Coating layer inspection device and coating layer inspection method

Abstract

[Problem] To provide a coating layer inspecting device and a coating layer inspecting method with which the defectiveness of a coating layer of a subject can be determined with a high degree of accuracy. [Solution] In a coating layer inspecting device 10 for inspecting a coating layer 102 formed on a surface of a subject, a processing unit 42 includes: a quantifying unit 50 for quantifying gradation information of each pixel; a gradation average value calculating unit 52 for calculating a gradation average value; a first shade determining unit 53 for determining whether the gradation average value is at least equal to a first threshold, and if the determination is affirmative, leaving a grayscale image as a pass candidate; and a first upper limit determining unit 54 for determining whether the number of pixels of which the gradation is at least equal to a first threshold is at most equal to a first upper limit prescribed value, if the determination is affirmative, leaving the grayscale image as a pass candidate, and if the determination is negative, determining that the grayscale image is a failure.

Description

[Technical Field]

[0001] The present invention relates to a coating layer inspection device and a coating layer inspection method for inspecting a coating layer formed on the surface of an object. [Background technology]

[0002] In recent years, balloon catheters have been used to treat lesions (stenoses) that have developed in biological lumens. A balloon catheter typically includes a long shaft and a radially expandable balloon located distal to the shaft. The deflated balloon can be expanded after passing through a narrow biological lumen to a target location within the body, thereby widening the lesion.

[0003] However, forcibly expanding the lesion may cause excessive proliferation of smooth muscle cells, leading to new narrowing (restenosis) at the lesion. For this reason, drug-eluting balloons (DEBs), which have a coating of drugs on the surface of the balloon to suppress narrowing, have recently been used. When a drug-eluting balloon is expanded, it releases the drug coated on its surface into the lesion, thereby suppressing restenosis.

[0004] From the viewpoint of drug release and tissue migration, it is preferable that the coating layer containing the drug on the surface of the balloon be formed uniformly in a desired amount. Furthermore, it is preferable that the coating layer have a uniform crystal morphology and crystal distribution. Therefore, it is desirable to be able to determine the state of the formed coating layer.

[0005] For example, Patent Document 1 describes a method for capturing an image of the external appearance of a test object and identifying foreign matter from the resulting image. The method described in Patent Document 1 detects foreign matter areas from a binary image obtained by capturing an image of the surface of a light-transmitting material, differentiates the area in two stages, and classifies whether the foreign matter is removable or not based on the length of the detected edge. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-8564 Summary of the Invention [Problem to be solved by the invention]

[0007] The device and method described in Patent Document 1 can identify foreign matter in a test object, but it is difficult to determine the overall defectivity of the test object with high accuracy.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a coating layer inspection device and a coating layer inspection method that can determine the defectivity of a coating layer of a test object with high accuracy. [Means for solving the problem]

[0009] The coating layer inspection device according to the present invention, which achieves the above object, is a coating layer inspection device for inspecting a coating layer formed on the surface of an object to be inspected, and includes an imaging unit that images the coating layer to create image data, and a processing unit that performs image processing. The processing unit includes a digitizing unit that grayscales the image data to create a grayscale image and digitizes the gradation information of each pixel so that it increases from black to white, an area specifying unit that specifies a determination target area where the coating layer of the object to be inspected is formed, and a gradation averager that calculates the gradation average value of all pixels present in the determination target area. The image processing device has a calculation unit, a first gradation judgment unit that judges whether the average gradation value is equal to or greater than a predetermined first threshold value or whether it exceeds the first threshold value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and a first upper limit judgment unit that judges whether the number of pixels in the judgment target area whose gradation is equal to or greater than the first threshold value or the number of pixels that exceed the first threshold value is equal to or less than a predetermined first upper limit value or whether it is less than the first upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

[0010] The coating layer inspection method of the present invention, which achieves the above-mentioned object, is a coating layer inspection method for inspecting a coating layer formed on the surface of a test object, and includes the steps of imaging the coating layer to obtain image data, grayscaling the image data to form a gradation image and quantifying the gradation information of each pixel so that it increases from black to white, identifying a target area of ​​the test object where the coating layer is formed, calculating the average gradation of all pixels present in the target area, a first gradation judgment step of judging whether the average gradation is greater than or equal to a predetermined first threshold or whether it exceeds the first threshold, and if the judgment is positive, leaving the gradation image as a candidate for passing, and a first upper limit judgment step of judging whether the number of pixels in the target area whose gradation is greater than or equal to the first threshold or exceeds the first threshold is less than or equal to a predetermined first upper limit specified value or whether it is less than the first upper limit specified value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and judging the gradation image as a failure if the judgment is negative. [Effects of the Invention]

[0011] The coating layer inspection device configured as described above uses the first shade judgment unit to select inspection objects that are judged to have a strong white color and to have more than a predetermined amount of coating layer material that can be passed, and the first upper limit judgment unit to exclude inspection objects with large areas of too much coating layer material.As a result, this coating layer inspection device judges the defectivity of the coating layer based on multiple judgments, and can therefore judge the defectivity of the coating layer of the inspection object with high accuracy.

[0012] The coating layer inspection device may also include a third upper limit judgment unit that judges whether the number of pixels in the judgment target area whose gradation is equal to or less than a predetermined third threshold or the number of pixels whose gradation is less than the third threshold is equal to or less than a predetermined third upper limit, and if the judgment is positive, keeps the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image to be unacceptable. This allows the third upper limit judgment unit to exclude specimens that have large areas with too little coating layer material. Because this coating layer inspection device judges the defectivity of the coating layer based on multiple judgments, it can more accurately judge the defectivity of the coating layer of the specimen.

[0013] The coating layer inspection device may further include a second gradation judgment unit that, when the first gradation judgment unit makes a negative judgment, judges whether the average gradation value is equal to or greater than a predetermined second threshold value that is smaller than the first threshold value, and leaves the gradation image as a candidate for acceptance if the judgment is positive, and judges the gradation image as a rejection if the judgment is negative, and a second upper limit judgment unit that judges whether the number of pixels whose gradation is equal to or greater than the second threshold value in the judgment target region is equal to or less than a predetermined second upper limit value, and leaves the gradation image as a candidate for acceptance if the judgment is positive, and judges the gradation image as a rejection if the judgment is negative. This allows the inspection device to select, by the second gradation judgment unit, inspected objects that are judged by the second upper limit judgment unit to have a weak white color but that have at least a predetermined amount of coating layer material that can be accepted, and to exclude, by the second upper limit judgment unit, inspected objects that have large areas with too much coating layer material. Therefore, this inspection device can use desirable thresholds and specified values ​​according to the average gradation value to accurately exclude quality that should be judged as unacceptable, and can prevent specimens that should be judged as good from being judged as unacceptable.

