Electrostatic filter

Abstract

The application discloses an electrostatic filter, and belongs to the field of electrostatic filters. The electrostatic filter comprises an outer frame, a filter screen assembly arranged in the outer frame and forming an air passing channel, and an electrode assembly. The electrode assembly comprises first electrode sheets and second electrode sheets arranged alternately. The first electrode sheets and the second electrode sheets are arranged oppositely to form a plurality of electric field gaps, and are electrically connected to different polarity ends of an external high-voltage power supply respectively. A weakly-conductive covering layer is arranged on the outer surface of the conductive electrode layer to form a first surface resistivity area and a second surface resistivity area at the edge. The charge discharge rate from the edge to the inner side changes in a controlled gradient, thereby solving the problems of abnormal discharge and rising leakage current caused by the charge stacking at the edge.

Description

Technical Field

[0001] This invention relates to the field of electrostatic filter technology, and more specifically, to an electrostatic filter. Background Technology

[0002] Electrostatic filtration technology is widely used in air purifiers, fresh air systems, industrial dust removal, and fume purification due to its high efficiency in capturing fine particulate matter, relatively low air resistance, and suitability for circulating purification. Existing electrostatic filters typically use an external high-voltage power supply to create an electric field between two sets of electrodes, charging particles and depositing them on the dust collection surface under the influence of Coulomb force, thus achieving particulate matter removal. However, in actual operation, factors such as dust deposition, humidity fluctuations, and the adhesion of oily aerosols can cause localized charge stacking and electric field distortion on the electrode surface, leading to phenomena such as increased leakage current, edge creepage, tip discharge, and spark discharge. Abnormal discharges not only create safety hazards and increase ozone byproducts but also cause carbonization or localized breakdown on the electrode surface, shortening filter life and increasing maintenance frequency. Especially in miniaturized devices with limited inter-electrode spacing, achieving higher electric field strength often requires increasing the applied voltage. However, traditional structures are more prone to discharge and arcing under conditions of concentrated edge field strength and uncontrolled charge discharge, limiting the upper limit of the usable operating voltage and making it difficult to balance efficiency and stability.

[0003] Meanwhile, existing improvement solutions often employ simple insulation covering and conventional safety distance design to suppress discharge. However, these solutions often suffer from problems such as a single charge discharge path, uncontrollable differences in discharge rates between the edge and inner regions, and the tendency for charge to accumulate in specific areas after long-term operation. This leads to a rapid decline in filtration efficiency over time, and even the occurrence of reverse electric fields and reduced capture capacity.

[0004] Furthermore, the change in boundary curvature of electrodes of different shapes can cause local electric field stress concentration. Without targeted compensation and current limiting mechanisms, it is difficult to stably suppress creepage channels that extend along the boundary by relying solely on overall coating or local insulation treatment. Consequently, the electrostatic filter still cannot maintain a high operating voltage and a low discharge risk under high humidity or high load dust conditions.

[0005] Therefore, there is an urgent need for an electrostatic filter structure that can create a controlled discharge difference between the electrode edge and the inner side and suppress the spread of abnormal discharge at the boundary, so as to increase the upper limit of the usable voltage, reduce the risk of discharge and extend the maintenance cycle. Summary of the Invention

[0006] To address the problems mentioned in the background section, the present invention provides the following technical solution: An electrostatic filter includes an outer frame, a filter assembly disposed within the outer frame and forming an air passage, and an electrode assembly; The electrode assembly includes staggered first electrode plates and second electrode plates, which are arranged facing each other to form multiple electric field gaps, and can be electrically connected to different polarity terminals of an external high-voltage power supply. Each electrode sheet includes an insulating substrate and a conductive electrode layer on its surface, the conductive electrode layer being formed on the surface of the insulating substrate by a patterning process; The conductive electrode layer of at least one first electrode sheet or at least one second electrode sheet retains an insulating edge around the edge of the insulating substrate, and the minimum distance between the boundary of the conductive electrode layer and the boundary of the insulating substrate is ≥0.1mm.

[0007] Furthermore, the conductive electrode layer includes a main conductive region and an edge release region disposed along the formation boundary; The surface resistivity of the edge slow-release region is greater than that of the main conductive region.

[0008] Furthermore, the electric field gap between adjacent first electrode plates and second electrode plates in the electrode assembly is 0.5-5 mm.

[0009] Furthermore, the conductive electrode layer is formed of a conductive material, a semi-conductive material, or a weakly conductive material, and the material of the conductive electrode layer is any one or any combination of graphite, graphene, a metal conductive layer, or a conductive plastic.

