An electromagnetic digital screen

Abstract

The present invention discloses an electromagnetic digital screen, including a bottom shell and a top cover, wherein a receiving cavity is formed between the bottom shell and the top cover, and a circuit board layer, a light source layer, a light guide layer and a display layer are stacked in sequence from bottom to top in the receiving cavity, and further including: a luminous body, wherein a plurality of luminous bodies are arranged in an array on the upper surface of the light source layer, and the upper end of the luminous body abuts against the light guide layer; the light source layer can be movably arranged, and a movable interval is reserved between the lower end and the circuit board layer; an inertia component, which is fixedly arranged in the receiving cavity and has a movable counterweight. The present invention arranges the inertia component, and when the bottom shell and the top cover are impacted, the counterweight moves under inertia, and since a movable interval is reserved between the light source layer and the circuit board layer, the moving counterweight is linked to the light source layer through the linkage component to move away from the light guide layer, thereby achieving that at the moment of impact, the light source layer is away from the light guide layer to avoid the luminous body from being subjected to rigid impact, and the luminous body is protected from damage.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic screens, and in particular to an electromagnetic digital screen. Background Art

[0002] Electromagnetic digital screen, referred to as electromagnetic screen, refers to an electromagnetic touch screen that uses electromagnetic induction technology to achieve precise touch and original handwriting. It needs to be used with an electromagnetic pen to achieve touch. The existing electromagnetic screen can basically meet the daily use needs, but there are still some shortcomings that need to be improved.

[0003] Patent document CN212647450U disclosed an electromagnetic digital screen on the announcement date of March 2, 2021, and its technical solution includes: an electromagnetic input module and a light-emitting module, the electromagnetic input module includes a base layer, a magnetic isolation plate and a touch layer, and the touch layer and the magnetic isolation plate are respectively arranged on two opposite side surfaces of the base layer. The light-emitting module includes a plurality of light sources, and the plurality of light source arrays are arranged on one side surface of the base layer and on the same side as the touch layer. Its beneficial effect is: on the premise that the electromagnetic input module is not interfered with, the point light source and the touch layer are arranged on the same side surface of the base layer, and the backlight module and the electromagnetic input module are integrated into an integrated structure, which reduces components and facilitates assembly, making the overall structure more compact, further reducing the overall thickness of the electromagnetic handwriting screen, and making it thinner and lighter.

[0004] As in the prior art of the above-mentioned patent, a plurality of functional layers are stacked inside an electromagnetic screen of thin thickness. When the screen is subjected to external impact such as falling, each layer of the structure is in direct rigid contact. In particular, when external pressure acts on the light source module, the light-emitting bodies integrated on the light source module, such as lamp beads, are easily directly damaged by the above rigid impact and pressure. Therefore, an electromagnetic digital screen is urgently needed to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide an electromagnetic digital display to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An electromagnetic digital screen comprises a bottom shell and a top cover, wherein a receiving cavity is formed between the bottom shell and the top cover, wherein a circuit board layer, a light source layer, a light guide layer and a display layer are stacked in sequence from bottom to top in the receiving cavity, and further comprises: a plurality of illuminants are arranged in an array on the upper surface of the light source layer, wherein the upper end of the illuminants abuts against the light guide layer; the light source layer can be movably arranged, and a movable interval is reserved between the lower end and the circuit board layer; an inertia component, which is fixedly arranged in the receiving cavity and has a movable counterweight; and a linkage component, which is used to link the counterweight and the light source layer, wherein when the bottom shell and the top cover are impacted, the counterweight moves under inertia and links the light source layer through the linkage component to move away from the light guide layer.

[0008] Preferably, a limiting hook is fixedly provided on the inner side of the top cover, and the limiting hook limits the light guide layer and the display layer to be disposed close to the inner wall of the top cover.

[0009] Preferably, a plurality of first elastic members are evenly arranged between the inner bottom surface of the bottom shell and the light source layer, and the first elastic members maintain elasticity to push the light source layer upward.

