JP2017176763A - Tablet printing apparatus and tablet printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tablet printing apparatus and a tablet conveying method which can suppress the occurrence of printing failure of tablets.SOLUTION: A tablet printing apparatus 1 includes: a conveyor belt 21 which conveys a tablet T; an ink jet head 61 which discharges ink from a discharge port to the tablet T conveyed by the conveyor belt 21 and performs printing on the tablet T placed on a surface M1 of the conveyor belt 21; an image processing apparatus 110 which functions as a powder adhesion detection device for detecting the degree of powder adhesion of the tablet T with respect to the surface M1 of the conveyor belt 21 on the basis of the image of the surface M1 of the conveyor belt 21; and a control device 120 which varies the speed of conveying the tablet by the conveyor belt in accordance with the degree of powder adhesion detected by the image processing apparatus 110.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a tablet printing apparatus and a tablet printing method.

  2. Description of the Related Art Currently, tablet printing apparatuses that perform printing using an inkjet head in order to print identification information such as characters and symbols on tablets are known. The tablet printing apparatus transports tablets by a transport belt, and discharges ink from a discharge port (nozzle opening) of an ink jet head arranged above the transport belt toward a tablet passing under the ink jet head. The identification information is printed on the tablet.

  Normally, in a tablet printing apparatus, a large number of tablets (for example, tablets obtained by compression molding powder or granules) are sequentially conveyed by a conveyance belt, and thus the tablet powder accumulates on the conveyance belt. As the amount of accumulated powder increases, powder enters between the transport belt and the tablet, and the tablets on the transport belt are not sufficiently held, causing a transport failure such as dropping from the transport belt. Sometimes. For this reason, there exists the present condition that cleaning of a conveyance belt is performed before the accumulation amount of powder exceeds the quantity which causes a conveyance defect.

JP-A-7-081050

  The problem to be solved by the present invention is to provide a tablet printing apparatus and a tablet printing method capable of suppressing the occurrence of defective printing of tablets.

  A tablet printing apparatus according to an embodiment of the present invention includes a conveyance belt that conveys tablets, a printing apparatus that performs printing on tablets conveyed by the conveyance belt, and a powder adhesion that detects the degree of powder adhesion of tablets to the surface of the conveyance belt. A detection device and a control device that varies the speed at which the tablet is conveyed by the conveyance belt according to the degree of powder adhesion detected by the powder adhesion detection device.

  A tablet printing method according to an embodiment of the present invention is a tablet printing method in which tablets are transported by a transport belt and printing is performed on the tablets transported by the transport belt, and the tablet powder adhesion degree on the surface of the transport belt is determined. A step of detecting by the powder adhesion detection device, and a step of varying the speed at which the tablets are conveyed by the conveyance belt in accordance with the degree of powder adhesion detected by the powder adhesion detection device.

  According to the embodiment of the present invention, it is possible to suppress the occurrence of tablet printing defects.

It is a figure which shows schematic structure of the tablet printing apparatus which concerns on one Embodiment. It is a top view which shows a part of tablet printing apparatus which concerns on one Embodiment. It is a figure which shows schematic structure of the belt cleaning apparatus which concerns on one Embodiment. It is a flowchart which shows the flow of the printing process which the tablet printer which concerns on one Embodiment performs. It is a schematic diagram which shows the relationship between the powder adhesion degree ratio and conveyance speed of the tablet printer which concerns on one Embodiment. It is a figure which shows schematic structure of the belt cleaning apparatus which concerns on other embodiment.

  An embodiment will be described with reference to the drawings.

  Here, as described above, in the tablet printing apparatus, the powder of the tablets to be transported causes a defect in the transport of the tablets as described above, but earlier than the transport failure in which the tablets fall from the transport belt is caused. In some cases, the tablets being conveyed are displaced or rocked, resulting in printing failure. With respect to this phenomenon, the present inventors have found that there is a correlation between the degree of powder adhesion (powder adhesion degree) to a conveyance belt that conveys tablets, printing defects, and conveyance speed. This embodiment to be described below is based on this knowledge.

(Basic configuration)
As shown in FIG.1 and FIG.2, the tablet printing apparatus 1 which concerns on one Embodiment is the supply apparatus 10, the conveying apparatus 20, the detection apparatus 30, the 1st imaging device 40, and the 2nd imaging apparatus. 50, a printing device 60, a third imaging device 70, a collection device 80, a head cleaning device 90, a belt cleaning device 100, an image processing device 110, and a control device 120.

  The supply device 10 includes a hopper 11 and a shooter 12. The hopper 11 stores a large number of tablets T, and sequentially supplies the stored tablets T to the shooter 12. The shooter 12 aligns the supplied tablets T in a plurality of rows (two rows in the example of FIG. 2), and supplies them to the transport device 20. The supply device 10 is electrically connected to the control device 120, and its driving is controlled by the control device 120.

  The transport device 20 includes a transport belt 21, a drive pulley 22, a plurality of (three in the example of FIG. 1) driven pulleys 23, a drive unit 24, and a suction unit 25. The conveyor belt 21 is formed in an endless shape, and is stretched over the driving pulley 22 and each driven pulley 23. The drive pulley 22 and each driven pulley 23 are provided so as to be rotatable about an axis, and the drive pulley 22 is connected to a drive unit 24. The drive unit 24 is, for example, a motor, and is electrically connected to the control device 120, and the drive thereof is controlled by the control device 120. The drive unit 24 includes a position detector 24a such as a rotary encoder. The position detector 24 a transmits a detection signal to the control device 120. The control device 120 can obtain information such as the position, speed, and movement amount of the conveyor belt 21 based on the detection signal. The transport device 20 rotates the transport belt 21 together with each driven pulley 23 by the rotation of the drive pulley 22 by the drive unit 24, and the tablet T on the transport belt 21 is transported in the direction indicated by the arrow A1 in FIG. 1 and FIG. Transport in direction A1). Hereinafter, the speed at which the tablets T are transported by the transport belt 21 is referred to as the speed of the transport belt 21.

  Here, as shown in FIG. 2, a plurality of circular suction holes 21 a are formed on the surface M <b> 1 of the conveyor belt 21. Each of these suction holes 21a is a through hole that adsorbs the tablet T, and is arranged in two rows in parallel along the transport direction A1 so as to form two transport paths. Each suction hole 21 a is connected to the suction part 25, and a suction force can be obtained by the suction part 25. The suction unit 25 sucks and holds the tablets T on the surface M1 of the transport belt 21 through the suction holes 21a. The tablet T is placed on the surface M1 of the transport belt 21 by the supply device 10.

