Gas discharge tube having enhanced ratio of leakage path length to gap dimension

Abstract

To provide a gas discharge tube (GDT) which is a device having a volume of gas confined between two electrodes and provides reliable and effective protection for various applications during electrical disturbances.SOLUTION: A gas discharge tube includes first and second electrodes each including an edge and an inward facing surface, such that the inward facing surfaces of the first and second electrodes face each other. The GDT further includes a sealing portion implemented to join and seal edge portions of the inward facing surfaces of the first and second electrodes to define a sealed chamber between the inward facing surfaces of the first and second electrodes. The GDT can further include an electrically insulating portion implemented to form a surface in the sealed chamber and to cover a portion of the inward facing surface of each of at least one of the first and second electrodes such that a leakage path within the sealed chamber includes the surface of the electrically insulating portion.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority to U.S. Provisional Application No. 62 / 863,777, filed on June 19, 2019, under the title "GAS DISCHARGE TUBE HAVING ENHANCED RATIO OF LEAKAGE PATH LENGTH TO GAP DIMENSION", the disclosure of which is hereby expressly incorporated by reference in its entirety.

[0002] This disclosure relates to gas discharge tubes (GDTs) and related methods and devices.

Background Art

[0003] A gas discharge tube (GDT) is a device having a gas volume sealed between two electrodes. When there is a sufficient potential difference between the two electrodes, the gas can be ionized to become a conductive medium, thereby generating a current in the form of an arc.

[0004] Based on such operating principles, GDTs can be configured to provide highly reliable and effective protection for various applications during electrical disturbances. In some applications, GDTs may be preferred over semiconductor discharge devices due to characteristics such as low capacitance and low insertion / return loss. Therefore, GDTs are frequently used in telecommunication and other applications where protection against electrical disturbances such as overvoltage is desired.

Summary of the Invention

Means for Solving the Problems

[0005] In some embodiments, the present disclosure relates to a gas discharge tube (GDT) including first and second electrodes each including an edge and an inward-facing surface, wherein the inward-facing surfaces of the first and second electrodes face each other. The GDT further includes a seal implemented to join and seal edge portions of the inward-facing surfaces of the first and second electrodes to define a sealed chamber between the inward-facing surfaces of the first and second electrodes. The GDT further includes an electrical insulator implemented to form a surface within the sealed chamber and cover a portion of each of the inward-facing surfaces of at least one of the first and second electrodes, wherein a leak path within the sealed chamber includes the surface of the electrical insulator.

[0006] In some embodiments, the electrical insulator may be implemented on each of the first and second electrodes.

[0007] In some embodiments, the GDT may further include a spacer implemented between the first and second electrodes. The spacer may define an opening having a first surface and a second surface and an inner wall extending from the first surface to the second surface, and the sealed chamber may be further defined by the inner wall. In some embodiments, the spacer may be formed of an electrically insulating material such as ceramic. In some embodiments, the leak path may have a length greater than the thickness dimension of the spacer. In some embodiments, the leak path may have a length including the sum of the path associated with each electrical insulator and the thickness dimension of the spacer.

[0008] In some embodiments, the seal may include a sealing layer implemented between each of the first and second surfaces of the spacer and the corresponding electrode.

[0009] In some embodiments, the sealing layer may be formed of a conductive material. In some embodiments, each electrical insulator may extend laterally inward from the inner wall of the opening of the spacer, and each sealing layer may be separated from the electrical insulator by the electrically insulating material of the spacer.

[0010] In some embodiments, the encapsulation layer may be formed of an electrically insulating material. In some embodiments, each of the electrical insulating portions may also be formed of the electrically insulating material of the encapsulation layer. In some embodiments, each of the electrical insulating portions and the encapsulation layer may form a continuous structure. In some embodiments, the electrically insulating material of the encapsulation layer may include glass.

[0011] In some embodiments, the spacer may have dimensions such that it extends laterally from the inner wall to the outer wall that is substantially coplanar with the outer edges of the first and second electrodes.

[0012] In some embodiments, the spacer may have dimensions such that it extends laterally from the inner wall to the outer wall that extends laterally beyond the outer edges of the first and second electrodes. The spacer may include a notch structure at the corner of the outer wall of at least one of the first and second sides, and the notch structure may be due to the separation of the spacer from other spacers. The external leakage path length between the first and second electrodes may be increased by the spacer that extends laterally beyond the outer edges of the first and second electrodes.

[0013] In some embodiments, the encapsulation portion may be formed of an electrically insulating material and configured to directly bond and encapsulate the first and second electrodes without a spacer. Each of the electrical insulating portions may extend laterally inward from the encapsulation portion. In some embodiments, each of the electrical insulating portions may also be formed of the electrically insulating material of the encapsulation portion. In some embodiments, the electrical insulating portion and the encapsulation portion may form a continuous structure. In some embodiments, the electrically insulating material of the encapsulation portion may include glass.

[0014] In some embodiments, each of the first and second electrodes may be formed of a metal layer. Each electrical insulation portion may have dimensions such that the discharge portion is exposed on the inward-facing surface of each electrode. In some embodiments, the discharge portion of the electrode may include one or more layers mounted on the inward-facing surface of the metal layer. Such one or more layers may include a silver ink layer. Such one or more layers may further include a silver texture layer on the silver ink layer. Such one or more layers may further include a radiation coating layer on the silver texture layer.

[0015] In some embodiments, the discharge portion of the electrode may include a texture structure formed on the inward-facing surface of the metal layer. The texture structure may include a stamped metal structure formed on the metal layer. In some embodiments, the discharge portion of the electrode may further include a radiation coating layer on the texture structure.

[0016] In some embodiments, the discharge portion and the portion of each inward-facing surface covered by the electrical insulation portion may be substantially flat.

[0017] In some embodiments, the discharge portion and the portion of each inward-facing surface covered by the electrical insulation portion may form a concave surface. In some embodiments, the concave surface may include a substantially flat inner portion and an angled outer portion, with at least a portion of the angled outer portion being covered by each electrical insulation portion. In some embodiments, substantially all of the angled outer portion may be covered by each electrical insulation portion.

[0018] In some embodiments, the present disclosure relates to a method of manufacturing a gas discharge tube (GDT). The method includes forming or providing first and second electrodes, each including an edge and an inward-facing surface. The method further includes covering a portion of the inward-facing surface of at least one of the first and second electrodes with an electrically insulating material. The method is joining and sealing a portion of the edges of the inward-facing surfaces of the first and second electrodes to define a sealed chamber between the inward-facing surfaces of the first and second electrodes, such that a leak path within the sealed chamber includes a surface of the electrically insulating material.

[0019] In some embodiments, joining and sealing a portion of the edges of the inward-facing surfaces of the first and second electrodes may include providing an electrically insulating spacer between the first and second electrodes, the spacer defining an opening having a first surface and a second surface and an inner wall extending from the first surface to the second surface, the sealed chamber being further defined by the inner wall.

[0020] In some embodiments, joining and sealing a portion of the edges of the inward-facing surfaces of the first and second electrodes may further include forming a sealing layer mounted between each of the first and second surfaces of the spacer and the corresponding electrode.

[0021] In some embodiments, joining and sealing a portion of the edges of the inward-facing surfaces of the first and second electrodes may include forming an electrically insulating portion formed of an electrically insulating material to directly join and seal the first and second electrodes without a spacer.

[0022] In some embodiments, the present disclosure relates to a method of manufacturing a plurality of gas discharge tubes (GDTs). The method includes providing or forming an electrically insulating plate that defines an array of spacer units, where each spacer unit has a first and a second surface and defines an opening having an inner wall extending from the first surface to the second surface. The method further includes forming or providing first and second electrodes, each including an edge and an inward-facing surface. The method further includes covering a portion of the inward-facing surface of at least one of the first and second electrodes with an electrically insulating material. The method further includes sealing the opening of each spacer unit with the first and second electrodes, where an edge portion of the inward-facing surfaces of the first and second electrodes defines a sealed chamber between the inward-facing surfaces of the first and second electrodes and the leak path within the sealed chamber includes the surface of the electrically insulating material.

[0023] In some embodiments, the method may further include separating the array of spacer units into a plurality of discrete units.

[0024] In some embodiments, the method may further include providing or forming a metal sheet having an array of electrode units and separating the array of electrode units to provide the first and second electrodes.

[0025] In some embodiments, the present disclosure relates to a circuit protection device including a gas discharge tube (GDT) having first and second electrodes each including an edge and an inward-facing surface, the inward-facing surfaces of the first and second electrodes being oriented to face each other. The GDT further includes a seal implemented to join and seal portions of the edges of the inward-facing surfaces of the first and second electrodes to define a sealed chamber between the inward-facing surfaces of the first and second electrodes. The GDT further includes an electrical insulator implemented to form a surface within the sealed chamber and cover a portion of each of the inward-facing surfaces of at least one of the first and second electrodes, the leak path within the sealed chamber including the surface of the electrical insulator. The circuit protection device further includes a first clamping device electrically connected to the first electrode of the GDT.

