Tablet inspection device and tablet printing device

Abstract

To provide a tablet inspection device and a tablet printing device that can improve inspection accuracy and suppress the length of inspection time. [Solution] The tablet inspection apparatus according to the embodiment includes an acquisition unit that acquires a three-dimensional image having height information for each point of a tablet, a storage unit that stores a model image, and a determination unit that compares the three-dimensional image acquired by the acquisition unit with the model image stored in the storage unit and determines defects in the tablet based on the comparison result between the three-dimensional image and the model image. The shape of the tablet is a shape that has rotational symmetry, and the model image is generated by rotating a good product image having height information for each point of a good product tablet multiple times to generate multiple good product images, and then synthesizing the multiple good product images.

Description

Technical Field

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[0001] Embodiments of the present invention relate to a tablet inspection device and a tablet printing device.

Background Art

[0002] In tablet inspection, inspection techniques have been developed to inspect the shape of each of a plurality of sequentially conveyed tablets. In this inspection technique, for example, a three-dimensional image of a tablet is acquired using the optical cutting method, the acquired captured image is compared with a model image, and the presence or absence of defects in the tablet, the position of the defects, etc. are determined based on the difference between the captured image and the model image.

[0003] In such tablet inspection, in order to improve the inspection accuracy for detecting tablet defects, for example, there is a method of improving the quality of the model image used in the inspection. However, to achieve this, a large number (for example, about 200) of images of good-quality tablets that are the source of the model image must be prepared, and the total inspection time including the preparation time increases.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by the present invention is to provide a tablet inspection device and a tablet printing device that can improve inspection accuracy and suppress an increase in inspection time.

Means for Solving the Problems

[0006] The tablet inspection apparatus according to the embodiment includes an acquisition unit that acquires a three-dimensional image having height information for each point of a tablet, a storage unit that stores a model image, and a determination unit that compares the three-dimensional image acquired by the acquisition unit with the model image stored in the storage unit and determines defects in the tablet based on the comparison result between the three-dimensional image and the model image. The shape of the tablet is a rotationally symmetrical shape, and the model image is generated by rotating a good product image having height information for each point of a good product tablet multiple times to generate multiple good product images, and then synthesizing the multiple good product images.

[0007] The tablet printing apparatus according to the embodiment comprises a conveying device for conveying tablets, a tablet inspection device for inspecting tablets conveyed by the conveying device, and a printing device for printing on tablets conveyed by the conveying device. The tablet inspection device comprises an acquisition unit for acquiring a three-dimensional image having height information for each point of the tablet, a storage unit for storing a model image, and a determination unit for comparing the three-dimensional image acquired by the acquisition unit with the model image stored in the storage unit and determining defects in the tablet based on the comparison result between the three-dimensional image and the model image. The shape of the tablet is a shape with rotational symmetry, and the model image is generated by rotating a good product image having height information for each point of a good product tablet multiple times to generate multiple good product images, and then synthesizing the multiple good product images. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of an example configuration of a tablet printing apparatus according to an embodiment. [Figure 2] This is a plan view of an example configuration of a printing apparatus according to an embodiment. [Figure 3] This is a first schematic diagram of the three-dimensional image acquisition unit according to the embodiment. [Figure 4] This is a second schematic diagram of the three-dimensional image acquisition unit according to the embodiment. [Figure 5] This is an explanatory diagram of the composite image generation according to the embodiment. [Figure 6]This is a detailed explanatory diagram of the first composite image generation according to the embodiment. [Figure 7] This is a detailed first explanatory diagram of the generation of the second composite image according to the embodiment. [Figure 8] This is a detailed second explanatory diagram of the second composite image generation according to the embodiment. [Figure 9] These are explanatory diagrams illustrating the three-dimensional shapes of the tablets in a single image of a good product and a composite image according to the embodiment. [Figure 10] This is an explanatory diagram illustrating the height difference between the captured image and the composite image based on the captured image according to the embodiment. [Figure 11] This is an explanatory diagram illustrating the height difference between the composite image and the captured image, based on the composite image according to the embodiment. [Modes for carrying out the invention]

[0009] <Embodiment> Embodiments will be described with reference to Figures 1 to 11.

[0010] (Basic configuration) As shown in Figure 1, the tablet printing apparatus 1 according to this embodiment comprises a supply device 10, a first printing device 20, a second printing device 30, a recovery device 40, and a control device 50.

[0011] The first printing device 20 and the second printing device 30 have essentially the same structure. The components of the tablet printing device 1, namely the supply device 10, the first printing device 20, the second printing device 30, and the collection device 40, are arranged in this order. The tablets T are transported in this order while a series of processes of supply, printing, and collection are carried out. The path through which the tablets T are transported is called the transport path P. That is, the upstream end of the transport path P is the supply device 10 side, and the downstream end is the collection device 40 side. In this embodiment, two parallel transport paths P are formed.

[0012] The supply device 10 includes a hopper 11, an alignment feeder 12, and a transfer feeder 13. This supply device 10 is configured to supply tablets T to be printed to a first printing device 20 and is located on one end of the first printing device 20. The hopper 11 holds a large number of tablets T and sequentially supplies the tablets T to the alignment feeder 12. The alignment feeder 12 aligns the supplied tablets T in two rows and transports them toward the transfer feeder 13 in the direction of arrow A1 in Figure 1 (clockwise). The transfer feeder 13 sequentially sucks up and holds each tablet T arranged in two rows on the alignment feeder 12 from the top of the tablet T, and transports each held tablet T toward the first printing device 20 in two rows in the direction of arrow A2 in Figure 1 (counterclockwise) to deliver it to the first printing device 20. This supply device 10 is electrically connected to a control device 50, and its drive is controlled by the control device 50. For example, a belt conveying mechanism can be used as the alignment feeder 12 and the transfer feeder 13.

