Ultra-wide view angle imaging device and manufacturing method thereof

Abstract

To provide an ultra-wide viewing angle imaging apparatus capable of easily and satisfactorily synthesizing images photographed by respective image acquisition parts without performing complicated image processing, achieving the miniaturization of a system and acquiring a high-quality ultra-wide angle image, and to provide a method for manufacturing the imaging apparatus.SOLUTION: The imaging device includes a substrate 10 having an outer shape of a polyhedron or a part of a polyhedron (hereinafter referred to as a polyhedron or the like), a pixel area (5) in which a plurality of imaging pixels are arranged on an outer surface of each surface of the substrate 10, and an element lens 4 disposed for each surface (each imaging surface 3) so as to form a subject image on the pixel area (5).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for acquiring images with an extremely wide field of view (angle of view), such as a 360-degree panoramic image, and more particularly to an ultra-wide field of view imaging device in which multiple lenses are arranged around the periphery of the imaging device, and a method for manufacturing the same. [Background technology]

[0002] As imaging methods for acquiring ultra-wide-field images such as 360-degree panoramic images, various imaging technologies have been proposed so far, such as a method using a lens with an extremely wide angle of view, such as a fisheye lens, and a single image sensor (see, for example, Patent Document 1 below), and a multi-lens method that combines images obtained by using multiple cameras to capture images in different directions (see, for example, Patent Document 2 below). In the above-mentioned multi-camera system using multiple cameras, various omnidirectional imaging systems have been reported, ranging from highly portable systems equipped with two small cameras to systems with at least several cameras arranged on the circumference or on each face of a polyhedron. In particular, since the use of multiple cameras makes it possible to suppress image distortion and increase the number of pixels, imaging devices for acquiring high-quality ultra-wide-field images have been put to practical use, as shown in Non-Patent Document 1 below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-315380 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-250193 [Non-patent literature]

[0004] [Non-Patent Document 1] "Insta360 TITAN - Professional 360° VR 3D Camera with 11K Capture" (Action Camera 360° Camera - Insta360 Official Website)<URL:https: / / www.bing.com / aclick?ld> Summary of the Invention [Problem to be solved by the invention]

[0005] However, the imaging method using a fisheye lens or the like described in Patent Document 1 can capture ultra-wide-angle images simply by attaching a fisheye lens to a conventional camera, but it is not suitable for achieving high image quality because it causes significant distortion at the periphery of the image. Furthermore, the image systems using multiple cameras described in Patent Document 2 and Non-Patent Document 1 have the following problems. That is, when multiple cameras are arranged facing different directions, it is difficult to align them at the pixel level, and therefore cumbersome image correction processing is required to correct misalignment of the composite image, etc. Furthermore, if there is an external impact or a slight misalignment in the mechanism supporting the cameras, it becomes necessary to further align the images captured by each camera.

[0006] Furthermore, each camera needs to be positioned facing a different direction, but generally each camera is packaged with an image sensor and optical system built in, so the image sensors cannot be arranged densely. In addition, the system becomes larger because it is necessary to prevent interference between adjacent cameras.

[0007] The present invention aims to provide an ultra-wide viewing angle imaging device capable of acquiring high-quality ultra-wide-angle images, which can easily and effectively combine images captured by each image acquisition unit without any complicated image processing and can also achieve a compact system, and a method for manufacturing the same. [Means for solving the problem]

[0008] The ultra-wide viewing angle imaging device of the present invention comprises: a substrate having an outer shape that is a polyhedron or a portion of a polyhedron; a pixel area in which a plurality of imaging pixels are arranged on each outer surface of the substrate; element lenses arranged on each of the surfaces so as to form an image of a subject on a pixel area formed on the outer surface of each of the surfaces; The polyhedron or a part of the polyhedron is characterized in that, when unfolded, the faces are arranged closely together on a single plane. Here, the "close proximity" does not matter whether the surfaces are continuous with each other or are separated from each other. In this case, it is preferable that the surfaces are formed from the same material.

[0009] It is also preferable that the polyhedron or a portion of the polyhedron has, in an unfolded state, each of the faces be a continuous body on one plane. The substrate is preferably made of flexible plastic, and in this case, the substrate is preferably made of film-like plastic.

