Optical system-based control method and vision inspection device using same

Abstract

The present invention relates to an optical system-based control method and a vision inspection device and, more specifically, to a vision inspection device for using an optical system to inspect the appearance of a secondary battery and a control method therefor. According to an embodiment of the present invention, provided may be the vision inspection device comprising: an optical system including a camera for acquiring an image by imaging a secondary battery and a lighting device for supplying light to the periphery of the secondary battery; and a main controller for determining, on the basis of the image acquired via the optical system, whether the secondary battery is defective. The main controller includes a lighting controller that corrects and controls the illuminance of the lighting device to supply the light at a standard illuminance by selecting a weight for correcting the illuminance of the lighting device to the standard illuminance and applying, to the lighting device, a correction control value obtained by reflecting the weight to a standard control value.

Description

Optical system standard control method and vision inspection device applying the same

[0001] The present invention relates to a standard control method for an optical system and a vision inspection device, and more specifically, to a vision inspection device for inspecting the appearance of a secondary battery using an optical system and a control method thereof.

[0002] This application claims the benefit of priority to Republic of Korea Patent Application No. 10-2024-0013690, dated January 30, 2024, and Republic of Korea Patent Application No. 10-2025-0012278, dated January 31, 2025, the entire contents of which are incorporated herein by reference.

[0003] With the proliferation of portable, small-sized electronic devices, development of new types of secondary batteries, such as nickel-metal hydride batteries and lithium secondary batteries, is actively underway. Recently, lithium secondary batteries are being widely used not only in power tools but also in automobiles.

[0004] A lithium secondary battery is a battery that uses carbon such as graphite as an anode active material, an oxide containing lithium as an anode material, and a non-aqueous solvent as an electrolyte.

[0005] These secondary batteries are manufactured in the form of a battery assembly, with the electrode assembly, in which the positive electrode, separator, and negative electrode are sequentially measured, housed in an outer packaging such as a pouch or cylindrical can. Subsequently, an electrolyte is injected into the battery assembly using an electrolyte injection device. Depending on the shape of the outer packaging, secondary batteries can be categorized into pouch, cylindrical, and prismatic types.

[0006] Pouch-type secondary batteries offer the advantage of high energy density per volume due to their relatively small volume and weight of the outer packaging. Furthermore, when forming battery modules using pouch-type secondary batteries, the small voids also provide the advantage of high energy density per volume.

[0007] Cylindrical secondary batteries have the advantage of being manufactured faster than other types of secondary batteries, and the cylindrical can (outer material) and cap can be manufactured using nickel-plated steel sheets, so the secondary batteries themselves have the advantage of high durability and strength.

[0008] After the secondary battery is manufactured, an appearance inspection can be performed. This appearance inspection can be performed automatically using a vision inspection device utilizing an optical system.

[0009] An optical system is a device that collects and refracts light to create an optical image of an object. Therefore, the optical system includes a lighting device and a camera, and the resulting image is used to inspect the appearance of secondary batteries.

[0010] More specifically, multiple images can be acquired by taking pictures using a camera and multi-lighting, and an inspection algorithm can be performed using the original image and the processed image to automatically determine whether there is an appearance defect.

[0011] Intensity can be used as one of the features in inspection algorithms, and intensity is a crucial factor in determining whether a product is defective. Here, intensity refers to the intensity of light (illuminance). During inspection, specific areas in the image can be identified and the average intensity of that area or the intensity deviation between the defective area and its surroundings can be used to determine whether a product is defective.

[0012] Intensity is closely related to lighting. In vision inspection equipment utilizing optical systems, variations in intensity can occur when taking images using the same optical system, depending on factors such as the lighting itself, installation conditions, and usage time.

[0013] For example, due to the nature of mass-produced secondary batteries, multiple optical systems may be used to perform visual inspection. Each optical system can use the same product (model) and capture images with the same lighting settings. Furthermore, inspection can be performed using the same inspection algorithm.

[0014] However, as previously mentioned, differences in intensity occur in images acquired by different optical systems, resulting in differences in detection capabilities. In other words, a secondary battery in the same condition may be judged as normal when inspected using one optical system, but defective when inspected using another. This can be attributed to differences in intensity across optical systems.

[0015] Therefore, reducing differences in detection power requires intensity adjustments, requiring individual lighting settings for each optical system. This can be a cumbersome and time-consuming process. In particular, since detection power declines whenever illuminance decreases due to lighting aging, a proactive approach to preventing this decline is essential.

[0016] In particular, multiple production lines may be installed within the same production site, each equipped with a vision inspection device. Furthermore, multiple production sites for the same product may be located domestically or internationally. Therefore, individually adjusting lighting settings for countless identical optical systems can be a significant challenge.

[0017] Therefore, it is necessary to devise a method to easily set standards for optical systems and, in particular, to set the intensity of light to a constant level.

