JP7507272B2 - 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.

Currently, tablet printing devices that use inkjet heads to print various information such as identification information on tablets are being developed. Among these tablet printing devices, there are devices that use inkjet heads to print on tablets that are sucked and held in suction holes. In such devices, at the back of the area where printing is performed by the inkjet head, a camera, detection sensor, a control board that controls the inkjet head, etc., a blower used to suck and hold the tablets, a motor used to transport the tablets, etc. are all provided together.

The control board, blower, motor, etc. are heat sources, and the air heated here is pulled by the suction used to hold the tablets and flows into the suction hole side. Because the inkjet head is located above the suction hole, the above-mentioned air flow causes the temperature near the inkjet head to rise. When the temperature near the inkjet head rises, the viscosity of the ink in the inkjet head decreases, making it impossible to eject a fixed amount of ink, or the area near the nozzle dries out, causing the ink to stick to the nozzle. This can cause ejection problems and printing defects. Alternatively, the rise in temperature near the inkjet head can make the ink in the inkjet head more susceptible to deterioration.

JP 2013-122401 A

The problem that this invention aims to solve is to provide a tablet printing device and tablet printing method that can reduce the occurrence of printing defects and ink deterioration.

A tablet printing device according to an embodiment of the present invention comprises a conveying unit provided in a first region which conveys a tablet by suction and holding it in a suction hole, an inkjet head provided in the first region which prints on the tablet conveyed by the conveying unit, a heat source provided in a second region connected to the first region and arranged to be aligned with the first region in a direction perpendicular to the conveying direction of the tablet conveyed by the conveying unit, a cooling unit which supplies gas to the first region at a temperature lower than that of the second region, and a housing which surrounds the first region and the second region, and the cooling unit is arranged to blow the gas so as to hit the inkjet head, avoiding the surface of the inkjet head facing the conveying unit .

A tablet printing method according to an embodiment of the present invention includes a conveying unit provided in a first region within a housing , which conveys a tablet by suction and holding it in a suction hole; an inkjet head provided in the first region printing on the tablet conveyed by the conveying unit; and, in a state in which a heat source is present in a second region connected to the first region and which is provided within the housing so as to be aligned with the first region in a direction perpendicular to the conveying direction of the tablet conveyed by the conveying unit, a cooling unit supplies gas having a temperature lower than that of the second region to the inkjet head, avoiding the surface of the inkjet head facing the conveying unit .

According to an embodiment of the present invention, it is possible to reduce the occurrence of printing defects and ink deterioration.

FIG. 1 is a diagram illustrating an example of a schematic configuration of a tablet printing apparatus according to an embodiment. FIG. 1 is a diagram illustrating an example of a schematic configuration of a printing apparatus according to an embodiment. 3 is a cross-sectional view taken along line X1-X1 in FIG. 2, illustrating the cooling function of the tablet printing apparatus according to the embodiment. FIG. 3 is a diagram showing an example of a housing of the tablet printing device according to the embodiment, as viewed in the direction of the arrow Y1 in FIG. 2 . FIG. 5A to 5C are diagrams illustrating an example of a partition member according to the embodiment. 5A to 5C are diagrams illustrating an example of a partition member according to the embodiment. 5A to 5C are diagrams illustrating an example of a partition member according to the embodiment. FIG. 2 is a diagram illustrating an example of a control device according to the embodiment. 5A and 5B are diagrams for explaining a retraction function of the inkjet head according to the embodiment. 5 is a flowchart showing an example of a flow of a printing process according to the embodiment.

<Embodiment>
An embodiment will be described with reference to the drawings.

(Example of configuration of tablet printing device)
An example of the configuration of a tablet printing device 1 according to an embodiment will be described with reference to FIGS. 1 and 2. FIG.

As shown in FIG. 1, the tablet printing device 1 according to the embodiment includes a supply device 10, a printing device 20, a collection device 30, and a control device 40.

The supply device 10 has a hopper 11, an alignment feeder 12, and a transfer feeder 13. The supply device 10 is positioned at one end of the printing device 20 and is configured to be able to supply tablets T, which are printing objects, to the printing device 20. The hopper 11 stores a large number of tablets T and sequentially supplies the stored tablets T to the alignment feeder 12. The alignment feeder 12 aligns the supplied tablets T in a line and transports them in a conveying direction A1 (clockwise direction) toward the transfer feeder 13. The transfer feeder 13 sequentially sucks in and holds each tablet T lined up in a line on the alignment feeder 12 from the upper side of the tablet T, transports each held tablet T in a line to the printing device 20, and delivers it to the printing device 20. As the alignment feeder 12, for example, a belt conveying mechanism or a vibration feeder is used. As the transfer feeder 13, for example, a belt conveying mechanism is used. The belt conveying mechanism of this delivery feeder 13 rotates in the conveying direction A2 (counterclockwise). The supply device 10 is electrically connected to the control device 40, and its drive is controlled by the control device 40.

The printing device 20 includes a transport unit 21, a detection unit 22, a first imaging unit 23, an inkjet head 24, a second imaging unit 25, a movement mechanism 26, a maintenance unit 27, and a drying unit 28.

As shown in FIG. 2, for example, two of each of the detection unit 22, first imaging unit 23, inkjet head 24, and second imaging unit 25 are provided, but the number is not particularly limited and is set according to the number of transport paths for the tablets T. Note that the configuration of each detection unit 22, the configuration of each first imaging unit 23, the configuration of each inkjet head 24, and the configuration of each second imaging unit 25 are all the same, so only one of each will be described below.

Returning to FIG. 1, the conveying section 21 has a conveying belt 21a, a driving pulley 21b, a plurality of driven pulleys 21c, a motor 21d, a position detector 21e, and a suction chamber 21f. The conveying belt 21a is an endless belt and is stretched across the driving pulley 21b and each of the driven pulleys 21c. The driving pulley 21b and each of the driven pulleys 21c are rotatably mounted on the device body (not shown), and the driving pulley 21b is connected to the motor 21d. The motor 21d is electrically connected to the control device 40, and its drive is controlled by the control device 40. The position detector 21e is a device such as an encoder and is attached to the motor 21d. This position detector 21e is electrically connected to the control device 40, and transmits a detection signal to the control device 40. The conveying unit 21 moves the conveying belt 21a 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).

As shown in FIG. 2, a plurality of circular suction holes 21g are formed in the conveyor belt 21a. Each of these suction holes 21g is a through hole that adsorbs the tablet T, and is arranged in two rows along the conveyor direction A1 to form two conveyor paths extending in parallel. Each suction hole 21g is connected to the inside of the suction chamber 21f (see FIG. 1) through a suction path (not shown) formed in the suction chamber 21f, and suction force can be obtained by the suction chamber 21f. A blower is connected to the suction chamber 21f through a suction pipe (not shown), and the inside of the suction chamber 21f is depressurized by the operation of the blower. The suction pipe is connected to approximately the center of the side surface (plane parallel to the conveyor direction A1) of the suction chamber 21f. The blower is also electrically connected to the control device 40, and its drive is controlled by the control device 40. When the inside of the suction chamber 21f is depressurized, the tablet T placed on each suction hole 21g of the conveyor belt 21a is sucked by the suction hole 21g and held on the conveyor belt 21a.

The detection unit 22 is positioned downstream in the conveying direction A1 from the position where the supply device 10 is provided, and is provided above the conveying path formed by the suction hole 21g. This detection unit 22 detects the tablet T that has reached the detection position directly below the detection unit 22 (arrival of tablet T), that is, the position of the tablet T on the conveying belt 21a in the X direction (see FIG. 2) by projecting and receiving laser light. The detection unit 22 also detects the height of the tablet T on the conveying belt 21a. For example, a displacement sensor is used as the detection unit 22. Also, various types of laser sensors, such as a reflective laser sensor, are used as the displacement sensor. The detection unit 22 is electrically connected to the control device 40, and transmits a detection signal to the control device 40.

The first imaging unit 23 is positioned downstream in the conveying direction A1 from the position where the detection unit 22 is provided, and is provided above the conveying path formed by the suction hole 21g. Based on the position information of the tablet T in the X direction detected by the detection unit 22, the first imaging unit 23 performs imaging at the first imaging timing when the tablet T reaches the imaging position directly below the first imaging unit 23, obtains a first image including the upper surface of the tablet T, and transmits the obtained first image to the control device 40. The first image is used to detect the positions of the tablet T in the X direction, Y direction, and θ direction (see FIG. 2), and to detect the presence or absence of damage or foreign matter attached to the tablet T (for example, cracks, chips, dirt, etc.). As the first imaging unit 23, various cameras having imaging elements such as a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) are used. The first imaging unit 23 is electrically connected to the control device 40, and its drive is controlled by the control device 40. In addition, illumination for imaging is also provided as necessary.

Here, the positions of the tablet T in the X and Y directions are, for example, positions in the XY coordinate system relative to the center (reference position) of the imaging area of the first imaging unit 23. The position in the θ direction is, for example, a position indicating the degree of rotation of the tablet T in a horizontal plane along the XY plane of the imaging area of the first imaging unit 23. This position in the θ direction is detected when the tablet T has a shape with directionality, such as when the tablet T has a score line or is molded into an oval, elliptical, rectangular, or other shape. The X and Y directions are positions in the horizontal direction.