[0010] It is also preferable that the pixel area is formed over the entire outer surface of each side of the substrate, and in this case, the pixel area is preferably in the shape of a solid of revolution. It is also preferable that the angle of view of each surface of the substrate is set to an angle equal to or larger than the angle between adjacent surfaces.

[0011] On the other hand, the method for manufacturing an ultra-wide viewing angle imaging device of the present invention includes the steps of: A first step of cutting a shape corresponding to a developed figure of a substrate having an outline of a polyhedron or a part of a polyhedron from a flexible plastic material; a second step of forming a pixel area in which a plurality of pixels, each including a TFT, a pixel circuit, and wiring, are arranged at a position corresponding to the front surface side of each surface of the developed figure, and disposing a photoelectric conversion film on the pixel area; a third step of bending the substrate having a shape corresponding to the developed figure at predetermined positions to form the polyhedron or a three-dimensional shape that will become a part of the polyhedron; a fourth step of arranging element lenses on each of the surfaces so that a subject image is formed on a pixel area consisting of a plurality of imaging pixels formed on the outer surface of each of the surfaces; Of these four steps, one step of the first group of steps consisting of the first step and the second step is carried out first and the other step is carried out afterwards, and then one step of the second group of steps consisting of the third step and the fourth step is carried out first and the other step is carried out afterwards. Here, when a substrate having a shape corresponding to the unfolded figure is bent at a predetermined position to form a three-dimensional shape that will become the polyhedron or a part of the polyhedron, it is preferable to attach the substrate to a base having the same shape as the polyhedron or a part of the polyhedron. [Effects of the Invention]

[0012] According to the ultra-wide viewing angle imaging device and its manufacturing method of the present invention, a polyhedron having pixel areas formed on each surface, or a three-dimensional shape consisting of a part of a polyhedron, is first formed in its developed shape on a planar device, and then the device is folded at a predetermined position to form the three-dimensional shape that becomes the polyhedron or part of the polyhedron. Therefore, when a polyhedron or a three-dimensional shape that is a part of a polyhedron is formed, it is easy to accurately align adjacent imaging surfaces. Note that this also means that even in cases where each face of the developed figure of the device is cut and attached to a corresponding face of a base that has the same shape as the polyhedron or part of the polyhedron, it is possible to accurately cut the device along the boundaries between the faces of the developed figure, making it easier to accurately align adjacent faces than with conventional techniques without requiring complicated image correction processing.

[0013] Furthermore, since wiring can be drawn out from the spaces between each surface and from the back surface, it is easy to miniaturize the system. Therefore, the ultra-wide-angle imaging device and its manufacturing method of the present invention can easily and effectively combine images captured by each image capture unit without any unevenness in characteristics without any positional misalignment, without requiring complicated image processing, and can also achieve a compact system.Furthermore, it is possible to capture high-quality ultra-wide-angle images. If each of the above-mentioned surfaces is formed from the same material, the variation in device characteristics in the pixel area of ​​each surface can be reduced compared to the conventional technology using a plurality of cameras. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic three-dimensional configuration of an ultra-wide viewing angle imaging device (an example in which the imaging device is a regular icosahedron) according to an embodiment of the present invention. [Figure 2] 2 is a conceptual diagram showing the layered relationship of a substrate, a pixel, a photoelectric conversion film, a counter electrode, and element lenses in a part of one pixel area of ​​the ultra-wide viewing angle imaging device shown in FIG. 1. FIG. [Figure 3] 2 is a schematic diagram showing an example of a pixel arrangement on one surface of the ultra-wide viewing angle imaging device shown in FIG. 1. [Figure 4] 2A is a schematic diagram showing the unfolded state of the polyhedral ultra-wide viewing angle imaging device shown in FIG. 1, and FIG. 2B is a schematic diagram showing the assembled state formed by folding and assembling the unfolded substrates. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific configurations of an ultra-wide viewing angle imaging device and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings. The ultra-wide viewing angle imaging device according to this embodiment is a device that can capture an image with a wider field of view (angle of view) than any other imaging method used in television cameras.

