored in the memory unit 55. For example, it is determined whether the printing pattern is printed in a predetermined position on the tablet T.

After inspection, the tablet T is transported along the conveyor belt 21a and passes above the drying device 26. 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 it, and the tablet T with dried ink is transported along the conveyor belt 21a and positioned near the end of the conveyor belt 21a on the driven pulley 21c side. At this position, the suction effect on the tablet T ceases to act, and the tablet T is released from its position 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, printing and inspection processes, including the spraying of atmospheric pressure plasma products, are carried out in the same manner as described above. After inspection, the tablets T are transported along the conveyor belt 31a and pass above the drying device 36. The tablets T, whose ink has dried, then reach the defective product collection device 41. At this position, defective tablets T fall from the underside of the conveyor belt 31a due to the gas spray from the spray nozzle 41a, and are collected by the storage device 41b. Meanwhile, non-defective tablets T pass through the defective product collection device 41 and reach the non-defective product collection device 42. At this position, the suction action on the tablets T ceases, and non-defective tablets T fall from the underside of the conveyor belt 31a due to the gas spray from the gas blowing section 42a, and are collected by the storage device 42b.

[Experimental Results]
Next, experimental results of the printing state depending on whether or not the product was sprayed by the plasma generator 100 will be described with reference to FIGS. 4 and 5. FIG. 4 is a comparative example in which the letters "SAMPLE" were printed without spraying. FIG. 5 is an example in which the letters "SAMPLE" were printed in the same pattern as FIG. 4 after spraying. FIGS. 4(A) and 5(A) are images of the entire printing surface of each tablet, and FIGS. 4(B) and 5(B) are enlarged images of the printed letter portion. In this experiment, He was used as the process gas, and after spraying at a gas flow rate of 1 L/min and a spraying time of 1 min, printing was performed using an inkjet print head under the same ejection conditions.

As shown in Figures 4(A) and (B), in the comparative example where no spraying was performed, there are a large number of gaps and cracks in the lines that make up the characters. On the other hand, as shown in Figures 5(A) and (B), in the example where spraying was performed, there are fewer gaps and cracks in the lines that make up the characters. Furthermore, when comparing Figures 4(A) and 5(A), it can be seen that in Figure 5(A), there are fewer gaps and cracks in the lines that make up the characters, making the characters appear darker and more clearly visible.

[effect]
(1) The tablet printing apparatus 1 of this embodiment as described above includes conveying devices 21, 31 that convey tablets T, a plasma generating device 100 that sprays atmospheric pressure plasma products from an outlet 101 onto the printing surface of the tablet T, and print head devices 24, 34 that are positioned downstream of the outlet 101 in the conveying direction A1, A2 of the tablet T and print on the printing surface onto which the products have been sprayed.

The inventors of the present application have confirmed that spraying atmospheric pressure plasma products onto the printing surface of tablets T before printing increases the affinity of the printing surface with the ink and reduces ink repulsion. This is presumably because organic matter on the printing surface is removed and cleaned, and OH radicals generate OH groups, making the surface hydrophilic. This can prevent printing defects such as lines being thinner than desired or broken lines, for example, when the printed pattern includes characters. This can therefore improve the appearance of printed tablets T.

In addition, the increased affinity of the ink with the printing surface allows the ink to wet and spread more than when the same amount of ink is applied to tablets T that have not been sprayed with atmospheric pressure plasma products, resulting in a larger surface area of the applied ink. Alternatively, it is possible to print the desired area even with a small amount of ink. As a result, the applied ink can dry more quickly compared to tablets T that have not been sprayed with the product, and it is possible to prevent print transfer to tablets T or the transport path P due to contact between tablets T or the tablets T being transported upside down. This can therefore prevent a decrease in print quality and the occurrence of equipment contamination.

Furthermore, since there is no longer a need to increase the viscosity of the ink to ensure fixation, the viscosity of the ink used can be reduced. Lowering the viscosity of the ink improves the ejection of ink from the print head devices 24 and 34, thereby reducing printing defects.

(2) The conveying devices 21, 31 have conveying belts 21a, 31a that convey tablets T sucked into the suction holes 21g, 31g by negative pressure, and the blow-out port 101 is located opposite the suction holes 21g, 31g.

