Cleaning article

Abstract

A cleaning article comprising a first panel and a second panel, the first panel having: a first fibrous layer; and a first substrate attached to the first fibrous layer by a first connection type; the second panel has: a second fiber layer; and a second substrate attached to the second fibrous layer by a first connection type. The first connection type includes a first connection line parallel to a second connection line, the first connection line and the second connection line together straddling across a centerline of a respective panel, the centerline of the respective panel extending in an axial direction. The first panel is attached to the second panel by a plurality of point connections so as to form a pocket between the first panel and the second panel.

Description

Cross - Reference to Related Applications

[0001] The entire disclosure of U.S. Patent Application No. 17 / 478,700, filed on September 17, 2021, is incorporated herein by reference. Technical Field

[0002] The present disclosure generally relates to a cleaning article for attachment to a cleaning tool. The cleaning article can be used as a refill for the cleaning tool. Background Art

[0003] Generally, cleaning tools with cleaning articles (e.g., dust collectors) attachable thereto are known in the art. The cleaning article can be removed from the cleaning tool so that if the cleaning article becomes too dirty or over - used, the cleaning article can be removed and a new cleaning article can be attached in its place. Typically, the engaging portion of the cleaning tool is inserted into the cleaning article such that the cleaning article covers one end of the cleaning tool, such as the end opposite the handle of the cleaning tool. In this way, the user of the cleaning tool can grasp the handle and manipulate the cleaning article to clean properly. Such an arrangement is useful because it allows the user to more easily clean hard - to - reach places (e.g., by extending the user's reach).

[0004] Cleaning articles often have multiple fibers attached thereto to attract dust and other debris as the cleaning article passes over the surface to be cleaned. To obtain better cleaning and improved aesthetics, it is desirable to avoid portions of the cleaning article where there are no fibers. Summary of the Invention

[0005] In one embodiment, the present invention provides a cleaning article having a first panel and a second panel. The first panel has a first fiber layer and a first substrate attached to the first fiber layer by a first connection type; the second panel has a second fiber layer and a second substrate attached to the second fiber layer by the first connection type, wherein the first connection type includes a first connection line parallel to a second connection line, and the first connection line and the second connection line together straddle both sides of the center line of the corresponding panel, the center line of the corresponding panel extending in the axial direction, and wherein the first panel is attached to the second panel by a plurality of point connection portions so as to form a bag between the first panel and the second panel. Brief Description of the Drawings

[0006] Figure 1 A schematic diagram showing a panel of a cleaning article according to the present disclosure;

[0007] Figure 2 A schematic diagram showing a panel of a cleaning article according to the present disclosure;

[0008] Figure 3A perspective view of a panel of a cleaning article according to the present disclosure is shown;

[0009] Figure 4 A perspective view of a cleaning article according to the present disclosure attached to a cleaning tool is shown;

[0010] Figure 5 A perspective view of a cleaning article according to the present disclosure attached to a cleaning tool is shown;

[0011] Figure 6 A process of manufacturing a cleaning article according to the present disclosure is shown; and

[0012] Figure 7 A cleaning article according to the present disclosure at various stages during the Figure 6 process is shown. DETAILED DESCRIPTION

[0013] To improve the prior art, the present application describes a cleaning article whose connecting wires are not easily visible. The cleaning article also has a 360° appearance, which not only improves the aesthetics but also increases the functionality of the cleaning article, since all sides of the cleaning article can be used for cleaning. The cleaning article can be attached to a cleaning tool, such as the cleaning tool described in U.S. Patent Application No. 17 / 478,700, and used as a refill once the existing cleaning article is no longer suitable for cleaning.

[0014] Figure 1 A schematic view of an exemplary panel 2 according to the present application is shown. Two such panels 2 are connected to each other to form a cleaning article. However, for simplicity, the discussion will initially focus on a single discrete panel 2.

[0015] The panel 2 is prepared by obtaining a fiber layer 4 and attaching it to a substrate 6. The fiber layer 4 includes a plurality of cleaning fibers for collecting dust and debris during cleaning with the cleaning article. The cleaning fibers generally extend in a radial direction R. The cleaning ability of the cleaning fibers can be increased by spraying oil on the cleaning fibers. The cleaning fibers can be made of polyester, can be virgin material, recycled material, or a mixture thereof, and have a gram mass of about 2.5 to 3.5 decitex per 10,000 meters of fiber. Adding virgin material to the cleaning fibers helps facilitate the attachment of the fiber layer 4 to the substrate 6.