[0018] The present invention aims to solve problems of conventional vision inspection devices or vision inspection systems.

[0019] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof that can perform consistent and accurate vision inspection by uniformly implementing standard illuminance for each optical system.

[0020] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof that can easily eliminate deviations in light intensity when taking pictures using the same optical system despite differences in lighting of each optical system, installation status, and usage time.

[0021] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof capable of implementing consistent illuminance for each illumination channel when each optical system has multiple illumination channels.

[0022] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof that can easily correct and control the current illuminance to a standard illuminance through a lighting controller that applies a control value to a lighting device.

[0023] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof that can easily implement correction control logic by utilizing the linear relationship between the illumination intensity and the exposure time of the lighting device.

[0024] Through one embodiment of the present invention, it is intended to provide a vision inspection device and a control method thereof that can maintain consistent and identical detection power in inspection devices with the same illumination brightness and the same inspection algorithm by reducing the difference in illumination between optical systems of the inspection device.

[0025] In order to achieve the above-described purpose, according to one embodiment of the present invention, there is provided a vision inspection device having an optical system including a camera for photographing a secondary battery to obtain an image and a lighting device for supplying light around the secondary battery, and a main controller for determining whether the secondary battery is defective based on the image obtained through the optical system, wherein the main controller selects a weight for correcting the illuminance of the lighting device to a standard illuminance, and applies a correction control value reflecting the weight to the standard control value to the lighting device, thereby providing a vision inspection device including an illuminance controller for correcting the illuminance of the lighting device to supply light at the standard illuminance.

[0026] The illuminance provided by the lighting device may vary depending on the control value applied. A specific control value may be applied so that the lighting device provides a standard illuminance. However, even if a specific control value is applied, the illuminance provided by the lighting device may differ from the standard illuminance due to various variables. Therefore, when a difference occurs between the current illuminance and the standard illuminance, a weighting factor may be selected to eliminate such a difference. By applying a correction control value reflecting such a weighting factor to the lighting device, the lighting device can be enabled to provide the standard illuminance.

[0027] The above control value may be a value corresponding to the time during which the lighting device receives light, i.e., the exposure time.

[0028] It is preferable that the above lighting device have a linear relationship between the applied control value and the illuminance.

[0029] The above optical systems are provided in multiple numbers, and the weights can be selected for each optical system.

[0030] A manufacturing facility for manufacturing secondary batteries may have multiple manufacturing lines arranged in parallel. Each manufacturing line may be equipped with an optical system. In this case, it is desirable for all optical systems on each manufacturing line to be controlled to achieve a standard illuminance.

[0031] Because secondary battery manufacturing is performed in very large quantities, multiple identical manufacturing facilities may be installed. In other words, a single factory may have multiple identical manufacturing facilities. Of course, the same manufacturing facilities can also be located in different factories. When manufacturing identical secondary batteries, consistent and standardized inspections must be performed. Therefore, it would be desirable for all optical systems in each manufacturing facility to be controlled to achieve a standardized illuminance.

[0032] For this purpose, according to the present embodiment, it is preferable that the lighting controller be provided for each optical system.

[0033] The above lighting device includes multiple lighting channels with different lighting positions and areas, and the camera can acquire multiple images by varying the lighting channels. The lighting channels can be implemented in multiple ways by combining the on and off states of multiple light sources with different positions.

[0034] The number of lighting channels that can be implemented in a single lighting device can be preset. However, testing can also be performed using only a limited number of lighting channels. Since illuminance can vary across lighting channels in a lighting device, it is desirable to assign weights to each lighting channel. In other words, it is desirable to apply a control value that reflects the weights for each lighting channel, thereby providing a standard brightness for each lighting channel.

[0035] The above weight may be a ratio of a preset standard brightness to the measured brightness, which is the brightness of an image acquired by applying the above standard control value. The brightness of an image acquired by applying the standard control value through a standard optical system may be preset as the standard brightness. The brightness of an image acquired by applying the standard control value through the current optical system, i.e., the optical system to be controlled, may be measured. Even though the standard optical system and the current optical system are the same model, the preset standard brightness and the currently measured brightness may differ. A weight may be calculated to eliminate such a difference. The weight may be a value obtained by dividing the standard brightness value by the measured brightness value.

[0036] These weights can be considered to utilize the linear relationship between brightness and the control value. For example, when a standard control value is applied, the measured brightness may differ from the standard brightness due to various variables. Therefore, the ratio of the measured brightness to the standard brightness can be calculated and set as the current weight (gain). This weight calculation can be performed multiple times. In other words, the weights can be adjusted until the current brightness matches the standard brightness.

[0037] According to one embodiment of the present invention, a standard optical system for selecting the standard brightness may be further included. That is, the illuminance obtained by applying a standard control value to the standard optical system may be selected as the standard brightness value.

