Secondary battery stack vision imaging system and secondary battery stack vision inspection method thereof

Abstract

A secondary battery stack vision inspection method according to the present invention comprises the steps of: fixing a separator in a bent state to a stack table; fixing a first electrode and a second electrode to first and second pick-and-place units to combine the first electrode and second electrode with the separator; gripping a stack cell, combined with the separator, by a cell gripper made of a light guide plate material; and transferring the stack cell to the stack table and performing stack inspection through stack vision imaging.

Description

Secondary battery stack vision imaging system and secondary battery stack vision inspection method thereof

[0001] The present invention relates to a secondary battery stack vision imaging system and a secondary battery stack vision inspection method thereof. The present application claims the benefit of priority based on Korean Patent Application No. 10-2025-0010820 filed January 24, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of the specification.

[0002] With rising energy prices due to the depletion of fossil fuels and growing concern over environmental pollution, the need for eco-friendly alternative energy sources is becoming increasingly important. Various power generation technologies, such as nuclear, solar, wind, and tidal power, are being researched, and energy storage devices for the efficient use of this generated energy are also receiving significant attention.

[0003] In particular, the need for batteries is surging due to technological development and increasing demand for a wide range of products, from portable electronic devices such as smartphones and laptops to electric vehicles, hybrid electric vehicles, drones, and energy storage systems (ESS), and active research is underway to meet these diverse requirements. Notably, lithium-ion batteries are attracting attention as a representative energy source due to their advantages, such as high energy density, discharge voltage, and output stability, and the demand for lithium-ion batteries, including lithium-ion and lithium-ion polymer batteries, is particularly high.

[0004] A secondary battery consists of an electrode assembly with a stacked structure comprising a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. Such electrode assemblies can be classified into various types depending on their structure. For example, there are jellyroll-type electrode assemblies formed by winding long sheet-type positive and negative electrodes separated by a separator, and stack-type electrode assemblies formed by sequentially stacking multiple positive and negative electrodes cut to a predetermined size separated by a separator.

[0005] In addition, secondary batteries can be classified into various types depending on the case shape. There are cylindrical secondary batteries in which the electrode assembly is embedded in a cylindrical case, prismatic secondary batteries in which it is embedded in a prismatic case, and pouch-type secondary batteries in which it is embedded in a pouch-type case made of a laminate sheet.

[0006] Meanwhile, reducing unit costs in the battery manufacturing process is a critical task for securing industrial competitiveness, and increasing the speed of production facilities is essential to achieve this. In particular, it is important to enhance the productivity of the stacking process, which involves stacking the electrodes and separators that constitute the battery cell.

[0007] In the commonly used zigzag stacking process, a technology is being developed to simultaneously load negative and positive electrodes during a single pick-and-place process to improve production speed.

[0008] However, this 2-cell (anode / anode) simultaneous stacking method has limitations in real-time measuring Critical to Quality (CTQ) items, such as the gap between the anode and cathode and the gap between the anode and separator, which are important for quality control in the stacking process. CTQ items directly affect the final quality of the battery, including performance, stability, and lifespan; failure to manage them can lead to an increase in product defect rates or a degradation of electrochemical performance. Therefore, while the introduction of 2-cell simultaneous stacking technology offers the advantage of increased productivity, technical improvements are required to address the issues of measuring and managing CTQ items.

[0009] An embodiment of the present invention provides a secondary battery stack vision imaging system and a secondary battery stack vision inspection method thereof, which can improve process quality by effectively verifying the spacing and alignment state between electrodes during the stacking process by accurately inspecting the position of the negative electrode located at the bottom through the stacked separator in a simultaneous stacking method in which 2 cells (negative / positive) are stacked at once.

[0010] However, the technical problem that this embodiment aims to solve is not limited to the technical problem described above, and other technical problems may exist.

[0011] As a technical means for achieving the technical problem described above, a secondary battery stack vision inspection method according to the first aspect of the present invention comprises the steps of: fixing a separator in a folded state to a stack table; fixing a first electrode and a second electrode to first and second pick-and-place units to align them with the separator; gripping a stack cell aligned with the separator using a cell gripper made of a light guide plate material; and transferring the stack cell to the stack table to perform a stack inspection through stack vision imaging.

[0012] In some embodiments of the present invention, the step of fixing the first electrode and the second electrode to the first and second pick-and-place units and combining them with the separator is such that the first electrode is an anode and the second electrode is a cathode, and the first electrode, the separator, and the second electrode may be combined in the order of the first electrode, the separator, and the second electrode based on the spread separator.