The first imaging unit 23 further includes a cover 23a (see FIG. 2). The cover 23a corresponds to the first cover and is a member for preventing foreign matter from adhering to the light receiving portion of the first imaging unit 23. The cover 23a is not in contact with the conveyor belt 21a and is provided so as to surround the first imaging unit 23. The lower end of the cover 23a is at the same height as the retracted position H3 of the inkjet head 24 described later (see FIG. 9). The lower end of the cover 23a does not necessarily have to be at the same height as the retracted position H3 of the inkjet head 24, as long as it is at a height that does not contact the tablet T. The cover 23a is formed of a metal such as stainless steel, for example.

The inkjet head 24 is positioned downstream in the transport direction A1 from the position where the first imaging unit 23 is provided, and is provided above the transport path formed by the suction holes 21g. The inkjet head 24 has a plurality of nozzles 24a (e.g., hundreds to thousands) (see FIG. 2), and is provided so that the direction in which the nozzles 24a are lined up (nozzle row) is perpendicular (one example of an intersection) to the transport direction A1 in a horizontal plane. The inkjet head 24 ejects ink individually from each nozzle 24a by the operation of a drive element for each nozzle 24a. As the inkjet head 24, various inkjet type print heads having drive elements such as piezoelectric elements, heat elements, or magnetostrictive elements are used. The inkjet head 24 is electrically connected to a control device 40, and its drive is controlled by the control device 40.

The second imaging unit 25 is positioned downstream in the conveying direction A1 from the position where the inkjet head 24 is provided, and is provided above the conveying path formed by the suction hole 21g. Based on the position information of the tablet T in the X direction detected by the detection unit 22, the second imaging unit 25 captures an image at the second imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 25, obtains a second image including the upper surface of the tablet T, and transmits the obtained second image to the control device 40. The second image is used to inspect the print pattern printed on the tablet T. As with the first imaging unit 23 described above, various cameras having imaging elements such as CCD and CMOS are used as the second imaging unit 25. The second imaging unit 25 is electrically connected to the control device 40, and its drive is controlled by the control device 40. Illumination for imaging is also provided as necessary.

The second imaging unit 25 further includes a cover 25a (see FIG. 2). The cover 25a corresponds to a second cover and is a member for preventing foreign matter from adhering to the light receiving portion of the second imaging unit 25. The cover 25a is not in contact with the conveyor belt 21a and is provided so as to surround the second imaging unit 25. The lower end of the cover 25a is at the same height as the retracted position H3 of the inkjet head 24 described later (see FIG. 9). The lower end of the cover 23a does not necessarily need to be at the same height as the retracted position H3 of the inkjet head 24, as long as it is at a height that does not contact the tablet T. The cover 25a is formed of a metal such as stainless steel.

The moving mechanism 26 moves each inkjet head 24 in the lifting direction (the up-down direction in FIG. 1). As shown in FIG. 2, the moving mechanism 26 has, for example, an arm 26a and an arm moving mechanism 26b. The arm 26a is a holding unit that holds each inkjet head 24. For example, the arm 26a holds each inkjet head 24 with the ejection surface facing the conveying surface of the conveying belt 21a. The conveying surface of the conveying belt 21a is the surface on which the tablet T is placed on the conveying belt 21a, and is the surface of the conveying belt 21a on the inkjet head 24 side. The ejection surface of the inkjet head 24 is the surface on which the nozzle 24a is formed on the inkjet head 24, and is the surface of the inkjet head 24 on the conveying belt 21a side. The arm moving mechanism 26b is a mechanism that holds the arm 26a and moves it in the lifting direction. The arm moving mechanism 26b is provided at a position adjacent to the side of the suction chamber 21f (a surface parallel to the conveying direction A1). For example, a linear guide mechanism is used as the arm movement mechanism 26b. The arm movement mechanism 26b is electrically connected to the control device 40, and its drive is controlled by the control device 40. This type of movement mechanism 26 can change the distance (separation distance) between the conveying surface of the conveyor belt 21a and the ejection surface of each inkjet head 24 by raising and lowering the arm 26a, i.e., each inkjet head 24, using the arm movement mechanism 26b.

In the present embodiment, the maximum raised position of the inkjet head 24 is the maintenance position H2, which will be described later. However, the maximum raised position of the inkjet head 24 is not limited to this. The maximum raised position of the inkjet head 24 may be a position higher than the maintenance position H2. In other words, the maximum raised position may be a height at which the vicinity of the nozzle of the inkjet head 24 is not dried by the cooling unit 61, which will be described later. However, the lower the maximum raised position of the inkjet head 24 is, the lower the ceiling height of the cover 53, which will be described later, can be. The lower the ceiling height of the cover 53 is, the smaller the volume of the space covered by the cover 53 is. Therefore, the cooling efficiency of the cooling unit 61, which will be described later, can be improved.

The maintenance unit 27 performs maintenance operations for each inkjet head 24. Examples of the maintenance operations include wiping operations and ink receiving operations. As shown in FIG. 2, the maintenance unit 27 has, for example, a wiping unit 27a and a receiving tray 27b. The wiping unit 27a is a cleaning unit that cleans the ejection surface of each inkjet head 24 by reciprocating the maintenance unit 27 in the Y direction (see FIG. 2). The receiving tray 27b is a receiving member that receives droplets ejected from each inkjet head 24. The maintenance unit 27 is provided at a position adjacent to the side surface (surface parallel to the conveying direction A1) of the suction chamber 21f, and is configured to be movable between the conveying surface of the conveyor belt 21a and the ejection surface of each inkjet head 24 by a moving mechanism (for example, a linear guide mechanism) (not shown). During maintenance, the distance between the conveying surface of the conveyor belt 21a and the ejection surface of each inkjet head 24 is widened by the moving mechanism 26 by a distance that allows the maintenance unit 27 to move between those surfaces and perform maintenance operations.

The drying unit 28 is disposed opposite the conveyor belt 21a, for example, below the conveyor unit 21. This drying unit 28 dries the ink applied to each tablet T on the conveyor belt 21a. As the drying unit 28, various types of dryers are used, such as a blower that dries with gas such as air, a heater that dries with radiant heat, or a blower that dries with warm or hot air using both gas and a heater. The drying unit 28 is electrically connected to the control device 40, and its operation is controlled by the control device 40.

The recovery device 30 is positioned downstream in the conveying direction A1 from the position where the drying section 28 is provided, and is provided below the conveying section 21. This recovery device 30 has a reusable product recovery section 31, a defective product recovery section 32, and a good product recovery section 33. The recovery device 30 recovers reusable tablets T by the reusable product recovery section 31, recovers defective tablets T by the defective product recovery section 32, and recovers good tablets T by the good product recovery section 33. For example, the reusable products are reusable tablets and non-printed tablets that are undamaged and have no foreign matter attached. In addition, the defective products are non-printed tablets with foreign matter attached, tablets that fail printing (printed tablets) that are undamaged and have no foreign matter attached, etc., and the good products are tablets that pass printing (printed tablets) that are undamaged and have no foreign matter attached. Note that the order of arrangement in the conveying direction A1 in the reusable product recovery section 31, the defective product recovery section 32, and the good product recovery section 33 is not limited to the order shown in FIG. 1, and may be changed as appropriate. The recovery device 30 is electrically connected to the control device 40, and its operation is controlled by the control device 40.

The reusable product collection section 31 has a spray nozzle 31a and a collection box 31b. The defective product collection section 32 has a spray nozzle 32a and a collection box 32b. The non-defective product collection section 33 has a spray nozzle 33a and a collection box 33b. These spray nozzles 31a, 32a, and 33a basically have the same structure, and each of the collection boxes 31b, 32b, and 33b also basically have the same structure. For this reason, the spray nozzle 31a and the collection box 31b will be described as representative.

The injection nozzle 31a and the collection box 31b are provided at positions facing each other across the conveying path where the suction holes 21g of the conveying belt 21a are lined up. The injection nozzle 31a is arranged in the suction chamber 21f, and for example, injects gas (e.g., air) toward the conveying belt 21a, causing the tablets T to fall from the conveying belt 21a. At this time, the gas injected from the injection nozzle 31a passes through the suction holes 21g of the conveying belt 21a and hits the tablets T. The injection nozzle 31a is electrically connected to the control device 40, and its drive is controlled by the control device 40. The collection box 31b is provided directly below the injection nozzle 31a and below the conveying unit 21. This collection box 31b receives and stores the tablets T that have fallen from the conveying belt 21a due to the gas injected from the injection nozzle 31a.

Here, the tablets T that have passed through the reusable product recovery section 31 and the defective product recovery section 32 are transported along with the movement of the conveyor belt 21a, and reach a position near the end of the conveyor belt 21a on the driven pulley 21c side. At this position, the suction effect on the tablets T ceases, but gas is sprayed onto the tablets T from above by the injection nozzle 33a, causing the tablets T to fall from the conveyor belt 21a. Therefore, by providing the injection nozzle 33a, it is possible to reliably cause the tablets T to fall from the conveyor belt 21a. The collection box 33b receives and stores the tablets T that have fallen from the conveyor belt 21a due to the gas sprayed from the injection nozzle 33a.