[0010] Furthermore, the insulating substrate is any one or any combination of PET, PP, PVC, ABS, PC, PS, PA or glass fiber, and the thickness of the insulating substrate is 0.1 mm to 1 mm. The conductive electrode layer is formed on the surface of the insulating substrate by at least one process, namely printing, injection molding or extrusion; the electrode sheet is elongated, square, arc or circular in shape.

[0011] Furthermore, the conductive electrode layer is formed only on one side of the insulating substrate, and when the first electrode sheet and the second electrode sheet are arranged facing each other, their conductive electrode layers are positioned facing each other.

[0012] In summary, the present invention has the following beneficial effects: By setting a fully covered weakly conductive coating layer on the outer surface of the conductive electrode layer and forming a first surface resistivity region and a second surface resistivity region at the edge, the charge discharge rate from the edge to the inside can be changed in a controlled gradient, thereby greatly reducing the problem of abnormal discharge and leakage current rise caused by edge charge stacking. By configuring a first surface resistivity region with higher surface resistivity near the formation boundary, the edge discharge current is constrained and the creepage probability induced by the sudden change in edge field strength is reduced, thereby solving the problem of difficulty in increasing the upper limit of operating voltage under the condition of limited inter-chip spacing. By setting a circumferential segmented structure of high-resistivity compensation section and discharge section in the first surface resistivity region, the arc channel is difficult to continuously expand along the boundary, thus solving the problem that the traditional structure will spread along the boundary and cause failure expansion once discharge occurs. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the stacked structure of the first and second electrode sheets of the present invention; Figure 3 This is a schematic diagram of the first and second electrode sheets of the present invention arranged in an alternating pattern to form a filter screen. Attached Figure Description

[0016] 1. First electrode sheet; 2. Second electrode sheet; 3. Insulating substrate; 4. Conductive electrode layer. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 The following is in conjunction with the appendix Figure 1-3 The present invention will be described in further detail below.

[0019] This invention provides a technical solution: an electrostatic filter, including an outer frame, a filter assembly disposed within the outer frame to form an air passage channel, and an electrode assembly. The electrode assembly includes a first electrode plate 1 and a second electrode plate 2 arranged in an alternating manner. The first electrode plate 1 and the second electrode plate 2 are arranged facing each other to form multiple electric field gaps, and each can be electrically connected to different polarity terminals of an external high-voltage power supply. Each electrode sheet includes an insulating substrate 3 and a conductive electrode layer 4 on its surface. The conductive electrode layer 4 is formed on the surface of the insulating substrate 3 by a patterning process. The conductive electrode layer 4 of at least one first electrode sheet 1 or at least one second electrode sheet 2 retains an insulating edge around the edge of the insulating substrate 3, and the minimum distance between the boundary of the conductive electrode layer 4 and the boundary of the insulating substrate 3 is ≥0.1mm. A cover layer may be provided on the outer surface of the conductive electrode layer 4 of at least one first electrode sheet 1 or at least one second electrode sheet 2. The cover layer is used to control the discharge of accumulated charge on the surface of the electrode sheet and suppress abnormal discharge. In this case, the conductive electrode layer 4 of the first electrode sheet 1 or the second electrode sheet 2 may not be provided with a covering layer, which can still ensure its normal use. The conductive electrode layer 4 is formed only on one side of the insulating substrate 3, and when the first electrode sheet 1 and the second electrode sheet 2 are arranged facing each other, the conductive electrode layers 4 of the two are arranged facing each other. The capping layer is a weakly conductive capping layer that fully covers the conductive electrode layer 4, and a gradient discharge structure with varying resistivity from the edge to the inside is formed in the edge region near the boundary. The gradient discharge structure includes a first surface resistivity region disposed along the formation boundary of the conductive electrode layer 4 and a second surface resistivity region located inside the first surface resistivity region. The first surface resistivity region is disposed corresponding to the insulating edge, and the second surface resistivity region is continuously transitioned or stepped transitioned to the first surface resistivity region. Furthermore, the surface resistivity of the first surface resistivity region is greater than that of the second surface resistivity region, causing the surface resistivity of the weakly conductive capping layer to decrease along the direction from the formation boundary toward the inward side. The surface resistivity of the weakly conductive capping layer is 1×10⁻⁶. 7 Ω to 1×10 12 Ω; In an optional embodiment, to further suppress creepage and abnormal discharge at the edge of the conductive electrode layer, an insulating material layer is provided outside the weakly conductive cover layer. The insulating material layer is continuously or intermittently distributed along the circumferential boundary of the conductive electrode layer, and the surface resistivity of the insulating material layer is not less than 1×10⁻⁶. 7 The boundary between the insulating material layer and the conductive electrode layer is maintained in a corresponding relationship, so that the edge region of the conductive electrode layer forms an insulating isolation barrier, thereby reducing the probability of discharge triggering under edge electric field stress concentration conditions and suppressing creepage channels that extend along the boundary. In another optional embodiment, to further suppress abnormal discharge at the edge of the conductive electrode layer, an insulating material layer is provided in the edge region of the conductive electrode layer. The insulating material layer is continuously or discontinuously distributed circumferentially along the formation boundary of the conductive electrode layer, and the surface resistivity of the insulating material layer is not less than 1×10⁻⁶. 7The insulating material layer and the weakly conductive covering layer can be set independently or partially overlapped in the edge area to provide additional insulation to the edge area of ​​the conductive electrode layer, thereby further suppressing creepage and arc discharge at the edge. The insulating substrate 3 is any one or any combination of PET, PP, PVC, ABS, PC, PS, PA or glass fiber, and the thickness of the insulating substrate 3 is 0.1mm to 1mm. The conductive electrode layer 4 is formed on the surface of the insulating substrate 3 by at least one of the processes of printing, injection molding or extrusion; the electrode sheet is elongated, square, arc or circular in shape.