[0013] In some embodiments of the present invention, the cathode may be configured to have a greater overall width and overall length than the anode.

[0014] In some embodiments of the present invention, the step of the cell gripper gripping the stack cell combined with the separator may include: the step of an upper cell gripper entering the upper part of the stack cell; the step of a lower cell gripper entering the upper part of the stack cell; and the step of the upper cell gripper and the lower cell gripper gripping the stack cell.

[0015] Some embodiments of the present invention may further include the step of the first and second pick-and-place units breaking the fixed state and returning to their original positions after the stack cell is gripped.

[0016] In some embodiments of the present invention, the step of transferring the stack cell to the stack table and performing a stack inspection through stack vision imaging may include: the step of the upper cell gripper that has entered the upper part of the stack cell moving backward and withdrawing; the step of the cell pressing jig descending to the upper part of the stack cell to fix the stack cell; and the step of emitting light from the light guide plate of the lower cell gripper.

[0017] In some embodiments of the present invention, the lower cell gripper of the light guide plate material may be made of acrylic material.

[0018] In some embodiments of the present invention, the lower cell gripper of the light guide plate material may have an LED attached to its side and be used as a light source.

[0019] The step of transferring the stack cell to the stack table and performing a stack inspection through stack vision imaging can verify the stack quality by measuring the gap (Gab) between the cathode, separator, and anode of the stack cell.

[0020] In addition, a secondary battery stack vision imaging system according to the second aspect of the present invention includes a stack table on which a stack cell combined with a separator is placed, a cell gripper including a light guide plate that grips the stack cell and transfers it to the stack table, a vision camera that performs vision imaging for inspection of the stack cell, and a cell pressing jig that descends onto the top of the stack cell during vision imaging to fix the stack cell.

[0021] In some embodiments of the present invention, the cell gripper includes an upper cell gripper that enters the upper part of the stack cell and a lower cell gripper that enters the lower part of the stack cell, wherein the light guide plate may be included in the lower cell gripper.

[0022] In some embodiments of the present invention, the light guide plate included in the lower cell gripper may be made of an acrylic material.

[0023] In some embodiments of the present invention, the lower cell gripper may include an LED attached to the side and operating as a light-emitting body that emits light from the bottom of the stack cell.

[0024] Some embodiments of the present invention may further include a front light positioned on the upper front of the stack cell for vision imaging of the vision camera, providing a predetermined amount of light and color temperature.

[0025] In some embodiments of the present invention, the colors of the LED and the front light may each be selected as one of the RGB colors and emit light.

[0026] In some embodiments of the present invention, the colors of the LED and the front light may be selected to be the same color and emit light.

[0027] In some embodiments of the present invention, the cell pressing jig can lower and fix the stack cell after the upper cell gripper that has entered the upper part of the stack cell has retracted and withdrawn.

[0028] According to one embodiment of the present invention described above, it is possible to increase the stacking speed by two times compared to the conventional method, thereby significantly improving production efficiency. In particular, it is possible to perform precise quality inspection of the negative stack, thereby preventing quality problems that may occur in the existing process and enabling the production of reliable battery cells.

[0029] In conventional stacking methods, it is often difficult to align the negative and positive electrodes and measure the gap between the electrodes, which can lead to deficiencies in quality inspection. However, according to one embodiment of the present invention, quality inspection of the negative electrode stack is possible, allowing for accurate measurement of the gap between the negative electrode, the positive electrode, and the separator, and enabling rapid detection of gap mismatches or defective electrodes. Through this, it is possible to improve the overall quality of the battery cell and simultaneously expect the effect of reducing the defect rate that may occur on the production line.

[0030] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description below.

[0031] FIG. 1 is a drawing for explaining a secondary battery stack vision imaging system according to one embodiment of the present invention.

[0032] FIG. 2 is a flowchart of a secondary battery stack vision inspection method according to one embodiment of the present invention.

[0033] FIG. 3 is a diagram illustrating the membrane preparation process steps in one embodiment of the present invention.

[0034] FIG. 4a is a front view illustrating the electrode matching process step in one embodiment of the present invention.

[0035] FIG. 4b is a plan view illustrating the electrode matching process step in one embodiment of the present invention.

[0036] FIG. 5a is a front view illustrating the stack cell grip process step in one embodiment of the present invention.

[0037] FIG. 5b is a plan view illustrating the stack cell grip process step in one embodiment of the present invention.

