Modularized electromagnetic shielding atomizer

Abstract

According to the modularized electromagnetic shielding atomizer, when a shell is made of conductive plastic and the volume resistivity range of the shell is 10 omega.m to 10 kilomega.m, the index requirements of EMI and MEC can be met, that is, the index requirements of conduction and radiation or power disturbance are met, and meanwhile, the requirements of heat transfer and heat dissipation can be met, so that the modular electromagnetic shielding atomizer has the advantages that the structure is simple, the cost is low, and the application range is wide. Therefore, the requirements of the shielding function and the heat dissipation function of the product can be met with relatively low cost, and the competitiveness of the product is greatly improved while the structural limitation and the material limitation of the metal shell are solved. And on the other hand, the conductive plastic container with a modular nested structure and a double-cavity structure, the metal surface of the driving circuit board and the conductive plastic gland are grounded through metal screws to form a closed-loop shielding body, so that the electromagnetic shielding effect is achieved, the automatic assembly efficiency is improved to 1800 pieces per hour (less than or equal to 400 pieces per hour in the traditional process), and the labor cost is reduced by 83%.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic atomization, and more specifically, relates to a modular electromagnetic shielding atomizer. Background Art

[0002] As a core device that uses high-frequency vibrations to convert liquids into tiny droplets, nebulizers are widely used in scenarios such as medical aerosol drug delivery, industrial spray cooling, and smart home humidification. Piezoelectric nebulizers have become mainstream due to their high energy conversion efficiency and uniform atomized particles. Their core component, the atomizer (piezoelectric ceramic transducer), converts high-frequency electrical energy into high-frequency mechanical vibrations of approximately 1.7MHz or 2.4MHz through the inverse piezoelectric effect, achieving liquid atomization. High-frequency electrical energy emits electromagnetic radiation, requiring the nebulizer to be properly electromagnetically shielded to prevent interference with other electronic devices.

[0003] Existing electromagnetic shielding atomizers use metal casings for electromagnetic shielding. However, in the application of high-frequency oscillation circuits (whether self-excited or externally excited), there are irreconcilable technical contradictions, as shown in Table 1:

[0004] Contradictory dimensions Technical requirements Metallic solutions drawbacks Electromagnetic compatibility (EMC) Shielding effectiveness > 60 dB (300 MHz) Junctions prone to slot antenna effect Thermal management Thermal resistance <1.5℃ / W Dependence on thermal grease to fill interface thermal resistance Environmental suitability Salt spray resistance > 48 h The anodic oxide layer fails in an environment with pH < 5 Manufacturing costs Material cost accounts for <30% High cost of composite processing

[0005] Table 1

[0006] This has two limitations:

[0007] A. Structural limitations: The metal cavity needs to maintain electrical continuity, resulting in:

[0008] * Machining must be used to ensure flatness (flatness requirement ≤ 0.1mm / m);

[0009] *Fasteners need to be gold plated to prevent electrochemical corrosion.

[0010] B. Material limitations:

[0011] *Aluminum alloy density 2.7g / cm 3 Causes the portable device to exceed the weight limit (e.g. medical handheld devices are required to be less than 150g);

[0012] *The thermal conductivity of stainless steel is only 15W / (m·K), requiring additional heat dissipation structure.

[0013] The industry has explored non-metallic solutions but all have failed, including:

[0014] Engineering plastics: Although they can be injection molded (such as PPS), their volume resistivity is greater than 1012Ω·m and cannot form electromagnetic shielding.

[0015] Surface metallization: The chemical nickel plating layer is easy to peel off under ultrasonic vibration (vibration frequency 1.7MHz accelerates failure);

[0016] Conductive coating: Uneven coating thickness causes shielding effectiveness fluctuations >20dB (measured data).

[0017] In addition, in existing electromagnetic shielding atomizers, the piezoelectric ceramic sheet assembly and the driving circuit board are assembled separately, and there is a lack of precise coordination between the components, which makes the automated assembly efficiency low and the labor cost high. Summary of the Invention

[0018] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a modular electromagnetic shielding atomizer. On the one hand, it solves the structural and material limitations of the metal shell. On the other hand, it uses a modular nested structure to improve the efficiency of automated assembly and reduce labor costs.

