A sub-screen device and a smart blackboard

Abstract

This application provides a secondary screen device and a smart blackboard; wherein, the secondary screen device includes a writing panel, a frame, and a baffle. The frame surrounds the writing panel and is fixedly connected to the writing panel; the baffle is detachably connected to the frame by a snap-fit ​​connection. This application solves the problems of time-consuming and laborious methods of fixing the baffle to the writing panel with screws, as well as the increased packaging and transportation costs of the secondary screen device.

Description

Technical Field

[0001] This application relates to the field of display screen technology, and in particular to a secondary screen device and a smart blackboard. Background Technology

[0002] A smart blackboard typically consists of a main screen and two secondary screens that can move relative to each other on either side of the main screen. Currently, in addition to the writing panel, the secondary screens also have a baffle and frame fixed to the side of the writing panel with screws. Once the writing panel, baffle, and frame of the secondary screens are assembled, they are ready for shipment.

[0003] However, fixing the baffle to the writing panel with screws is not only time-consuming and labor-intensive, but the baffle fixed to the writing panel also increases the thickness of the sub-screen device, increasing the packaging and transportation costs of the sub-screen device. Summary of the Invention

[0004] This application provides a secondary screen device and a smart blackboard, which can solve the problems of time-consuming and laborious methods of fixing the baffle to the writing panel with screws, as well as the increased packaging and transportation costs of the secondary screen device.

[0005] In a first aspect, this application provides a secondary screen device, comprising:

[0006] Writing panel;

[0007] A border, which surrounds the writing panel and is fixedly connected to the writing panel;

[0008] A baffle plate is detachably connected to the frame by a snap-fit ​​mechanism.

[0009] In conjunction with the first aspect, in some possible implementations, the frame includes a first surface and a second surface disposed opposite to each other, the writing panel is fixedly connected to the first surface, the second surface is provided with a snap-fit ​​groove, and the two opposite sidewalls of the snap-fit ​​groove are provided with opposing first stop portions, the first stop portions being adjacent to the second surface;

[0010] The baffle includes a connecting segment and an extension segment arranged sequentially in a direction away from the frame. The outer side of the connecting segment has a second stop portion formed therein. The connecting segment portion is inserted into the snap-fit ​​groove, and the second stop portion snaps into the first stop portion.

[0011] In combination with the first aspect and the above implementation, in some possible implementations, the two first stop portions facing each other have a first inclined surface that slopes from the first surface toward the bottom of the snap-fit ​​groove.

[0012] In combination with the first aspect and the above-described implementation, in some possible implementations, the second stop portion is formed with a second inclined surface that slides in cooperation with the first inclined surface.

[0013] In combination with the first aspect and the above implementation methods, in some possible implementation methods, a third stop portion is further provided on the outer periphery of the connecting segment;

[0014] The third stop and the second stop are spaced apart in the direction of insertion into the snap-fit ​​groove, so as to cooperate with the second stop to clamp the first stop.

[0015] In combination with the first aspect and the above implementation, in some possible implementations, the connecting segment further forms a clearance groove, which extends from the end of the connecting segment toward the first surface toward the extension segment.

[0016] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the bottom wall of the snap-fit ​​groove is provided with a protruding ridge, and the extending direction of the protruding ridge is consistent with the extending direction of the clearance groove.

[0017] When the connecting segment is inserted into the snap-fit ​​groove, the protruding ridge is adapted to be inserted into the clearance groove.

[0018] In combination with the first aspect and the above implementation, in some possible implementations, the clearance groove is stepped, including a large diameter portion and a small diameter portion that are connected to each other. The large diameter portion has an opening near the first surface, and the opening diameter of the large diameter portion is larger than the opening diameter of the small diameter portion.

[0019] The protruding ridge is located inside the large-diameter portion and has a gap between it and the wall surface of the large-diameter portion.

[0020] In combination with the first aspect and the above implementation, in some possible implementations, the two opposite sidewalls of the snap-fit ​​groove are provided with protrusions extending in opposite directions;

[0021] The distance between the two protrusions is equal to the distance between the two first stops.

[0022] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the thickness of the extension segment is less than the thickness of the connecting segment.

[0023] In combination with the first aspect and the above-described implementation, in some possible implementations, the extension section is provided with multiple reinforcing ribs at intervals on the side near the writing panel.

