Protective glass monitoring system and method

Abstract

A protective glass monitoring system and method according to various embodiments of the present invention can predict the replacement timing for protective glass of a laser welding device through real-time monitoring of the protective glass, and can minimize unnecessary replacement of the protective glass by increasing the reliability of determination of a contamination level of the protective glass.

Description

Protective glass monitoring system and method

[0001] The present invention relates to a protective glass monitoring system and method capable of predicting the replacement time of the protective glass by monitoring the protective glass of a laser welding machine in real time.

[0002] A laser welding machine is a device that processes an object, such as metal, by welding, marking, cutting, etc., by irradiating it with a laser. Such a laser welding machine includes a lens that focuses the emitted laser and a protective glass that can protect the lens from foreign matter that flies up from the object during laser welding.

[0003] During laser welding, the metal evaporates due to the high-density, high-power laser, generating vapor pressure. Due to this vapor pressure, some particles of the molten metal detach from the weld area and fuse or condense, causing specters or fumes to be generated.

[0004] Spatter or fumes cause contamination of the protective glass, and when the laser passes through the contaminated area, it results in a decrease in laser intensity and scattering. In this case, welding defects occur where the welded part of the object easily detaches. Therefore, the protective glass is the component that consumes the most power in a laser welding machine and requires real-time management.

[0005] Generally, workers visually inspect the degree of contamination of the protective glass and replace it. However, since this management method inevitably takes action only after welding defects occur, it has a negative impact on the equipment utilization rate, which is a key indicator of the production process.

[0006] In addition, if replacement is decided based on the worker's visual inspection of the degree of contamination at the production site, the process is carried out based on the worker's qualitative judgment. Since lasers pass through only a portion of the total surface area of ​​the protective glass, welding defects occur only when this area becomes contaminated.

[0007] However, in the production field, workers cannot visually determine which parts of the protective glass the laser is penetrating. Consequently, the degree of contamination of the protective glass cannot be quantitatively assessed, which may lead to unnecessary replacement of the protective glass. Furthermore, the replacement of unnecessary consumables has a negative impact on the unit cost of the product.

[0008] The present invention relates to a protective glass monitoring system and method, and more specifically, aims to provide a protective glass monitoring system and method capable of predicting the replacement time of the protective glass by monitoring the protective glass of a laser welding machine in real time.

[0009] In addition, the purpose is to provide a protective glass monitoring system and method that can minimize unnecessary replacement of protective glass by increasing the reliability of determining the contamination level of the protective glass.

[0010] The problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0011] A protective glass monitoring system for a laser welding machine comprises: a camera module mounted on the laser welding machine to capture an image of the protective glass; a communication module that transmits and receives coordinate data for a welding line through which a laser passes through the protective glass; a detection module that matches the captured image with the coordinate data to acquire a monitoring image including the welding line and detects foreign substances in the acquired monitoring image; a judgment module that calculates a contamination level by applying a weight based on the distance between the detected foreign substances and the welding line, and determines whether the protective glass is abnormal based on whether the calculated contamination level satisfies a preset standard contamination level; and an output module that outputs information regarding whether the protective glass is abnormal based on the determination.

[0012] The detection module can subdivide the acquired monitoring image into pixel units and detect foreign substances for each subdivided pixel unit.

[0013] The above judgment module can calculate the contamination level for each of the subdivided pixel units.

[0014] The above weight is higher as the distance between the detected foreign substance and the welding line is closer, and the judgment module can determine that the protective glass is defective if the calculated contamination level exceeds a preset standard contamination level.

[0015] The above judgment module can calculate the transparency of the area where no foreign substance is detected in the acquired monitoring image, and determine whether there is an abnormality in the protective glass based on whether the calculated transparency satisfies a preset standard transparency.

[0016] The above judgment module may determine that the protective glass is defective if the calculated contamination level does not satisfy a preset standard contamination level or if the calculated transparency level does not satisfy a preset standard transparency level.

[0017] The detection module subdivides the acquired monitoring image into pixel units and detects foreign substances for each subdivided pixel unit, and the judgment module can calculate transparency for each pixel unit in which no foreign substances are detected in the subdivided pixel unit.