[0016] <Ultra-wide viewing angle imaging device> FIG. 1 shows a perspective view of an ultra-wide viewing angle imaging device 100 according to an embodiment of the present invention, and FIG. 2 is a schematic diagram for facilitating understanding of the arrangement of each component on one imaging surface of this ultra-wide viewing angle imaging device 100 (in practice, it is also possible to have a structure in which each component (member) is stacked without any gaps).

[0017] First, the concept of the ultra-wide viewing angle imaging device according to this embodiment will be briefly explained with reference to FIG. The ultra-wide viewing angle imaging device of this embodiment is an imaging device consisting of a polyhedron, and as shown in Figure 4(a), it is formed by cutting a flat device based on plastic or the like to create an unfolded polyhedron, and then bending it along the solid line positions shown in Figure 4(a). That is, as mentioned above, in the prior art, a wide-angle imaging device equipped with a group of multiple cameras whose shooting directions are changed sequentially is known, but the ultra-wide viewing angle imaging device of this embodiment has a basic configuration of a polyhedron as shown in FIG. 1, with an image sensor and elemental lenses mounted on each surface. Each face of the above polyhedron is originally a divided part of a single device, as shown in the development diagram in Figure 4(a). Images captured on each face have overlapping parts between adjacent faces, and the pixel positions on each face can be easily identified because the device was originally continuous.

[0018] The number of faces and face shapes of the polyhedron can be selected from a variety of options. Not only regular polyhedrons such as a regular icosahedron (see Figure 1) or a regular dodecahedron, but also polyhedrons that combine different types of polygons, such as a soccer ball, can be selected. However, by using a regular polyhedron, the elemental images captured on each imaging plane can all be arranged symmetrically in the axial direction of each face with the same number of pixels, which makes it possible to efficiently assign each elemental image obtained from each imaging plane to be pasted onto the virtual sphere. The imaging angle of view of each imaging surface 3 is set to an angle equal to or larger than the angle (dihedral angle) between this imaging surface 3 and the adjacent imaging surface 3.

[0019] Next, a typical example of the arrangement of the components on one imaging surface 3 of the polyhedron will be described with reference to FIG. That is, each component provided on each imaging surface 3 is an imaging element, a portion of which is shown in FIG. 2, that receives light from above in the drawing and captures the subject image information carried by that light, and is configured so that a substrate 10, a plurality of pixels (TFT circuits (specifically including TFTs, pixel circuits, wiring, etc.)) 1, a photoelectric conversion film 12, a counter electrode 19, and element lenses 4 are stacked on top of each other and formed in this order on the substrate 10. 2, the pixel structure is such that the pixels 1 in the pixel area 5 (see FIG. 3; similarly in other drawings) are arranged in an array vertically and horizontally, but the arrangement of the pixels 1 is not limited to this, and for example, as shown in FIG. 3, the pixels 1 may be arranged in the shape of concentric equilateral triangles in accordance with the equilateral triangular imaging surface shape in the example of FIG. 1. In this way, by making the pixel area 5 in each imaging surface 3 the same shape as each imaging surface 3 of the polyhedron, the work of joining and synthesizing the elemental images is simplified, and the synthesis accuracy and work efficiency are improved.

[0020] 1, the element lens 4 is not limited to a single lens provided for one imaging surface 3, but a combination of multiple lenses can also be provided for one imaging surface 3. The configuration and shape of the element lens 4 can be appropriately selected from various types, including conventionally known types, depending on the situation.

[0021] Each wiring is arranged to pass through the boundary between pixels 1 and is electrically connected to each pixel 1, and is configured to read out pixel signals related to pixels 1 in a predetermined area (for example, one line) in parallel (with overlapping time). Also, as shown in Fig. 2, a TFT 17 is arranged adjacent to a corner of the pixel circuit of each pixel 1. It should be noted that the pixel structure described above can be of various types that are applied to a normal CMOS image sensor, regardless of the configuration described above.

[0022] Here, the arrangement of the pixels 1 in the pixel area 5 on each imaging surface 3 will be further explained. The pixels 1 can be arranged in an array other than a square pixel array in which pixels are arranged at equal intervals in an XY grid pattern, and for example, by making the pixel array rotationally symmetric (in the example shown in Figure 3, a rotationally symmetric shape every 120 degrees), symmetry can be further improved and degradation of resolution during image conversion can be prevented. When using a rotationally symmetric pixel array, for example, the pixels can be arranged so that a triangular shape is formed by line segments that are perpendicular to the wiring lead-out direction.