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

(Cooling function of tablet printing device)
Next, the cooling function of the tablet printing apparatus 1 will be described with reference to FIGS.

As shown in Figures 2 to 4, the tablet printing device 1 has a housing 51. This housing 51 houses each part of the tablet printing device 1. The parts include the supply device 10, the printing device 20, the recovery device 30, and the control device 40, but in the example of Figure 3, a cooling unit 61 and a heat source 62 are also shown, as well as the conveying unit 21, each inkjet head 24, the moving mechanism 26, and the maintenance unit 27.

The housing 51 has a door 52, a door 55, and a cover 53. The door 52 and the door 55 are attached to the housing 51 so as to be openable and closable. An opening 52a is formed in the door 52. The opening 52a is formed to a size in which the exterior of the cooling unit 61 fits, and further, so that when the door 52 is closed, the end of the cooling unit 61 on the door 52 side is inserted into the opening 52a. A gap member such as a packing may be provided in the opening 52a. The housing 51 has a holding portion 51a on the upper side of the inkjet head 24 and on the upper side of the heat source 62. The holding portion 51a is, for example, a planar plate that covers the upper sides of the inkjet head 24, the first imaging unit 23, and the second imaging unit 25. An input device 40a and an output device 40b, which will be described later, are housed above the holding portion 51a. The detection unit 22, the first imaging unit 23, the second imaging unit 25, and the like are housed below the holding portion 51a. Additionally, a partition member 54 is provided inside the housing 51 between the transport unit 21 and the heat source 62.

The partition member 54 is a wall for separating the first region R1 from the second region R2, and prevents the heat of the heat source 62 from flowing into the first region R1. The partition member 54 is formed of a metal plate such as stainless steel. The length of the partition member 54 in the X direction is the same as the length of the transport section 21 in the X direction. The upper end of the partition member 54 is connected to the ceiling of the housing 51, but does not necessarily need to be connected to the ceiling of the housing 51. A gap may be provided between the upper end of the partition member 54 and the ceiling of the housing 51. There is a cable connecting the first imaging section 23 or the second imaging section 25 to the control board. The partition member 54 is provided with a hole (not shown) through which the cable or the like can pass. In addition, as shown in FIG. 4 and FIG. 5, the partition member 54 is provided with an opening 54a. The opening 54a is an opening for connecting the moving mechanism 26 to the inkjet head 24. The opening 54a also serves as an opening through which the maintenance unit 27 moves between the first area R1 and the second area R2.

In this embodiment, the opening 54a is a notch. The outer shape of the opening 54a is T-shaped. For example, a part of the partition member 54 having a rectangular or quadrangular shape is cut out in a T-shape, and the T-shaped opening 54a is formed in a part of the partition member 54. Specifically, the opening 54a is formed by cutting downward in the Z direction from the upper end of the partition member 54. The length of the opening 54a in the X direction at the upper end side of the partition member 54 is the same as the length of the door 52. The length of the X direction at the part protruding below the opening 54a is the same as the length of the cover 53 in the X direction. The opening 54a is provided at a position where the maintenance unit 27 and the partition member 54 intersect. In other words, the upper end of the partition member 54 at the position where the protruding part of the opening 54a is provided is provided so as to be located at a height that allows the maintenance unit 27 to move between the first region R1 and the second region R2. The opening 54a is a T-shaped notch to avoid interference between the partition member 54 and the holding part 51a. In cases where the holding part 51a is not present, for example, the opening 54a may be a notch of a shape other than a T, or may be a hole of a rectangular, square, circular, or other shape.

The partition member 54 may be formed from a single plate as shown in FIG. 5, or may be formed by combining multiple plates 54b as shown in FIG. 6. In this case, a plate 54b may be present that covers the upper part of the holding portion 51a. Also, as shown in FIG. 7, the partition member 54 may be formed from multiple plates 54b and a frame 54c that can be attached to the housing 51. Note that multiple plates 54b may be attached to pillars or beams of the housing 51 instead of the frame 54c.

2 and 3, the cover 53 is a cover member that closes the space above the conveying section 21 from the door 52 side (front side). At least each inkjet head 24 is present in the space surrounded by the cover 53. The cover 53 is attached to the partition member 54 so as to cover a part of the opening 54a of the partition member 54, and is a cover that closes the space above the conveying section 21. In other words, the space surrounded by the cover 53 is connected to the opening 54a of the partition member 54. In this embodiment, the upper part of the opening 54a cannot be covered by the cover 53 because it is separated by the holding part 51a. However, if the cover 53 can cover the entire opening 54a, it may be covered. In short, it is sufficient that the cover 53 can cover the range into which the gas in the second region R2 flows toward the inkjet head 24.

The cover 53 has, for example, a main body 53b and a door part 53c. The main body 53b is a member that covers the space above the conveying part 21 and has a U-shaped outer shape when viewed from the front side with the opening of the U facing downward. The main body 53b is connected to the partition member 54 so as to cover part or all of the opening 54a of the partition member 54 with the opening of the U facing downward. Therefore, the main body 53b has two side surfaces perpendicular to the conveying direction A1 and a ceiling that connects these two side surfaces. The ceiling of the main body 53b is higher than the top of the inkjet head 24 at the maximum raised position. In addition, the ceiling of the main body 53b is located at a height within the range of the lifting stroke of the inkjet head 24 than the upper end of the inkjet head 24 at the maximum raised position. The main body 53b is provided so as to just fill the space between the cover 23a and the cover 25a.

The door section 53c is a door that can be opened and closed relative to the main body 53b. The door section 53c is, for example, box-shaped with one of the four sides missing. The door section 53c is attached to the end of the main body 53b opposite the partition member 54 side via a hinge (not shown) with the missing side facing the inkjet head 24. The door section 53c is also detachably provided on the cover 25a. Therefore, in this embodiment, the cover 53 corresponds to a third cover that is between the cover 23a and the cover 25a and covers the space above the transport section 21.

The door section 53c is attached to the cover 25a while the tablet printing device 1 is operating. When the inkjet head 24 is to be installed or removed, the door section 53c is removed from the cover 25a and moves to the cover 23a side via a hinge (not shown). Therefore, the inkjet head 24 can be installed or removed from the front side. This makes it easy to install and remove the inkjet head 24.

A ventilation section 53a is formed on the surface of the cover 53 facing the door 52 (surface parallel to the conveying direction A1). The upper part of the ventilation section 53a is at the same height as the ceiling of the main body 53b or at a position several centimeters lower. In addition, the ceiling of the main body 53b is at a position higher than the upper end of the inkjet head 24 at the maximum raised position by a height within the range of the lifting stroke of the inkjet head 24. For example, a mesh member such as a wire net or a punching member such as a punching plate is used as the ventilation section 53a. The ventilation section 53a is for supplying the outside air taken in by the cooling section 61 from the ventilation section 53a into the cover 53. The cooling section 61 is provided on the surface of the cover 53 facing the door 52 so as to close the ventilation section 53a. In addition, it is preferable that the lower end of the ventilation section 53a is higher in the height direction than the upper part of the inkjet head 24 at the maximum raised position. If the lower end of the ventilation section 53a is higher than the upper part of the inkjet head 24, the flow of the cooling gas is not impeded by the inkjet head 24. Therefore, the cooling gas from the cooling section 61 can easily flow to the second region R2. In this case, it goes without saying that the upper end of the ventilation section 53a is located above the lower end of the ventilation section 53a.

In the housing 51, there is a first region R1 and a second region R2 connected to the first region R1. The transport unit 21 and the inkjet heads 24 are provided in the first region R1, and the heat source 62 is provided in the second region R2. The moving mechanism 26 exists across the first region R1 and the second region R2, and the maintenance unit 27 has a standby position in the second region R2 and a maintenance position in the first region R1. The maintenance position of the maintenance unit 27 is a position where maintenance of the inkjet head 24 (purging, dummy ejection, wiping, etc.) is performed, and is a position below the inkjet head 24. The standby position of the maintenance unit 27 is a position of the maintenance unit 27 when maintenance of the inkjet head 24 is not performed, and is a predetermined position in the second region R2 as shown in FIG. 3. The maintenance unit 27 moves between the maintenance position and the standby position, that is, moves in the left-right direction of FIG. 3.

Here, the first region R1 is the region of the housing 51 closer to the door 52 than the partition member 54. The second region R2 is the region of the housing 51 closer to the heat source 62 than the partition member 54.

Each inkjet head 24 is moved in the elevation direction (up and down in FIG. 3) by the movement mechanism 26, and the movement range Ha of their ejection surfaces in the elevation direction is the range between a normal position H1 where each inkjet head 24 is normally located, and a maintenance position H2 where the maintenance unit 27 performs maintenance work on each inkjet head 24. The maintenance position H2 is a position where the maintenance unit 27 moves between the conveying surface of the conveyor belt 21a and the ejection surface of each inkjet head 24 to perform maintenance work.

