KR102764956B1 - Photometric LED Light Guide Plate, photometric system including the LGP, and defect detection method using it - Google Patents

Abstract

The present invention relates to lighting for inspecting the surface of a product, and more specifically, to a photometric LED light guide plate, a photometric system including the same, and a defect judgment method using the same. To this end, the light guide plate (220) uniformly reflects light incident from a thickness surface in one plane; a first LED group (240) installed on one side of the light guide plate (220) to irradiate light to the thickness surface; a second LED group (250) installed on the other side of the light guide plate (220) to irradiate light to the thickness surface; a third LED group (260) installed on a third side of the light guide plate (220); a fourth LED group (270) installed on a fourth side of the light guide plate (220); a plurality of LEDs (230) arranged in the first LED group (240), the second LED group (250), the third LED group (260), and the fourth LED group (270) in the direction of the sides of the light guide plate (220); A photometric LED light guide plate is provided, which comprises a frame (210) that surrounds one side, the other side, the third side, and the fourth side of an edge of a light guide plate (220) and accommodates a first LED group (240), a second LED group (250), a third LED group (260), and a fourth LED group (270) inside; and wherein the first LED group (240), the second LED group (250), the third LED group (260), and the fourth LED group (270) sequentially emit light.

Description

{Photometric LED Light Guide Plate, photometric system including the LGP, and defect detection method using it}

The present invention relates to lighting for inspecting the surface of a product, and more specifically, to an LED light guide plate for photometric use, a photometric system including the same, and a defect determination method using the same.

Recently, as portable IT devices such as smartphones, tablet PCs, and laptops have become widespread, mass production of various electronic components inside them and quality inspections are being conducted in parallel. In particular, inspection of electronic components includes not only inspection of internal circuits but also surface inspection using cameras and lights as part of the quality inspection scope. The targets of surface inspection include scratches, dents, cracks, terminal deformation, or terminal shorts on the surface of electronic components.

In addition, due to the development of the battery industry, various secondary batteries are being developed and put into initial production. In order to reduce manufacturing defects in secondary batteries that are being mass-produced, preliminary quality inspections are being performed. Accordingly, ultra-high-speed inspection of electronic components or secondary batteries (hereinafter referred to as “subjects”) has become an indispensable element.

Fig. 1 is an example of a photometric system using conventional lighting. As shown in Fig. 1, a camera (10) is positioned at the top, and an inspection target subject (30) is positioned at the bottom. Then, light (20) is emitted diagonally from the upper side (photometric method). At this time, if there is an unevenness or a three-dimensional shape on the upper surface of the subject (30), a shadow (40) is generated. Then, the amount of light irradiated diagonally decreases as the distance increases, and the angular conditions of the characteristic parts (corners, vertices, etc.) of the subject change. Therefore, it was impossible to implement the same optical effect as the distance from the light source increased. As a result, when light was irradiated on a subject having an unevenness on the upper surface as shown in Fig. 1 using a photometric method, the accuracy of defect detection was not high.

1. Republic of Korea Patent Registration No. 10-2135472 (Non-Lambertian Surface Inspection System), 2. Republic of Korea Utility Model Registration No. 20-0297859 (Lighting device for surface inspection).

Accordingly, the present invention has been made to solve the above problems, and the problem to be solved by the present invention is to provide a photometric LED light guide plate capable of accurately detecting defects even in a wall or uneven subject by irradiating uniform parallel light from the upper surface of the subject, a photometric system including the same, and a defect judgment method using the same.

However, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

In order to achieve the above technical task, a photometric LED light guide plate is provided, characterized by including: a light guide plate (220) that uniformly reflects light incident from a thickness surface into one plane; a first LED group (240) that is installed on one side of the light guide plate (220) and irradiates light onto the thickness surface; a second LED group (250) that is installed on the other side of the light guide plate (220) and irradiates light onto the thickness surface; and a frame (210) that surrounds at least one side and the other side of an edge of the light guide plate (220) and accommodates the first LED group (240) and the second LED group (250) therein.

Additionally, the first LED group (240) and/or the second LED group (250) have multiple LEDs (230) arranged in the direction of the side of the light guide plate (220).

