JP2019124520A - Tablet inspection method and tablet inspection device - Google Patents

Abstract

To provide a tablet inspection method for detecting a chip in a tablet occurring at a boundary between a principal face and a side face in captured images where the principal face and a side face of a tablet are in contact with each other.SOLUTION: The tablet inspection method comprises steps (a) to (c). In the step (a), a tablet is imaged and captured images are generated in which both of a first principal face and a side face of the tablet are imaged. In the step (b), a boundary edge corresponding to a boundary between a principal face region and a side face region occupied by each of the principal face and the side face of the tablet in the captured images is specified, and a first approximate line approximating the boundary edge is calculated on the basis of a function that indicates the shape of the boundary in the captured images. In the step (c), it is determined that there is occurrence of a chip on a circumferential edge of the tablet when the distance between each pixel on the boundary edge and the first approximate line is longer than a prescribed threshold.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a tablet inspection method and a tablet inspection apparatus, and more particularly to an inspection technique using a camera for imaging a tablet.

  BACKGROUND Conventionally, tablet inspection apparatuses for inspecting the appearance of tablets have been proposed (for example, Patent Documents 1 to 3). In Patent Document 1, the inspection unit includes transport means for transporting the tablets, and four imaging devices (cameras) for imaging the tablets being transported. The two cameras image the top and bottom of the tablet respectively, and the remaining two cameras image the sides of the tablet from opposite sides. The inspection unit performs an appearance inspection by performing image processing on each of the captured images captured by the camera.

  In this patent document 1, since a plurality of cameras are used, the cost is high. On the other hand, in patent document 2, the inspection apparatus is provided with the conveyor which conveys a tablet, and one imaging device for imaging the tablet in conveyance. The imaging device captures an image so that the upper surface of the tablet viewed from the upper side and the side surface of the tablet viewed from four sides are included in one captured image.

  Specifically, the imaging device includes one camera and four prisms. The camera is disposed on the upper side of the tablet, and light from the upper surface of the tablet is imaged on the imaging surface of the camera. Also, the prisms are arranged in the four sides of the tablet and reflect light from the side of the tablet to the camera. The light is also imaged on the imaging surface of the camera. Thereby, the camera can image the external appearance of the tablet seen from five directions. The inspection apparatus performs an appearance inspection of a tablet by performing image processing on a captured image captured by a camera.

  Moreover, also in Patent Document 3, the inspection apparatus includes a transport unit that transports the tablet, and an imaging device that captures an image of the tablet during transport. More specifically, the imaging device has a camera and two prisms. The camera is disposed on the upper side of the tablet, and light from the upper surface of the tablet is imaged on the imaging surface of the camera. The two prisms are respectively disposed at positions sandwiching the tablet, and reflect light from the side of the tablet to the camera. The light is also imaged on the imaging surface. The prisms are arranged so that the camera can image the side of the tablet from the side. The inspection apparatus performs an appearance inspection of a tablet by performing image processing on a captured image captured by a camera.

WO 2015/041112 JP, 2012-123009, A JP 2004-45097 A

  For example, if the upper surface of the tablet is imaged vertically as in Patent Documents 1 to 3, the chipping generated on the periphery of the upper surface of the tablet is located on the outer periphery of the tablet. In addition, the outer periphery of the tablet here means the outline of the tablet area which a tablet occupies in a captured image. Thus, the chippings located on the outer periphery of the tablet can be easily detected from the captured image. This is because the chipping occurs at the boundary between the tablet area and the background area in the captured image.

  On the other hand, if, for example, the tablet is imaged obliquely from above, this one-way imaging captures both the top and side surfaces of the tablet. In this case, the top and side surfaces of the tablet are in contact with each other in the captured image. That is, in this captured image, a portion in contact with the side surface of the periphery of the top surface of the tablet is located not inside the periphery of the tablet (outline of the tablet region) but inside the tablet region. When a chipping of the tablet occurs in the portion, it is difficult to detect the chipping from the captured image.

  Then, this invention aims at the tablet inspection method and tablet inspection apparatus which can detect the chipping of the tablet which arose on the boundary of the main surface and the side in the image pick-up picture which the main surface and the side of a tablet contact mutually. .

  A first aspect of the tablet inspection method is a tablet inspection method for inspecting the appearance of a tablet having a pair of first main surfaces and a second main surface and a side surface, and imaging a tablet to obtain the first main surface And a step (a) of generating a captured image in which both of the side surfaces are captured, and corresponding to a boundary between a main surface region and a side surface region occupied by the first main surface and the side surface of the tablet in the captured image. A boundary edge is identified, and a first approximate line approximating the boundary edge is calculated based on a function indicating the shape of the boundary in the captured image, and each pixel on the boundary edge and the step And (c) determining that a chipping has occurred in the peripheral edge of the first main surface of the tablet when the distance between the first approximate line and the first approximate line is longer than a predetermined threshold.

  A second aspect of the tablet inspection method is the tablet inspection method according to the first aspect, wherein the main surface area and the side surface area constitute a tablet area occupied by the tablet in the captured image, The step (b) is a step (b1) of performing edge detection processing on the captured image to generate an edge image, and a step (b2) of identifying a tablet edge corresponding to the contour of the tablet area from the edge image And a portion of the periphery of the first main surface in the captured image that is a part of the contour of the tablet region, and a main surface outer edge and a side surface respectively corresponding to the periphery of the second main surface in the captured image Extracting an outer edge from the tablet edge (b3); searching for a pixel in a search area at a predetermined distance from the side outer edge along the predetermined direction in the edge image The step of specifying the boundary edge (b4) and the function of indicating the shape of the outline of the main surface area in the captured image, the first of the main surface outer edge and the pair of main surface edges that are the boundary edge And (2) calculating a second approximation line (b5) and extracting the first approximation line of the boundary edge from the second approximation line (b6).

  A third aspect of the tablet inspection method is the tablet inspection method according to the second aspect, wherein the tablet has a substantially disc shape, the function is a function indicating an ellipse, and the second approximate line Is an ellipse.

  A fourth aspect of the tablet inspection method is the tablet inspection method according to the second or third aspect, wherein, in the step (b4), a pixel in the search area of the edge image and the pixel is The boundary edge is identified by searching for a pixel whose pixel value of the corresponding captured image pixel is larger than a predetermined threshold value.

  A fifth aspect of the tablet inspection method is the tablet inspection method according to the third or fourth aspect, wherein, in the step (b4), in the search area, from the side outer edge toward the main surface outer edge in the search area The pixel is searched to identify the boundary edge.

  A sixth aspect of the tablet inspection method is the tablet inspection method according to any one of the second to fifth aspects, wherein from the second approximate line of the main surface edge calculated in the step (b5), Extracting the third approximate line of the main surface outer edge, and when the distance between each pixel on the main surface outer edge and the third approximate line is longer than a predetermined threshold value, Determining the chipping at the periphery of the first main surface.

  A seventh aspect of the tablet inspection method is the tablet inspection method according to any one of the second to sixth aspects, wherein from the second approximate line of the main surface edge calculated in the step (b5), The step of extracting a fourth approximate line of the side outer edge, and when the distance between each pixel on the side outer edge and the fourth approximate line is longer than a predetermined threshold, the second step of the tablet And J. determining the chipping of the peripheral edge of the main surface.

  An eighth aspect of the tablet inspection apparatus is a tablet inspection apparatus for inspecting the appearance of a tablet having a pair of first main surfaces and a second main surface and a side surface, comprising imaging a tablet and processing the first main surface And an imaging unit that generates a captured image including both of the side surfaces, and an image processing unit, wherein the image processing unit is a main surface area occupied by the first main surface and the side surface of the tablet in the captured image. A boundary edge corresponding to the boundary between the image and the side area is identified, and a first approximate line approximating the boundary edge is calculated based on a function indicating the shape of the boundary in the captured image; When the distance between each upper pixel and the first approximate line is longer than a predetermined threshold value, it is determined that the periphery of the first main surface of the tablet is chipped.