  The detection device 30 includes a plurality of detection units 31 (two in the example of FIG. 2). The detection units 31 are arranged downstream of the supply device 10 in the transport direction A1 and in a direction intersecting the transport direction A1 in the horizontal plane (for example, a direction orthogonal), and one transport belt for each transport path of the tablets T. 21 is provided above. These detection units 31 detect the tablets T on the conveyor belt 21 by projecting and receiving laser light. As the detection unit 31, for example, various laser sensors such as a reflective laser sensor can be used. Various shapes such as spots and lines can be used as the beam shape of the laser light. Each detection unit 31 is electrically connected to the control device 120 and transmits a detection signal to the control device 120.

  The first imaging device 40 includes a plurality of imaging units 41 (two in the example of FIG. 2), and functions as an imaging device that acquires an image for detecting the degree of powder adhesion on the conveyor belt 21. The imaging unit 41 is located at a position where the tablet T does not exist on the transport belt 21, for example, a direction upstream from the supply device A in the transport direction A1 and intersects the transport direction A1 in the horizontal plane (for example, a direction orthogonal). Are arranged above the conveyor belt 21. The imaging unit 41 always captures the image of the conveyor belt 21 at a position where the tablet T is not placed on the surface M1 of the conveyor belt 21, and acquires an image of the surface M1 of the conveyor belt 21 (an image for detecting the degree of adhesion of powder). The acquired image is transmitted to the image processing apparatus 110. As the imaging unit 41, for example, various cameras having an imaging element such as a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor) can be used. Each imaging unit 41 is electrically connected to the control device 120 via the image processing device 110, and their driving is controlled by the control device 120. Note that illumination for imaging is also provided as necessary.

  The second imaging device 50 includes a plurality of imaging units 51 (two in the example of FIG. 2), and includes defects such as breakage (for example, chipping) and contamination of the tablets T supplied on the conveyor belt 21. It functions as a detection device that detects the position. The imaging units 51 are arranged downstream of the detection device 30 in the transport direction A1 and in a direction intersecting the transport direction A1 in the horizontal plane (for example, a direction orthogonal), and one transport belt for each transport path of the tablets T. 21 is provided above. The imaging field of view of the imaging unit 51 is set to a size that allows at least one tablet T conveyed by the conveyor belt 21 to enter. For example, the imaging unit 51 performs imaging at the timing when the tablet T arrives directly below, acquires an image including the upper surface of the tablet T (image for detecting the tablet position), and transmits the acquired image to the image processing apparatus 110. . The timing at which the tablet T reaches immediately below the imaging unit 51 can be calculated by the position detector 24a described above, triggered by the detection of the tablet T by the detection device 30. As the imaging unit 51, for example, various cameras having an imaging element such as a CCD or a CMOS can be used. Each imaging unit 51 is electrically connected to the control device 120 via the image processing device 110, and their driving is controlled by the control device 120. Note that illumination for imaging is also provided as necessary.

  The printing apparatus 60 includes a plurality of inkjet heads 61 (two in the example of FIG. 2). The inkjet head 61 is arranged downstream of the second imaging device 50 in the transport direction A1 and in a direction intersecting the transport direction A1 in a horizontal plane (for example, a direction orthogonal), and one for each transport path of the tablet T. It is provided above the conveyor belt 21 one by one. The inkjet head 61 includes a plurality of ejection openings 61a (see FIG. 2), and individually ejects ink from these ejection openings (nozzle openings) 61a. The inkjet head 61 is provided so that the alignment direction in which the discharge ports 61a are arranged intersects the transport direction A1 in a horizontal plane (for example, to be orthogonal). As the ink jet head 61, for example, various ink jet heads having drive elements such as piezoelectric elements, heat generating elements, or magnetostrictive elements can be used. Each inkjet head 61 is electrically connected to the control device 120, and their driving is controlled by the control device 120.

  The third imaging device 70 includes a plurality of imaging units 71 (two in the example of FIG. 2), and functions as a print inspection device that detects the printing state of the tablets T printed on the transport belt 21. The imaging unit 71 is arranged downstream of the printing apparatus 60 in the transport direction A1 and in a direction intersecting the transport direction A1 in a horizontal plane (for example, a direction orthogonal), and one transport belt for each transport path of the tablets T. 21 is provided above. The imaging field of view of the imaging unit 71 is set to a size that allows at least one tablet T to be transported by the transport belt 21. The imaging unit 71 performs imaging at the timing when the tablet T arrives directly below, acquires an image including the upper surface of the tablet T (image for printing state inspection), and transmits the acquired image to the image processing apparatus 110. As the imaging unit 71, for example, various cameras having an imaging element such as a CCD or a CMOS can be used. Each imaging unit 71 is electrically connected to the control device 120 via the image processing device 110, and their driving is controlled by the control device 120. Note that illumination for imaging is also provided as necessary.

  The collection device 80 is positioned downstream of the third imaging device 70 in the transport direction A1, and is provided at the downstream end of the transport device 20 in the transport direction A1. The collection device 80 is configured to be able to sequentially receive and collect the tablets T that are dropped when the holding by the conveyance device 20 is released. In addition, the conveyance apparatus 20 cancels | releases holding | maintenance of the tablet T, when each tablet T on the conveyance belt 21 reaches | attains a desired position, for example, the downstream edge part of the conveyance direction A1 in the conveyance apparatus 20. FIG.

  As shown in FIG. 2, the head cleaning device 90 is provided at a standby position adjacent to the negative end (−end) side of the transport belt 21 in the Y direction. The head cleaning device 90 is configured to be movable by a moving mechanism (not shown) to a standby position and a cleaning position located between the upper surface of the transport belt 21 and the lower surface of each inkjet head 61. During cleaning, the head cleaning device 90 moves from the standby position to the cleaning position, cleans the lower surface (nozzle surface) of each inkjet head 61 positioned individually above the two rows of transport paths, and discharges the outlet 61a and its Powder is removed from around the discharge port 61a. As the head cleaning device 90, for example, a wipe mechanism such as a blade, cloth, or brush, or a vacuum wipe mechanism in which a suction mechanism for sucking air is combined with the wipe mechanism can be used. The head cleaning device 90 is electrically connected to the control device 120, and its driving is controlled by the control device 120.