In addition, the light guide plate (220) is rectangular and further includes a first LED group (240) installed on a first side of the light guide plate (220); a second LED group (250) installed on a second side of the light guide plate (220); a third LED group (260) installed on a third side of the light guide plate (220); and a fourth LED group (270) installed on a fourth side of the light guide plate (220).

Additionally, the 1st, 2nd, 3rd, and 4th LED groups (240, 250, 260, 270) emit light sequentially.

The above-described object of the present invention can also be achieved by a photometric system including an LED light guide plate, which is characterized by including, as another embodiment, the LED light guide plate (200); a camera (10) positioned above the LED light guide plate (200) to photograph a subject (30) through the light guide plate (220) and to photograph an image whenever a plurality of LED groups sequentially blink; an image processing means for synthesizing a plurality of images output by the camera (10) to generate an integrated image (280); and a control unit for detecting a defect from the integrated image (280) and synchronizing the operations of the LED light guide plate (200) and the camera (10).

Additionally, the image is a RAW image or a JPG image for photometric purposes.

Additionally, the LED light guide plate (200) is oriented to uniformly reflect light toward the subject (30).

Additionally, the upper surface shape of the subject (30) has unevenness.

The purpose of the present invention as described above is, in another category, a defect judgment method using a photometric system including the aforementioned LED light guide plate, comprising: a step (S100) of arranging a subject (30) under an LED light guide plate (200); a step (S120) of having a camera (10) capture a first image of the subject (30) when a first LED group (240) of the LED light guide plate (200) emits light; a step (S140) of having a camera (10) capture a second image of the subject (30) when a second LED group (250) of the LED light guide plate (200) emits light; a step (S160) of having a camera (10) capture a third image of the subject (30) when a third LED group (260) of the LED light guide plate (200) emits light; The invention can also be achieved by a defect determination method using a photometric system including an LED light guide plate, characterized in that it includes a step (S180) in which a camera (10) captures a fourth image of a subject (30) when a fourth LED group (270) of an LED light guide plate (200) emits light; a step (S200) in which an image processing means synthesizes the first, second, third, and fourth images to generate an integrated image (280); a step (S220) in which a control unit detects a defect from the integrated image (280); and steps (S240, S260, S280) in which the control unit determines whether the subject (30) is defective based on the detected defect.

According to one embodiment of the present invention, the LED light guide plate can be configured slimly, thereby saving space in the overall photometric system.

In addition, even for subjects with uneven surfaces, steps, or external walls that create shadows, a leveled image can be obtained by irradiating uniform parallel light. This allows for the determination of surface roughness or unevenness of the subject as good quality.

However, the effects obtainable from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.
Figure 1 is an example of a photometric system using conventional lighting.
Figure 2 is a schematic diagram of a photometric system according to the present invention;
Figure 3 is a perspective view of an LED light guide plate (200) according to the present invention.
Figure 4 is an exploded perspective view of the LED light guide plate (200) shown in Figure 3.
Figure 5 is a flow chart showing a defect determination method using a photometric system according to the present invention.
FIG. 6a is an example of a first image captured by the photometric system of the present invention;
FIG. 6b is an example of a second image captured by the photometric system of the present invention.
FIG. 6c is an example of a third image captured by the photometric system of the present invention.
FIG. 6d is an example of a fourth image captured by the photometric system of the present invention.
Fig. 7 is an example of an integrated image generated by synthesizing the images of Figs. 6a to 6d.
Figure 8 is an example of a defect detected from an integrated image according to the present invention.
Fig. 9 is an example of an image captured by a photometric system using conventional lighting such as Fig. 1.
Fig. 10 is another example of a defect detected from an integrated image according to the present invention.
Fig. 11 is an example of a defect detected from an image captured by a photometric system using conventional lighting such as Fig. 1.
Fig. 12 is an example of a rough subject (30) most suitable for the photometric system according to the present invention.
Fig. 13 is an example of a defect detected from the integrated image (280) of the subject (30) shown in Fig. 12.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, since the description of the present invention is merely an embodiment for structural and functional explanation, the scope of the rights of the present invention should not be construed as being limited by the embodiments described in the text. That is, since the embodiments can be variously modified and can have various forms, the scope of the rights of the present invention should be understood to include equivalents that can realize the technical idea. In addition, the purpose or effect presented in the present invention does not mean that a specific embodiment must include all of them or only such effects, and therefore the scope of the rights of the present invention should not be understood as being limited thereby.