[0026] In some embodiments, the first clamping device may be directly connected to the first electrode. In some embodiments, the first clamping device may be a metal oxide varistor (MOV) having the first and second electrodes and a metal oxide layer implemented between the first and second electrodes. In some embodiments, one of the first and second electrodes of the MOV may be configured as a terminal of the circuit protection device, and the other electrode of the MOV may be another electrode electrically connected to the first electrode of the GDT. In some embodiments, one of the first and second electrodes of the MOV may be configured as a terminal of the circuit protection device, and the first electrode of the GDT may be configured as the other electrode of the MOV.

[0027] In some embodiments, the circuit protection device may further include a second clamping device electrically connected to the second electrode of the GDT. In some embodiments, the second clamping device may be a metal oxide varistor (MOV) having the first and second electrodes and a metal oxide layer implemented between the first and second electrodes.

[0028] For purposes of summarizing the disclosure, certain aspects, advantages, and novel features of the invention are described herein. It is to be understood that such advantages need not all be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or practiced so as to achieve one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0030] If there are headings in this specification, they are for convenience only and do not necessarily affect the scope or intent of the invention described in the claims.

[0031] A gas discharge tube (GDT) is a device having a sealed gas chamber with opposing electrodes. When such a GDT is exposed to an electrical state such as an overvoltage state, an arc discharge occurs through the electrodes and the sealed gas, thereby discharging the overvoltage state. Therefore, in the design of the GDT, according to the purpose of use of the GDT, for example, the type of gas, the gap dimension between the electrodes, the dimension of the entire device, etc. can be included.

[0032] In a typical GDT, a leakage current may exist between the electrodes. Such a leakage current usually follows a leakage path from one electrode to the other along various surfaces of the sealed chamber. In many applications of GDTs, it is desirable to reduce such a leakage current. To achieve such a reduction of the leakage current, the corresponding leakage path can be increased. In some embodiments, it is desirable to have a leakage path that is long relative to the gap dimension of the corresponding electrodes.

[0033] Figures 1A and 1B show examples of how the leakage path can be increased to reduce the leakage current. For example, Figure 1A shows a GDT 10 having a leakage path 19 that includes the thickness dimension of a relatively thick spacer 14. Such a spacer is shown as joining the first and second electrodes 12a, 12b and respective seals 16a, 16b so as to form a sealed chamber 18. In such a configuration, the electrodes 12a, 12b (having optional emissive coatings 15a, 15b) can project towards each other so as to form a desired gap dimension d gap . It can be seen that in such a configuration, the relatively thick spacer 14 makes the GDT 10 relatively thick.

[0034] In another example, Figure 1B shows a GDT 20 that is thinner than the example of Figure 1A. In the example of Figure 1B, the spacer 24 is shown as including inward protrusions such that the leakage path length is increased for a spacer of reduced thickness. Such a spacer is shown as joining the first and second electrodes 22a, 22b and respective seals 26a, 26b so as to form a sealed chamber 28. In the example of Figure 1B, the electrodes 22a, 22b (having optional emissive coatings 25a, 25b) do not need to project towards each other (as compared to the example of Figure 1A) to form the desired gap dimension d gap . It should be noted that in the example of Figure 1B, the spacer 24 having inward protrusions generally has a more complex shape than, for example, the spacer of Figure 1A.

[0035] In some embodiments, the GDT can have an increased leakage path length while using a relatively thin and simple spacer shape. As described herein, such a GDT can also desirably include relatively simple electrodes.

[0036] For example, FIG. 2 shows a GDT 100 having upper and lower electrodes 102a, 102b that can be formed in a relatively simple structure such as a flat conductive plate. As described herein, the discharge portions of such electrodes can be implemented with one or more layers 105a, 105b formed on respective flat conductive plates.

[0037] In the example of FIG. 2, each electrode (102a or 102b) includes a discharge portion that protrudes slightly toward the opposing discharge portion of the other electrode (102b or 102a) to form a desired gap dimension d gap When a flat spacer having an opening is implemented such that the inner wall of the opening is at or inside the edge of the discharge portion, the resulting leakage path length is essentially the thickness of the flat spacer.

[0038] However, as shown in the example of FIG. 2, when the inner wall of the opening of the flat spacer 104 is located outside the edge of the discharge portion, the resulting leakage path 110 includes, in addition to the thickness of the flat spacer 104, a lateral offset (formed by a portion of respective insulating seals 106a, 106b) from the edge of each discharge portion to the inner wall of the opening of the flat spacer 104. In some embodiments, as described herein, the insulating seals (106a, 106b) associated with each electrode (102a, 102b) can include a surface of an insulating material (such as glass) to form the above-described lateral offset for the leakage path 110.

[0039] In the example of FIG. 2, the inner wall of the opening of the spacer 104, a part of the insulating seals 106a, 106b, and the discharge parts of the electrodes 102a, 102b are shown to form the sealed chamber 108. Additional examples related to the GDT 100 of FIG. 2 are described in more detail herein.

[0040] FIGS. 3 and 4 show more detailed examples of the increased leak path length described above with reference to FIG. 2. In each of FIGS. 3 and 4, the GDT 100 is shown to include first and second electrodes 102a, 102b arranged relative to each other such that their respective discharge parts are separated by a gap dimension d gap For the sake of explanation, it will be understood that the discharge part of the electrode refers to the location where the discharge starts or ends at the discharge part.

[0041] In each of FIGS. 3 and 4, each of the first and second electrodes 102a, 102b is depicted as including a flat portion and a protruding discharge part. In some embodiments, as described herein, such a discharge part can be implemented with one or more layers formed on the flat portion.

[0042] Referring to FIGS. 3 and 4, an electrical insulating seal (106a or 106b) (also referred to herein as an insulating seal) can be implemented to occupy some or all of the space surrounding the lateral outer portion of the corresponding discharge part. Thus, in some embodiments, the protruding discharge part and the insulating seal (106a or 106b) can have substantially the same thickness. In such a configuration example, the electrode (102a or 102b) and the insulating seal (106a or 106b) can form a substantially flat structure. Although several examples are described herein in the context of such a substantially flat structure, it will be understood that the insulating seal can have a thickness greater than or less than the thickness of the protruding discharge part.

[0043] It will also be understood that the discharge part of the electrode may or may not protrude from the conductive surface of the electrode. For example, in some embodiments, the flat portion of the flat conductive surface of the electrode can be surrounded by an electrical insulation seal as described herein, and the exposed portion of such a flat conductive surface can be the discharge part of the electrode. When one or more layers such as a silver texture layer and a radiation coating layer are formed on such an exposed portion, the resulting layer having a thickness smaller than, equal to, or larger than the surrounding electrical insulation seal can be regarded as the discharge part of the electrode.

[0044] Referring to FIGS. 3 and 4, in some embodiments, the GDT 100 can further include a generally flat spacer 104 having an opening that defines the chamber 108. In each example of FIGS. 3 and 4, it is shown that the inner wall of the spacer 104 is recessed outward from the outer edge of the discharge part of each electrode 102a, 102b. Thus, the resulting recess is shown to have a lateral dimension d recess As such, when the dimensions of the discharge parts of the electrodes 102a, 102b are similar, the leakage path 110 between the outer edge of one discharge part and the outer edge of the other discharge part can be approximately d recess +d gap + the length of drecess.

[0045] It will be understood that in some embodiments, the discharge parts of the electrodes 102a, 102b may or may not have the same dimensions.

[0046] FIG. 3 shows that in some embodiments, the spacer 104 can have an outer wall that is substantially coplanar with the outer walls of the electrodes 102a, 102b.

[0047] FIG. 4 shows that in some embodiments, the spacer 104 can have an outer wall that is laterally outside the outer walls of the electrodes 102a, 102b. In such a configuration of FIG. 4, the spacer protruding laterally (beyond the outer walls of the electrodes 102a, 102b) can form a wing-like structure when the GDT 100 is viewed from the side. In some embodiments, such a wing-like structure can facilitate some desirable manufacturing processes. Examples of such manufacturing processes are described in more detail herein. It should also be noted that the above-described outer wing-like structure can also form a long leakage path outside the GDT 100.

[0048] FIG. 5 shows a more specific example of the GDT of FIG. 4. In the example of FIG. 5, the GDT 100 is shown to include first and second electrodes 102a, 102b mounted on the first and second faces (e.g., the upper and lower faces when oriented as in FIG. 5) of the electrical insulating spacer 104. In some embodiments, the first electrode 102a can include a first metal sheet 120a (e.g., a stamped flat metal sheet), and a number of layers can be formed on such a metal sheet to provide a discharge portion. For example, a silver ink layer 122a can be formed to substantially cover one face of the metal sheet 120a. A silver texture layer 124a and a radiation coating layer 126a are shown to be formed in the central portion of the silver ink layer 122a so as to form a discharge portion in the central portion of the first electrode 102a. It will be understood that such a discharge portion can be formed to be symmetric with respect to a center line extending between the first and second electrodes 102a, 102b, or can be formed to be asymmetric away from the central portion.