[0016] The substrate 6 can be, for example, a nonwoven sheet. The nonwoven sheet can be made of spunbond nonwoven materials such as polyester and / or polypropylene, and the material can be virgin, recycled, or a mixture thereof. The nonwoven sheet can have a weight of about 35 g / m 2 ². The substrate 6 has a substrate edge 7. The substrate edge 7 in turn has various components, which will be further explained in detail below.

[0017] Attach the fibrous layer 4 to the substrate 6 using a first type of connection 8. The first type of connection 8 can be a type of connection known in the art. In one embodiment, the first type of connection 8 includes two separate connection lines 10 extending in the axial direction A along the length L of the panel 2. Each connection line 10 can be, for example, an ultrasonic weld having a specific shape, which is formed by ultrasonic welding techniques. The width of the connection line 10 can be approximately 1.29 mm or 1.5 mm. Each connection line 10 is located on one side of the centerline 12 of the panel 2 such that the connection lines 10 straddle the centerline 12 together. The distance from the first connection line 10 on one side of the centerline 12 to the second connection line 10 on the other side of the centerline 12 can be approximately 5 mm. After the cleaning article is assembled, the cleaning fibers of the fibrous layer 4 cover the centerline 12, which makes the centerline 12 not easily visible and helps to create a 360° appearance of the cleaning article.

[0018] The connection lines 10 can have a specific shape. For example, each connection line 10 can have a zigzag shape (as shown in Figure 1 ), or a wavy shape (as shown in Figure 2 ). The two connection lines 10 can be parallel to each other. Figures 1 to 2 Various exemplary dimensions of the connection lines 10 and the panel 2 as a whole are shown in

[0019] Once the panel 2 is prepared, attach the panel 2 to another identical panel 2 to manufacture the cleaning article. Specifically, the two panels 2 are arranged one on top of the other, and then connected to each other using a second type of connection 14. The second type of connection 14 can be a type of connection known in the art. The second type of connection 14 can include a plurality of point connection portions 16. In one embodiment, each point connection portion 16 can be an ultrasonic weld having a specific shape, which is formed by ultrasonic welding techniques. For example, the point connection portion 16 can have a generally oval or circular shape, with a major axis length of approximately 5 mm and a minor axis length of approximately 3 mm. The plurality of point connection portions 16 are applied along the length L and are generally symmetric and radially offset with respect to the centerline 12. Connecting the two panels 2 together in this way creates a pocket 18 between the two panels 2. Thus, a cleaning tool can be inserted into the pocket 18 of the cleaning article such that the cleaning article can be attached to the cleaning tool, for example, by hooking at least a portion of the cleaning tool into a hole 19 in the substrate 6.

[0020] As shown in Figures 1 to 2As shown, a plurality of point connections 16 can be divided into at least two different groups. In a first group 20, on one side of the centerline 12, a given point connection 16 is spaced from an adjacent point connection 16 by a first distance D1. In a second group 22, on one side of the centerline 12, a given point connection 16 is spaced from an adjacent point connection 16 by a second distance D2. The second distance D2 is greater than the first distance D1. The first group 20 of point connections 16 is arranged toward the end end 24 of the panel 2, while the second group 22 of point connections 16 is arranged toward the handle end 26 of the panel 2, closer to the location where the cleaning tool will be inserted into the bag 18. In this way, the first group 20 of point connections 16 is closer together at the end end 24 to ensure a good fit of the cleaning tool and that the cleaning tool does not puncture the bag 18 of the cleaning article during insertion and cleaning. However, the second group 22 of point connections 16 is spaced farther apart to create a wider insertion area for the bag 18 and contribute to a 360° appearance of the cleaning article.

[0021] The arrangement of the point connections 16 described herein also contributes to the loose ends of the cleaning fibers of the fiber layer 4 having different lengths. For example, some cleaning fibers are connected to each other only by the connecting lines 10 of the first connection type 8, while other cleaning fibers are connected to each other by both the connecting lines 10 of the first connection type 8 and the point connections 16 of the second connection type 14. The loose ends of the cleaning fibers having various different lengths contribute to improving the cleaning ability of the cleaning article.