[0018] The laser welding device may include: a main body that emits a laser; a plurality of mirrors arranged so that the emitted laser is reflected and passes through the protective glass; and a welding camera that acquires coordinate data for the welding line and transmits it to the communication module.

[0019] The camera module may include a CCD camera configured to capture an image of the protective glass through the plurality of mirrors.

[0020] A method for monitoring a protective glass of a laser welding machine comprises the steps of: capturing an image of the protective glass through a camera module mounted on the laser welding machine; transmitting and receiving coordinate data for a welding line through which a laser passes through the protective glass; matching the captured image with the coordinate data to obtain a monitoring image including the welding line; detecting foreign substances in the obtained monitoring image; calculating a contamination level by applying a weight based on the distance between the detected foreign substances and the welding line; determining whether the protective glass is abnormal based on whether the calculated contamination level satisfies a preset standard contamination level; and outputting information regarding whether the protective glass is abnormal based on the determination.

[0021] The step of detecting foreign substances above can subdivide the acquired monitoring image into pixel units and detect foreign substances for each subdivided pixel unit.

[0022] The step of calculating the contamination level above can calculate the contamination level for each of the subdivided pixel units.

[0023] The above weighting is higher as the distance between the detected foreign substance and the welding line becomes shorter, and the step of determining whether the protective glass is defective may determine that the protective glass is defective if the calculated contamination level exceeds a preset standard contamination level.

[0024] The method further includes a step of calculating transparency for an area where no foreign substances are detected in the above-acquired monitoring image, and the step of determining whether there is an abnormality in the protective glass can determine whether there is an abnormality in the protective glass based on whether the calculated transparency satisfies a preset standard transparency.

[0025] The step of determining whether there is a defect in the protective glass may determine that the protective glass is defective if the calculated contamination level does not satisfy a preset standard contamination level or if the calculated transparency level does not satisfy a preset standard transparency level.

[0026] The protective glass monitoring system and method according to the present invention can predict the replacement time of the protective glass by monitoring the protective glass of a laser welding machine in real time.

[0027] In addition, the reliability of determining the contamination level of the protective glass can be increased, thereby minimizing unnecessary replacement of the protective glass.

[0028] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below.

[0029] FIG. 1 is a block diagram of a protective glass monitoring system according to one embodiment of the present invention.

[0030] FIG. 2 is a drawing showing a camera module mounted on a laser welding machine in a protective glass monitoring system according to one embodiment of the present invention.

[0031] FIGS. 3 to 5 are drawings for explaining the features of acquiring a monitoring image in a protective glass monitoring system according to an embodiment of the present invention.

[0032] FIG. 6 is a diagram illustrating the features of calculating the contamination level in a protective glass monitoring system according to one embodiment of the present invention.

[0033] FIG. 7 is a diagram illustrating the feature of subdividing a monitoring image into pixel units in a protective glass monitoring system according to one embodiment of the present invention.

[0034] FIG. 8 is a drawing illustrating a protective glass monitoring method according to an embodiment of the present invention.

[0035] FIG. 9 is a drawing for illustrating another embodiment of the protective glass monitoring method of the present invention.

[0036] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols will be assigned the same reference number, and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not inherently possess distinct meanings or roles. Furthermore, in describing embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description will be omitted. Additionally, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification; the technical concept disclosed in this specification is not limited by the attached drawings, and it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0037] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0038] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0039] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0040] In this application, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0041] FIG. 1 is a block diagram of a protective glass monitoring system (100) according to an embodiment of the present invention. FIG. 2 is a diagram showing a camera module (120) mounted on a laser welding machine (110) in a protective glass monitoring system (100) according to an embodiment of the present invention. FIG. 3 to 5 are diagrams for explaining the feature of acquiring a monitoring image (141) in a protective glass monitoring system (100) according to an embodiment of the present invention. FIG. 6 is a diagram for explaining the feature of calculating a contamination level in a protective glass monitoring system (100) according to an embodiment of the present invention. FIG. 7 is a diagram for explaining the feature of subdividing the monitoring image (141) into pixel units (142) in a protective glass monitoring system (100) according to an embodiment of the present invention.