[0010] Preferably, the inertia assembly includes a movable bin fixedly connected to the inner bottom surface of the bottom shell, the counterweight is slidably arranged in the movable bin and second elastic members are arranged at both upper and lower ends to resist the inner top surface and inner bottom surface of the movable bin.

[0011] Preferably, the linkage assembly includes a lever rotatably arranged on the inner bottom surface of the bottom shell and a slide plate movably arranged on the outer wall of the movable warehouse, the counterweight is provided with a first sliding pin that movably passes through the movable warehouse, one end of the lever is provided with a first sliding ring that is slidably connected to the first sliding pin, a linkage part is slidably arranged on the slide plate, the side wall of the linkage part is hinged to the other end of the lever, a second sliding pin is fixedly arranged on the side wall of the slide plate, and a second sliding ring that is slidably connected to the second sliding pin is provided on the side of the light source layer.

[0012] Preferably, a guide post is fixedly provided on the outer side wall of the movable chamber close to the light source layer, and a guide hole matching the guide post is provided on the slide plate.

[0013] Preferably, a support is fixedly provided on the inner bottom surface of the bottom shell, and the middle position of the lever is hinged to the upper end of the support.

[0014] Preferably, the second sliding ring is arranged to be inclined upward at one end close to the movable bin.

[0015] Preferably, the part where the bottom shell and the top cover are connected is wedge-shaped, and the side wall of the bottom shell is provided with a locking component for fixing the top cover.

[0016] Preferably, the locking assembly comprises a screw movably penetrating the side wall of the bottom shell, and the inner side wall of the top cover is provided with a connecting piece extending downward, and the connecting piece is provided with a screw hole matching the screw.

[0017] In the above technical solution, the beneficial effects of the present invention are:

[0018] The electromagnetic digital screen is provided with an inertial component. When the bottom shell and the top cover are impacted, the counterweight moves under inertia. Since a movable gap is reserved between the light source layer and the circuit board layer, the moving counterweight is linked to the light source layer through the linkage component to move away from the light guide layer. Therefore, at the moment of impact, the light source layer is away from the light guide layer to avoid the light emitting body from being subjected to rigid impact, thereby protecting the light emitting body from damage.

[0019] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0020] This application document provides an overview of various implementations or examples of the technology described in the present disclosure, and is not a comprehensive disclosure of the entire scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0022] Figure 1 A schematic diagram of a front cross-sectional structure provided by an embodiment of the present invention;

[0023] Figure 2 The embodiment of the present invention provides Figure 1 A schematic diagram of the enlarged structure at A in the middle;

[0024] Figure 3 A schematic diagram of the overall structure provided by an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the internal structure of a bottom shell provided by an embodiment of the present invention;

[0026] Figure 5 The embodiment of the present invention provides Figure 4 A schematic diagram of the enlarged structure at B in the middle;

[0027] Figure 6 A schematic structural diagram of a bottom shell provided in an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 1. Bottom shell; 2. Top cover; 3. Circuit board layer; 4. Light source layer; 5. Light guide layer; 6. Display layer; 7. Light emitting body; 8. Counterweight; 9. Limit hook; 10. First elastic member; 11. Movable bin; 12. Second elastic member; 13. Lever; 14. Slide plate; 15. First sliding pin; 16. First sliding ring; 17. Linkage member; 18. Second sliding pin; 19. Second sliding ring; 20. Guide column; 21. Guide hole; 22. Support; 23. Screw; 24. Connector; 25. Screw hole. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0031] See also Figure 1-6 An electromagnetic digital screen provided by an embodiment of the present invention comprises a bottom shell 1 and a top cover 2, wherein a receiving cavity is formed between the bottom shell 1 and the top cover 2, wherein a circuit board layer 3, a light source layer 4, a light guide layer 5 and a display layer 6 are stacked in sequence from bottom to top in the receiving cavity, and further comprises: a light emitting body 7, wherein a plurality of light emitting bodies 7 are arranged in an array on the upper surface of the light source layer 4, and the upper end of the light emitting body 7 abuts against the light guide layer 5; the light source layer 4 is movably arranged, and a movable interval is reserved between the lower end and the circuit board layer 3; an inertia component, which is fixedly arranged in the receiving cavity and has a movable counterweight 8; a linkage component, which is used to link the counterweight 8 with the light source layer 4, wherein when the bottom shell 1 and the top cover 2 are impacted, the counterweight 8 moves under inertia and links the light source layer 4 through the linkage component to move away from the light guide layer 5.

