Pptc heater and material with stable power and self-limiting characteristics

Abstract

The electrical resistance heater can include a polymeric positive temperature coefficient (PPTC) material disposed to define a ring shape of the heater body; and an electrode assembly including two or more electrodes disposed in contact with the heater body at two or more locations, wherein the PPTC material includes a polymeric matrix defining a PPTC body and an electrically conductive filler component disposed in the polymeric matrix.

Description

Technical Field

[0001] The embodiments relate to the field of resistance heaters, and more specifically, to heaters based on PPTC materials. Background Technology

[0002] Polymer positive temperature coefficient (PPTC) devices are used in various applications as overcurrent or overtemperature protection devices, as well as current or temperature sensors. For PPTC materials, the resistance increases with temperature due to the thermal expansion of the polymer matrix containing dispersed conductive materials (fillers) (e.g., conductive metal particles, conductive carbon particles, or ceramic conductive phases). At the trip temperature, the polymer matrix may undergo a phase transition, such as a melt transition. As the conductive filler particles separate from each other, the conductive path is interrupted, and the resulting significant increase in polymer volume can lead to a sharp increase in resistance. Upon cooling, as the polymer volume shrinks, the resistivity of the PPTC material may recover to a relatively low value below the trip temperature. This characteristic makes PPTC materials suitable for applications such as resettable fuses. Generally, the overall conductivity and resistance of PPTC materials with increasing temperature depend on the content of the conductive filler. For high resistivity (10~10000 ohm-cm) PPTC materials, due to the lower content of conductive filler, the resistance tends to increase more significantly with temperature, even below the trip temperature. The increased resistance below the trip temperature will cause increased IR heating of the PPTC material, potentially leading to abnormal tripping of the PPTC device. Therefore, the use of known PPTC materials may be limited for applications where stable electrical operation below the trip temperature is useful.

[0003] This disclosure provides for this and other considerations. Summary of the Invention

[0004] In one embodiment, the resistance heater may include a polymeric positive temperature coefficient (PPTC) material configured to define an annulus of a heater body; and an electrode assembly including two or more electrodes configured to contact the heater body at two or more locations, wherein the PPTC material includes: a polymer matrix defining the PPTC body; and a conductive filler component disposed within the polymer matrix.

[0005] In another embodiment, the camera may include a transparent lens portion and a resistance heater disposed around the periphery of the transparent lens portion. The resistance heater may include a polymeric positive temperature coefficient (PPTC) material arranged in a plane in an annular shape and defining a heater body, wherein the PPTC material includes a polymer matrix defining the PPTC body and a conductive filler component disposed within the polymer matrix. The resistance heater may also include an electrode assembly comprising a bottom electrode located on a first side of the heater body and a top electrode disposed on a second side of the heater body opposite the first side. Attached Figure Description

[0006] Figure 1 A PPTC component according to an embodiment of the present disclosure is shown;

[0007] Figure 2 Another PPTC component according to an embodiment of the present disclosure is shown;

[0008] Figure 3 The resistance of an exemplary PPTC material at temperature is shown according to an embodiment of the present disclosure;

[0009] Figure 4 A schematic diagram of the processing of a PPTC component according to an embodiment of the present disclosure is shown;

[0010] Figure 5 An exemplary processing flow is described;

[0011] Figure 6A and Figure 6B Exemplary resistance and power curves based on the temperature of an exemplary resistance heater according to embodiments of the present disclosure are shown respectively.

[0012] Figure 7A and Figure 7B Exemplary resistance and power curves according to embodiments of the present disclosure are shown for the temperature of another exemplary resistance heater.

[0013] Figure 7C and Figure 7D Exemplary resistance and power curves according to embodiments of the present disclosure are shown for the temperature of another exemplary resistance heater.

[0014] Figure 8A An exemplary power curve based on the temperature of another exemplary resistance heater according to an embodiment of the present disclosure is shown;

[0015] Figure 8B An exemplary test circuit for measuring the electrical characteristics of a PPTC device is depicted.