[0020] In this embodiment: each electrode sheet includes an insulating substrate 3 and a conductive electrode layer 4 on its surface. The insulating substrate 3 can be made of PET sheet with a thickness of, for example, 0.1 mm to 1 mm, preferably about 0.25 mm. The conductive electrode layer 4 can be made of graphite conductive paste as the conductive material and is formed on the surface of the insulating substrate 3 by patterning forming processes such as screen printing. In one embodiment, it can be dried and cured at 60°C to 150°C for a curing time of, for example, 10 min to 30 min, to remove solvent and improve the adhesion stability between the conductive electrode layer 4 and the insulating substrate 3, thereby realizing the controllable forming of the electrode layer and providing a clear forming boundary diameter for the subsequent partitioning construction of the cover layer. To suppress abnormal discharges caused by edge tips, the conductive electrode layer 4 of at least one first electrode sheet 1 or at least one second electrode sheet 2 retains an insulating edge around the edge of the insulating substrate 3. In a specific process, the formation boundary of the conductive electrode layer 4 is shrunken inward relative to the boundary of the insulating substrate 3, so that the minimum distance between the formation boundary and the boundary of the insulating substrate 3 is ≥0.1mm, thereby reducing the trigger probability of edge discharge and creepage and increasing the upper limit of the withstand voltage. In this embodiment, a weakly conductive coating layer that fully covers the conductive electrode layer 4 can be provided on the outer surface of the conductive electrode layer 4. The weakly conductive coating layer can be a weakly conductive coating material composed of a polymer matrix and conductive fillers, and can achieve full coverage on the outer surface of the conductive electrode layer 4 by means of secondary printing, coating or lamination. In one embodiment, the thickness of the coating layer can be from 5 μm to 200 μm, preferably from 10 μm to 50 μm, so as to form a continuous coating layer without significantly increasing the electric field gap and to ensure that the overall surface resistivity of the coating layer is 1×10⁻⁶. 7 Up to 1×10 12 The weakly conductive window allows the electrode surface to still form a controllable charge discharge path and suppress continuous electric arcs even under long-term dust deposition conditions. To achieve controlled gradient discharge from the edge to the inside and suppress abnormal edge discharge, a first surface resistivity region and a second surface resistivity region are constructed adjacent to each other in the weakly conductive capping layer. The first surface resistivity region is located near the boundary of the conductive electrode layer 4 and corresponds to the insulating edge, while the second surface resistivity region is located inside the first surface resistivity region. The surface resistivity of the first surface resistivity region is greater than that of the second surface resistivity region, causing the surface resistivity of the capping layer to decrease along the direction from the boundary to the inside. The resistivity difference between the first and second surface resistivity regions can be achieved through a continuous transition or a stepped transition. A stepped transition can be achieved by printing a high-resistivity formula in the region near the boundary to form the first surface resistivity region and printing a lower-resistivity formula in the inner region to form the second surface resistivity region. A continuous transition can be achieved by dividing the above printing into multiple graded gradient printings, so that the areal density of the conductive filler in the capping layer gradually increases from the boundary to the inside and the surface resistivity of the transition zone gradually changes from the first surface resistivity region to the second surface resistivity region. In one embodiment, the overall surface resistivity of the weakly conductive capping layer can be 1×10⁻⁶. 7 Ω to 1×10 12 Ω range; During assembly and use, multiple first electrode plates 1 and multiple second electrode plates 2 are staggered and arranged facing each other in the outer frame, forming multiple electric field gaps in the air passage. The electrical connection terminals of the first electrode plates 1 are connected to one polarity of the external high-voltage power supply, and the electrical connection terminals of the second electrode plates 2 are connected to the other polarity of the external high-voltage power supply, so that a stable electric field is formed within the electric field gaps. By fully covering the weakly conductive coating layer and constructing a gradient discharge structure from high resistance to low resistance near the boundary, the charge discharge rate in the edge area is controlled and reduced, while the inner area has a stronger controlled discharge capability. This alleviates the problem of rapid decrease in filtration efficiency caused by the accumulation and stacking of dust-attached charges and reduces the risk of abnormal discharge at the edges.