[0014] The coating layer inspection device may also include a fourth upper limit judgment unit that judges whether the number of pixels in the judgment target area whose gradation is equal to or less than a predetermined fourth threshold or the number of pixels whose gradation is less than the fourth threshold is equal to or less than a predetermined fourth upper limit, and if the judgment is positive, retains the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image to be unacceptable. This allows the inspection device to use the fourth upper limit judgment unit to exclude specimens with large areas where the coating layer material is too thin. Therefore, the inspection device can use desirable thresholds and predetermined values ​​according to the average gradation value to accurately exclude specimens that should be judged as unacceptable, and prevent specimens that should be judged as non-defective from being judged as unacceptable.

[0015] The coating layer inspection device may have a gradation difference judgment unit that judges whether the number of pixels in the judgment target area whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold or the number of pixels whose gradation difference exceeds the gradation difference threshold is equal to or less than a predetermined gradation difference specified value, and if the judgment is positive, keeps the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image to be unacceptable. This allows the inspection device to exclude specimens whose coating layer is judged by the gradation difference judgment unit to have large local changes. This allows the inspection device to more accurately judge the defectivity of the coating layer of the specimen.

[0016] The test object may be a balloon that can be inserted into a biological lumen, and the coating layer may contain a drug. This allows the inspection device to determine with high accuracy whether the coating layer containing the drug on the surface of the balloon is defective.

[0017] The coating layer inspection method configured as described above selects, in the first density determination step, an inspection object that is determined to have a coating layer material in an amount greater than or equal to a predetermined amount that allows the inspection object to be accepted because of its strong white color, and excludes, in the first upper limit determination step, inspection objects in which there are large areas with too much coating layer material. Therefore, this coating layer inspection method determines the defect of the coating layer through multiple determination steps, and can therefore determine the defect of the coating layer of the inspection object with high accuracy.

[0018] The coating layer inspection method may include a third upper limit judgment step of judging whether the number of pixels in the judgment target area whose gradation is equal to or less than a predetermined third threshold or the number of pixels whose gradation is less than the third threshold is equal to or less than a predetermined third upper limit, and if the judgment is affirmative, retaining the grayscale image as a candidate for passing, and if the judgment is negative, judging the grayscale image to be unacceptable. This allows the coating layer inspection method to exclude specimens with large areas where the coating layer material is too thin by the third upper limit judgment step. Therefore, since the coating layer inspection method judges the defect of the coating layer through multiple judgment steps, it can more accurately judge the defect of the coating layer of the specimen. Note that either the first upper limit judgment step or the third upper limit judgment step may be performed first.

[0019] The coating layer inspection method may further include a second grayscale judgment step of, if the first grayscale judgment step results in a negative judgment, judging whether the average grayscale value is equal to or greater than a predetermined second threshold value that is smaller than the first threshold value, and retaining the grayscale image as a candidate for passing if the judgment is positive, and judging the grayscale image as a rejection if the judgment is negative, and a second upper limit judgment step of, if the number of pixels whose grayscale is equal to or greater than the second threshold value in the judgment target region is equal to or less than a predetermined second upper limit value, and retaining the grayscale image as a candidate for passing if the judgment is positive, and judging the grayscale image as a rejection if the judgment is negative. This allows the second grayscale judgment step to select inspected objects that are weakly white but are judged to have at least a predetermined amount of coating layer material that can be passed, and the second upper limit judgment step to exclude inspected objects with large areas of too much coating layer material. Therefore, this inspection method can use desirable thresholds and specified values ​​according to the average gradation value to accurately exclude quality that should be judged as unacceptable, and can prevent specimens that should be judged as good from being judged as unacceptable.

[0020] The coating layer inspection method may include a fourth upper limit determination step of determining whether the number of pixels in the determination target area whose gradation is equal to or less than the fourth threshold is equal to or less than a predetermined fourth upper limit, and if the determination is affirmative, retaining the grayscale image as a candidate for passing, and if the determination is negative, determining the grayscale image as a failing candidate. This allows the inspection method to exclude, by the fourth upper limit determination step, inspection objects with large areas where the coating layer is too thin. Therefore, by using a desirable fourth upper limit value according to the average gradation value, the inspection method can accurately exclude inspection objects that should be determined to be failing, and can prevent inspection objects that should be determined to be good from being determined to be failing.

[0021] The coating layer inspection method may further include a gradation difference determination step, at any point after the first gradation determination step, of determining whether the number of pixels in the determination target area whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold or whether the number of pixels whose gradation difference with adjacent pixels exceeds the gradation difference threshold is equal to or less than a predetermined gradation difference specified value, and whether the gradation image is judged to be acceptable if the determination is affirmative, and judging the gradation image to be unacceptable if the determination is negative. This allows the inspection method to exclude specimens whose coating layer is judged to have significant local variations in the gradation difference determination step. This allows the inspection method to more accurately determine the defectivity of the coating layer of the specimen.

[0022] The test object may be a balloon that can be inserted into a biological lumen, and the coating layer may contain a drug. This allows the inspection method to determine with high accuracy whether the coating layer containing the drug on the surface of the balloon is defective. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing a coating layer inspection device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a front view showing a balloon as a test object. [Figure 3]10 is a flowchart showing the flow of processing in a processing unit. [Figure 4] 10A and 10B are schematic diagrams showing the state of the coating layer of a balloon, in which (A) is the coating layer of a first example in which the first shading judgment unit judged it to be negative, (B) is the coating layer of a second example in which the first shading judgment unit judged it to be negative, (C) is the coating layer of a third example in which the first shading judgment unit judged it to be negative, (D) is the coating layer that was rejected by the first upper limit judgment unit, (E) is the coating layer that was rejected by the third upper limit judgment unit and the fourth upper limit judgment unit, and (F) is the coating layer that was judged to be passed. [Figure 5] FIG. 2 is a plan view showing an example of a plurality of pixels arranged two-dimensionally. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensional proportions in the drawings may be exaggerated for convenience of explanation and may differ from the actual proportions. Furthermore, in this specification and drawings, components having substantially the same functions are designated by the same reference numerals, and redundant explanations will be omitted.

[0025] As shown in Figures 1 and 2, a coating layer inspection device 10 according to an embodiment of the present invention is used to determine whether a coating layer 102 disposed on the surface of a balloon 101 of a drug-eluting balloon catheter 100 is a non-defective product.