[0049] Similarly, referring to FIG. 5, the second electrode 102b can include a second metal sheet 120b (e.g., a stamped flat metal sheet), and a number of layers can be formed on such a metal sheet to provide a discharge portion. For example, a silver ink layer 122b can be formed to substantially cover one surface of the metal sheet 120b. A silver texture layer 124b and a radiation coating layer 126b are shown to be formed in the central portion of the silver ink layer 122b so as to form a discharge portion at the central portion of the second electrode 102b. It will be appreciated that such a discharge portion can be formed to be symmetric with respect to a center line extending between the first and second electrodes 102a, 102b, or can be formed to be asymmetric away from the central portion. Also, it will be appreciated that the individual layers of the second electrode 102b may or may not be the same as the individual layers of the first electrode 102a.

[0050] In some embodiments, an electrode for a GDT having one or more features (such as the example of FIG. 5) as described herein can be implemented as a metal electrode (e.g., copper or 42 alloy metal) without using silver ink or texture. In such embodiments, a texture structure can be stamped onto the metal electrode. Such stamping of the texture structure can be done during the formation of the electrode itself (in an example where the electrode is a stamped metal electrode), or in another step before or after the electrode formation step. In some embodiments, a radiation coating may or may not be formed on the stamped texture structure of the metal electrode.

[0051] In the example of FIG. 5, the electrical insulation spacer 104 is shown to define an opening having an inner wall of the spacer 104. In some embodiments, such an electrical insulation spacer can be, for example, a ceramic spacer.

[0052] FIG. 5 shows that in some embodiments, an electrical insulation seal can be provided for each of the first and second electrodes 102a, 102b. For example, the first electrical insulation seal 106a (e.g., a glass seal) can be mounted on the silver ink layer 122a so as to laterally surround the discharge part including the silver texture layer 124a and the radiation coating layer 126a. In another example, in the context of the above-described stamped metal electrode configuration, the first electrical insulation seal 106a (e.g., a glass seal) can be mounted on the metal electrode itself so as to laterally surround the discharge part including the stamped texture structure and the radiation coating layer (when mounted). Such an electrical insulation seal can be dimensioned such that its lateral inner edge defines the outer edge of the discharge part and its lateral outer part engages the corresponding surface (e.g., the upper surface) of the electrical insulation spacer 104. Thus, it is shown that the outer edge of the discharge part of the first electrode 102a is laterally separated from the inner wall of the opening of the electrical insulation spacer 104 by the electrical insulation material of the first seal 106a.

[0053] Similarly, the second electrical insulation seal 106b (e.g., a glass seal) can be mounted on the silver ink layer 122b so as to laterally surround the discharge part including the silver texture layer 124b and the radiation coating layer 126b. In the context of the above-described stamped metal electrode configuration, the second electrical insulation seal 106b (e.g., a glass seal) can be mounted on the metal electrode itself so as to laterally surround the discharge part including the stamped texture structure and the radiation coating layer (when mounted). Such an electrical insulation seal can be dimensioned such that its lateral inner edge defines the outer edge of the discharge part and its lateral outer part engages the corresponding surface (e.g., the lower surface) of the electrical insulation spacer 104. Thus, it is shown that the outer edge of the discharge part of the second electrode 102b is laterally separated from the inner wall of the opening of the electrical insulation spacer 104 by the electrical insulation material of the second seal 106b. It will be understood that the first and second electrical insulation seals 106a, 106b may or may not be the same.

[0054] By configuring as described above, the inner wall of the opening of the spacer 104, the lateral inner portions of the first and second electrical insulation seals 106a, 106b, and the discharge portions of the first and second electrodes 102a, 102b are shown to define the sealed chamber 108. As described herein, such a sealed chamber can be filled with a gas or a mixture of gases to provide a desired discharge function.

[0055] In the example of FIG. 5, it is shown that the inner wall of the opening of the spacer 104 is recessed laterally from the outer edges of the first and second discharge portions (by, for example, the lateral dimension of the lateral inner portions of the first and second electrical insulation seals 106a, 106b). Thus, such lateral dimensions associated with each of the first and second electrical insulation seals 106a, 106b can contribute to an increase in the leak path length between the discharge portions of the first and second electrodes 102a, 102b.

[0056] In the example of FIG. 5, the lateral outer portion of the spacer 104 is shown to extend laterally beyond the walls defined by the first and second electrodes 102a, 102b. In some embodiments, as described herein, such a lateral extension of the spacer 104 can be utilized to facilitate the manufacture of a plurality of GDTs. Also, as described herein, the lateral extension of the spacer 104 as an outer wing-like structure can also form a longer leak path outside the corresponding GDT.

[0057] In the example of FIG. 5, a single electrical insulation structure (e.g., a glass seal) contributes to both the sealing function (between one electrode and the corresponding face of the spacer) and the lateral increase in the leak path length (inner and / or outer). In some embodiments, it is also possible to implement any or both of such functions in different ways.

[0058] For example, FIG. 6 shows that in some embodiments, the GDT 100 can separately include a structure for providing a sealing function and a structure for providing a lateral increase in the leakage path length. In the example of FIG. 6, each of the first and second electrodes 102a, 102b can include a metal sheet (120a or 120b) (e.g., a stamped flat metal sheet), and one or more layers can be formed on such a metal sheet to provide a discharge portion. For example, a radiation coating layer (126a or 126b) can be formed on the central portion of the metal sheet (120a or 120b) so as to form a discharge portion at the central portion of the electrode (102a or 102b). It will be understood that such a discharge portion can be formed symmetrically with respect to the center line extending between the first and second electrodes 102a, 102b, or can be formed asymmetrically away from the central portion.

[0059] In the example of FIG. 6, an electrical insulation layer can be provided for each of the first and second electrodes 102a, 102b. For example, a first electrical insulation layer 130a (e.g., a glass layer) can be mounted on the metal sheet 120a so as to laterally surround the discharge portion including the radiation coating layer 126a. Such an electrical insulation layer can be dimensioned to laterally separate the outer edge of the radiation coating layer 126a from the inner wall of the opening defined by the electrical insulation spacer 104. It should be noted that the first electrical insulation layer 130a does not provide a sealing function between the electrical insulation spacer 104 and the metal sheet 120a of the first electrode 102a. Also, in some embodiments, it should be noted that the first electrical insulation layer 130a and the electrical insulation spacer 104 can be configured such that the joint between them does not allow a part of the metal sheet 120a to overflow from the joint and damage the leakage path. In some embodiments, such a joint can include a configuration in which the outer portion of the first electrical insulation layer 130a is sufficiently engaged with the inner portion of the electrical insulation spacer 104 to prevent damage to the leakage path between the first electrical insulation layer 130a and the electrical insulation spacer 104.

[0060] Similarly, a second electrical insulating layer 130b (e.g., a glass layer) can be mounted on the metal sheet 120b so as to laterally surround the discharge portion including the radiation coating layer 126b. Such an electrical insulating layer can be dimensioned to laterally separate the outer edge of the radiation coating layer 126b from the inner wall of the opening defined by the electrical insulating spacer 104. It should be noted that the second electrical insulating layer 130b does not provide a sealing function between the electrical insulating spacer 104 and the metal sheet 120b of the second electrode 102b. Also, in some embodiments, it should be noted that the second electrical insulating layer 130b and the electrical insulating spacer 104 can be configured such that the joint therebetween does not allow a part of the metal sheet 120b to overflow from the joint and damage the leakage path. In some embodiments, such a joint can include a configuration in which the outer portion of the second electrical insulating layer 130b sufficiently engages with the inner portion of the electrical insulating spacer 104 to prevent damage to the leakage path between the second electrical insulating layer 130b and the electrical insulating spacer 104.

[0061] By configuring as described above, the first and second electrical insulating layers 130a, 130b can cause a respective lateral increase in the leakage path length between the first and second electrodes 102a, 102b.

[0062] In the example of FIG. 6, it is shown that the sealing function is provided by a structure other than the electrical insulating layers 130a and 130b. For example, the sealing assembly between one surface of the electrical insulating spacer 104 (e.g., the upper surface when oriented as in FIG. 6) and the first metal sheet 120a can include a bonding surface layer 132a (e.g., CuSil alloy brazing metal) formed on the first metal sheet 120a and a bonding surface layer 134a (e.g., tungsten metallized layer) formed on the electrical insulating spacer 104. Similarly, the sealing assembly between the other surface of the electrical insulating spacer 104 (e.g., the lower surface) and the second metal sheet 120b can include a bonding surface layer 132b (e.g., CuSil alloy brazing metal) formed on the second metal sheet 120b and a bonding surface layer 134b (e.g., tungsten metallized layer) formed on the electrical insulating spacer 104.