[0019] To achieve the above-mentioned object of the invention, the modular electromagnetic shielding atomizer of the present invention is characterized in that the shell is made of conductive plastic with a volume resistivity ranging from 10Ω·m to 10kΩ·m.

[0020] As a further improvement, the base material of the conductive plastic is polyetheretherketone (PEEK), and the filler is 3-5 wt% of carbon nanotubes (CNT) and 15-20 wt% of nickel-coated graphite powder (Ni / C).

[0021] As a further improvement, the housing includes a conductive plastic gland and a conductive plastic container with a dual-cavity structure. The conductive plastic container with a dual-cavity structure includes a driving circuit board cavity and an atomizing plate cavity, which are used to place the driving circuit board and the atomizing plate respectively.

[0022] The driver circuit board has a metal surface on one side and a circuit surface on the other side, where circuit traces and components are mounted.

[0023] The driving circuit board and the conductive plastic container have through holes, and metal screws are used to pass through the through holes of the driving circuit board and the through holes of the conductive plastic container in turn and fasten them to the conductive plastic pressure cover. The circuit surface of the driving circuit board faces inward and the metal surface faces outward. The metal screws are conductive to the metal surface, and the metal surface is connected to the conductive plastic pressure cover through the metal screws to form a shielding layer, which seals the driving circuit board in the driving circuit board cavity; there is an atomizer power supply line through hole between the driving circuit board cavity and the atomizer cavity of the conductive plastic container, which is used to connect the driving circuit board and the atomizer. The center of the conductive plastic pressure cover is the atomization port, and its edge is tightly pressed against the edge of the atomizer so that the exposed surface of the central part of the atomizer can contact the water to atomize the water, and at the same time, it also plays a shielding role.

[0024] The object of the invention of the present invention is achieved like this:

[0025] The modular electromagnetic shielding atomizer of the present invention, when the outer shell is made of conductive plastic with a volume resistivity ranging from 10Ω·m to 10kΩ·m, can not only meet the index requirements of EMI and MEC, that is, meet the index requirements of conduction and radiation or power interference, but also meet the requirements of heat transfer and heat dissipation. In this way, the product's shielding and heat dissipation functions can be achieved at a relatively low cost, solving the structural and material limitations of the metal outer shell while greatly improving the competitiveness of the product. On the other hand, a modular nested structure is further adopted. The conductive plastic container with a double-cavity structure, the metal surface of the drive circuit board, and the conductive plastic pressure cover are grounded by metal screws to form a closed-loop shielding body. While achieving the electromagnetic shielding effect, it also increases the efficiency of automated assembly to 1,800 units / hour (traditional process ≤400 units / hour), reducing labor costs by 83%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is an exploded view of a specific embodiment of the modular electromagnetic shielding atomizer of the present invention, wherein (a) is placed upright, and (b) is placed inverted;

[0027] Figure 2 yes Figure 1 The conductive plastic gland structure shown in FIG, wherein (a) is the upper surface and (b) is the lower surface;

[0028] Figure 3 yes Figure 1 The structural diagram of the piezoelectric ceramic sheet assembly shown, wherein (a) is the upper surface and (b) is the lower surface;

[0029] Figure 4 yes Figure 1 The structural diagram of the conductive plastic container with a dual-cavity structure shown, wherein (a) is the upper surface and (b) is the lower surface;

[0030] Figure 5 yes Figure 1 The structural diagram of the driving circuit board shown, wherein (a) is the upper surface and (b) is the lower surface;

[0031] Figure 6 yes Figure 1 The structure diagram of the modular electromagnetic shielding atomizer after assembly, wherein (a) is placed upright, and (b) is placed inverted;

[0032] Figure 7 yes Figure 6 A cross-sectional view of the assembled modular electromagnetic shielding atomizer is shown. DETAILED DESCRIPTION

[0033] The following describes the specific embodiments of the present invention in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when detailed descriptions of known functions and designs may dilute the main content of the present invention, such descriptions will be omitted here.