[0038] The above optical system and the standard optical system are identical products, and it is desirable to obtain images under identical conditions and through identical standard control values.

[0039] The above vision inspection device can be operated including an inspection mode in which a secondary battery is photographed while reflecting the weight and a selection mode in which a gray target is photographed while reflecting a temporary weight and the weight is selected.

[0040] For example, if the standard brightness value and the current brightness value are the same, or if the current brightness value is within the allowable range of the standard brightness value, the weight may not be reflected. That is, the weight may be set to 1.

[0041] For example, if the current brightness value falls outside the acceptable range of the standard brightness value, a temporary weight can be calculated, and illuminance correction control can be performed based on this temporary weight. Then, if the current brightness value falls within the acceptable range of the standard brightness value, the temporary weight can be selected as the final weight. In other words, the temporary weight can be repeatedly calculated before a final weight is selected.

[0042] In order to achieve the above-described object, according to one embodiment of the present invention, a control method for a vision inspection device can be provided, including a brightness measurement step of determining a measured brightness through an image obtained by applying a standard control value to an optical system; a weight selection step of comparing the measured brightness with a standard brightness and selecting a weight that is a ratio of the standard brightness to the measured brightness; and an inspection step of determining whether a secondary battery is defective through an image of the secondary battery obtained by applying a correction control value reflecting the selected weight to the standard control value to the optical system.

[0043] The standard brightness can be measured and determined through an image acquired under a standard control value applied through a standard optical system. The brightness can be measured through an image acquired by applying a standard control value to an optical system to be used currently under the same conditions as the standard optical system. Here, the brightness of the acquired image needs to be corrected to become the standard brightness. Here, the linear relationship between the control value and the brightness can be utilized. In particular, the time for which the lighting device receives light, i.e., the exposure time, is set as the control value, and by correcting the exposure time, the brightness of the acquired image can become the standard brightness.

[0044] The above optical system includes a camera and a lighting device, and it is preferable that the standard control value or correction control value is applied to the lighting device through a lighting controller, and the selection of the weight and the determination of whether it is defective are performed through a main controller.

[0045] In the above brightness measurement step, it is preferable to acquire an image of a gray target that is distinct from the secondary battery. In addition, in the inspection step, an image of the secondary battery, which is the actual inspection target, is acquired.

[0046] The above standard brightness is preferably determined through a standard optical system that acquires images under the same conditions and standard control values ​​as the above optical system using the same product.

[0047] It is preferable that the above control value is a value corresponding to the time during which the lighting device receives light, i.e., the exposure time.

[0048] In the vision inspection device according to the present embodiment, it is preferable to select and use a lighting device having a linear relationship between the applied control value and the illuminance.

[0049] The selection mode in which the brightness measurement step and the weight selection step are performed and the inspection mode in which the inspection step is performed can be performed exclusively in a single optical system. This is because the photographing objects in the selection mode and the inspection mode are different.

[0050] It is preferable that the above optical systems are provided in multiple numbers, and that the weights are selected for each optical system.

[0051] It is desirable that the above selection mode and inspection mode be performed for each optical system.

[0052] If the measured brightness is outside the allowable range of the standard brightness, a temporary weight is fed back and used in the brightness measurement step, and if the measured brightness is within the allowable range of the standard brightness, the current temporary weight is preferably selected as the final weight.

[0053] The selection mode is performed by photographing a gray target, and the illumination of the optical system is corrected through the selection mode. After that, the secondary battery, which is the inspection target, can be photographed using the corrected illumination.

[0054] The present invention can solve problems of conventional vision inspection devices or vision inspection systems.

[0055] Through one embodiment of the present invention, a vision inspection device and a control method thereof can be provided that can perform consistent and accurate vision inspection by uniformly implementing standard illuminance for each optical system.

[0056] Through one embodiment of the present invention, a vision inspection device using an optical system can be provided, which can easily eliminate the deviation in light intensity when taking pictures using the same optical system despite the deviation in the lighting itself for each optical system and the difference in installation status and usage time, and a control method thereof.

[0057] Through one embodiment of the present invention, when each optical system has multiple lighting channels, a vision inspection device capable of implementing consistent illuminance for each lighting channel and a control method thereof can be provided.

[0058] Through one embodiment of the present invention, a vision inspection device and a control method thereof can be provided that can easily correct and control the current illuminance to a standard illuminance through a lighting controller that applies a control value to a lighting device.

[0059] Through one embodiment of the present invention, a vision inspection device and a control method thereof can be provided that can easily implement correction control logic by utilizing the linear relationship between the illumination intensity and the exposure time of the lighting device.

[0060] Through one embodiment of the present invention, a vision inspection device and a control method thereof can be provided that can maintain consistent and identical detection power in inspection devices with the same illumination brightness and the same inspection algorithm by reducing the difference in illumination between optical systems of the inspection device.