The cooling unit 61 takes in outside air and sends it into the cover 53. The cooling unit 61 may be, for example, a cooling fan that creates an air flow, but is not limited to this. The cooling unit 61 may be capable of supplying gas at a temperature lower than that of the second region R2 to at least the first region R1, and may be, for example, a supply unit that supplies compressed gas through a tube or the like. The gas may be, for example, air or nitrogen.

The cooling unit 61 is also arranged to face the heat source 62 with the inkjet head 24 between them in a direction intersecting the X direction, which is the conveying direction A1 of the tablets T (for example, the Y direction, which is a perpendicular direction). Specifically, the cooling unit 61 is arranged on the end side in the direction in which the inkjet heads 24 are lined up (the Y direction). This is to ensure that the gas supplied by the cooling unit 61 hits all of the inkjet heads 24.

The cooling unit 61 blows out and supplies gas along a direction intersecting the conveying direction A1 of the tablet T in a horizontal plane (for example, the Y direction, which is a perpendicular direction perpendicular to the conveying direction A1). Since the gas is supplied toward the second region R2 on the heat source 62 side, it is possible to prevent air from flowing into the suction hole 21g from the second region R2 on the heat source 62 side. If the amount of air flowing into the suction hole 21g from the second region R2 is reduced by the gas supplied from the cooling unit 61, the temperature of the air sucked into the suction hole 21g will decrease, and the temperature of the first region R1 will also decrease. Note that the gas supply direction may be, for example, by providing the cooling unit 61 above the inkjet head 24, so that the gas may be supplied from above the inkjet head 24 downward. As long as the temperature of the air flowing into the suction hole 21g can be reduced, the gas supply direction is not particularly limited.

The lower end of the cooling unit 61 is arranged so that it is always higher than the ejection surface of each inkjet head 24 moving in the vertical direction, i.e., higher than the upper limit of the moving range Ha of the ejection surface of each inkjet head 24 in the vertical direction. In other words, the cooling unit 61 is arranged so that it blows out gas while avoiding the ejection surface of the inkjet head 24 that is moved by the moving mechanism 26.

Such a cooling unit 61 is electrically connected to the control device 40, and its operation is controlled by the control device 40. For example, the cooling unit 61 may be operated constantly when the device power is on, or may be operated for a predetermined time only, or may be stopped for a predetermined time only. In addition, since the diffusion of heat by the heat source 62 is weak for a predetermined time from the start of tablet printing (for example, a predetermined time for a predetermined number of tablets T to be printed), the cooling unit 61 may be operated after the predetermined time has elapsed. In addition, a cooling unit 161 is provided on the second region R2 side of the housing 51.

The cooling unit 161 takes in air within the second region R2 and expels it to the outside of the device. The cooling unit 161 is provided, for example, in a portion of the housing 51 that separates the outside of the device from the second region R2. For example, a cooling fan is used as the cooling unit 161. However, the cooling unit 161 is not limited to this. The cooling unit 161 may be a blower or a pump. When the cooling unit 161 is a blower or a pump, the cooling unit 161 is provided outside the device. The cooling unit 161 is connected to a portion of the housing 51 that contacts the second region R2 via piping.

The heat source 62 is a source that generates heat. For example, the heat source 62 is a heat source related to one or both of the conveying operation of the conveying unit 21 and the printing operation of the inkjet head 24. Examples of this heat source 62 include a control board such as the control device 40, a blower used to suck and hold the tablets T, and a motor used to convey the tablets T.

(Example of control device configuration)
Next, an example of the configuration of the control device 40 will be described with reference to FIG.

As shown in FIG. 8, the control device 40 has an image processing unit 41, a storage unit 42, and a control unit 43. An input device 40a and an output device 40b are connected to the control device 40. The input device 40a is realized, for example, by a switch, a touch panel, a keyboard, a mouse, etc. The output device 40b is realized, for example, by a display, a lamp, a meter, etc.

The image processing unit 41 captures the first image captured by the first imaging unit 23 and the second image captured by the second imaging unit 25, and processes the images using a known image processing technique. For example, the image processing unit 41 processes the first image obtained from the first imaging unit 23 to obtain the presence or absence of damage or foreign matter on the tablet T, and further obtains the positions of the tablet T in the X direction, Y direction, and θ direction. The image processing unit 41 also processes the second image obtained from the second imaging unit 25 to obtain the printing position, shape, and size of the printing pattern (e.g., letters or marks) printed on the tablet T. The image processing unit 41 transmits to the control unit 43 the acquired information on the presence or absence of damage or foreign matter on the tablet T, the acquired position information of each tablet T in the X direction, Y direction, and θ direction, and further the printing position information, shape information, and size information of the printing pattern on each tablet T.

The memory unit 42 stores processing information and various programs. For example, it is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The memory unit 42 stores print data related to printing, data on the movement speed of the conveyor belt 21a, etc. The print data includes information on printing patterns such as characters and marks.

The control unit 43 is, for example, a computer such as a CPU (Central Processing Unit), MCU (Micro Control Unit), or MPU (Micro Processing Unit), and controls each unit. For example, the control unit 43 controls the supply device 10, the printing device 20, the recovery device 30, the image processing unit 41, the memory unit 42, etc. based on various information and various programs stored in the memory unit 42. The control unit 43 also receives detection signals transmitted from the position detector 21e of the conveying unit 21 and the detection unit 22. The control unit 43 is realized, for example, by one or both of hardware and software.

(Inkjet head movement for maintenance)
For example, when performing a maintenance operation, the control unit 43 controls the moving mechanism 26 to move the ejection surface of each inkjet head 24 from a normal position H1 to a maintenance position H2. After the ejection surface of each inkjet head 24 moves to the maintenance position H2, the control unit 43 then moves the maintenance unit 27 to the maintenance position in the Y direction to perform maintenance on the ejection surface of each inkjet head 24. If necessary, the control unit 43 also moves the maintenance unit 27 to a position where the tray 27b of the maintenance unit 27 faces the ejection surface of each inkjet head 24, causes each inkjet head 24 to eject ink continuously, and then returns the maintenance unit 27 to its original position.

Here, the normal position H1, the maintenance position H2, etc. are usually set in advance and stored, for example, in the memory unit 42. However, the normal position H1, the maintenance position H2, etc. may be changed according to a predetermined condition, or may be changed according to an input operation by the user to the input device 40a.

(Inkjet head movement due to abnormal tablet height)
In addition, the control unit 43 judges whether the height of the tablet T on the conveyor belt 21a is abnormal based on the height information regarding the height of the tablet T detected by the detection unit 22 during tablet printing. For example, when the height of the tablet T exceeds a predetermined threshold, the control unit 43 judges that the height of the tablet T on the conveyor belt 21a is abnormal. As shown in FIG. 9, a tablet T with an abnormal height (hereinafter also referred to as a "height abnormal tablet") is, for example, a tablet in an upright position. The upright tablet T is in a state where the tablet T is in a vertical or inclined position relative to the conveying surface of the conveyor belt 21a, and when the tablet T is conveyed by the conveyor belt 21a toward directly below the inkjet head 24 while maintaining that position, it collides with the inkjet head 24 whose ejection surface is located at a predetermined normal position H1. The tablet T may be held in an upright position on the conveyor belt 21a by the suction action of the suction hole 21g. In particular, when the held surface of the tablet T has an R-shape, a point other than the center part of the tablet T may become the area to be sucked, and the tablet T may be held in an upright position.

The control unit 43 also changes the conveying speed at which the conveyor belt 21a conveys the tablets T, and also changes the distance between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24, based on whether the height of the tablets T on the conveyor belt 21a is abnormal. For example, when the height of the tablets T on the conveyor belt 21a is abnormal, the control unit 43 controls the conveyor unit 21 to reduce the conveying speed of the conveyor belt 21a, and controls the moving mechanism 26 to increase the distance between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24. After that, when the tablet T with an abnormal height passes directly under the inkjet head 24, the control unit 43 controls the moving mechanism 26 to return the inkjet head 24 to the normal position H1, and controls the conveyor unit 21 to return the conveying speed of the conveyor belt 21a to the original.

More specifically, as shown in FIG. 9, the control unit 43 controls the moving mechanism 26 so that the inkjet head 24 rises and the ejection surface of the inkjet head 24 moves from the predetermined normal position H1 to the predetermined retreat position H3 for the tablet T with an abnormal height. This widens the gap between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24. Even if the tablet T with an abnormal height reaches directly below the inkjet head 24 whose ejection surface is located at the predetermined retreat position H3 by the conveyor belt 21a in this state, the tablet passes directly below the inkjet head 24 without colliding with the inkjet head 24. After that, at the timing when the tablet T with an abnormal height passes directly below the inkjet head 24, the inkjet head 24 descends and the ejection surface of the inkjet head 24 moves from the predetermined retreat position H3 to the predetermined normal position H1. This returns the gap between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24 to the original position.