[0063] Note that in the example of FIG. 6, each of the sealing assemblies (e.g., 132a / 134a and 132b / 134b) can be either conductive or non - conductive. Even if the sealing assembly is conductive, the sealing assembly is electrically insulated from the leakage path between the discharge portions of the two electrodes 102a and 102b.

[0064] In some embodiments, the above - described sealing assemblies can provide a sealing function by joining the respective bonding surface layers (e.g., by applying heat) during the manufacturing process. The inner wall of the spacer 104, the first and second electrical insulating layers 130a and 130b, and the first and second discharge portions are shown to define a sealed chamber 108 when sealed. As described herein, such a sealed chamber can be filled with a gas or a mixture of gases to provide the desired discharge function.

[0065] Note that in the example of FIG. 6, the spacer 104 is an electrically insulating spacer (e.g., a ceramic spacer). Thus, the bonding surface layers 132, 134 can be an electrically insulating layer, a conductive layer, or some combination thereof. When the bonding surface layers 132, 134 are formed of a conductive material, such layers provide a sealing function but should be formed so as to be sufficiently separated from the inner wall of the opening of the spacer 104 so as not to impede the electrical characteristics associated with the first and second electrodes 102a, 102b.

[0066] In the examples of FIGS. 5 and 6, each GDT is configured to have a single electrode on one side of the spacer and another single electrode on the other side of the spacer. FIG. 7 shows that in some embodiments, a GDT having one or more of the features described herein can include two or more electrodes on a given side of the spacer. FIG. 7 also shows that in some embodiments, the spacer in a GDT having one or more of the features as described herein can include two or more layers.

[0067] For example, referring to FIG. 7, two electrodes 102a, 102b are mounted on one side of the spacer assembly (e.g., the upper side when oriented as in FIG. 7), and one electrode 102c is mounted on the other side of the spacer assembly. The spacer assembly is shown to include a first layer 127a and a second layer 127c. Such layers can be an electrically insulating layer such as a ceramic layer and can be joined by a sealing layer 129 such as a glass seal. The first layer 127a is depicted as including an intermediate portion 127b that supports the laterally separated upper electrodes 102a, 102b. In some embodiments, the intermediate portion 127b may or may not be connected to the lateral outer portion of the first layer 127a.

[0068] By configuring as described above, the outer lateral portions of the respective electrodes 102a, 102b are shown to fit with the outer lateral portions of the first layer 127a, and the inner lateral portions of the respective electrodes 102a, 102b are shown to fit with the intermediate portion 127b. In the example of FIG. 7, each of the electrodes 102a, 102b can include individual layers similar to those in the example of FIG. 5 in order to form their respective discharge portions. Further, the sealing portions 125a, 125b similar to those in the example of FIG. 5 can provide a sealing function and an increase in the leak path length.

[0069] In the example of FIG. 7, the lower electrode 102c is configured in a manner similar to that in the example of FIG. 5 and can fit with the second layer 127c. By configuring as shown in FIG. 7, the leak paths associated with any portion of the discharge portions of the three examples (associated with the three electrodes 102a, 102b, 102c) can be increased by a part of the respective sealing structures (e.g., 125a or 125c) by forming a lateral offset with respect to the innermost wall of the insulating layer (e.g., 127a or 127c).

[0070] In the examples of FIGS. 5 to 7, each GDT includes a single sealed chamber. However, it will be understood that a GDT having one or more features as described herein can include two or more sealed chambers. In such a configuration having a plurality of sealed chambers, at least one sealed chamber can be associated with an increased leak path length as described herein.

[0071] FIGS. 8A to 8J show various stages of a process that can be used to manufacture the exemplary GDT 100 of FIG. 5. FIGS. 8A and 8B relate to the electrical insulation spacer 104, FIGS. 8C to 8G relate to each electrode (102a or 102b), and FIGS. 8H to 8J relate to the assembly of the electrodes to the electrical insulation spacer.

[0072] FIG. 8A is a side view of an electrical insulating spacer 104 (e.g., a ceramic spacer) having an opening 200. In some embodiments, such an opening can be formed in a subsequent step or can be formed beforehand. For the description of FIGS. 8A-8J, the electrical insulating spacer 104 may be a ceramic spacer, but it will be understood that such an electrical insulating spacer can be formed of other materials.

[0073] FIG. 8B shows the step of forming a glass layer 202a on one side of the ceramic spacer 104 and a glass layer 202b on the other side of the ceramic spacer 104 to produce an assembly 204. Examples related to the formation of such glass layers are described in U.S. Patent Application Publication No. 2019 / 0074162 entitled "GLASS SEALED GAS DISCHARGE TUBES", which is hereby expressly incorporated by reference in its entirety and the disclosure thereof is considered a part of this specification. It will be understood that layers 202a, 202b can be formed of other materials including non-glass insulating materials.

[0074] FIG. 8C is a side view of a metal sheet 120 used as an electrode. In some embodiments, such a metal sheet can be stamped from a larger metal sheet or strip.

[0075] FIG. 8D shows the step of forming a silver ink layer 122 on one side of the metal sheet 120 to produce an assembly 206. In some embodiments, such a silver ink layer can be formed, for example, by performing a curing step after printing or spraying. In some embodiments, this step can be omitted in a configuration where the electrode is implemented as a stamped metal structure as described herein with reference to FIG. 5.

[0076] Figure 8E shows the step of forming a glass layer 208 on the silver ink layer 122 to generate the assembly 210. In some embodiments, such a glass layer can be formed around the outer edge of the silver ink layer 122 with a width dimension that increases the leak path length as described herein. In some embodiments, as described herein with reference to FIG. 5, the glass layer 208 can be formed around the outer edge of the metal sheet 120 (e.g., directly on the metal sheet 120) in a configuration where the electrodes are mounted as a stamped metal structure.

[0077] Figure 8F shows the step of forming a silver texture layer 124 on the silver ink layer 122 such that it is provided laterally between the glass layers 122 along the outer edge to generate the assembly 212. In some embodiments, as described herein with reference to FIG. 5, the silver texture layer 124 can be omitted, and instead, a similar texture structure can be formed on the metal sheet 120 (e.g., a stamped structure) in a configuration where the electrodes are mounted as a stamped metal structure.

[0078] Figure 8G shows the step of forming a radiation coating layer 126 on the silver texture layer 124 (or on the stamped structure of the corresponding stamped metal electrode) such that it is provided laterally between the glass layers 122 along the outer edge to generate the assembly 214. The assembly 214 can be used as either the first or second electrode 102a, 102b in the example of FIG. 5.

[0079] Figure 8H is an assembly diagram showing that the assembly 204 of FIG. 8B is about to be sandwiched between two assemblies 214a, 214b of FIG. 8G. It will be understood that in some embodiments, the assemblies 214a, 214b can be fitted to the assembly 204 simultaneously, sequentially, or some combination thereof.

[0080] FIG. 8I shows an assembly diagram in which assembly 204 engages two assemblies 214a, 214b to produce assembly 220, and the mating joints (216a, 216b) have not yet been cured and sealed. Prior to or during the formation of such an assembly, a desired gas can be introduced into volume 218 that is to be sealed.

[0081] FIG. 8J shows an assembly diagram in which the mating joints (216a, 216b in FIG. 8I) are cured to produce a GDT 100 having a sealed chamber 108 and an increased leak path length that includes a portion of each seal and the inner wall of the opening of spacer 104, as described herein.

[0082] The example manufacturing steps of FIGS. 8A - 8J are described in the context of a single unit. It will be understood that a GDT having one or more features as described herein can be manufactured as a stand-alone unit, as a unit singly separated from an array of similar units, or as any combination thereof.

[0083] FIGS. 9A - 9J and FIGS. 10A - 10J show examples of various stages of a process that can be used to manufacture multiple GDT devices. FIGS. 9A - 9J are plan views of an array or group of singulated units, and FIGS. 10A - 10J are side views (side cross-sectional views when shown) thereof.

[0084] For the description of FIGS. 9A - 9J and FIGS. 10A - 10J, each of such GDT devices is similar to the exemplary GDT 100 of FIG. 5. However, it will be understood that one or more features of such techniques can also be used to manufacture multiple GDTs having other configurations.

[0085] Figures 9A, 9B, 10A, and 10B relate to the array processing of the electrical insulation spacer 104. Figures 9C-9G and 10C-10G relate to the array processing of the electrodes (102a or 102b). Figures 9H-9J and 10H-10J relate to the array assembly processing of the electrodes onto the electrical insulation spacer.