[0061] Figure 1 illustrates an optical system applicable to one embodiment of the present invention.

[0062] Fig. 2 illustrates an example of an illumination channel through the illumination device of the optical system illustrated in Fig. 1.

[0063] FIG. 3 illustrates images obtained through a vision inspection device according to an embodiment of the present invention and a composite image thereof.

[0064] Figure 4 illustrates a control configuration diagram of a vision inspection device (system) according to one embodiment of the present invention.

[0065] Figure 5 shows the linear relationship between the exposure time of the lighting device and the illuminance (brightness value) in the acquired image.

[0066] Figure 6 illustrates a gray target for measuring a standard brightness value and calculating the standard brightness value through an image obtained using the same.

[0067] Figure 7 illustrates a control flow for selecting a standard brightness value.

[0068] Figure 8 illustrates a control flow for selecting weights,

[0069] Figure 9 illustrates the control flow of the vision inspection device.

[0070] Hereinafter, a vision inspection device according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0071] FIG. 1 illustrates an example of an optical system (10) applicable to one embodiment of the present invention, and FIG. 2 illustrates a lighting channel configuration. In particular, FIG. 1 illustrates a cross-section of a lighting device (30).

[0072] The optical system (10) may include a camera (20) and a lighting device (30). The camera (20) is configured to capture an image by photographing a target object, i.e., a secondary battery, and the lighting device (30) may be configured to supply light to the area around the target object, i.e., the secondary battery.

[0073] The optical system and vision inspection device including the same according to the present embodiment may be used to determine whether a secondary battery is defective by capturing an image of its exterior. In particular, it may be used to determine whether a cylindrical secondary battery is defective, and more preferably, it may be used to capture a planar image of the upper surface, i.e., the cap, of the cylindrical secondary battery to perform an exterior inspection related to the cap.

[0074] As illustrated, the lighting device (30) may include a main body (21) and a lighting housing (35). The lighting device (30) provides lighting toward the subject (40) from above the subject (40), and an image of the subject (40) may be generated through a camera (20) located above the lighting device (30). Here, the subject (40) may be a cylindrical secondary battery.

[0075] The main body (21) can be formed in a cylindrical shape having a hollow space (32), and the hollow space (32) forms an optical path for light projected onto the subject (40) to be reflected to the camera.

[0076] The above lighting housing (35) is located at the lower part of the main body (21) and may likewise be formed in a cylindrical shape. A through hole (35a) corresponding to the hollow (32) of the main body (31) may be formed in the upper center of the lighting housing (35).

[0077] A dome-shaped light guide plate (36) may be provided inside the above lighting housing (35). The light guide plate (36) may be configured to perform a uniform lighting function. The light guide plate (36) may be provided to perform a light diffusion function. By diffusion of light, light from a light source can be diffused along a surface so that the color and brightness appear uniform throughout the screen. Therefore, the light guide plate (36) may be referred to as a light guide diffusion plate.

[0078] A half mirror (34) may be provided in the hollow space (32) of the above body (31). The half mirror may also be referred to as a one-way mirror, and may be said to be a semi-transparent mirror that transmits light in one direction and reflects light in the other direction.

[0079] The above half mirror (34) can be provided to transmit light vertically reflected from the subject (40) and project vertical light onto the subject (40).

[0080] Since the above-mentioned subject, especially the cylindrical secondary battery, is formed in a circular shape, it is preferable that the subject (30) be positioned at the center of the lighting housing (35) so that uniform lighting is provided along the circumferential direction.

[0081] The above lighting device (30) may be equipped with multiple light sources, and may form multiple lighting channels depending on the location of the light sources. A lighting channel may refer to a lighting mode that can be implemented in a single lighting device (30). Accordingly, the on / off of each of the multiple light sources is independently controlled, and various lighting channels can be implemented through combinations of the on / off of the multiple light sources.

[0082] For example, a first light source (33) may be provided on the outside of the hollow (32) of the main body (31). The first light source projects light toward the half mirror, and the light projected onto the half mirror may be reflected and projected vertically upwards onto a vertical subject (40).

[0083] A second light source (37) may be provided on the outside of the light guide plate (36). The second light source projects light onto the rear surface of the light guide plate (36), and the light guide plate (36) guides and diffuses the light to provide uniform light in a radial direction toward the subject (40).

[0084] A third light source (38) that projects light in a downward diagonal direction toward the subject (40) may be provided at the lower portion of the above lighting housing (35). In addition, a fourth light source (39) may be provided above the third light source (38).

[0085] Here, the first light source (33) can be called a coaxial light source, the second light source a dome light source, the third light source a low angle light source, and the fourth light source a dark field light source.

[0086] The second light source, the third light source, and the fourth light source may be provided in multiple numbers uniformly in the circumferential direction of the lighting housing (35).

