>FIGS. 5A and 5B are repeated. The points P_1R(x,y), P_2R(x,y), P_3R(x,y), and P_4R(x,y) extracted from the right boundary may be represented at positions that are spaced apart at intervals of a predetermined angle (the angle of rotation of the secondary battery 1000) from the central axis.

Referring to FIG. 5D, since the point extraction process is completed by rotating the secondary battery 1000 by only 180 degrees, the computing part may generate three-dimensional data for a full 360-degree angle.

As explained above, in the present disclosure, the three-dimensional scanning of the secondary battery 1000 may be performed by creating a three-dimensional model using points extracted from a projection image. In this instance, points extracted using a single camera 300 can be merged into 3D data, thereby simplifying the equipment.

While the present embodiment has been described with an example in which three-dimensional data is created by rotating the secondary battery 1000 by 180 degrees, it may be modified and practiced in such a manner that three-dimensional data is created by rotating the secondary battery 1000 by 360 degrees or more.

Moreover, although the present embodiment has been described with an example in which a single cylindrical battery is captured, this is merely an example and the scanning apparatus 1 according to the present disclosure may be modified and practiced in such a manner that varying numbers of secondary batteries 1000 are simultaneously rotated and simultaneously captured.

The computing part may perform appearance defect detection by using three-dimensional information generated of the secondary battery 1000.

Hereinafter, a 3D scanning apparatus 1 for a cylindrical secondary battery 1000 according to a second embodiment of the present disclosure will be described with reference to FIGS. 6 to 8. The 3D scanning apparatus 1 according to this embodiment may include the same components as the foregoing first embodiment, and it is to be noted that descriptions of the same components will be omitted in order to avoid redundant explanation, and only the differences will be described in detail.

If there is no coaxial lighting depending on the geometry of the cylindrical shape, images may be acquired in a symmetrical fashion, making it impossible to find out which direction the secondary battery 1000 is turned toward. Moreover, even with a misalignment (ex. yawing) of the secondary battery 1000, points along the boundary the side surface may look no different on a projection image. Accordingly, the second embodiment is implemented in such a way as to detect a misalignment of the secondary battery 1000 and create and correct (calibrate) a 3D model based on the detected turn.

FIG. 6 is a perspective view of a 3D scanning apparatus 1 for a cylindrical secondary battery 1000 according to a second embodiment of the present disclosure.

Referring to FIG. 6, the 3D scanning apparatus 1 for the cylindrical secondary battery 1000 according to the second embodiment of the present disclosure may further include a mirror part 500 and a coaxial lighting part 400. The coaxial lighting part 400 may include a beam splitter and a lighting module.

The mirror part 500 may be provided in an area captured by the camera 300, and the camera 300 may acquire a projection image of the secondary battery 1000 which appears when it is reflected off the mirror part 500.

The coaxial lighting part 400 is configured to emit light toward the side of the secondary battery 1000 which is captured by the camera 300.

The controller is configured to control the coaxial lighting part 400, the rear lighting part 200, the camera 300, and the driving part. The controller may control the camera 300 to acquire an image when the coaxial lighting part 400 and the rear lighting part 200 simultaneously emit light toward the secondary battery 1000.

In the present embodiment, it is possible to extract boundary information acquired when light is emitted from behind the secondary battery 1000 and boundary information of one half of the side surface of the secondary battery 1000 facing the camera 300. The computing part may calculate displacement information if boundary points on the front half surface and the rear half surface are different, and three-dimensional model information may be corrected based on the calculated displacement information.

It should be noted that, while the present embodiment provides the mirror part 500 as an additional component, the mirror part may be omitted.

FIG. 7 is a view illustrating an example of an image acquired according to the second embodiment of the present disclosure.

Referring to FIG. 7, in the second embodiment, the edge of the front half surface (the surface facing the camera 300) of the secondary battery 1000 may be detected by using coaxial lighting.

Accordingly, in this embodiment, an image is acquired as light is emitted by using coaxial lighting. The computing part may extract points on the edge of upper and lower surfaces facing the camera 300 in the acquired image.

FIG. 8 is a view illustrating a concept of extracting points in the region I of FIG. 7 in order to compensate for a displacement according to the second embodiment.

Referring to FIG. 8, the computing part extracts a point Pe1 on a first edge which is closest to the camera 300 from among points identified by coaxial lighting. Also, the computing part extracts a point Pe2 on a second edge which is farthest from the camera 300 from among points identified by the rear lighting part 200. In this case, the point closest to or farthest from the camera 300 may be selected as a point on a boundary intersecting the transverse axis.

The computing part calculates how many degrees the secondary battery 1000 is misaligned toward the camera 300 by using pre-inputted information, i.e., the diameter of the upper or lower surface of the secondary battery 1000 and the distance between the first edge and the second edge. Based on misalignment angle of the secondary battery 1000, 3D data for the secondary battery 1000 explained in the first embodiment will be corrected.

Hereinafter, a 3D scanning method for a cylindrical secondary battery according to a third embodiment of the present disclosure will be described in detail with reference to FIG. 9.

FIG. 9 is a flowchart of a 3D scanning method for a cylindrical secondary battery according to a third embodiment of the present disclosure.