[0038] FIG. 6a is a front view illustrating a stack vision inspection process step in one embodiment of the present invention.

[0039] FIG. 6b is a plan view illustrating a stack vision inspection process step in one embodiment of the present invention.

[0040] FIG. 6c is a drawing for explaining a lower cell gripper in one embodiment of the present invention.

[0041] FIGS. 7a and 7b are drawings for explaining stack vision inspection results according to an embodiment of the present invention.

[0042] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the present invention, and the present invention is defined only by the scope of the claims.

[0043] The terms used in this specification are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. The terms "comprises" and / or "comprising" used in this specification do not exclude the presence or addition of one or more other components in addition to the components mentioned. Throughout the specification, the same reference numerals refer to the same components, and "and / or" includes each of the mentioned components and all combinations of one or more. Although terms such as "first," "second," etc., are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical scope of the invention.

[0044] Unless otherwise defined, all terms used herein (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0045] In the description of the present invention, 'battery' or 'electrode assembly' may be a secondary battery. Additionally, a pouch case housing the electrode assembly may be referred to as a battery cell. A secondary battery may refer to a battery made using a material capable of repeating the oxidation-reduction process between the current and the material multiple times. For example, to produce a secondary battery, processes such as mixing, coating, roll pressing, slitting, notching and drying, lamination, folding and stacking, lamination and stacking, packaging, charging and discharging, degassing, and characteristic testing may be performed. In this case, separate production equipment (devices) may be used to perform each process. Here, each production equipment may be operated by adjustment parameters, set values, etc., set or modified by an operator.

[0046] FIG. 1 is a drawing for explaining a secondary battery stack vision imaging system (1) according to one embodiment of the present invention.

[0047] A secondary battery stack vision imaging system (1) according to one embodiment of the present invention includes a stack table (20), a cell gripper (15), a vision camera (17), and a cell pressing jig (16).

[0048] A stack table (20) on which a stack cell (10) combined with a separator is placed. The stack table (20) ensures the stability of the stack cell (10) and allows the stack cell (10) to maintain an accurate position without moving or twisting. In the preparation stage, the separator is fixed to the stack table (20) in a folded state, and subsequently, an electrode is combined with the separator to form a stack cell (10).

[0049] The cell gripper (15) picks up the stack cell (10) combined with the separator and transfers it to the stack table (20). The cell gripper (15) consists of an upper cell gripper (15a) and a lower cell gripper (15b). The upper cell gripper (15a) enters the upper part of the stack cell (10), and the lower cell gripper (15b) enters the lower part of the stack cell (20). After this, the upper cell gripper (15a) and the lower cell gripper (15b) can simultaneously pick up the stack cell (10) and transfer it to the stack table (20).

[0050] At this time, one embodiment of the present invention is characterized in that the lower cell gripper (15b) includes a light guide plate (151b), and the light guide plate may be made of an acrylic material. The light guide plate provides an even light distribution to optimize the conditions required for vision imaging of the stack cell.

[0051] Additionally, the lower cell gripper (15b) includes an LED (152b) attached to the side and operating as a light source emitting light from the bottom of the stack cell (10). The LED (152b) is utilized as one of the light sources for vision imaging and emits light evenly from the bottom of the stack cell (10) to support accurate imaging of the surface condition of the stack cell (10). The light source of the LED (152b) can adjust the color temperature and brightness, thereby providing optimized lighting for various inspection environments.

[0052] At this time, one embodiment of the present invention may further include a front light (21). The front light (21) provides a constant amount of light and color temperature toward the upper front surface of the stack cell (10) while the vision camera (17) is taking images. The front light (21) serves to improve the image quality of the vision camera (17) by evenly illuminating the upper surface of the stack cell (10). The color of the front light (21) can be selected from RGB colors and can be optimized to match the image conditions of the vision camera (17).

[0053] Meanwhile, the colors of the LED (152b) and the front light (21) can be selected as one of the RGB colors to optimize the inspection environment and increase the accuracy of the image. In one embodiment, the LED (152b) and the front light (21) may be set to the same color so that a uniform color is evenly distributed on the surface of the stack cell (10), thereby providing consistency in vision imaging. The colors of each light (21, 152b) can be adjusted in real time and can be optimized and set to suit the state of the stack cell (10).

[0054] For reference, in FIG. 1, P1 represents the color of the front light (21), and P2 represents the color projected onto the light guide plate (152b) by the LED (152b). The colors of P1 and P2 can each be selected from RGB colors, and if necessary, they can be set to the same color or combined with different colors to provide an optimal lighting environment for inspecting the stack cell (10).