[0021] Example 2 In this embodiment, each electrode sheet still includes an insulating substrate 3 and a conductive electrode layer 4 on its surface. The insulating substrate 3 can be made of insulating sheets such as PET, PP, or PC, with PET sheets being preferred. The thickness can be from 0.1 mm to 1 mm, for example, about 0.30 mm. The conductive electrode layer 4 can be made of conductive materials such as graphite, graphene, metal conductive paste, or conductive plastic paste, and can be formed on the surface of the insulating substrate 3 using patterning processes such as screen printing. In one embodiment, the material can be dried and cured at 60°C to 150°C for a curing time of, for example, 10 min to 40 min, to remove solvent and improve the adhesion stability between the conductive electrode layer 4 and the insulating substrate 3. The boundary of the conductive electrode layer 4 is recessed relative to the boundary of the insulating substrate 3. The recessed distance can be 0.1mm to 2mm, for example 0.25mm, so that the minimum distance between the boundary of the conductive electrode layer 4 and the boundary of the insulating substrate 3 is ≥0.1mm. At the same time, a continuous insulating edge is retained in the circumference of the insulating substrate 3 to reduce the probability of edge creepage and abnormal discharge. To ensure a stable and controlled discharge path at the edge of the conductive electrode layer, a surface resistivity distribution that gradually decreases from the outside to the inside is constructed near the formation boundary of the conductive electrode layer. Specifically, a first surface resistivity region is formed circumferentially along the formation boundary of the conductive electrode layer. This first surface resistivity region corresponds to and is arranged close to the formation boundary, providing stronger current limiting and insulation isolation at the edge. A second surface resistivity region is formed inside the first surface resistivity region to provide a lower resistance discharge path, allowing for controllable charge transfer inwards and completion of discharge. A transition zone is set between the resistivity regions. The transition zone is obtained by multiple gradual forming processes. That is, the capping layer is repeatedly formed at the same position and the amount of conductive filler transferred per unit area is gradually increased. This makes the content of conductive filler gradually increase from the forming boundary to the inward direction, so that the surface resistivity of the transition zone changes smoothly from the first surface resistivity region to the second surface resistivity region. The width of the first surface resistivity region, the second surface resistivity region and the transition zone can be determined according to the electrode sheet size and electric field gap design, so as to ensure the continuity of the edge discharge path and the stability of the zone resistivity distribution without significantly changing the electric field gap. During assembly and use, multiple first electrode plates 1 and multiple second electrode plates 2 are staggered and arranged facing each other in the outer frame, so that air passes through the channel to form multiple electric field gaps. The first electrode plates 1 and the second electrode plates 2 are connected to different polarity terminals of an external high-voltage power supply, and the applied voltage is increased step by step. In scenarios with dust deposition and humidity fluctuations, the high-resistivity first surface resistivity region at the edge suppresses the edge discharge current, and the low-resistivity second surface resistivity region on the inner side controls the discharge of charge accumulation. This reduces the probability of triggering abnormal discharge at the edge and slows down the filtration efficiency decay caused by charge stacking, thereby extending the filter cleaning and maintenance cycle and improving the stable operation time of the filter.