The meanings of terms described in the present invention should be understood as follows.

The terms "first", "second", etc. are intended to distinguish one component from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. When a component is referred to as being "connected" to another component, it should be understood that it may be directly connected to the other component, but there may also be another component in between. On the other hand, when a component is referred to as being "directly connected" to another component, it should be understood that there is no other component in between. Meanwhile, other expressions that describe the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to", should be interpreted in the same way.

A singular expression should be understood to include the plural expression unless the context clearly indicates otherwise, and the terms "comprises" or "have" should be understood to specify the presence of a stated feature, number, step, operation, component, part, or combination thereof, but not to exclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

All terms used herein, unless otherwise defined, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the contextual meaning of the relevant art, and shall not be interpreted as having an ideal or overly formal meaning unless explicitly defined in the present invention.

Composition of the example

Hereinafter, the configuration of a preferred embodiment will be described in detail with reference to the attached drawings. FIG. 2 is a schematic diagram of a photometric system according to the present invention, FIG. 3 is a perspective view of an LED light guide plate (200) according to the present invention, and FIG. 4 is an exploded perspective view of the LED light guide plate (200) illustrated in FIG. 3. As illustrated in FIG. 2, a camera (10) is positioned so as to face a subject (30) from above downward. The camera (10) photographs the subject (30) according to a control command from a control unit and outputs the image as a RAW image. This camera (10) is a digital camera or an industrial camera.

The LED light guide plate (200) is placed horizontally between the camera (10) and the subject (30), and is oriented so that light irradiated on the thickness surface is irradiated to the subject (30). The LED light guide plate (200) reflects light irradiated on the thickness surface as uniform parallel light.

The subject (30) can be an electronic component or a secondary battery, and may have a rough surface, a three-dimensional shape, steps, or a peripheral wall. This subject (30) is transported and placed at high speed through a conveyor belt or the like.

As shown in FIGS. 3 and 4, the light guide plate (220) is a rectangular transparent panel having first, second, third, and fourth sides, and is very thin compared to its width. The light guide plate (220) uniformly reflects light incident from the thickness surface toward the subject (30), thereby exhibiting the effect of surface light emission by parallel light. The light guide plate (220) is widely used in LCD panels, lighting, etc.

A first LED group (240) is arranged along the first side of the light guide plate (220) in the thickness plane. The first LED group (240) comprises a plurality of LEDs (230) arranged in 1 to 2 rows in the direction of the side of the light guide plate (220). This first LED group (240) irradiates light onto the thickness plane of the light guide plate (220).

A second LED group (250) is arranged along the second side of the light guide plate (220) in the thickness plane. The second LED group (250) comprises a plurality of LEDs (230) arranged in 1 to 2 rows in the direction of the side of the light guide plate (220). This second LED group (250) irradiates light onto the thickness plane of the light guide plate (220).

A third LED group (260) is arranged along the third side of the light guide plate (220) in the thickness plane. The third LED group (260) comprises a plurality of LEDs (230) arranged in 1 to 2 rows in the direction of the side of the light guide plate (220). This third LED group (260) irradiates light onto the thickness plane of the light guide plate (220).

A fourth LED group (270) is arranged along the thickness surface of the fourth side of the light guide plate (220). The fourth LED group (270) is composed of a plurality of LEDs (230) arranged in 1 to 2 rows in the direction of the side of the light guide plate (220). This fourth LED group (270) irradiates light onto the thickness surface of the light guide plate (220).

These 1st, 2nd, 3rd, and 4th LED groups (240, 250, 260, 270) sequentially light up (or blink) according to the control command of the control unit.

The frame (210) is made of metal or plastic, surrounds the first, second, third, and fourth edges of the light guide plate (220), and accommodates the first, second, third, and fourth LED groups (240, 250, 260, 270) inside.