[0022] The first group 20 of point connections 16 and the second group 22 of point connections 16 also generally correspond to different parts of the substrate edge 7. In particular, the front edge 7A of the substrate edge 7 is located at the end end 24 of the panel 2, adjacent to one end of the first group 20 of point connections 16. The front edge 7A generally extends in the radial direction R.

[0023] The first longitudinal edge 7B extends from the front edge 7A on both sides of the centerline 12. The first longitudinal edge 7B generally extends in the axial direction A, approximately as far as the first group 20 of point connections 16 extends along the length L of the panel 2. The angle between the front edge 7A and the first longitudinal edge 7B is a first angle α1. The first angle α1 is greater than 90°. For example, the first angle α1 can be 102°, as Figures 1 to 2 shown.

[0024] When continuing along the length L of the panel 2, the first longitudinal edge 7B abuts the second longitudinal edge 7C. The second longitudinal edge 7C generally extends in the axial direction A approximately as far as the second group 22 of point connections 16 extends along the length L of the panel 2. The angle between the front edge 7A and the second longitudinal edge 7C is a second angle α2. The second angle α2 is also greater than 90°. For example, the second angle α2 can be 95°, as Figures 1 to 2 shown.

[0025] The first angle α1 is greater than the second angle α2. In this way, for a given substrate 6, the first longitudinal edge 7B and the second longitudinal edge 7C on one side of the center line 12 are not parallel to the first longitudinal edge 7B and the second longitudinal edge 7C on the other side of the center line 12, respectively. Thus, each substrate 6 (i.e., when each substrate 6 is presented in the assembled cleaning article) can generally have the shape of a triangle, a cone, or an arrow, with non-parallel longitudinal edges.

[0026] Figure 3 A perspective view of a panel 2 after its assembly is shown. The panel 2 includes a zigzag connecting line 10, as Figure 1 shown. The cleaning fibers of the fiber layer 4 extend from the connecting line 10 in the radial direction R and the axial direction A. The substrate 6 is visible and accessible near the handle end 26 of the panel 2. The substrate 6 includes holes 19 for attaching at least a part of a cleaning tool so as to hold the panel 2 (and another panel 2 attached thereto) on the cleaning tool.

[0027] Figure 4 A perspective view of two panels 2 after they have been assembled, for example, by being connected with a second connection type 14 (e.g., a plurality of point connections 16), is shown. The two connected panels 2 together form a cleaning article 28. When the two panels 2 are connected to each other, generally, upon a cursory inspection of the cleaning article 28, neither the connecting line 10 of the first connection type 8 nor the point connections 16 of the second connection type 14 are visible. As shown, the cleaning article 28 also does not include any area in its cross-section that is free of cleaning fibers (i.e., the fiber layer 4), which helps contribute to the overall 360° appearance of the cleaning article 28.

[0028] As Figure 4 shown, a cleaning tool 30 has been inserted into a pocket 18 of the cleaning article 28, which is formed after the two panels 2 are connected to each other. To fix the cleaning tool 30 to the cleaning article 28, at least one protrusion 32 of the cleaning tool 30 has been hooked into a hole 19 on the substrate 6 of one of the panels 2. In this way, when a user uses the resulting cleaning device 34 for cleaning or dusting, the cleaning article 28 is fixed to the cleaning tool 30 and held in place by the protrusion 32.

[0029] Figure 5 A Figure 4 wider-angle view of the cleaning device 34 is shown. It can be seen that the cleaning tool 30 includes a handle 36, which a user of the cleaning device 34 can grasp to manipulate the cleaning article 28 when the cleaning article 28 is attached to the cleaning tool 30. The cleaning tool can be substantially as described in the parent case of the present application, U.S. Patent Application No. 17 / 478,700, filed on September 17, 2021.

[0030] Figure 6 A simplified method for manufacturing a cleaning article 28 is shown. It can be seen that the method includes four process lines. The first process line 38 and the second process line 40 are combined to manufacture the first panel 2. In particular, the first process line 38 includes a continuous roll of the fibrous layer 4, and the second process line 40 is arranged adjacent thereto and includes a continuous roll of the substrate 6. At the same time, the third process line 42 and the fourth process line 44 are combined to manufacture the second panel 2. In particular, the third process line 42 includes a continuous roll of the fibrous layer 4, and the fourth process line 44 is arranged adjacent thereto and includes a continuous roll of the substrate 6. The first process line 38 and the second process line 40 are arranged generally adjacent to (e.g., above) the third process line 42 and the fourth process line 44.