[0055] The vision camera (17) performs imaging for the inspection of the stack cell (10) and captures high-resolution images to accurately evaluate the condition of the stack cell (10). For example, the vision camera (17) may use a near-infrared (NIR) camera or a high-resolution 25M mono camera. The vision camera (17) operates together with a cell pressing jig (16) that fixes the stack cell (10) while the vision imaging is being performed.

[0056] According to an embodiment, a reflective mirror (22) may be provided to assist the vision camera (17) in imaging. The reflective mirror (22) is positioned between the vision camera (17) and the stack cell (10) to adjust the path of light so that the vision camera (17) can image the stack cell (10) from various angles. Through this, a field of view is secured even for areas and angles that are difficult for the vision camera (17) to image directly, thereby enabling effective vision inspection of the stack cell (10). The reflective mirror (22) may be composed of a high-reflectivity material to minimize light loss and may include a support structure that can be adjusted to a desired angle.

[0057] The cell pressing jig (16) fixes the stack cell (10) while vision imaging is in progress. When the upper cell gripper (15a) retracts and moves away, the cell pressing jig (16) descends and presses the stack cell (10) to fix it on the stack table (20). The cell pressing jig (16) minimizes movement of the stack cell (10) and supports accurate imaging by the vision camera (17). Meanwhile, the cell pressing jig (16) can prevent deformation or damage to the stack cell (10) by evenly distributing pressure on the stack cell (10).

[0058] Hereinafter, with reference to FIGS. 2 to 6c, a secondary battery stack vision inspection method performed by a secondary battery stack vision imaging system (1) according to an embodiment of the present invention will be described in more detail.

[0059] FIG. 2 is a flowchart of a secondary battery stack vision inspection method according to one embodiment of the present invention.

[0060] A secondary battery stack vision inspection method according to one embodiment of the present invention comprises the steps of: fixing a separator (11) in a folded state to a stack table (20) (S110); fixing a first electrode and a second electrode to first and second pick-and-place units (14a, 14b) to combine with the separator (11) (S120); gripping a stack cell (10) combined with the separator (11) by cell grippers (15a, 15b) made of a light guide plate material (S130); and transferring the stack cell (10) to the stack table (20) to perform a stack inspection through stack vision imaging (S140).

[0061] FIG. 3 is a diagram illustrating the steps of a separation membrane (11) preparation process in one embodiment of the present invention.

[0062] In the present invention, the separator (11) is first fixed to a stack table (20) in a folded state (S110). The separator (11) is transferred to a designated position on the stack table (20) for stacking operations, and the transferred separator (11) can be fixed by a suction device located on the stack table (20).

[0063] At this time, the adsorption device operates in a vacuum adsorption manner and gently adheres the separator (11) to the surface of the stack table (20) to prevent positional movement or shaking during the process. While the separator (11) is adsorbed and fixed, a portion of the separator (11) is maintained in a folded state. This is to secure space for stacking the negative electrode (13) and positive electrode (12) during the stacking process and to proceed with the process without wrinkles or deformation of the separator (11).

[0064] Additionally, the separator (11) is prepared in a rotated state to match the direction and alignment required for stacking fixation before being fixed to the stack table (20). The rotated separator (11) is placed on the stack table (20) after being precisely adjusted to a specified angle, and once adsorption fixation is completed, the next step, electrode stacking, begins.

[0065] FIG. 4a is a front view illustrating the electrode matching process step in one embodiment of the present invention. FIG. 4b is a plan view illustrating the electrode matching process step in one embodiment of the present invention.

[0066] Next, the first electrode and the second electrode are fixed to the first and second Pick and Place (hereinafter P&P) units (14a, 14b) and combined with the separator (11) (S120). In the electrode combining step, the positive electrode (12) and the negative electrode (13) are individually adsorbed and fixed by the first and second P&P units (14a, 14b), respectively, and then combined with the pre-prepared separator (11) to form a stack.

[0067] At this time, the first electrode is positioned on the upper side of the separator (11) as the anode (12) during the stacking process, and the second electrode is positioned on the lower side of the separator (11) as the cathode (13). This stacking is performed in the order of "anode (12) - separator (11) - cathode (13)" based on the unfolded separator (11). During the stacking process, precise alignment correction is performed on each electrode to maintain alignment with the separator (11). Alignment correction is a process to accurately align the position of each electrode with the separator (11) and other electrodes, minimizing errors to maintain a constant gap between electrodes and ensuring the quality of the stacking process.