[0016] Figure 9The power curve is shown based on the temperature of a reference exemplary heater;

[0017] Figure 10A A side view of an exemplary PPTC resistance heater 350 according to an embodiment of the present disclosure is depicted;

[0018] Figure 10B and Figure 10C The plan depicts Figure 10A Alternative variants of the resistance heater assembly;

[0019] Figure 11 An exemplary circuit diagram of a PPTC-based resistance heater is provided;

[0020] Figure 12 An exemplary PPTC-based resistance heater assembly according to embodiments of the present disclosure is depicted;

[0021] Figure 13 An exemplary circuit diagram of a PPTC-based resistance heater is provided;

[0022] Figure 14 An exemplary PPTC resistance heater according to an embodiment of the present disclosure is depicted;

[0023] Figure 15A A cross-section of a novel camera according to an embodiment of the present disclosure is depicted; and

[0024] Figure 15B Plan view and perspective view of the components of a heater according to an embodiment of the present disclosure are depicted. Detailed Implementation

[0025] This embodiment will now be described more fully below with reference to the accompanying drawings, in which exemplary embodiments are illustrated. The embodiments should not be construed as limited to those set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. In the drawings, similar numerals always refer to similar elements.

[0026] In the following description and / or claims, the terms “on,” “overlaying,” “disposed on,” and “over” are used. “On,” “overlaying,” “disposed on,” and “over” can be used to indicate that two or more elements are in direct physical contact with each other. Furthermore, the terms “on,” “overlaying,” “disposed on,” and “over” can mean that two or more elements are not in direct contact with each other. For example, “over” can mean that one element is on top of another element without contacting each other, and there may be one or more other elements between the two elements. Additionally, the terms “and / or” can mean “and,” can mean “or,” can mean “exclusive-or,” can mean “one,” can mean “some, but not all,” can mean “neither,” and / or can mean “both,” although the scope of the claimed subject matter is not limited in this respect.

[0027] In various embodiments, a novel PPTC material is provided, comprising a conductive filler having nanoscale carbon filler material, such as single-walled carbon nanotubes, multi-walled carbon nanotubes, or graphene. The PPTC material may include a polymer matrix, such as polyethylene, polyethylene copolymers, polyesters, polyurethanes, polyamides, fluoropolymer resins, or mixtures of fluoropolymers and other polymers. In various non-limiting embodiments, the PPTC material may include antioxidants, dispersants, crosslinking agents, arc-suppressing agents, etc. As detailed below, the PPTC material of this embodiment offers the advantage of stable power over a temperature range from room temperature to the maximum operating temperature, wherein the power variation may be less than 60%, for example 50%-60%, or in some embodiments, less than 30%, for example 20%-30%.

[0028] Specific embodiments are based on polymeric positive temperature coefficient (PPTC) materials formed from graphene fillers and a semi-crystalline polymer matrix. The stable resistive properties imparted by this PPTC material offer new applications, such as resistance heaters employing PPTC components. The stable resistive properties based on temperatures below the melting point of the polymer matrix result in stable heater power characteristics based on temperatures below the melting point of the polymer matrix, which is typically associated with the trip temperature of the PPTC component. Another advantage is uniform and efficient heat transfer. Furthermore, since resistivity and trip temperature can be customized by tailoring the type of polymer, the conductive filler, and the volume fraction of the conductive filler, power consumption and power limiting temperatures can be customized according to the application of the resistance heater.

[0029] In certain embodiments, the PPTC material can be configured as a polymer matrix having a shape and size defining the PPTC body, depending on the desired application. As an example, the PPTC heater can be configured as a planar heater, including a ring heater or other suitable shapes. The PPTC material may also include a graphene filler component disposed within the polymer matrix, wherein the graphene filler component is formed from a plurality of graphene sheets arranged along a predetermined plane of the PPTC body (e.g., the main plane of a ring-shaped PPTC assembly).