[0086] For the electrical insulation spacer plate 300 (e.g., ceramic spacer) having a plurality of spacer units 104 that are not separately isolated, FIG. 9A shows a plan view and FIG. 10A shows a side cross-sectional view. Each of such spacer units would be similar to the spacer 104 of FIG. 8A if separately isolated. In FIG. 9A, each spacer unit 104 is shown to include an opening 200. In some embodiments, such an opening can be formed in a subsequent step or can be pre-formed. For the description of FIGS. 9A-9J and 10A-10J, the electrical insulation spacer plate 300 may be a ceramic spacer plate, but it will be understood that such an electrical insulation spacer plate can include other materials.

[0087] In FIG. 10A, a boundary 306 is depicted on the ceramic plate 300 that forms the edge of the unitized units. In some embodiments, separation at or near such a boundary can be facilitated by the separation structures 302, 304 (e.g., cut lines) shown in FIG. 9A. Such separation structures can be formed in a subsequent step, pre-formed, or formed in some combination thereof. In some embodiments, such separation structures can be formed on the ceramic plate 300 using one or more laser beams.

[0088] Figures 9B and 10B show the steps of forming a glass layer 202a for each spacer unit 104 on one surface of the ceramic spacer plate and forming a glass layer 202b for each spacer unit 104 on the other surface of the ceramic spacer plate to generate the assembly 308. Examples related to the formation of such glass layers are described in the above-mentioned U.S. Patent Application Publication No. 2019 / 0074162. It will be understood that the layers 202a, 202b can be formed of other materials including non-glass insulating materials.

[0089] FIG. 9C shows a plan view and FIG. 10C shows a side cross-sectional view of a metal sheet 310 having a plurality of units 120 that are not separately isolated. Each of such units is similar to the metal sheet 120 of FIG. 8C and can be used as an electrode.

[0090] FIGS. 9C and 10C are depicted such that the metal sheet 310 has boundaries 312, 314 that are the edges of the unified units 120. In some embodiments, the metal sheet 310 can be cut by stamping to form a plurality of unified units 120.

[0091] FIGS. 9D and 10D show the steps of forming a silver ink layer 122 for each unit 120 on one surface of the metal sheet 310 to generate the assembly 316. In some embodiments, such a silver ink layer can be formed, for example, by performing a curing step after printing or spraying. In some embodiments, this step can be omitted in a configuration where the electrodes are implemented as a stamped metal structure as described herein with reference to FIG. 5.

[0092] Figures 9E and 10E show the step of forming a glass layer 208 for each unit 120 on the silver ink layer 122 to generate the assembly 322. In some embodiments, such a glass layer can be formed around the periphery of the silver ink layer 122 with a width dimension that increases the leakage path length, as described herein. In some embodiments, as described herein with reference to FIG. 5, the glass layer 208 can be formed around the periphery of each unit 120 (e.g., directly on the metal) in a configuration where the electrodes are mounted as a stamped metal structure.

[0093] Figures 9F and 10F show the step of forming a silver texture layer 124 and a radiation coating layer 126 for each unit 120 on the silver ink layer 122 such that they are provided laterally between the glass layers 208 along the periphery to generate the assembly 324. In some embodiments, the silver texture layer 124 can be omitted, and instead, in a configuration where the electrodes are mounted as a stamped metal structure, a similar texture structure (e.g., a stamped structure) can be formed on the metal of each unit 120, as described herein with reference to FIG. 5.

[0094] Figures 9G and 10G show the step of separating the assembly 324 of FIGS. 9F and 10F into a single unit along the boundaries 312, 314 to form a plurality of unitized units 214. Each of the unitized units 214 can be used as either the first or second electrode 102a, 102b in the example of FIG. 5.

[0095] Figures 9H and 10H show an assembly diagram in which each unit 104 of the assembly 308 of FIGS. 9B and 10B is sandwiched between two unitized units 214a, 214b of FIGS. 9G and 10G to generate the assembly 330. It will be understood that in some embodiments, the unitized units 214a, 214b can be fitted to each unit 104 simultaneously, sequentially, or some combination thereof.

[0096] In the examples of FIGS. 9H and 10H, the mating joints are not yet cured and sealed. Prior to or during the sealing process, a desired gas can be introduced into the volume 218 associated with each unit 104.

[0097] FIGS. 9I and 10I show an assembled view in which the mating joints are cured to obtain a plurality of unitized GDT units 220 for generating the assembly 332. Each such non-unitized GDT unit is shown to include a sealed chamber 108 and an increased leak path length including a portion of each of the insulating seals 106a, 106b, as described herein.

[0098] FIGS. 9J and 10J show the step of separating the assembly 332 of FIGS. 9I and 10I along the boundaries (312, 314 in FIG. 9A) to provide a plurality of unitized GDTs 100. Each of the unitized GDTs 100 can be similar to the example of FIG. 5.

[0099] In the examples of FIGS. 9A - 9J and FIGS. 10A - 10J, the lateral shape of the GDT is depicted as rectangular. Such a shape can enable the single separation of the fabricated units, for example, by snapping facilitated by cut lines on the corresponding spacer plate. Also, such a GDT is depicted as having electrodes associated with a rectangular chamber. Thus, in such a configuration, the electrical insulating layer that increases the leak path length associated with each electrode can have a rectangular-shaped ring surrounding the corresponding discharge portion of the electrode. It will be understood that a GDT having one or more of the features described herein can include other lateral shapes including a circular shape. It will also be understood that different portions of a GDT having one or more of the features described herein can have different lateral shapes. For example, the spacer can have a rectangular shape and its opening can have a circular shape. In such a configuration, the corresponding electrodes and related parts such as insulating seals can have a circular shape.

[0100] In the various examples described with reference to FIGS. 2-10, a spacer is used between a pair of opposing electrodes, and the thickness of the spacer forms part of the leakage path length. Such a leakage path length is shown to be increased by implementing an electrical insulating layer that laterally surrounds the discharge portions of the respective electrodes, whereby the leakage path length representing the dimension between the edge of the discharge portion and the inner wall of the opening of the spacer is increased. As described herein, such an electrical insulating layer can be configured to provide a sealing function (e.g., as in the example of FIG. 5), or can be configured to primarily provide separation between the discharge portion and the inner wall of the spacer.

[0101] Thus, it will be appreciated that a GDT having one or more of the features described herein can have an increased leakage path length whether or not there is a spacer between a pair of opposing electrodes. For example, FIGS. 11-13 show various examples of GDTs each having a sealed chamber formed by a pair of opposing electrodes joined and sealed by a sealing structure without using a separate spacer. It should be noted that in some embodiments, such a configuration of the GDT may be desirable regardless of the presence or absence of an increased leakage path length.

[0102] FIG. 11A shows that in some embodiments, the GDT 400 can include first and second electrodes 402a, 402b having flat surfaces facing each other and separated by a gap dimension d gap . Such first and second electrodes can be implemented, for example, as flat metal sheets. In the example of FIG. 11A, an electrical insulating sealing structure 406 (e.g., a glass seal) is shown to join and seal the outer periphery of the electrodes 402a, 402b to form a sealed chamber 408. Thus, the leakage path 409 between the first and second electrodes 402a, 402b is essentially the dimension of the wall of the sealed chamber 408 defined by the insulating sealing structure 406.

[0103] Similarly, FIG. 11B shows that in some embodiments, the GDT 410 can include first and second electrodes 412a, 412b having flat surfaces facing each other and separated by a gap dimension d gap . Such first and second electrodes can be implemented, for example, as flat metal sheets. In the example of FIG. 11B, an electrical insulating seal structure 416 (e.g., a glass seal) is shown to join and seal the outer periphery of the electrodes 412a, 412b so as to form a sealed chamber 418. Accordingly, the leakage path 419 between the first and second electrodes 412a, 412b is essentially the dimension of the wall of the sealed chamber 418 defined by the insulating seal structure 416. In the example of FIG. 11B, it is shown that the insulating seal structure 416 has a lateral dimension that is significantly larger than the lateral dimension of the insulating seal structure 406 in the example of FIG. 11A.

[0104] Referring to the examples of FIGS. 11A and 11B, assuming that the respective gap dimensions (d gap ) are the same, it can be seen that just increasing the lateral dimension of the insulating seal structure does not result in an increase in the leakage path length with respect to the gap dimension (d gap ). More specifically, in the examples of FIGS. 11A and 11B, for each GDT, the ratio of the leakage path length (substantially the same as the height of the wall) to the gap dimension (d gap ) is essentially the same.