  The belt cleaning device 100 is positioned below each driven pulley 23 side of the transport belt 21 and is provided at a position facing the surface M <b> 1 of the transport belt 21. The belt cleaning device 100 sequentially cleans the surface M <b> 1 of the conveyor belt 21 as the conveyor belt 21 moves. The belt cleaning device 100 is electrically connected to the control device 120, and its driving is controlled by the control device 120.

  As shown in FIG. 3, the above-described belt cleaning device 100 includes a cleaning brush 101, a gas blowing unit 102, and a gas suction unit 103.

  The cleaning device 100 is provided at a position facing the surface M1 of the transport belt 21, and can be moved toward the transport belt 21 by a moving mechanism (not shown). The cleaning brush 101 is, for example, a brush roller, contacts the surface M1 of the moving conveyor belt 21, and sweeps the surface M1 by rotating in the direction opposite to the rotation direction of the conveyor belt 21. The powder of the tablet T adhering to the surface M1 is removed. The cleaning brush 101 is pressed against the transport belt 21 by a pressing mechanism 101a. The pressing mechanism 101a is a member such as a spring, for example, and the cleaning brush 101 is provided in the gas spraying portion 102 via the pressing mechanism 101a. The pressing mechanism 101 a is formed so as to be able to vary the pressing force that presses the cleaning brush 101 against the transport belt 21. The cleaning device 100 is electrically connected to the control device 120, and the drive for moving in the direction toward the transport belt 21 is controlled by the control device 120. Under the control of the control device 120, the cleaning brush 101 is moved between a position where it does not contact the surface M1 of the conveyor belt 21 and a position where it contacts, or the pressing force by the pressing mechanism 101a is controlled.

  The gas spraying part 102 is formed in a shape that covers the cleaning brush 101, and is provided so as to spray gas toward the cleaning brush 101. A gas supply mechanism 102a is connected to the gas blowing unit 102, and gas (for example, air) is supplied from the gas supply mechanism 102a. The gas supply mechanism 102 a is electrically connected to the control device 120, and its driving is controlled by the control device 120. For example, the control device 120 controls a gas spray force and a spray amount by the gas spray unit 102.

  The gas suction part 103 is formed in a hollow shape and is provided around the gas blowing part 102. A gas suction mechanism 103a having a suction pump or the like is connected to the gas suction portion 103, and a suction force is applied around the gas blowing portion 102 by the gas suction mechanism 103a. The gas suction mechanism 103 a is electrically connected to the control device 120, and its driving is controlled by the control device 120. For example, the control device 120 controls the gas suction force and the suction amount by the gas suction unit 103.

  Such a belt cleaning apparatus 100 removes the powder adhering to the conveyance belt 21 by the sweeping operation of the cleaning brush 101 and the gas spraying operation by the gas spraying unit 102, and comes out from the gap between the gas spraying unit 102 and the transporting belt 21. Powder is sucked together with air by the gas suction unit 103. Thus, the powder adhering to the conveyance belt 21 can be reliably removed by the cleaning brush 101 and the gas blowing unit 102. Further, the gas suction unit 103 can prevent the powder once removed from adhering to the surrounding apparatus or reattaching to the transport belt 21.

  Returning to FIG. 1, the image processing apparatus 110 includes an image for powder state detection captured by the first imaging device 40, an image for tablet position detection captured by the second imaging device 50, and a third imaging device. The image for the printing state inspection imaged by 70 is captured, and the image is processed using a known image processing technique.

  For example, the image processing apparatus 110 processes an image for detecting the degree of powder adhesion obtained from the first imaging device 40 (binarization processing is performed as an example), and the powder of the tablet T is the surface M1 of the transport belt 21. Detects the degree of powder adhesion on the surface. This degree of powder adhesion can be based on, for example, the color density of the powder adhered to the conveyor belt 21. Specific detection of color density will be described later. Therefore, the image processing apparatus 110 functions as a powder adhesion detection apparatus that detects the degree of powder adhesion of the transport belt 21.

  Further, the image processing device 110 processes the image for detecting the tablet position obtained from the second imaging device 50, detects defects such as breakage and dirt of the tablet T, and the X direction (conveyance of the tablet T). The position in the direction A1), the Y direction and the θ direction is detected (see FIG. 2).

  The detection result of the defect of the tablet T, that is, the defect information of the tablet T is whether or not the tablet T has a defect such as breakage or contamination of the tablet T based on the result of the image processing. It is stored in the apparatus 110 and is obtained by comparing the correct tablet image with the actual tablet image.

  Further, the positions in the X direction and the Y direction are, for example, positions in the XY coordinate system with respect to the center of the imaging field of the imaging unit 51. Further, the position in the θ direction is a position indicating the degree of rotation of the tablet T with respect to the center line in the Y direction of the imaging field of the imaging unit 51, for example. This position in the θ direction is detected when the tablet T is in a directional form, such as when the tablet T is provided with a dividing line, or when the tablet T is molded into an ellipse, oval, square, or the like. Is done. Further, the image processing apparatus 110 processes the image for printing state inspection of the tablet T, which has been printed by the inkjet head 61, obtained from the third imaging apparatus 70, and the print pattern printed on the tablet T. A print position (for example, a character or a mark) is detected.

  The image processing apparatus 110 described above detects the powder adhesion degree information of the conveyor belt 21 detected as described above, defect information of each tablet T, position information of each tablet T in the X direction, Y direction, and θ direction, and each tablet. The print position information of the print pattern on T is transmitted to the control device 120. In addition, when the image processing apparatus 110 transmits each information, the identification information of each imaging part 41, 51, 71 is added and transmitted to those information. Thereby, the control apparatus 120 can grasp | ascertain the transmitted information is the positional information corresponding to which imaging part among each imaging part 41,51,71.

  The control device 120 includes a microcomputer that centrally controls each unit and a storage unit (none of which is shown) that stores processing information and various programs. The control device 120 includes a supply device 10, a transport device 20, a first imaging device 40, a second imaging device 50, a printing device 60, a third imaging device 70, and a head cleaning device based on various information and various programs. 90. The belt cleaning device 100 and the image processing device 110 are controlled. The control device 120 receives a detection signal transmitted from the detection device 30 or the position detector 24a.

  Based on the defect information of the tablet T transmitted from the image processing apparatus 110, the control device 120 prohibits printing on the tablet T when the tablet T has a defect such as breakage or smudge. T is recovered by a recovery container (not shown) other than the recovery device 80. On the other hand, if there is no defect in the tablet T, printing on the tablet T is permitted.