[0034] The shell of the modular electromagnetic shielding atomizer of the present invention is made of conductive plastic with a volume resistivity ranging from 10Ω·m to 10kΩ·m, which can meet the absorption loss dominant mechanism (when the thickness d=3mm):

[0035]

[0036] in:

[0037]

[0038] Table 2

[0039] And at the same time satisfy the heat conduction equation:

[0040] Satisfy λ≥1.5W / (m·k)Δt≤40℃ (2)

[0041] in:

[0042]

[0043] Table 3

[0044] When we formulate conductive plastic with a suitable volume resistivity according to the above formula and injection mold it into the shape we design, this product not only meets the EMI and MEC index requirements, that is, the index requirements for conduction and radiation or power interference; at the same time, the product can also meet the requirements of heat transfer and heat dissipation. In this way, the shielding and heat dissipation functions required by the product can be achieved at a relatively low cost, while solving the structural and material limitations of the metal casing and greatly improving the competitiveness of the product.

[0045] 1. Application scenario verification

[0046] Typical atomizer EMC test data are as follows:

[0047] Shielding solutions 30 MHz radiation value (dBpV / m) Compliance (Class B) No shielding 71.3 Fail Traditional aluminum alloy enclosure 36.5 Pass <![CDATA[本发明(ρ=10 3 Ohm)]]> 38.9 Pass (A = 37.2 dB) <![CDATA[本发明(ρ=10 4 Ohm)]]> 41.7 Marginal pass

[0048] Table 4

[0049] Note: ρ = 10 4 The Ω·m solution exceeded the safety threshold once in three tests (42.1dBμV / m), proving that 35dB is the lower limit of the safety threshold.

[0050] Conclusion: 35dB is the optimal solution that balances regulatory compliance, material feasibility, and cost controllability. 1. Below this value → EMC certification failure risk > 30% (actual measurement statistics); 2. Above this value → material costs surge by more than 50% (carbon filler needs to be > 20wt%).

[0051] 2. Experimental verification data

[0052] Test standards:

[0053] Electromagnetic shielding: IEC 62333-2:2006

[0054] Thermal conductivity: ASTM D5470

[0055] Summary of results:

[0056] Conductive plastic types Volume resistivity (Q-m) 2.4 MHz shielding effectiveness (dB) Thermal conductivity (W / m-K) CNT / PEEK composite 8.2 71.3 2.1 Ni / C-PPS composite <![CDATA[4.5×10 2 ]]> 53.6 1.8 Graphene / PA66 9.8 x 10 3 ]] 39.2 1.53 Suitable range <![CDATA[10-10 4 ]]> ≥35 ≥1.5

[0057] Table 5

[0058] The resistivity threshold of conductive plastics is the key to success: when ρ < 10Ω·m, the mechanical strength is insufficient; when ρ > 10kΩ·m, the shielding effectiveness is < 35dB (failure in actual measurement); only the 10Ω·m-10kΩ·m range can simultaneously meet EMC, thermal management and injection moldability.

[0059] In the specific implementation process, preferably, the base material of the conductive plastic is polycarbonate (PC), and the filler is 20wt% nickel-coated carbon brazing (such as RTP 385HEC), or the base material of the conductive plastic is ABS, and the filler is 15wt% carbon brazing (such as DS-AB superconducting type), or the base material of the conductive plastic is polyamide (PA), and the filler is 30wt% carbon brazing.

[0060] In this embodiment, if Figure 1 As shown, as a further improvement, the housing includes a conductive plastic gland 1 and a dual-chamber conductive plastic container 3. The dual-chamber conductive plastic container 3 includes a driver circuit board cavity CC and an atomizer cavity AC, which are respectively used to accommodate the driver circuit board 4 and the atomizer 201. In this embodiment, the atomizer 201 is a piezoelectric ceramic plate, which is placed in a silicone protective sleeve 202 to form a piezoelectric ceramic plate assembly 2.

[0061] In this embodiment, if Figure 2As shown in (a), the conductive plastic gland 1 is a circular structure, including a circular atomization port 101 located in the center, a plurality of (four in this embodiment) fastening screw holes 102 located on the outermost side and evenly distributed with the center of the circle as the center for connecting to the water tank, and a circular protrusion 103 is provided on the upper surface between the circular atomization port 101 and the fastening screw holes 102. The circular protrusion 103 is covered with a silicone ring 104 on the upper surface. When the water tank is connected, the water tank is covered with the circular protrusion 103, and the bottom of the water tank is pressed against the silicone ring 104 to prevent the water inside from leaking out; in this embodiment, as shown in FIG. Figure 2 As shown in (b), four positioning posts 105 are evenly distributed at positions corresponding to the circular protrusion 103 on the lower surface of the conductive plastic gland 1. The positioning posts 105 have screw holes for fastening metal screws. A groove 106 with a rectangular cross-section is provided between the four positioning posts 105 on the lower surface of the conductive plastic gland 1 and the circular atomization port 101.