[0087] Figure 2 illustrates an example of a lighting channel that can be implemented through a lighting device (30).

[0088] A coaxial channel (42) may be implemented based on the center, and a ring channel (43) may be implemented outside the coaxial channel (42). A dome channel (44) may be implemented outside the ring channel (43), and a low-angle channel (45) may be implemented outside the dome channel (44). And a dark field channel (46) may be implemented outside the low-angle channel (45).

[0089] Such multiple channel implementations can be realized through the on-off combination of multiple light sources at different locations. Furthermore, the dome channel (44) and the low-angle channel (45) can be divided into four parts along the circumference, each of which can be realized as four sub-channels.

[0090] FIG. 3 is an example of images and a composite image obtained using an optical system according to an embodiment of the present invention.

[0091] The inspection device according to the present embodiment is for performing an external inspection of a cylindrical secondary battery, and specifically, the external inspection can be performed through images of the upper or lower surface of the cylindrical secondary battery.

[0092] For example, the top and bottom surfaces of a cylindrical secondary battery can be formed to have complex curves rather than flat surfaces, and can be formed with radial symmetry. Therefore, accurate inspection can be performed by acquiring images using multiple illumination channels rather than a single one.

[0093] A total of nine images, from FIG. 3(a) to FIG. 3(i), can be acquired through the camera (20) of the optical system (10). Each image can be acquired under a different illumination channel environment. These images can be acquired as black-and-white shading images or converted from color images to black-and-white shading images. In other words, a processed image can be generated from the original image.

[0094] In order to input images into the inspection algorithm, the original images can be appropriately synthesized, and examples of depth images formed by synthesis are shown in FIGS. 3(j) to 3(l).

[0095] The inspection algorithm performs an image processing process that synthesizes depth images from the acquired image (original image) and inputs the synthesized depth images into a machine learning or deep learning algorithm to determine whether the secondary battery is defective. In other words, the inspection algorithm may include both image processing and artificial intelligence (AI) algorithms, or the two may be distinct. In this case, the AI ​​algorithm alone may be referred to as the inspection algorithm.

[0096] Since the inspection algorithm itself using image processing and artificial intelligence may not be within the scope of the present invention, a detailed description thereof will be omitted.

[0097] The inspection device according to the present embodiment includes an optical system (10). Therefore, the inspection device according to the present embodiment may be referred to as a vision inspection device (100).

[0098] The main controller (60) may be provided in the form of a computer (PC) or a programmable logic controller (PLC), and may be provided to determine whether the secondary battery is defective through an inspection algorithm.

[0099] The vision inspection device (100) may be a single vision inspection device (100) including a main controller (60) and a single optical system (10). In addition, the vision inspection device (100) may be a vision inspection system including a main controller (60) and a plurality of optical systems (10).

[0100] Cylindrical secondary batteries are typically mass-produced. Therefore, vision inspection can be performed using a vision inspection system rather than a single vision inspection device. Each optical system (10) can be referred to as a vision inspection device, and a main controller (60) can be provided to manage and operate these devices.

[0101] To accurately perform vision inspection, identical images must be acquired from the same product in the same environment. In other words, a consistent environment must be provided in multiple optical systems (10).

[0102] However, it is not easy to provide a consistent environment among optical systems (10) due to the installation environment, usage period, or external noise. In particular, it is not easy to maintain the brightness (intensity) of light, i.e., illuminance, through the lighting device (30) consistently among optical systems.

[0103] To solve these problems, according to the present embodiment, the optical system (10) may be equipped with a lighting controller (50) that corrects and controls the illuminance of the lighting device (30). In addition, the optical system (10) may include a camera controller (40) that controls the operation of the camera.

[0104] The above optical system (10) can be operated to acquire an image through the operation control of the main controller (60). In detail, the operation of the camera (20) and the lighting device (30) can be controlled by the camera controller (40) and the lighting controller (50). The optical system (10) and the main controller (60) can be connected to each other by wire or wireless communication so that control signals can be transmitted.

[0105] When the above main controller (60) and multiple optical systems (10) are connected in communication, a lighting controller (40) may be provided for each optical system (10), or one lighting controller (40) may be connected in communication with multiple optical systems (10).

[0106] Typically, lighting devices (30) are controlled by turning them on and off, i.e., on / off. When a lighting device (30) operates with multiple lighting channels, the lighting channels are typically implemented by combining the on / off states of light sources. Therefore, even for the same lighting device (30), for example, the illuminance changes over time.

[0107] In contrast, according to the present embodiment, a lighting controller (40) may be provided to maintain a constant illuminance through the lighting device.

[0108] The lighting controller (40) is provided to control the illuminance of the lighting device, and can maintain the illuminance of the lighting device constant by varying the control value applied to the lighting device (30). Here, the control value may be, for example, a current value applied to the lighting device (30), and the illuminance of the lighting device can be varied as the current value is varied.