[0068] Subsequently, the corrected electrodes are adsorbed by the respective first and second P&P units (14a, 14b). First, the second electrode, the negative electrode (13), is adsorbed by the second P&P unit (14b) and then stacked on the lower part of the separator (11), and then the first electrode, the positive electrode (12), is stacked on the upper part of the separator (11) by the first P&P unit (14a). Accordingly, the separator (11) is positioned between the positive electrode (12) and the negative electrode (13), thereby providing a structure capable of electrochemical reaction of the battery.

[0069] Meanwhile, the cathode (13) used in the above process may be designed to have a larger width and length than the anode (12). This is to ensure a stable electrochemical reaction by ensuring that the cathode (13) sufficiently covers the separator (11) and the anode (12), and to reduce the possibility of a short circuit between the electrodes. In particular, the large width and length of the cathode (13) expand the contact surface with the separator (11) during the stacking process, making it easier to align the positions of the electrodes and preventing misalignment that may occur during the stacking process.

[0070] FIG. 5a is a front view illustrating the stack cell (10) gripping process step in one embodiment of the present invention. FIG. 5b is a plan view illustrating the stack cell (10) gripping process step in one embodiment of the present invention.

[0071] Next, a cell gripper (15a, 15b) made of a light guide plate material grips the stack cell (10) combined with the separator (11) (S130). The stack cell (10) gripping process step is a preliminary step for moving the stack cell (10) to the stack table (20) after accurately fixing it.

[0072] To this end, an upper cell gripper (15a) enters the upper part of the stack cell (10), and a lower cell gripper (15b) enters the lower part of the stack cell (10). Then, the lower cell gripper (15b) works together with the upper cell gripper (15a) to simultaneously secure the stack cell (10) in the up and down directions. A pair of cell grippers (15a, 15b) stably grip the stack cell (10), allowing it to be placed on the stack table (20) without shaking during the process of moving to the stack table (20).

[0073] Next, after the stack cell (10) is gripped, the first and second P&P units (14a, 14b) release the fixed state and return to their original positions. During this process, the first and second P&P units (14a, 14b) separate the electrodes that were previously fixed in an adsorption state and return to their original positions to prepare for the next operation. While the first and second P&P units (14a, 14b) are returning to their original positions, the cell grippers (15a, 15b) move the stack cell (10) to the stack table (20) while holding it in a fixed state.

[0074] FIG. 6a is a front view illustrating a stack vision inspection process step in one embodiment of the present invention. FIG. 6b is a plan view illustrating a stack vision inspection process step in one embodiment of the present invention. FIG. 6c is a drawing for explaining a lower cell gripper (15b) in one embodiment of the present invention.

[0075] Next, the stack cell (10) is transferred to the stack table (20) to perform a stack inspection through stack vision imaging (S140).

[0076] First, the upper cell gripper (15a) that had entered the upper part of the stack cell (10) moves backward and exits from the stack cell (10). At this stage, the upper cell gripper (15a) returns to its original position, thereby enabling stack vision inspection to be performed through the lower cell gripper (15b).

[0077] After the upper cell gripper (15a) is disengaged, the cell pressing jig (16) descends to fix the stack cell (10). The cell pressing jig (16) serves to fix the top of the stack cell (10) by pressing it with a pressing pressure to prevent the stack cell (10) from becoming misaligned while the upper cell gripper (15a) is in a retracted state. When the cell pressing jig (16) descends and fixes the stack cell (10), the stack cell (10) can be inspected through stack vision imaging in a stable state.

[0078] Subsequently, the light guide plate (151b) of the lower cell gripper (15b) emits light. The lower cell gripper (15b) is made of acrylic material and has an LED (152b) attached to its side to be used as a light source. The light guide plate (151b) of the lower cell gripper (15b) is applied as a light source by forming a pattern on its lower surface. This pattern controls the distribution of light and allows the position and status of the cell (10) to be checked. When the light guide plate (151b) emits light through the LED (152b), the position of the stack cell (10) can be visually confirmed, and accurate position tracking of the stack cell (10) is possible during the inspection and monitoring process.

[0079] Next, the stack cell (10) is inspected through a stack vision imaging system (1). The stack vision imaging system (1) checks the stack quality by precisely measuring the position, alignment status, and gap between each electrode of the cell (10). The stack vision imaging system (1) uses a fixed vision camera (17) and a sensor to inspect whether each component of the stack cell (10) is accurately aligned, whether the gap between the electrode and the separator (11) meets the specifications, etc. In particular, it checks whether the quality of the cell (10) meets the standards by measuring the gap between the cathode (13), the separator (11), and the anode (12).