[0023] Furthermore, the wiring (such as wiring of a readout circuit not shown) may be electrically connected between adjacent imaging surfaces 3, but if there is a risk of disconnection at the boundary between adjacent imaging surfaces 3 when assembling them into a polyhedron, it is preferable to provide independent wiring for each imaging surface 3. Note that the boundary between adjacent imaging surfaces 3 can be formed into a slightly curved shape, and even when this boundary has a slightly curved shape, it will be referred to as a "polyhedron" in this specification.

[0024] For example, if the polyhedron is a regular icosahedron as shown in FIG. 1, the shape of each imaging surface 3 is an equilateral triangle, making it difficult to use the entire area of ​​the imaging surface 3 as an imaging area using the element lenses 4. Therefore, the peripheral areas near the vertices of the triangle on each surface become space that does not contribute to image synthesis. This space may be used to extend wiring to the back side. Alternatively, an imaging area consisting of a small lens and multiple pixels may be provided in that space to acquire information on the polarization state, acquire distance information in the imaging direction, or detect information related to the amount of light from the subject and the subject's movement, and automatically adjust the image quality of the captured image based on the detected information (e.g., a function to distinguish between bright and shaded areas and adjust the dynamic range for each imaging surface 3).

[0025] In this way, the ultra-wide viewing angle imaging device according to this embodiment is configured to be folded and assembled from the developed shape of a single device, which reduces variations in the characteristics of each image sensor on each imaging surface 3. This makes it possible to reduce the load on image processing such as color correction. Furthermore, because the device is constructed by folding a single sheet and assembling it three-dimensionally, alignment is easy and there is little possibility of misalignment when forming the device into a three-dimensional state. Furthermore, because the image sensors can be arranged efficiently, the overall system size can be made more compact than conventional systems that use an array of multiple cameras.

[0026] Furthermore, even in cases where a single device is cut into pieces for each imaging surface and attached to the corresponding surface of a base of the same shape as the polyhedron, it is possible to cut the device accurately along the boundaries between the surfaces of the unfolded figure, making it easier to accurately align adjacent surfaces without the need for complicated image correction processing, and reducing the possibility of misalignment, etc., compared to conventional technology.

[0027] Furthermore, when the polyhedron is formed as a regular polyhedron, it is desirable to draw the wiring from the back surface side as described above. In this case, by forming vias that lead from the position of each wiring on each imaging surface 3 to the back surface side, the wiring can be drawn to the back surface side. By using an area that is not the pixel area 5 as the area where the vias are formed, it is possible to achieve space efficiency as described above. It is also possible to attach an integrated circuit to the back side of each imaging surface 3, or to attach an integrated circuit to a space that does not contribute to the image synthesis described above. Furthermore, pixel signals may be extracted by directly drawing out wiring in a space that does not contribute to pixel synthesis to the outside, or by wirelessly transmitting the signals to the outside.

[0028] In the case of a 360-degree spherical camera, one method of compositing images is to map images taken from all directions onto a sphere, but this type of compositing method can also be selected from existing methods or methods to be developed in the future. In any case, when aligning images obtained from different planes, the relative positions can be easily determined by comparing the images from pixel 1 (for example, alignment pixel 1a shown in Figure 3) of adjacent images. The pixel arrangement can be determined arbitrarily, and is ultimately obtained by coordinate transformation to match the pixel positions of the display that displays the image mapped onto the sphere.

[0029] <Method of manufacturing an ultra-wide viewing angle imaging device> A method for manufacturing an ultra-wide viewing angle imaging device according to this embodiment will be described below with reference to FIGS. The manufacturing method of the ultra-wide viewing angle imaging device according to this embodiment is a method of manufacturing the ultra-wide viewing angle imaging device according to the above embodiment, and describes a method of sequentially stacking pixels (TFT circuits) 1, photoelectric conversion film 12, and counter electrodes 19 on a flexible and highly processable substrate 10 such as a plastic film.