[0031] In the first step of the method, the substrate 6 from the second process line 40 and the substrate 6 from the third process line 42 each pass through a pair of rollers 46, 48 respectively. When passing through the pair of rollers 46, 48, each substrate 6 is folded at one of its ends. These ends will ultimately become the parts of each substrate 6 that form the bag 18. Folding the ends of each substrate 6 helps to structurally strengthen those areas and ultimately the part of the bag 18 near the handle end 26 of the cleaning article 28. For example, due to the folding, the substrate 6 of each panel 2 becomes twice as thick, facilitating the secure attachment of the cleaning article 28 to the protrusion 32 when the finished cleaning article 28 is attached to the cleaning tool 30. Folding each substrate 6 also helps to facilitate the connection of the substrate 6 of the first panel 2 to the substrate 6 of the second panel 2, thereby extending the bag 18 to include the folded portions of each substrate 6.

[0032] In the next step, still in the second process line 40 and the third process line 42, the folded substrates 6 each pass through another pair of rollers 50, 52 respectively. In this step, the rollers 50, 52 perforate the substrates 6. Perforating the substrates 6 forms the substrate edges 7 and facilitates the separation of each discrete substrate 6 from its continuous roll in later production. At the same time or approximately at the same time, in the first process line 38 and the fourth process line 44, the first fibrous layer 4 and the second fibrous layer 4 each pass adjacent to oil sprayers 54, 56 respectively. The oil sprayers 54, 56 apply a light oil coating to the first and second fibrous layers 4. For example, each oil sprayer 54, 56 can apply approximately 0.5 g of oil to its corresponding fibrous layer 4.

[0033] In a next step, the fiber layer 4 from the first process line 38 and the substrate 6 from the second process line 40 are brought close to each other so as to attach the fiber layer 4 and the substrate 6 using the first connection type 8. Similarly, the fiber layer 4 from the third process line 42 and the substrate 6 from the fourth process line 44 are brought close to each other so as to also attach the fiber layer 4 and the substrate 6 using the first connection type 8. In particular, the connecting device 58 can be used to apply the first connection type 8 to connect the fiber layer 4 of the first process line 38 to the substrate 6 of the second process line 40 to produce the first panel 2. In addition, the connecting device 60 can be used to apply the first connection type 8 to connect the fiber layer 4 of the third process line 42 to the substrate 6 of the fourth process line 44 to produce the second panel 2. The connecting devices 58, 60 can be, for example, ultrasonic welding machines.

[0034] Then, the first panel 2 of the first process line 38 and the second process line 40 is brought closer to the second panel 2 of the third process line 42 and the fourth process line 44 so as to attach the first panel 2 and the second panel 2 using the second connection type 14. In particular, the connecting device 62 can be used to apply the second connection type 14 (e.g., a plurality of dot connections 16) to connect the first panel 2 of the first process line 38 and the second process line 40 to the second panel 2 of the third process line 42 and the fourth process line 44. The connecting device 62 can be, for example, an ultrasonic welding machine.

[0035] Finally, the combined first panel 2 and second panel 2 are passed through a cutting device 64 to produce the cleaning article 28, and each successive cut of the cutting device 64 separates an additional cleaning article 28 from the combined continuous material roll.

[0036] Figure 7 The cleaning article 28 is shown at various stages during the Figure 6 method. Figure 7 The fiber layer 4 of the first process line 38 and the substrate 6 of the second process line 40 are shown at the top left, at which time they are being combined. First, the substrate 6 is folded. Next, the substrate 6 is perforated 66 so as to facilitate the formation of a substrate edge 7 for the substrate 6. Thereafter, the fiber layer 4 is attached to the substrate 6 using the first connection type 8 (i.e., by forming a connecting line 10) to produce a roll of the first panel 2. As Figure 7 shown at the bottom left of

[0037] As Figure 7As shown in the intermediate image, the first panel 2 (i.e., the panel 2 produced by the first process line 38 and the second process line 40) and the second panel 2 (i.e., the panel 2 produced by the third process line 42 and the fourth process line 44) are connected using the second connection type 14 (e.g., a plurality of point connections 16), thereby creating a pocket 18 between the first panel 2 and the second panel 2. Additional connection lines 68 can be used to connect portions of the substrates 6 of the first and second panels 2 that do not have the fibrous layer 4, to further define and structurally strengthen the pocket 18, and specifically the portion of the pocket 18 into which the cleaning tool 30 is initially inserted.