[0013] The first printing apparatus 20 comprises a first transport device 21, a first detection device 22, a first imaging device 23, a first three-dimensional image acquisition device 3Da, a first print head device 24, a second imaging device 25, and a first drying device 26.

[0014] The first conveying device 21 has a conveyor belt 21a, a driving pulley 21b, a plurality of driven pulleys 21c (three in the example of FIG. 1), a motor 21d, a position detector 21e, and a suction chamber 21f. The conveyor belt 21a is an endless belt and is stretched over the driving pulley 21b and each driven pulley 21c. The driving pulley 21b and each driven pulley 21c are rotatably provided on the apparatus main body, and the driving pulley 21b is connected to the motor 21d. The motor 21d is electrically connected to the control device 50, and its driving is controlled by the control device 50. The position detector 21e is a device such as an encoder and is attached to the motor 21d. This position detector 21e is electrically connected to the control device 50 and transmits a detection signal to the control device 50. The control device 50 can obtain information such as the position, speed, and movement amount of the conveyor belt 21a based on the detection signal. This first conveying device 21 rotates the conveyor belt 21a together with each driven pulley 21c by the rotation of the driving pulley 21b by the motor 21d, and conveys the tablets T on the conveyor belt 21a in the conveying direction A1 (clockwise direction), which is the direction of the arrow A1 in FIG. 1.

[0015] On the surface of the conveyor belt 21a, as shown in FIG. 2, a plurality of circular suction holes 21g are formed. Each of these suction holes 21g is a through-hole for adsorbing the tablet T to the surface of the conveyor belt 21a, and is arranged in two parallel rows along the conveying direction A1 so as to form two conveying paths P. Each suction hole 21g is connected to the inside of the suction chamber 21f through a suction path formed in the suction chamber 21f, and it is possible to obtain a suction force by the suction chamber 21f. An intake device such as a pump is connected to the suction chamber 21f through an intake pipe (both not shown), and the inside of the suction chamber 21f is depressurized by the operation of the intake device. The intake pipe is connected to the substantially center of the side surface of the suction chamber 21f (a surface parallel to the conveying direction A1). Further, the intake device is electrically connected to the control device 50, and its driving is controlled by the control device 50.

[0016] The first detection device 22 has a plurality of detection units 22a (two in the example of FIG. 2). The detection units 22a are arranged one by one for each conveyance path P on the downstream side in the conveyance direction A1 from the position where the tablets T on the conveyance belt 21a are supplied by the supply device 10 and in a direction (for example, a direction perpendicular) intersecting the conveyance direction A1 in the horizontal plane, and are provided above the conveyance belt 21a. The detection unit 22a detects the position of the tablet T on the conveyance belt 21a (the position of the tablet T in the conveyance direction A1) by transmitting and receiving laser light, and functions as a trigger sensor for each device located downstream. As the detection unit 22a, various laser sensors such as a reflection type laser sensor can be used. Each detection unit 22a is electrically connected to the control device 50 and transmits a detection signal to the control device 50.

[0017] The first imaging device 23 has a plurality of imaging units 23a (two in the example of FIG. 2). The imaging units 23a are arranged one by one for each conveyance path P on the downstream side in the conveyance direction A1 from the position where the first detection device 22 is provided and in a direction (for example, a direction perpendicular) intersecting the conveyance direction A1 in the horizontal plane, and are provided above the conveyance belt 21a. This imaging unit 23a performs imaging at the timing when the tablet T reaches directly below the imaging unit 23a based on the above-described position information of the tablet T, acquires an image including the upper surface of the tablet T, and transmits the acquired image to the control device 50. As the imaging unit 23a, various cameras having imaging elements such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) can be used. Each imaging unit 23a is electrically connected to the control device 50, and their driving is controlled by the control device 50. In addition, illumination for imaging is provided as necessary.

[0018] The first three-dimensional image acquisition device 3Da has a plurality of three-dimensional image acquisition units 3D1 (two in the example of FIG. 2). The three-dimensional image acquisition unit 3D1 is arranged one by one for each conveyance path P on the downstream side in the conveyance direction A1 from the position where the first imaging device 23 is provided and in a direction (for example, a direction perpendicular) intersecting the conveyance direction A1 in the horizontal plane, and is provided above the conveyance belt 21a.

[0019] As shown in Figures 3 and 4, the three-dimensional image acquisition unit 3D1 comprises a laser beam irradiation unit L1 and a three-dimensional imaging camera C1, and further comprises an image processing unit 51 (see Figure 1). Figure 3 is a view of the three-dimensional image acquisition unit 3D1 from the upstream side of the transport direction A1, and Figure 4 is a view of the three-dimensional image acquisition unit 3D1 from a direction perpendicular to the transport direction A1. The laser beam irradiation unit L1 irradiates a band-shaped laser beam. The three-dimensional imaging camera C1 images the surface of the tablet T irradiated with the laser beam. The image processing unit 51 controls the laser beam irradiation unit L1 and the three-dimensional imaging camera C1 and processes the image captured by the three-dimensional imaging camera C1. As shown in Figure 3, the laser beam irradiation unit L1 irradiates from directly above the transport belt 21a so that the irradiation line of the band-shaped laser beam irradiated onto the transport belt 21a is perpendicular to the transport direction A1. As shown in Figure 4, the three-dimensional imaging camera C1 is located downstream of the laser beam irradiation unit L1 in the transport direction A1 and captures an image of the tablet T on the transport belt 21a from diagonally above the tablet T. The image captured by the three-dimensional imaging camera C1 is sent to the control device 50 (see Figure 1), where it is processed by the image processing unit 51 to obtain a three-dimensional image. By analyzing this three-dimensional image, the three-dimensional shape of the tablet T is detected (so-called light section method).