[0109] First, the lighting controller (40) can be controlled to perform lighting by applying a standard control value to the lighting device (30). The standard control value may be a fixed value, which is a preset reference control value. Of course, the standard control value may also be a value that is uniformly changed and fixed across the entire vision inspection device.

[0110] In the case of an ideal lighting device (30), when a standard control value is applied, the standard illuminance is consistently implemented. However, in the case of a real lighting device (30), the output, i.e., the illuminance, relative to the standard control value may fluctuate over time for various reasons. In other words, a deviation occurs between the standard illuminance and the output illuminance.

[0111] In addition, illuminance deviations may occur even between identical optical systems (10), i.e., optical systems (10) made of the same product or model. That is, even when the same standard control value is applied, different illuminances may be realized between identical optical systems.

[0112] To solve this problem, it is desirable for the lighting controller (40) to apply a correction control value that reflects the weight from the standard control value to the lighting device (30) to correct the illuminance. That is, it is desirable to change the control value applied to the lighting device to achieve consistent illuminance. Here, a standard for changing the control value is required. In other words, it can be said that the selection of the weight is important.

[0113] The weights for calculating the correction control values ​​can be selected in the main controller (60). That is, the main controller (60) can select the weights so that the lighting device (40) consistently implements the standard illuminance.

[0114] There are various factors that determine brightness, or illuminance, in an acquired image. For example, illuminance can be determined through the gain value of a camera sensor, i.e., exposure time, the aperture of a camera lens, or image correction. The inventors have confirmed that illuminance can be determined independently of these factors through a control value applied to a lighting device, and that consistent detection power can be maintained across inspection equipment and / or optical systems through the control value of a lighting controller.

[0115] Here, the lighting controller (40) can be said to be a configuration that can adjust the illuminance by controlling the exposure time, that is, the time for which light is received from the lighting device.

[0116] The inventors were able to confirm that there is a linear relationship between exposure time and intensity.

[0117] As shown in Fig. 5, it was found that the illuminance increased linearly as the exposure time increased. That is, it was confirmed that the increase or decrease in exposure time applied to the lighting device (30) and the increase or decrease in illuminance (intensity) were in a linear relationship.

[0118] Specifically, for an exposure time interval of, for example, 0 to approximately 999 microseconds, the intensity can vary from 0 to approximately 256, and a consistent linear relationship between the exposure time and the intensity can be confirmed. Here, the intensity is a gray level, and the gray level can be expressed in 256 steps.

[0119] It was confirmed that this linear relationship was maintained not only for the illuminance across the entire lighting device (30) but also for each of the multiple lighting channels. However, it was confirmed that the linear relationship was broken when the exposure time exceeded 750. This is expected to be due to saturation caused by the standard gray target for obtaining the standard illuminance.

[0120] Therefore, consistency of illuminance can be ensured by utilizing the linear relationship between illuminance and exposure time for each lighting device or lighting channel within a period of approximately 750 microseconds or less. In other words, the slope of the linear line formed by illuminance and exposure time for each lighting device or lighting channel becomes constant.

[0121] The above exposure time corresponds to a control value applied from the lighting controller (40) to the lighting device (30), and by increasing the control value, for example, the current value, the exposure time can be increased, thereby increasing the illuminance.

[0122] The main controller (60) has a linear relationship and slope value between illuminance and exposure time for each optical system, lighting device, or lighting channel. Therefore, if the current illuminance deviates from the standard illuminance, a weight for reducing the deviation can be calculated. In other words, the product of the slope value and the exposure time value can be referred to as the illuminance change value. In order to change the current illuminance to the standard illuminance, the illuminance deviation, i.e., the illuminance change value, is first calculated, and then the calculated illuminance change value is divided by the slope value to calculate the exposure time change value.

[0123] Ultimately, the main controller (60) selects a weight for correcting the illuminance of the lighting device (30) to the standard illuminance, and the lighting controller (40) applies a correction control value that reflects the weight to the standard control value to the lighting device (30). That is, the illuminance of the lighting device is corrected and controlled through the lighting controller (40), so that the standard illuminance can be consistently implemented in the lighting device.

[0124] Meanwhile, to determine the standard illuminance, it is desirable to prepare a reference lighting device and a gray target. That is, a standard control value is applied to the standard lighting device, an image of the gray target is acquired, and the illuminance of the acquired image can be determined as the standard illuminance.

[0125] Below, the method and control logic for selecting the standard illuminance, i.e., the standard brightness value, are described in detail.

[0126] Fig. 6(a) illustrates a dummy secondary battery equipped with a gray target, and Fig. 6(b) illustrates selecting a standard brightness value from an acquired image.