[0038] Thereafter, as Figure 7 shown on the right side of, the excess portions of each substrate 6 are removed along the perforations 66 to form the substrate edges 7. Additionally, the cleaning fibers of the fibrous layer 4 of each panel 2 are then cut in order to provide a resulting cleaning article 28 having a desired shape.

[0039] Although the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It is to be understood that changes and modifications can be made by those of ordinary skill in the art within the scope of the following claims. In particular, the invention covers additional embodiments having any combination of the features of the different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to one embodiment of the invention and not necessarily all embodiments.

[0040] The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the articles "a" or "the" when introducing an element should not be construed as excluding a plurality of elements. Similarly, the recitation of "or" should be construed as inclusive, such that the recitation of "A or B" does not exclude "A and B", unless it is clearly indicated from the context or the foregoing description that only one of A and B is intended. Additionally, the expression "at least one of A, B, and C" should be construed as one or more of the group of elements consisting of A, B, and C, and should not be construed as requiring at least one of each of the listed elements A, B, and C, whether A, B, and C are related as a category or otherwise. Further, the recitation of "A, B, and / or C" or "at least one of A, B, or C" should be construed as including any singular entity from the listed elements, such as A, any subset from the listed elements, such as A and B, or the entire list of elements A, B, and C.

[0041] List of Reference Numerals 2 Panel 4 Cleaning article 6 Substrate 7 Substrate edge 7A Front edge 7B First longitudinal edge 7C Second longitudinal edge 8 First connection type 10 Connecting line 12 Center line 14 Second connection type 16 Point connection part 18 Bag 19 Hole 20 First group 22 Second group 24 End end 26 Handle end 28 Cleaning product 30 Cleaning tool 32 Protrusion 34 Cleaning device 36 Handle 38 First process line 40 Second process line 42 Third process line 44 Fourth process line 46 Roller 48 Roller 50 Roller 52 Roller 54 Oil sprayer 56 Oil sprayer 58 Connecting device 60 Connecting device 62 Connecting device 64 Cutting device 66 Perforation 68 Additional connecting line α1 First angle α2 Second angle A Axial direction D1 First distance D2 Second distance L Length of panel 2 R Radial direction

Claims

1. A cleaning article, the cleaning article comprising: A first panel, the first panel comprising: A first fiber layer; and A first substrate, the first substrate being attached to the first fiber layer by a first type of connection; and A second panel, the second panel comprising: A second fiber layer; and A second substrate, the second substrate being attached to the second fiber layer by the first type of connection, wherein the first type of connection includes a first connection line parallel to a second connection line, the first connection line and the second connection line together straddle both sides of the center line of the corresponding panel, the center line of the corresponding panel extending in the axial direction, and wherein the first panel is attached to the second panel by a plurality of point connection portions so as to form a bag between the first panel and the second panel.

2. The cleaning product according to claim 1, wherein The first substrate and the second substrate each have: a front edge extending in the radial direction; a first longitudinal edge extending in the axial direction, the first longitudinal edge adjoining the front edge; and a second longitudinal edge extending in the axial direction, the second longitudinal edge adjoining the first longitudinal edge.

3. The cleaning product according to claim 2, wherein For the corresponding panel, the first longitudinal edge forms a first angle with respect to the front edge, and the second longitudinal edge forms a second angle with respect to the front edge.

4. The cleaning article according to claim 3, wherein, The first angle is greater than the second angle.

5. The cleaning product according to claim 2, wherein, The plurality of point connection portions includes a first group of point connection portions and a second group of point connection portions, wherein the first group of point connection portions extends along the length of the corresponding panel, extending approximately as far as the first longitudinal edge in the axial direction, and wherein the second group of point connection portions extends along the length of the corresponding panel, extending approximately as far as the second longitudinal edge in the axial direction.