  Further, the control device 120 determines, based on the powder adhesion degree information of the conveyor belt 21 transmitted from the image processing device 110, the powder adhesion degree that the powder of the tablet T adheres to the surface M1 of the conveyor belt 21 from a predetermined value. Determine if it is high. For example, when the control device 120 determines that the above-described degree of powder adhesion is higher than a predetermined value, the control device 120 performs cleaning of the inkjet head 61 or the transport belt 21, while determining that the powder adhesion degree is equal to or less than a predetermined value. In such a case, the printing operation is permitted (details will be described later).

  Moreover, the control apparatus 120 drives the conveyance belt 21 at the speed of the conveyance belt 21 corresponding to the powder adhesion degree according to the above-mentioned powder adhesion degree. For example, as shown in FIG. 5, the relationship between the degree of powder adhesion and the speed of the conveyor belt 21 is obtained in advance by experiments or the like and stored in the control device 120 as a relational expression or a relation table. Then, the control device 120 adjusts the speed of the conveyor belt 21 based on the degree of powder adhesion at a predetermined timing based on the stored relational expressions and relation tables.

  Further, the control device 120 performs the control on the tablet T in which the positions in the X direction, the Y direction, and the θ direction are detected based on the position information of the tablet T in the X direction, the Y direction, and the θ direction transmitted from the image processing apparatus 110. Set the printing conditions. The storage unit stores print data including a print pattern such as characters and symbols, a print position of the print pattern on the tablet T, and moving speed data of the transport belt 21. For example, the control device 120 determines the use range of the nozzle (discharge port 61a) used for the current printing in the inkjet head 61 based on the position information of the tablet T in the Y direction, and uses the position information of the tablet T in the X direction. Based on this, the timing for starting printing on the tablet T is determined. Further, the control device 120 sets the printing conditions in correspondence with the position of the tablet T in the θ direction based on the position information of the tablet T in the θ direction. As an example, 180 types of print data obtained by rotating the print pattern orientation by 1 degree each in the range of 0 to 179 degrees are registered in the storage unit of the control device 120 and detected from the print data. The print condition is set by selecting print data having an angle suitable for the position in the θ direction.

  Further, the control device 120 determines whether or not a print pattern (for example, a character or a mark) has been normally printed on the tablet T based on the print position information of the print pattern of the tablet T transmitted from the image processing device 110. to decide. This is performed by storing the correct print pattern in the control device 120 in advance and comparing the correct print pattern with the print pattern on the tablet T after actual printing. When the control device 120 determines that the print pattern is normally printed on the tablet T, the control device 120 collects the tablet T that has passed the inspection by the collection device 80. On the other hand, if it is determined that the print pattern has not been printed normally on the tablet T, the tablet T that fails the inspection is collected by a collection container other than the collection device 80.

(Printing process)
Next, a printing process (printing process) performed by the tablet printing apparatus 1 described above will be described with reference to FIG. 4 (see also FIG. 1 as appropriate). Various information such as print data required for printing is stored in the storage unit of the control device 120 until printing is performed, and the tablet T to be printed is stored in the hopper 11 of the supply device 10. Many have been introduced.

  As shown in FIG. 4, in step S <b> 1, the conveyance belt 21 of the conveyance device 20 is driven in a state where the supply of the tablet T from the supply device 10 to the conveyance device 20 is stopped. The transport belt 21 rotates in the transport direction A <b> 1 as the driving pulley 22 and the driven pulleys 23 are rotated by the driving unit 24. The conveyor belt 21 is driven at a preset speed with respect to the inkjet head 61. The speed of the transport belt 21 is obtained by multiplying the rated speed V of the transport apparatus 20 by the speed coefficient k. The speed coefficient k is determined by experiments or the like corresponding to the degree of powder adhesion of the conveyor belt 21 as will be described later. In step S1 where the driving of the conveyor belt 21 is first started, the above-described speed coefficient k is set to 1.0 as an initial value. As a result, the speed of the conveyor belt 21 becomes the rated speed V.

  In step S <b> 2, imaging of the surface M <b> 1 (the placement surface of the tablet T) of the transport belt 21 is started by the first imaging device 40. In step S3, the tablets T are sequentially supplied from the supply device 10 onto the conveyor belt 21 while the conveyor belt 21 is rotating. In step S4, the degree of powder adhesion of the conveyor belt 21 is measured. That is, in a state where the conveyor belt 21 is moving, images are continuously captured by the imaging units 41 of the imaging device 40, and images of the conveyor belt 21 are sequentially acquired. The image for detecting the degree of powder adhesion on the conveyor belt 21 is processed by the image processing apparatus 110, and the information on the degree of powder adhesion on the conveyor belt 21 is sequentially generated.

  In step S5, it is determined whether or not the powder adhesion degree of the conveyor belt 21 is higher than a predetermined value based on the above-described powder adhesion degree information of the conveyor belt 21. This step S5 determines whether or not the conveyor belt 21 needs to be cleaned. In the determination of the degree of powder adhesion, for example, it is determined whether or not the color density of the powder adhered to the conveyance belt 21 is higher than a predetermined value, and the degree of powder adhesion of the powder adhered to the conveyance belt 21 is determined. In addition, since the supply of the tablet T is in a stopped state in the first determination stage, it is determined that no powder adheres to the conveyor belt 21 and the degree of powder adhesion is not higher than a predetermined value (NO). Become.

  Here, as a method of detecting the above-described color density, the gradation of the conveyor belt 21 used in advance is measured, and this is set as zero. For example, when the conveyor belt 21 is black, the black of the conveyor belt 21 in a state where no powder is attached is set as zero. For example, when white tablet powder adheres to the conveyor belt 21, the output value shifts to a value higher than zero as the gradation changes. A predetermined value is set in this output value, and when the output value is higher than the predetermined value, it is determined that the degree of powder adhesion is high. Note that the degree of powder adhesion is determined on the condition that the output value continues to be higher than the predetermined value for a predetermined time or more in order to distinguish from the fact that dust other than powder adheres to the conveyor belt 21 and the output value increases. It is desirable to do so.