  According to the first aspect of the tablet inspection method and the eighth aspect of the tablet inspection apparatus, in the imaged image in which the first main surface and the side surface of the tablet are in contact with each other, the tablet produced on the boundary of the first main surface and the side surface Chipping can be detected.

  According to the second aspect of the tablet inspection method, the first approximate line of the boundary edge can be appropriately obtained.

  According to the third aspect of the tablet inspection method, since a suitable function is adopted according to the shape of the tablet, it is possible to calculate the second approximate line closer to the main surface of the tablet.

  According to the fourth aspect of the tablet inspection method, it is possible to calculate a first approximate line closer to the shape of the boundary between the main surface and the side surface in the captured image.

  According to the fifth aspect of the tablet inspection method, even if a dividing line is formed on the main surface of the tablet, it is possible to avoid false detection of an edge corresponding to the dividing line as a boundary edge.

  According to the sixth aspect of the tablet inspection method, chipping of a tablet generated on the periphery of the first main surface can be detected.

  According to the seventh aspect of the tablet inspection method, chipping of a tablet generated on the periphery of the second main surface can be detected.

It is a figure showing roughly an example of composition of a tablet inspection device. It is a perspective view which shows an example of a tablet. It is a figure showing roughly an example of an internal configuration of an imaging head. It is a figure showing roughly an example of an internal configuration of an imaging head. It is a figure showing roughly an example of an image pick-up picture. It is a figure showing roughly an example of an image pick-up picture. It is a flow chart which shows an example of operation of a tablet inspection device. It is a figure which shows roughly an example of the tablet edge corresponding to the outer periphery of a tablet in a captured image. It is a figure for demonstrating an example of the identification method of the boundary edge corresponding to the boundary between the main surface and side surface of a tablet in a captured image. It is a flowchart which shows an example of the identification method of a boundary edge. It is a figure which shows roughly an example of various edges and its approximation line. It is a flow chart which shows an example of inspection processing. It is a flow chart which shows a more concrete example of inspection processing. It is a flowchart which shows another more specific example of a test | inspection process. It is a flowchart which shows another example of the identification method of a boundary edge. It is a figure for demonstrating another example of the identification method of a boundary edge. It is a figure which shows roughly another example of various edges and its approximation line. It is a figure which shows roughly another example of various edges and its approximation line.

  Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, for the purpose of easy understanding, the dimensions and the numbers of the respective parts are drawn in an exaggerated or simplified manner as necessary. In the drawings, parts having similar configurations and functions are denoted by the same reference numerals, and redundant description will be omitted in the following description. Further, in each drawing, in order to clarify the directional relationship of the components, an XYZ orthogonal coordinate system in which the Z-axis direction is a vertical direction and the XY plane is a horizontal plane is appropriately attached.

  FIG. 1 is a view schematically showing an example of the configuration of a tablet printing apparatus 10. As shown in FIG. The tablet printing apparatus 10 includes a tablet inspection apparatus 1 and a print head 6.

  The tablet inspection apparatus 1 is an apparatus for inspecting the appearance of the tablet 9. FIG. 2 is a perspective view schematically showing an example of the tablet 9. In the example of FIG. 2, the tablet 9 has a substantially disc shape. Specifically, the tablet 9 includes a pair of main surfaces 9a and 9b and a side surface 9c. The main surfaces 9a and 9b have substantially the same circular shape in plan view. One and the other of the main surfaces 9a and 9b may be referred to as front and back, respectively, and may also be referred to as top and bottom.

  The main surface 9a and the side surface 9c of the tablet 9 are connected to each other to form a corner, and the main surface 9b and the side surface 9c are also connected to each other to form a corner. The diameter of the tablet 9 may be set to, for example, about 5 mm to about 10 numbers, and the thickness thereof may be set to, for example, about 5 mm or less.

  As exemplified in FIG. 2, a dividing line 91 may be formed on the major surface 9 a of the tablet 9. The dividing line 91 is a groove extending straight through the center of the main surface 9a from end to end of the main surface 9a. The same dividing line may be formed on the main surface 9b.

  Referring to FIG. 1, tablet inspection apparatus 1 includes hopper 2, transport drum 3, transport unit 4, imaging head 5, sorting unit 7 and control unit 8.

  The hopper 2 is a loading unit for loading the tablet 9 into the tablet printing apparatus 10. The hopper 2 is provided above the ceiling of a housing (not shown) of the tablet printing apparatus 10. The tablets 9 fed from the hopper 2 are guided to the transport drum 3. The elements other than the hopper 2 are provided inside the housing of the tablet printing apparatus 10.

  The transport drum 3 has a substantially cylindrical shape, and the central axis of the transport drum 3 is disposed along the Y-axis direction. The transport drum 3 is rotated counterclockwise on the paper surface of FIG. The rotation drive motor is controlled by, for example, the control unit 8.

  A plurality of suction holes (not shown) are formed along the circumferential direction on the outer peripheral surface of the transport drum 3. Each of the plurality of suction holes is in communication with a suction mechanism (not shown) provided inside the conveyance drum 3. The suction mechanism is controlled by, for example, the control unit 8. By operating the suction mechanism, negative pressure lower than atmospheric pressure can be applied to each of the plurality of adsorption holes. Thus, each suction hole of the transport drum 3 can hold one tablet 9 by suction.

  The transport unit 4 is disposed below the transport drum 3. The tablets 9 adsorbed and held on the outer peripheral surface of the transport drum 3 move in the circumferential direction as the transport drum 3 rotates. When the tablet 9 moves to the lower side of the transport drum 3, the suction mechanism releases the adsorption on the tablet 9, whereby the tablet 9 falls and is delivered to the transport unit 4.

  The transport unit 4 transports the tablets 9. In the example of FIG. 1, the transport unit 4 is a belt conveyor, and includes a transport belt 41 and a pair of pulleys 42. The pair of pulleys 42 is disposed, for example, at an interval in the X-axis direction, and the central axis of itself is disposed along the Y-axis direction. Each of the pair of pulleys 42 rotates around its own central axis.

  The transport belt 41 is stretched around a pair of pulleys 42. As at least one of the pair of pulleys 42 is rotationally driven by a drive motor (not shown), the transport belt 41 travels in the direction shown by the arrow in FIG. 1. The drive motor is controlled by, for example, the control unit 8.

  Also on the outer peripheral surface of the conveyance belt 41, a plurality of suction holes (not shown) are formed along the circumferential direction. Each of the plurality of suction holes is in communication with a suction mechanism (not shown) provided inside the conveyance belt 41. The suction mechanism is controlled by, for example, the control unit 8. By operating the suction mechanism, negative pressure lower than atmospheric pressure can be applied to each of the plurality of adsorption holes. Thus, each suction hole of the conveyance belt 41 can hold one tablet 9 by suction.

  As the transport belt 41 travels while suction-holding the tablets 9, the tablets 9 are transported in the direction away from the transport drum 3 along the X-axis direction.

  The imaging head 5 is disposed on the downstream side of the transport drum 3 midway along the transport path of the tablets 9 by the transport portion 4 and at a position facing the transport portion 4. The imaging area of the imaging head 5 includes a part of the transport belt 41. When the tablet 9 moves in the imaging area, the imaging head 5 images the tablet 9 to generate a captured image. The imaging head 5 outputs this captured image to the control unit 8. An example of a specific internal configuration of the imaging head 5 will be described in detail later.