[0030] While in some embodiments the PPTC material may include a conductive filler formed solely of graphene filler, in other embodiments a second conductive filler, such as a known carbon filler, may be added in addition to the graphene filler. Figure 1 A PPTC assembly according to an embodiment of the present disclosure is shown. The PPTC assembly 100 includes a PPTC body 102, which in turn includes a polymer matrix 104 and a graphene filler 106, the graphene filler 106 being dispersed as microsheets within the polymer matrix 104. The PPTC assembly 100 also includes a pair of opposing electrodes, shown as electrodes 108, wherein an external voltage can be applied to drive current through the PPTC body 104 between the opposing electrodes. Non-limiting examples of suitable polymers for the polymer matrix 104 include semi-crystalline polymers such as polyethylene, polyester, polyvinylidene fluoride, ethylene tetrafluoroethylene, ethylene-vinyl acetate, ethylene-acrylic acid copolymer, ethylene-butyl acrylate copolymer, and perfluoroalkoxy.

[0031] In some embodiments, the volume percentage of the polymer matrix in the PPTC body 102 can be between 50% and 99%, and in specific embodiments, the volume percentage of the polymer matrix can be between 60% and 95%. In various non-limiting embodiments, the volume fraction of graphene can be between 1% and 50%, and in specific embodiments, it can be between 4% and 30%. The graphene used for the graphene filler 106 can be prepared by mechanical or chemical methods, wherein the graphene particles are formed from graphene sheets, and according to various embodiments, the number of graphene sheets in a particle ranges from one to several hundred layers, and in specific embodiments, from one to approximately 30 layers. Thus, graphene particles formed from multiple graphene sheets can also have a two-dimensional sheet-like shape. According to some embodiments, the resulting graphene particle size can be between 0.1 μm and 100 μm, particularly between 1 μm and 30 μm.

[0032] As background, graphene is a two-dimensional carbon crystalline allotrope. In graphene, carbon atoms are densely arranged in a regular, atomic-scale hexagonal pattern. Graphene has a wavelength of 1500-2500 W·m. -1 .K - High thermal conductivity within a certain range. Figure 1In this embodiment, the graphene filler is configured as sheet-like particles, wherein the particles (meaning the planes of these sheets) are typically aligned along a predetermined plane of the PPTC body 104 (e.g., along the XY plane of the illustrated Cartesian coordinate system). The high thermal conductivity of the graphene filler 106 allows for efficient heat transfer to the environment along the Z-direction, as well as uniform heat transfer in the XY plane. These thermal properties are particularly useful for heater applications. Furthermore, the bulk resistivity of the graphene sheets is as low as 10⁻⁶. -6 Ω-cm, the bulk resistivity of most conductive metals is close to 2×10⁻⁶. -6 Ω-cm or higher. Furthermore, the 2D structure of graphene allows the semi-crystalline polymer in the polymer matrix 104 to contact both sides of the graphene particles, enabling the PPTC material to respond to temperature synchronously when the polymer matrix 104 reaches its melting point.

[0033] Figure 2 Another PPTC component 120 according to an embodiment of the present disclosure is shown. In this example, PPTC component 120 may be configured substantially the same as PPTC component 100 described above, wherein similar components are labeled as identical. The difference between PPTC component 120 and PPTC component 100 is that the PPTC body 112 further includes a conductive component 110, which may be a carbon filler and / or a ceramic conductive component, configured as a plurality of carbon particles or ceramic conductive particles (e.g., TiC or WC) within the polymer matrix 106. Thus, the conductive component 110 can modify the electrical properties of PPTC component 120 relative to the electrical properties of PPTC component 100.