Here, the predetermined threshold value, the predetermined normal position H1, the predetermined evacuation position H3, etc. are usually set in advance and stored in the memory unit 42, for example. The normal position H1 is the lower limit of the movement range Ha of the ejection surface of the inkjet head 24, and the predetermined evacuation position H3 is a position lower than the maintenance position H2, which is the upper limit of the movement range Ha. However, the predetermined threshold value, the predetermined normal position H1, the predetermined evacuation position H3, etc. may be changed according to predetermined conditions, or may be changed according to the user's input operation to the input device 40a. The predetermined threshold value is set to, for example, the thickness of the tablet T + 1 mm. The distance between the printed surface of the tablet T and the ejection surface of the inkjet head 24 is usually about 1 mm, and the thickness of the tablet T is about 2 to 8 mm. Considering that the tablet T is 3 mm, when the height of the detected tablet T exceeds 4 mm, it exceeds the threshold value and is determined to be an abnormal tablet T, and the tablet T can be prevented from colliding with the inkjet head 24. The predetermined normal position H1 is, for example, a position (e.g., a height position 1 mm away from the printing surface of the tablet T) at which the inkjet head 24 does not collide with the tablet T lying on the conveyor belt 21a (normal position) and can print normally on the tablet T on the conveyor belt 21a, which is experimentally or theoretically determined and set. The predetermined retreat position H3 is a position (e.g., a height position away from the conveyor belt 21a that is equal to or greater than the major axis of the tablet T) at which the inkjet head 24 does not come into contact with the tablet T that is at an abnormal height above the conveyor belt 21a. Note that an appropriate margin is provided for both positions.

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

In addition, the control unit 43 sets the printability information for the tablet T for which the presence/absence information has been obtained based on the information on the damage or foreign matter adhesion of the tablet T transmitted from the image processing unit 41 (this information is information based on the first image). Then, the control unit 43 sets the printing conditions as printing condition information for the tablet T for which the presence/absence information has been obtained. At this time, the control unit 43 sets the printing conditions for the tablet T for which the position information has been obtained based on the position information in the X direction, Y direction, and θ direction of the tablet T transmitted from the image processing unit 41. For example, the control unit 43 determines the range of the nozzle 24a used to print the target tablet T in the inkjet head 24, that is, the nozzle range to be used, based on the position information in the Y direction of the tablet T and the printing data, and sets the printing conditions including the nozzle range to be used and the printing start timing. In addition, when the tablet T has a directional shape, the control unit 43 sets the printing conditions corresponding to the position of the tablet T in the θ direction based on the position information in the θ direction of the tablet T. As an example, the control unit 43 registers 180 different print patterns in the memory unit 42, in which the orientation of the print pattern is rotated by 1 degree in a range from 0 degrees to 179 degrees, and selects from among these print patterns a print pattern with an angle that matches the position of the tablet T in the θ direction, and sets the printing conditions.

The control unit 43 also determines whether the printing pattern has been printed in a predetermined shape and size at a predetermined position on the tablet T, i.e., whether the printing pattern has been printed normally on the tablet T, based on the printing position information, shape information, and size information of the printing pattern printed on the tablet T transmitted from the image processing unit 41 (these information are based on the second image), and sets the printing quality information of the tablet T (printing status inspection). For example, when determining the shape and size of the printing pattern, the control unit 43 registers a printing pattern for inspection in the memory unit 42, and compares the printing pattern for inspection with the printing pattern on the tablet T after actual printing (the printing pattern printed on the tablet T).

The control unit 43 appropriately stores various information (e.g., information on the presence or absence of damage or foreign matter on the tablet T, position information, tablet T height information, timing information, printability information, printing condition information, print quality information, etc.) in the memory unit 42. When the target tablet T is collected by the collection device 30, for example, when a predetermined time (e.g., several seconds) has elapsed since it fell from the downstream end of the conveying unit 21 in the conveying direction A1, the various information is deleted from the memory unit 42. However, if such information is required in a later process, it is possible to leave the various information for each tablet T without erasing it, or to store it in a storage medium outside the device. When storing the various information for each tablet T, this information may be linked to the manufacturing date and time, lot number, etc., and stored so that, for example, when a defective product occurs after shipping of the printed tablet T, the cause can be traced back.

(Printing process)
Next, the printing process performed by the above-mentioned tablet printing device 1 will be described with reference to Fig. 10. This printing process also includes an inspection process. Various information such as data required for printing and data required for retracting the inkjet head 24 is stored in advance in the storage unit 42.

As shown in FIG. 10, in step S1, when a large number of tablets T to be printed are placed in the hopper 11 of the supply device 10, the tablets T begin to be sequentially supplied from the hopper 11 to the alignment feeder 12, which then moves them in a line. The tablets T moving in a line are sequentially supplied to the conveyor belt 21a of the printing device 20 by the transfer feeder 13. The conveyor belt 21a rotates 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 lined up in a line on the conveyor belt 21a and conveyed at a predetermined conveying speed.

In step S2, the tablet T on the conveyor belt 21a is detected by the detection unit 22. More specifically, the tablet T on the conveyor belt 21a is detected by the detection unit 22 at the timing when it reaches a detection position (e.g., the laser light irradiation position) directly below the detection unit 22, and the X-direction position of the tablet T on the conveyor belt 21a is recognized by the control unit 43 based on the timing when the tablet T is detected. Then, position information indicating the X-direction position of the tablet T is generated by the control unit 43 and stored in the memory unit 42. In addition, the height of the tablet T on the conveyor belt 21a is detected by the detection unit 22, height information regarding the height of the tablet T is recognized by the control unit 43, and the height information of the tablet T is stored in the memory unit 42.

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

In step S4, the tablet T on the conveyor belt 21a is imaged by the first imaging unit 23. More specifically, the tablet T on the conveyor belt 21a is imaged by the first imaging unit 23 at the first imaging timing when the tablet T on the conveyor belt 21a reaches the imaging position directly below the first imaging unit 23, and the first image obtained by imaging by the first imaging unit 23 is transmitted to the control device 40. Based on this first image, information on the presence or absence of damage or foreign matter on the tablet T, as well as position information of the tablet T in the X direction, Y direction, and θ direction are generated by the image processing unit 41 and stored in the memory unit 42.

In step S5, the control unit 43 judges whether printing on the target tablet T is possible based on the information on the presence or absence of damage or foreign matter on the tablet T. If it is judged that printing on the target tablet T is possible (Yes in step S5), the process proceeds to step S6. In addition, based on the position information of the tablet T in the X direction, Y direction, and θ direction, and the printing pattern, the printing conditions including the nozzle range to be used and the printing start timing for the tablet T set as printable (printable tablet T) are set in the memory unit 42. Based on the above-mentioned printing start timing (timing to start printing on the tablet T), the ejection timing for the tablet T (timing to eject ink onto the tablet T) is determined. On the other hand, if it is judged that printing on the target tablet T is not possible (No in step S5), the process proceeds to step S9, and operations related to printing and inspection on the target tablet T are restricted. In addition, the printing possible/not possible information on the tablet T is appropriately stored in the memory unit 42. In addition, the "restriction" of the operations related to printing and inspection means that at least the processing related to printing and inspection on the target tablet T is not performed.

In step S6, printing is performed by the inkjet head 24 based on the above printing conditions. That is, the control unit 43 controls the inkjet head 24 to print a predetermined printing pattern on the printable tablets T on the conveyor belt 21a. In detail, the printable tablets T on the conveyor belt 21a that have passed under the first imaging unit 23 are printed by the inkjet head 24 based on the above printing conditions at the printing start timing when the tablets T reach the printing position directly below the inkjet head 24. In the inkjet head 24, ink is appropriately ejected from each nozzle 24a, and a printing pattern (e.g., numbers, alphabets, katakana, symbols, figures) is printed on the printing surface, which is the upper surface of the tablets T.

In step S7, the printed tablet T on the conveyor belt 21a is imaged by the second imaging unit 25. More specifically, the printed tablet T on the conveyor belt 21a is imaged by the second imaging unit 25 at the second imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 25, and the second image obtained by the imaging by the second imaging unit 25 is transmitted to the control device 40. This second image is processed by the image processing unit 41 of the control device 40. More specifically, information about the printed pattern printed on the tablet T, i.e., the printing position, shape, and size of the printed pattern, is acquired by the image processing unit 41. The second image transmitted from the second imaging unit 25 is processed by the image processing unit 41, and inspection information indicating the printing position, shape, and size of the printed pattern on the tablet T is generated and stored in the memory unit 42.

In step S8, the control unit 43 performs a print status inspection based on the above inspection information. In detail, the control unit 43 judges whether the print pattern has been printed normally on the tablet T based on the inspection information related to the print position, shape, and size stored in the memory unit 42, and print quality information indicating whether the tablet T is printed properly is generated and stored in the memory unit 42. For example, in the print status inspection, the print pattern used for printing is stored in the memory unit 42 as a print pattern for inspection, and quality information related to the specified print position, shape, and size of the print pattern for inspection is compared with inspection information related to the print position, shape, and size of the actually printed print pattern stored in the memory unit 42, and it is judged whether the print pattern has been printed normally on the tablet T (pass or fail).