[0105] FIG. 12A shows that in some embodiments, the GDT 420 can include first and second electrodes 422a, 422b having undulating surfaces (e.g., concave surfaces) facing each other and a shortest separation gap dimension d gap . In the example of FIG. 12A, an electrical insulating seal structure 426 (e.g., a glass seal) is shown to join and seal the outer periphery of the electrodes 422a, 422b so as to form a sealed chamber 428. Accordingly, the leakage path 429 between the first and second electrodes 422a, 422b is essentially the dimension of the wall of the sealed chamber 428 defined by the insulating seal structure 426.

[0106] Similarly, FIG. 12B shows that in some embodiments, the GDT 430 can include first and second electrodes 432a, 432b having undulating surfaces (e.g., concave surfaces) facing each other and a shortest separation gap dimension d gap In the example of FIG. 12B, an electrical insulation sealing structure 436 (e.g., a glass seal) is shown to bond and seal the outer perimeters of the electrodes 432a, 432b so as to form a sealed chamber 438. Thus, the leakage path 439 between the first and second electrodes 432a, 432b is essentially the dimension of the wall of the sealed chamber 438 defined by the insulation sealing structure 436. In the example of FIG. 12B, it is shown that the insulation sealing structure 436 has a lateral dimension that is significantly larger than the lateral dimension of the insulation sealing structure 426 in the example of FIG. 12A.

[0107] Referring to the examples of FIGS. 12A and 12B and assuming that the concave surfaces of the respective GDTs have similar dimensions, increasing the lateral dimension of the insulation sealing structure 436 in FIG. 12B results in a significant increase in the dimension of the wall of the chamber 438 (defined by the insulation sealing structure 436), and thus the leakage path length, compared to the wall dimension / leakage path length of the GDT in FIG. 12A. However, in the example of FIG. 12B, the shortest separation gap dimension d gap also increases significantly compared to the shortest separation gap dimension d gap in the example of FIG. 12A. Thus, it can be seen that simply increasing the dimension of the insulation sealing structure does not necessarily increase the leakage path length with respect to the gap dimension (d gap ). More specifically, in the examples of FIGS. 12A and 12B, each GDT has a similar ratio of its respective leakage path length to the gap dimension (d gap ).

[0108] FIG. 13 shows a GDT440 having an electrode configuration similar to the examples of FIGS. 12A and 12B. In the example of FIG. 13, an electrical insulation sealing structure 446 (e.g., a glass seal) is shown to join and seal the outer perimeters of the first and second electrodes 442a, 442b so as to form a sealed chamber 448. The electrical insulation sealing structure 446 is shown to further include individual covering portions for each of the first and second electrodes 442a, 442b. More specifically, a first covering portion is shown to extend from the sealing portion of the electrical insulation sealing structure 446 so as to cover at least a part of the concave shape of the inward-facing surface of the first electrode 442a. Similarly, a second covering portion is shown to extend from the sealing portion of the electrical insulation sealing structure 446 so as to cover at least a part of the concave shape of the inward-facing surface of the second electrode 442b. Thus, the leakage path 449 between the first and second electrodes 442a, 442b is shown to include the respective extension lengths of the first and second covering portions of the electrical insulation sealing structure 446, rather than being essentially similar to the dimensions of the straight walls of the sealed chamber as in the example of FIG. 12B.

[0109] In the example of FIG. 13, each concave surface of each electrode is shown to include an inner portion (441a or 441b) and an outer portion (443a or 443b). Such inner and outer portions can have a linear shape as shown in FIG. 13, but it will be understood that in some embodiments, either or both of the inner and outer portions can have a curved shape.

[0110] In the example of FIG. 13, each covering portion of the electrical insulation sealing structure 446 extends inwardly to cover the entire outer portion (443a or 443b) and a part of the inner portion (441a or 441b) so as to form an exemplary leakage path 449, with the end of the covering portion defining a gap dimension d gap If each covering portion is sized to cover only a part of the respective outer portion (443a or 443b), the resulting gap dimension d gapNote that this can be the separation distance between the two electrodes 442a, 442b at the end of the coated portion. In such a configuration, the ratio of the leakage path length to the resulting gap dimension may or may not be sufficient for the desired GDT configuration.

[0111] Accordingly, in some embodiments, the electrical insulation encapsulation structure can include discrete coated portions that extend a selected distance along the concave surface of each electrode to provide a desired ratio of leakage path length to gap dimension. In some embodiments, each coated portion of the electrical insulation encapsulation structure can extend partially along the respective outer portion (443a or 443b) of the concave surface, such that the entire inner portion (441a or 441b) is not covered. In some embodiments, each coated portion of the electrical insulation encapsulation structure can extend to substantially cover the respective outer portion (443a or 443b) of the concave surface, leaving the inner portion (441a or 441b) substantially uncovered. In some embodiments, each coated portion of the electrical insulation encapsulation structure can extend to cover the respective outer portion (443a or 443b) of the concave surface and also cover a portion of the inner portion (441a or 441b), such that the remaining portion of the inner portion remains uncovered.

[0112] Based at least on various examples provided herein, in some embodiments, a gas discharge tube (GDT) can include first and second electrodes each including an inward-facing surface, where the inward-facing surfaces of the first and second electrodes are oriented to face each other. The GDT can further include a seal implemented to join and seal edge portions of the inward-facing surfaces of the first and second electrodes to define a sealed chamber between the inward-facing surfaces of the first and second electrodes. The GDT can further include an electrical insulation layer implemented to cover a portion of each of the inward-facing surfaces of at least one of the first and second electrodes to define a discharge portion on each inward-facing surface not covered by the electrical insulation layer, whereby the sealed chamber is further defined by the surface of the electrical insulation layer and the discharge portions of the respective electrodes, and further whereby leak paths within the sealed chamber are configured to include the surface of the electrical insulation layer and the walls of the sealed chamber.

[0113] Note that in various examples described herein, the seal of the GDT can include a seal member and may or may not include a spacer. For example, each GDT shown in FIGS. 2-7 includes one or more spacers. In such a configuration, the walls of the sealed chamber can include the walls of the openings of each of the one or more spacers. In other examples, the GDT shown in FIG. 13 does not include a separate spacer. In such a configuration, the walls of the sealed chamber can include portions where at least one electrical insulation layer joins the seal member (e.g., if only one electrical insulation layer is provided) or another electrical insulation layer (e.g., if electrical insulation layers are provided on both inward-facing surfaces).

[0114] Also note that in various examples depicted in the figures, it is shown that an electrical insulation layer is provided on each of the first and second electrodes, thereby increasing the internal leak path length of each respective GDT. In some embodiments, it will be understood that a GDT having one or more features as described herein can still have its internal leak path length increased even if only one electrode is provided with an electrical insulation layer.

[0115] In some embodiments, a GDT having one or more of the features described herein can be used by itself, for example, as a circuit protection device. In some embodiments, a GDT having one or more of the features as described herein can be combined with other devices or components.

[0116] For example, FIGS. 14 and 15 show that in some embodiments, a GDT having one or more of the features as described herein can be combined with one or more electrical devices or components to produce a circuit protection device. For example, FIG. 14 shows a circuit protection 500 in which GDT 100 is coupled (e.g., in series) to a clamping device 502. Such a coupling of GDT 100 and clamping device 502 can be made via one or more conductive paths (e.g., wires) or such that the two devices physically contact each other.

[0117] In another example, FIG. 15 shows a circuit protection device 500 in which GDT 100 is coupled to a first clamping device 502a on one side and to a second clamping device 502b on the other side. In some embodiments, such an arrangement can be made in series. In some embodiments, each such coupling of GDT 100 and clamping devices 502a, 502b can be made via one or more conductive paths (e.g., wires) or such that the coupled devices physically contact each other.

[0118] FIG. 16 shows a circuit protection device 500 that can be a more specific example of the circuit protection device 500 of FIG. 14, and FIG. 17 shows a circuit protection device 500 that can be a more specific example of the circuit protection device 500 of FIG. 15.

[0119] FIG. 16 shows that in some embodiments, the circuit protection device 500 can include a GDT portion 100 and a varistor portion 502. In some embodiments, such a varistor portion can be configured as a metal oxide varistor (MOV) having a metal oxide layer 512 mounted between electrodes 510 and 514. Electrode 514 is shown to be a common electrode between MOV 502 and GDT 100. Thus, common electrode 514 is also shown as the first electrode 522a of GDT 100. GDT 100 is shown to further include a second electrode 522b such that a sealed chamber 528 exists between the first and second electrodes 522a, 522b.

[0120] In the example of FIG. 16, each of the first and second electrodes 522a, 522b is shown to include a concave surface similar to the example of FIG. 13. Also, similar to the example of FIG. 13, the first and second electrodes 522a, 522b are shown to be joined and sealed by an insulating seal structure 526 configured to form separate coating portions on each of the first and second electrodes 522a, 522b. More specifically, a first coating portion 527a is shown to cover the edge portion of the concave surface of the first electrode 522a, and a second coating portion 527b is shown to cover the edge portion of the concave surface of the second electrode 522b. Thus, as described herein, such separate coating portions can result in a desirable increase in the internal leakage path length between the first and second electrodes 522a, 522b.