[0034] Figure 3 The resistance at temperature is shown according to an embodiment of the present disclosure for an exemplary PPTC material. In this case, two different curves represent two different PPTC materials (generally as shown in the figure). Figure 1 and Figure 2 The characteristics are as shown in the diagram. The lower curve corresponds to PPTC component 100, while the upper curve corresponds to PPTC component 120. In both examples, the resistance is relatively low and stable from room temperature to approximately 140°C-150°C, while it increases rapidly at a trip temperature of 170°C. For pure graphene components, the resistance increases to 900 ohms or more, while for PPTC components with graphene and carbon fillers, the resistance increases to 24,000 ohms or more. Notably, in both examples, the low-temperature resistance below the trip temperature is very stable.

[0035] Figure 4A schematic diagram of the processing of a PPTC assembly according to an embodiment of the present disclosure is shown. To form a suitable PPTC assembly, such as for heater applications, PPTC material can be extruded in an extrusion apparatus to form PPTC layers or sheets. Generally, PPTC material 220 (e.g., a mixture of polymer material and graphene particles) can be added to a container 202 coupled to an extrusion chamber 204, wherein the PPTC material 220 can be mixed, heated, and stretched by an extrusion assembly 206 to form a PPTC body 210 in sheet or layer form.

[0036] Figure 5 An exemplary processing flow 302 is depicted. At box 302, a polymeric material, conductive powder, and optional additives are mixed together. The polymeric material may be a powder of a semi-crystalline polymer, while the conductive filler includes graphene particles and may optionally include carbon and / or conductive ceramic particles. At box 304, a hot-melt process is performed, wherein the mixed components, such as the polymer and conductive filler, are heated to a temperature to melt the polymer and accordingly disperse the conductive filler particles more uniformly within the polymer matrix. At box 306, sheet extrusion is performed to form a sheet of PPTC material, wherein the molten mixture of polymer and conductive filler is extruded to form a PPTC sheet or layer. At box 308, a conductive metal layer (foil) may be applied to the top and bottom surfaces of the extruded PPTC sheet to form a laminated body. At box 310, a PPTC assembly or multiple PPTC assemblies, including a PPTC body sandwiched between opposing electrodes, are formed by unifying the laminated body to form a single component. In some examples, the uniform PPTC body can have a ring shape (e.g., a circular ring, rectangular ring, oval ring, elliptical ring, or polygonal ring). At box 312, the uniform PPTC body is assembled into a device such as a heater. For example, the uniform PPTC body can be attached to leads (wires) connected to opposing electrodes to form a PPTC heater. Optionally, the heater can be incorporated into another structure, such as a camera or other structure to be heated. At box 314, an insulating coating can be applied to encapsulate the components of the PPTC heater. For example, the insulating coating can be formed by electrophoretic deposition in a chemical bath; by forming a palylene coating via CVD; or by forming other insulating coatings.

[0037] Now go to Figure 6A and Figure 6B According to embodiments of this disclosure, exemplary resistance and power curves based on the temperature of an exemplary resistance heater are shown. The exemplary heater is formed of a PPTC material having graphene filler and a polymer matrix. Figure 6AAs shown, the resistance varies little between 25°C and approximately 150°C, then increases sharply above 170°C. Conversely, below 100°C, the power dissipation remains between 3.3 watts and 3 watts, gradually decreasing to 1.8 W at 150°C, and decreasing sharply above 150°C, decreasing to approximately 0.2 watts at 175°C, thus limiting the power near the melting point of the polymer.

[0038] Figure 7A and Figure 7B Exemplary resistance and power curves according to embodiments of the present disclosure are shown at temperatures relative to another exemplary resistance heater. The exemplary heater is formed of a PPTC material having graphene filler, carbon filler, and a polymer matrix. Figure 7A As shown, the resistance varies little between 25°C and approximately 150°C, then increases sharply above 170°C. Conversely, below 100°C, the power consumption decreases from 3.3 watts to approximately 2.6 watts, then decreases more rapidly, approaching zero watts at 170°C. These results demonstrate how heater characteristics can be tuned by adding carbon to a graphene-based PPTC matrix.