As a result, tablets T are sucked into suction holes 21g and 31g and positioned, increasing the likelihood that the product will be sprayed onto the location of tablets T. Furthermore, the product generated by plasma generator 100 contains ozone, and inhaling air containing large amounts of ozone is harmful to the human body. In this embodiment, because the suction holes 21g and 31g face each other, gas sprayed between tablets T and gas after being sprayed onto tablets T is quickly exhausted from suction holes 21g and 31g. This prevents ozone from diffusing, and also prevents the adverse effects of ozone on workers.

Furthermore, because the tablet T is positioned by being sucked into the suction holes 21g and 31g, the area where the gas is sprayed is near the center of the tablet T, and the entire printing surface is sprayed. This also makes it less likely for the tablet T to shift out of position than if the gas flow were to be sprayed from a biased position.

(3) The printer has imaging devices 23 and 33, which are positioned downstream of the outlet 101 in the conveying direction A1 and A2 of the tablets T and which capture images of the printing target surface onto which the product is sprayed before printing by the print head devices 24 and 34.

This prevents misalignment caused by spraying after imaging by the imaging devices 23, 33, resulting in discrepancies between the imaging results and the printing conditions. Even if misalignment occurs due to spraying, the misalignment can be detected by subsequent imaging by the imaging devices 23, 33 and reflected in the printing conditions used by the print head devices 24, 34, thereby maintaining print quality.

(4) The process gas supplied to the plasma generator 100 is He or Ar. The temperature of the gas sprayed from the outlet 101 onto the printing surface of the tablet T depends on the type of process gas. Here, when He or Ar is used as the process gas, the temperature of the sprayed gas can be kept below 30°C, preventing the wax and sugar on the surface of the sugar-coated tablet from melting.

[Modification]
In the above-described embodiment, there is one blow-out outlet 101 in the direction along the conveying path P of the tablet T. However, multiple blow-out outlets 101 may be arranged in the direction along the conveying path P. For example, as shown in Figures 6(A) and 6(B), multiple plasma generators 100 may be arranged side by side at a position where the blow-out outlet 101 faces the suction holes 21g and 31g. This ensures that the product is sprayed onto the printing surface of the tablet T for a long time, even if the conveying speed of the tablet T is fast and the time it takes to pass the position facing the blow-out outlet 101 is short.

The plasma generator 100 may have a configuration in which the pipe extending from the discharge section 112 branches off, with the ends of the branches forming multiple outlets 101. Such multiple outlets 101 may be arranged in two rows on the conveying path P. Also, by arranging the multiple outlets 101 in a direction parallel to the conveying path P, the time for the product to be sprayed onto the printing surface of the tablet T can be extended.

Furthermore, the air outlet 101 of the plasma generator 100 may be shaped to extend in the direction along the conveying path P. For example, as shown in Figures 7(A) and (B), a slit-shaped air outlet 101 is arranged so that its longitudinal direction is along the conveying path P. In this case, too, it is possible to ensure a long time for the product to contact the printing surface of the tablet T. Note that the length of the air outlet 101 along the conveying path P need only be a length that includes multiple tablets T, and the length perpendicular to the conveying path P may be longer or shorter than the length along the conveying path P. For example, the air outlet 101 may be rectangular.

The supply device 10 may also be provided with an air outlet 101. For example, as shown in Figure 8, multiple plasma generators 100 are arranged in the supply device 10 so that the air outlets 101 face both printing surfaces of the tablets T. In this embodiment, the bottom surface of the vibrating feeder 10c is formed from a punched plate with multiple through holes 10d.

In other words, multiple plasma generators 100 are arranged in a row in the conveying direction of the tablets T above the vibrating feeder 10c, with the blowing outlets 101 facing the through holes 10d. Furthermore, multiple through holes 10d are formed in the underside of the vibrating feeder 10c. Multiple plasma generators 100 are arranged in a row in the conveying direction of the tablets T so that the product is sprayed from the underside of the vibrating feeder 10c through each through hole 10d onto the other printing surface of the tablets T.

Here, a large number of tablets T are placed into the hopper 10a, but not all of the placed tablets T immediately pass through the duct 10b and the vibrating feeder 10c and are supplied to the aligning and conveying device 11. Although shown simply in Figure 8, a large number of tablets T temporarily remain in the hopper 10a, duct 10b, and vibrating feeder 10c.