  The control unit 8 inspects the appearance of the tablet 9 by performing image processing on the input captured image. The controller 8 determines that the tablet 9 is defective if the appearance of the tablet 9 is defective, and determines that the tablet 9 is good if the appearance of the tablet 9 is not defective. Examples of the defects include impurities attached to the tablet 9 or defects such as defects in shape (e.g., chipping) of the tablet 9. An example of specific image processing by the control unit 8 will be described in detail later.

  The print head 6 is disposed on the downstream side of the imaging head 5 above the transport belt 41 while the tablets 9 are being transported. The print head 6 is controlled by, for example, the control unit 8 and performs a printing process on the tablet 9. The print head 6 includes a plurality of discharge nozzles (not shown), and discharges ink droplets from the discharge nozzles by an inkjet method. The inkjet method may be a piezo method in which a piezoelectric element (piezoelectric element) is deformed by applying a voltage to discharge ink droplets, or a heater is energized to heat the ink, whereby the ink droplets are discharged. It may be a thermal method of discharging the ink. In the present embodiment, in order to print the tablets 9, as the ink, an edible ink manufactured using a material recognized by the Food Sanitation Law is used.

  In the example of FIG. 1, since the print head 6 is located on the downstream side of the transport path from the imaging head 5, the control unit 8 may determine the necessity of the printing process according to the inspection result of the tablet 9. . More specifically, when it is determined that the tablet 9 is non-defective in the appearance inspection, the control unit 8 controls the print head 6 to print the tablet 9 and determines that the tablet 9 is defective. In such a case, the print head 6 may be controlled so as not to print the tablet 9. According to this, unnecessary print processing can be avoided.

  The sorting unit 7 sorts the tablets 9 in accordance with the result of the appearance inspection. For example, the sorting unit 7 has a non-defective box and a defective item box. These boxes have a box-like shape opened upward. The non-defective box stores the tablets 9 determined to be non-defective, and the defective box stores the tablets 9 determined to be non-defective. For example, these boxes are arranged side by side along the X-axis direction on the lower side of the transport belt 41. When the tablet 9 judged to be non-defective is positioned immediately above the opening of the non-defective box, the control unit 8 controls the suction mechanism in the transport belt 41 to release the adsorption on the tablet 9. Thereby, the tablet 9 falls into the inside of the non-defective item box and is accommodated therein. The tablets 9 determined to be defective are similarly stored inside the defective box.

  As described above, the control unit 8 controls various components, and performs an appearance inspection of the tablet 9 by performing image processing on a captured image input from the imaging head 5.

  The control unit 8 is an electronic circuit device, and may have, for example, a data processing device and a storage medium. The data processing device may be, for example, an arithmetic processing device such as a CPU (Central Processor Unit). The storage unit may have a non-transitory storage medium (for example, a ROM (Read Only Memory) or a hard disk) and a temporary storage medium (for example, a RAM (Random Access Memory)). The non-temporary storage medium may store, for example, a program that defines a process performed by the control unit 8. The processing unit executes this program, whereby the control unit 8 can execute the processing defined in the program. Of course, part or all of the processing performed by the control unit 8 may be performed by hardware.

<Imaging head>
The imaging head 5 images the tablet 9 on the way of conveyance from the direction in which at least two surfaces of the tablet 9 appear. The tablets 9 may be adsorbed and held by the transport belt 41 with the main surface 9b facing the transport belt 41, and may be adsorbed and held by the transport belt 41 with the main surface 9a facing the transport belt 41. It is also possible. In the following, for convenience of explanation, it is assumed that the tablet 9 is held on the transport belt 41 with the main surface 9 b facing the transport belt 41 side. Further, in the state where the tablets 9 are adsorbed and held by the conveyance belt 41, at least a part of the side surface 9 c on the main surface 9 a side is exposed from the conveyance belt 41.

  The imaging head 5 images the tablet 9 from the direction in which both the main surface 9 a and the side surface 9 c of the tablet 9 are captured. Thereby, a captured image in which both the main surface 9 a and the side surface 9 c of the tablet 9 are captured is generated. FIG. 3 and FIG. 4 are diagrams schematically showing an example of the internal configuration of the imaging head 5. For example, the imaging head 5 includes an inspection camera 51, a lens group 52, a mirror 53, and a pyramidal mirror 54. The inspection camera 51 is an image sensor such as, for example, a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor. The inspection camera 51 is disposed in a position in which the imaging surface thereof faces the conveyance belt 41 at a position where it faces a part of the conveyance path of the tablet 9 in the Z-axis direction.

  The mirror 53 is provided to guide light from the major surface 9 a and the side surface 9 c of the tablet 9 to the pyramidal mirror 54 described later. In describing the position of the mirror 53, for convenience, it is assumed that the tablet 9 is stopped at a position facing the inspection camera 51 in the Z-axis direction. Referring to FIG. 3, mirror 53 is located between inspection camera 51 and tablet 9 in the Z-axis direction, and is disposed outside of tablet 9 in plan view (that is, viewed along the Z-axis direction). It is done. Also, the mirror 53 is disposed to face each surface of the pyramidal mirror 54.

  The pyramidal mirror 54 guides the light from the major surface 9 a and the side surface 9 c of the tablet 9 reflected by the mirror 53 to the imaging surface of the inspection camera 51 via the lens group 52. The pyramidal mirror 54 is configured of four mirrors, and the pyramidal mirror 54 is disposed to face each of the mirrors 53.

  A part of the light reflected or scattered by the main surface 9a and the side surface 9c of the tablet 9 proceeds obliquely upward to one of the mirrors 53, is reflected by the mirror 53, and the light reflected by the mirror 53 is pyramidal type After being reflected by the mirror 54, an image is formed on the imaging surface of the inspection camera 51 through the lens group 52. In other words, the angles of the reflecting surfaces of the mirror 53 and the pyramidal mirror 54 with respect to the ground are adjusted so that light traveling obliquely upward from the major surface 9 a and the side surface 9 c of the tablet 9 can be reflected toward the imaging surface of the inspection camera 51 It is done.

  Thereby, the inspection camera 51 can image the appearance of the tablet 9 viewed from the mirror 53. That is, the inspection camera 51 can substantially image the tablet 9 in an oblique direction, and the captured image includes both the main surface 9 a and the side surface 9 c of the tablet 9. In FIG. 3, an example of the light path is shown by a broken line.

  In the example of FIG. 4, a plurality of (four in the drawing) mirrors 53 are arranged. For example, two mirrors 53 are spaced apart in the X-axis direction, and the remaining two mirrors 53 are spaced apart in the Y-axis direction. According to this, the tablet 9 is surrounded by the mirror 53 in four directions in plan view. Further, pyramidal mirrors 54 are disposed at the centers of the mirrors 53 at intervals. The light reflected by each mirror 53 is further reflected by the pyramidal mirror 54, and is imaged on the imaging surface of the inspection camera 51 through the lens group 52. Specifically, the light reflected by the four mirrors 53 is imaged on different areas of the imaging surface of the inspection camera 51. Thereby, the imaging head 5 images the tablet 9 from four directions, and generates a captured image including the appearance of the tablet 9 viewed from four directions.

  FIG. 5 is a diagram schematically illustrating an example of the captured image IM1. The captured image IM1 includes the appearance of the tablet 9 viewed from four directions, and in any of these, the main surface 9a and the side surface 9c of the tablet 9 are shown. Here, since the tablet 9 is imaged from four directions, the side surface 9c of the tablet 9 can be imaged over the entire circumference. Hereinafter, the main surface 9a and the side surface 9c of the tablet 9 shown in the captured image IM1 will be referred to as the main surface 9aa and the side surface 9ca, respectively, in order to be distinguished from the main surface 9a and the side surface 9c of the actual tablet 9.