[0042] Referring to FIG. 1 and FIG. 2 together, a protective glass monitoring system (100) according to one embodiment of the present invention can monitor a protective glass (111) of a laser welding device (110) in real time and may include a camera module (120), a communication module (130), a detection module (140), a judgment module (150), and an output module (160).

[0043] Here, the laser welding device (110) may include a main body (112) that emits a laser for welding an object (10), a lens (114) for focusing the emitted laser, and a protective glass (111) attached to the lens (114). It may also include a plurality of mirrors (113) arranged so that the emitted laser is reflected and passes through the protective glass (111).

[0044] Additionally, the laser welding device (110) may include a welding camera (114) that acquires coordinate data for a welding line (L) to be described later and transmits it to a communication module (130). The welding camera (114) may be configured and positioned to follow the path of a laser reflected through a plurality of mirrors (113).

[0045] A camera module (120) is mounted on a laser welding machine (110) and can serve to capture an image (121) of a protective glass (111) as shown in FIG. 4. Here, the camera module (120) can be mounted on the laser welding machine (110) so as to follow the path of a laser reflected through a plurality of mirrors (113). Accordingly, the camera module (120) may include a CCD camera configured to capture an image (121) of the protective glass (111).

[0046] Referring together to FIGS. 3 to 5, in a protective glass monitoring system (100) according to one embodiment of the present invention, a communication module (130) can transmit and receive coordinate data for a welding line (L) through which a laser passes through a protective glass (111). FIG. 3 is a drawing illustrating the shape of a laser passing through a protective glass (111), and coordinate data of the welding line (L) can be obtained through the welding camera (114) described above based on the center point (C) of the transmitted laser.

[0047] In addition, in a protective glass monitoring system (100) according to one embodiment of the present invention, the detection module (140) can match coordinate data with a captured image (121) to obtain a monitoring image (141) including a welding line (L), and can detect foreign substances in the obtained monitoring image (141). FIG. 4 is a diagram showing an image obtained by matching coordinate data with a monitoring image (141) obtained through a camera module (120). FIG. 5 is a diagram showing a monitoring image (141) including a welding line (L).

[0048] This is to obtain a monitoring image (141) including the welding line (L) through the detection module (140) and to detect foreign substances in the obtained monitoring image (141), as welding defects occur when there are foreign substances on the welding line (L) as described above.

[0049] And through this, the protective glass monitoring system (100) according to one embodiment of the present invention can detect only foreign substances related to welding defects, thereby improving the detection speed of foreign substances and, accordingly, improving the monitoring efficiency of the protective glass (111).

[0050] In addition, in a protective glass monitoring system (100) according to one embodiment of the present invention, a judgment module (150) can calculate the contamination level by applying a weight based on the distance between the detected foreign substance and the welding line (L), and determine whether there is an abnormality in the protective glass (111) depending on whether the calculated contamination level satisfies a preset standard contamination level.

[0051] Here, the weight is higher as the distance between the detected foreign substance and the welding line (L) becomes closer. And in the protective glass monitoring system (100) according to one embodiment of the present invention, the judgment module (150) can determine that the protective glass (111) is defective if the calculated contamination level exceeds a preset standard contamination level.

[0052] Referring to FIG. 6, foreign substances (20, 30) located on the welding line (L) have a higher weight applied compared to foreign substances (40) located off the welding line (L). Furthermore, among foreign substances (20, 30) located on the welding line (L), different weights may be applied depending on the distance from the center point (C).

[0053] That is, weights may be applied differently depending on the distance (d1, d2, d3) between the foreign substance (20, 30, 40) and the center point (C). Therefore, the highest weight may be applied to the foreign substance (20) with a distance of d1 from the center point (C), and a lower weight may be applied to the foreign substance (30) with a distance of d2 from the center point (C). And the lowest weight may be applied to the foreign substance (40) with a distance of d3 from the center point (C).