[0080] Additionally, during the stack vision inspection stage, a backlight lighting effect is used while the lower cell gripper (15b) of the light guide plate material is positioned. This lighting effect allows gap measurement to be performed by passing through the separator (11). The backlight makes the components inside the stack cell (10) transparent, thereby enabling accurate identification of the gap between the electrodes, including the separator (11). This allows for more precise evaluation of the quality of the stack cell (10) and enables accurate detection of defective elements.

[0081] Meanwhile, in the above description, steps S110 to S140 may be further divided into additional steps or combined into fewer steps according to an embodiment of the present invention. Also, some steps may be omitted as necessary, and the order between steps may be changed. Furthermore, even if other omitted details are included, the details described in FIG. 1 and the details described in FIG. 2 to 6c are mutually applicable.

[0082] FIGS. 7a and 7b are drawings for explaining stack vision inspection results according to an embodiment of the present invention.

[0083] FIG. 7a is an image obtained from a stack vision inspection result, captured using a color vision camera (17) used in the experiment, a light guide plate LED light (152b, red), and a front light (21, blue). Here, a 25M color camera (resolution: 5120 x 5120, pixel size: 2.5μm) was used as the experimental condition, and a CCTV 25mm lens was applied. The resolution was set to 35μm to enable precise inspection of the stack cell (10). In the inspection result image, the separator (11), cathode (13), and anode (12) constituting the stack cell (10) are clearly distinguished. In particular, the cathode (13) appears in a transparent state after passing through the separator (11), thereby allowing the location and state of the cathode (13) to be accurately confirmed.

[0084] FIG. 7b shows the Gray Value (GV) deviation between the separator (11) and the cathode (13), and between the cathode (13) and the anode (12). In this case, the experimental results are shown in the Blue channel image among the RGB channels. According to the experimental results, the GV deviation between the separator (11) and the cathode (13) was found to be 20, which means a change of approximately 14.29%. In addition, the GV deviation between the cathode (13) and the anode (12) was measured to be 95, which showed a change of approximately 79.17%. Here, the GV deviation value is an indicator representing the accuracy of the gap between electrodes within the stack cell (10). In particular, the gap change between the separator (11) and the cathode (13) was a relatively small change of 14.29%, but the gap change between the cathode (13) and the anode (12) was a significantly large difference of 79.17%, which suggests that a clear gap difference between the electrodes and the separator (11) can be confirmed through the stack vision inspection method according to the present invention.

[0085] At this time, under the above experimental conditions, for the Red channel, the GV deviation from the separator (11) to the cathode (13) was measured as 65 (72.22% change) and the GV deviation from the cathode (13) to the anode (12) was measured as 15 (60.00% change), and for the Green channel, the GV deviation from the separator (11) to the cathode (13) was measured as 20 (44.44% change) and the GV deviation from the cathode (13) to the anode (12) was measured as 20 (80.00% change).

[0086] The GV deviation between the separator (11) and the cathode (13) and the GV deviation between the cathode (13) and the anode (12) according to the conditions of LED lighting (152b) and front lighting (21) are shown in the table below. First, the results of comparing the NIR camera and the 25M mono camera are as shown in Table 1.

[0087] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation NIR Camera Separator: approx. 205 Cathode: approx. 130 Anode: approx. 20--25M Mono Camera Separator: approx. 205 Cathode: approx. 130 Anode: approx. 20--

[0088] < Comparison of NIR Camera and 25M Mono Camera (No LED Illumination) >

[0089]

[0090] According to Table 1, under conditions where LED (152b) lighting was not used, there was only a difference in light intensity between the two cameras, and no difference was observed in the visibility of the cathode inside the camera. In addition, when comparing the responsiveness in the IR (850nm) wavelength band, it was confirmed that the NIR camera showed higher responsiveness than the 25M mono camera. The experimental results in Table 1 show how the characteristics of each camera affect sensitivity and visibility in specific wavelength bands. Table 2 and below show the results of applying LED (152b) lighting and front lighting (21) respectively, separated by RGB channels.