[0024] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the writing panel includes an outer panel, a honeycomb panel and an inner panel arranged sequentially;

[0025] The outer panel has an extension and a bend at its edge; the extension is fitted to the first surface of the frame.

[0026] The bent portion is located at the end of the extension away from the outer panel and bends away from the outer panel to clamp the frame.

[0027] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the frame is provided with a notch on the first surface;

[0028] The bent portion is inserted into the buckle groove.

[0029] In combination with the first aspect and the above-described implementation, in some possible implementations, the inner wall of the buckle groove is provided with a plurality of elastic protrusions that contact the bent portion.

[0030] In combination with the first aspect and the above implementation, in some possible implementations, the first surface is recessed to form a dispensing groove, which is used to fill the adhesive used to bond the writing panel.

[0031] Secondly, this application also provides a smart blackboard, including a main screen device and a secondary screen device as described in any of the first aspects above.

[0032] Compared to the current method of fixing the baffle to the writing panel with screws, the secondary screen device and smart blackboard of this application not only avoid failures such as stripping of screws when tightening them, but also directly eliminate the screw tightening process, improving production efficiency. Furthermore, the snap-fit ​​connection between the baffle and the frame is simple to operate. Therefore, when the smart blackboard is delivered from the factory, the baffle and the frame can be transported separately to the place of use, and assembled by the installers or users themselves. This does not increase the thickness of the secondary screen device, effectively reducing the packaging and transportation costs of the secondary screen device. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a secondary screen device provided in an embodiment of this application;

[0034] Figure 2 yes Figure 1 A cross-sectional view along line AA in the secondary screen device;

[0035] Figure 3 yes Figure 2 A magnified schematic diagram of a portion of the sub-screen device;

[0036] Figure 4 yes Figure 2 A schematic diagram of the frame structure in the secondary screen device;

[0037] Figure 5 yes Figure 2 A magnified view of a portion of the baffle in the secondary screen device.

[0038] The annotations in the attached figures are explained as follows:

[0039] 1—Writing panel; 11—Outer panel; 111—Extension; 112—Bending section; 12—Honeycomb panel; 13—Inner panel;

[0040] 2—Frame; 201—First surface; 202—Second surface; 21—Snap-fit ​​groove; 211—First stop; 2111—First bevel; 212—Protruding ridge; 213—Protrusion; 22—Snap-fit ​​groove; 221—Elastic protrusion; 23—Glue groove;

[0041] 3—baffle; 301—connecting section; 302—extension section; 31—second stop; 311—second inclined surface; 32—third stop; 33—recessed groove; 331—large diameter section; 332—small diameter section; 34—reinforcing rib. Detailed Implementation

[0042] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0043] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0044] In related technologies, the secondary screen device of a smart blackboard, in addition to the writing panel, also has a baffle and frame fixed to the side of the writing panel with screws. The frame seals the edges of the writing panel, and the baffle covers the sides of the writing panel, improving the product's visual appearance and preventing children from putting their hands behind the writing panel, making it safer for children to use the smart blackboard. The writing panel, baffle, and frame of the secondary screen device are assembled and then shipped. However, fixing the baffle to the writing panel with screws is not only time-consuming and labor-intensive, but the baffle also increases the thickness of the secondary screen device, raising packaging and transportation costs.

[0045] To address the aforementioned technical problems, embodiments of this application provide a secondary screen device and a smart blackboard. The secondary screen device provided in this application will now be described in detail with reference to the accompanying drawings.

[0046] Firstly, this application proposes a secondary screen device for use in a smart blackboard, which is used in combination with the main screen device of the smart blackboard to expand the display area or interactive area.

[0047] Specifically, please refer to Figure 1 and Figure 2 The secondary screen device includes a writing panel 1, a frame 2, and a baffle 3. The frame 2 surrounds the writing panel 1 and is fixedly connected to it; the baffle 3 is detachably connected to the frame 2 by a snap-fit ​​connection. Therefore, compared to the current method of fixing the baffle 3 to the writing panel 1 with screws, this solution not only avoids failures such as stripping when tightening screws, but also eliminates the screw-tightening process, improving production efficiency. Furthermore, the snap-fit ​​connection between the baffle 3 and the frame 2 is simple to operate. Therefore, when the smart blackboard is delivered, the baffle 3 and frame 2 can be transported separately to the user's location for self-assembly, thus not increasing the thickness of the secondary screen device and effectively reducing packaging and transportation costs.