[0026] The surface of the balloon 101 is smooth and non-porous, but may be porous. The balloon 101 is formed of a material that has a certain degree of flexibility and a certain degree of hardness so that it expands upon reaching a blood vessel, tissue, or the like, and releases a drug from the coating layer 102 on its surface. Specifically, at least the surface of the balloon 101 on which the coating layer 102 is provided is preferably made of a resin. Examples of materials that can be used for at least the surface of the balloon 101 include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomers, and mixtures of two or more of these; thermoplastic resins such as soft polyvinyl chloride resin, polyamide, polyamide elastomer, nylon elastomer, polyester, polyester elastomer, polyurethane, and fluororesin; silicone rubber; and latex rubber.

[0027] The coating layer 102 is formed to contain a drug. The coating layer 102 may also contain an additive. The drug is not particularly limited, but is preferably a water-insoluble drug. For example, the coating layer 102 is formed from a plurality of minute drug crystals. The drug may be in the form of crystal, non-crystalline (amorphous), or a mixture thereof. The crystal or non-crystalline particles may be arranged in a regular pattern in the coating layer 102, or may be arranged irregularly. The crystalline form is not particularly limited, and may be, for example, a columnar form elongated in one direction, a flat plate form, an irregular block form, or the like.

[0028] Some preferred examples of water-insoluble drugs include immunosuppressants, e.g., cyclosporines, including cyclosporine, immunostimulants such as rapamycin, anti-cancer drugs such as paclitaxel, antiviral or antibacterial drugs, antineoplastic agents, analgesics and anti-inflammatory drugs, antibiotics, antiepileptics, anxiolytics, antiparalytics, antagonists, neuron blocking agents, anticholinergics and cholinergic agents, antimuscarinic and muscarinic agents, antiadrenergic agents, antiarrhythmic agents, antihypertensive agents, hormonal agents, and nutritional agents.

[0029] The water-insoluble drug is preferably at least one selected from the group consisting of rapamycin, paclitaxel, docetaxel, and everolimus. As used herein, rapamycin, paclitaxel, docetaxel, and everolimus include their analogs and / or derivatives as long as they have similar pharmacological effects. For example, paclitaxel and docetaxel are in an analogue relationship. Rapamycin and everolimus are derivatives. Of these, paclitaxel is more preferred.

[0030] Next, we will explain the coating layer inspection device 10. The coating layer inspection device 10 includes an illumination device 20 that illuminates a balloon 101, which is an object to be inspected, an imaging unit 30 that photographs the illuminated object, creates image data, and transmits the data as an electrical signal, a processing device 40 that receives the image data from the imaging unit 30, a display device 70 that displays the determination results from the processing device 40, and an input device 80 that can input information to the processing device 40.

[0031] The illumination device 20 illuminates the subject. It is desirable that the illumination device 20 uniformly illuminate the determination target area A on the surface of the subject. The illuminance of the illumination device 20 is 100 lx or more near the surface of the subject for determination, but is preferably 1,000 to 200,000 lx, and even more preferably 20,000 to 40,000 lx, as this allows for uniform illumination of the surface of the subject. The type of light source is not important, and any light source that can ensure the above-mentioned illuminance may be used, such as an incandescent bulb, fluorescent lamp, halogen lamp, HID lamp, LED lamp, organic LED lamp, or HID halogen lamp. HID halogen lamp is a general term for high-pressure mercury lamps and the like, which have higher brightness than incandescent lamps and are used, for example, for lighting automobiles and trains.

[0032] The imaging unit 30 captures an image of the subject illuminated by the illumination device 20, creates a digital image, and transmits it to the processing device 40. The imaging unit 30 includes, for example, a lens for forming an image of the light reflected from the subject, and a CCD camera for converting the formed image of the subject into an electrical signal. The greater the number of pixels, the clearer the boundaries between light and dark colors, improving the accuracy of the determination. Therefore, a camera with 200,000 or more pixels is capable of determination, but preferably 400,000 to 10 million pixels, and even more preferably 1 million to 5 million pixels. A shutter speed of 1 / 15 or faster is capable of determination, but preferably 1 / 20 to 1 / 100,000, and even more preferably 1 / 30 to 1 / 100.

[0033] The display device 70 is a device that receives and displays signals output from the processing device 40, and includes, for example, a monitor. The display device 70 displays images captured by the imaging unit 30, processed images, and the determination result as to whether the subject is a non-defective product.

[0034] The input device 80 is a device that can input information to the processing device 40, and is, for example, a keyboard, a mouse, a connector that can connect a storage medium or another computer, etc. The input device 80 is used by the user to perform various operations.

[0035] The processing device 40 includes an interface 41 for receiving the electrical signal from the imaging unit 30 as image data, and a processing unit 42 for performing arithmetic processing. The processing device 40 is, for example, a computer.

[0036] The processing unit 42 has a physical configuration including a memory circuit and an arithmetic circuit. The memory circuit stores programs and various parameters. The arithmetic circuit is, for example, a CPU (Central Processing Unit), which reads the programs and various parameters from the memory circuit and performs preprocessing on the image, such as arithmetic processing, binarization, contrast adjustment, and noise control.

[0037] The processing unit 42 functionally comprises a digitizing unit 50, an area specifying unit 51, a gradation average calculation unit 52, a first shade judgment unit 53, a first upper limit judgment unit 54, a gradation difference judgment unit 55, and a third upper limit judgment unit 56. The processing unit 42 further comprises a second shade judgment unit 57, a second upper limit judgment unit 58, a fourth upper limit judgment unit 59, and a result output unit 60. The digitizing unit 50, the area specifying unit 51, the gradation average calculation unit 52, the first shade judgment unit 53, the first upper limit judgment unit 54, the gradation difference judgment unit 55, the third upper limit judgment unit 56, the second shade judgment unit 57, the second upper limit judgment unit 58, the fourth upper limit judgment unit 59, and the result output unit 60 will be described in detail together with the description of the inspection method, which will be described later.

[0038] Next, a coating layer inspection method using the coating layer inspection device 10 according to the embodiment will be described with reference to the flowchart of the processing unit 42 shown in FIG.

[0039] The imaging unit 30 captures an image of the balloon 101, which is the subject illuminated by the illumination device 20, and transmits the resulting digital image as an electrical signal to the processing device 40. The electrical signal of the digital image is transmitted to an interface 41 of the processing device 40. The interface 41 captures the electrical signal from the imaging unit 30 as image data.