[0020] Returning to Figure 2, the first print head device 24 has multiple inkjet print heads 24a (two in the example of Figure 2). The print heads 24a are arranged one by one along each transport path P downstream of the position where the first three-dimensional image acquisition device 3Da is installed, in a direction that intersects the transport direction A1 in the horizontal plane (for example, perpendicular to it), and are installed above the transport belt 21a. Each print head 24a has multiple nozzles 24b, and ink is ejected individually from these nozzles 24b. The print head 24a is installed such that the alignment direction of the nozzles 24b intersects the transport direction A1 in the horizontal plane (for example, perpendicular to it). Various known inkjet print heads can be used as the print heads 24a. Each print head 24a is electrically connected to the control device 50, and their drive is controlled by the control device 50.

[0021] The second imaging device 25 has multiple imaging units 25a (two in the example in Figure 2). The imaging units 25a are arranged one by one for each transport path P downstream of the position where the first print head device 24 is located in the transport direction A1, and in a direction that intersects the transport direction A1 in the horizontal plane (for example, a direction perpendicular to it), and are located above the transport belt 21a. Based on the position information of the tablet T described above, the imaging unit 25a takes an image when the tablet T reaches directly below the imaging unit 25a, acquires an image including the top surface of the tablet T (an image for inspection), and transmits the acquired image to the control device 50. Similar to the imaging unit 23a described above, various cameras having image sensors such as CCD or CMOS can be used as the imaging unit 25a. Each imaging unit 25a is electrically connected to the control device 50, and their drive is controlled by the control device 50. Illumination for imaging is also provided as needed.

[0022] Returning to Figure 1, the first drying device 26 is located downstream in the transport direction A1 from the location where the first print head device 24 is installed, for example, below the first transport device 21. This first drying device 26 is a device common to both rows of transport paths P and dries the ink applied to each tablet T on the transport belt 21a. Various drying units can be used for the first drying device 26, such as a blower that dries using a gas such as air, a heater that dries using radiant heat, or a blower that dries using warm air or hot air by using both gas and a heater. The first drying device 26 is electrically connected to the control device 50, and its drive is controlled by the control device 50.

[0023] The tablets T that have passed over the first drying device 26 are transported by the movement of the conveyor belt 21a and reach a position near the end of each driven pulley 21c in the first conveying device 21. At this position, the suction force on the tablets T ceases, and the tablets T are released from being held by the conveyor belt 21a and transferred from the first printing device 20 to the second printing device 30.

[0024] The second printing apparatus 30 comprises a second transport device 31, a second detection device 32, a third imaging device 33, a second print head device 34, a fourth imaging device 35, a second three-dimensional image acquisition device 3Db, and a second drying device 36. The second transport device 31 includes a transport belt 31a, a drive pulley 31b, a plurality of driven pulleys 31c (three in the example in Figure 1), a motor 31d, a position detector 31e, and a suction chamber 31f. Each element constituting the second printing apparatus 30 has basically the same structure as the corresponding component in the first printing apparatus 20 described above. The transport direction of the second printing apparatus 30 is the transport direction A2 (counterclockwise direction), which is the direction of arrow A2 in Figure 1.

[0025] The recovery device 40 is located downstream in the transport direction A2 from the location where the second drying device 36 is installed. The recovery device 40 recovers defective tablets T using a defective product recovery device (not shown) and recovers good tablets T using a good product recovery device (not shown).

[0026] The control device 50 comprises an image processing unit 51, a printing processing unit 52, an inspection processing unit 53, and a storage unit 54. The image processing unit 51 processes images. The printing processing unit 52 performs printing-related processing. The inspection processing unit 53 performs inspection-related processing. The storage unit 54 stores various information such as processing information and various programs. This control device 50 controls the supply device 10, the first printing device 20, the second printing device 30, and the collection device 40. The control device 50 also receives position information of tablets T transmitted from the first detection device 22 and the second detection device 32, as well as images transmitted from the individual three-dimensional imaging cameras C1 of the first imaging device 23, the second imaging device 25, the third imaging device 33, the fourth imaging device 35, the first three-dimensional image acquisition device 3Da, and the second three-dimensional image acquisition device 3Db. The operating conditions are set in advance and stored in the storage unit 54. The control device 50 controls each processing unit and the like based on the operating conditions stored in the memory unit 54.

[0027] The control device 50 may be a computer such as a CPU (Central Processing Unit), MCU (Micro Controller Unit), or MPU (Micro Processor Unit). Each part of the control device 50 may be implemented by hardware, software, or both. The storage unit 54 may be a semiconductor memory element such as RAM (Random Access Memory) or flash memory, or a storage device such as a hard disk or optical disc.

[0028] (Generating model images used for tablet shape inspection) Next, we will describe the generation of model images used for shape inspection of the tablet T according to the embodiment.

[0029] The first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db each acquire a three-dimensional image of the tablet T. The storage unit 54 pre-stores a model image to be used for shape inspection. The inspection processing unit 53 compares the three-dimensional image of the tablet T acquired by the first three-dimensional image acquisition device 3Da or the second three-dimensional image acquisition device 3Db with the model image stored in the storage unit 54, and determines defects in the tablet T based on the comparison result between the three-dimensional image and the model image. The first three-dimensional image acquisition device 3Da or the second three-dimensional image acquisition device 3Db, the storage unit 54, and the inspection processing unit 53 are examples of a tablet inspection device, and the inspection processing unit 53 is an example of a determination unit and a generation unit.