In this way, the product from the plasma generator 100 is sprayed onto one printing surface of the tablets T lined up in the vibrating feeder 10c, and also onto the other printing surface. This allows both printing surfaces of each tablet T in the vibrating feeder 10c to be treated so that the ink can be more easily fixed. Therefore, compared to spraying onto tablets T while they are being transported along the transport path P, the time they are exposed to the product can be longer, and both the top and bottom printing surfaces can be treated simultaneously. As mentioned above, the piping extending from the discharge section 112 of the plasma generator 100 may branch out, with the ends forming multiple outlets 101, each directed toward the top and bottom of the tablets T in the vibrating feeder 10c.

In addition, by replacing the plasma generator 100 installed in the vibrating feeder 10c with a spraying device using a tube or nozzle that sprays air or an inert gas, or by replacing the unit equipped with the plasma generator 100 with a unit equipped with the above-mentioned spraying device, it is possible to dry the tablets or remove powder from the surface of the uncoated tablets. In other words, the feeder 10 can be used as a place for powder removal, drying, and plasma treatment. This allows for simplification and space-saving of the device while accommodating a variety of tablet types.

In addition, while the above explanation exemplifies conveying tablets T in two rows, this is not limited to this; the number of rows may be one, three, four or more, and the number of conveying paths and the number of conveying belts 13a, 21a, 31a are not particularly limited. The blow-out port 101 may be positioned according to these aspects. Furthermore, the shapes of the suction holes 13f, 21g, 31g of the conveying belts 13a, 21a, 31a are not particularly limited.

In addition, while the above description exemplifies a print head 24a being provided for each transport path for tablets T, this is not limited to this; for example, one print head 24a may be used to print on two or more rows of tablets T.

In addition, in the above explanation, a print head with nozzles 24b arranged in a single row was used as an example of the inkjet print head 24a, but this is not limited to this. For example, a print head with nozzles 24b arranged in multiple rows may also be used. Furthermore, multiple print heads 24a may also be arranged in the transport direction A1.

In addition, in the above explanation, inkjet-type print head devices were used as examples of print head devices 24 and 34, but this is not limited to this. For example, transfer-type print head devices using transfer rolls or transfer pads can also be used. In this case, too, the fixation of the ink can be improved.

Furthermore, since printing can be performed after spraying the product onto the printing surface of the tablet T, the plasma generating device 100 may be placed on the alignment and conveying device 11. 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 on 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 on only one side of the tablet T.

Tablets T, whose printing surface has previously been sprayed with a product produced by atmospheric pressure plasma in a process other than the process using the tablet printing apparatus 1, may be fed into the tablet printing apparatus 1. In other words, when a product is sprayed onto the printing surface of tablets T using atmospheric pressure plasma, the effect of the surface treatment lasts, so a method of producing tablets T by spraying the product outside the tablet printing apparatus 1 and then printing it onto the printing surface using the tablet printing apparatus 1 is also an aspect of the present invention.

The aforementioned tablets can be any that can be sprayed with atmospheric pressure plasma products to enhance the affinity of the ink on the printing surface, and can include tablets used for pharmaceutical, food and beverage, cleaning, industrial, or aromatic purposes. Tablets can also be plain tablets (plain tablets), sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multi-layer tablets, and dry-coated tablets, and can also include various types of capsule tablets, such as hard capsules and soft capsules.

Furthermore, tablets come in a variety of shapes, including disks, lenses, triangles, ellipses, and rounded rectangles. In the case of shapes with both longitudinal and lateral directions, such as ellipses and rounded rectangles, when tablet T is rounded rectangular, as shown in Figure 9, the suction of suction holes 21g and 31g transports tablet T in the longitudinal direction along the arrangement direction of suction holes 21g and 31g. Therefore, if air outlet 101 is provided opposite suction holes 21g and 31g, it can be sprayed onto the entire elongated surface without moving away from the printing surface.

Furthermore, if the tablets to be printed are for medical or edible use, edible ink is suitable. This edible ink may be any of synthetic pigment ink, natural pigment ink, dye ink, and pigment ink.