Referring to FIG. 9, the 3D scanning method for the cylindrical secondary battery according to the third embodiment of the present disclosure may include the step S110 of acquiring projection images while emitting light from behind the cylindrical secondary battery, the step S120 of extracting length information, outer diameter information, and side boundary information from the projection images, and the step S130 of creating a three-dimensional model of the secondary battery.

The step S110 of acquiring projection images while emitting light from behind the cylindrical secondary battery may be performed by emitting light from behind the secondary battery and acquiring images using a camera on the other side. This step may be repeatedly performed by rotating the secondary battery at a predetermined angle. That is, through this step, tens or hundreds of images of the secondary battery may be acquired.

The step S120 of extracting length information, outer diameter information, and side boundary information from the projection images corresponds to the step of obtaining length information, outer diameter information, and side boundary information of the secondary battery by extracting boundary points from the projection images. The projection images may be acquired while the secondary battery is fixed in the same position. Thus, a pixel size identified from the images based on pre-inputted reference values may match the actual size. Based on this, information on the length and outer diameter of the secondary battery may be extracted, and information on the boundary (two lines) around the side may be extracted.

The step S130 of creating a three-dimensional model of the secondary battery corresponds to the step of performing three-dimensional modeling based on the extracted length information, outer diameter information, and side boundary information. In this step, points are extracted as the cylindrical secondary battery is rotated, and therefore side boundary points extracted for each predetermined angle may be three-dimensionally reconstructed.

Hereinafter, a 3D scanning method for a cylindrical secondary battery according to a fourth embodiment of the present disclosure will be described in detail with reference to FIG. 10.

FIG. 10 is a flowchart of a 3D scanning method for a cylindrical secondary battery according to a fourth embodiment of the present disclosure.

In this embodiment, the term “projection image” may mean an image that is acquired when light is emitted from the front as well as from the back.

Referring to FIG. 10, the 3D scanning method for the cylindrical secondary battery according to the fourth embodiment of the present disclosure may include the step S210 of acquiring projection images while emitting light coaxially with the back of the cylindrical secondary battery and the camera, the step S220 of extracting length information, outer diameter information, and side boundary information from the projection images, the step S230 of calculating the angle of displacement of the secondary battery, and the step S240 of creating a three-dimensional model of the secondary battery. Here, the steps of extracting information and creating a three-dimensional model may be performed by a computing part including a processor.

The step S210 of acquiring projection images while emitting light coaxially with the back of the cylindrical secondary battery and the camera corresponds to the step of emitting light from the front and back of the secondary battery and acquiring images.

The step S220 of extracting length information, outer diameter information, and side boundary information corresponds to the step of extracting the coordinates of pixels on a boundary by processing the images. In this step, the edge of the upper or lower surface illuminated with light from the front of the secondary battery may be identified.

In particular, if the secondary battery is turned toward the camera, a point on the edge of the upper or lower surface illuminated with light from the front and a point on the edge of the upper or lower surface illuminated with light from the back may be identified simultaneously. In this instance, the computing part may extract a point on the edge which is farthest from the camera and a point on the edge which is closest to the camera and find information on the distance between the two points. However, these points may not be extracted unless the secondary battery is placed in the right position without displacement, and the distance information may be zero.

The step S230 of calculating the angle of displacement of the secondary battery is the step of calculating the amount of displacement of the secondary battery toward the camera by using the outer diameter information and distance information of the secondary battery.

The step S240 of creating a three-dimensional model of the secondary battery corresponds to the step of correcting a three-dimensional model of the side of the secondary battery based on the angle of displacement of the secondary battery. Through this step, the angle of displacement may be easily found even if the secondary battery is not placed in the right position toward the camera. Also, an accurate three-dimensional model may be created based on the angle of displacement of the secondary battery.

As explained above, a 3D scanning apparatus and 3D scanning method for a cylindrical secondary battery according to the present disclosure make it possible to reconstruct an accurate three-dimensional model of the cylindrical secondary battery by means of a simple construction with a single camera.

Hereinafter, a 3D scanning and appearance inspection apparatus for a secondary battery according to a fifth embodiment of the present disclosure will be described in detail with reference to FIGS. 11 to 16. The 3D scanning and appearance inspection apparatus according to this embodiment may include the same components as the foregoing embodiments, and it is to be noted that descriptions of the same components will be omitted in order to avoid redundant explanation, and only the differences will be described in detail.

FIG. 11 is a perspective view of a 3D scanning and appearance inspection apparatus for a cylindrical secondary battery according to a fifth embodiment of the present disclosure. FIG. 12 is a view illustrating a front lighting part according to the fifth embodiment of the present disclosure.

Referring to FIGS. 11 and 12, the 3D scanning and appearance inspection apparatus for the secondary battery according to the fifth embodiment of the present disclosure may include a front lighting part 600. The front lighting part 600 may be configured to emit light toward the secondary battery coaxially with the camera. The front lighting part 600 may include a beam splitter 620 and a front lighting module 610. The beam splitter may be provided at a position where the camera and the optical axis of the front lighting module 610 intersect.

The front lighting module 610 may include a plurality of lighting units 611, 612, . . . , 618. The plurality of lighting units may be sequentially provided along the lengthwise direction of the secondary battery. Each lighting unit may be made with a predetermined width. Also, each lighting unit 611, 612, . . . , 618 may be configured to be controlled independently by the controller. Although the front lighting module