Foreign body detection equipment and detection methods

Abstract

Disclosed are a debris detection device and a debris detection method capable of easily detecting metal debris present on the surface of an inspection target by emitting electromagnetic waves having a wavelength in the far-infrared band toward the inspection target during a battery manufacturing process and then analyzing the characteristics of reflected waves from the surface of the inspection target by a thermal image recorder.

Description

Technical Field

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2020-0095886, filed in the Korean Intellectual Property Office on July 31, 2020, the entire contents of which are incorporated herein by reference. The present disclosure relates to a debris detection device and a debris detection method that can easily detect metal debris present on the surface of an inspection target during a battery manufacturing process. Background Art

[0002] Generally speaking, during the battery manufacturing process, metal debris may appear in the external mold processing (swaging, bead pressing, etc.). Metal debris can cause electrical short circuits, thereby leading to battery failure. Such metal debris needs to be removed in advance through processes such as visual inspection. Therefore, after the swaging and bead pressing processes, the upper part of the jelly roll wound by the electrode and the separator, and the micro metal particles on the upper mouth of the insulating layer for electrical isolation of the upper cover of the electrode should be eliminated through processes such as visual inspection.

[0003] However, when the diameter of metal debris is 100 μm or less, it is difficult to identify the metal debris unless a microscope with a large magnification is used. In addition, it may be difficult to distinguish between metal debris and simple non-metallic dust.

[0004] An apparatus for detecting debris during a battery manufacturing process as described above is disclosed in Korean Patent Application Publication No. 10-2011-0029011 (published on March 22, 2011) and the like.

[0005] A related art debris detection device determines whether debris exists in a battery (hereinafter, referred to as an "inspection target") by applying a light scattering method to the surface of a battery case.

[0006] Specifically, conventional debris detection devices detect debris by illuminating an inspection target with direct light at a preset angle of incidence. When the reflected light's angle of incidence differs from the incident angle, the device interprets this as diffuse reflection due to the debris. This method has the advantage of allowing the sensor to be mounted at a predetermined angle, simplifying the structure of the debris detection device.

[0007] However, according to the related art debris detection apparatus, when the surface of the inspection target is rough or curved, light may be diffusely reflected at an angle different from an incident angle, which may cause an error in detecting debris. Summary of the Invention

[0008] Technical issues

[0009] Embodiments of the present disclosure are directed to providing a debris detection device and a debris detection method capable of easily detecting metal debris present on the surface of an inspection target by emitting electromagnetic waves having a wavelength in the far-infrared band toward the inspection target during a battery manufacturing process and then analyzing the characteristics of reflected waves from the surface of the inspection target by a thermal image recorder.

[0010] Technical Solution

[0011] To achieve the above-mentioned objectives, a debris detection device according to the present disclosure may include: an infrared emitting unit configured to emit infrared rays toward an inspection target; an optical unit configured to amplify an infrared signal reflected from metal debris present on the surface of the inspection target or to filter the infrared signal to obtain a desired signal; and a thermal image recorder configured to detect whether metal debris exists on the surface of the inspection target and the size and position of the metal debris through the amplified infrared signal.

[0012] In this case, the infrared emitting unit may emit electromagnetic waves having low energy in a far infrared band (7 μm to 14 μm) and maximize a reflection signal from metal chips without significantly increasing the temperature of the inspection target.

[0013] Furthermore, the infrared emitting unit may be disposed above the inspection target on the central axis while being spaced apart from the inspection target, and the optical unit and the thermal image recorder may be sequentially disposed above the infrared emitting unit on the central axis while being spaced apart from the infrared emitting unit.

[0014] In addition, the infrared emitting unit may further include a through hole formed along the central axis, and the infrared signal reflected from the surface of the inspection target may reach the optical unit and the thermal image recorder through the through hole.

[0015] Furthermore, the through hole may be formed to be equal to or larger than the diameter of the inspection target.

[0016] Furthermore, the optical unit may selectively include any one of a polarizing plate, a wave plate, and a bandpass filter.

[0017] Furthermore, the thermal image recorder may include a lens and a focal plane array (FPA) including a sensor array for detecting infrared signals, and record spatial positions of the infrared signals.