Other Embodiments
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 spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

1 Tablet printing apparatus 10 Supply device 10a Hopper 10b Duct 10c Vibration feeder 10d Through hole 13 Alignment feeder 13a Conveyor belt 13f Suction hole 14 Transfer feeder 20 First printing apparatus 21 Conveyor device 21a Conveyor belt 21b Drive pulley 21c Driven pulley 21d Motor 21e Position detector 21f Suction chamber 21g Suction hole 22 Detection device 22a Detection unit 23 First imaging device 23a Imaging unit 24 Print head device 24a Print head 24b Nozzle 25 Second imaging device 25a Imaging unit 26 Drying apparatus 30 Second printing apparatus 31 Second conveying apparatus 31a Conveyor belt 31b Drive pulley 31c Driven pulley 31d Motor 31e Position detector 31f Suction chamber 31g Suction hole 32 Detection device 33 First imaging device 34 Print head device 35 Second imaging device 36 Drying device 40 Recovery device 41 Defective product recovery device 41a Spray nozzle 41b Storage device 42 Non-defective product recovery device 42a Gas blowing section 42b Storage device 50 Control device 51 Image processing section 52 Print processing section 53 Inspection processing section 54 Plasma control section 55 Memory section 100, 100A, 100B Plasma generating device 101 Blowing outlet 110 Body section 111 Gas flow path 112 Discharge section 112a Nozzle 113 Inlet 120 Gas supply section 121 Gas source 122 Adjustment section 123 Opening/closing section 140 First electrode 150 Second electrode 160 Power source

Claims (5)

a conveying device that conveys a plurality of coated tablets along a conveying path while suction-holding one side of the tablets with suction holes and conveys the tablets along the conveying path while suction-holding the other side of the tablets with suction holes;
a first plasma generator that blows a gas flow containing a product of atmospheric pressure plasma from a first blowing port onto the other surface of the tablet that is being conveyed while suction-holding the one surface;
a first inkjet print head device that is disposed downstream of the first air outlet in the tablet conveying direction and that prints on the other side of the tablet conveyed by the conveying device onto which the gas flow is blown;
a second plasma generating device that is disposed downstream of the first print head device in the tablet conveying direction and that blows a gas flow containing a product of atmospheric pressure plasma from a second blowing port onto one side of the tablet that is conveyed while suction-holding the other side; and
a second inkjet print head device that is disposed downstream of the second outlet in the conveying direction and that is capable of printing on the one side of the tablet conveyed by the conveying device;
and
the first air outlet is provided at a position facing the other surface of the tablet sucked and held by the suction hole,
the second outlet is provided at a position facing the one surface of the tablet sucked and held by the suction hole,
A tablet printing apparatus characterized in that the suction hole located between the tablets transported by the conveying device sucks in the products contained in the gas flow blown from the first outlet and the second outlet . The tablet printing device according to claim 1 , wherein a plurality of the first air outlets and a plurality of the second air outlets are arranged in the direction along the conveying direction of the tablets. The tablet printing device described in claim 1, characterized in that the first and second air outlets are shaped to extend in the direction along the conveying direction of the tablets. a first imaging device that is disposed downstream of the first air outlet in the tablet conveying direction and that images the other surface of the tablet onto which the gas flow is blown before printing by the first print head device;
a second imaging device that is disposed downstream of the second air outlet in the tablet conveying direction and that images the one surface of the tablet onto which the gas flow is blown before printing by the second print head device;
3. The tablet printing device according to claim 1, further comprising: A plurality of suction holes are provided in the conveyor belt to suction-hold one side of the plurality of coated tablets and convey them.
A gas flow containing a product of atmospheric pressure plasma is sprayed onto the tablet from a first outlet provided at a position facing the other surface of the tablet, and then
a step of printing on the other surface onto which the gas flow is sprayed using a first print head device of an inkjet type;
The other surface of the tablet printed by the first print head device is suction-held by the suction holes and conveyed;
a gas flow containing a product of atmospheric pressure plasma is sprayed from a second nozzle provided at a position facing the one surface of the tablet printed by the first print head device, and then
printing, by a second print head device of an inkjet type, on the one surface onto which the gas flow is blown from the second blowout port;
A tablet manufacturing method characterized in that the suction hole located between the tablets transported by the conveying belt sucks in the product contained in the gas flow blown from the first blowing outlet and the second blowing outlet .