[0040] Next, the processing unit 42 digitizes the gradation information of each pixel using the digitizing unit 50 (step S10). The digitizing unit 50 converts the captured image data into a grayscale image. The gradation image digitizes the brightness of each pixel using 256 gradations, for example, from 0 to 255. Therefore, when the digitized gradation is 0, the pixel is black, and when the digitized gradation is 255, the pixel is white. The digitized gradation of each pixel is stored in a storage device. When the subject is a balloon 101, the area where the drug-containing coating layer 102 is formed strongly reflects light and becomes more white, with the gradation approaching 255. On the other hand, the area where the coating layer 102 of the balloon 101 is not formed is nearly transparent and therefore hardly reflects light, so becomes more black (less white), with the gradation approaching 0.

[0041] Next, the processing unit 42 causes the region identification unit 51 to identify, from the grayscale image, a determination target region A (see FIG. 2 ) where the coating layer 102 of the balloon 101, which is the subject, is to be formed (step S11). The grayscale image includes the determination target region A. If the position of the balloon 101 relative to the imaging unit 30 is approximately fixed, the determination target region A can be fixedly set within the field of view of the imaging unit 30. Note that the method for identifying the determination target region A is not particularly limited. For example, the determination target region A in the grayscale image may be separated from the background by comparing the digitized gradation of each pixel with an appropriate threshold. Alternatively, the determination target region A may be manually identified by displaying the grayscale image on the display device 60.

[0042] Next, the processing unit 42 calculates the average gradation value of all pixels present in the determination target area A using the average gradation value calculation unit 52 (step S12). The average gradation value is the sum of the gradations of all pixels present in the determination target area A divided by the number of pixels.

[0043] Next, the processing unit 42 determines, via the first shading judgment unit 53, whether the average gradation value is equal to or greater than a predetermined first threshold (step S13). Alternatively, the first shading judgment unit 53 may determine whether the average gradation value exceeds a predetermined first threshold. The first threshold is a value greater than 0 and less than 255. The first threshold is determined through experiments or the like as a threshold for determining whether the overall amount of material in the coating layer 102 on the surface of the balloon 101 is equal to or greater than a predetermined desired amount. If the judgment is affirmative, the first shading judgment unit 53 determines that the gradation is strong in white and that the overall amount of material in the coating layer 102 is equal to or greater than a predetermined amount, and leaves the shading image as a candidate for acceptance. If the judgment is negative, the first shading judgment unit 53 determines that the gradation is weak in white and that the overall amount of material in the coating layer 102 is less than the predetermined amount, and transfers the judgment of the shading image to the second shading judgment unit 57, which will be described later. Examples of negative judgments by the first density judgment unit 53 include a case where the crystalline form of the drug varies depending on the region as shown in Figure 4(A), a case where the drug is not sufficiently loaded on the balloon 101 as shown in Figure 4(B), and a case where the drug is not sufficiently loaded on the balloon 101 and crystal clumps 103 are present over a wide area as shown in Figure 4(C). As shown in Figures 4(B) and (C), the balloon 101 may have a defective coating layer 102, resulting in a loss of the coating layer 102 and an exposed portion 105 where the surface of the balloon 101 itself is exposed. When an exposed portion 105 is formed, there may be cases where crystal clumps 103 are present or where no crystal clumps 103 are present.

[0044] If the first gradation determination unit 53 determines that the first upper limit determination unit 54 in the processing unit 42 determines whether the number of pixels in the determination target area A whose gradation is equal to or greater than the first threshold (or the number of pixels exceeding the first threshold) is equal to or less than a predetermined first upper limit (step S14). Alternatively, the first upper limit determination unit 54 may determine whether the number of pixels in the determination target area A whose gradation is equal to or greater than the first threshold (or the number of pixels exceeding the first threshold) is less than a predetermined first upper limit. The first upper limit determination unit 54 determines whether there is a large area on the surface of the balloon 101 where the coating layer 102 contains too much material. If the determination is negative, the first upper limit determination unit 54 determines that there is a large area on the surface of the balloon 101 where the coating layer 102 contains too much material, and determines the grayscale image to be unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing. Examples of cases where there is a large area on the surface of the balloon 101 where the coating layer 102 has too much material include cases where, as shown in FIG. 4(D), crystal clumps 103 are present over a large area of ​​the coating layer 102, cases where an unintended crystal form is present in the coating layer 102, and cases where there are many irregularities on the surface of the coating layer 102. If the first upper limit judgment unit 54 judges in the affirmative, it determines that there is no large area on the surface of the balloon 101 where the coating layer 102 has too much material, and leaves the grayscale image as a candidate for passing. Therefore, the first upper limit specified value is determined by experiment or the like so that the above-mentioned first upper limit judgment unit 54 can make the judgment.

[0045] If the first upper limit judgment unit 54 judges affirmatively, the processing unit 42 causes the gradation difference judgment unit 55 to judge whether the number of pixels in the judgment target area A whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold (or the number of pixels exceeding the gradation difference threshold) is equal to or less than a predetermined gradation difference specified value (step S16). Note that the gradation difference judgment unit 55 may also judge whether the number of pixels in the judgment target area A whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold (or the number of pixels exceeding the gradation difference threshold) is less than the predetermined gradation difference specified value. Each pixel in the judgment target area A other than the outer edge has four adjacent pixels vertically and horizontally. Note that each pixel in the outer edge of the judgment target area A has three or two adjacent pixels vertically and horizontally. The gradation difference of each pixel with its adjacent pixels can be defined as the difference between the pixels whose gradations are most different when the gradation of each pixel is compared with the gradations of all adjacent pixels. For example, in the case of nine pixels Pi (i = 1 to 9) as shown in FIG. 5, pixel P5 is adjacent to four pixels: vertically adjacent pixels P2 and P8, and horizontally adjacent pixels P4 and P6. Each pixel Pi (i = 1 to 9) has a gray level Ti (i = 1 to 9). The gray level difference between pixel P5 and its adjacent pixels can be defined as the maximum value among |T5-T2|, |T5-T4|, |T5-T6|, and |T5-T8|. Alternatively, pixel P5 can be defined as having eight adjacent pixels (P1 to P4, P6 to P9) vertically, horizontally, and diagonally. In this case, the gray level difference between pixel P5 and its adjacent pixels can be defined as the maximum value among |T5-T1|, |T5-T2|, |T5-T3|, |T5-T4|, |T5-T6|, |T5-T7|, and |T5-T8|.