[0030] As shown in Figure 5, the inspection processing unit 53 generates good product images E1, E2, etc. for each predetermined angle by rotating the good product image E0 multiple times, for example at predetermined angles, and generates a composite image E by combining the multiple good product images E0, E1, E2, etc. This composite image E is pre-stored in the storage unit 54 as a model image. The good product image E0 is an image that includes height information of a good tablet for each point (e.g., pixel). The height information of a good tablet is, for example, the height information in the Z-axis direction from the upper surface of the conveyor belt 21a to the upper surface of the tablet T placed on the upper surface of the conveyor belt 21a. A point is defined in a coordinate system such as the XYZ coordinate system. For example, the planar position of a point is defined in the XY coordinate system, and the height position of a point is defined in the Z coordinate system. The good product image E0 is rotated within the plane of the XY coordinate system. In other words, in this embodiment, since the planar shape of tablet T is circular, the distribution of points in the XY coordinate system is circular (a shape with rotational symmetry), and the good product image E0 is rotated around its center. The composite image E is generated by combining the original good product image E0 with good product images E1, E2, etc., at predetermined angles. Therefore, the composite image E is an image with more points (height information) than the good product image E0, i.e., an image with higher resolution. The predetermined angles are set in advance, for example, according to the shape of tablet T. The good product image E0 and the good product images E1, E2, etc., at predetermined angles are stored in the storage unit 54 as appropriate.

[0031] The good product image E0 used for model image generation is acquired when a tablet T, i.e., a good product, whose three-dimensional shape is within an acceptable range (i.e., a good product), is fed into the tablet printing device 1, and while the tablet T is placed on the first transport device 21 (and the second transport device 31) and transported, it is captured by both or one of the first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db. When the good product image E0 is acquired by the tablet printing device 1, printing is not performed on the good product tablet, but this is not limited to this. For example, printing may be performed on the good product tablet when the good product image E0 is acquired by the tablet printing device 1. However, it is desirable that printing is not performed on the good product tablet when the good product image E0 is acquired. Furthermore, if a good product image E0 is acquired by both the first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db, the composite image E generated from the good product image E0 acquired by the first three-dimensional image acquisition device 3Da and the composite image E generated from the good product image E0 acquired by the second three-dimensional image acquisition device 3Db are each stored in the storage unit 54 in an identifiable manner.

[0032] Furthermore, the inspection processing unit 53 can generate model images of various resolutions from the composite image E. In the example shown in Figure 5, a low-resolution model image Ea can be generated by reducing the resolution (resolution 0.1 mm), or a high-resolution model image Eb can be generated by increasing the resolution (resolution 0.05 mm).

[0033] As shown in Figure 6, the good product image E0 is point cloud data that includes height information for each point, i.e., height information (three-dimensional information) of the point cloud. This good product image E0 is rotated by a predetermined angle. In the example in Figure 6, one point in the point cloud is at the rotation center of the good product image E0, and the predetermined angle is 10 degrees. The single point that becomes the rotation center is located at the center of the planar shape (e.g., a circle) of the tablet T. By rotating and combining the good product image E0 in this way, a composite image E is generated. The number of points in the composite image E is greater than that of the good product image E0, and the resolution of the composite image E is higher than that of the good product image E0.

[0034] The shape of tablet T (for example, its planar shape) is a shape that exhibits rotational symmetry. Rotational symmetry is the property that when a figure is rotated by a predetermined angle around its center (the planar shape of tablet T), the figure remains the same before and after the rotation (the property that when a figure is rotated 360 degrees, it overlaps with itself (the figure at 0 degrees) two or more times). Let n be an integer of 2 or more, and when a figure is rotated (360 / n) degrees around its center (the center of rotation), the figure overlaps with itself. This property is called n-th time symmetry, n-relational symmetry, or (360 / n) degree symmetry. For example, when n is 3, when a figure is rotated 120 degrees, the figure overlaps with itself. This property is called 3-th time symmetry. Two-dimensional figures include, for example, a circle (n-th time symmetry), a regular n-gon (n-th time symmetry), or a parallelogram (2-th time symmetry). The center of rotation for all of these is the center of the figure.

[0035] As shown in Figure 7, the good product image E0 is point cloud data containing point cloud height information (three-dimensional information), similar to Figure 6. This good product image E0 is rotated by a predetermined angle. In the example in Figure 7, the rotation center of the good product image E0 is a point other than a point in the point cloud, and the predetermined angle is 10 degrees. The rotation center is the center of the planar shape (e.g., a circle) of the tablet T. By rotating and combining the good product image E0 in this way, a composite image Ec is generated. The number of points in the composite image Ec is greater than that of the good product image E0, and the resolution of the composite image Ec is higher than that of the good product image E0. Furthermore, the resolution of the composite image Ec shown in Figure 7 is higher than that of the composite image E shown in Figure 6, even though the resolution of the good product image E0 and the predetermined angle (i.e., the number of rotations and composite images) are the same.

[0036] Figure 8 illustrates the process of combining images while rotating the good product image E0 shown in Figure 7 at predetermined angles of 10 degrees each time. As shown in Figure 8, when the good product image E0 in Figure 7 is rotated by 10 degrees, the good product image E1 rotated by 10 degrees is combined with the good product image E0, generating the combined images E0~E1. When the good product image E0 is rotated by 20 degrees, the good product image E2 rotated by 20 degrees is combined with the combined images E0~E1, generating the combined images E0~E2. This process is repeated. When the good product image E0 is rotated by 80 degrees, the good product image E8 rotated by 80 degrees is combined with the combined images E0~E7, generating the combined images E0~E8. The same process is then performed until the good product image E0 is rotated 360 degrees.

[0037] Note that the rotation center of the good image E0 (point cloud data) does not coincide with one of the points that make up the point cloud, but is not limited to this. For example, the rotation center of the good image E0 (point cloud data) may coincide with one of the points that make up the point cloud. However, for example, as shown in Figure 6, if point cloud data is combined while rotating it around one of the points in the point cloud, even though 36 points of point cloud data (360 degrees) are combined in 10-degree increments, the image obtained will only have the same resolution as when point cloud data rotated only 90 degrees (i.e., 9 points) are combined. Therefore, in order to increase the amount of height information data, it is desirable that the rotation center of the good image E0 does not coincide with one of the points that make up the point cloud.