  The imaging head 5 may have an illumination light source (not shown). The illumination light source irradiates the tablet 9 with light. Thereby, the brightness of the tablet 9 in the captured image IM1 can be improved.

  In the examples of FIGS. 3 and 4, although the light path is bent by the mirror 53 and the pyramidal mirror 54, this is not necessarily the case. Another optical element such as a prism may be employed as an element for bending the light path.

<Inspection>
The control unit 8 performs image processing on the captured image IM1 input from the imaging head 5, and performs an appearance inspection of the captured tablet 9. Thus, the control unit 8 functions as an image processing unit.

  In the following, in order to simplify the description, the appearance of the tablet 9 viewed from one direction will be described. FIG. 6 is a view schematically showing an example of a captured image IM11 obtained by imaging the tablet 9 having a defect from one direction. In the example of FIG. 6, a chipping B1 is present at the boundary between the major surface 9aa and the side surface 9ca of the tablet 9.

  The control unit 8 performs image processing on the captured image IM11 to detect the chipping B1 of the tablet 9. The following more specifically describes.

  FIG. 7 is a flowchart showing an example of the operation in the tablet inspection apparatus 1. First, in step S1, the imaging head 5 captures an image of the tablet 9 during conveyance from the direction in which both the main surface 9a and the side surface 9c of the tablet 9 appear, and a captured image in which both the main surface 9a and the side surface 9c of the tablet 9 appear Generate IM11. The imaging head 5 outputs the captured image IM11 to the control unit 8.

  Next, the control unit 8 detects a main surface edge corresponding to the contour of the main surface area Ra occupied by the main surface 9aa of the tablet 9 in the captured image IM11. As shown in FIG. 6, in the case where chipping B1 occurs at the boundary between main surface region Ra and side surface region Rc, the main surface edge is an edge corresponding to the outline of main surface 9aa including chipping B1. Understand that there is. The detection of the main surface edge is performed, for example, by a series of processes of steps S2 to S5 in FIG.

  First, in step S2, the control unit 8 performs edge detection processing on the captured image IM11 to generate an edge image. However, here, the control unit 8 performs edge detection processing on the captured image IM11 from which the background area BR has been deleted. The background region BR is a region other than the tablet region TR occupied by the tablet 9 in the captured image IM11. The tablet region TR is constituted by the main surface region Ra and the side surface region Rc.

  In order to delete the background area BR, the control unit 8 first distinguishes between the tablet area TR and the background area BR in the captured image IM11. For example, the control unit 8 uses a binarization process on the captured image IM11 to distinguish the tablet area TR from the background area BR. Since the background area BR includes the conveyance belt 41, if the contrast between the actual color of the conveyance belt 41 and the color of the tablets 9 is increased in order to accurately distinguish the tablet area TR and the background area BR. Good. For example, when the tablets 9 are white-based, the transport belt 41 is made black. When the control unit 8 specifies the background area BR, the control unit 8 deletes the background area BR in the captured image IM11. For example, the control unit 8 deletes the background area BR by setting the pixel values of all the pixels in the background area BR to zero.

  Next, the control unit 8 performs edge detection processing on the captured image IM11 from which the background area BR has been deleted, and generates an edge image. Although the specific processing method of the edge detection processing need not be particularly limited, an example thereof will be briefly described. For example, the control unit 8 performs edge strength processing on the pickup image IM11 after removal to generate an edge strength image. The edge strength processing includes, for example, calculation processing of the difference in pixel value between the respective pixels, whereby an area with a large difference in pixel value between the pixels in the captured image IM11 becomes an edge strength image. In the edge strength image, the control unit 8 determines for each pixel whether the pixel value is larger than a predetermined edge threshold. The edge threshold may be set in advance and stored in the storage medium of the control unit 8, for example. The control unit 8 detects a pixel having a pixel value larger than the edge threshold to generate an edge image.

  Since this edge image is generated based on the captured image IM11 from which the background area BR has been removed, an edge in the background area BR (for example, unevenness of the transport belt 41) is not detected in the edge image. That is, the edge (hereinafter referred to as a tablet edge) corresponding to the contour of the tablet region TR is positioned at the outermost periphery of the edge group in the edge image.

  Therefore, in step S3, the control unit 8 specifies the tablet edge as follows. That is, the control unit 8 specifies the edge located at the outermost periphery among the edge group in the edge image as the tablet edge P0 (see FIG. 8).

  FIG. 8 is a view schematically showing an example of the tablet edge P0. In the example of FIG. 8, the tablet edge P0 is schematically shown divided into a plurality of edges. The tablet edge P0 is composed of a side outer edge P1, a main surface outer edge P2, and a pair of side ridge line edges P4. The side outer edge P1 is an edge corresponding to a portion of the periphery of the main surface 9b of the tablet 9 that is captured in the captured image IM11. Since the major surface 9b has a circular shape, the side outer edge P1 ideally has a semi-elliptical shape. The term "semi-elliptical shape" as used herein refers to a shape obtained by dividing an ellipse into two at its major axis.

  The main surface outer edge P2 is an edge corresponding to a portion of the periphery of the main surface 9aa of the tablet 9 in the captured image IM11 which is not in contact with the side surface 9ca. It can be said that this main surface outer edge P2 is an edge corresponding to a part of the contour of the tablet region TR in the periphery of the main surface 9aa of the tablet 9. Since the major surface 9a has a circular shape, the major surface outer edge P2 ideally has a semi-elliptical shape. More specifically, the side outer edge P1 and the main surface outer edge P2 have a semi-elliptical shape that bulges to the opposite side.

  The pair of side edge line edges P4 ideally extends in a straight line, and connects both ends of the main surface outer edge P2 to both ends of the side surface outer edge P1. The pair of side edge line edges P4 is an edge corresponding to a part of the outline of the side surface 9ca of the tablet 9 in the captured image IM11. The pair of side edge line edges P4 extend substantially in parallel, and the extending direction thereof is predetermined by the arrangement of the internal configuration of the imaging head 5. Here, it is assumed that the side edge line edge P4 extends in a direction intersecting at approximately 45 degrees with respect to the lateral direction in the captured image IM11.

  In addition, a pair of side ridgeline edge P4 is not completely perfect parallel in fact. The pair of side edge line edges P4 are slightly inclined so as to be closer to each other as the side outer edge P1 side is approached. In the following, for the sake of simplicity, it is assumed that the pair of side ridge edges P4 are parallel. If it thinks more strictly, what is necessary is just to grasp the extending direction of side edge line edge P4 described below as the direction represented by the bisector of the extending direction of a pair of side edge line edge P4.

  Referring again to FIG. 7, in step S4, control unit 8 extracts side outer edge P1 and main surface outer edge P2 from tablet edge P0 identified in step S3. For example, the control unit 8 identifies an edge of the tablet edge P0 that extends along the predetermined direction D1 (= the extension direction of the side edge P4) as the side edge P4. Then, the control unit 8 identifies one of the two edges obtained by removing the side edge line edge P4 from the tablet edge P0 on the predetermined side (upper right side in the figure) as the side outer edge P1, and the other as the main surface outer edge P2. Identify

  Next, in step S5, the control unit 8 specifies the boundary edge P3 from the edge image. The boundary edge P3 is an edge corresponding to the boundary between the major surface 9aa and the side surface 9ca of the tablet 9 in the captured image IM11. In other words, the boundary edge P3 is an edge corresponding to the boundary between the main surface area Ra and the side surface area Rc. Further, as shown in FIG. 6, when the notch B1 is present, the boundary edge P3 includes a part of the edge corresponding to the outline of the notch B1. A specific example of the boundary edge P3 will be described later.