[0022] Example 3 like Figure 1-3 As shown, the weakly conductive capping layer is composed of a base material and a conductive filler. A transition zone is provided between the first surface resistivity region and the second surface resistivity region; the width of the transition zone is ≥0.1mm; In this embodiment, the electrode sheet is still composed of an insulating substrate 3 and conductive electrodes on its surface. The conductive electrodes are formed on the surface of the insulating substrate 3 by a printing process, and an insulating edge is retained around the edge of the insulating substrate 3. At the same time, the forming boundary of the conductive electrode is shrunken inward relative to the boundary of the insulating substrate 3, so that the minimum distance between the forming boundary and the boundary of the insulating substrate 3 is ≥0.1mm. When constructing a capping layer on the outer surface of the conductive electrode, a weakly conductive material that fully covers the conductive electrode is selected as the capping layer material, so that the surface resistivity of the cured capping layer is within ×10. 7 Ω to 1×10 12 The range of Ω is designed to provide a controllable charge discharge path and reduce the risk of abnormal discharge under conditions of dust deposition and humidity fluctuations. The weakly conductive coating is formed by combining a resin matrix and a conductive filler. The resin matrix can be acrylic resin, polyurethane resin or epoxy modified resin, and the conductive filler can be conductive carbon black, graphite powder or carbon nanotubes. The resin matrix and conductive filler are mixed and dispersed according to a preset mass fraction. The viscosity of the coating is controlled within the range suitable for screen printing. Then, multiple partition printings are performed on the outer surface of the conductive electrode and cured to form a continuous cover layer. To ensure the repeatability of resistivity in different zones, it is preferable to maintain consistent key printing conditions such as screen mesh count, squeegee pressure, and printing speed within the same production batch. The surface resistivity of different zones can be set by changing the mass fraction and transfer amount of conductive filler per unit area in the coating of each zone. The curing conditions of the cover layer can be determined based on the polymer matrix and solvent system to remove solvent and stabilize the micro-conductive network. In one embodiment, thermosetting can be performed at 60°C to 150°C for a holding time of, for example, 5 min to 60 min, preferably, for example, 80°C to 120°C for 10 min to 30 min, to reduce batch fluctuations. When constructing adjacent high-resistivity and low-resistivity regions in the edge region of the weakly conductive coating layer, a first surface resistivity region close to the formation boundary is set along the periphery of the formation boundary of the conductive electrode, and a second surface resistivity region is set inside it. To suppress abnormal discharge at the edge of the conductive electrode layer 4 and improve the stability of controlled discharge, a covering layer may be provided on the surface of the conductive electrode layer 4. The covering layer may be an insulating material layer that partially covers the conductive electrode layer 4, and its surface resistivity is not less than 1×10⁻⁶. 7 Ω can also be a weakly conductive material layer that fully covers the conductive electrode layer 4, with a surface resistivity of 1×10⁻⁶. 7 Ω to 1×10 12 Ω; When using a weakly conductive material layer, the edge region near the boundary of the conductive electrode layer 4 can have a higher surface resistivity than the inner region, so that the charge can be discharged more smoothly from the edge to the inside and the probability of edge discharge is reduced. The cover layer can be formed by printing process, or it can be achieved by combining patterned forming methods such as injection molding or extrusion. Different surface resistivity distributions can be obtained by adjusting the content of conductive filler in the cover layer material and the amount of forming per unit area, thereby reducing batch fluctuations and improving repeatability. The formation of high-resistivity compensation and venting sections can be achieved through a combination of zoned formulation and zoned printing. Specifically, the same cover layer matrix system can be used. In the screen printing area corresponding to the high-resistivity compensation section, the proportion of resin matrix is ​​increased and the mass fraction of conductive filler is reduced, making the conductive interconnect network sparser after curing to obtain higher surface resistivity. At the same time, in the screen printing area corresponding to the venting section, the mass fraction of conductive filler or the transfer amount per unit area is increased, making the conductive interconnect network more continuous after curing to obtain lower surface resistivity. In terms of process consistency control, the areal density of conductive filler can be calculated by converting the mass difference of the cover layer before and after curing with the effective printing area. The surface resistivity can be sampled and measured at multiple points around the perimeter of the boundary after the cover layer is cured, including the center point of the high-resistivity compensation section, the center point of the discharge section, and the transition zone, and the average value is taken to verify the stability of the segmented resistivity and gradient transition. Through the synergistic effect of the transition zone formed by the gradient printing and the high-resistivity compensation section and discharge section formed by the circumferential segmentation, the charge discharge in the edge region can be spatially gradient-change from the edge to the inside, and in the circumferential direction, it can be distributed in a discontinuous current limiting and current releasing alternately. Thus, while keeping the overall diameter of the fully covered weakly conductive material unchanged, the suppression effect on abnormal discharge and creepage propagation at the edge is enhanced.