[0046] The gradation difference determination unit 55 determines whether there are few regions where the shading of the material of the coating layer 102 on the surface of the balloon 101 varies. If the determination is negative, the gradation difference determination unit 55 determines that there are wide regions where the shading of the material of the coating layer 102 on the surface of the balloon 101 varies, and determines that the shading image is unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the results on the display device 70 (step S22), and ends the processing. Examples of wide regions where the shading of the material of the coating layer 102 on the surface of the balloon 101 varies include, as shown in FIG. 4(D), the presence of crystal clumps 103 over a wide area of ​​the coating layer 102, the presence of an unintended crystal form in the coating layer 102, and the presence of many irregularities on the surface of the coating layer 102, similar to the above-described case where the first upper limit determination unit 54 determines that there are wide regions where the material of the coating layer 102 on the surface of the balloon 101 is too much. If the judgment is affirmative, the first upper limit judgment unit 54 determines that there are few areas where the material of the coating layer 102 on the surface of the balloon 101 is too much, and so leaves the grayscale image as a candidate for passing. Therefore, the gradation difference specified value is determined by experiment or the like so that the gradation difference judgment unit 55 can make a judgment.

[0047] If the gradation difference determination unit 55 determines that the grayscale difference is not greater than the third threshold, the processing unit 42 determines whether the number of pixels in the determination target area A whose gradation is not greater than the third threshold (or the number of pixels whose gradation is less than the third threshold) is not greater than a predetermined third upper limit (step S17). Alternatively, the third upper limit determination unit 56 may determine whether the number of pixels in the determination target area A whose gradation is not greater than the third threshold (or the number of pixels whose gradation is less than the third threshold) is less than a predetermined third upper limit. The third upper limit determination unit 56 determines whether the area where the coating layer 102 on the surface of the balloon 101 contains too little material is narrow. If the determination is not greater than the third upper limit determination unit 56 determines that the area where the coating layer 102 on the surface of the balloon 101 contains too little material is wide, and determines the grayscale image to be unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing. Examples of cases where there is a large area of ​​too little material in the coating layer 102 on the surface of the balloon 101 include cases where there is a large area of ​​material loss 104 in the coating layer 102, as shown in Figure 4(E), or cases where there is a large foreign object in the coating layer 102. If the judgment is positive, the third upper limit judgment unit 56 determines that the area of ​​too little material in the coating layer 102 on the surface of the balloon 101 is small, as shown in Figure 4(F), and judges the grayscale image to be acceptable (step S18). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing.

[0048] If the first gradation judgment unit 53 judges negative, the processing unit 42 determines, via the second gradation judgment unit 57, whether the gradation average value is equal to or greater than a predetermined second threshold (step S19). Alternatively, the second gradation judgment unit 57 may judge whether the gradation average value exceeds a predetermined second threshold. The second threshold is a value greater than 0 and less than 255. The second threshold is smaller than the first threshold. The second threshold is determined through experiments or the like as a threshold for determining whether the amount of material in the coating layer 102 on the surface of the balloon 101 is less than when the first gradation judgment unit 53 judges positive, but is equal to or greater than a desired predetermined amount overall. If the judgment is positive, the second gradation judgment unit 57 determines that the gradation is relatively white and that the amount of material in the coating layer 102 is equal to or greater than a predetermined amount overall, although not as much as when the first gradation judgment unit 53 judges positive, and so retains the gradation image as a candidate for passing. If the determination is negative, the second shading determination unit 57 determines that the amount of material in the coating layer 102 as a whole is less than the predetermined amount, and determines the shading image to be unacceptable (step S15). As shown in FIG. 4(B), if an exposed portion 105 is present on the surface of the balloon 101 and no crystal mass 103 is present, the determination is negative in step S19, and the shading image is determined to be unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing.

[0049] If the second grayscale determination unit 57 determines that the number of pixels in the determination target area A whose grayscale is equal to or greater than the second threshold (or the number of pixels exceeding the second threshold) is equal to or less than a predetermined second upper limit (step S20). Alternatively, the second upper limit determination unit 58 may determine that the number of pixels in the determination target area A whose grayscale is equal to or greater than the second threshold (or the number of pixels exceeding the second threshold) is less than a predetermined second upper limit. The second upper limit determination unit 58 determines whether there is a large area on the surface of the balloon 101 where the material of the coating layer 102 is too much. If the determination is negative, the second upper limit determination unit 58 determines that there is a large area on the surface of the balloon 101 where the material of the coating layer 102 is too much, and judges the grayscale image (step S15). As shown in FIG. 4(C), if the exposed portion 105 and the crystal mass 103 are present on the surface of the balloon 101, the determination in step S20 is negative, and the grayscale image is determined to be unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the process. If the determination is positive, the second upper limit determination unit 58 determines that there is not a large area on the surface of the balloon 101 where the coating layer 102 has too much material, and leaves the grayscale image as a candidate for acceptance. Therefore, the second upper limit specified value is determined by experiment or the like so that the above-mentioned second upper limit determination unit 58 can make a determination. The second upper limit specified value is different from the first upper limit specified value, but they may also be the same.

[0050] The determination in the second upper limit determination unit 58 (step S20) differs from the determination in the first upper limit determination unit 54 (step S14) that uses the first upper limit specified value only in that the second upper limit determination unit 58 uses the second upper limit specified value.

[0051] If the second upper limit determination unit 58 determines that the second upper limit is not greater than the fourth threshold, the processing unit 42 determines whether the number of pixels in the determination target area A whose gradation is equal to or less than the fourth threshold (or the number of pixels whose gradation is less than the fourth threshold) is equal to or less than a predetermined fourth upper limit (step S21). Alternatively, the fourth upper limit determination unit 59 may determine whether the number of pixels in the determination target area A whose gradation is equal to or less than the fourth threshold (or the number of pixels whose gradation is less than the fourth threshold) is less than a predetermined fourth upper limit. The fourth upper limit determination unit 59 determines whether the area where the coating layer 102 on the surface of the balloon 101 contains too little material is narrow. If the fourth upper limit determination unit 59 determines that the balloon 101 contains too little material in the coating layer 102 on the surface of the balloon 101 contains too little material, and determines the grayscale image to be unacceptable (step S15). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing. If the determination is affirmative, the fourth upper limit determination unit 59 determines that the area where the material of the coating layer 102 on the surface of the balloon 101 is too small is narrow, and determines the grayscale image as pass (step S18). Next, the processing unit 42 causes the result output unit 60 to display the result on the display device 70 (step S22), and ends the processing. Therefore, the fourth upper limit specified value is determined by experiment or the like so that the above-mentioned fourth upper limit determination unit 59 can make a determination.

[0052] The judgment by the fourth upper limit judgment unit 59 (step S21) is the same as the judgment by the third upper limit judgment unit 56 (step S17), but the specified values ​​of the fourth upper limit judgment unit 59 and the third upper limit judgment unit 36 ​​may be the same or different.