[0038] Furthermore, in the examples of Figures 7 and 8, the rotation of the good product image E0 results in multiple points extending beyond the circle representing the planar shape of the tablet T. These points are unnecessary for shape inspection of the tablet T. Therefore, the inspection processing unit 53 deletes these points that extend beyond the circle representing the planar shape of the tablet T. This allows for the acquisition of an accurate composite image E. The deletion of points extending beyond the circle may be performed, for example, after each 10-degree composite, or after the completion of all 360-degree composites.

[0039] As shown in Figure 9, the three-dimensional shape T2 based on the model image (composite image E) of tablet T contains more points, i.e., more height information, than the three-dimensional shape T1 based on the good product image E0 of tablet T. This model image of three-dimensional shape T2 is used to inspect the shape of tablet T. Normally, a high-precision, i.e., high-quality model image would be created by preparing a large number of good product tablet images and combining them. However, according to this embodiment, a pseudo-high-quality model image (composite image E) can be created by rotating a single good product tablet image (good product image E0) multiple times and incorporating it.

[0040] Furthermore, if data of good product images E0 of various tablets T have been accumulated to date (for example, a good product image database), then high-quality model images (composite images E) can be created for each type of tablet T using this accumulated data. Therefore, it is possible to utilize the accumulated data of good product images E0 of various tablets T, and high-quality model images can be easily obtained.

[0041] The predetermined angle for rotating the good image E0 is, for example, 10 degrees, but is not limited to this. The predetermined angle for rotating the good image E0 is preferably in the range of 7 to 13 degrees, or preferably a prime number. Alternatively, it is preferable that the angle obtained by adding the predetermined angle for the number of rotations is not exactly 360 degrees. In other words, it is preferable to set the predetermined angle as such that the overlap of point clouds (i.e., points that overlap at the same coordinates within point clouds with different rotation angles) is minimized when comparing the good image E0 before rotation with the good images E1, E2, etc. after rotation.

[0042] Furthermore, while the predetermined angle at which the good product image E0 is rotated is constant, it is not limited to this. For example, the predetermined angle at which the good product image E0 is rotated may be changed during one rotation of the good product image E0. In other words, the good product image E0 may be rotated by multiple different predetermined angles, rather than a constant predetermined angle. For example, the good product image E0 may be rotated by repeatedly switching between predetermined angles of 7 degrees and 13 degrees. In this way, by rotating the good product image E0 while switching between multiple different predetermined angles, rather than a constant predetermined angle, and combining this data, it is possible to generate a good product model image with more evenly distributed height information. For example, if the good product image E0 is rotated by a constant predetermined angle, there is a possibility that a striped pattern (moire phenomenon) may occur in the combined data. However, this can be prevented by rotating the good product image E0 while switching between multiple different predetermined angles. Alternatively, the good product image E0 may be rotated by multiple random angles, rather than a predetermined angle.

[0043] Furthermore, while the image of good product E0 and all the data of good product images E1 to E36 for each predetermined angle are combined, this is not limited to this. For example, only a predetermined number of data from all the data may be combined, or multiple data other than the original good product image E0 may be combined from all the data.

[0044] Furthermore, if the tablet T has a score line, the points (height information) corresponding to the score line may be removed from the good product image E0 (point cloud data). For example, it is desirable to remove the points corresponding to the score line from the good product image E0 and then rotate the good product image E0. Alternatively, the area corresponding to the score line may be separated from the other area, and the area corresponding to the score line may be inspected separately, while the other area may be inspected using the generated model image.

[0045] Using the model image obtained as described above, we will perform a three-dimensional image inspection of tablet T. The specific inspection process will be described later.

[0046] (Printing process and inspection process) Next, the printing and inspection processes performed by the aforementioned tablet printing device 1 will be described. In the following printing process, we will describe double-sided printing, which prints identification information on both sides of the tablet T.

[0047] First, various information, such as print data required for printing, is stored in the storage unit 54 of the control device 50. Then, when a large number of tablets T to be printed are loaded into the hopper 11 of the supply device 10, the tablets T are sequentially supplied from the hopper 11 to the alignment feeder 12, where they are arranged in two rows and moved. These tablets T moving in two rows are sequentially supplied to the conveyor belt 21a of the first 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. As a result, the tablets T supplied onto the conveyor belt 21a are arranged in two rows on the conveyor belt 21a and transported at a predetermined speed. The conveyor belt 31a also rotates in the conveying direction A2 by the rotation of the drive pulley 31b and each driven pulley 31c by the motor 31d.

[0048] In the first printing device 20, the tablets T are held by suction on the conveyor belt 21a, and the tablets T on the conveyor belt 21a are detected by the first detection device 22. As a result, the position information of the tablets T (position in the conveyor direction A1) is acquired and input to the control device 50. This position information of the tablets T is stored in the storage unit 54 and used in post-processing.

[0049] Next, the tablet T on the conveyor belt 21a is imaged by the first imaging device 23 at a timing based on the position information of the tablet T mentioned above, and the image is transmitted to the control device 50. Based on the image transmitted from the first imaging device 23, positional displacement information of the tablet T (for example, the positional displacement of the tablet T in the X, Y, and θ directions in Figure 2) is generated by the image processing unit 51 and stored in the storage unit 54. Based on this positional displacement information of the tablet T, printing conditions for the tablet T (for example, ink ejection position and ejection speed) are set by the printing processing unit 52 and stored in the storage unit 54. In addition, based on the image transmitted from the first imaging device 23, the quality of the appearance of the tablet T is determined by the inspection processing unit 53, and inspection result information indicating the quality of the appearance, such as cracks, chips, and stains, is stored in the storage unit 54. For example, a tablet T that is determined to have a poor appearance is designated as a defective tablet T, and subsequent printing processing is not performed on defective tablets T.