[0030] First, a substrate 10 made of a flexible, cuttable, and bendable flat plastic film is processed into the shape shown in Fig. 4(a). That is, the substrate 1 is processed into the developed shape of a polyhedral ultra-wide viewing angle imaging device (first step). Next, in the developed figure of this polyhedron, pixels (TFT circuits) 1 each having a TFT, a pixel circuit, wiring, etc. are formed in each region corresponding to each imaging surface 3 using an existing semiconductor manufacturing process, and the pixels (TFT circuits) 1 are arranged to form a pixel area 5 of a predetermined shape (second step). As mentioned above, the shape of the pixel area 5 is preferably matched to the shape of the imaging surface 3. Furthermore, when wiring is provided on the back surface side, vias that electrically connect the front and back surfaces of the substrate 10 may be formed using a general processing technique such as plating.

[0031] As shown in FIG. 2, a photoelectric conversion film 12 using an organic photoelectric conversion material, selenium, or the like is laminated on top of the pixel (TFT circuit) 1. This photoelectric conversion film 12 can be made of various materials and device structures used in existing technologies. In addition, a counter electrode 19 is laminated on top of the photoelectric conversion film 12 as shown in Figure 2, but other structures required for photoelectric conversion processing, such as a hole blocking layer, an electron blocking layer, a barrier layer, etc., can also be appropriately adopted.

[0032] After carrying out the above-described manufacturing process, the substrate 10 is subjected to a predetermined bending process (including a process of cutting the substrate 10, if necessary) to assemble it into a three-dimensional shape, and is assembled into a polyhedron as shown in FIG. 4(b) (FIG. 4(b) shows only the faces around one vertex of the polyhedron) (third step). When assembling the polyhedron, the substrate 10 of each imaging surface 3 may be attached to a base having the same shape as the three-dimensional shape to be assembled.

[0033] Furthermore, the polyhedron is preferably formed by bending a single substrate 10 into a predetermined three-dimensional shape. However, if it is possible to attach it to a base as described above with high precision, it is also possible to cut off part or all of the substrate 10 for each imaging surface 3 and then attach it to the base. Unlike conventional techniques using multiple cameras, the captured images can be aligned with high precision, and in particular, if the substrate 10 is formed from a thin, flexible film, it can be easily attached to the base. Furthermore, if a plastic material is used for the substrate 10, it can be easily cut, so the processes of cutting and aligning the substrate 10 can be performed with high precision.

[0034] The above-mentioned wiring may be formed on the substrate 10 after the polyhedron is assembled into a three-dimensional shape. Various conventional techniques such as FPC and wire bonding can be applied to the wiring formation process. Furthermore, when forming wiring or an integrated circuit on the back surface, the wiring may be formed on the substrate 10 before assembling the polyhedron into a three-dimensional shape. Of course, wiring may be provided on both the front and back surfaces of the substrate 10, and the wiring on both surfaces may be electrically connected by the above-mentioned vias or the like.

[0035] After the polyhedron is assembled into a three-dimensional shape as described above, element lenses 4 are attached to each imaging surface 3 (fourth step). The element lenses 4 can be attached in various ways depending on the application. The element lenses 4 may be detachable by attaching a mount to each imaging surface 3, or may be fixedly attached via a jig or the like. The element lenses 4 may also be provided on the imaging surfaces 3 before the polyhedron is assembled.

[0036] Furthermore, the element lenses 4 may be configured by directly attaching a flat lens such as a metalens onto a laminate including the substrate 10, the pixel (TFT circuit) 1, the photoelectric conversion film 12, and the counter electrode 19, and the constituent materials, shape, etc. can be appropriately selected depending on the material and type of the laminate to be attached.

[0037] <Changes> The ultra-wide viewing angle imaging device and its manufacturing method of the present invention are not limited to those of the above-described embodiment, and various other modifications are possible. For example, although the imaging device in the above-described embodiment covers all directions, it is also possible to use a hemispherical imaging device that covers half of all directions, or a device that covers a predetermined part of all directions, depending on the application. That is, the ultra-wide viewing angle imaging device according to this embodiment is a multi-eye type, and various types that can combine images from different directions can be selected. The image to be acquired may be not only visible light but also infrared light, ultraviolet light, or other radiation, and can be selected depending on the use of the image to be acquired. Furthermore, it is possible to provide a member that functions as a light-shielding wall around the boundary between each imaging surface of the ultra-wide viewing angle imaging device of this embodiment, so that light that has passed through the lens of an adjacent imaging surface does not enter the imaging surface of the imaging surface.