[0054] Accordingly, a protective glass monitoring system (100) according to one embodiment of the present invention can apply a weight based on the distance between the detected foreign substance and the welding line (L), and can quantitatively calculate the contamination level through the application of the weight. And through this, the reliability of determining the contamination level of the protective glass (111) can be increased.

[0055] Referring together with FIG. 7, in a protective glass monitoring system (100) according to one embodiment of the present invention, the detection module (140) can subdivide the acquired monitoring image (141) into pixels (142) and detect foreign substances for each subdivided pixel (142) unit. The judgment module (150) can calculate the contamination level for each subdivided pixel (142) unit and can determine whether there is an abnormality in the protective glass (111) based on whether it satisfies a preset standard contamination level as described above.

[0056] By doing so, the protective glass monitoring system (100) according to one embodiment of the present invention can further increase the reliability of determining the contamination level of the protective glass (111) by distinguishing between pixels (142) through which the welding line (L) passes and pixels (142) through which the welding line (L) does not pass in the acquired monitoring image (141), and by detecting foreign substances on a pixel (142) basis and applying weights.

[0057] Furthermore, referring again to FIGS. 3 to 6, in a protective glass monitoring system (100) according to one embodiment of the present invention, a judgment module (150) can calculate the transparency of an area where no foreign substance is detected in an acquired monitoring image (141), and determine whether there is an abnormality in the protective glass (111) based on whether the calculated transparency satisfies a preset standard transparency.

[0058] This is because, even in areas not contaminated by foreign substances, the transmission of the laser may vary depending on the degree of transparency of the protective glass (111), and welding defects may occur as a result.

[0059] Accordingly, in a protective glass monitoring system (100) according to one embodiment of the present invention, the judgment module (150) may determine that the protective glass (111) is defective if the calculated contamination level does not satisfy a preset standard contamination level or if the calculated transparency level does not satisfy a preset standard transparency level.

[0060] In addition, in accordance with the principle described above through FIG. 7, the judgment module (150) in the protective glass monitoring system (100) according to one embodiment of the present invention can calculate transparency for each pixel (142) unit in which no foreign substance is detected at the subdivided pixel (142) unit. And, depending on whether it satisfies a preset standard transparency, it can determine whether there is an abnormality in the protective glass (111). Through this, the reliability of the transparency judgment of the protective glass (111) can be further increased.

[0061] Referring again to FIG. 1, in a protective glass monitoring system (100) according to one embodiment of the present invention, the output module (160) can output information regarding whether there is an abnormality in the protective glass (111) determined through the judgment module (150).

[0062] For example, if the judgment module (150) determines that the protective glass (111) is defective, the output module (160) may display information that the protective glass (111) needs to be replaced or output an alarm. Additionally, if the judgment module (150) determines that the protective glass (111) is not defective, the output module (160) may output information related to this.

[0063] Meanwhile, the block diagram of the protective glass monitoring system (100) illustrated in FIG. 1 is merely a block diagram for one embodiment of the present invention, and each component of the block diagram may be integrated, added, or omitted according to the specifications of the protective glass monitoring system (100) actually implemented.

[0064] That is, as needed, two or more components may be combined into a single component, or a single component may be subdivided into two or more components. In addition, the functions performed in each block are intended to explain embodiments of the present invention, and the specific operations or devices thereof do not limit the scope of the present invention.

[0065] FIG. 8 is a drawing illustrating a protective glass monitoring method according to one embodiment of the present invention. FIG. 9 is a drawing illustrating another embodiment of the protective glass monitoring method of the present invention.

[0066] Hereinafter, the protective glass monitoring method of the present invention will be explained by combining the details described above with reference to FIGS. 1 to 7.

[0067] As illustrated in FIG. 8, a protective glass monitoring method according to one embodiment of the present invention can first capture an image (121) of a protective glass (111) through a camera module (120) mounted on a laser welding machine (110) (S110). Then, coordinate data for a welding line (L) through which a laser passes through the protective glass (111) can be transmitted and received (S120). After that, a monitoring image (141) including the welding line (L) can be obtained by matching the captured image (121) with the coordinate data (S130), and foreign substances can be detected in the obtained monitoring image (141) (S140).