[0062] In this embodiment, if Figure 3 As shown in (a), the piezoelectric ceramic piece assembly 2 consists of an atomizing piece 201 and a silicone protective cover 202. The silicone protective cover 202 is a cylindrical structure with a cylindrical groove in the middle for placing the atomizing piece 201. The thickness of the cylindrical groove wall 2021 is consistent with the thickness of the groove 106 on the lower surface of the conductive plastic gland 1. During assembly, the cylindrical groove wall 2021 is placed in the groove 106, so that the edge of the circular atomizing port 101 is tightly pressed against the edge of the atomizing piece 201 through the silicone protective cover 202. In this embodiment, as shown in FIG. Figure 3 As shown in (b), there is a silicone positioning step 2022 on the lower surface of the silicone protective cover 202. The power supply line 2011 of the atomizer 201 passes through the bottom of the silicone protective cover 202, comes out from the silicone positioning step 2022, and is tightly combined with the silicone protective cover 202 to prevent water leakage.

[0063] In this embodiment, if Figure 4 As shown in (a), the conductive plastic container 3 with a dual-cavity structure is a square structure with a through hole at each of the four corners, wherein the through hole on one side of the atomizer cavity AC is a stepped through hole 301. During assembly, the positioning post 105 of the conductive plastic gland 1 is nested in the stepped through hole 301, fixed in position and the top surface of the positioning post 105 is in contact with the stepped surface of the stepped through hole 301. The atomizer cavity AC of the conductive plastic container 3 with a dual-cavity structure is a circular groove, the shape and size of which are consistent with the bottom of the silicone protective cover 202, ensuring that the silicone protective cover 202 is not deformed due to excessive pressure. There is an atomizer power supply line through hole 302 at the bottom of the circular groove, which is used to connect the drive circuit board cavity CC and the atomizer cavity AC. Its shape is consistent with the silicone positioning step 2022. During assembly, the silicone positioning step 2022 is nested in the atomizer power supply line through hole 302 for positioning and fixing.

[0064] In this embodiment, ifFigure 4 (b) As shown, the through hole of the drive circuit board cavity CC side of the double-cavity structure conductive plastic container 3 is a hollow screw column 303, which is provided with a circuit board limiting convex ring, the height of the circuit board limiting convex ring is lower than the thickness of the drive circuit board 4, in this embodiment, 0.2-0.8mm lower, and the outer diameter is smaller than the through hole of the drive circuit board 4, in this embodiment, 0.2-0.8mm smaller, when assembled, the circuit surface of the drive circuit board 4 faces inward, the metal surface faces outward and is placed on the circuit board limiting convex ring, forming a shielding cavity with the drive circuit board cavity CC;

[0065] In this embodiment, as shown in Figure 5 , the drive circuit board 4 is a one-side metal surface 401 and the other side is a circuit surface 402, the circuit surface 402 is provided with circuit traces and mounted components, and when assembled, the drive circuit board 4 is connected with the power supply wire 2011 of the atomizing piece 201. In this embodiment, the drive circuit board 4 is a square structure, and the size is consistent with the drive circuit board cavity CC, so that the drive circuit board 4 and the drive circuit board cavity CC form a closed shielding space. The drive circuit board 4 has a through hole 403 at each of the four corners. In this embodiment, as shown in Figure 1 , a metal screw 5 is used to pass through the through hole 403 of the drive circuit board 4, the through hole of the conductive plastic container, i.e. the hollow screw column 303, and the stepped through hole 301 in sequence, and is fastened to the positioning column 105 of the conductive plastic gland 1, the circuit surface 402 of the drive circuit board 4 faces inward, the metal surface 401 faces outward, the metal screw 5 is in conduction with the metal surface 401, the metal surface 401 is in communication with the conductive plastic gland 1 through the metal screw 5, forming a shielding layer, and the drive circuit board 4 is closed in the drive circuit board cavity CC; the drive circuit board cavity CC and the atomizing piece cavity CA of the conductive plastic container 3 have an atomizing piece power supply wire through hole 302 for connecting the drive circuit board 4 and the atomizing piece 201, and the center of the conductive plastic gland 1 is an atomizing port, the edge thereof is tightly pressed against the edge of the atomizing piece 201 by the silica gel protective sleeve 202, so that the exposed surface of the central part of the atomizing piece 201 is in contact with water to atomize the water, and at the same time, a certain shielding effect is also achieved.