[0018] Furthermore, a debris detection method using the debris detection device may include the following steps:

[0019] Emitting far-infrared rays in the 7μm to 14μm band toward the inspection target;

[0020] An infrared signal reflected from metal debris present on the surface of the inspection target is amplified by an optical unit or the infrared signal is filtered to obtain a desired signal; and a spatial position is recorded by the infrared signal passing through the optical unit, and whether metal debris exists on the surface of the inspection target and the size and position of the metal debris are detected.

[0021] Beneficial effects

[0022] The debris detection device according to the present disclosure having the above configuration is capable of specifying metal debris present on the surface of the inspection target and the size and position of the metal debris by emitting electromagnetic waves in the far-infrared band toward the inspection target and then analyzing the characteristics of the reflected waves from the surface of the inspection target through a thermal image recorder.

[0023] In such a case, the infrared emitting unit uses light reflected when metal chips are detected, and thus a low power that hardly increases the temperature of the inspection target is used when selecting a light source for emitting far-infrared rays.

[0024] Furthermore, since a light source having low power is used, a signal due to metal chips can be generated, but the temperature around the inspection target does not increase, which can improve the resolution of metal chip detection.

[0025] Unlike the technology used by existing visible optical systems to identify metal particles through reflective imaging caused by scattering of fine particles in the visible light region, the corresponding technology is a method of increasing resolution by applying a tiny light source (heat source) in the long-wavelength infrared region to detect and image the reflected light of metal particles using the characteristic of metals having high reflectivity in the long-wavelength region compared to the short-wavelength region. Through the imaging in the infrared region described in the present invention, it is possible to separate other foreign matter such as powders or fine particles of organic / inorganic components that have fine particle diameters similar to foreign metal particles and have insulating properties, which are difficult to distinguish using existing visual methods, and it is possible to ensure the resolution capable of identifying and detecting metal particles present on materials with roughness that causes diffuse reflection or scattering in the visible light region.

[0026] Unlike existing methods that distinguish objects with different emissivity values ​​by causing a temperature rise by applying a specific amount of energy to the target to heat it, the corresponding technology is a method of selectively detecting reflected light using the high reflective properties of metal by allowing a light source to be incident in a tiny infrared region. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic side view illustrating a debris detection device according to the present disclosure.

[0028] Figure 2is a flow chart illustrating a debris detection process using the debris detection device according to the present disclosure.

[0029] Figure 3 and Figure 4 are experimental result data obtained by comparing the performance of the debris detection device according to the present disclosure. Figure 5 is a graph illustrating differences in thermal image signal sensitivity according to the size of metal chips detected by the chip detection device according to the present disclosure.

[0030] Description of Reference Numerals

[0031] 10: Inspection target 11: Battery tank

[0032] 13: monomer 15: insulator

[0033] P: Metal debris 100: Debris detection device

[0034] 110: Infrared emission unit 111: Through hole

[0035] 120: Optical unit 130: Thermal image recorder DETAILED DESCRIPTION

[0036] Hereinafter, the configuration and operation of certain embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0037] Note that when reference numerals are assigned to components in the drawings, the same reference numerals denote the same components in all drawings even in case that the components are illustrated in different drawings.

[0038] Figure 1 is a schematic side view illustrating a debris detection device 100 according to the present disclosure.

[0039] refer to Figure 1 The debris detection device 100 according to a preferred embodiment of the present disclosure may include an infrared emission unit 110 , an optical unit 120 and a thermal image recorder 130 .

[0040] The configuration of the present disclosure will be described in detail as follows.

[0041] First, the inspection target 10 may include: a cylindrical battery can 11, which constitutes the exterior of the battery; a cell 13, which is housed inside the battery can 11 and rolled into a jelly roll shape; and a non-woven fabric insulator 15, which is laminated on the upper surface of the cell 13 to prevent short circuits caused by metal debris P. Hereinafter, in the present disclosure, an example of a case where the presence of metal debris P on the upper surface of the insulator 15 of the inspection target 10 is inspected using the debris detection device 100 will be described. Of course, the present disclosure is not limited thereto.

[0042] The infrared emitting unit 110 may emit infrared rays toward the inspection target 10. The infrared emitting unit 110 may be configured as an emitter having appropriate energy enough to hardly heat the surface of the inspection target 10.

[0043] Specifically, the infrared emitting unit 110 may emit electromagnetic waves having low energy in a far infrared band of 7 μm to 14 μm sufficient to cause infrared reflection from metal debris P present on the surface of the inspection target 10 .