[0048] Among them, the border 2 is set around the writing panel 1, which can be used as... Figure 1 The middle frame 2 is set around the three adjacent sides of the writing panel 1, or it can be set around the four sides of the writing panel 1. There are several ways to fix the frame 2 to the writing panel 1. In one possible implementation, the frame 2 can be fixedly connected to the writing panel 1 by adhesive. In another possible implementation, the frame 2 can also be fixedly connected to the writing panel 1 by clipping it with a buckle.

[0049] In summary, this solution can improve production efficiency, reduce material costs, increase container capacity, and reduce packaging and transportation costs, thereby solving the problems of time-consuming and labor-intensive methods of fixing the baffle 3 to the writing panel 1 with screws, as well as the increased packaging and transportation costs of the secondary screen device.

[0050] like Figure 3 , Figure 4 and Figure 5 As shown, in some embodiments of this application, the frame 2 includes a first surface 201 and a second surface 202 disposed opposite to each other. The writing panel 1 is fixedly connected to the first surface 201. The second surface 202 is provided with a snap-fit ​​groove 21. The two opposite sidewalls of the snap-fit ​​groove 21 are provided with first stop portions 211 extending towards each other. The first stop portions 211 are adjacent to the second surface 202.

[0051] The baffle 3 includes a connecting section 301 and an extension section 302 arranged sequentially in a direction away from the frame 2. A second stop portion 31 is formed on the outer side of the connecting section 301. The connecting section 301 is partially inserted into the snap-fit ​​groove 21, and the second stop portion 31 is snapped into the first stop portion 211.

[0052] Among them, the first surface 201 of the border 2 is Figure 3 The lower surface of the middle frame 2, the second surface 202 is Figure 3 The upper surface of the middle frame 2. The snap-fit ​​groove 21 on the second surface 202 provides space for accommodating the baffle 3. The direction away from the frame 2 is... Figure 3 The direction from bottom to top. The baffle 3 includes a connecting segment 301 and an extension segment 302 arranged sequentially in the direction away from the frame 2, that is, Figure 3 The baffle 3 includes a connecting section 301 and an extension section 302 from bottom to top. The connecting section 301 can extend into the snap-fit ​​groove 21. It can be understood that, in order to make the snap-fit ​​between the baffle 3 and the frame 2 more secure, the end face of the connecting section 301 contacts the bottom wall of the snap-fit ​​groove 21.

[0053] It should be noted that in this solution, two opposing first stop portions 211 are respectively provided on the two opposite sidewalls of the snap-fit ​​groove 21 to form a claw-like structure. At the same time, a second stop portion 31 is provided on the outer side of the connecting section 301 of the baffle 3 to form a hook-like structure. Through the snap-fit ​​of the first stop portion 211 and the second stop portion 31, that is, the combination of the claw and the hook, the baffle 3 and the frame 2 can be detachably connected by snap-fit.

[0054] In addition, the frame 2 and baffle 3 of this solution can be made by extruding plastic. The frame 2 and baffle 3 made of this material are lighter than the aluminum frame or sheet metal frame of the prior art. Moreover, the surface color is determined by the material itself, and there is no need to paint the surface, which is more economical and environmentally friendly.

[0055] like Figure 4 As shown, in some embodiments of this application, the two first stop portions 211 facing each other have a first inclined surface 2111 that is inclined from the first surface 201 toward the bottom of the slot 21.

[0056] As mentioned earlier, when the smart blackboard is delivered, the baffle 3 and the frame 2 can be transported separately to the user's location for self-assembly. Considering that users are not professional installers, it is necessary to improve the ease of assembly. Therefore, this solution provides a first inclined surface 2111 on the side facing the first stop 211. This serves two purposes: firstly, it guides and centers the components; secondly, it reduces the resistance when the first stop 211 and the second stop 31 engage, thus allowing the user to assemble the baffle 3 and the frame 2 more smoothly.

[0057] The inclination angle of the first inclined plane 2111 can be determined based on experience or through experimentation, and this application does not impose specific limitations on it.

[0058] like Figure 5 As shown, in some embodiments of this application, the second stop portion 31 is formed with a second inclined surface 311 that slides in cooperation with the first inclined surface 2111.