[0066] The assembled modular electromagnetic shielding atomizer is as shown in Figure 6 , the conductive plastic container, the metal surface of the drive circuit board and the conductive plastic gland form a closed loop shielding body through the metal screw. The cross-sectional view is as shown in Figure 7 , all components are modular nested structures, tightly matched, compact structure, and convenient for automatic assembly.

[0067] The present application breaks through the three major pain points in the industry:

[0068] 1. Material substitution revolution

[0069] Conductive plastics integrate the dual functions of heat dissipation and shielding into the metal housing, reducing weight by 42% (measured data). Their salt spray resistance reaches level 9 for 96 hours per GB / T2423.17-2008. Furthermore, they offer the following advantages:

[0070] a. The molding and processing of metal shells is complicated, secondary processing accounts for a large proportion, processing energy consumption is high, and the production cycle is long. However, in the present invention, the conductive plastic has low processing cost, is injection molded in one step, and has a short production cycle;

[0071] b. The surface of the ultrasonic atomizing head needs to be in contact with water. If the metal shell needs to be corrosion-resistant, it needs surface treatment to prevent corrosion. However, in the present invention, the conductive plastic is resistant to salt spray corrosion and does not require additional protection;

[0072] c. Under the same volume, the weight of conductive plastic is about 50%-60% of aluminum alloy;

[0073] d. Fine structure plastics are easier to shape.

[0074] 2. EMC design innovation

[0075] By controlling the resistivity of conductive plastic (10Ω-10kΩ), we optimize electromagnetic wave absorption loss and combine it with cavity resonance suppression technology to achieve the following results in one go:

[0076] EN55022 Class B radiated disturbance limits;

[0077] EN61000-4-310V / m radio frequency field immunity.

[0078] 3. Production paradigm upgrade

[0079] All components are modular and nested, forming a modular assembly process. Visual mechanical equipment can be used for large-scale production, increasing the efficiency of automated assembly to 1,800 units / hour (traditional process ≤ 400 units / hour) and reducing labor costs by 83%.

[0080] Although the above describes the illustrative specific embodiments of the present invention to facilitate understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concepts of the present invention are protected.

Claims

1. A modular electromagnetic shielding atomizer, characterized in that: The housing is made of conductive plastic with a volume resistivity range of 10Ω·m to 10kΩ·m.

2. The modular electromagnetic shielding atomizer according to claim 1, characterized in that: The base material of the conductive plastic is polyetheretherketone, and the filler is 3-5wt% of carbon nanotubes and 15-20wt% of nickel-coated graphite powder.

3. The modular electromagnetic shielding atomizer according to claim 1, characterized in that: The base material of the conductive plastic is polycarbonate, and the filler is 20 wt% of nickel-coated carbon fiber.

4. The modular electromagnetic shielding atomizer according to claim 1, characterized in that: The base material of the conductive plastic is ABS, and the filler is 15 wt% of carbon fiber.

5. The modular electromagnetic shielding atomizer according to claim 1, characterized in that: The base material of the conductive plastic is polyamide, and the filler is 30 wt% of carbon fiber.