[0044] The far infrared rays emitted from the infrared emission unit 110 are electromagnetic waves emitted by a general object at room temperature, and the infrared emission unit 110 may be easily implemented without a special light source.

[0045] That is, the metal chips P have a high far-infrared reflection characteristic. Therefore, the infrared signal reflected by the metal chips P can be prominently displayed only by a heating source (infrared emitting unit) having a low temperature (about 36.5° C.) generated in a human hand and by a thermal image recorder 130 to be described below.

[0046] In other words, the far infrared rays (7 μm to 14 μm) emitted from the infrared emitting unit 110 can maximize the infrared reflection signal from the metal chips P without significantly increasing the temperature of the inspection target 10. Therefore, the thermal image recorder 130 can have a resolution sufficient to accurately specify even metal chips P with a size of several tens of μm.

[0047] When the temperature of the surface of the inspection target 10 is excessively increased by the infrared rays emitted from the infrared emitting unit 110, the temperature of the surface of the inspection target 10 is increased, and thus the infrared rays are emitted from the inspection target 10 itself. In such a case, the infrared rays emitted from the inspection target 10 itself may be difficult to distinguish from the infrared signals reflected from the metal chips P because they are mixed with each other. Therefore, it is preferable to use an infrared emitter with appropriate energy (for example, a human hand, an organic material with appropriate temperature and infrared emissivity, a polymer, etc.) as the infrared emitting unit 110.

[0048] The infrared emitting unit 110 may be disposed above the inspection target 10 on the central axis while being spaced apart from the inspection target 10. In addition, the optical unit 120 and the thermal image recorder 130 may be sequentially disposed above the infrared emitting unit 110 on the same central axis while being spaced apart from the infrared emitting unit 110.

[0049] In this case, the infrared emitting unit 110 may have a through hole 111 formed along a vertical central axis. The through hole 111 may allow an infrared signal reflected from the surface of the inspection target 10 to easily reach the optical unit 120 and the thermal image recorder 130 to be described below through the through hole of the infrared emitting unit 110. Preferably, the through hole 111 may be formed to be equal to or larger than the diameter of the inspection target 10.

[0050] The optical unit 120 can amplify infrared signals reflected from metal debris P on the surface of the inspection target 10 by optical effects or filter the infrared signals to obtain desired signals. As such an optical unit 120, a polarizing plate, a wave plate, a bandpass filter, etc. can be selectively applied.

[0051] The thermal image recorder 130 may detect whether metal chips P exist on the surface of the inspection target 10 through the infrared signal amplified by the optical unit 120 .

[0052] In such a case, the thermal image recorder 130 may include a thermal imaging camera, a computer, etc. Additionally, the thermal image recorder 130 may include a close-up lens to enhance detection capabilities by magnifying the image on the thermal image recorder 130 .

[0053] Such a thermal image recorder 130 can not only determine whether metal chips P exist on the inspection target 10 but also detect the size and position of the metal chips P through an array sensor (not shown) of a thermal imaging camera.

[0054] That is, the thermal image recorder 130 may include a lens and a focal plane array (FPA) including a sensor array for detecting infrared signals, thereby accurately recording spatial positions of the infrared signals.

[0055] Specifically, the array sensor of the thermal image recorder 130 is arranged at the same angle on the same central axis as the infrared emitting unit 110. That is, since the present invention does not use a method for comparing incident angles and reflection angles, it is not affected by the curvature or surface roughness of the surface of the inspection target 10.

[0056] Forms of the Invention

[0057] Next, a chip detection method using the chip detection device 100 according to the present disclosure having the above configuration will be described.

[0058] refer to Figure 2, the infrared emitting unit 110 emits far infrared rays in a wavelength band of 7 μm to 14 μm toward the inspection target 10 (S1). In this case, the infrared emitting unit 110 can maximize the reflection signal from the metal debris P present on the surface of the inspection target 10 without significantly increasing the temperature of the inspection target 10.

[0059] The infrared signal reflected from the metal chips P may be amplified by the optical unit 120 or may be filtered to obtain a desired signal ( S2 ).

[0060] Then, the thermal image recorder 130 may record a spatial position through the infrared signal passing through the optical unit 120 and detect whether metal chips P exist on the surface of the inspection target 10 and the size and position of the metal chips P ( S3 ).

[0061] refer to Figure 3 , after simulating metal debris P on the upper surface of the insulator 15 in the inspection target 10 by using aluminum powder (<100μm), the case (a) of applying the infrared emitting unit 110 of the present disclosure and the case (b) of applying a halogen lamp (right) as a heating source to be compared were implemented and compared and observed by the thermal image recorder 130.