[0059] Understandably, similar to the function of the first inclined surface 2111 mentioned above, this solution forms a second inclined surface 311 in the second stop portion 31 that slides with the first inclined surface 2111, which can further improve the quick alignment when assembling the baffle 3 and the frame 2, and easily achieve the snap-fit ​​between the first stop portion 211 and the second stop portion 31.

[0060] The inclination angle of the second inclined surface 311 is adapted to the inclination angle of the first inclined surface 2111, and this application does not make any specific limitation on this.

[0061] like Figure 3 and Figure 5 As shown, in some embodiments of this application, a third stop 32 is also provided on the outer periphery of the connecting segment 301. The third stop 32 and the second stop 31 are spaced apart in the direction of insertion into the card slot 21, so as to cooperate with the second stop 31 to clamp the first stop 211.

[0062] Among them, see Figure 5 The structure of the third stop part 32 is similar to that of the second stop part 31, and they can be symmetrical about the horizontal direction.

[0063] It should be noted that the direction of inserting the card into slot 21 is... Figure 3 , Figure 5 The direction is from bottom to top. The third stop 32 and the second stop 31 are spaced apart, and the distance between them matches the thickness of the first stop 211. So that when the connecting section 301 is inserted into the snap-fit ​​groove 21, the second stop 31 snaps into the first stop 211, and at the same time, the third stop 32 clamps the first stop 211 to prevent the baffle 3 from tilting.

[0064] like Figure 3 and Figure 5 As shown, in some embodiments of this application, the connecting segment 301 is also formed with a clearance groove 33, which extends from the end of the connecting segment 301 toward the first surface 201 toward the extension segment 302.

[0065] Among them, the end face of the connecting segment 301 facing the first surface 201 is... Figure 5 The lower end face of the middle baffle 3 has a clearance groove 33 extending from the end face of the connecting section 301 toward the first surface 201 toward the extension section 302, that is, the clearance groove 33 extends from... Figure 5 The lower end face of the middle baffle 3 extends from bottom to top. Furthermore, the cross-section of the clearance groove 33 is... Figure 5The obstruction groove 33 extends along the length of the baffle 3 as shown.

[0066] It should be noted that the clearance groove 33 can divide the connecting section 301 of the baffle 3 into left and right parts, forming a tweezer-like structure. In this way, if the baffle 3 is damaged or needs to be disassembled, pressure can be applied inward from both sides of the baffle 3 to easily release the engagement between the second stop part 31 and the first stop part 211, thus separating the baffle 3 from the frame 2.

[0067] It is understood that the extension length of the clearance groove 33 needs to be determined based on factors such as the overall structural strength of the baffle 3 and the deformation of the connecting section 301 of the baffle 3 under pressure. This application embodiment does not make specific limitations.

[0068] like Figure 3 and Figure 4 As shown, in some embodiments of this application, the bottom wall of the snap-fit ​​groove 21 is provided with a protruding ridge 212, and the extending direction of the protruding ridge 212 is consistent with the extending direction of the clearance groove 33.

[0069] When the connecting section 301 is inserted into the card slot 21, the protrusion 212 is adapted to be inserted into the clearance slot 33.

[0070] It should be noted that the function of the protruding ridge 212 is to separate the two parts of the structure on the left and right sides of the clearance groove 33 at the connecting section 301 of the baffle 3, so as to prevent the forces acting on the two parts of the structure on the left and right sides of the connecting section 301 of the baffle 3 from being different when the baffle 3 is disassembled. This would cause one part of the structure (e.g., the right side part) to tilt excessively towards the other part of the structure (e.g., the left side part) beyond the middle of the bottom wall of the snap-fit ​​groove 21, thereby causing the part of the structure (e.g., the right side part) to suffer a cantilever-like fracture failure.

[0071] It is understood that, in one possible implementation, the protruding ridge 212 can be configured as a strip shape; specifically, the cross-section of the protruding ridge 212 can be as follows: Figure 3 As shown, it extends along the length of the border 2. In another possible implementation, there may be multiple protrusions 212 arranged in a row at intervals. The interval between adjacent protrusions 212 can be determined according to the actual situation and is not specifically limited here.