[0032] Specifically, the bottom shell 1 and the top cover 2 are both arranged in a half-enclosed form, and when put together, they form an approximately rectangular shell structure; the accommodating cavity is the internal space of the shell structure composed of the bottom shell 1 and the top cover 2; the circuit board layer 3 integrates an integrated circuit board, a power supply, an interactive interface and a wiring harness, etc.; the light-emitting body 7 is offset from the light-guiding layer 5 to ensure the stability and quality of the light source; the movement of the light source layer 4, that is, the movement relative to the activity interval, can make the light-emitting body 7 and the light-guiding layer 5 reach a non-contact state; the inertia component is used to maintain the inertia of the counterweight 8 when the whole composed of the bottom shell 1 and the top cover 2 is impacted, so that the counterweight 8 moves relative to the bottom shell 1, and then the motion linkage can be generated through the linkage component; the linkage component is used to receive the movement of the counterweight 8 relative to the bottom shell 1, and then transmit the relative movement to affect the light source layer 4 to cause activity; when the counterweight 8 automatically maintains stillness relative to the bottom shell 1, the light source layer 4 is correspondingly located close to the light-guiding layer 5 to ensure the normal light source. In actual use of the present technical solution, when the bottom shell 1 and the top cover 2 are subjected to an impact such as falling, the counterweight 8 moves relative to the bottom shell 1 under the action of inertia. Also, since an active gap is reserved between the light source layer 4 and the circuit board layer 3, the relatively moving counterweight 8 links the light source layer 4 with the linkage assembly to move away from the light guide layer 5. As a result, at the moment of impact, the rigid impact on the bottom shell 1 and the top cover 2 will not be transmitted to the light source layer 4 through the light guide layer 5, and the light-emitting body 7 will not be subjected to a direct rigid impact, thereby protecting the light-emitting body 7 from damage.

[0033] Compared with the prior art, an electromagnetic digital screen proposed in an embodiment of the present invention is provided with an inertial component. When the bottom shell 1 and the top cover 2 are impacted, the counterweight 8 moves under inertia. Since an active gap is reserved between the light source layer 4 and the circuit board layer 3, the moving counterweight 8 is linked to the light source layer 4 through the linkage component to move away from the light guide layer 5. Therefore, at the moment of impact, the light source layer 4 is away from the light guide layer 5 to avoid the light-emitting body 7 from being subjected to rigid impact, thereby protecting the light-emitting body 7 from damage.

[0034] As a preferred technical solution of this embodiment, a limiting hook 9 is fixedly set on the inner side of the top cover 2, and the limiting hook 9 limits the light guide layer 5 and the display layer 6 to be set close to the inner wall of the top cover 2. Specifically, the setting of the limiting hook 9 makes the light guide layer 5 and the display layer 6 close to the inner top surface of the top cover 2 after installation, that is, the light guide layer 5 and the display layer 6 are limited to be relatively fixed in the accommodating cavity and are not affected by the movable light source layer 4.

[0035] As a preferred technical solution of this embodiment, a plurality of first elastic members 10 are evenly arranged between the inner bottom surface of the bottom shell 1 and the light source layer 4. The first elastic members 10 maintain elasticity to push the light source layer 4 upward. Specifically, the first elastic member 10 may preferably be a spring. The plurality of first elastic members 10 may be relatively arranged at the four corners of the light source layer 4. The setting of the first elastic members 10 keeps pushing the light source layer 4 upward so that the light source layer 4 remains in contact with the light guide layer 5.