  In the case where no chipping B1 occurs in the tablet 9, the boundary edge P3 ideally has a semi-elliptical shape that bulges on the opposite side to the major surface outer edge P2. That is, the boundary edge P3 has the same shape as the side surface outer edge P1. Furthermore, since the tablet 9 is not so thick here, it can be considered that the boundary edge P3 and the side outer edge P1 have substantially the same shape, unless the tablet 9 has a chipping B1. That is, the boundary edge P3 exists in a region in which the side surface outer edge P1 is moved in parallel along the predetermined direction D1 toward the main surface outer edge P2 by the length of the side surface ridge line edge P4. Since the length of the side ridge line edge P4 is predetermined according to the thickness of the tablet 9 and the arrangement of the internal configuration of the imaging head 5, if the side outer edge P1 is specified, the region where the boundary edge P3 exists is estimated. be able to.

  Therefore, the control unit 8 searches for a boundary edge P3 by searching for pixels in a search area R1 (see also FIG. 9) separated from the side surface outer edge P1 by a predetermined distance toward the main surface outer edge P2 along the predetermined direction D1. Identify. FIG. 9 is a view schematically showing an example of the search area R1. In explaining an example of the search area R1, a center line L0 of the search area R1 and lines L1 to L4 forming an outline of the search area R1 are introduced.

  The center line L0 is a line obtained by moving the side outer edge P1 by the length of the side edge P4 along the predetermined direction D1 toward the main surface outer edge P2. Further, although in the example of FIG. 9 a part of the boundary edge P3 and a part of the center line L0 are shown to coincide with each other, they may actually be different from each other.

  The lines L1 and L2 are lines obtained by moving the center line L0 along the predetermined direction D1 to the opposite side by a predetermined width. This predetermined width is preset according to the size of the chipped chip B1 assumed. In FIG. 9, the line L1 is closer to the side outer edge P1 than the line L2. The lines L3 and L4 extend along the predetermined direction D1 and connect both ends of the lines L1 and L2, respectively. The search area R1 is an area surrounded by one set of these lines L1 to L4.

  In FIG. 9, a chipped edge P ′ corresponding to the contour of the chip B1 and a part of the dividing line edge P5 corresponding to the dividing line 91 are also shown. In the following, for convenience of explanation, a pixel group arranged in the search area R1 along the predetermined direction D1 will be referred to as a "row".

  FIG. 10 is a flowchart illustrating an example of the search process of the control unit 8. First, in step S51, the control unit 8 initializes the values N and M to one. The value N indicates the number of the row in the search area R1, and the value M indicates the number of the pixel belonging to the row. The first pixel is a pixel on the line L1, and the Mth pixel is a pixel next to the (M-1) th pixel in each row.

  Next, in step S52, the control unit 8 determines whether or not the Nth row and Mth pixel in the search area R1 of the edge image indicates an edge. If a negative determination is made, in step S53, the control unit 8 adds 1 to the value M to update the value M, and executes step S52 again using the updated value M. That is, if a pixel indicating an edge (hereinafter also referred to as an edge pixel) can not be detected, the same determination is made for the next pixel.

  When an affirmative determination is made in step S52, in step S54, the control unit 8 recognizes the pixel as a component of the boundary edge P3. Next, in step S55, the control unit 8 adds 1 to the value N to update the value N, and initializes the value M to 1. Next, at step S56, control unit 8 determines whether value N is larger than reference value Nref. The reference value Nref is the total number of rows included in the search area R1. That is, the control unit 8 determines whether all the rows have been searched. If it is determined that all the lines have not been searched, the control unit 8 executes step S52 again. If it is determined that all the lines have been searched, the control unit 8 ends the search processing.

  As described above, in each row in the search area R1, the control unit 8 sequentially selects pixels from the line L1 and specifies the edge pixel detected first as a component of the boundary edge P3. In the example of FIG. 9, the search direction of the pixel is schematically indicated by a solid arrow in the search area R1, and the end point of the arrow indicates a component of the boundary edge P3. According to this search processing, the pixel on the missing edge P 'is specified as a component of the boundary edge P3 as follows. That is, a pixel on the edge Pc 'on the line L1 side (that is, the side surface outer edge P1 side) of the chipped edge P' is identified as a component of the boundary edge P3. In FIG. 9, some of the pixels identified as components of the boundary edge P3 are schematically indicated by black circles.

  Further, according to the above-described search processing, the pixel on the dividing line edge P5 is not identified as a component of the boundary edge P3. Because the dividing line edge P5 is located on the main surface outer edge P2 side with respect to the boundary edge P3, the control unit 8 moves the search area R1 from the line L1 side to the line L2 side (that is, from the side surface outer edge P1 to the main surface This is because the search is made to the outer edge P2 side). That is, according to this search processing, the control unit 8 can specify the component of the boundary edge P3 before searching for the pixel of the dividing line edge P5.

  The control unit 8 specifies, as the main surface edge P23, a pair of the main surface outer edge P2 specified in step S4 and the boundary edge P3 specified in step S5. When the chipping B1 occurs, the major surface edge P23 does not have an ideal oval shape, and deviates from the ideal oval shape in a portion corresponding to the chip B1 (see also FIG. 11 described later) ). Therefore, if an approximate line close to the ideal ellipse is calculated, the notch B1 can be detected based on the portion where the approximate line and the main surface edge P23 diverge.

  Therefore, in step S6, the control unit 8 calculates an approximate line (ellipse) approximate to the major surface edge P23 based on the function of the ellipse. More generally, the control unit 8 calculates an approximate line of the major surface edge P23 based on a reference function predetermined as the shape of the contour of the major surface area Ra in the captured image IM11. The reference function referred to here is a function representing the shape of the contour of the main surface area Ra when no defect occurs in the tablet 9, and means a function whose position and size are variables. In the case of a function of an ellipse, for example, the length of the major axis, the length of the minor axis, the extending direction of the major axis, and the center can be adopted as variables. The control unit 8 calculates an ellipse E1 (more specifically, the length of the major axis, the length of the minor axis, and the extending direction and center of the major axis) approximating the major surface edge P23 by the least square method, for example.

  As described above, since the approximate line of the major surface edge P23 is calculated based on the reference function indicating the contour of the major surface area Ra, this approximate line is a line close to the contour of the major surface area Ra. Moreover, in the above-mentioned specific example, the tablet 9 has a substantially disk shape. That is, the main surface 9a of the tablet 9 has a substantially circular shape. Therefore, in the captured image IM11, the periphery of the major surface 9aa ideally has an elliptical shape. In the present embodiment, a function of an ellipse is used as a reference function correspondingly. Therefore, it is possible to appropriately calculate an approximate line close to the contour of main surface area Ra.

  Hereinafter, among the two half ellipses obtained by dividing the ellipse E1 by its major axis, the half ellipse on the main surface 9aa side and the half ellipse on the side surface 9ca are also referred to as half ellipses E11 and E12, respectively. The half ellipses E11 and E12 correspond to approximate lines of the major surface outer edge P2 and the boundary edge P3, respectively.

  Next, in step S7, the control unit 8 calculates an approximation line (semi-ellipse) approximating the side outer edge P1 based on the ellipse E1. For example, while moving the ellipse E1 along the predetermined direction D1, the control unit 8 calculates the ellipse E2 along the side outer edge P1 using the Levenberg-Marquardt (LM) method. The ellipse E2 corresponds to the periphery of the major surface 9b of the tablet 9. Therefore, the control unit 8 divides this ellipse E2 by its major axis, and obtains a semi-elliptic E21 which is farther from the boundary edge P3 among the obtained two semi-elliptics as an approximation line of the side outer edge P1.