[0068] This is to acquire a monitoring image (141) containing the welding line (L) and to detect foreign substances in the acquired monitoring image (141), as welding defects occur when there are foreign substances on the welding line (L) as described above. Through this, only foreign substances related to welding defects can be detected, thereby improving the speed of foreign substance detection and improving the monitoring efficiency of the protective glass (111).

[0069] After that, the contamination level can be calculated by applying a weight based on the distance between the detected foreign substance and the welding line (L) (S150). Then, the presence or absence of an abnormality in the protective glass (111) can be determined based on whether the calculated contamination level satisfies a preset standard contamination level (S160).

[0070] That is, the protective glass monitoring method according to one embodiment of the present invention can apply a weight based on the distance between the detected foreign substance and the welding line (L), and can quantitatively calculate the contamination level through the application of the weight. And through this, the reliability of determining the contamination level of the protective glass (111) can be increased.

[0071] Additionally, a protective glass monitoring method according to one embodiment of the present invention can calculate the transparency of an area where no foreign substance is detected in an acquired monitoring image (141) (S170). Then, depending on whether the calculated transparency satisfies a preset standard transparency, the presence or absence of an abnormality in the protective glass (111) can be determined (S180).

[0072] This is because, as described above, even in areas not contaminated by foreign substances, the transmission of the laser may vary depending on the degree of transparency of the protective glass (111), and welding defects may occur as a result.

[0073] Accordingly, the protective glass monitoring method according to one embodiment of the present invention can determine that the protective glass (111) is defective if the calculated contamination level does not satisfy a preset standard contamination level or if the calculated transparency level does not satisfy a preset standard transparency level.

[0074] And, a protective glass monitoring method according to one embodiment of the present invention can monitor the protective glass (111) in real time by outputting information (S190) regarding whether there is an abnormality in the determined protective glass (111).

[0075] Furthermore, to increase the reliability of the protective glass (111) monitoring, as illustrated in FIG. 9, the protective glass monitoring method of the present invention subdivides the acquired monitoring image (141) into pixel units (142) (S210), and can detect foreign substances for each subdivided pixel unit (142) (S220).

[0076] Then, the contamination level is calculated for each subdivided pixel (142) unit (S230), and the presence or absence of an abnormality in the protective glass (111) can be determined based on whether the calculated contamination level satisfies a preset standard contamination level (S240).

[0077] At this time, if there is a problem with the protective glass (111) (S241), information that the protective glass (111) needs to be replaced or an alarm may be output (S250). And if it is determined that there is no problem with the protective glass (111), information related thereto may be output (S290).

[0078] In addition, transparency can be calculated for each pixel (142) unit in which no foreign substance is detected at the subdivided pixel (142) unit (S260), and whether there is an abnormality in the protective glass (111) can be determined based on whether the calculated transparency satisfies a preset standard transparency (S270).

[0079] At this time, if there is a problem with the protective glass (111) (S241), information that the protective glass (111) needs to be replaced or an alarm may be output (S250). And if it is determined that there is no problem with the protective glass (111), information related thereto may be output (S290).

[0080] To summarize the above, the protective glass monitoring system and method according to the present invention can predict the replacement time of the protective glass by monitoring the protective glass of a laser welding machine in real time. In addition, it can minimize unnecessary replacement of the protective glass by increasing the reliability of determining the contamination level of the protective glass.

[0081] The foregoing detailed description should not be interpreted restrictively in all respects and should be considered exemplary. The scope of the invention shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention.

Claims

1. In a protective glass monitoring system for a laser welding machine, A camera module mounted on the laser welding machine to capture an image of the protective glass; A communication module that transmits and receives coordinate data for a welding line through which a laser penetrates the protective glass; A detection module that matches the captured image with the coordinate data to obtain a monitoring image including the welding line, and detects foreign substances in the obtained monitoring image; A judgment module that calculates the contamination level by applying a weight based on the distance between the detected foreign substance and the welding line, and determines whether the protective glass is abnormal based on whether the calculated contamination level satisfies a preset standard contamination level; and A protective glass monitoring system comprising an output module that outputs information regarding the presence or absence of abnormalities in the protective glass determined above.