6. The modular electromagnetic shielding atomizer according to claim 1, characterized in that: The housing includes a conductive plastic gland and a conductive plastic container with a dual-cavity structure. The conductive plastic container with a dual-cavity structure includes a driving circuit board cavity and an atomizing plate cavity, which are used to place the driving circuit board and the atomizing plate respectively. The driver circuit board has a metal surface on one side and a circuit surface on the other side, where circuit traces and components are mounted. The driving circuit board and the conductive plastic container have through holes, and metal screws are used to pass through the through holes of the driving circuit board and the through holes of the conductive plastic container in turn and fasten them to the conductive plastic pressure cover. The circuit surface of the driving circuit board faces inward and the metal surface faces outward. The metal screws are conductive to the metal surface, and the metal surface is connected to the conductive plastic pressure cover through the metal screws to form a shielding layer, which seals the driving circuit board in the driving circuit board cavity; there is an atomizer power supply line through hole between the driving circuit board cavity and the atomizer cavity of the conductive plastic container, which is used to connect the driving circuit board and the atomizer. The center of the conductive plastic pressure cover is the atomization port, and its edge is tightly pressed against the edge of the atomizer so that the exposed surface of the central part of the atomizer can contact the water to atomize the water, and at the same time, it also plays a shielding role.

7. The modular electromagnetic shielding atomizer according to claim 6, characterized in that: The conductive plastic gland is a circular structure, including a circular atomization port in the center, a plurality of fastening screw holes located on the outermost side and evenly distributed with the center of the circle as the center for connecting to the water tank, and a circular ring protrusion on the upper surface between the circular atomization port and the fastening screw holes. Four positioning columns are evenly distributed at corresponding positions of the circular ring protrusion on the lower surface of the conductive plastic gland, and the positioning columns have screw holes for fastening metal screws. There is a circular ring-shaped groove with a rectangular cross-section between the four positioning columns on the lower surface of the conductive plastic gland and the circular atomization port.

8. The modular electromagnetic shielding atomizer according to claim 7, characterized in that: The piezoelectric ceramic piece assembly consists of an atomizer and a silicone protective cover. The silicone protective cover is a cylindrical structure with a cylindrical groove in the middle for placing the atomizer. The thickness of the cylindrical groove wall is consistent with the thickness of the groove on the lower surface of the conductive plastic gland. During assembly, the cylindrical groove wall is placed in the groove. There is a silicone positioning step on the lower surface of the silicone protective cover. The power supply line of the atomizer passes through the bottom of the silicone protective cover, passes out from the silicone positioning step, and is tightly combined with the silicone protective cover to prevent water leakage.

9. The modular electromagnetic shielding atomizer according to claim 8, characterized in that: The conductive plastic container with a dual-cavity structure is a square structure with a through hole at each of the four corners. The through hole on one side of the atomizer cavity is a stepped through hole. During assembly, the positioning post of the conductive plastic gland is nested in the stepped through hole, fixing the position and the top surface of the positioning post contacts the stepped surface of the stepped through hole. The atomizer cavity of the conductive plastic container with a dual-cavity structure is a circular groove, the shape and size of which are consistent with the bottom of the silicone protective cover, ensuring that the silicone protective cover is not deformed due to excessive pressure. There is a through hole for the atomizer power supply line at the bottom of the circular groove, which is used to connect the driver circuit board cavity and the atomizer cavity. Its shape is consistent with the silicone positioning step. During assembly, the silicone positioning step is nested in the through hole for the atomizer power supply line for positioning and fixing. The through hole on one side of the driving circuit board cavity of the conductive plastic container with a dual-cavity structure is a hollow screw column, on which a circuit board limiting convex ring is provided. The height of the circuit board limiting convex ring is lower than the thickness of the driving circuit board, and the outer diameter is smaller than the through hole of the driving circuit board. During assembly, the circuit surface of the driving circuit board faces inward, and the metal surface faces outward and is placed on the circuit board limiting convex ring, forming a shielding cavity with the driving circuit board cavity.

10. The modular electromagnetic shielding atomizer according to claim 9, characterized in that: The driver circuit board has a metal surface on one side and a circuit surface on the other. The circuit surface is used for circuit routing and mounting components. During assembly, the driver circuit board is connected to the power supply line of the atomizer. There is a through hole at each of the four corners of the driver circuit board. Metal screws are used to pass through the through hole of the driver circuit board, the through hole of the conductive plastic container, i.e. the hollow screw column, and the stepped through hole in sequence, and fastened to the positioning column of the conductive plastic pressure cover. The circuit surface of the driver circuit board faces inward and the metal surface faces outward. The metal screws are connected to the metal surface, and the metal surface is connected to the conductive plastic pressure cover through the metal screws to form a shielding layer, which seals the driver circuit board in the driver circuit board cavity.

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