[0050] Next, the tablet T on the conveyor belt 21a is imaged by the three-dimensional imaging camera C1 of the first three-dimensional image acquisition device 3Da, capturing its external shape. The image captured by the three-dimensional imaging camera C1 is transmitted to the control device 50, where it is processed by the image processing unit 51 to generate a three-dimensional image. Based on this three-dimensional image, the inspection processing unit 53 determines whether the tablet T has defects (e.g., shape defects), i.e., whether the tablet T is a defective product, and whether the tablet T has a poor orientation, i.e., whether it is a reusable product. As a result, good tablets T are subjected to subsequent printing, while defective and reusable tablets T are not. Furthermore, based on the three-dimensional image, it is possible to determine the degree of inclination of the upper surface of the tablet T on the conveyor belt 21a from the height information of each point, and thus the orientation of the tablet T can be determined.

[0051] Furthermore, in determining poor posture, images transmitted from the first imaging device 23 may be used in addition to the three-dimensional image. Also, the determination of poor posture may not be performed in the first three-dimensional image acquisition device 3Da, but in the first imaging device 23. In this case, the determination of poor posture is performed in the first imaging device 23 based on the images transmitted from the first imaging device 23.

[0052] Subsequently, when a good tablet T on the conveyor belt 21a reaches the position of the tablet T as described above, based on the timing determined by the position information of the tablet T, that is, when the tablet T reaches below the first print head device 24, printing is performed on the tablet T by the first print head device 24 based on the printing data and printing conditions described above. Ink is appropriately ejected from each nozzle 24b of the print head 24a of the first print head device 24, and identification information such as characters (e.g., alphabet, katakana, numbers) or marks (e.g., symbols, figures) is printed on the upper surface of the tablet T.

[0053] Tablets T on which identification information is printed are imaged by a second imaging device 25 at a timing based on the position information of the tablet T, and the captured images are transmitted to a control device 50. Based on the individual images transmitted from the second imaging device 25, the image processing unit 51 generates print position information indicating the printing position of the print pattern for each tablet T and stores it in the storage unit 54. Based on this print position information, the inspection processing unit 53 determines whether the print quality of the tablet T is good or bad, and inspection result information indicating whether the print quality of each tablet T is good or bad is stored in the storage unit 54. For example, the inspection processing unit 53 determines whether the print pattern is printed in a predetermined pattern at a predetermined position on the tablet T. Tablets T that are determined not to have the print pattern printed in a predetermined pattern at a predetermined position on the tablet T are considered defective tablets that have failed inspection, and no further printing is performed on them.

[0054] The tablet T, having passed below the second imaging device 25, is transported along with the movement of the transport belt 21a and passes above the first drying device 26, which is in the process of drying. At this time, the ink that reaches (impacts) the tablet T is dried by the first drying device 26 as the tablet T passes above it. The ink-dried tablet T is then transported along with the movement of the transport belt 21a and is positioned near the end of the transport belt 21a on the side of each driven pulley 21c. At this position, the suction force on the tablet T ceases, and the tablet T is released from being held on the underside of the transport belt 21a and is passed from the first printing device 20 to the second printing device 30.

[0055] In the second printing device 30, the tablets T are held by suction on the conveyor belt 31a, and printing and inspection processes are performed in the same manner as described above. In the second printing device 30, after being imaged by the third imaging device 33, the tablets T pass below the second three-dimensional image acquisition device 3Db. The tablets T are conveyed along with the movement of the conveyor belt 31a and pass above the second drying device 36, which is in the process of drying. The tablets T, once the ink has dried, reach the defective product collection device. At this position, tablets T other than good products (defective or unknown products) are dropped from the underside of the conveyor belt 31a by a gas injection (blow) from an injection nozzle (not shown) and collected by a storage box (not shown). In addition, reused tablets T that were not printed due to reasons such as poor posture are collected by a reused product collection device (not shown). Tablets T that are not collected by the defective product collection device and the reusable product collection device, i.e., good tablets T, pass over the defective product collection device and the reusable product collection device and reach a position near the end of each driven pulley 31c on the conveyor belt 31a. At this position, the suction action on the tablets T ceases and they fall. Furthermore, gas is blown onto the tablets T from above by a gas blowing part (not shown), so the tablets T reliably fall from the conveyor belt 31a. The tablets T that fall from the conveyor belt 31a are collected in a storage box (not shown).

[0056] Furthermore, the first three-dimensional image acquisition device 3Da is provided upstream of the first print head device 24, and the second three-dimensional image acquisition device 3Db is provided upstream of the second print head device 34. Both are provided so as to face the tablets T being transported on a horizontal plane, rather than on the curved surfaces of the drive pulleys 21b, 31b and the driven pulleys 21c, 31c. This allows for accurate detection of the three-dimensional shape of the tablets T as they are transported on a horizontal plane. Alternatively, the first three-dimensional image acquisition device 3Da may be provided downstream of the first print head device 24, and the second three-dimensional image acquisition device 3Db may be provided downstream of the second print head device 34, both so as to face the tablets T being transported on a horizontal plane. In this case, even if the tablet T collides with the first or second print head device 24 or second print head device 34 as it passes beneath them, causing chipping or cracking, the chipping or cracking can be detected by the first three-dimensional image acquisition device 3Da, and the tablet T containing the chipping or cracking can be discharged as a defective product. Furthermore, because the tablet T is transported on a horizontal plane, its three-dimensional shape can be accurately detected.