6. The cleaning article according to claim 1, wherein the first substrate and the second substrate each have: two first longitudinal edges, one first longitudinal edge on each side of the center line of the corresponding panel; and two second longitudinal edges, one second longitudinal edge on each side of the center line of the corresponding panel, all longitudinal edges extending generally in the axial direction, Among them, for the corresponding panel, the two first longitudinal edges are not parallel to each other, and wherein, for the corresponding panel, the two second longitudinal edges are not parallel to each other.

7. The cleaning product according to claim 6, wherein, On both sides of the center line of the corresponding panel, one first longitudinal edge adjoins one second longitudinal edge.

8. The cleaning product according to claim 7, wherein, The first substrate and the second substrate each have a front edge extending in the radial direction, and wherein, for the corresponding panel, the front edge adjoins each of the two first longitudinal edges.

9. The cleaning article according to claim 1, wherein, The plurality of point connection portions includes a first group of point connection portions and a second group of point connection portions, wherein the point connection portions in the first group of point connection portions are separated from each other by a first distance, and wherein the point connection portions in the second group of point connection portions are separated from each other by a second distance.

10. The cleaning article according to claim 9, wherein, The second distance is greater than the first distance.

11. The cleaning product according to claim 10, wherein, The cleaning article has a distal end portion and a handle end portion opposite the distal end portion, and wherein the first group of point connection portions is closer to the distal end portion, and the second group of point connection portions is closer to the handle end portion.

12. The cleaning product according to claim 1, wherein The first connecting line and the second connecting line each have a zigzag shape.

13. The cleaning product according to claim 1, wherein, The first connecting line and the second connecting line each have a wavy shape.

14. A cleaning tool, comprising: The cleaning article according to claim 1; and A flexible frame element configured to be coupled to a handle assembly, the flexible frame element comprising: A base; At least three elongate arms, each of the at least three elongate arms having a base end and a distal end, the base ends extending from the base and being spaced apart from each other at the base, the elongate arms being flexible and resilient; A plurality of transverse members extending between the elongate arms; and A plurality of movable hinges disposed between the plurality of transverse members and the elongate arms, wherein a force applied to at least one of the elongate arms is transmitted to at least one of the other elongate arms through the plurality of transverse members and the plurality of movable hinges, and wherein the cleaning article is disposed on the flexible frame element.

15. The cleaning tool according to claim 14, wherein, The first substrate and the second substrate each have: a front edge extending in a radial direction; a first longitudinal edge extending in the axial direction, the first longitudinal edge adjoining the front edge; and a second longitudinal edge extending in the axial direction, the second longitudinal edge adjoining the first longitudinal edge.

16. The cleaning tool according to claim 15, wherein, For a corresponding panel, the first longitudinal edge forms a first angle relative to the front edge, and the second longitudinal edge forms a second angle relative to the front edge.

17. The cleaning tool according to claim 16, wherein, The first angle is greater than the second angle.

18. A method of manufacturing a cleaning article, the method comprising: Forming a first panel by attaching a first fiber layer to a first substrate using a first connecting line parallel to a second connecting line, the first connecting line and the second connecting line together straddling both sides of a center line of the first panel, the center line of the first panel extending in an axial direction; Forming a second panel by attaching a second fiber layer to a second substrate using a third connecting line parallel to a fourth connecting line, the third connecting line and the fourth connecting line together straddling both sides of a center line of the second panel, the center line of the second panel extending in the axial direction; and Attaching the first panel to the second panel using a plurality of point connections to form a bag between the first panel and the second panel.

19. The method according to claim 18, wherein, The first substrate and the second substrate each have: two first longitudinal edges, one first longitudinal edge on each side of the center line of the corresponding panel; and two second longitudinal edges, one second longitudinal edge on each side of the center line of the corresponding panel, all longitudinal edges extending generally in the axial direction, wherein, for a corresponding panel, the two first longitudinal edges are not parallel to each other, and wherein, for a corresponding panel, the two second longitudinal edges are not parallel to each other.

20. The method according to claim 19, wherein, On both sides of the center line of the corresponding panel, one first longitudinal edge adjoins one second longitudinal edge, wherein the first substrate and the second substrate each have a front edge extending in a radial direction, and Wherein, in the corresponding panel, the front edge is adjacent to each of the two first longitudinal edges.

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