  When calculating the ellipse E2, the control unit 8 may reduce the ellipse E1 at a predetermined rate. This is because, in a perspective view such as the captured image IM11, the peripheral edge of the main surface 9b of the tablet 9 is smaller than the peripheral edge of the main surface 9a of the tablet 9 at a predetermined ratio. This predetermined ratio is preset according to the thickness of the tablet 9.

  The control unit 8 does not necessarily calculate the ellipse E2 based on the ellipse E1, and does not need to calculate the semi-elliptic E21 from the ellipse E2. For example, the control unit 8 may calculate the half ellipse E21 using the LM method while obtaining the half ellipse E12 from the ellipse E1 and moving the half ellipse E12 along the predetermined direction D1. In addition, the semi-ellipse E12 may be reduced at a predetermined ratio in calculating the semi-ellipse E21.

  FIG. 11: is a figure which shows roughly an example of the various edge about the tablet 9 which chip | tip B1 produced, and its approximation line. The major surface edge P23 extends along the portion of the outline of the notch B1 on the side surface 9ca and the periphery of the major surface 9aa. In the example of FIG. 11, although the side surface outer edge P1 and the semi-ellipse E21 which is the approximation line are shown in agreement with each other, in fact, these may differ from each other.

  Next, in step S8, the control unit 8 executes an inspection process. This inspection process is a process for detecting chipping that has occurred on the peripheral edge of the main surfaces 9 a and 9 b of the tablet 9. FIG. 12 is a flowchart showing a specific example of this inspection process. First, in step S81, the control unit 8 extracts half ellipses E11 and E12 that are approximate lines of the main surface outside edge P2 and the boundary edge P3 from the ellipse E1 that is an approximate line of the main surface edge P23. Specifically, the control unit 8 calculates half ellipses obtained by dividing the ellipse E1 by its long axis as half ellipses E11 and E12.

  Next, in step S82, control unit 8 determines that distance d between each pixel on boundary edge P3 and half ellipse E12 (see also FIG. 11) is greater than a predetermined threshold (hereinafter referred to as distance threshold) dth. Determine if it is long. The distance threshold dth may be set in advance and stored in the storage medium of the control unit 8, for example. In the example of FIG. 11, the distance d between a certain pixel on the boundary edge P3 and the semi-ellipse E12 is shown. When an affirmative determination is made in step S82, control unit 8 controls the periphery of main surface 9a of tablet 9 (more specifically, the boundary between main surface 9aa and side surface 9ca in captured image IM11) in step S83. Judging that there is a defect in If a negative determination is made, the control unit 8 does not execute step S83.

  FIG. 13 is a flowchart showing a more specific example of the processes of steps S82 and S83. First, in step S801, the control unit 8 initializes the value n to one. The value n is a number indicating a pixel on the boundary edge P3. The pixels on the boundary edge P3 are sequentially numbered sequentially from one end to the other end.

  Next, in step S802, the control unit 8 calculates the distance d between the n-th pixel on the boundary edge P3 (hereinafter referred to as the target pixel) and the half ellipse E12. For example, the control unit 8 calculates the distance between the pixel of interest and each of the pixels on the half ellipse E12, and selects the smallest value as the distance d.

  Next, in step S803, the control unit 8 determines whether the distance d is longer than the distance threshold dth. If a positive determination is made, the control unit 8 determines in step S804 that the pixel of interest is a pixel indicating a contour of a chip, and determines that a defect is generated on the periphery of the main surface 9a of the tablet 9 Do. Next, the control unit 8 executes step S805 described later. On the other hand, if a negative determination is made, the control unit 8 executes step S805 without executing step S804.

  In step S805, the control unit 8 adds 1 to the value n to update the value n. Next, in step S806, control unit 8 determines whether value n is larger than reference value nref. The reference value nref is the total number of pixels constituting the boundary edge P3. That is, it is determined whether the determination is completed for all the pixels on the boundary edge P3. If a negative determination is made in step S806, the control unit 8 executes step S802 again because the determination has not been completed for all the pixels. On the other hand, when an affirmative determination is made in step S806, control unit 8 ends the process.

  In the above-described example, the above determination is made for all pixels on the boundary edge P3. However, when it is not necessary to detect the number of chips, their positions, etc., when one pixel indicating the outline of the chip is detected, the above-mentioned judgment on the remaining pixels may be omitted. The same applies to all inspection processes described below.

  Referring again to FIG. 12, in step S84, control unit 8 determines whether or not the distance between each pixel on main surface outer edge P2 and half ellipse E11 that is an approximation line thereof is longer than distance threshold dth. to decide. When a positive determination is made, in step S85, the control unit 8 has a chip on the periphery of the main surface 9a of the tablet 9 (more specifically, the portion of the captured image IM11 not in contact with the side surface 9ca) I will judge. If a negative determination is made, the control unit 8 does not execute step S85.

  Next, in step S86, the control unit 8 determines whether the distance between each pixel on the side face outer edge P1 and the semi-elliptic curve E21 that is an approximation line thereof is longer than the distance threshold dth. If a positive determination is made, in step S87, the control unit 8 determines that the periphery of the main surface 9b of the tablet 9 (more specifically, a portion appearing in the captured image IM11) is missing. . If a negative determination is made, the control unit 8 does not execute step S87.

  An example of a specific method of steps S84 and S85 and an example of a specific method of steps S86 and S87 are similar to the specific method of steps S82 and S83.

  As mentioned above, according to this tablet inspection apparatus 1, the chipping which arose on the periphery of main surface 9a, 9b of the tablet 9 can be detected.

  The execution order of one set of steps S 82 and S 83, one set of steps S 84 and S 85 and one set of steps S 86 and S 87 may be changed as appropriate. In addition, when it is not necessary to detect the number and position of the chipping, the control unit 8 does not necessarily have to execute all the determinations in steps S82, S84, and S86. When a positive determination is made in any one of the control units 8, the remaining determination may be omitted.

  Further, in the above-described example, the control unit 8 calculates an approximation line (ellipse E1) approximating the major surface edge P23, and extracts the semi-ellipses E11 and E12 from the ellipse E1. However, the control unit 8 calculates an approximate line (semi-elliptic curve E12) of the boundary edge P3 based on a reference function previously determined as the shape of the boundary between the main surface 9aa and the side surface 9ca of the tablet 9 in the captured image IM11. You may Similarly, the control unit 8 approximates the main surface outer edge P2 based on a reference function predetermined as the shape of a portion not in contact with the side surface 9ca of the peripheral surface of the main surface 9aa of the tablet 9 in the captured image IM11. The semi-ellipse E11) may be calculated.

<Inspection processing>
In the above example, for example, when the distance d between one pixel on the boundary edge P3 and the semi-ellipse E12 is longer than the distance threshold dth, the control unit 8 determines that the pixel exhibits a missing outline ( Steps S802 to S804). That is, when the one pixel is separated from the semi-ellipse E12 by a distance longer than the distance threshold dth, it is determined that the pixel exhibits a missing outline. However, when a notch B1 occurs, referring also to FIG. 11, a plurality of continuous pixels on the boundary edge P3 are separated from the semi-ellipse E12 at a distance longer than the distance threshold dth. That is, if only one pixel is separated from the semi-ellipse E12 by a distance longer than the distance threshold dth, that pixel may be noise instead of indicating the missing B1. Therefore, in this case, it is suppressed to erroneously detect such noise as missing.

  Specifically, the control unit 8 determines whether a plurality of pixels separated from the semi-ellipsoid E12 at a distance d longer than the distance threshold dth are continuous on the boundary edge P3, and an affirmative determination is made. It is determined that the group of consecutive pixels show the outline of chipping B1, and the periphery of the main surface 9a of the tablet 9 (more specifically, the boundary between the main surface 9aa and the side surface 9ca of the captured image IM11) It is determined that a missing B1 has occurred.