[0127] As illustrated in Fig. 6, a dummy secondary battery (70) similar to an actual cylindrical secondary battery can be prepared (S1). A jig (71) corresponding to the case of the cylindrical secondary battery can be formed in a black cylindrical shape, and a gray target (72) can be provided on the upper surface of the jig (71).

[0128] The standard lighting device can be configured with the same specifications and products as the lighting device to be used during inspection. Furthermore, the standard lighting device can generate light (S2) by applying a preset standard control value to the standard lighting device to achieve a standard illuminance.

[0129] An image (S3) can be acquired through a standard optical system to which such a standard lighting device is applied. The acquired image (61) can be displayed on the display of the main controller. A region of interest (ROI) can be set as a preset radius range based on the center point of the acquired gray target image, that is, a circular region equal to the radius of an actual cylindrical secondary battery, and the brightness in the region of interest can be measured (S4). The measured brightness can be quantified as a gray level. A higher gray level may indicate a higher brightness value. Through this process, a standard brightness value, that is, a standard illuminance, can be selected (S5). This standard illuminance can also be used as a reference illuminance in an inspection device used for actual inspection.

[0130] By applying standard control values ​​to these standard lighting devices and capturing an image of a standard gray target, a standard brightness value, i.e. a standard gray level, can be obtained.

[0131] Measuring the standard brightness value (S4) and selecting the standard brightness value (S5) can be performed through the main controller (60). Of course, a standard inspection device separate from the vision inspection device (100) may be installed in the laboratory to measure and select the standard brightness value.

[0132] The above standard brightness value can be used in the process of selecting weights in the optical system (10) of an actual vision inspection device.

[0133] Below, the weight selection method and control logic of the optical system are described in detail with reference to Fig. 8.

[0134] First, prepare a gray target (S10), and it is desirable that the gray target be the same as the gray target used when selecting the standard brightness value.

[0135] Afterwards, a standard control value is applied to the lighting device (30) to generate lighting (S20). Afterwards, an image of a gray target can be acquired (S30) through a camera (20). Brightness measurement (S40) is performed through the acquired image. Similarly, the measured brightness value can be digitized into a gray level. The measured brightness value can be compared with a standard brightness value (S50).

[0136] Here, if the measured brightness value is equal to the standard brightness value, this means that the current lighting device (30) implements the standard illuminance when the standard control value is applied. Therefore, illuminance correction control of the current lighting device (30) may be unnecessary for the time being.

[0137] Additionally, the standard brightness value may have a certain tolerance range. That is, it may have a lower standard level (LSL) and an upper standard level (USL). If the measured brightness value is within the tolerance range, the current standard control value does not change, and the current weight can be set to 1 and a weight can be selected (S60).

[0138] However, if the measured brightness value is out of the allowable range, weight calculation (S70) may be performed to match the measured brightness value with the standard brightness value. The weight may be a value obtained by dividing the measured brightness value by the standard brightness value. Once the weight is calculated, a correction control value reflecting the calculated weight may be applied to the lighting device (30) to generate lighting. The initially applied standard control value may be converted into a correction control value reflecting the weight and applied to the lighting device (30). Through this, the illuminance of the lighting device may be corrected and controlled.

[0139] Afterwards, image acquisition (S30), brightness measurement (S40), and brightness comparison (S50) can be performed again. If the brightness measured during the brightness comparison (S50) satisfies the tolerance range, the current weights can be selected as the final weights (S60). Of course, if the tolerance range is not met, new weights can be calculated (S70) and the compensation control can be repeated.

[0140] Through these processes, weights corresponding to the current optical system (10) or lighting device (30) can be selected.

[0141] As described above, one lighting device (30) may have multiple lighting channels. One vision inspection device (100) may have multiple optical systems (10).

[0142] When managing and operating multiple optical systems (10) and multiple lighting channels per optical system in the main controller (60), a serial number or name can be assigned to each optical system, and a name can be assigned to each lighting channel.

[0143] In the main controller (60), weights can be selected and updated for each optical system (10) or for each illumination channel of the optical system. Accordingly, vision inspection can be performed by maintaining the same brightness value for each optical system and / or illumination channel.

[0144] Figure 9 illustrates the driving logic of the vision inspection device.

[0145] The vision inspection device can basically perform an inspection mode (S100) for inspecting a secondary battery by acquiring an image through an optical system (10). Here, the vision inspection device may have a single optical system (10) or may have multiple optical systems (10).

[0146] Various conditions may be applied, such as when the inspection mode is performed for a certain period of time, when the number of images acquired is a certain number, when the number of secondary batteries inspected is a certain number, or when the consistency of the inspection mode is detected to be impaired. In other words, conditions for performing weight selection and weight update may be applied. In other words, a step (S110) for determining whether to proceed with the selection mode (S120) for selecting or updating weights may be performed.