[0036] As the preferred technical solution of this embodiment, the inertial component includes a movable bin 11 fixedly connected to the inner bottom surface of the bottom shell 1, the counterweight 8 is slidably arranged in the movable bin 11 and second elastic members 12 are arranged at both ends to counteract the inner top surface and inner bottom surface of the movable bin 11. Specifically, the movable bin 11 is arranged on the side close to the bottom shell 1 and is arranged perpendicular to the inner bottom surface of the bottom shell 1; the counterweight 8 moves freely in the movable bin 11, but the two ends of the moving direction are respectively affected by a second elastic member 12; the second elastic member 12 may preferably be a spring, and the setting of the second elastic member 12 automatically maintains the counterweight 8 in the middle position of the movable range in the movable bin 11; the stacking direction of the light source layer 4 and the light guide layer 5 is parallel to the moving direction of the counterweight 8, which can better realize the triggering in the stacking direction of the light source layer 4 and the light guide layer 5, and when an impact occurs on the bottom shell 1 and the top cover 2 in a direction perpendicular to the above stacking direction, that is, the light source layer 4 and the light guide layer 5 are impacted in a direction parallel to them, at this time, the damage to the light-emitting body 7 on the light source layer 4 may be extremely small.

[0037] As the preferred technical solution of this embodiment, the linkage assembly includes a lever 13 rotatably arranged on the inner bottom surface of the bottom shell 1 and a slide plate 14 movably arranged on the outer wall of the movable bin 11, a first sliding pin 15 movably penetrating the movable bin 11 is arranged on the counterweight 8, a first sliding ring 16 slidably connected to the first sliding pin 15 is arranged at one end of the lever 13, a linkage member 17 is slidably arranged on the slide plate 14, a side wall of the linkage member 17 is hinged to the other end of the lever 13, a second sliding pin 18 is fixedly arranged on the side wall of the slide plate 14, and a first sliding ring 16 slidably connected to the first sliding pin 15 is arranged on the side of the light source layer 4. The second sliding ring 19 is slidably connected to the second sliding pin 18. Specifically, a guide column 20 is fixedly provided on the outer wall of the movable bin 11 on the side close to the light source layer 4, and a guide hole 21 matching the guide column 20 is provided on the slide plate 14; the guide column 20 points from the movable bin 11 to the light source layer 4; the guide column 20 can preferably be two, arranged at both ends along the extension direction of the movable bin 11, and the slide plate 14 is arranged between the light source layer 4 and the movable bin 11, and moves close to or away from the side wall of the movable bin 11; the part of the first sliding pin 15 that passes through the movable groove 1 is set The length direction of the first sliding pin 15 is perpendicular to the movable direction of the counterweight 8, and the length direction of the first sliding pin 15 is parallel to the side of the light source layer 4; a support 22 is fixedly arranged on the inner bottom surface of the bottom shell 1, and the middle position of the lever 13 is hinged at the upper end of the support 22; the axial direction of the lever 13 is parallel to the length direction of the first sliding pin 15, and the rotating shaft of the lever 13 is arranged between the movable bin 11 and the slide plate 14; the setting of the first sliding ring 16 is used to ensure that the movement of the first sliding pin 15 driven by the counterweight 8 is linked to the rotation of the lever 13, and avoid To avoid interference between the two; the linkage member 17 is clamped on the skateboard 14 and moves along the length direction of the skateboard 14, and the linkage member 17 is arranged on the side of the skateboard 14 away from the light source layer 4; the hinge axis of the linkage member 17 and the lever 13 is arranged parallel to the rotation axis of the lever 13; the setting of the linkage member 17 makes the rotation of the lever 13 and the movement of the skateboard 14 relative to the movable warehouse 11 linked, and avoid interference between the two; when the counterweight 8 is in the automatic static position, one end of the lever 13 is hinged to the linkage member 17, so that the skateboard 14 is kept at the farthest position from the movable warehouse 11. An extension portion is provided on the side of the slide plate 14 close to the light source layer 4, and the second sliding pin 18 is provided at the farthest end of the extension portion; the second sliding ring 19 is inclined upward at one end close to the movable warehouse 11; when the slide plate 14 approaches the movable warehouse 11, the second sliding pin 18 slides toward the higher end of the second sliding ring 19 to make this end of the light source layer 4 move away from the light guiding layer 5; when the slide plate 14 moves away from the movable warehouse 11, the second sliding pin 18 slides toward the lower end of the second sliding ring 19 to make this end of the light source layer 4 move closer to the light guiding layer 5.