[0039] In other embodiments of this disclosure, the PPTC heater may be formed of a PPTC material having a filler formed of a carbon nanotube material (e.g., a single-walled or multi-walled carbon nanotube material). Figure 7C and Figure 7D Exemplary resistance and power curves according to embodiments of the present disclosure are shown at temperatures relative to another exemplary resistance heater. The exemplary heater is formed of a PPTC material having carbon nanotube filler and a polymer matrix. Figure 7D As shown, below 150°C, the power level is relatively more stable than that of PTC heaters based on carbon fillers, as described below. Figure 9 The subject of discussion.

[0040] Figure 8A An exemplary power curve of the temperature of another exemplary resistance heater according to an embodiment of the present disclosure is shown. Figure 8B An exemplary test circuit for measuring the electrical characteristics of PPTC devices is depicted. Figure 8AThe diagram shows two power curves: one with 16 V applied to the heater and the other with 13.5 V applied. Higher voltage results in higher drive power (compare 3.4 watts vs. 2.4 watts). However, for both cases, the power remains almost constant between 20°C and 140°C, then drops rapidly above 150°C, reaching a power level below 1 watt above 170°C. This power drop above 150°C reflects the tripping of the PPTC heater, where the resistance increases rapidly, thus limiting the current and total power for a given applied voltage. Therefore, Figure 8A The heater element made of PPTC material functions over a wide temperature range to provide uniform power before the power drops below the limit power above the trip temperature.

[0041] In comparison, Figure 9 The power curves are shown based on the temperature of a reference heater using PPTC without graphene filler. Figure 9 The diagram also shows two power curves: one with 16 V applied to the heater and the other with 13.5 V applied. Higher voltage results in higher drive power (compare 2.1 watts to 1.5 watts). However, in both cases, the power drops significantly between 20°C and 140°C, reaching essentially zero watts above 150°C. Therefore, this resistance heater does not exhibit stable power output over a useful temperature range (e.g., below the trip temperature, between room temperature and 150°C).

[0042] According to various embodiments of this disclosure, PPTC heaters can be adapted for use in components, such as cameras. (See below for more details.) Figure 10A-1 In embodiment 5, a novel configuration of the PPTC resistance heater is illustrated, including incorporating the PPTC resistance heater into a camera. According to various embodiments, the PPTC resistance heater may be based on a known PPTC material, such as a carbon-filled polymer, or may be based on a graphene-filled polymer, generally as described in the foregoing embodiments. PPTC heaters based on graphene-filled polymers are particularly suitable for applications requiring stable current operation over an extended temperature range.

[0043] Figure 10A A side view of an exemplary PPTC resistance heater 350 according to an embodiment of the present disclosure is depicted. The resistance heater 350 includes a PPTC resistance heater assembly 360 and an external lead 370. For example, the resistance heater assembly may be generally as described above regarding... Figure 1-2The embodiment is configured as described. When viewed in a plan view, the resistance heater assembly 360 may have a ring shape to surround the periphery of the component to be heated (e.g., a camera). The arrows depict the current path from the left conductor 370 through the PPTC resistance heater assembly 360 and out of the right conductor 370. Figure 10B and Figure 10C An alternative variant of the resistance heater assembly 360 is depicted in the plan view. The resistance heater assembly 360 includes a PPTC body 362 configured as an annular shape, and a counter electrode, shown as electrode 364. Figure 10B As shown, for example, the resistance heater assembly 360A is provided with opposite electrodes as two annular segments (shown as segments 364A and 364B), wherein, as shown, a portion of the annulus is exposed in exposed areas 362A and 362B. Figure 10A and Figure 10B The configurations differ from each other in the following aspects: the relative positions of segments 364A and 364B, and the shape and size of exposed areas 362A and 362B. Due to this configuration, such as Figure 10A As shown, the current flowing through the path of least resistance can flow vertically from the left conductor 370 to the lower part of the electrode 364, and then flow laterally along the lower surface of the PPTC body along the electrode 364. Then, the discontinuity in the electrode 364 can cause the current to flow vertically to the upper surface, and then flow laterally along the upper surface, from the upper surface to the lower surface of the PPTC body, flow laterally along the lower electrode, and flow vertically out of the right conductor 370.