In step S9, the tablets T on the conveyor belt 21a are collected by the collection device 30. The ink applied to the tablets T dries naturally during transport and is dried by the drying section 28. In detail, when the recycled tablets T reach the recycled product collection section 31 as the conveyor belt 21a moves, gas is sprayed onto the tablets T from above by the injection nozzle 31a, and the tablets T fall from the conveyor belt 21a and are collected in the collection box 31b. Similarly, when the defective tablets T reach the defective product collection section 32 as the conveyor belt 21a moves, gas is sprayed onto the tablets T from above by the injection nozzle 32a, and the tablets T fall from the conveyor belt 21a and are collected in the collection box 32b. In addition, when a good tablet T reaches a position near the end of the conveyor belt 21a on the side of each driven pulley 21c, the suction action on the tablet T ceases, and gas is blown onto the tablet T from above by the injection nozzle 33a, causing the tablet T to fall from the conveyor belt 21a and be collected in the collection box 32b. Such control of the blowing of gas is performed by the control unit 43 based on various information, such as position information of the tablet T, height information of the tablet T, printability information, and printability information.

In step S10, the control unit 43 determines whether printing has finished. For example, the number of printed tablets T is counted, and when that number reaches a predetermined production number, it is determined that printing has finished. If it is determined that printing has finished (Yes in step S10), the process ends. On the other hand, if it is determined that printing has not finished (No in step S10), the process returns to step S1. Note that, regarding the determination of printing finishing, printing may be determined to have finished in response to a user's input operation on the input device 40a, for example, in response to the user pressing a print finish button.

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

For example, the predetermined speed is determined based on the distance between the position directly below the detection unit 22 on the conveyor belt 21a and the position directly below the inkjet head 24, and the time required for the ejection surface of the inkjet head 24 to move from a predetermined normal position H1 to a predetermined retreat position H3. Note that the distance between the position directly below the detection unit 22 on the conveyor belt 21a and the position directly below the inkjet head 24 is, for example, the distance between the detection position where the detection unit 22 detects the tablet T on the conveyor belt 21a and the position directly below the upstream end of the inkjet head 24 in the conveying direction A1.

In step S12, the inkjet head 24 is raised by the movement mechanism 26. For example, the inkjet head 24 is raised until its ejection surface moves from a predetermined normal position H1 to a predetermined retreat position H3 (see FIG. 9). This causes the gap between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24 to expand to a predetermined retreat gap. This predetermined retreat gap is a gap that allows a tablet T with an abnormal height to pass directly below the inkjet head 24 without colliding with the inkjet head 24, even if the tablet T reaches directly below the inkjet head 24 by the conveyor belt 21a in that state.

In step S13, the control unit 43 restricts printing on the tablet T with an abnormal height, i.e., the abnormal height tablet T, and on multiple tablets T located before and after it. For example, the inkjet head 24 is raised by the moving mechanism 26 and ejection is suspended. This prevents the inkjet head 24 from printing on the abnormal height tablet T and tablets T transported before and after it (i.e., tablets T passing directly below the inkjet head 24 when the inkjet head 24 is located at a position higher than the normal position H1). As a result, it is possible to suppress the occurrence of tablets T with poor printing (printing failure). In other words, the control unit 43 stops printing on the tablets T by the inkjet head 24 at the same time as raising the inkjet head 24 by the moving mechanism 26.

In step S14, the control unit 43 judges whether or not the height-abnormal tablet T has passed directly below the inkjet head 24. If it is judged that the height-abnormal tablet T has passed directly below the inkjet head 24 (Yes in step S14), the process proceeds to step S15. For example, when a predetermined time has elapsed since the detection unit 22 detected the tablet T on the conveyor belt 21a, the control unit 43 judges that the height-abnormal tablet T has passed directly below the inkjet head 24. Note that whether or not the height-abnormal tablet T has passed directly below the inkjet head 24 may be determined by detection by the position detector 21e .

For example, the predetermined time is determined based on the conveying speed of the tablet T (changing conveying speed), the distance between the position directly below the detection unit 22 on the conveying belt 21a and the position directly below the inkjet head 24, and the amount of movement (amount of rotation) of the conveying belt 21a. Note that the distance between the position directly below the detection unit 22 on the conveying belt 21a and the position directly below the inkjet head 24 here is, for example, the distance between the detection position where the detection unit 22 detects the tablet T on the conveying belt 21a and the position directly below the downstream end of the inkjet head 24 in the conveying direction A1.

In step S15, the inkjet head 24 is lowered by the movement mechanism 26. For example, the inkjet head 24 is lowered until its ejection surface moves from a predetermined retracted position H3 to a predetermined normal position H1 (see FIG. 9). As a result, the distance between the conveying surface of the conveyor belt 21a and the ejection surface of the inkjet head 24 returns to the predetermined normal distance (the distance when the inkjet head 24 is located at the normal position H1).

In step S16, the conveying speed of the conveyor belt 21a is returned to the original speed by the control unit 43, and the process proceeds to step S9. For example, the conveying speed may be increased gradually or stepwise at a constant rate to a predetermined normal speed, or may be increased gradually or stepwise at a random rate. The predetermined normal speed is set in advance and is stored, for example, in the memory unit 42. However, the predetermined normal speed may be changed according to predetermined conditions, or may be changed according to a user's input operation on the input device 40a.

Even during such printing process, the cooling unit 61 (see FIG. 3) continues to take in outside air and supply it to the first region R1. The temperature of the air supplied to the first region R1 is at least lower than the temperature in the second region R2. This air with a lower temperature than the temperature in the second region R2 becomes cooling air. By supplying cooling air to the first region R1, the cooling air comes into contact with each inkjet head 24, cooling each inkjet head 24, and the cooling air flows toward the suction hole 21g for holding the tablet T after passing through each inkjet head 24, making it difficult for the airflow from the heat source 62 side to be sucked into the suction hole 21g. Alternatively, the air from the heat source 62 side is cooled by the cooling air and sucked into the suction hole 21g. This lowers the temperature of the air flowing near the suction hole 21g, and thus the temperature near the inkjet head 24.

Here, the target temperature in the vicinity of the inkjet head 24 is preferably, for example, 20 to 25 degrees. If cooling by the cooling unit 61 is not performed, the temperature in the vicinity of the inkjet head 24 will exceed 25 degrees. If the temperature in the vicinity of the inkjet head 24 exceeds 25 degrees, the possibility of a malfunction in the inkjet head 24 (such as a decrease in ink viscosity causing ejection defects) increases. Therefore, by lowering the temperature in the vicinity of the inkjet head 24 by supplying cooling air by the cooling unit 61, it is possible to suppress the decrease in the viscosity of the ink in the inkjet head 24 and the drying of the ink in the vicinity of the nozzle 24a, making it possible to suppress the occurrence of ejection defects and the occurrence of printing defects. In addition, it is possible to suppress the rise in the temperature of the ink in the inkjet head 24, making it possible to maintain the ink in an appropriate state, and suppressing the deterioration of the ink. Note that, according to an experiment, it was confirmed that the temperature in the vicinity of the inkjet head 24 can be lowered from 28 to 31 degrees to about 23 degrees by executing the supply of cooling air by the cooling unit 61.

Furthermore, a measuring device (not shown) may be provided to measure the temperature near the inkjet head 24, and when the measurement result of this measuring device exceeds a predetermined temperature (e.g., 24 degrees), the amount of cooling air supplied from the cooling unit 61 may be increased. Alternatively, when the measurement result of the measuring device exceeds the predetermined temperature, printing by the inkjet head 24 may be stopped. In this way, the occurrence of printing defects can be prevented. The measuring device for measuring the temperature near the inkjet head 24 may be provided near the inkjet head 24, or may be provided on the inkjet head 24 itself to measure the surface temperature of the inkjet head 24 itself. In other words, the temperature near the inkjet head 24 includes the temperature of the inkjet head 24 itself.

The cooling unit 61 is also configured to blow out cooling air avoiding the ejection surface of each inkjet head 24 that is moved by the moving mechanism 26. As a result, even if each inkjet head 24 is moved by the moving mechanism 26 to retreat from the tablet T or during maintenance, the cooling air blown out from the cooling unit 61 does not directly hit the ejection surface of each inkjet head 24, so that the ink near the nozzle 24a can be prevented from drying out and solidifying. This makes it possible to prevent ejection defects and printing defects.

In addition, the air in the second region R2 is exhausted to the outside of the device by the cooling unit 161, creating a negative pressure in the second region R2. The negative pressure in the second region R2 prevents heat generated in the second region R2 from flowing into the first region R1. The negative pressure in the second region R2 also makes it easier for the cooling gas from the cooling unit 61 to flow into the second region R2.

The length of the partition member 54 in the X direction is the same as the length of the conveying section 21 in the X direction. This prevents air from the second region R2 from flowing into the suction holes 21g in the conveying belt 21a that are not sucking up the tablets T. The upper end of the partition member 54 is connected to the ceiling of the housing 51. Warm air tends to move toward the top of the space. Therefore, by connecting the upper end of the partition member 54 to the ceiling of the housing 51, it is possible to prevent air heated in the second region R2 from flowing into the first region R1.