[0038] In actual use of the above technical solution, when the bottom shell 1 and the top cover 2 fall as a whole, causing the counterweight 8 to move under inertia, the counterweight 8 resists the second elastic member 12 to move relatively in the movable bin 11. At the same time, the counterweight 8 drives the first sliding pin 15 to move, and the first sliding pin 15 moves relatively with the first sliding ring 16 to rotate the linkage lever 13. When the lever 13 rotates, the other end drives the linkage member 17 to slide relatively on the slide plate 14, and drives the linkage member 17 and the slide plate 14 to move closer to the movable bin 11. Therefore, the slide plate 14 drives the second sliding pin 15 to move relatively with the first sliding ring 16. 8 moves so that the second sliding pin 18 slides toward the higher end of the second sliding ring 19, thereby causing this end of the light source layer 4 to move away from the light guiding layer 5, thereby preventing the light-emitting body 7 on the light source layer 4 from being subjected to direct rigid impact and pressure at the moment of impact; subsequently, when the fall is over, the counterweight 8 is reset under the action of the second elastic member 12, and the lever 13 is also rotated and reset, and then the slide plate 14 is away from the movable warehouse 11 again, thereby driving the second sliding pin 18 to slide toward the lower end of the second sliding ring 19, thereby causing this end of the light source layer 4 to move closer to the light guiding layer 5, even if the light source layer 4 and the light guiding layer 5 are close to each other again.

[0039] In another embodiment of the present invention, the part where the bottom shell 1 and the top cover 2 are connected is wedge-shaped, and the side wall of the bottom shell 1 is provided with a locking component for fixing the top cover 2. Specifically, a chamfer is provided on the inner side of the upper end of the bottom shell 1, and a chamfer is provided on the outer side of the lower end of the top cover 2. The bottom shell 1 and the top cover 2 are wedge-shapedly matched with each other through the chamfers, and then a locking component is provided on the side wall of the bottom shell to achieve mutual docking connection between the bottom shell 1 and the top cover 2. On the one hand, the sealing is ensured, and on the other hand, the traditional clamping structure is no longer used, and there is no need to pry it open with a prying piece or other tools during disassembly to avoid surface damage. , affecting the subsequent sealing performance; the bent parts of the bottom shell 1 and the top cover 2 are at least made of a material with bending elasticity. On the one hand, they can be directly used for cushioning at the corners when falling. On the other hand, when the corners are impacted, the elastic bent parts can bend, and under the wedge-shaped cooperation of the bottom shell 1 and the top cover 2, the wedge-shaped surfaces of the two are squeezed against each other, and then the impact directly occurring on the bottom shell 1 or the top cover 2 can be transmitted to the top cover 2 or the bottom shell 1, so that the bent parts of the two can generate elasticity to fully resist the impact, thereby achieving uniform force on the impact and increasing the drop resistance.

[0040] As a preferred technical solution of this embodiment, the locking assembly includes a screw 23 that movably penetrates the side wall of the bottom shell 1, and a connecting piece 24 extending downward is provided on the inner side wall of the top cover 2. The connecting piece 24 is provided with a screw hole 25 that matches the screw 23. Specifically, 3-5 screws 23 are preferably provided on the same side of the bottom shell 1; a through hole is provided on the side wall of the bottom shell 1 for the screw 23 to pass through; a surrounding piece is provided on the inner side of the bottom shell 1 corresponding to the position where the screw 23 passes through, and the surrounding piece corresponds to the connecting piece 24 one by one, and the top cover 2 and the bottom shell 1 are aligned. When connected, the lower end of the connecting piece 24 can be inserted into the surrounding piece, and the screw hole 25 on the connecting piece 24 corresponds to the through hole on the side wall of the bottom shell 1. Subsequently, the screw 23 can pass through and be screwed with the screw hole 25, thereby fixing the top cover 2 and the bottom shell 1 relatively; further, a gap is left between the connecting piece 24 and the inner wall of the bottom shell 1. When the screw 23 is tightened, the gap can cause the connecting piece 24 to deform slightly and approach the inner wall of the bottom shell 1, thereby squeezing the wedge-shaped mating surfaces of the bottom shell 1 and the top cover 2 tightly, thereby enhancing the sealing.