The image processing means synthesizes the first, second, third, and fourth images output by the camera (10) to create a single integrated image (280). The image processing means may be an image processing program executable on a computer (e.g., Photometric Stereo Techiniques of Matrox, Photometric_Stereo of Falcon, SurfaceFX of Cognex) or a library.

The control unit detects defects from the integrated image (280) and synchronizes the operations of the LED light guide plate (200) and the camera (10). For this purpose, the control unit may be a computer having a CPU, a microcomputer, a programmable logic controller (PLC), etc.

Actions of the example

Hereinafter, the operation of a preferred embodiment will be described in detail with reference to the attached drawings. Fig. 5 is a flow chart showing a defect determination method using a photometric system according to the present invention. As shown in Fig. 5, first, the system is initialized, and a subject (30) is placed under an LED light guide plate (200) (S100).

At the same time that the first LED group (240) of the LED light guide plate (200) emits light, the camera (10) captures a first image of the subject (30) (S120).

Next, the second LED group (250) of the LED light guide plate (200) emits light and the camera (10) captures a second image of the subject (30) (S140).

Next, the third LED group (260) of the LED light guide plate (200) lights up and the camera (10) captures a third image of the subject (30) (S160).

Next, the fourth LED group (270) of the LED light guide plate (200) lights up and the camera (10) captures a fourth image of the subject (30) (S180). The captured first, second, third, and fourth images are transmitted to the control unit.

Next, the image processing means synthesizes the first, second, third, and fourth images to create an integrated image (280) (S200).

Next, the control unit detects a defect from the integrated image (280) (S220).

Next, the control unit determines whether the subject (30) is defective based on the detected defect. That is, it determines whether there is a defect (S240), and if there is a defect, the subject (30) is determined to be defective (S260), and if there is no defect, the subject (30) is determined to be good (S280).

The subject placement step (S100) to the judgment step (S280) are performed at a very high speed, and after the judged subject (30) is discharged, the same process is repeated for the next subject (30).

Test of the example

Hereinafter, test results of a preferred embodiment will be described in detail with reference to the attached drawings.

First, FIG. 6a is an example of a first image captured by the photometric system of the present invention, FIG. 6b is an example of a second image captured by the photometric system of the present invention, FIG. 6c is an example of a third image captured by the photometric system of the present invention, and FIG. 6d is an example of a fourth image captured by the photometric system of the present invention.

As shown in FIGS. 6a to 6d, the first, second, third, and fourth images are acquired by sequentially emitting light from the first, second, third, and fourth LED groups (240, 250, 260, and 270) on a subject (30) having unevenness or steps on the upper surface.

Figure 7 is an example of an integrated image generated by synthesizing the images of Figures 6a to 6d.

Fig. 8 is an example of a defect detected from an integrated image according to the present invention, and Fig. 9 is an example of an image captured by a photometric system using conventional lighting, such as Fig. 1. As can be seen from the contrast between Figs. 8 and 9, scratches and press marks are clearly visible in Fig. 8, whereas they are not clearly visible in the conventional inspection method, such as Fig. 9. The subject (30) may be judged as a good product in the conventional inspection method, such as Fig. 9, but is judged as a defective product in the present invention, such as Fig. 8.

Fig. 10 is another example of a defect detected from an integrated image according to the present invention, and Fig. 11 is an example of a defect detected from an image captured by a photometric system using conventional lighting such as Fig. 1. It can be seen that a defect is clearly shown in Fig. 10 according to the present invention, although the defect is blurry in Fig. 11. This proves that the system of the present invention has high accuracy.

Fig. 12 is an example of a rough subject (30) most suitable for the photometric system according to the present invention. As shown in Fig. 12, the upper surface of the subject (30) is surrounded by an inner wall (35), and a metal disk is positioned inside.

And, Fig. 13 is an example of a defect detected from the integrated image (280) of the subject (30) illustrated in Fig. 12. As illustrated in Fig. 13, due to the uniform and parallel surface light irradiated vertically from above, the upper surface of the subject (30) could be inspected without the influence of shading due to the height of the inner wall (35), and it could be determined that there was a defect (290).