[0062] Results, such as Figure 3 As shown in the figure, it can be seen that the case (a) of applying the infrared emitting unit 110 of the present disclosure can improve the detection resolution of the metal debris P by detecting only the reflection signal from the metal debris P without heating the peripheral portion of the inspection target 10. Due to the higher infrared reflectivity compared to the top cover insulator 15 made of non-woven fabric made of polybutylene terephthalate, the metal debris P falling on the upper surface of the insulator 15 of the inspection target 10 can be easily observed.

[0063] In addition, if Figure 4 As shown, the measurement results (yellow image portion) of the thermal image recorder 130 and the measurement results (black and white image portion) of the optical microscope (x100) are compared with each other. In this case, a human hand is used as a heating source, and contaminants in the form of particles (individual particles with a diameter of 20 μm or more) and contaminants in the form of fibers (particles smaller than 10 μm aggregated in fibers) are compared.

[0064] In this case, the position of the metal debris P on the fiber is actually observed by the optical microscope, and the measurement result of the thermal image recorder 130 indicates a state in which a thermal image signal is actually captured at the position of the metal debris P confirmed by the optical microscope.

[0065] As a result, it can be seen that the thermal image recorder 130 according to the present disclosure can improve the detection resolution of pollutants.

[0066] In addition, if Figure 5 As illustrated, a difference in thermal image signal sensitivity is examined according to the size of metal chips P. In this case, a human hand is used as a heating source.

[0067] As a result, it can be seen that the metal debris P having a size of 24.64 μm has a size close to the resolution limit of the thermal imaging camera of the thermal image recorder 130 and is not clearly distinguished from the noise.

[0068] That is, when the size of the metal debris P is at least 30 μm or larger, it can be distinguished from noise. In addition, since the infrared signal itself is small, it is judged that there is a difference in resolution only when a close-up lens is used.

[0069] In this case, when the thermal imaging camera constituting the thermal image recorder 130 has a high resolution, the measurable size of the metal chips P may be less than 30 μm.

[0070] Although the present disclosure has been illustrated and described with reference to specific embodiments, the present disclosure is not limited to the above embodiments, and various modifications and corrections can be made without departing from the technical spirit of the present disclosure.

Claims

1. A debris detection device, comprising: an infrared emitting unit configured to emit infrared rays toward an inspection target; an optical unit configured to amplify infrared signals reflected from metal debris present on the surface of the inspection target or to filter the infrared signals to obtain a desired signal; as well as a thermal image recorder configured to detect whether the metal debris exists on the surface of the inspection target and the size and position of the metal debris through the amplified infrared signal; The infrared emitting unit emits electromagnetic waves with low energy in a far infrared band of 7 μm to 14 μm, and maximizes a reflection signal from the metal debris without significantly increasing a temperature of the inspection target.

2. The debris detection device according to claim 1, wherein: The infrared emitting unit is arranged above the inspection target on the central axis while being spaced apart from the inspection target, and The optical unit and the thermal image recorder are sequentially arranged above the infrared emitting unit on the central axis while being spaced apart from the infrared emitting unit.

3. The debris detection device according to claim 2, wherein: The infrared emitting unit further includes a through hole formed along the central axis, and The infrared signal reflected from the surface of the inspection target reaches the optical unit and the thermal image recorder through the through hole.

4. The debris detection device according to claim 3, wherein: The through hole is formed to be equal to or larger than a diameter of the inspection target.

5. The debris detection device according to claim 1, wherein: The optical unit selectively includes any one of a polarizing plate, a wave plate, and a bandpass filter. The debris detection device according to claim 1 , wherein: The thermal image recorder includes a lens and a focal plane array including a sensor array for detecting the infrared signal, and records the spatial position of the infrared signal.

7. A debris detection method using the debris detection device according to any one of claims 1 to 6, the debris detection method comprising the following steps: Emitting far-infrared rays in the 7μm to 14μm band toward the inspection target; amplifying an infrared signal reflected from metal debris present on the surface of the inspection target by an optical unit or filtering the infrared signal to obtain a desired signal; as well as The spatial position is recorded by the infrared signal passing through the optical unit, and whether the metal debris exists on the surface of the inspection target and the size and position of the metal debris are detected.

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