[0053] Furthermore, the determination by the tone difference determination unit 55 (step S17) may be made between the determination by the second upper limit determination unit 58 (step S20) and the determination by the fourth upper limit determination unit 59 (step S21).

[0054] Steps S14, S16, and S17 performed after the first shading judgment unit 53 makes a positive judgment (step S13) are performed when the white color in the shading image is deep and there is a large amount of material in the coating layer 102. In contrast, steps S20 and S21 performed after the second shading judgment unit 57 makes a positive judgment (step S19) are performed when the white color in the shading image is light and there is a small amount of material in the coating layer 102. In this way, appropriate specified values ​​(first upper limit specified value, tone difference specified value, third upper limit specified value, second upper limit specified value) can be selected and used depending on the difference in the shading of the white color in the shading image, i.e., depending on the amount of material in the coating layer 102. In this embodiment, the pass / fail judgment of the grayscale image is performed for two patterns: when the judgment by the first grayscale judgment unit 53 using the first threshold (average gradation value ≧ first threshold) is positive, and when the judgment by the second grayscale judgment unit 57 using the second threshold (average gradation value ≧ second threshold). However, the threshold may be gradually decreased to prepare further thresholds (third threshold, fourth threshold, fifth threshold, . . . , Nth threshold), and appropriate specified values ​​(upper limit specified value, specified gradation difference value) may be set according to the coating layer 102 of the average gradation value that satisfies each threshold. Then, for each threshold pattern, a judgment step using the upper limit specified value as in step S14 or step S20, a judgment step using the specified gradation difference value as in step S16, and a judgment step using the upper limit specified value as in step S17 or step S21 may be performed to judge the pass / fail of the grayscale image. The number N of thresholds to be gradually decreased is not particularly limited.

[0055] As described above, the coating layer inspection device 10 according to this embodiment is a coating layer inspection device 10 that inspects the coating layer 102 formed on the surface of an object to be inspected, and includes an imaging unit 30 that images the coating layer 102 and creates image data, and a processing unit 42 that performs image processing. The processing unit 42 includes a digitizing unit 50 that grayscales the image data to create a grayscale image and digitizes the gradation information of each pixel so that it increases from black to white, an area specifying unit 51 that specifies a determination target area A where the coating layer 102 of the object to be inspected is formed, and an average gradation value of all pixels present in the determination target area A. a first gradation judgment unit 53 that judges whether the gradation average value is equal to or greater than a predetermined first threshold value or whether it exceeds the first threshold value, and if the judgment is positive, leaves the gradation image as a candidate for passing; and a first upper limit judgment unit 54 that judges whether the number of pixels whose gradation is equal to or greater than the first threshold value in the judgment target area A is equal to or less than a predetermined first upper limit value or whether it is less than the first upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image as a reject.

[0056] The coating layer inspection device 10 configured as described above selects, by the first shade determination unit 53, an inspection object that is determined to have a strong white color and therefore to have more than a predetermined amount of coating layer 102 material that can be passed, and can exclude, by the first upper limit determination unit 54, inspection objects that have large areas with too much coating layer 102 material. Therefore, the coating layer inspection method determines the defectivity of the coating layer 102 of an inspection object based on multiple determinations, and can therefore determine the defectivity of the coating layer 102 of the inspection object with high accuracy.

[0057] The coating layer inspection device 10 has a third upper limit judgment unit 56 that judges whether the number of pixels in the judgment target area A whose gradation is equal to or less than the third threshold value is equal to or less than a predetermined third upper limit value, and if the judgment is positive, keeps the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image to be unacceptable. The third upper limit judgment unit 56 enables the coating layer inspection device 10 to exclude inspection objects in which there are large areas where the material of the coating layer 102 is too little. Therefore, the coating layer inspection device 10 judges the defectivity of the coating layer 102 based on multiple judgments, thereby enabling the defectivity of the coating layer 102 of the inspection object to be judged with even greater accuracy.

[0058] The coating layer inspection device 10 has a second grayscale judgment unit 57 that, when the first grayscale judgment unit 53 makes a negative judgment, judges whether the average grayscale value is equal to or greater than a predetermined second threshold value that is smaller than the first threshold value, and whether the grayscale image is deemed acceptable if the judgment is positive, and a second upper limit judgment unit 58 that judges whether the number of pixels whose grayscale is equal to or greater than the second threshold value in the judgment target area A is equal to or less than a predetermined second upper limit value, and whether the number of pixels whose grayscale is equal to or greater than the second threshold value is equal to or less than a predetermined second upper limit value, and whether the grayscale image is deemed acceptable if the judgment is positive, and whether the grayscale image is deemed acceptable if the judgment is negative. This allows the inspection device to select, by the second grayscale judgment unit 57, inspected objects that have a weak white color but are deemed to have at least a predetermined amount of coating layer 102 material that can be accepted, and to exclude, by the second upper limit judgment unit 58, inspected objects that have large areas with too much coating layer 102 material. Therefore, this inspection device can use desirable thresholds and specified values ​​according to the average gradation value to accurately exclude quality that should be judged as unacceptable, and can prevent specimens that should be judged as good from being judged as unacceptable.

[0059] The coating layer inspection device 10 has a fourth upper limit judgment unit 59 that judges whether the number of pixels in the judgment target area A whose gradation is equal to or less than a predetermined fourth threshold value or less than the fourth threshold value is equal to or less than a predetermined fourth upper limit value, and if the judgment is positive, keeps the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image as failing. This allows the coating layer inspection device 10, using the fourth upper limit judgment unit 59, to exclude inspection objects with large areas where the material of the coating layer 102 is too little. Therefore, the coating layer inspection device 10 uses a desirable threshold value and a predetermined value according to the average gradation value to accurately exclude quality that should be judged as failing, and can prevent inspection objects that should be judged as good from being judged as failing.

[0060] The coating layer inspection device 10 has a gradation difference judgment unit 55 that judges whether the number of pixels in the judgment target area A whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold, or whether the number of pixels that exceed the gradation difference threshold, is equal to or less than a predetermined gradation difference specified value, and if the judgment is positive, leaves the grayscale image as a candidate for passing, and if the judgment is negative, judges the grayscale image to be unacceptable. This allows the inspection device to exclude specimens in which the gradation difference judgment unit 55 judges that the coating layer 102 has large local changes. This allows the inspection device to more accurately judge the defects of the coating layer 102 of the specimen.