  If it is determined in step S5 that the powder adhesion degree of the conveyor belt 21 is not higher than a predetermined value (NO), whether or not the speed coefficient k related to the speed of the conveyor belt 21 needs to be updated in step S6. to decide. This determines whether or not the current speed coefficient k is the speed coefficient k corresponding to the degree of powder adhesion measured in step S4. If the current speed coefficient k is different from the current speed coefficient k, the speed coefficient k is updated. . That is, as the printing process on the tablet T progresses and powder accumulates on the transport belt 21, the degree of powder adhesion changes greatly. As shown in FIG. 5, the speed coefficient k also changes corresponding to the changed degree of powder adhesion. Therefore, if the speed coefficient k corresponding to the degree of powder adhesion measured in step S4 is the same as the currently set speed coefficient k, if it is different, it is determined that updating is necessary and the speed coefficient k Is updated to a new coefficient (step S7), and if not different, the process proceeds to the next step S8 without updating.

  By the way, as described above, the speed coefficient k is obtained by experiments or the like. This is to obtain in advance an experiment or the like the relationship between the degree of powder adhesion, the state of printing on the tablet T, and the speed of the conveyor belt 21. Furthermore, since these relationships vary depending on the type of tablet T, it is determined for each type of tablet T.

  Specifically, the quality of printing is checked on the conveyor belt 21 having various degrees of powder adhesion. The quality criterion for printing at this time is, for example, the visibility of the printed identification information or the displacement of the position. And in the conveyance belt 21 of various powder adhesion degrees, the speed of a conveyance belt is changed and the quality of printing is investigated similarly. From the results of these investigations, the relationship between the degree of powder adhesion at which the printing state is good and the speed of the conveyor belt 21 is obtained. As a result, the speed coefficient k, which is the ratio of the speed of the conveyor belt 21 that is good for printing, corresponding to the degree of powder adhesion, to the rated speed V is obtained and stored in the control device 120.

  FIG. 5 is a schematic diagram showing the relationship between the degree of powder adhesion and the speed coefficient k at which printing is good. The vertical axis represents the speed coefficient k, and the upper limit is 1.0. The horizontal axis represents the powder adhesion ratio, and is represented by a ratio (%) where a predetermined value serving as a reference for determining whether or not to clean the transport belt 21 is 100.

  As shown in FIG. 5, when the degree of powder adhesion increases, the speed coefficient of the conveyor belt 21 that improves printing becomes smaller. Further, the rate coefficient does not decrease so much until the degree of powder adhesion is around 30%, but the rate coefficient decreases from about 50%. That is, when the degree of powder adhesion increases, printing on the tablet T becomes defective, but by decreasing the speed of conveyance of the tablet T, printing does not become defective. And it has shown that the conveyance speed of the tablet T which does not make printing defective, ie, the speed of the conveyance belt 21, decreases rapidly as the powder adhesion degree increases. This is due to the influence of the powder existing between the tablet T and the conveyor belt 21, and the holding force of the tablet T is weakened. Therefore, the influence of the airflow caused by the movement of the tablet T is relatively increased, and the tablet T is displaced. This is thought to be because of or shaking. Depending on the shape of the tablet, the influence of this air flow may be particularly large.

  As described above, a relational expression or a relation table as a line indicating the relation between the degree of powder adhesion and the speed coefficient k of the conveyor belt 21 as shown in FIG. Are prepared and stored in the control device 120.

  Returning to FIG. 4, in step S8, printing on the tablets T on the transport belt 21 is started.

  The tablet T on the conveyance belt 21 is detected by the detection unit 31 for each conveyance path of the tablet T, and a detection signal from the detection unit 31 is input to the control device 120 as a trigger signal. Thereafter, the tablet T on the transport belt 21 is imaged by the imaging unit 51 for each transport path of the tablet T. The upper surface of the tablet T is imaged by the imaging unit 51 at the timing based on the above-described trigger signal, that is, the timing when the tablet T reaches the lower side of the imaging unit 51, and the captured image is transmitted to the image processing device 110.

  Then, based on the pre-printing inspection image transmitted from the imaging unit 51, defect information of the tablet T is generated by the image processing device 110 and transmitted to the control device 120. Based on the defect information of the tablet T, the controller 120 determines whether there is a defect of the tablet T. If it is determined that the defect exists in the tablet T, printing on the tablet T is prohibited. Further, based on the tablet position detection image transmitted from the imaging unit 51, the position information of the tablet T (for example, the position information of the tablet T in the X direction, the Y direction, and the θ direction) is generated by the image processing device 110, It is transmitted to the control device 120. Based on the position information of the tablet T, printing conditions for the tablet T are set by the control device 120.

  After that, the tablet T on the transport belt 21 is printed by the printing device 60 based on the above-described printing conditions at the timing based on the above-described trigger signal, that is, at the timing when the tablet T reaches below the inkjet head 61. . In each inkjet head 61 of the printing apparatus 60, ink is appropriately discharged from each discharge port 61a, and identification information such as characters and marks is printed on the upper surface of the tablet T. The ink applied to the tablet T is rapidly dried at room temperature.

  The tablet T from which the ink has been dried is inspected by the third imaging device 70. That is, the tablet T from which the ink has been dried is captured by the imaging unit 71 for each transport path of the tablet T, and the captured image is transmitted to the image processing apparatus 110. Based on the print state inspection image transmitted from the imaging unit 71, print pattern inspection information is generated by the image processing device 110 and transmitted to the control device 120. Based on the print pattern inspection information, the control device 120 determines whether or not the tablet T can be printed.

  Thereafter, when the tablet T that has been inspected is positioned at the downstream end of the transport belt 21, the tablet T is released from the state held by the transport belt 21, falls from the transport belt 21, and is collected by the collection device 80. At this time, the tablet T that does not have the above-described defect and has passed the inspection of the printing pattern is dropped as it is and is collected by the collecting device 80, but the inspection of the tablet T that has the defect and the printing pattern has failed. The existing tablets T are removed by air blowing during the transportation. In addition, the tablet T excluded by spraying of air is collect | recovered by the other collection container (not shown) provided next to the collection | recovery apparatus 80, for example. In addition, when there are many tablets T that have failed, or tablets T that have failed the inspection of the printing pattern (for example, tablets T that have chipping or tablets T that have failed the inspection of the printing pattern continuously When 10 are detected), the control device 120 determines that a problem has occurred in the tablet printing device 1, stops supplying new tablets T to the transport belt 21, and at this time, places them on the transport belt 21. The existing tablet T is collected and the tablet printing apparatus 1 is stopped. At this time, the tablets T remaining on the conveyor belt 21 are collected in another collection container (not shown) provided next to the collection device 80. As a result, it is possible to prevent the unprinted tablets T from being mixed into the collection device 80 from which non-defective products are collected. Of the tablets T collected in this manner, the unprinted tablets T that are not damaged such as chipping can be reintroduced into the tablet printing apparatus 1.