[0121] In the example of FIG. 16, the concave surface of each of the first and second electrodes 522a, 522b not covered by the respective coating portion (527a or 527b) can be the discharge portion of the respective electrode. As described herein, such a discharge portion may or may not include one or more layers (524a, 524b) such as a silver texture layer or a radiation coating layer.

[0122] In the example of FIG. 16, the common electrodes 514 / 522a are shown to form the concave surface of the GDT 100. The other surface of the common electrodes 514 / 522a is shown to form a convex surface having an edge portion that extends away from the other electrode 510 of the MOV 502. Such a configuration of the extended edge can desirably reduce the possibility of damage to the MOV 502 at or near the edge portion.

[0123] FIG. 17 shows that in some embodiments, the circuit protection device 500 can include a GDT portion 100 and varistor portions on both surfaces of the GDT portion 100. Thus, it is shown that the first varistor 502a is on the first surface of the GDT portion 100, and the second varistor 502b is on the second surface of the GDT portion 100.

[0124] In some embodiments, such varistor portions can each be configured as a metal oxide varistor (MOV). Thus, it is shown that the first MOV 502a has a first metal oxide layer 512a mounted between the electrodes 510a and 514a. The electrode 514a is shown to be a common electrode between the MOV 502a and the GDT 100. Thus, the common electrode 514a is also shown as the first electrode 522a of the GDT 100. The GDT 100 is shown to further include a second electrode 522b such that there is a sealed chamber 528 between the first and second electrodes 522a, 522b.

[0125] In the example of FIG. 17, each of the first and second electrodes 522a and 522b is shown to include a concave surface similar to the example of FIG. 13. Also, similar to the example of FIG. 13, the first and second electrodes 522a and 522b are shown to be joined and sealed by an insulating seal structure 526 configured to form separate coating portions on each of the first and second electrodes 522a and 522b. More specifically, the first coating portion 527a is shown to cover the edge portion of the concave surface of the first electrode 522a, and the second coating portion 527b is shown to cover the edge portion of the concave surface of the second electrode 522b. Thus, as described herein, such separate coating portions can result in a desirable increase in the internal leakage path length between the first and second electrodes 522a and 522b.

[0126] In the example of FIG. 17, each of the concave surfaces of the first and second electrodes 522a and 522b not covered by their respective coating portions (527a or 527b) can serve as the discharge portions of their respective electrodes. As described herein, such discharge portions may or may not include one or more layers (524a, 524b) such as a silver texture layer or a radiation coating layer.

[0127] In the example of FIG. 17, the first common electrode 514a / 522a is shown to form the concave surface of the first face of the GDT100, and the second common electrode 514b / 522b is shown to form the concave surface of the second face of the GDT100. The other face of the first common electrode 514a / 522a is shown to form a convex surface having an edge portion that extends away from the other electrode 510a of the first MOV502a. Such a configuration of the extended edge can desirably reduce the possibility of damage to the first MOV502a at the edge portion or in its vicinity. Similarly, the other face of the second common electrode 514b / 522b is shown to form a convex surface having an edge portion that extends away from the other electrode 510b of the second MOV502b. Such a configuration of the extended edge can desirably reduce the possibility of damage to the second MOV502b at the edge portion or in its vicinity.

[0128] For the purposes of the description in this specification, the concave surface can include a central portion and an edge portion, and the edge portion extends parallel to the plane defined by the central portion toward the plane on the side facing the concave surface. Similarly, the convex surface can include a central portion and an edge portion, and the edge portion extends parallel to the plane defined by the central portion away from the plane on the side facing the convex surface. The edge portion can include a shape having one or more straight portions, one or more curved portions, or some combination thereof.

[0129] Figures 18A - 18H show various stages of a process that can be used to manufacture a plurality of circuit protection devices such as the circuit protection device 500 of FIG. 17. In some embodiments, such a manufacturing process can include at least a portion of the process steps that are performed while a plurality of units are attached in an array format.

[0130] FIG. 18A shows a process step in which a metal oxide plate 552 can be provided or formed. Such a plate is shown to include a plurality of units 550, each of which will ultimately be a circuit protection device having the functions of a GDT and an MOV.

[0131] In the process step of FIG. 18B, a recess 554 formed on one surface of the metal oxide 552 of each unit 550 can be formed to form an assembly 556.

[0132] In the process step of FIG. 18C, in order to form the assembly 562, the electrode 558 can be formed on the metal oxide 552 so as to partially or completely cover the formed depression (554 in FIG. 18B) of each unit 550. In some embodiments, such an assembly can further include a radiation coating 560 formed on the inner lateral portion of the electrode 558. It will be understood that in some embodiments, the radiation coating 560 may or may not be used. Note that the electrode 558 includes an inner portion and an outer portion implemented as described herein.

[0133] In the process step of FIG. 18D, in order to form the assembly 566, a layer 564 of a sealing material can be formed around each unit 550 of the assembly 562. In some embodiments, such a sealing layer 564 can be formed of a material including glass, respectively.

[0134] In the process step of FIG. 18E, the inner portions of the two assemblies (566, 566') can be joined to assemble the two assemblies 566 of FIG. 18D. More specifically, the first assembly 566 (similar to the assembly 566 in FIG. 18D) can be inverted and placed on the second assembly 566' (which is also similar to the assembly 566 in FIG. 18D).

[0135] In the process step of FIG. 18F, in order to form the assembly 572, the assemblies (566 and 566') of FIG. 18E can be further processed to form a seal 568 for each unit and a corresponding sealed chamber 570.

[0136] In the process step of FIG. 18G, in order to form the assembly 580, the first and second external electrodes 574, 576 can be formed for each unit on the assembly 572 of FIG. 18F. In some embodiments, such external electrodes can have a lateral size that allows a single separation of each unit along the cut line 578.

[0137] In the process step of FIG. 18H, a plurality of units of the assembly 580 of FIG. 18G can be separated into a single unit to obtain a plurality of separate circuit protection devices 500 having GDT and MOV functions, and each circuit protection device is similar to the circuit protection device 500 of FIG. 17.

[0138] In some examples disclosed herein, including the examples of FIGS. 9, 10, and 18, it is described that a plurality of units are processed while in an array form. For the sake of explanation, an array can include an array of M×N units, where M is an integer greater than or equal to 1 and N is an integer greater than or equal to 1. Such an array of M×N units can be arranged, for example, in a single-row array form having a plurality of units in a single row, a single-column array form having a plurality of units in a single column, or a rectangular array form having a plurality of rows and a plurality of columns. It will be understood that an array can also include an arrangement configuration in which a plurality of units are arranged in a non-rectangular shape.

[0139] Unless the context clearly requires otherwise, throughout the specification and the claims, words such as "comprise," "comprising," and the like are to be construed in an inclusive sense, that is, in the sense of "including," rather than in an exclusive or exhaustive sense; that is, not limited to but including. Generally used herein, the term "coupled" means that two or more elements are directly connected or connected through one or more intermediate elements. Also, the phrases "herein," "above," "below," and similar phrases, when used in this application, refer to the whole of this application rather than any particular part of this application. Here, where the context permits, words in the singular or plural form in the specification can include the plural or singular respectively. The phrase "or" referring to a list of two or more items encompasses all of the following interpretations: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0140] The above detailed description of the embodiments of the present invention is not intended to be exhaustive, nor is it intended to limit the present invention to the detailed forms disclosed above. Specific embodiments of the present invention, and examples for the present invention, are described above for illustrative purposes, but as will be recognized by those of ordinary skill in the relevant art, various equivalent modifications are possible within the scope of the present invention. For example, although a process or block is shown in a given order, alternative embodiments may execute a routine having steps, or use a system having blocks in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or changed. Each of these processes or blocks may be implemented in a variety of different ways. Also, although a process or block may be shown as being executed serially, these processes or blocks may instead be executed in parallel, or at different times.

[0141] The teachings of the present invention provided herein are not necessarily limited to the systems described above, but can also be applied to other systems. The elements and operations of the various embodiments described above can be combined to provide further embodiments.

[0142] Although some embodiments of the present invention have been described, these embodiments are shown for illustrative purposes only and are not intended to limit the scope of the present disclosure. In fact, the novel methods and systems described herein may be implemented in a variety of other forms, and furthermore, various omissions, substitutions, and changes in the forms of the methods and systems described herein can be made without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or modifications that will fall within the scope and spirit of the present disclosure.