In addition, in response to the detection of the height abnormality by the detection unit 22, the control unit 43 reduces the conveying speed of the conveyor belt 21a and further increases the gap between the surface of the inkjet head 24 facing the conveyor belt 21a and the surface of the conveyor belt 21a facing the inkjet head 24. This allows tablets T with an abnormal height on the conveyor belt 21a to pass without colliding with the inkjet head 24. This makes it possible to suppress damage to the inkjet head 24 and breakage of the tablets T, thereby suppressing the adverse effects of increased maintenance frequency, extended maintenance time, breakage of the tablets T, etc., and allowing efficient printing on the tablets T.

The control unit 43 raises the inkjet head 24, and as soon as the tablet T with an abnormal height passes directly below the inkjet head 24, the inkjet head 24 returns to its original height position (normal position H1), the conveying speed of the conveyor belt 21a returns to the normal speed, and printing at the normal conveying speed is resumed. Printing by the inkjet head 24 is interrupted only during the raising of the inkjet head 24, the passing of the height-abnormal tablet T below the inkjet head 24, and the lowering of the inkjet head 24, and printing is performed when the inkjet head 24 is in the normal position H1, so that printing can be performed efficiently on the tablet T. In other words, printing cannot be performed on the tablet following the height-abnormal tablet T that is present at a distance corresponding to the length of the inkjet head 24 in the conveying direction A1, but printing can be resumed after the height-abnormal tablet T has passed the downstream end of the inkjet head 24 in the conveying direction A1, and the number of tablets T that become non-printed tablets due to the conveyance of the height-abnormal tablet T can be minimized. In addition, printing and inspection processes will be restricted for tablets T following the height abnormal tablet T, and these tablets T will also become non-printed tablets.

As long as the height-abnormal tablet T and the subsequent tablets (tablets present at a distance equal to the length of the inkjet head 24 in the conveying direction A1) pass the inkjet head 24 and the inkjet head 24 returns to its normal position H1, the control unit 43 can resume printing on the tablets T using the inkjet head 24. If the conveying speed of the conveyor belt 21a has been reduced, printing may be resumed after the conveying speed is returned to the normal speed as described above, but printing may also be resumed with the conveying speed reduced and the conveying speed returned to the original speed while printing continues.

Here, the supply speed at which tablets T are supplied from the supply device 10 to the conveying unit 21 (the conveying speed at which feeders such as the alignment feeder 12 and the delivery feeder 13 convey tablets T) is usually set to be slower than the conveying speed at which the conveying belt 21a conveys tablets T. For this reason, when the control unit 43 reduces the conveying speed of the conveying belt 21a so as to maintain a predetermined speed difference between the supply speed of the supply device 10 and the conveying speed of the conveying belt 21a, it may also reduce the supply speed of the supply device 10. This makes it possible to prevent tablets T from clogging feeders such as the alignment feeder 12 and the delivery feeder 13.

The control unit 43 may also control the supply device 10 to stop supplying new tablets T as soon as it detects a tablet T with an abnormal height. As a result, new tablets T are not supplied onto the conveyor belt 21a in response to the occurrence of a tablet T with an abnormal height. The maintenance unit 27 of the inkjet head 24 enters between the inkjet head 24 and the conveyor belt 21a to perform maintenance. At this time, the inkjet head 24 retreats to a position higher than the normal position H1 to create a space for the maintenance unit 27 to enter. Therefore, as soon as the tablets T on the conveyor belt 21a are collected, if new tablets T are not supplied to the conveyor belt 21a, maintenance work for the inkjet head 24 can be performed. Furthermore, maintenance of the conveyor belt 21a (and the suction holes 21g) may be performed at the same time as maintenance of the inkjet head 24 is performed.

The control unit 43 may also control the recovery device 30 to limit the ink ejection from the inkjet head 24 to tablets T that have passed directly below the detection unit 22 during the period when the conveying speed of the conveyor belt 21a has been reduced, and to recover tablets T that have passed directly below the detection unit 22 during the period when the conveying speed of the conveyor belt 21a has been reduced as reusable non-printed tablets, i.e., reusable products. This allows tablets T that have passed directly below the detection unit 22 during the period when the conveying speed of the conveyor belt 21a has been reduced to be recovered as reusable products.

In addition, in order to change the distance between the placement surface of the conveyor belt 21a and the ejection surface of the inkjet head 24, the inkjet head 24 is moved by the moving mechanism 26, but this is not limited to the above, and for example, the conveyor belt 21a may be moved by the moving mechanism 26. This movement of the conveyor belt 21a may be achieved by moving the entire conveyor unit 21 by the moving mechanism 26, or may be achieved by moving a part of the conveyor belt 21a facing the inkjet head 24 by the moving mechanism 26.

Here, when the transport object is a tablet T, the speed at which it passes under the inkjet head 24 is orders of magnitude faster than when the transport object is paper, for example, and the relative size difference between the transport object and the inkjet head 24 is large, and the transport interval between each transport object is also narrow. Therefore, it is not enough to simply prevent the transport object from colliding with the inkjet head 24, but it is important to devise a way to prevent the collision while reducing as much as possible the number of tablets T that are affected, such as being unable to print, by retracting the inkjet head 24 to prevent the collision. In addition, if the operation of the entire device is stopped upon detection of a tablet T with an abnormal height and the tablets T on the transport belt 21a are collected as unprinted (unprinted tablets), productivity will decrease significantly. Therefore, according to the present embodiment as described above, it is possible to solve problems specific to tablets that are not present in printing on paper. Note that, unlike printing on paper, when printing on tablets T, printing may be performed using one inkjet head 24 on multiple tablets T arranged in a direction perpendicular to the transport direction A1 in a horizontal plane.

As described above, according to the embodiment, the tablet printing device 1 includes a conveying unit 21 provided in the first region R1, which conveys the tablet T by suction and holding it in the suction hole 21g, an inkjet head 24 provided in the first region R1, which prints on the tablet T conveyed by the conveying unit 21, a heat source 62 provided in the second region R2 connected to the first region R1, and a cooling unit 61 that supplies gas at a temperature lower than that of the second region R2 to the first region R1. This makes it possible to supply gas at a temperature lower than that of the second region R2 to the first region R1, thereby lowering the temperature near the inkjet head 24 in the first region R1. Therefore, it is possible to suppress the decrease in viscosity of the ink in the inkjet head 24 and the drying of the ink near the nozzle 24a, and to suppress the occurrence of ejection defects, thereby suppressing the occurrence of printing defects. In addition, it is possible to suppress the rise in temperature of the ink in the inkjet head 24 and to properly maintain the ink, thereby suppressing the deterioration of the ink.

<Other embodiments>
In the above description, printing is performed on the tablets T using the tablet printing device 1 (tablet printing method) according to one embodiment, but this can also be rephrased as printing on the tablets T using the tablet printing device 1 (tablet printing method) according to one embodiment and manufacturing the printed tablets T. In other words, the tablet printing device 1 can be rephrased as a tablet manufacturing device, and the tablet printing method can be rephrased as a tablet manufacturing method.

In addition, in the above explanation, printing on one side of the tablet T was exemplified, but this is not limited to this. For example, the printing device 20 may be a single unit, and the units may be stacked vertically, and the tablet T printed by the upper printing device (first printing device) 20 may be inverted and handed over to the lower printing device (second printing device) 20, and the lower printing device 20 may print on the tablet T, thereby printing on both sides of the tablet T.

In addition, in the above description, the tablets T are conveyed in two rows, but this is not limited thereto, and the number of rows may be one row or multiple rows, such as three or more rows, and is not particularly limited. The number of conveyor belts 21a may be two or more, and is not particularly limited. The number of inkjet heads 24 may be one, three or more, and is not particularly limited.

In the above description, the cover 53 is formed from the main body 53b and the door portion 53c, but this is not limited to the above. For example, the side of the cover 23a facing the inkjet head 24 and the side of the cover 25a facing the inkjet head 24 may function as the side of the main body 53b. The holding portion 51a of the housing 51 may function as the ceiling of the main body 53b. The cover 23a, the cover 25a, and the ceiling of the cover 53 may be integrated. The cover 53 may be integrated without distinction between the main body 53b and the door portion 53c.

In addition, in the above description, the cover 23a covering the first imaging unit 23 and the cover 25a covering the second imaging unit 25 are exemplified, but this is not limiting. For example, the covers 23a and 25a are not essential, and the cover 53 may be configured to at least surround the periphery and upper side of the inkjet head 24 above the transport unit 21.

In the above description, the opening 54a of the partition member 54 is exemplified as a notch, but the shape of the opening 54a is not limited thereto. For example, when the holding portion 51a is not provided, the opening 54a may be a hole having a width that allows the maintenance portion 27 to move between the first region R1 and the second region R2. In this case, the lower end of the opening 54a is provided at a height that allows the maintenance portion 27 to move between the first region R1 and the second region R2. When the partition member 54 is connected to the ceiling of the housing 51, the first region R1 and the second region R2 are almost separated by the partition member 54. In this case, most of the heat generated in the second region R2 tries to flow into the first region R1 through the opening 54a. However, since the cooling gas from the cooling portion 61 is supplied to the space blocked by the cover 53, the heat generated in the second region R2 can be further prevented from flowing into the first region R1.