  In step S9, it is determined whether or not printing of all tablets T has been completed. If it is determined that printing of all tablets T has been completed (YES), imaging of the conveyor belt 21 is stopped in step S10, and the conveyor belt 21 is stopped in step S11. On the other hand, if it is determined that printing of all tablets T has not been completed (NO), the process returns to step S4 described above, and the processes from step S4 are repeated.

  Thus, the printing process of the tablet T is repeated until the printing of all the tablets T is completed. For this reason, as time passes, the powder of the tablet T adhering to the surface M1 of the conveyance belt 21 will accumulate. As the amount of accumulated powder increases and the degree of powder adhesion of the conveyor belt 21 increases, the speed coefficient k of the speed of the conveyor belt 21 is updated to a value corresponding to the increasing degree of powder adhesion in step S7. Is done. In Step S5, if it is determined that the degree of powder adhesion on the conveyor belt 21 is higher than a predetermined value (YES), the supply of the tablets T is stopped in Step S12.

  Next, in step S <b> 13, cleaning of the transport belt 21 is performed by the belt cleaning device 100. First, the belt cleaning apparatus 100 moves so that the cleaning brush 101 contacts the conveying belt 21 with a predetermined pressing force. And the powder adhering to the conveyance belt 21 is removed by the sweeping operation of the cleaning brush 101 and the gas blowing operation by the gas blowing unit 102, and the powder is sucked together with the air by the gas suction unit 103. When the cleaning of the transport belt 21 is completed, the process returns to step S4 again, and the processing from step S4 is repeated.

  In order to accurately measure the position of the tablet T, the black transport belt 21 is often used for the transport belt 21 of a color different from that of the tablet T, for example, the tablets T of each color such as white, light blue, and yellow. . However, since the transport belt 21 sequentially transports a large number of tablets T, the powder of the tablets T accumulates on the surface M1 of the transport belt 21 as the transport is repeated. Thereby, since the surface color of the conveyance belt 21 approaches the color of the tablet T, it is difficult to accurately detect the position of the tablet T from the captured image. Therefore, the powder of the tablet T adhering to the transport belt 21 causes a printing failure. Further, it becomes difficult to hold the tablet T normally due to the influence of the powder, and the tablet T moves during the conveyance, causing a positional deviation or a swing at the time of printing, or dropping from the conveyance belt 21. Sometimes.

  On the other hand, according to the printing process described above, the conveyor belt 21 is cleaned by the belt cleaning device 100 according to the degree of powder adhesion of the conveyor belt 21. Thereby, since it becomes possible to suppress the fall of the position detection precision of the tablet T by the influence of the powder of the tablet T, generation | occurrence | production of a printing defect can be suppressed. Furthermore, since it is possible to suppress a decrease in the holding force of the tablet T due to the influence of the powder of the tablet T, it is possible to suppress misalignment or shaking movement during printing, and more reliably suppress the occurrence of printing defects. .

  In addition, when the surface M1 of the conveyor belt 21 is imaged or when the surface M1 of the conveyor belt 21 is cleaned, each operation is performed with the supply of the tablet T stopped. Thereby, since the tablet T does not interfere with each operation, each operation can be executed accurately. Since it is possible to clean the surface M1 of the transport belt 21 in a state where the tablets T that are the cause of powder generation are not present on the surface of the transport belt 21, the surface M1 of the transport belt 21 is cleaned while transporting the tablets T. As compared with the above, powder can be reliably removed from the surface M1 of the conveyor belt 21.

Further, the control device 120 described above depends on the pressing force by the pressing mechanism 101 a in the belt cleaning device 100, the gas blowing force or the amount sprayed by the gas blowing unit 102, and the gas suction unit 103 according to the degree of powder adhesion of the conveyor belt 21. It is possible to control either the suction force or the suction amount of the gas. For example, the control device 120 increases the pressing force, the gas spray force or spray amount, the gas suction force or suction amount as the powder adhesion degree increases, or decreases as the powder adhesion degree decreases. . It is also possible to change the size of each by appropriately combining the pressing force, the gas spray force and spray amount, and the gas suction force and suction amount. For example, the pressing force is reduced, but the gas blowing force and suction force are increased. Thus, according to the powder adhesion degree of the conveyance belt 21, the cleaning capability of the belt cleaning apparatus 100 can be adjusted suitably.
Further, the speed of the conveyor belt 21 is set according to the degree of powder adhesion with which the powder of the tablet T adheres to the surface M1 of the conveyor belt 21. In particular, the speed of the conveyor belt 21 is set slower as the degree of powder adhesion increases. Therefore, even if the powder of the tablet T adheres to the transport belt 21 and the holding power of the tablet T when transported is reduced, the positional deviation or shaking movement during printing is suppressed, and the occurrence of printing defects is more reliably suppressed. can do.

  As described above, according to the embodiment, the surface M1 on which the tablet T is placed on the transport belt 21 is imaged by the first imaging device 40, and the transport belt 21 is based on the captured image. The image processing apparatus 110 detects the degree of powder adhesion of the tablet T to the surface M1. Since the speed of the conveyor belt 21 is adjusted according to the degree of powder adhesion, even during the period from when the supply of the tablets T is stopped to when the conveyor belt 21 is cleaned, positional deviation or shaking movement during printing can occur. Since it is suppressed, the occurrence of printing defects can be suppressed more reliably. Moreover, although productivity will fall by stopping and cleaning frequently, since the frequency | count of a stop can be reduced and a printing process can be continued, the fall of productivity can be suppressed.

(Other embodiments)
In the above-described embodiment, the speed of the conveyor belt 21 is decreased depending on the degree of powder adhesion of the conveyor belt 21. However, if the speed of the conveyor belt 21 is decreased more than a certain level, the productivity becomes too low and it is better to clean. In some cases, a reduction in final productivity may be suppressed, and the speed of the conveyor belt 21 may be used to determine whether or not cleaning is necessary. In FIG. 5, for example, a state where the above-described speed coefficient k is set to 0.7 is indicated by a two-dot chain line.

  The above-described relationship regarding the speed of the conveyor belt 21 may be an approximate expression based on a value obtained through experiments, a calculated value based on the approximate expression may be used, or a table with values at a certain interval (step) may be used. May be. The value at such an interval is shown by a one-dot chain line in FIG.