[0023] Example 4 like Figure 1-3 As shown, the conductive electrode layer 4 includes a main conductive region and an edge slow-release region disposed along the formation boundary; The surface resistivity of the edge release region is greater than that of the main conductive region. Several strip-shaped high-resistivity structures are formed at the edge region of the conductive electrode layer. These strip-shaped high-resistivity structures extend along the boundary of the conductive electrode layer and are spaced apart from each other within the edge region. Compared with the inner region of the conductive electrode layer, the strip-shaped high-resistivity structures have a higher surface resistivity, preventing the edge region of the conductive electrode layer from exhibiting a continuous and uniform low-resistivity surface. Instead, they form a current-limiting surface composed of alternating high-resistivity strips and spacers, thereby reducing the probability of creepage and abnormal discharge at the edge. The strip-shaped high-resistivity structures can be achieved by first forming high-resistivity material strips on the surface of the insulating substrate and then forming the conductive electrode layer, or by superimposing and printing high-resistivity material strips on the surface of the conductive electrode layer. The width of each strip can be selected from 0.05 mm to 0.5 mm, and the spacing between adjacent strips can be selected from 0.05 mm to 1 mm. These values ​​are examples and are used to illustrate that the strips can form a dense edge current-limiting distribution, but do not constitute a limitation. The first surface resistivity region of the weakly conductive capping layer covers at least the edge release region and the edge region of the adjacent conductive electrode layer 4, so that the edge release region and the first surface resistivity region are spatially superimposed to form a synergistic region of potential release and gradient discharge, thereby reducing the trigger probability of abnormal edge discharge and suppressing creepage channels that extend along the boundary direction. Several damping strips are set in the edge region. The damping strips extend along the boundary of the conductive electrode layer and are arranged at intervals. At the corners, sharp turns, or locations where the boundary shape changes more significantly, the damping strips are set more densely, that is, the spacing between adjacent damping strips is smaller or the number of damping strips per unit length is greater. The purpose is to make these edge locations, which are more prone to partial discharge, have a stronger current limiting effect, thereby reducing the probability of triggering abnormal edge discharge. In this embodiment, the electrostatic filter still includes an outer frame, a filter assembly disposed within the outer frame to form an air passage channel, and an electrode assembly. The electrode assembly is composed of electrode plates A and B arranged alternately and facing each other. Electrode plates A and B can be electrically connected to different polarity terminals of an external high-voltage power supply to form multiple electric field gaps between the electrode plates. Electrode plates A and B are both composed of an insulating substrate 3 and a conductive electrode layer 4 on its surface. The conductive electrode layer 4 is formed on the surface of the insulating substrate 3 by a printing process, and at least one electrode plate retains an insulating edge around the edge of the insulating substrate 3 and the forming boundary of the conductive electrode layer 4 is recessed relative to the boundary of the insulating substrate 3, thereby ensuring that the minimum distance between the forming boundary and the boundary of the insulating substrate 3 is ≥0.1mm. The printing of conductive electrode layer 4 employs a two-stage process with two sets of pastes to control the resistance difference between the main conductive area and the edge slow-release area. The first set of paste is used to form the main conductive area, selecting a conductive, semi-conductive, or weakly conductive material and obtaining a continuous main conductive pattern through screen printing. The second set of paste is used to form the edge slow-release area distributed along the formation boundary. The second set of paste reduces the mass fraction of conductive filler or the transfer amount per unit area compared to the first set of paste, making the surface resistivity of the edge slow-release area greater than that of the main conductive area. In this embodiment, the surface resistivity of the main conductive area is approximately 5 × 10⁻⁶. 5 Ω and the surface resistivity of the edge slow-release region is approximately 5 × 10⁻⁶. 6 Ω serves as an example, achieving an equivalent current-limiting basis for edge regions through partitioned formulation and partitioned printing, thereby reducing transient accumulation of boundary charges and suppressing the triggering of abnormal edge discharges; The edge relief zone is further implemented in the form of damping strips. The damping strips extend along the formation boundary direction of the conductive electrode layer 4 and are printed. The strip width is controlled within the range of 0.05mm to 0.5mm, and the spacing between adjacent damping strips is controlled within the range of 0.05mm to 1mm. To form a current-limiting intensity distribution that matches the boundary electric field stress distribution, the damping strips are segmented along the formation boundary direction and correspond to the segmented resistivity design of the edge region of the weakly conductive cover layer. The locations of abrupt changes in boundary curvature or electric field stress concentrations correspond to the locations of high-resistivity compensation sections, and the remaining boundary locations correspond to the locations of venting sections. The spacing between adjacent damping strips is controlled within the range of 0.05mm to 0.2mm, and the linear density of the damping strips is increased. At the corresponding position of the discharge section, the spacing between adjacent damping strips is controlled within the range of 0.2mm to 1mm, and the linear density of the damping strips is reduced. Furthermore, the number of damping strips per unit length at the corresponding position of the high-resistance compensation section is greater than twice the number of damping strips per unit length at the corresponding position of the discharge section. In this embodiment, the spacing between the corresponding positions of the high-resistance compensation section and the corresponding positions of the discharge section is 0.10mm and 0.60mm, respectively, as examples. This allows the location where the boundary electric field stress is more concentrated to have stronger edge current limiting capability and further suppress the creepage channel that extends along the boundary. After the conductive electrode layer 4 and the damping strip have cured, a weakly conductive coating layer is constructed on the outer surface of the conductive electrode layer 4 to fully cover it. The weakly conductive coating layer is made of a weakly conductive material system with a surface resistivity of 1×10⁻⁶. 7 Ω to 1×10 12 Within the Ω range, the capping layer forms a gradient discharge structure from the 4th periphery of the conductive electrode layer towards the edge and forms a first surface resistivity region near the boundary. A second surface resistivity region is formed inside the first surface resistivity region. The first surface resistivity region at least covers the edge slow-release region, so that the edge slow-release region and the first surface resistivity region are spatially superimposed and form an equivalent series current-limiting discharge path, thereby enabling the charge accumulation at the electrode sheet boundary to be discharged through a controlled path and reducing the probability of abnormal discharge. To verify the effectiveness of the above structure under the disclosed conditions, the applicable voltage range of the relative humidity 50% and the inter-panel spacing 1.5mm was compared. The typical comparison given in the disclosure is that the applicable voltage of the relative arrangement is about 3kV to 4kV, while the inter-panel arrangement can be increased to 5kV to 6kV, with lower leakage current and less discharge arcing. The test prototype was an air purifier with an air volume of approximately 300 m³ / h, and the test was conducted in accordance with the test requirements for Clean Air Delivery Rate (CADR) and Cumulative Clean Capacity (CADR) in GB18801-2022. Some CADR comparison data from the handover record are shown below: Table 1. Comparison of Clean Air Delivery Rate (CADR) under different smoking volumes 1 0 267 270 2 3750 207 265 3 7500 124 265 4 10000 / 262 5 15000 266 6 33000 252 7 51000 253 8 64500 253 9 78000 264 10 94500 272 11 103500 240 12 112500 259 13 123000 255 14 136500 250 15 148500 243 16 162000 240 17 175500 250 18 183000 264 19 195000 261 20 201000 238 21 216000 240 22 225000 255 Among them, the ordinary filter described in Table 1 corresponds to the wrapped electrode structure or conventional electrode structure filter in the disclosure document; the optimized filter described in Table 1 corresponds to the single-sided printed electrode facing-to-facing filter in the disclosure document and adopts the controlled discharge structure of the present invention.