[0057] Furthermore, if the nozzle 24b of the first print head device 24 dries out, the ink near the nozzle 24b may solidify due to drying, which can lead to ejection failure. To prevent this, the suction force applied to the suction hole 21g on the conveyor belt 21a facing the first print head device 24 may be reduced to prevent the nozzle 24b from being affected by the airflow. For example, a shielding plate that blocks a part of the suction hole 21g is provided on the upper surface of the suction chamber 21f to reduce the suction force acting below the first print head device 24. Since the suction force applied to the tablet T being conveyed in this area is reduced, a strong suction force will not act on a part of the tablet T, and if the tablet T has an R shape, the possibility of it being held in an upright position is reduced. Preferably, the area in which the suction force is reduced includes not only directly below the first print head device 24, but also from below the first detection device 22 to below the second imaging device 25. This makes it possible to detect, image, and print the tablet T while maintaining the same posture. Furthermore, in the first three-dimensional image acquisition device 3Da, it becomes possible to suppress the tablet T from assuming the upright posture described earlier, thus enabling accurate acquisition of the tablet T's external shape.

[0058] (Calculating height difference) Next, we will explain the height difference between the captured image and the model image based on the embodiment, and the height difference between the model image and the captured image based on the model image.

[0059] In the height difference between the captured image and the model image, as shown in Figure 10, the model image (composite image E) is subtracted from the captured image to obtain a difference image. Whether or not this difference image is within an acceptable range is used to determine whether or not tablet T is a good product. In the example in Figure 10, the height Z2 of point F11 is subtracted from the height Z2 of point F21, resulting in a difference of 0. The height Z3 of point F22 is subtracted from the height Z1 of point F12, resulting in a difference of Z1-Z3. The height Z2 of point F23 is subtracted from the height Z2 of point F13, resulting in a difference of 0.

[0060] In the case of the height difference between the model image and the captured image based on the model image, as shown in Figure 11, the captured image is subtracted from the model image (composite image E) to obtain a difference image. Whether or not this difference image is within an acceptable range is used to determine whether or not tablet T is a good product. In the example in Figure 11, the height Z2 of point F11 is subtracted from the height Z2 of point F21, resulting in a difference of 0. The height Z3 of point F24 is subtracted from the height Z2 of point F11, resulting in a difference of Z3-Z2. The height Z3 of point F22 is subtracted from the height Z1 of point F12, resulting in a difference of Z3-Z1. The height Z2 of point F25 is subtracted from the height Z1 of point F12, resulting in a difference of Z2-Z1.

[0061] Thus, by taking the difference between the model image and the captured image based on the model image (see Figure 11), the number of candidate points to compare increases compared to taking the difference between the captured image and the model image based on the captured image (see Figure 10), thus improving inspection accuracy.

[0062] As described above, the tablet printing apparatus 1 according to this embodiment includes a tablet inspection apparatus. The tablet inspection apparatus includes an acquisition unit (for example, one or both of a first three-dimensional image acquisition device 3Da and a second three-dimensional image acquisition device 3Db) that acquires a three-dimensional image of a tablet T, a storage unit 54 that stores a model image, and a determination unit (for example, an inspection processing unit 53) that compares the three-dimensional image acquired by the acquisition unit with the model image stored in the storage unit 54 and determines defects in the tablet T based on the comparison result between the three-dimensional image and the model image. The shape of the tablet T is a shape that has rotational symmetry, and the model image is generated by rotating a good product image E0, which has height information of a good product tablet for each point, multiple times to generate multiple good product images (for example, each good product image E1 to E36), and then combining the multiple good product images (for example, each good product image E0 to E36). This eliminates the need to prepare a large number of images (e.g., around 200) of good quality tablets to serve as the basis for the model image. A high-quality, appropriate model image is generated from a single good quality image E0, and this appropriate model image is used for inspection. Therefore, inspection time can be reduced and inspection accuracy can be improved.

[0063] <Other Embodiments> In the above description, printing is performed on tablets T using the tablet printing apparatus 1 (tablet printing method) according to the embodiment. However, this can also be rephrased as "printing is performed on tablets T using the tablet printing apparatus 1 (tablet printing method) according to the embodiment to manufacture printed tablets T." In other words, the tablet printing apparatus 1 can be replaced with a tablet manufacturing apparatus, and the tablet printing method can be replaced with a tablet manufacturing method.

[0064] Furthermore, although the above explanation exemplified the transport of tablets T in two rows, the number of rows of tablets T may be one, three, four or more, and the number of transport paths P and the number of transport belts 21a and 31a are not particularly limited. Also, the shape of the suction holes 21g of the transport belts 21a and 31a is not particularly limited.

[0065] Furthermore, although the above explanation exemplified the provision of a print head 24a for each transport path P, the explanation is not limited to this, and printing may be performed on two or more rows of tablets T using a single print head 24a.

[0066] Furthermore, in the above explanation, an example was given in which a print head 24a with nozzles 24b arranged in a single row was used as the inkjet print head 24a. However, the explanation is not limited to this, and a print head with multiple rows of nozzles 24b may be used, or multiple print heads 24a may be arranged in a line along the transport direction A1.

[0067] Furthermore, although the above description provided an example of a first drying device 26 and a second drying device 36, the system is not limited to this, and either the first drying device 26 or the second drying device 36 may be provided, or neither the first drying device 26 nor the second drying device 36 may be provided.

[0068] Furthermore, while the above description illustrates a configuration in which the first printing device 20 and the second printing device 30 are stacked vertically and printed on both sides or one side of the tablet T, the configuration is not limited to this. Alternatively, only the first printing device 20 may be provided, and only one side of the tablet T may be printed.

[0069] Furthermore, in the above description, it was illustrated that the first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db are positioned to face the tablet T being transported on a horizontal plane. However, the explanation is not limited to this configuration, and they may also be positioned to face the tablet T being transported on a curved surface.

[0070] Furthermore, while the above explanation exemplified the case where the three-dimensional imaging camera C1 is located downstream of the laser beam irradiation unit L1 in the transport direction A1, it is not limited to this configuration and may be located upstream.