[0061] The specimen is a balloon 101 that can be inserted into a biological lumen, and the coating layer 102 contains a drug. This allows the inspection device to determine with high accuracy whether the coating layer 102 on the surface of the balloon 101 is defective.

[0062] The coating layer inspection method of this embodiment is a coating layer inspection method for inspecting a coating layer 102 formed on the surface of an object, and includes the steps of: capturing an image of the coating layer 102 to obtain image data; gray-scaling the image data to obtain a grayscale image; and quantifying the gradation information of each pixel so that it increases from black to white in step S10; specifying a determination target area A where the coating layer 102 of the object is formed; calculating an average gradation value of all pixels present in the determination target area A; and calculating a value of the average gradation value. The method includes a first gradation judgment step S13 in which the number of pixels whose gradation is equal to or greater than a predetermined first threshold value or exceeds the first threshold value is judged to be positive, and if the judgment is positive, the gradation image is left as a candidate for passing, and a first upper limit judgment step S14 in which the number of pixels whose gradation is equal to or greater than the first threshold value or the number of pixels whose gradation is greater than or equal to a predetermined first upper limit value is judged to be less than the first upper limit value or is less than the first upper limit value, and if the judgment is positive, the gradation image is left as a candidate for passing, and if the judgment is negative, the gradation image is judged as a failure.

[0063] The coating layer inspection method configured as described above selects, in the first density determination step S13, an inspection object that is determined to have a strong white color and therefore to have more than a predetermined amount of coating layer 102 material that can be passed, and in the first upper limit determination step S14, can exclude inspection objects that have large areas with too much coating layer 102 material. Therefore, this coating layer inspection method determines the defectivity of the coating layer 102 through multiple determination steps, and can therefore determine the defectivity of the coating layer 102 of the inspection object with high accuracy.

[0064] The coating layer inspection method also includes a third upper limit determination step S17 in which it is determined whether the number of pixels in the determination target area A whose gradation is equal to or less than a predetermined third threshold value is equal to or less than a predetermined third upper limit value, and if the determination is affirmative, the grayscale image is retained as a candidate for passing, and if the determination is negative, the grayscale image is determined to be unacceptable. This allows the coating layer inspection method to exclude, by the third upper limit determination step S17, specimens in which there are large areas where the material of the coating layer 102 is too little. Therefore, this coating layer inspection method determines the defectivity of the coating layer 102 of the specimen through multiple determination steps, thereby enabling highly accurate determination of the defectivity of the coating layer 102 of the specimen. Note that either the first upper limit determination step S14 or the third upper limit determination step S17 may be performed first.

[0065] The coating layer inspection method may further include a second grayscale judgment step S19 for judging whether the average grayscale value is equal to or greater than a predetermined second threshold value that is smaller than the first threshold value if the judgment is negative in the first grayscale judgment step S13, retaining the grayscale image as a candidate for passing if the judgment is positive, and judging the grayscale image as a failure if the judgment is negative, and a second upper limit judgment step S20 for judging whether the number of pixels whose grayscale is equal to or greater than the second threshold value in the judgment target area A is equal to or less than a predetermined second upper limit value, retaining the grayscale image as a candidate for passing if the judgment is positive, and judging the grayscale image as a failure if the judgment is negative. This allows the second grayscale judgment step to select inspected objects that are weakly white but are judged to have at least a predetermined amount of coating layer 102 material that can be passed, and the second upper limit judgment step to exclude inspected objects with large areas where the coating layer 102 material is too much. Therefore, this inspection method can use desirable thresholds and specified values ​​according to the average gradation value to accurately exclude quality that should be judged as unacceptable, and can prevent specimens that should be judged as good from being judged as unacceptable.

[0066] The coating layer inspection method may also include a fourth upper limit determination step S21 in which the number of pixels in the determination target area A whose gradation is equal to or less than a predetermined fourth threshold or less than the fourth threshold is equal to or less than a predetermined fourth upper limit, and if the determination is affirmative, the grayscale image is retained as a candidate for passing, and if the determination is negative, the grayscale image is determined to be unacceptable. This allows the fourth upper limit determination step S21 to exclude inspection objects with large areas where the coating layer 102 material is too thin. Therefore, the inspection method uses a desirable fourth upper limit value according to the average gradation value to accurately exclude quality that should be determined to be unacceptable, and can prevent inspection objects that should be determined to be non-defective from being determined to be unacceptable.

[0067] The coating layer inspection method may include a gradation difference determination step S16, at any point after the first gradation determination step S13, in which the number of pixels in the determination target area A whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold or the number of pixels whose gradation difference exceeds the gradation difference threshold is equal to or less than a predetermined gradation difference specified value, and if the determination is positive, the gradation image is left as a candidate for passing, and if the determination is negative, the gradation image is determined to be unacceptable. This allows the inspection method to exclude specimens in which the coating layer 102 is determined to have large local changes in the gradation difference determination step S16. This allows the inspection method to more accurately determine the defectivity of the coating layer 102 of the specimen.

[0068] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. For example, the specimen inspected by the coating layer inspection device 10 is not limited to the balloon 101. The specimen may be, for example, a medical device such as the balloon 101, a stent, a catheter, a guidewire, or an endoscope, or a non-medical device. The coating layer provided on the specimen may be, for example, a layer formed of a drug, a layer formed of a low-friction material (e.g., a fluororesin) for improving abrasion resistance, a layer formed of a hydrophilic polymer, or a layer formed of a polymer for preventing thrombus adhesion. More specifically, the specimen may be, for example, a catheter having a hydrophilic coating as a coating layer, a guidewire having a polymer coating for preventing thrombus adhesion as a coating layer, or a guidewire or endoscope having a PTFE coating or PEEK coating for improving abrasion resistance.