[0072] like Figure 5 As shown, in some embodiments of this application, the clearance groove 33 is stepped and includes a large diameter portion 331 and a small diameter portion 332 that are connected. The large diameter portion 331 has an opening near the first surface 201, and the opening diameter of the large diameter portion 331 is larger than the opening diameter of the small diameter portion 332.

[0073] The protruding ridge 212 is located inside the large diameter portion 331 and has a gap between it and the wall surface of the large diameter portion 331.

[0074] It should be noted that setting the clearance groove 33 as a stepped structure with a large-diameter portion 331 and a small-diameter portion 332 that are connected can ensure the rigidity of the baffle 3 and prevent bending instability. Furthermore, the opening diameter of the large-diameter portion 331 is larger than the opening diameter of the small-diameter portion 332, which allows sufficient distance to be reserved between the two parts of the structure at the connection section 301 of the baffle 3 and the protruding rib 212. As a result, when pressure is applied inward from both sides of the baffle 3, the deformation of the connection section 301 of the baffle 3 is large enough to smoothly release the engagement between the second stop portion 31 and the first stop portion 211, allowing the baffle 3 to separate from the frame 2.

[0075] like Figure 3 and Figure 4 As shown, considering that the end of the connecting section 301 of the baffle 3 facing the first surface 201 is located in the snap-fit ​​groove 21, forming a cantilever-like structure, if there is a gap between the end of the connecting section 301 facing the first surface 201 and the inner wall of the snap-fit ​​groove 21, the connection between the baffle 3 and the frame 2 will be unstable, and wobbling will occur. Therefore, in some embodiments of this application, the two opposite sidewalls of the snap-fit ​​groove 21 are provided with protrusions 213 extending towards each other. The distance between the two protrusions 213 is equal to the distance between the two first stop portions 211. In this way, the end of the connecting section 301 of the baffle 3 facing the first surface 201 can be clamped by the two protrusions 213, realizing a stable connection between the baffle 3 and the frame 2 and avoiding wobbling.

[0076] See Figure 2 In some embodiments of this application, the thickness of the extension section 302 is less than the thickness of the connecting section 301. This reduces the weight of the smart blackboard, saves materials, and lowers costs. The specific thickness of the extension section 302 can be determined based on the material and structural strength requirements of the baffle 3.

[0077] like Figure 2 As shown, in some embodiments of this application, the extension 302 is provided with a plurality of reinforcing ribs 34 at intervals on the side near the writing panel 1.

[0078] The number and spacing of the reinforcing ribs 34 can be determined according to actual needs.

[0079] It is understandable that by setting the reinforcing rib 34, the structural strength of the extension section 302 of the baffle 3 can be improved; thereby, the thickness of the extension section 302 can be further reduced, the weight of the smart blackboard can be further reduced, materials can be saved, and costs can be reduced.

[0080] like Figure 3As shown, in some embodiments of this application, the writing panel 1 includes an outer panel 11, a honeycomb panel 12, and an inner panel 13 arranged sequentially. The edge of the outer panel 11 has an extension 111 and a bent portion 112; the extension 111 is abutted against the first surface 201 of the frame 2. The bent portion 112 is located at the end of the extension 111 away from the outer panel 11 and bends away from the outer panel 11 to clamp the frame 2. Thus, the writing panel 1 and the frame 2 can be detachably and fixedly connected.

[0081] It should be noted that there are multiple ways to implement the clamping of the frame 2 by the bending part 112 in this application. In one possible implementation, such as Figure 3 and Figure 4 As shown, the frame 2 has a latching groove 22 on its first surface 201; the bent portion 112 is inserted into the latching groove 22, realizing the insertion of the bent portion 112 and the latching groove 22, thereby clamping the frame 2. Furthermore, it can also be done as follows... Figure 4 As shown, multiple elastic protrusions 221 are provided on the inner wall of the groove 22, which contact the bending portion 112. The friction between the elastic protrusions 221 and the bending portion 112 enhances the connection between the writing panel 1 and the frame 2. The number of elastic protrusions 221 can be two, three, etc., and the height of the protrusions can be adjusted according to the required tightness between the bending portion 112 and the groove 22. In another possible implementation, the extension 111 can be flush with the first surface 201 of the frame 2, allowing the bending portion 112 to fit against the side of the frame 2, directly clamping the frame 2.