  Further, when the degree of powder adhesion is higher than the predetermined value in the above-described step S5, the supply of the tablets T is stopped, and then all the tablets T placed on the transport belt 21 at this time are subjected to a printing process and the collecting device 80. Will be collected. At the same time as the supply of the tablets T is stopped, the printing process is also stopped. At this time, the tablets T that have passed the inkjet head 61 and have been printed and the unprinted tablets T are collected separately. Also good.

  Further, the “timing at which the tablet T does not arrive” is measured from the output from the detection device 30 for determining the arrival of the tablet T, and at this timing, the camera for the pre-printing inspection of the tablet T (the second imaging in the above-described embodiment). The image of the conveyor belt 21 may be taken with the apparatus 50) to check the degree of powder adhesion.

  Further, it is possible to measure the reflectance with a laser displacement meter as the detection unit 31. You may detect the powder adhesion degree of the conveyance belt 21 by the change of this reflectance. When the tablet T is present, the arrival of the tablet T can be detected, and when the tablet T is not present, the reflectance can be measured. Since the resolution of the laser displacement meter is about 1 μm and can always be detected, it is possible to detect the amount of powder on the conveyor belt 21 along with the detection of the tablet T. Note that it is desirable to provide a laser displacement meter so that the laser light strikes a position where the suction hole 21a on the conveyor belt 21 is not detected (for example, right next to the suction hole 21a).

  In addition, although the cleaning timing of the print head 61 is measured by the amount of powder adhering to the conveyor belt 21, it is not limited to this. For example, the determination may be made from the amount of powder accumulated in the belt cleaning device 100. However, the amount of the accumulated powder is the amount of the powder adhering to the conveyance belt 21. Therefore, in either case, the speed of the transport belt 21 is adjusted based on the degree of powder adhesion of the tablet T to the surface M1 of the transport belt 21.

  In addition, although the color density is cited as a criterion for determining the degree of powder adhesion, the present invention is not limited to this, and the degree of powder adhesion may be determined based on the adhesion area of the powder.

  In the above-described embodiment, as an image for detecting the degree of powder adhesion on the conveyor belt 21, the surface M <b> 1 of the conveyor belt 21 at a position where the tablet T downstream of the collection device 80 is not mounted on the conveyor belt 21. However, the present invention is not limited to this. For example, the tablet T is placed on the transport belt 21 between the third imaging device 70 and the collection device 80. It is also possible to pick up an image of the surface M1 of the conveyor belt 21 at the position where it is mounted. However, in order to improve the detection accuracy of the degree of powder adhesion to the surface M1 of the conveyor belt 21, for example, imaging is performed in a state where the tablet T is not in the predetermined imaging field of view, and the image does not include the tablet T. It is desirable to use In addition, when detecting a powder adhesion degree by the image containing the tablet T, it is necessary to make the imaging range of the imaging device used for imaging into the range more than the magnitude | size of a tablet.

  In the above-described embodiment, the powder adhesion degree of the conveyor belt 21 is detected using the image captured by the first imaging device 40. However, the present invention is not limited to this. The degree of powder adhesion of the conveyor belt 21 may be detected using an image captured by the imaging device 50 or the third imaging device 70.

  According to the above-described embodiment, when it is determined that the degree of powder adhesion of the transport belt 21 is higher than a predetermined value, the supply of the tablet T is stopped and the transport belt 21 is cleaned. The inkjet head 61 may be cleaned simultaneously with the cleaning. Thereby, the powder adhering to the discharge port 61a of the inkjet head 61 and the periphery of the discharge port 61a is removed. For this reason, since the powder of the tablet T adheres to the inkjet head 61, clogging of the nozzles, change in the flying direction of the ink, and the like are suppressed, so that occurrence of printing defects can be suppressed. The ink jet head 61 can be cleaned by discharging ink from each discharge hole 61a (dummy discharge) and removing powder and ink adhering to the discharge port 61a. It is also possible to bleed ink from each discharge port 61a of the inkjet head 61 and remove (wiping) the powder and ink adhering to the discharge port 61a and its periphery by wiping with a wiping mechanism. In wiping, a method of scraping with a cloth or a blade may be used, powder or ink may be removed by a vacuum wipe mechanism, or a combination of these may be used. The inkjet head 61 may be periodically cleaned without being cleaned with the transport belt 21, or may be periodically performed in addition to being performed with the cleaning of the transport belt 21.

  In the above-described embodiment, the belt cleaning device 100 is configured by the cleaning brush 101, the gas blowing unit 102, and the gas suction unit 103. However, the present invention is not limited to this, and the cleaning brush 101, the gas blowing unit is used. The belt cleaning device 100 may be configured by only one or two of the gas 102 and the gas suction unit 103.

  Moreover, although the brush roller is used as the cleaning brush 101, it is not restricted to this, For example, you may use the linear brush 201 etc. as shown in FIG. As shown in FIG. 6, the linear brush 201 is provided in the belt cleaning device 200. The belt cleaning device 200 includes a gas suction unit 202 in addition to the linear brush 201. The straight brush 201 is integrated with the gas suction tube 201a, and the powder of the tablet T adhering to the straight brush 201 is sucked into the gas suction tube 201a. Note that the linear brush 201 and the gas suction tube 201a are provided so as to be able to contact and separate from the transport belt 21 by a moving mechanism (not shown), and the degree of pressing of the linear brush 201 against the transport belt 21 can be changed.

  In the above-described embodiment, the cleaning brush 101 rotates in the direction opposite to the traveling direction of the conveyor belt 21. However, the present invention is not limited to this and may not rotate. Alternatively, the cleaning brush 101 may rotate in the same direction as the conveyance belt 21 with a speed difference. That is, the cleaning brush 101 only needs to sweep the surface of the transport belt 21.

  Further, the position of the belt cleaning device 100 is assumed to be below the side of each driven pulley 23 in the transport belt 21, but is not limited to this, as long as it does not interfere with the transport, imaging, and printing of the tablet T. good. For example, even if the belt cleaning device 100 is provided between the third imaging device 70 and the collection device 80, the belt cleaning device 100 is provided so as to be retractable so as not to hinder the conveyance, imaging, and printing of the tablet T. There is no problem if it is evacuated. In the step in which the supply of the tablets T is stopped, the tablets T do not exist on the transport belt 21, so that there is no need to retreat.

  The belt cleaning devices 100 and 200 use roll brushes and linear brushes, but are not limited thereto, and may be wiped with a cloth or an endless roll cloth.

  In the above-described embodiment, the tablet T is illustrated as being transported in two rows. However, the present invention is not limited to this, and the number of rows may be one row, three rows, four rows or more, and is particularly limited. Is not to be done.