The detailed description of the preferred embodiments of the present invention disclosed above has been provided to enable those skilled in the art to implement and practice the present invention. While the above has been described with reference to preferred embodiments of the present invention, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope of the present invention. For example, those skilled in the art can utilize each of the configurations described in the above-described embodiments in a manner that combines them. Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The present invention may be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention. Accordingly, the above detailed description should not be construed in all aspects as restrictive but rather as illustrative. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all changes coming within the equivalent scope of the present invention are intended to be embraced therein. The present invention is not intended to be limited to the embodiments set forth herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In addition, claims that do not have an explicit citation relationship in the claims may be combined to constitute an embodiment or may be included as a new claim by post-application amendment.

10 : Camera,
20 : Lighting,
30 : Subject,
35 : Inner wall,
40 : shade,
100 : Photometric System,
200 : LED light guide plate,
210 : Frame,
220 : Light guide plate,
230 : LED,
240: 1st LED group,
250: 2nd LED group,
260: Third LED group,
270: 4th LED group,
280: Integrated image,
290 : Defect.

Claims (9)

A light guide plate (220) that uniformly reflects light incident from a thickness surface onto a single plane;
A first LED group (240) installed on one side of the above light guide plate (220) and irradiating light onto the thickness surface;
A second LED group (250) installed on the other side of the light guide plate (220) and irradiating light onto the thickness surface; and
A photometric LED light guide plate (200) including a frame (210) that surrounds at least one side and the other side of the edge of the light guide plate (220) and accommodates the first LED group (240) and the second LED group (250) inside;
A camera (10) positioned above the LED light guide plate (200) to photograph a subject (30) through the light guide plate (220) and to photograph an image whenever a plurality of LED groups flash sequentially;
An image processing means for synthesizing multiple images output by the above camera (10) to create an integrated image (280); and
A photometric system including an LED light guide plate, characterized by including a control unit for detecting a defect from the integrated image (280) and synchronizing the operations of the LED light guide plate (200) and the camera (10). In paragraph 1,
A photometric system including an LED light guide plate, characterized in that the first LED group (240) and/or the second LED group (250) have a plurality of LEDs (230) arranged in the direction of the side of the light guide plate (220). In paragraph 1,
The above light guide plate (220) is square,
The first LED group (240) installed on the first side of the light guide plate (220);
The second LED group (250) installed on the second side of the light guide plate (220);
A third LED group (260) installed on the third side of the light guide plate (220); and
A photometric system including an LED light guide plate, characterized in that it further includes a fourth LED group (270) installed on the fourth side of the light guide plate (220). In the third paragraph,
A photometric system including an LED light guide plate, characterized in that the first, second, third, and fourth LED groups (240, 250, 260, and 270) emit light sequentially. delete In paragraph 1,
A photometric system including an LED light guide plate, characterized in that the image above is a RAW image or a JPG image. In paragraph 1,
A photometric system including an LED light guide plate, characterized in that the LED light guide plate (200) is oriented to uniformly reflect light toward the subject (30). In paragraph 1,
A photometric system including an LED light guide plate, characterized in that the upper surface shape of the above subject (30) has an uneven surface. ◈Claim 9 was abandoned upon payment of the registration fee.◈ In a defect determination method using a photometric system including an LED light guide plate according to Article 1,
Step (S100) of placing a subject (30) on the lower side of the LED light guide plate (200);
A step (S120) in which the camera (10) captures a first image of the subject (30) when the first LED group (240) of the LED light guide plate (200) emits light;
A step (S140) in which the camera (10) captures a second image of the subject (30) when the second LED group (250) of the LED light guide plate (200) emits light;
Step (S160) in which the camera (10) captures a third image of the subject (30) when the third LED group (260) of the LED light guide plate (200) emits light;
Step (S180) in which the camera (10) captures a fourth image of the subject (30) when the fourth LED group (270) of the LED light guide plate (200) emits light;
A step (S200) in which the image processing means synthesizes the first, second, third, and fourth images to create an integrated image (280);
Step (S220) in which the control unit detects a defect from the integrated image (280); and
A defect determination method using a photometric system including an LED light guide plate, characterized in that the control unit includes a step (S240, S260, S280) of determining whether the subject (30) is defective based on the detected defect.

Images