[0082] like Figure 3 and Figure 4 As shown, in order to further improve the connection strength between the writing panel 1 and the frame 2, in some embodiments of this application, the first surface 201 is recessed to form an adhesive groove 23, which is used to fill the adhesive for bonding the writing panel 1.

[0083] It should be noted that the dispensing groove 23 can have various structural forms. In one possible implementation, the dispensing groove 23 can be set as a strip; specifically, the cross-section of the dispensing groove 23 can be as follows: Figure 4 As shown, it extends along the length of the border 2. In another possible implementation, there may be multiple dispensing grooves 23 arranged in a row at intervals. The spacing between adjacent dispensing grooves 23 can be determined according to the actual situation and is not specifically limited here.

[0084] Secondly, a second aspect of this application also proposes a smart blackboard, which includes a main screen device and a secondary screen device as described in any of the first aspects above.

[0085] The smart blackboard provided in this application, having the secondary screen device of the above embodiments, possesses all the beneficial effects of the aforementioned secondary screen device. The secondary screen device has been described in detail above and will not be repeated here.

[0086] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0087] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A secondary screen device, characterized in that, include: Writing panel; A frame, the frame surrounding the writing panel, the frame including a first surface and a second surface disposed opposite to each other, the writing panel being fixedly connected to the first surface, the second surface having a snap-fit ​​groove, the two opposite sidewalls of the snap-fit ​​groove having opposing extending first stop portions, the first stop portions being adjacent to the second surface, and the facing sides of the two first stop portions forming a first inclined surface that slopes from the second surface toward the bottom of the snap-fit ​​groove; and A baffle, comprising a connecting segment and an extension segment arranged sequentially in a direction away from the frame, wherein a second stop portion is formed on the outer side of the connecting segment; the connecting segment portion is inserted into the snap-fit ​​groove, and the second stop portion snaps into the first stop portion, wherein the second stop portion is formed with a second inclined surface that slides in cooperation with the first inclined surface; The connecting segment also forms a clearance groove, which extends from the end of the connecting segment toward the first surface toward the extension segment. The clearance groove is stepped and includes a large-diameter portion and a small-diameter portion that are connected. The large-diameter portion has an opening near the first surface, and the opening diameter of the large-diameter portion is larger than the opening diameter of the small-diameter portion. The bottom wall of the snap-fit ​​groove is provided with a protruding ridge in the middle, and the extension direction of the protruding ridge is consistent with the extension direction of the clearance groove. When the connecting segment is inserted into the snap-fit ​​groove, the protruding ridge is adapted to be inserted into the large-diameter portion, and there is a gap between it and the wall surface of the large-diameter portion.

2. The secondary screen device as described in claim 1, characterized in that, The outer periphery of the connecting section is also provided with a third stop; The third stop and the second stop are spaced apart in the direction of insertion into the snap-fit ​​groove, so as to cooperate with the second stop to clamp the first stop.

3. The secondary screen device as described in claim 1, characterized in that, The two opposite sidewalls of the snap-fit ​​groove are provided with protrusions extending towards each other; The distance between the two protrusions is equal to the distance between the two first stops.

4. The secondary screen device as described in claim 1, characterized in that, The thickness of the extension segment is less than the thickness of the connecting segment.

5. The secondary screen device as described in claim 4, characterized in that, The extension section is provided with multiple reinforcing ribs at intervals on the side closest to the writing panel.

6. The sub-screen device as described in any one of claims 1 to 5, characterized in that, The writing panel includes an outer panel, a honeycomb panel, and an inner panel arranged sequentially. The outer panel has an extension and a bend at its edge; the extension is fitted to the first surface of the frame. The bent portion is located at the end of the extension away from the outer panel and bends away from the outer panel to clamp the frame.

7. The secondary screen device as described in claim 6, characterized in that, The frame has a fastening groove on the first surface; The bent portion is inserted into the buckle groove.

8. The secondary screen device as described in claim 7, characterized in that, The inner wall of the buckle groove is provided with multiple elastic protrusions that contact the bending part.

9. The secondary screen device as described in claim 6, characterized in that, The first surface is recessed to form a dotted groove, which is used to fill the adhesive used to bond the writing panel.

10. A smart blackboard, characterized in that, It includes a main screen device and a secondary screen device as described in any one of claims 1 to 9.

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