  FIG. 14 is a flowchart showing an example of a specific method of such inspection processing. First, in step S811, the control unit 8 initializes the values n and m to 1 and 0, respectively. The value m indicates the number of continuous pixels on the boundary edge P3 which are pixels separated from the semi-ellipse E12 by a distance longer than the distance threshold dth, as will be apparent from the following description.

  Next, the control unit 8 executes steps S812 and S813 in this order. Steps S812 and S813 are the same as steps S802 and S803, respectively. When an affirmative determination is made in step S813, in step S814, the control unit 8 adds 1 to the value m to update the value m.

  Next, in step S815, the control unit 8 adds 1 to the value n to update the value n. Next, in step S816, control unit 8 determines whether value n is larger than reference value nref. That is, the control unit 8 determines whether the process has been performed on all the pixels on the boundary edge P3. If a negative determination is made, the control unit 8 executes step S812 again to make a determination on the next pixel. On the other hand, if an affirmative determination is made, the control unit 8 ends the process.

  If a negative determination is made in step S813, in step S817, control unit 8 determines whether value m is larger than a threshold (hereinafter, referred to as a continuous threshold) mth. For example, the continuous threshold mth may be set in advance and stored in a storage medium of the control unit 8.

  If an affirmative determination is made in step S 817, in step S 818, the control unit 8 causes the group of the (n−m + 1) -th pixel to the (n−1) -th pixel to indicate a missing outline. It is determined that there is a chipping B1 at the periphery of the main surface 9a (more specifically, the boundary between the main surface 9aa and the side surface 9ca in the captured image IM11). Next, in step S819, the control unit 8 initializes the value m to 0, and executes step S815. If a negative determination is made in step S817, the control unit 8 executes step S819 without executing step S818.

  According to this inspection process, the value m is initialized to zero when a pixel having a distance d shorter than the distance threshold dth is detected (step S819), and pixels having a distance d longer than the distance threshold dth continue Each time it is detected, it is incremented (step S815). Therefore, the value m indicates the number of consecutive pixels whose distance d is longer than the distance threshold dth. Then, when the value m is larger than the continuous threshold value mth, the control unit 8 determines that a chipping has occurred (steps S 817 and S 818). This makes it possible to suppress chipping error detection and detect chipping with higher accuracy.

  This inspection process is also applicable to the side outer edge P1 and the main surface outer edge P2.

<Boundary edge>
In the above example, in the search from the line L1 to the line L2 in each row of the search area R1, the edge pixel detected first is grasped as a component of the boundary edge P3 (see FIG. 9). Therefore, among the chipped edge P ′, a pixel on the edge Pc ′ on the line L1 side is adopted as a component of the boundary edge P3. Therefore, the component of the boundary edge P3 is biased to the edge Pc 'of the chipped edge P'. As a result, the ellipse E1 (one set of half ellipses E11 and E12) approximate to the major surface edge P23 is easily deviated from the contour of the major surface region Ra.

  Here, it is contemplated to calculate an ellipse E1 closer to the outline of the main surface area Ra by devising a method of searching for the boundary edge P3. Specifically, focusing on the distribution of pixel values of the defect area in the captured image IM11, the components of the boundary edge P3 are an edge P 'on the line L1 side and an edge Pa' on the line L2 side. It is contemplated to identify the boundary edge P3 so as to be distributed.

  The chipped surface of the tablet 9 is rougher than the surface roughness of the main surface 9a and the side surface 9c, and the luminance component in the defect area in the captured image IM11 is dispersed. Therefore, the luminance component also varies in the outline (edge P ') of the defect area. Therefore, the pixel values on the edge Pa 'in the captured image IM11 also vary in a certain range, and the pixel values on the edge Pc' also vary in a similar range.

  Therefore, the control unit 8 searches for a pixel in the search area R1 of the edge image, and for which the pixel value in the corresponding captured image IM11 is larger than a predetermined threshold (hereinafter, referred to as a brightness threshold). The brightness threshold is set in advance in accordance with the brightness of the major surface 9 aa of the tablet 9. For example, the brightness threshold is preset to a value within the above range. Such brightness threshold can be set, for example, by simulation or experiment. The brightness threshold may be stored in, for example, a storage medium of the control unit 8. Hereinafter, an example of a specific operation will be described.

  FIG. 15 is a flowchart showing an example of a search process by the control unit 8. Compared to FIG. 10, the control unit 8 further executes step S57. This step S57 is executed when an affirmative determination is made in step S52. In step S57, the control unit 8 determines whether the pixel value of the Nth row and Mth pixel in the search area R1 of the captured image IM11 is larger than the brightness threshold.

  When a negative determination is made in step S57, the control unit 8 executes step S53, and when a positive determination is made, the control unit 8 executes step S54.

  According to this, even if it is an edge pixel in the search area R1, if the pixel value of the pixel of the captured image IM11 corresponding to the edge pixel is smaller than the brightness threshold, the edge pixel is the boundary edge P3. If the pixel value of the pixel of the captured image IM11 is larger than the brightness threshold, the edge image is recognized as a component of the boundary edge P3.

  As a result, pixels grasped as components of the boundary edge P3 are dispersed on the edge P '. FIG. 16 is a view schematically showing an example of an edge in an edge image when a crack is generated in the boundary between the major surface 9 aa and the side surface 9 ca of the tablet 9. Also in the example of FIG. 16, some of the pixels grasped as the boundary edge P3 are schematically shown by black circles. As illustrated in FIG. 16, the pixels are dispersed at the edges Pa ′ and Pc ′ of the edge P ′. In other words, the brightness threshold is set so that the pixel grasped as the boundary edge P3 is not biased to only one side at the edge P '. As a more specific example, the brightness (for example, the average value, median value, maximum value or minimum value of pixel values (or brightness values) of the main surface 9 aa of the tablet 9) applies to the side surface 9 ca of the tablet 9. When the brightness is higher than the brightness, the brightness of the main surface 9 aa is adopted as the brightness threshold, and when the brightness of the main surface 9 aa of the tablet 9 is lower than the brightness of the side surface 9 ca of the tablet 9, the brightness The brightness of the side 9 ca is adopted as the threshold.

  A semi-elliptic E11 approximating such boundary edge P3 becomes a semi-elliptical closer to the periphery of the major surface 9aa of the tablet 9, and an ellipse E1 approximate to the major surface edge P23 is an ellipse closer to the periphery of the major surface 9aa of the tablet 9 It becomes.

  FIG. 17: is a figure which shows roughly an example of the various edge about the tablet 9 which notch | chip B1 produced, and its approximation line. Since the components of the boundary edge P3 are distributed to the edges Pa 'and Pc' at the chipped edge P ', in the example of FIG. 17, the chipped edge P' is partially identified as a component of the boundary edge P3. The chipped edge P 'is shown in dashed lines for the sake of illustration. Further, in the example of FIG. 17, the main surface outer edge P2 and the semi-ellipse E11 are shown to match each other, and the side outer edge P1 and the semi-ellipse E21 are shown to match each other. The boundary edge P3 is shown to coincide with the semi-ellipse E12 in parts other than the chipped edge P '. In practice, these may be different from one another.

  As can be understood from the comparison of FIGS. 11 and 17, the distance d between each pixel on the boundary edge P3 and the semi-ellipse E12 is calculated larger at the missing edge P '. Therefore, chipping B1 is easier to detect. In other words, the chip B1 can be detected with higher accuracy.