[0071] Furthermore, while the above description illustrates the detection of cracks, chips, and dirt on the tablet T by the first imaging device 23 and the third imaging device 33, the explanation is not limited to this. For example, cracks and chips on the tablet T may be detected by the first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db, while only dirt on the tablet T may be detected by the first imaging device 23 and the third imaging device 33.

[0072] Furthermore, while the above explanation exemplified generating a model image by rotating a single good product image E0 and combining multiple data points before and after rotation, the method is not limited to this. Alternatively, a model image may be generated by rotating multiple good product images individually and combining the resulting multiple data points.

[0073] Here, the single good product image E0 used for model image generation is obtained by imaging a good product tablet T using either or both of the first three-dimensional image acquisition device 3Da and the second three-dimensional image acquisition device 3Db. Individual differences exist in the tablets T, and their surfaces have fine irregularities (roughness). If the single good product image E0 is used as the model image as is, these individual differences will be included in the model image. This can cause false detections during inspection processing using the model image. By rotating the single good product image E0 and combining multiple data before and after rotation to generate the model image, it is possible to prevent such individual differences in the tablets T from being included in the model image, and to generate a model image with smooth edges as shown in Figure 9. Furthermore, by preparing good product images of multiple different tablets T and combining the data obtained by rotating them, it is possible to further prevent individual differences in the tablets T from being included in the good product image.

[0074] Furthermore, while the above description only mentioned that it is preferable to have the same suction force for each suction chamber 21f and 31f from the first detection device 22 to the second imaging device 25, similarly, it is preferable to have the same suction force for the second printing device 30 from the second detection device 32 to the fourth imaging device 35.

[0075] Here, the aforementioned tablet T can include tablets used for pharmaceutical, edible, cleaning, industrial, or fragrance purposes. Furthermore, tablet T can include uncoated tablets, sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multilayer tablets, and core tablets, and various types of capsule tablets such as hard capsules and soft capsules can also be included in tablet T. In addition, tablet T can take various shapes such as disc-shaped, lens-shaped, triangular, and oval. Moreover, if the tablet T to be printed is for pharmaceutical or edible purposes, edible ink is preferable as the ink used. This edible ink may be synthetic dye ink, natural dye ink, dye ink, or pigment ink.

[0076] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0077] 1. Tablet printing machine 3D1 Three-dimensional image acquisition unit 3Da First Three-Dimensional Image Acquisition Device 3Db Second Three-Dimensional Image Acquisition Device 10 Feeding device 11 Hoppa 12 Alignment Feeders 13 Transfer Feeder 20 First Printing Apparatus 21. First conveying device 21a Conveyor belt 21b Drive pulley 21c Driven pulley 21d motor 21e Position detector 21f Suction Chamber 21g suction hole 22 First detection device 22a Detection unit 23 First imaging device 23a Imaging unit 24 First print head unit 24a print head 24b Nozzle 25 Second imaging device 25a Imaging section 26. First drying apparatus 30 Second printing device 31. Second conveying device 31a Conveyor belt 31b Drive pulley 31c Driven pulley 31d motor 31e Position detector 31f Suction Chamber 32 Second detection device 33 Third Imaging Device 34. Second print head unit 35. Fourth imaging device 36. Second drying apparatus 40 Recovery device 50 Control device 51 Image Processing Unit 52 Printing Processing Unit 53 Inspection Processing Unit 54 Memory section C1 Three-Dimensional Imaging Camera E. Composite image Ec composite image E0 Good condition image L1 Laser beam irradiation area P transport path T Tablets

Claims

1. An acquisition unit that acquires a three-dimensional image having height information for each point of the tablet, A memory unit that stores model images, A determination unit compares the three-dimensional image acquired by the acquisition unit with the model image stored by the storage unit, and determines defects in the tablet based on the comparison result between the three-dimensional image and the model image. Equipped with, The shape of the aforementioned tablet is a shape that has rotational symmetry. The aforementioned model image is generated by rotating multiple good product images, each containing height information for each good product tablet, multiple times to generate multiple good product images, and then combining these multiple good product images. Tablet inspection device.

2. The system further includes a generation unit that generates multiple good product images by rotating the good product image multiple times, and generates the model image by combining the multiple good product images. The tablet inspection device according to claim 1.

3. The aforementioned good product image includes point cloud data which is the height information for each point, The generation unit rotates the point cloud data included in the good product image with the center of the tablet as the rotation center. The coordinate position of the rotation center does not coincide with the coordinate position of the point that constitutes the point cloud data. The tablet inspection device according to claim 2.

4. The generation unit generates multiple images of good products by rotating the good product image multiple times at a predetermined angle, and then synthesizes the multiple images of good products. The predetermined angle is an angle such that the sum of the angles obtained by rotating the good product image does not equal 360 degrees. The tablet inspection device according to claim 2.

5. The generation unit generates multiple images of good products by rotating the good product image at multiple different angles, and then synthesizes the multiple images of good products. The tablet inspection device according to claim 2.

6. The device further comprises a conveying device for transporting the aforementioned tablets, The acquisition unit has an imaging unit that images the tablets being transported by the transport device. A tablet inspection device according to any one of claims 1 to 5.

7. A conveying device for transporting tablets, A tablet inspection device for inspecting the tablets transported by the transport device, A printing device that prints on the tablets being transported by the transport device, Equipped with, The aforementioned tablet inspection device, An acquisition unit that acquires a three-dimensional image having height information for each point of the aforementioned tablet, A memory unit that stores model images, A determination unit compares the three-dimensional image acquired by the acquisition unit with the model image stored by the storage unit, and determines defects in the tablet based on the comparison result between the three-dimensional image and the model image. Equipped with, The shape of the aforementioned tablet is a shape that has rotational symmetry. The aforementioned model image is generated by rotating multiple good product images, each containing height information for each good product tablet, multiple times to generate multiple good product images, and then combining these multiple good product images. Tablet printing machine.

Images