[0069] Even if the coating layer 102 is transparent, the above-described inspection may be possible by devising the illumination of the coating layer 102 by the illumination device 20 or by preprocessing the coating layer 102 or the captured image. For example, when the surface of the coating layer 102 is uneven, the illumination may be devised by irradiating the coating layer 102 with light from a direction intersecting (e.g., perpendicular to) the imaging direction of the imaging unit 30. This allows shadows of different sizes and patterns depending on the shape of the coating layer 102 to be captured in the grayscale image, making it possible to carry out the inspection method using the grayscale image described above. Furthermore, the number of illumination sources does not need to be one. By irradiating the coating layer 102 from multiple illumination sources from different directions, shadows of different sizes and patterns depending on the shape of the coating layer 102 can be captured in the grayscale image, making it possible to carry out the inspection method using the grayscale image described above. When multiple illumination sources are used, the types of illumination sources may be the same or different. Pre-processing includes destructive means such as applying a coloring process to the coating layer 102 to visualize the differences in shading of the transparent coating layer 102, and non-destructive means such as applying binarization, contrast adjustment, noise control, etc. to the captured image to visualize the differences in shading. [Explanation of symbols]

[0070] 10 Coating layer inspection device 20 Lighting equipment 30 Imaging unit 40 Processing equipment 41 Interface 42 Processing section 50 Digitization Department 51 Area identification part 52 Gradation average calculation section 53 1st density judgment section 54 1st Upper Limit Judgment Section 55 Gradation difference judgment unit 56 3rd Upper Limit Judgment Section 57 2nd density judgment section 58 2nd Upper Limit Judgment Section 59 4th Upper Limit Judgment Section 101 Balloon (Subject) 102 Coat layer A. Judgment area

Claims

1. A coating layer inspection device for inspecting a coating layer formed on a surface of an object, comprising: an imaging unit that images the coating layer and creates image data; a processing unit that performs image processing, The processing unit includes a digitizing unit that converts the image data into a grayscale image and converts the gradation information of each pixel into a digital value that increases from black to white; a region specifying unit for specifying a determination target region of the test object where the coating layer is to be formed; a gradation average value calculation unit that calculates an average gradation value of all pixels present in the determination target area; a first gradation determination unit that determines whether the average gradation value is equal to or greater than a predetermined first threshold value, and if the determination is affirmative, leaves the grayscale image as a candidate for passing; a first upper limit judgment unit that judges whether the number of pixels in the judgment target area whose gradation is equal to or greater than the first threshold value or the number of pixels whose gradation exceeds the first threshold value is equal to or less than a predetermined first upper limit value or whether it is less than the first upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

2. The coating layer inspection device of claim 1, further comprising a third upper limit judgment unit that judges whether the number of pixels within the judgment target area whose gradation is equal to or less than a predetermined third threshold value or the number of pixels whose gradation is less than the third threshold value is equal to or less than a predetermined third upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

3. a second shading judgment unit that, when the first shading judgment unit makes a negative judgment, judges whether the average gradation value is equal to or greater than a second threshold value that is smaller than the first threshold value, or whether it exceeds the second threshold value, and when the judgment is positive, leaves the shading image as a candidate for passing, and when the judgment is negative, judges the shading image to be unacceptable; 3. The coating layer inspection device according to claim 1, further comprising: a second upper limit judgment unit that judges whether the number of pixels in the judgment target area whose gradation is equal to or greater than the second threshold value or the number of pixels whose gradation exceeds the second threshold value is equal to or less than a predetermined second upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

4. The coating layer inspection device of claim 3 has a fourth upper limit judgment unit that judges whether the number of pixels within the judgment target area whose gradation is below a predetermined fourth threshold value or the number of pixels whose gradation is less than the fourth threshold value is below a predetermined fourth upper limit value or whether it is less than the fourth upper limit value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

5. The coating layer inspection device according to any one of claims 1 to 4, further comprising a gradation difference judgment unit that judges whether the number of pixels in the judgment target area whose gradation difference with adjacent pixels is equal to or greater than a predetermined gradation difference threshold, or whether the number of pixels whose gradation difference exceeds the gradation difference threshold, is equal to or less than a predetermined gradation difference specified value, or whether it is less than the gradation difference specified value, and if the judgment is positive, leaves the gradation image as a candidate for passing, and if the judgment is negative, judges the gradation image to be unacceptable.

6. 6. The coating layer inspection device according to claim 1, wherein the specimen is a balloon that can be inserted into a body lumen, and the coating layer contains a drug.

7. A coating layer inspection method for inspecting a coating layer formed on a surface of an object, comprising: imaging the coating layer to obtain image data; A step of gray-scaling the image data to form a grayscale image and converting the gradation information of each pixel into a numerical value that increases from black to white; identifying a determination target region of the test object where the coating layer is to be formed; calculating an average gradation value of all pixels present in the determination target area; a first gradation determination step of determining whether the average gradation value is equal to or greater than a predetermined first threshold value or exceeds the first threshold value, and if the determination is affirmative, leaving the grayscale image as a candidate for passing; a first upper limit judgment step of judging whether the number of pixels in the judgment target area whose gradation is equal to or greater than the first threshold value or the number of pixels whose gradation exceeds the first threshold value is equal to or less than a predetermined first upper limit value or whether it is less than the first upper limit value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and if the judgment is negative, judging the gradation image to be unacceptable.

8. The coating layer inspection method of claim 7, further comprising a third upper limit judgment step of judging whether the number of pixels within the judgment target area whose gradation is equal to or less than a predetermined third threshold value or the number of pixels whose gradation is less than the third threshold value is equal to or less than a predetermined third upper limit value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and if the judgment is negative, judging the gradation image to be unacceptable.

9. a second gradation judgment step in which, if the judgment in the first gradation judgment step is negative, the gradation average value is judged to be equal to or greater than a second threshold value that is predetermined and smaller than the first threshold value, or whether it exceeds the second threshold value, and if the judgment is positive, the gradation image is left as a candidate for passing, and if the judgment is negative, the gradation image is judged to be unacceptable; 9. The coating layer inspection method according to claim 7 or 8, further comprising a second upper limit judgment step of judging whether the number of pixels in the judgment target area whose gradation is equal to or greater than the second threshold value or the number of pixels whose gradation exceeds the second threshold value is equal to or less than a predetermined second upper limit value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and if the judgment is negative, judging the gradation image to be unacceptable.

10. 10. The coating layer inspection method of claim 9, further comprising a fourth upper limit judgment step of judging whether the number of pixels within the judgment target area whose gradation is equal to or less than a predetermined fourth threshold value or the number of pixels whose gradation is less than the fourth threshold value is equal to or less than a predetermined fourth upper limit value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and if the judgment is negative, judging the gradation image to be unacceptable.

11. 11. The coating layer inspection method according to claim 7, further comprising a gradation difference judgment step, at any point after the first gradation judgment step, of judging whether the number of pixels whose gradation difference with adjacent pixels in the judgment target area is equal to or greater than a predetermined gradation difference threshold, or the number of pixels whose gradation difference exceeds the gradation difference threshold, is equal to or less than a predetermined gradation difference specified value, or whether it is less than the gradation difference specified value, and if the judgment is positive, leaving the gradation image as a candidate for passing, and if the judgment is negative, judging the gradation image to be unacceptable.

12. 12. The coating layer inspection method according to claim 7, wherein the specimen is a balloon that can be inserted into a body lumen, and the coating layer contains a drug.

Images