[0147] If the conditions for selection mode progression are met during inspection mode execution, inspection mode may be stopped and selection mode (S120) may be initiated. In the first selection mode, weights are selected, and in subsequent selection modes, the previous weights may be replaced with new weights and selected.

[0148] When the selection mode (S120) is terminated, the selection mode progress conditions are initialized (S130), and the inspection mode can be performed thereafter by reflecting the selected weights.

[0149] Here, when the inspection device has multiple optical systems (10), the inspection mode and selection mode can be performed independently for each optical system, or can be performed collectively for each optical system. When there are multiple conditions for entering the selection mode (S120), it is preferable that the inspection mode and selection mode be performed independently for each optical system. This is because, when the selection mode is performed, the inspection process, which is part of the manufacturing process, inevitably has to be stopped. Therefore, for the efficiency of the entire manufacturing process, it is preferable to perform the inspection mode and selection mode independently for each optical system.

[0150] As described in the detailed description of the invention.

Claims

1. A vision inspection device having an optical system including a camera that captures an image of a secondary battery and a lighting device that supplies light around the secondary battery, and a main controller that determines whether the secondary battery is defective based on the image acquired through the optical system, The above main controller selects a weight for correcting the illuminance of the lighting device to the standard illuminance, A vision inspection device including a lighting controller that applies a correction control value reflecting the above weight to the standard control value to the lighting device, thereby correcting and controlling the illuminance of the lighting device to supply light at a standard illuminance.

2. In paragraph 1, A vision inspection device characterized in that the above control value is a value corresponding to the time (exposure time) during which the lighting device receives light.

3. In paragraph 1, A vision inspection device characterized in that the lighting device has a linear relationship between the applied control value and the illuminance.

4. In paragraph 3, A vision inspection device characterized in that the above optical systems are provided in multiple numbers and the weights are selected for each optical system.

5. In paragraph 4, A vision inspection device characterized in that the lighting controller is provided for each of the optical systems.

6. In paragraph 3, A vision inspection device characterized in that the lighting device includes a plurality of lighting channels having different lighting positions and areas, and the camera acquires a plurality of images by varying the lighting channels.

7. In paragraph 6, A vision inspection device characterized in that the weights are selected for each of the above lighting channels.

8. In any one of paragraphs 1 to 7, A vision inspection device characterized in that the above weight is a ratio of a pre-selected standard brightness to a measured brightness, which is the brightness of an image obtained by applying the above standard control value.

9. In paragraph 9, A vision inspection device characterized by further including a standard optical system for selecting the above standard brightness.

10. In paragraph 9, A vision inspection device characterized in that the above optical system and the standard optical system are identical products and acquire images through identical conditions and identical standard control values.

11. In paragraph 8, The vision inspection device is characterized in that it has an inspection mode that photographs a secondary battery while reflecting the weight and determines whether the inspection object is defective, and a selection mode that photographs a gray target while not reflecting the weight or reflecting a temporary weight and selects the weight.

12. A brightness measurement step for deriving the measured brightness through an image obtained by applying a standard control value to the optical system; A weight selection step for selecting a weight that is the ratio of the standard brightness to the measured brightness by comparing the measured brightness with the standard brightness; and A control method for a vision inspection device, including an inspection step of determining whether a secondary battery is defective through an image of the secondary battery obtained by applying a correction control value reflecting the selected weight to the standard control value to the optical system.

13. In paragraph 12, A control method for a vision inspection device, characterized in that the optical system includes a camera and a lighting device, the standard control value or the correction control value is applied to the lighting device through a lighting controller, and the selection of the weight and the determination of whether there is a defect are performed through a main controller.

14. In paragraph 13, A control method for a vision inspection device, characterized in that in the above brightness measurement step, an image of a gray target that is distinguished from the secondary battery is acquired.

15. In paragraph 14, A control method for a vision inspection device, characterized in that the above standard brightness is determined through a standard optical system that acquires an image through the same conditions and the same standard control value as the above optical system.

16. In paragraph 13, A control method for a vision inspection device, characterized in that the above control value is a value corresponding to the time (exposure time) during which the lighting device receives light.

17. In paragraph 16, A control method for a vision inspection device, characterized in that the lighting device has a linear relationship between the applied control value and the illuminance.

18. In paragraph 12, A control method for a vision inspection device, characterized in that the selection mode in which the brightness measurement step and the weight selection step are performed and the inspection mode in which the inspection step is performed are performed exclusively in a single optical system.

19. In paragraph 18, A control method for a vision inspection device, characterized in that a plurality of optical systems are provided and the weights are selected for each optical system.

20. In paragraph 12, If the above measured brightness is outside the allowable range of the above standard brightness, a temporary weight is fed back and used in the above brightness measurement step. A control method for a vision inspection device, characterized in that when the measured brightness is within the allowable range of the standard brightness, the current temporary weight is selected as the final weight.

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