  Moreover, since the components of the boundary edge P3 are dispersed at the missing edge P ', both the pixels on the edge Pa' and the pixels on the edge Pc 'can be used to detect the missing B1. Thereby, even if the chipping B1 is formed to be biased to the main surface 9aa side, that is, the edge Pc 'is not projected so much to the side surface 9ca side, but is projected to the main surface 9aa side Even if there is, the chipping B1 can be detected. The details will be described below.

  FIG. 18 is a view schematically showing an example of various edges and their approximate lines when the notch B1 does not project to the side surface 9ca side. If the notch B1 does not extend much toward the side surface 9ca, the distance d between each pixel on the edge Pc 'and the semi-ellipse E12 becomes short. Then, depending on the shape of the notch B1, the distance d for all the pixels on the edge Pc 'may be shorter than the distance threshold dth. At this time, if the component of the boundary edge P3 is biased to the edge Pc 'by employing the search processing of FIG. 9, the chip B1 can not be detected in the subsequent inspection processing.

  On the other hand, if the notch B1 protrudes to the main surface 9aa side, as shown in FIG. 18, the distance d between the pixel on the edge Pa 'and the semi-ellipse E12 becomes longer than the distance threshold dth. Therefore, using the search processing of FIG. 16 in which the components of the boundary edge P3 are distributed to both the edges Pa 'and Pc', the chip B1 can be detected in the subsequent inspection processing. This is because, in this inspection process, it is determined whether the distance d between the pixel on the edge Pa 'of the boundary edge P3 and the half ellipse E12 and the distance threshold dth are large (steps S82 and S83).

<Center line of search area>
In the above example, the center line L0 of the search area R1 is described as a line obtained by moving the side outer edge P1, but the side outer edge P1 may be enlarged at a predetermined magnification during this movement. Strictly speaking, the boundary edge P3 is larger than the side outer edge P1 at a predetermined magnification.

Modified example.
<Principal surface of tablet>
In the above-mentioned example, the tablet 9 conveyed in the posture where the principal surface 9 b faces the conveyance belt 41 side was described as the inspection object. When the tablet 9 is transported in a posture in which the major surface 9 a of the tablet 9 faces the transport belt 41, the tablet inspection apparatus 1 performs an appearance inspection on the major surface 9 b and the side surface 9 c of the tablet 9.

  For example, after the appearance inspection on the tablet 9, the transport posture of the tablet 9 may be reversed, and the appearance inspection on the tablet 9 may be performed in that state. According to this, an appearance inspection can be performed on the entire surface (main surfaces 9a and 9b and side surface 9c) of the tablet 9.

<Shape of tablet>
In the above-mentioned example, the tablet 9 had a substantially disc shape. For example, a so-called flat lock or a lock with R can be adopted as the disk shape. However, the tablet 9 is not necessarily limited to the disk shape. That is, the main surfaces 9a and 9b do not necessarily have to have a circular shape. Since the shapes of the main surfaces 9a and 9b are known, the shape of the periphery of the main surface 9a (or the main surface 9b) that will appear in the captured image IM11 can be determined in advance by a reference function. Although this reference function indicates the shape, it is a function whose size and position are variables. The reference function may be stored in advance in, for example, a storage medium of the control unit 8. The control unit 8 may generate an edge image from the captured image IM11, and obtain an approximate line of the major surface edge included in the edge image based on the reference function.

  As mentioned above, although the tablet inspection method and the tablet inspection device were explained in detail, the above-mentioned explanation is illustration in all the aspects, and this indication is not limited to it. The various modifications described above can be combined and applied as long as they do not contradict each other. And, it is understood that many variations not illustrated may be envisaged without departing from the scope of the present disclosure.

1 tablet inspection device 5 imaging unit (imaging head)
8 Image processing unit (control unit)
9 tablets 9a first main surface (main surface)
9b Second main surface (main surface)
9c Side E1 Second approximate line (ellipse)
E11 Third approximate line (half-elliptic)
E12 First approximation line (half-elliptic)
E21 Fourth approximation line (half-elliptic)
IM1 captured image P0 Tablet edge P1 Side outer edge P2 Main surface outer edge P3 Boundary edge P23 Main edge R1 Search area Ra Main area Rc Side area TR Tablet area

Claims (8)

A tablet inspection method for inspecting the appearance of a tablet having a pair of first and second main surfaces and a side surface, comprising:
Imaging a tablet to generate an imaged image in which both the first major surface and the side surface are captured;
A boundary edge corresponding to a boundary between a main surface area and a side surface area respectively occupied by the first main surface and the side surface of the tablet in the captured image is specified, and a first approximate line approximating the boundary edge is Calculating (b) based on a function indicating the shape of the boundary in the captured image;
A step of determining that the periphery of the first main surface of the tablet is chipped when the distance between each pixel on the boundary edge and the first approximate line is longer than a predetermined threshold (c And a tablet inspection method. The tablet inspection method according to claim 1, wherein
The main surface area and the side surface area constitute a tablet area occupied by the tablet in the captured image,
In the step (b),
Performing an edge detection process on the captured image to generate an edge image (b1);
Identifying a tablet edge corresponding to the contour of the tablet area from the edge image (b2);
A main surface outer edge and a side surface outer edge respectively corresponding to a part of the periphery of the first main surface in the captured image that is a part of the contour of the tablet region and the periphery of the second main surface in the captured image Extracting from the tablet edge (b3),
Searching for a pixel in a search area at a predetermined distance from the side outer edge along the predetermined direction in the edge image to specify the boundary edge (b4);
Calculating a second approximate line of the main surface outer edge and the pair of main surface edges that are one set of the boundary edge based on the function indicating the shape of the contour of the main surface area in the captured image;
Extracting the first approximate line of the boundary edge from the second approximate line (b6). The tablet inspection method according to claim 2, wherein
The tablet has a substantially disc shape,
The tablet inspection method, wherein the function is a function indicating an ellipse, and the second approximate line is an ellipse. A tablet inspection method according to claim 2 or claim 3, wherein
In the step (b4),
The tablet inspection method which is a pixel in the search area of the edge image, and searches for a pixel whose pixel value of the pixel of the captured image corresponding to the pixel is larger than a predetermined threshold to specify the boundary edge. A tablet inspection method according to claim 3 or claim 4, wherein
In the step (b4),
The tablet inspection method which searches the pixel from said side face outer edge toward said main surface outer side edge in said search area, and specifies said border edge. The tablet inspection method according to any one of claims 2 to 5, wherein
Extracting a third approximate line of the main surface outside edge from the second approximate line of the main surface edge calculated in the step (b5);
A step of determining that the periphery of the first main surface of the tablet is chipped when the distance between each pixel on the main surface outer edge and the third approximate line is longer than a predetermined threshold value And a tablet inspection method. A tablet inspection method according to any one of claims 2 to 6,
Extracting a fourth approximate line of the side surface outer edge from the second approximate line of the main surface edge calculated in the step (b5);
Determining that the periphery of the second main surface of the tablet is chipped when the distance between each pixel on the side outer edge and the fourth approximate line is longer than a predetermined threshold; , A tablet inspection method. A tablet inspection apparatus for inspecting the appearance of a tablet having a pair of first and second main surfaces and a side surface, the tablet inspection apparatus comprising:
An imaging unit for imaging a tablet to generate an imaged image in which both the first main surface and the side surface are captured;
And an image processing unit,
The image processing unit
Identifying a boundary edge corresponding to a boundary between the main surface area and the side surface area respectively occupied by the first main surface and the side surface of the tablet in the captured image;
A first approximate line approximating the boundary edge is calculated based on a function indicating the shape of the boundary in the captured image,
A tablet test in which it is determined that the periphery of the first main surface of the tablet is chipped when the distance between each pixel on the boundary edge and the first approximate line is longer than a predetermined threshold value. apparatus.

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