2. In Paragraph 1, The above detection module is, A protective glass monitoring system characterized by subdividing the above-mentioned acquired monitoring image into pixel units and detecting foreign substances for each subdivided pixel unit.

3. In Paragraph 2, The above judgment module is, A protective glass monitoring system characterized by calculating the contamination level for each of the above-detailed pixel units.

4. In Paragraph 1, The above weights are, The closer the distance between the detected foreign substance and the welding line, the higher the value, and The above judgment module is, A protective glass monitoring system characterized by determining that the protective glass is defective if the above-determined contamination level exceeds a preset standard contamination level.

5. In Paragraph 1, The above judgment module is, A protective glass monitoring system characterized by calculating the transparency of an area where no foreign substances are detected in the above-mentioned monitoring image, and determining whether there is an abnormality in the protective glass based on whether the calculated transparency satisfies a preset standard transparency.

6. In Paragraph 5, The above judgment module is, A protective glass monitoring system characterized by determining that the protective glass is defective when the above-mentioned contamination level does not satisfy a preset standard contamination level or when the above-mentioned transparency level does not satisfy a preset standard transparency level.

7. In Paragraph 5, The above detection module is, The above-mentioned acquired monitoring image is subdivided into pixel units, and foreign substances are detected for each subdivided pixel unit, The above judgment module is, A protective glass monitoring system characterized by calculating transparency for each pixel unit in which no foreign substances are detected at the above-mentioned subdivided pixel unit.

8. In Paragraph 1, The above laser welding device is, A main body that emits a laser; A plurality of mirrors arranged so that the emitted laser is reflected and passes through the protective glass; and A protective glass monitoring system characterized by including a welding camera that acquires coordinate data for the welding line and transmits it to the communication module.

9. In Paragraph 7, The above camera module is, A protective glass monitoring system characterized by including a CCD camera configured to capture an image of the protective glass through the plurality of mirrors.

10. A method for monitoring the protective glass of a laser welding machine, A step of capturing an image of the protective glass through a camera module mounted on the laser welding machine; A step of transmitting and receiving coordinate data for a welding line through which a laser penetrates the protective glass; A step of obtaining a monitoring image including the welding line by matching the above-mentioned captured image with the above-mentioned coordinate data; A step of detecting foreign substances in the above-mentioned acquired monitoring image; A step of calculating the contamination level by applying a weight based on the distance between the detected foreign substance and the welding line; A step of determining whether there is an abnormality in the protective glass based on whether the above-described contamination level satisfies a preset standard contamination level; and A protective glass monitoring method comprising the step of outputting information regarding whether there is an abnormality in the protective glass determined above.

11. In Paragraph 10, The step of detecting the above foreign substance is, A protective glass monitoring method characterized by subdividing the acquired monitoring image into pixel units and detecting foreign substances for each subdivided pixel unit.

12. In Paragraph 11, The step of calculating the above contamination level is, A protective glass monitoring method characterized by calculating the contamination level for each of the above-detailed pixel units.

13. In Paragraph 10, The above weights are, The closer the distance between the detected foreign substance and the welding line, the higher the value, and The step of determining whether there is an abnormality in the above protective glass is, A protective glass monitoring method characterized by determining that the protective glass is defective if the above-described contamination level exceeds a preset standard contamination level.

14. In Paragraph 10, The method further includes the step of calculating the transparency of the area where no foreign substances are detected in the above-mentioned monitoring image, The step of determining whether there is an abnormality in the above protective glass is, A protective glass monitoring method characterized by determining whether there is an abnormality in the protective glass based on whether the transparency calculated above satisfies a preset standard transparency.

15. In Paragraph 14, The step of determining whether there is an abnormality in the above protective glass is, A protective glass monitoring method characterized by determining that the protective glass is defective when the above-described contamination level does not satisfy a preset standard contamination level or when the above-described transparency level does not satisfy a preset standard transparency level.

Images