Claims

1. first and second electrodes, each including an edge and an inwardly facing surface, the inwardly facing surfaces of the first and second electrodes facing one another; a seal implemented to join and seal portions of the edges of the inwardly facing surfaces of the first and second electrodes to define a sealed chamber between the inwardly facing surfaces of the first and second electrodes; an electrical insulator forming a surface within the sealed chamber and mounted to cover a portion of the inwardly facing surface of each of at least one of the first and second electrodes, such that a leak path within the sealed chamber includes the surface of the electrical insulator; and A gas discharge tube (GDT) equipped with a

2. The GDT of claim 1 , wherein the electrical insulation is mounted to both of the first and second electrodes.

3. 2. The GDT of claim 1, further comprising a spacer mounted between the first and second electrodes, the spacer having a first surface and a second surface and defining an opening having an inner wall extending from the first surface to the second surface, such that the sealed chamber is further defined by the inner wall.

4. The GDT of claim 3 , wherein the spacer is formed of an electrically insulating material.

5. The GDT of claim 4 , wherein the electrically insulating material of the spacer comprises a ceramic material.

6. The GDT of claim 4 , wherein the leak path has a length greater than a thickness dimension of the spacer.

7. The GDT of claim 4 , wherein the leak path has a length that includes the sum of a path associated with each electrical insulation portion and a thickness dimension of the spacer.

8. The GDT of claim 4 , wherein the encapsulation portion includes an encapsulation layer mounted between each of the first and second surfaces of the spacer and a corresponding one of the electrodes.

9. The GDT of claim 8 , wherein the encapsulation layer is formed of a conductive material.

10. 10. The GDT of claim 9, wherein each electrical insulator extends laterally inward from the inner wall of the opening in the spacer, and each of the sealing layers is separated from the electrical insulator by the electrically insulating material of the spacer.

11. The GDT of claim 8 , wherein the encapsulation layer is formed of an electrically insulating material.

12. The GDT of claim 11 , wherein each of the electrical insulation portions is also formed from the electrical insulation material of the encapsulation layer.

13. The GDT of claim 12 , wherein each of the electrical insulation and encapsulation layers form a continuous structure.

14. The GDT of claim 11 , wherein the electrically insulating material of the sealing layer comprises glass.

15. The GDT of claim 4 , wherein the spacer is sized to extend laterally from the inner wall to an outer wall that is generally coplanar with outer edges of the first and second electrodes.

16. The GDT of claim 4 , wherein the spacer is sized to extend laterally from the inner wall to an outer wall laterally beyond outer edges of the first and second electrodes.

17. 17. The GDT of claim 16, wherein the spacer includes a notch structure at a corner of the outer wall of at least one of the first and second sides, the notch structure resulting in separation of the spacer from other spacers.

18. 17. The GDT of claim 16, wherein the spacer extends laterally beyond the outer edges of the first and second electrodes to increase an external leakage path length between the first and second electrodes.

19. The GDT of claim 1 , wherein the sealing portion is formed of an electrically insulating material and configured to directly bond and seal the first and second electrodes without a spacer.

20. 20. The GDT of claim 19, wherein each electrical insulation portion extends laterally inward from the sealing portion.

21. 21. The GDT of claim 20, wherein each electrical insulator is also formed from the electrical insulator material of the sealing portion.

22. 22. The GDT of claim 21, wherein the electrical insulation portion and the sealing portion form a continuous structure.

23. 22. The GDT of claim 21, wherein the electrically insulating material of the seal comprises glass.

24. The GDT of claim 1 , wherein each of the first and second electrodes is formed from a metal layer.

25. 25. The GDT of claim 24, wherein each electrical insulation portion is sized to expose a discharge portion on the inwardly facing surface of the respective electrode.

26. 26. The GDT of claim 25, wherein the discharge portion of the electrode includes one or more layers mounted on the inwardly facing surface of the metal layer.

27. 27. The GDT of claim 26, wherein the one or more layers mounted on the inwardly facing surface of the metal layer include a silver ink layer.

28. 30. The GDT of claim 27, wherein the one or more layers mounted on the inwardly facing surface of the metal layer further comprises a silver texture layer on the silver ink layer.

29. 30. The GDT of claim 28, wherein the one or more layers mounted on the inwardly facing surface of the metal layer further comprises an emissive coating layer on the silver texture layer.

30. 26. The GDT of claim 25, wherein the discharge portion of the electrode includes a textured structure formed on the inwardly facing surface of the metal layer.

31. 31. The GDT of claim 30, wherein the textured structure comprises a stamped metal structure formed on the metal layer.

32. 32. The GDT of claim 31, wherein the discharge portion of the electrode further comprises an emissive coating layer on the textured structure.

33. 26. The GDT of claim 25, wherein the discharge portion and the portion of each of the inwardly facing surfaces covered by the electrical insulation portion are substantially flat.

34. 26. The GDT of claim 25, wherein the discharge portion and the portion of each of the inwardly facing surfaces covered by the electrical insulation portion form a concave surface.

35. 35. The GDT of claim 34, wherein the concave surface includes a substantially flat inner portion and an angled outer portion, such that at least a portion of the angled outer portion is covered by the respective electrical insulation.

36. 36. The GDT of claim 35, wherein substantially all of the angled outer portion is covered by the respective electrical insulation.

37. forming or providing first and second electrodes, each including an edge and an inwardly facing surface; covering a portion of the inwardly facing surface of each of at least one of the first and second electrodes with an electrically insulating material; bonding and sealing portions of the edges of the inwardly facing surfaces of the first and second electrodes to define a sealed chamber between the inwardly facing surfaces of the first and second electrodes, the bonding and sealing being such that a leak path within the sealed chamber includes a surface of an electrically insulating material; A method for manufacturing a gas discharge tube (GDT), comprising:

38. 38. The method of claim 37, wherein joining and sealing portions of the edges of the inwardly facing surfaces of the first and second electrodes includes providing an electrically insulating spacer between the first and second electrodes, the spacer having a first side and a second side and defining an opening having an inner wall extending from the first side to the second side, such that the sealed chamber is further defined by the inner wall.

39. 38. The method of claim 37, wherein joining and sealing portions of the edges of the inwardly facing surfaces of the first and second electrodes further comprises forming a sealing layer mounted between each of the first and second surfaces of the spacer and the corresponding electrode.

40. 38. The method of claim 37, wherein joining and sealing portions of the edges of the inwardly facing surfaces of the first and second electrodes comprises forming an electrical insulator formed of an electrically insulating material that directly joins and seals the first and second electrodes without a spacer.

41. providing or forming an electrically insulating plate defining an array of spacer units, each spacer unit having a first and second surface and defining an aperture having an inner wall extending from the first surface to the second surface; forming or providing first and second electrodes, each including an edge and an inwardly facing surface; covering a portion of the inwardly facing surface of each of at least one of the first and second electrodes with an electrically insulating material; sealing the opening of each spacer unit with the first and second electrodes, wherein portions of the edges of the inwardly facing surfaces of the first and second electrodes define a sealed chamber between the inwardly facing first and second electrodes and such that a leak path within the sealed chamber includes a surface of an electrically insulating material; A method for manufacturing a plurality of gas discharge tubes (GDTs), comprising:

42. 42. The method of claim 41, further comprising separating the array of spacer units into a plurality of separate units.

43. 42. The method of claim 41, further comprising providing or forming a metal sheet having an array of electrode units and separating the array of electrode units to provide the first and second electrodes.

44. a gas discharge tube (GDT) including first and second electrodes each including an edge and an inwardly facing surface, the inwardly facing surfaces of the first and second electrodes facing one another, the GDT further including a sealing portion mounted to join and seal a portion of the edges of the inwardly facing surfaces of the first and second electrodes to define a sealed chamber between the inwardly facing surfaces of the first and second electrodes, the GDT further including an electrical insulator mounted to form a surface within the sealed chamber and to cover a portion of the inwardly facing surface of each of at least one of the first and second electrodes, such that a leak path within the sealed chamber includes the surface of the electrical insulator; a first clamping device electrically connected to the first electrode of the GDT; A circuit protection device comprising:

45. 45. The circuit protection device of claim 44, wherein the first clamping device is connected directly to the first electrode.

46. 46. ​​The circuit protection device of claim 45, wherein the first clamp device is a metal oxide varistor (MOV) having first and second electrodes and a metal oxide layer mounted between the first and second electrodes.

47. 47. The circuit protection device of claim 46, wherein one of the first and second electrodes of the MOV is configured as a terminal of the circuit protection device, and the other electrode of the MOV is another electrode electrically connected to the first electrode of the GDT.

48. 47. The circuit protection device of claim 46, wherein one of the first and second electrodes of the MOV is configured as a terminal of the circuit protection device and the first electrode of the GDT is configured as the other electrode of the MOV.

49. 45. The circuit protection device of claim 44, further comprising a second clamp device electrically connected to the second electrode of the GDT.

50. 50. The circuit protection device of claim 49, wherein the second clamp device is a metal oxide varistor (MOV) having first and second electrodes and a metal oxide layer mounted between the first and second electrodes.

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