[0024] Example 5 like Figure 1-3 As shown, the electric field gap between adjacent first electrode plate 1 and second electrode plate 2 in the electrode assembly is 0.5-5mm; With an electric field gap of 1.5 mm and a relative humidity of 50%, the electrode assembly can be used with an external high-voltage power supply to apply a peak working voltage of 5 kV to 6 kV without continuous arc discharge. In this embodiment, the electrode assembly is composed of a first electrode plate 1 and a second electrode plate 2 arranged alternately and facing each other. The first electrode plate 1 and the second electrode plate 2 are electrically connected to different polarity terminals of an external high-voltage power supply through electrical connection terminals to form multiple electric field gaps in the air passage. In order to balance the electric field strength and the risk of discharge in the miniaturized structure, the electric field gap between adjacent first electrode plates 1 and second electrode plates 2 is controlled to be 0.5mm to 5mm, and 1.5mm is used as a typical gap value for working condition verification. During assembly, the spacing between the plates is limited by insulating positioning ribs or insulating spacers, and a limiting structure is set in the outer frame to reduce gap drift caused by vibration, so that the electric field gap is maintained within the set range during operation. Regarding environmental conditions, the relative humidity of the experimental chamber was controlled at 50%, and the temperature was maintained between 20°C and 30°C. Under these conditions, a step-by-step voltage increase test was performed on the external high-voltage power supply. The output of the external high-voltage power supply could be either DC high voltage or pulsed DC high voltage, with DC high voltage output being preferred for stable observation of the discharge state. The voltage peak was gradually increased from 3kV to 6kV, and each voltage plateau was maintained for 30s to 300s. The discharge state of the electrode assembly and audible sounds were recorded, and the presence of continuous arc discharge was determined by combining the power supply output current waveform. Continuous arc discharge can be defined as an arc duration greater than 0.5s or a state in which the number of consecutive arcs per unit time exceeds a preset threshold. In this embodiment, an arc duration greater than 0.5s is used as the judgment condition, and the arc emission is assisted by setting a darkroom observation window or a photoelectric detector. Under the conditions of a 1.5mm interlayer spacing and 50% relative humidity, the peak operating voltage of the external high-voltage power supply was controlled within the range of 5kV to 6kV for verification. When the peak voltage was within this range and remained stable, no continuous arc discharge was observed within the electrode boundary and electric field gap. Furthermore, no obvious carbonization discharge trace was formed on the electrode surface after multiple voltage boosting and deboosting cycles. By limiting the electric field gap to the range of 1mm to 2mm and verifying the applicable peak voltage range under typical operating conditions with 50% humidity, the electrode assembly can achieve a higher electric field strength while reducing the risk of discharge arcing, thereby improving the stable operation capability and the upper limit of the usable operating voltage of the electrostatic filter in practical applications.