[0091]

[0092] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 190 Cathode: approx. 100 Anode: approx. 2590 (47.37% change) 75 (75.00% change) [Green Channel] Separator: approx. 40 Cathode: approx. 20 Anode: approx. 520 (50.00% change) 15 (75.00% change) [Blue Channel] Separator: approx. 20 Cathode: approx. 15 Anode: approx. 155 (25.00% change) 0 (0.00% change)

[0093] <LED 조명(Red) / 전면 조명 (Red)>

[0094]

[0095] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 110 Cathode: approx. 30 Anode: approx. 1580 (72.73% change) 15 (50.00% change) [Green Channel] Separator: approx. 145 Cathode: approx. 105 Anode: approx. 2040 (27.59% change) 85 (80.95% change) [Blue Channel] Separator: approx. 70 Cathode: approx. 50 Anode: approx. 2020 (28.57% change) 30 (60.00% change)

[0096] <LED 조명(Red) / 전면 조명(Green)>

[0097]

[0098] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 90 Cathode: approx. 25 Anode: approx. 1065 (72.22% change) 15 (60.00% change) [Green Channel] Separator: approx. 45 Cathode: approx. 25 Anode: approx. 520 (44.44% change) 20 (80.00% change) [Blue Channel] Separator: approx. 140 Cathode: approx. 120 Anode: approx. 2520 (14.29% change) 95 (79.17% change)

[0099] <LED 조명(Red) / 전면 조명(Blue)>

[0100]

[0101] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 190 Cathode: approx. 140 Anode: approx. 2550 (26.32% change) 115 (82.14% change) [Green Channel] Separator: approx. 90 Cathode: approx. 30 Anode: approx. 1060 (66.67% change) 20 (66.67% change) [Blue Channel] Separator: approx. 50 Cathode: approx. 25 Anode: approx. 1825 (50.00% change) 7 (28.00% change)

[0102] <LED 조명(Green) / 전면 조명(Red)>

[0103]

[0104] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 55 Cathode: approx. 20 Anode: approx. 1035 (63.64% change) 10 (50.00% change) [Green Channel] Separator: approx. 195 Cathode: approx. 125 Anode: approx. 2070 (35.90% change) 105 (84.00% change) [Blue Channel] Separator: approx. 100 Cathode: approx. 65 Anode: approx. 2035 (35.00% change) 45 (69.23% change)

[0105] <LED 조명(Green) / 전면 조명(Green)>

[0106]

[0107] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 40 Cathode: approx. 15 Anode: approx. 1025 (62.50% change) 5 (33.33% change) [Green Channel] Separator: approx. 80 Cathode: approx. 35 Anode: approx. 1045 (56.25% change) 25 (71.43% change) [Blue Channel] Separator: approx. 200 Cathode: approx. 160 Anode: approx. 4040 (20.00% change) 120 (75.00% change)

[0108] <LED 조명(Green) / 전면 조명(Blue )>

[0109]

[0110] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 145 Cathode: approx. 110 Anode: approx. 2035 (24.14% change) 90 (81.82% change) [Green Channel] Separator: approx. 70 Cathode: approx. 30 Anode: approx. 1040 (57.14% change) 20 (66.67% change) [Blue Channel] Separator: approx. 70 Cathode: approx. 25 Anode: approx. 2045 (64.29% change) 5 (20.00% change)

[0111] <LED 조명(Blue) / 전면 조명(Red)>

[0112]

[0113] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 40 Cathode: approx. 20 Anode: approx. 1020 (50.00% change) 10 (50.00% change) [Green Channel] Separator: approx. 150 Cathode: approx. 100 Anode: approx. 2050 (33.33% change) 80 (80.00% change) [Blue Channel] Separator: approx. 110 Cathode: approx. 60 Anode: approx. 2050 (45.45% change) 40 (66.67% change)

[0114] <LED 조명(Blue) / 전면 조명(Green)>

[0115]

[0116] Gray Value (GV) Separator-Cathode GV Deviation Cathode-Anode GV Deviation [Red Channel] Separator: approx. 30 Cathode: approx. 12 Anode: approx. 818 (60.00% change) 4 (33.33% change) [Green Channel] Separator: approx. 70 Cathode: approx. 30 Anode: approx. 1040 (57.14% change) 20 (66.67% change) [Blue Channel] Separator: approx. 185 Cathode: approx. 130 Anode: approx. 3055 (29.73% change) 100 (76.92% change)

[0117] <LED 조명(Blue) / 전면 조명(Blue)>

[0118]

[0119] Through the above experiment, when a cell gripper (15b) with a light guide plate (151b) applied according to one embodiment of the present invention is applied, the gap between the separator (11) and the cathode (13), and between the cathode (13) and the anode (12), can be clearly and precisely verified. In particular, the light guide plate (151b)-based cell gripper (15b) of the present invention exhibits excellent performance even in various lighting environments, and can improve image quality by optimizing the color combination of the LED (152b) and the front lighting (21). In addition, by selecting and analyzing specific channels of the RGB image, the presence or absence of a gap can be inspected more clearly, enabling a more precise quality inspection of the stack structure. These results demonstrate that applying a light guide plate (151b)-based cell gripper (15b) is essential in the gap verification process and allows for flexible response to changing working environments through various color combinations.