[0038] In addition, in the manufacturing method of the ultra-wide viewing angle imaging device of the present invention, the order of the first step of cutting a shape corresponding to the unfolded diagram of multiple line-shaped flexible substrates that constitute a polyhedron or a predetermined area of ​​the outer surface of a portion of a polyhedron from a flexible plastic material, and the second step of forming multiple pixel areas, each consisting of an array of multiple imaging pixels including TFTs, pixel circuits, and wiring, along the longitudinal direction of each flexible substrate, at positions corresponding to the surface side of each flexible substrate in the unfolded diagram of the flexible substrate, can be selected depending on the situation. Furthermore, the order of the third step of bending a substrate having a shape corresponding to the unfolded figure at a predetermined position to form the polyhedron or a three-dimensional shape that will become part of the polyhedron, and the fourth step of arranging element lenses on each of these surfaces so that the subject image is formed in a pixel area consisting of multiple imaging pixels formed on the outer surface of each of these surfaces, can be selected depending on the situation. [Explanation of symbols]

[0039] 1 pixel (TFT circuit) 1a Alignment pixel 3 Imaging surface 4-element lens 5 pixel area 10 Substrate 12 Photoelectric conversion film 17 TFT 19 Counter electrode 100 Ultra-wide viewing angle imaging device

Claims

1. a substrate having an outer shape that is a polyhedron or a portion of a polyhedron; a pixel area in which a plurality of imaging pixels are arranged on each outer surface of the substrate; element lenses arranged on each of the surfaces so as to form an image of a subject on a pixel area formed on the outer surface of each of the surfaces; An ultra-wide viewing angle imaging device characterized in that the polyhedron, or a portion of the polyhedron, is shaped such that, when unfolded, the surfaces are arranged closely together on a single plane.

2. 2. The ultra-wide viewing angle imaging device according to claim 1, wherein each of said surfaces is formed from the same material.

3. 2. The ultra-wide viewing angle imaging device according to claim 1, wherein, when the polyhedron or a portion of the polyhedron is unfolded, each of the faces is a continuous body on a single plane.

4. 2. The ultra-wide viewing angle imaging device according to claim 1, wherein the substrate is made of a flexible plastic.

5. 5. The ultra-wide viewing angle imaging device according to claim 4, wherein the substrate is made of a film-like plastic.

6. 2. The ultra-wide viewing angle imaging device according to claim 1, wherein the pixel area is formed over the entire outer surface of each side of the substrate.

7. 7. The ultra-wide viewing angle imaging device according to claim 6, wherein the pixel area has a shape of a solid of revolution.

8. 2. The ultra-wide viewing angle imaging device according to claim 1, wherein the angle of view of each surface of the substrate is set to be equal to or larger than the angle between adjacent surfaces.

9. A first step of cutting a shape corresponding to a developed figure of a substrate having an outer shape of a polyhedron or a part of a polyhedron from a flexible plastic material; a second step of forming a pixel area in which a plurality of pixels, each including a TFT, a pixel circuit, and wiring, are arranged at a position corresponding to the front surface side of each surface of the developed figure, and disposing a photoelectric conversion film on the pixel area; a third step of bending the substrate having a shape corresponding to the developed figure at predetermined positions to form the polyhedron or a three-dimensional shape that will become a part of the polyhedron; a fourth step of arranging element lenses on each of the surfaces so that a subject image is formed on a pixel area consisting of a plurality of imaging pixels formed on the outer surface of each of the surfaces; A method for manufacturing an ultra-wide viewing angle imaging device, characterized in that, of these four steps, one step of a first step group consisting of two steps, the first step and the second step, is performed first and the other step is performed afterwards, and then one step of a second step group consisting of two steps, the third step and the fourth step, is performed first and the other step is performed afterwards.

10. The method for manufacturing an ultra-wide viewing angle imaging device described in claim 9, characterized in that when a substrate having a shape corresponding to the unfolded figure is bent or cut at a predetermined position to form a three-dimensional shape that will become the polyhedron or a part of the polyhedron, the substrate is attached to a base having the same shape as the polyhedron or a part of the polyhedron.

Images