[0025] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. An electrostatic filter, comprising an outer frame, a filter assembly disposed within the outer frame and forming an air passage, and an electrode assembly, characterized in that: The electrode assembly includes a first electrode plate (1) and a second electrode plate (2) arranged in an alternating manner. The first electrode plate (1) and the second electrode plate (2) are arranged facing each other to form multiple electric field gaps, and can be electrically connected to different polarity terminals of an external high-voltage power supply. Each electrode sheet includes an insulating substrate (3) and a conductive electrode layer (4) on its surface, wherein the conductive electrode layer (4) is formed on the surface of the insulating substrate (3) by a patterning process. The conductive electrode layers (4) of at least one first electrode sheet (1) and at least one second electrode sheet (2) retain an insulating edge around the edge of the insulating substrate (3), and the minimum distance between the boundary of the conductive electrode layer (4) and the boundary of the insulating substrate (3) is ≥0.1mm; The conductive electrode layer (4) includes a main conductive region and an edge slow-release region disposed along the formation boundary; The surface resistivity of the edge release region is greater than that of the main conductive region. The edge release zone includes damping strips that extend along the direction of the forming boundary and are spaced apart from each other. The damping strips are segmented along the direction of the forming boundary, and the curvature change position or electric field stress concentration position of the forming boundary corresponds to the high resistance compensation section position, and the other boundary positions correspond to the discharge section positions. At the corresponding position of the high-resistance compensation section, the spacing between adjacent damping strips is controlled within the range of 0.05mm to 0.2mm and the linear density of the damping strips is increased. At the corresponding position of the discharge section, the spacing between adjacent damping strips is controlled within the range of 0.2mm to 1mm and the linear density of the damping strips is reduced. Furthermore, the number of damping strips per unit length at the corresponding position of the high-resistance compensation section is ≥ twice the number of damping strips per unit length at the corresponding position of the discharge section. The outer surface of the conductive electrode layer (4) is provided with a weakly conductive covering layer that fully covers the conductive electrode layer (4). The weakly conductive covering layer includes a first surface resistivity region disposed along the forming boundary and a second surface resistivity region located inside the first surface resistivity region. The first surface resistivity region is disposed corresponding to the insulating edge, and the second surface resistivity region is continuously transitioned or stepped transitioned to the first surface resistivity region. The surface resistivity of the first surface resistivity region is greater than that of the second surface resistivity region, causing the surface resistivity of the weakly conductive capping layer to decrease along the direction from the formation boundary toward the inward side. The first surface resistivity region at least covers the edge release region, such that the edge release region and the first surface resistivity region are spatially superimposed and form an equivalent series current-limiting discharge path.

2. An electrostatic filter according to claim 1, characterized in that, The electric field gap between adjacent first electrode sheet (1) and second electrode sheet (2) in the electrode assembly is 0.5-5mm.

3. An electrostatic filter according to claim 2, characterized in that, The conductive electrode layer (4) is formed of a conductive material, a semi-conductive material, or a weakly conductive material, and the material of the conductive electrode layer (4) is any one or any combination of graphite, graphene, a metal conductive layer, or a conductive plastic.

4. An electrostatic filter according to claim 3, characterized in that, The insulating substrate (3) is any one or any combination of PET, PP, PVC, ABS, PC, PS, PA or glass fiber, and the thickness of the insulating substrate (3) is 0.1 mm to 1 mm. The conductive electrode layer (4) is formed on the surface of the insulating substrate (3) by at least one of the processes of printing, injection molding or extrusion; the electrode sheet is elongated, square, arc or circular in shape.

5. An electrostatic filter according to claim 4, characterized in that, The conductive electrode layer (4) is formed only on one side of the insulating substrate (3), and when the first electrode sheet (1) and the second electrode sheet (2) are arranged facing each other, their conductive electrode layers (4) are arranged facing each other.

Images