In addition, in the above description, a print head in which the nozzles 24a are arranged in a single row is used as the inkjet head 24, but this is not limited thereto, and for example, a print head in which the nozzles 24a are arranged in multiple rows may be used.

In the above description, the inkjet head 24 is illustrated as being arranged so that the direction in which the nozzles 24a are arranged is perpendicular to the transport direction A1 in a horizontal plane, but this is not limited thereto. For example, the nozzles 24a may be arranged so that the direction in which the nozzles 24a are arranged is perpendicular to the transport direction A1 in a horizontal plane.

In the above description, the tablets T are supplied randomly, not at regular intervals, onto the conveyor belt 21a, but this is not limited to this and they may be supplied at regular intervals. In the above description, the tablets T are suction-held by the suction holes 21g formed on the conveyor belt 21a, but this is not limited to this and they may be stored and held in a pocket or the like and transported, or they may be held and transported by their own weight on the conveyor belt 21a.

In the above description, the control unit 43 has been exemplified as determining whether the height of the tablet T is abnormal based on the height information regarding the height of the tablet T detected by the detection unit 22, but this is not limited to the above. For example, height information may be obtained by detecting the area, length, and shape of the tablet T supplied to the conveyor belt 21a when viewed in a plane (indirectly detecting the height of the tablet T) based on the image of the tablet T obtained by the first imaging unit 23. That is, the height of the tablet T may be determined to be abnormal when the area or length of the tablet T when viewed in a plane falls below a threshold value. Alternatively, the normal position H1 of the inkjet head 24 may be used as a reference, and a position approximately 1 mm lower than the normal position H1 may be set as the threshold value.

In the above description, the control unit 43 has been exemplified as causing the inkjet head 24 to print until the inkjet head 24 moves to the retracted position H3, or until the tablet T located one tablet upstream of the height abnormal tablet T, when the detection unit 22 detects the height abnormal tablet T, but this is not limited to the above. For example, when the detection unit 22 detects the height abnormal tablet T, printing by the inkjet head 24 may be interrupted and the inkjet head 24 may be moved from the normal position H1 to the retracted position H3. In this case, it is sufficient to reduce the conveying speed of the conveyor belt 21a to a speed that allows the inkjet head 24 to move to the retracted position H3 between the detection of the height abnormal tablet T and the arrival of the height abnormal tablet T in the inkjet head 24. Alternatively, the inkjet head 24 may be controlled to move to the retracted position H3 so that the tablets T for which printing is restricted are several tablets before and after the height abnormal tablet T (for example, about 10 tablets. Or, the time when about 10 tablets are expected to be conveyed). In this case, the speed difference before and after the transport speed of the transport belt 21a is reduced is small, and the number of prints per unit time can be increased.

In addition, in the above description, the conveying speed of the conveyor belt 21a is gradually or stepwise reduced as an example, but this is not limited thereto, and the conveying speed may be rapidly reduced to the target conveying speed when the detection unit 22 detects that the height of the tablet T has exceeded a predetermined threshold value. When the conveying speed of the conveyor belt 21a is returned to the normal speed from the reduced speed, it may be gradually or stepwise returned, or it may be rapidly returned, as in the case of reduction. In either case, changing the conveying speed gradually or stepwise is more effective in preventing the tablet T from coming off the conveyor belt 21a.

Here, the aforementioned tablets T can include tablets used for medicine, food, cleaning, industrial or aromatic purposes. Tablets T can be plain tablets, sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multi-layer tablets, dry-coated tablets, and various capsule tablets such as hard capsules and soft capsules. Tablets T can have various shapes such as disks, lenses, triangles, and ellipses. When the tablet T to be printed is for medicine or food, edible ink is preferably used. As the edible ink, any of synthetic dye ink, natural dye ink, dye ink, and pigment ink can 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 implemented 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.

LIST OF SYMBOLS 1 Tablet printing device 10 Feeding device 11 Hopper 12 Alignment feeder 13 Delivery feeder 20 Printing device 21 Conveying section 21a Conveying belt 21b Driving pulley 21c Driven pulley 21d Motor 21e Position detector 21f Suction chamber 21g Suction hole 22 Detection section 23 First imaging section 23a Cover 24 Inkjet head 24a Nozzle 25 Second imaging section 25a Cover 26 Moving mechanism 26a Arm 26b Arm moving mechanism 27 Maintenance section 27a Wiping section 27b Receiver 28 Drying section 30 Recovery device 31 Reusable product recovery section 31a Spray nozzle 31b Recovery box 32 Defective product recovery section 32a Spray nozzle 32b Recovery box 33 Non-defective product recovery section 33b Recovery box 33a Spray nozzle 40 Control device 40a Input device 40b Output device 41 Image processing section 42 Memory section 43 Control section 51 Housing 51a Holding section 52 Door 52a Opening 53 Cover 53a Ventilation section 53b Main body 53c Door section 54 Partition member 54a Opening 54b Plate 54c Frame 55 Door 61 Cooling section 62 Heat source 161 Cooling section A1 Conveying direction A2 Conveying direction Ha Movement range H1 Normal position H2 Maintenance position H3 Evacuation position T Tablet

Claims (12)

a conveying section provided in the first region for suctioning and holding the tablet in the suction hole and conveying the tablet;
An inkjet head provided in the first area for printing on the tablets transported by the transport unit;
A heat source provided in a second region connected to the first region and arranged to be aligned with the first region in a direction perpendicular to the conveying direction of the tablet conveyed by the conveying unit;
a cooling unit that supplies a gas having a temperature lower than that of the second region to the first region;
a housing that encloses the first area and the second area;
Equipped with
The cooling unit is configured to blow the gas toward the inkjet head, avoiding the surface of the inkjet head facing the conveying unit. the heat source is a heat source related to one or both of a transport operation of the transport unit and a printing operation of the inkjet head;
The tablet printing apparatus according to claim 1. the cooling unit is provided to face the heat source with the inkjet head therebetween in a direction intersecting a conveying direction of the tablet.
The tablet printing apparatus according to claim 1. The cooling unit blows out the gas in a direction intersecting a conveying direction of the tablet within a horizontal plane.
The tablet printing apparatus according to claim 3. the inkjet head may further include a moving mechanism that moves the conveying unit or the inkjet head so as to change a distance between a surface of the inkjet head on the conveying unit side and a surface of the conveying unit on the inkjet head side,
the cooling unit is provided to blow out the gas while avoiding a surface of the inkjet head moved by the moving mechanism that faces the transport unit.
The tablet printing apparatus according to claim 1. The moving mechanism is provided in the second area,
a partition member which is a wall for separating the first area from the second area and has an opening for connecting the moving mechanism to the inkjet head;
The tablet printing apparatus according to claim 5. a cover provided on the partition member and partitioning the first area in the tablet conveying direction by two surfaces opposed to each other across the inkjet head;
the cooling unit is provided on one side of the space between the two surfaces of the cover in a direction perpendicular to the conveying direction, and the partition member has an opening on the other side.
7. The tablet printing apparatus according to claim 6. a first imaging unit that is located upstream of a position where the inkjet head is provided in a conveying direction of the tablet and is provided above the conveying unit;
a first cover that is not in contact with the transport unit and is provided to surround the first imaging unit;
a second imaging unit located downstream of the position where the inkjet head is provided in the tablet conveying direction and provided above the conveying unit;
a second cover that is not in contact with the transport unit and is provided to surround the second imaging unit;
Further equipped with
the cover that divides the first area in the tablet conveying direction by two surfaces that face each other across the inkjet head is a third cover provided between the first cover and the second cover;
The tablet printing apparatus according to claim 7. the cover, which divides the first area in the tablet conveying direction by two surfaces facing each other across the inkjet head, has a door portion capable of opening and closing one side of the space between the two surfaces;
The tablet printing apparatus according to claim 8. A detection unit that detects height information of the tablet on the conveying unit;
A control unit that controls the movement mechanism;
Further equipped with
The control unit controls the moving mechanism to widen the gap when the height of the tablet exceeds a predetermined threshold based on the height information detected by the detection unit.
The tablet printing apparatus according to claim 5. a maintenance unit that is provided in the second area and moves between the second area and the first area to perform maintenance work on the inkjet head,
The tablet printing apparatus according to any one of claims 1 to 10. a conveying unit provided in a first region in the housing sucks and holds the tablet in a suction hole and conveys the tablet;
an inkjet head provided in the first region prints on the tablets transported by the transport unit;
a cooling unit is provided in the housing so as to be aligned with the first region in a direction perpendicular to a conveying direction of the tablet conveyed by the conveying unit, and in a state in which a heat source is present in a second region connected to the first region, the cooling unit supplies gas having a temperature lower than that of the second region to the inkjet head, avoiding a surface of the inkjet head on the conveying unit side;
A tablet printing method comprising:

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