[0120] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without altering its technical concept or essential features. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A step of fixing the separator to the stack table in a folded state; A step of fixing the first electrode and the second electrode to the first and second pick-and-place units and combining them with the separator; A step in which a cell gripper made of a light guide plate material grips a stack cell combined with the separator; and The step of transferring the stack cell to the stack table and performing a stack inspection through stack vision imaging, Secondary battery stack vision inspection method.

2. In Paragraph 1, The step of fixing the first electrode and the second electrode to the first and second pick-and-place units and combining them with the separator is, The first electrode is an anode and the second electrode is a cathode, and the first electrode, the separator, and the second electrode are joined in that order based on the spread separator. Secondary battery stack vision inspection method.

3. In Paragraph 2, The above cathode is configured to have a greater overall width and overall length than the anode, Secondary battery stack vision inspection method.

4. In Paragraph 1, The step of the cell gripper gripping the stack cell combined with the separator is A step in which an upper cell gripper enters the upper part of the stack cell; A step in which a lower cell gripper enters the upper part of the stack cell; and The above upper cell gripper and lower cell gripper include the step of gripping the stack cell. Secondary battery stack vision inspection method.

5. In Paragraph 4, After the stack cell is gripped, the method further includes the step of the first and second pick-and-place units breaking the fixed state and returning to their original positions. Secondary battery stack vision inspection method.

6. In Paragraph 4, The step of transferring the stack cell to the stack table and performing a stack inspection through stack vision imaging is: A step in which the upper cell gripper that has entered the upper part of the stack cell moves backward and exits; A step of lowering a cell pressing jig onto the upper part of the stack cell to fix the stack cell; and A step comprising emitting light from the light guide plate of the lower cell gripper, Secondary battery stack vision inspection method.

7. In Paragraph 6, The lower cell gripper of the light guide plate material is composed of acrylic material. Secondary battery stack vision inspection method.

8. In Paragraph 6, The lower cell gripper of the above light guide plate material is used as a light source with an LED attached to its side. Secondary battery stack vision inspection method.

9. In Paragraph 1, The step of transferring the stack cell to the stack table and performing a stack inspection through stack vision imaging is: Verifying stack quality by measuring the gap between the cathode, separator, and anode of the stack cell. Secondary battery stack vision inspection method.

10. A stack table on which a stack cell combined with a separator is seated, A cell gripper including a light guide plate that grips the stack cell and transfers it to the stack table, A vision camera for vision imaging to inspect the above stack cell and A cell pressing jig comprising a cell that descends onto the upper part of the stack cell and fixes the stack cell during the above vision imaging, Secondary battery stack vision imaging system.

11. In Paragraph 10, The cell gripper mentioned above is, An upper cell gripper entering the upper part of the stack cell and It includes a lower cell gripper that enters the lower part of the stack cell, and The light guide plate is included in the lower cell gripper, Secondary battery stack vision imaging system.

12. In Paragraph 11, The light guide plate included in the lower cell gripper is composed of an acrylic material. Secondary battery stack vision imaging system.

13. In Paragraph 11, The lower cell gripper above includes an LED attached to the side and operating as a light source emitting light from the bottom of the stack cell, Secondary battery stack vision imaging system.

14. In Paragraph 13, Further including a front light positioned on the upper front of the stack cell for vision imaging of the vision camera, providing a predetermined amount of light and color temperature. Secondary battery stack vision imaging system.

15. In Paragraph 14, The colors of the above LED and the above front light are each selected as one of the RGB colors and emit light. Secondary battery stack vision imaging system.

16. In Paragraph 14, The colors of the above LED and the above front light are selected to be the same color and emit light, Secondary battery stack vision imaging system.

17. In Paragraph 11, The cell pressing jig above lowers to fix the stack cell after the upper cell gripper, which has entered the upper part of the stack cell, has retracted and exited. Secondary battery stack vision imaging system.

Images