  Further, in the above-described embodiment, only one conveyance belt 21 is provided. However, the present invention is not limited to this, and two or more conveyance belts 21 may be provided, and the number is not particularly limited. .

  In the above-described embodiment, the inkjet head 61 is provided for each transport path of the tablets T. However, the present invention is not limited to this. For example, printing on two or more rows of tablets T by one inkjet head 61 is possible. May be performed.

  In the above-described embodiment, the inkjet head 61 is exemplified by the inkjet head in which the discharge ports 61a are arranged in a row. However, the present invention is not limited to this, and for example, an inkjet head in which the discharge ports 61a are arranged in a plurality of rows is used. Anyway. A plurality of inkjet heads may be used side by side along the conveyance direction A1 of the tablet T.

  In the above-described embodiment, the example of performing printing by the inkjet head 61 has been described. However, the present invention is not limited to this, and printing by the printing apparatus 60 may be applied to laser marking or transfer printing using a transfer roller. it can. It is possible to prevent the powder T from adhering to the conveyor belt 21 and the tablet T from being shaken or shifted during conveyance or printing, and the printing failure of the tablet T can be suppressed.

  Moreover, in the above-mentioned embodiment, although printing on the single side | surface of the tablet T was illustrated, it is not restricted to this, For example, the conveying apparatus 20 etc. are piled up and down, and it arrange | positions by the upper conveying apparatus 20 The printed tablet T may be reversed and delivered to the lower conveying device 20 to print both sides of the tablet T.

  In the above-described embodiment, the circular suction hole 21a is exemplified as the hole for holding the tablet T. However, the present invention is not limited to this. For example, a suction hole such as a rectangle, an ellipse, or a slit is provided. It can be used, and the shape of the suction hole 21a is not particularly limited. Moreover, although the through-hole was illustrated as the suction hole 21a, it is not restricted to this. For example, it is also possible to eliminate the suction part 25 and form a concave hole for accommodating the tablet T in the surface M1 of the transport belt 21 instead of the suction hole 21a.

  In the above-described embodiment, the suction part 25 is formed over the outer periphery excluding the part on the side of each driven pulley 23 in the conveyor belt 21. However, the present invention is not limited to this. May be formed over the entire circumference of the conveyor belt 21, and at least the suction portion 25 may be formed between the time when the tablet T is supplied and the time when the tablet T is recovered.

  In the above-described embodiment, the ink printed on the tablet T is exemplified as being naturally dried. However, the present invention is not limited to this. For example, a drying device that dries the tablet T on the conveyor belt 21 after printing is used. It is also possible to provide it. As this drying apparatus, it is possible to use various drying apparatuses such as a heater for drying an object to be dried by radiant heat, or a blower for drying an object to be dried by warm air or hot air.

  In the above-described embodiment, the printing timing is exemplified based on the detection device 30. However, the present invention is not limited to this. For example, the printing timing is determined based on the second imaging device 50. Anyway.

  Here, as the above-mentioned tablet, a tablet used for medicine, food and drink, washing, industrial use or fragrance can be included. In addition, examples of the tablet include a naked tablet (uncoated tablet), a sugar-coated tablet, a film-coated tablet, an enteric tablet, a gelatin-encapsulated tablet, a multilayer tablet, and a dry-coated tablet, and various capsule tablets such as a hard capsule and a soft capsule. Can also be included in the tablet. Furthermore, the shape of the tablet includes various shapes such as a disk shape, a lens shape, a triangle, and an ellipse. In addition, when the tablet to be printed is for medical use or food and drink, edible ink is suitable as the ink to be used. As the edible ink, any of synthetic dye ink, natural dye ink, dye ink, and pigment ink may be used.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Tablet printer 10 Supply apparatus 21 Conveyor belt 40 1st imaging device 50 2nd imaging device 61 Inkjet head 70 3rd imaging device 90 Head cleaning apparatus 100 Belt cleaning apparatus 101 Cleaning brush 102 Gas spray apparatus 103 Gas suction apparatus 110 Image processing device 120 Control device M1 Surface T Tablet

A tablet printing apparatus according to an embodiment of the present invention includes a conveyance belt that conveys tablets, a printing apparatus that performs printing on tablets conveyed by the conveyance belt, and a powder adhesion that detects the degree of powder adhesion of tablets to the surface of the conveyance belt. comprising a detection device, in accordance with the detected powder attaching degree by powder deposition detecting device, and a control device that adjust the speed for conveying the tablets according to the conveyor belt.

A tablet printing method according to an embodiment of the present invention is a tablet printing method in which tablets are transported by a transport belt and printing is performed on the tablets transported by the transport belt, and the tablet powder adhesion degree on the surface of the transport belt is determined. A step of detecting by the powder adhesion detection device, and a step of adjusting a speed at which the tablets are conveyed by the conveyance belt according to the degree of powder adhesion detected by the powder adhesion detection device.

Claims (6)

A transport belt for transporting tablets;
A printing apparatus for printing on the tablets conveyed by the conveyance belt;
A powder adhesion detection device for detecting the degree of powder adhesion of the tablet to the surface of the conveyor belt;
A control device that varies the speed at which the tablets are transported by the transport belt according to the degree of powder adhesion detected by the powder adhesion detection device;
A tablet printing apparatus comprising:   2. The tablet printing apparatus according to claim 1, wherein the control device decreases a speed at which the tablets are transported by the transport belt as the degree of powder adhesion increases. A belt cleaning device for cleaning the surface of the conveyor belt;
2. The tablet printing apparatus according to claim 1, wherein the control device causes the belt cleaning device to perform cleaning of the conveyance belt in accordance with the degree of powder adhesion detected by the powder adhesion detection device. The powder adhesion detector is
An imaging device for imaging the surface of the conveyor belt;
The tablet printing apparatus according to any one of claims 1 to 3, wherein the powder adhesion degree is detected based on an image captured by the imaging apparatus. A tablet printing method for transporting tablets by a transport belt and printing on the tablets transported by the transport belt,
Detecting the degree of powder adhesion of the tablet to the surface of the conveyor belt with a powder adhesion detector;
Varying the speed at which the tablet is conveyed by the conveyor belt according to the degree of powder adhesion detected by the powder adhesion detector;
A tablet printing method comprising:   The tablet printing method according to claim 5, wherein in the step of changing the speed at which the tablets are conveyed by the conveyor belt, the speed is decreased as the degree of powder adhesion increases.

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