[0041] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An electromagnetic digital display, comprising a bottom shell (1) and a top cover (2), wherein a receiving cavity is formed between the bottom shell (1) and the top cover (2), and a circuit board layer (3), a light source layer (4), a light guide layer (5) and a display layer (6) are stacked in sequence from bottom to top in the receiving cavity, characterized in that: Also includes: A plurality of illuminants (7) are arranged in an array on the upper surface of the light source layer (4), with the upper ends of the illuminants abutting against the light guide layer (5); the light source layer (4) is movably arranged, and a movable gap is left between the lower end and the circuit board layer (3); An inertial component, which is fixedly arranged in the accommodating cavity and has a movable counterweight (8); A linkage component is used to link the counterweight (8) and the light source layer (4), and when the bottom shell (1) and the top cover (2) are impacted, the counterweight (8) moves under inertia and links the light source layer (4) through the linkage component to move away from the light guide layer (5); The inertia component comprises a movable bin (11) fixedly connected to the inner bottom surface of the bottom shell (1), the counterweight (8) is slidably arranged in the movable bin (11) and second elastic members (12) are arranged at both upper and lower ends to abut against the inner top surface and inner bottom surface of the movable bin (11); The linkage assembly comprises a lever (13) rotatably arranged on the inner bottom surface of the bottom shell (1) and a slide plate (14) movably arranged on the outer wall of the movable bin (11); the counterweight (8) is provided with a first sliding pin (15) movably penetrating the movable bin (11); one end of the lever (13) is provided with a first sliding ring (16) slidably connected to the first sliding pin (15); a linkage member (17) is slidably arranged on the slide plate (14); the side wall of the linkage member (17) is hinged to the other end of the lever (13); a second sliding pin (18) is fixedly arranged on the side wall of the slide plate (14); and a second sliding ring (19) slidably connected to the second sliding pin (18) is provided on the side of the light source layer (4).

2. The electromagnetic digital display according to claim 1, characterized in that: A limiting hook (9) is fixedly arranged on the inner side of the top cover (2), and the limiting hook (9) limits the light guide layer (5) and the display layer (6) to be arranged close to the inner wall of the top cover (2).

3. The electromagnetic digital display according to claim 1, characterized in that: A plurality of first elastic members (10) are evenly arranged between the inner bottom surface of the bottom shell (1) and the light source layer (4), and the first elastic members (10) maintain elasticity to push the light source layer (4) upwards.

4. The electromagnetic digital display according to claim 1, characterized in that: A guide column (20) is fixedly provided on the outer side wall of the movable chamber (11) on the side close to the light source layer (4), and a guide hole (21) matching the guide column (20) is provided on the slide plate (14).

5. The electromagnetic digital display according to claim 1, characterized in that: A support (22) is fixedly arranged on the inner bottom surface of the bottom shell (1), and the middle position of the lever (13) is hinged to the upper end of the support (22).

6. The electromagnetic digital display according to claim 1, characterized in that: One end of the second sliding ring (19) close to the movable bin (11) is arranged to be inclined upward.

7. The electromagnetic digital display according to claim 1, characterized in that: The part where the bottom shell (1) and the top cover (2) are connected is arranged in a wedge-shaped manner, and the side wall of the bottom shell (1) is provided with a locking component for fixing the top cover (2).

8. The electromagnetic digital display according to claim 7, characterized in that: The locking assembly comprises a screw (23) movably penetrating the side wall of the bottom shell (1); the inner side wall of the top cover (2) is provided with a connecting piece (24) extending downward; and the connecting piece (24) is provided with a screw hole (25) matching the screw (23).

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