[0044] Figure 11 A circuit diagram of an exemplary PPTC-based resistance heater is provided in Figure 10. Components R0 and R7 represent resistances from wire 370. Components R1, R4, and R6 represent resistances from the foil, while components R2, R3, and R5 represent resistances from the PTC ring. As shown, the resistance of component R3 can be greater than the resistances of R2 and R5 generated on the left and right sides of the PTC ring.

[0045] Figure 12 An exemplary PPTC-based resistance heater assembly according to an embodiment of the present disclosure is depicted, shown as PPTC heater assembly 400. In this example, PPTC heater assembly 400 has a planar ring shape, as shown in the side view (top and bottom) and plan view (middle). PPTC heater assembly 400 can be generally as follows... Figure 1-2 The embodiment is configured as shown, wherein the PPTC body is sandwiched between opposing electrodes. In this case, the opposing electrodes can cover most of the upper and lower ring surfaces.

[0046] Figure 13 Provided Figure 12An exemplary circuit diagram of a PPTC-based resistance heater is provided. Components R0 and R7 represent resistances from external wires to be connected to the PPTC heater 400. Components R1, R2, R5, and R6 represent resistances from the pads, while components R3 and R4 represent resistances from the PTC body.

[0047] Figure 14 A side view of an exemplary PPTC resistance heater 450 according to an embodiment of the present disclosure is depicted. The resistance heater 450 includes a PPTC resistance heater assembly 400 and an external lead wire 410. Arrows depict current paths from the left lead wire 410 through the PPTC resistance heater assembly 400 and out of the right lead wire 410. As shown, current can flow from the left lead wire 410, vertically from the lower surface of the PPTC body to the upper surface, then laterally along the upper electrode, vertically from the upper surface to the lower surface of the PPTC body, laterally along the lower electrode, and then out of the right lead wire 410.

[0048] In various embodiments, the PPTC heater may be incorporated into a printed circuit board (PCB). For example, the resistance heater assembly 400 may be incorporated into a resistance heater using a PCB to support a surface-mount PTC resistance heater configuration.

[0049] As indicated, the PPTC resistance heater according to this embodiment can be incorporated into the camera. Figure 15A A novel camera 500 is described, comprising a PPTC resistance heater assembly 400A configured as a ring to be incorporated into a camera lens assembly. The PPTC resistance heater assembly 400A can be in thermal contact with a camera lens 430 to heat the lens via resistance heating. Due to its ring shape, the outer periphery of the camera lens 430 can be directly heated. In this way, for example, the camera lens can be heated to a given amount to expel moisture or precipitation.

[0050] exist Figure 15A In a particular embodiment, heater assembly 400A can conduct current as shown with respect to heater assembly 400 discussed above. Heater assembly 400A includes a PTC body 412, a metal foil layer 414, a conductive metal portion 418, and an insulating layer 416. Heater assembly 400A can be connected to wire 410 via contact metal 419. Figure 15B The diagram shows a plan view of heater assembly 400A, in which... Figure 15A The top corresponds to along Figure 15BThe cross-section of the semicircular path AA is shown. Therefore, the heater assembly 400A can be configured according to surface mount technology. Specifically, the heater assembly 400A can be supported on the PCB ring 420, wherein the heater assembly 400A and the PCB ring 420 have annular shapes, as shown... Figure 15B As shown. The heater assembly 400A can be divided into two sections as shown, in order to produce approximately as... Figure 14 The current path is shown. It is noteworthy that the current between the conductors 410 can travel along two semi-circular parallel paths. In various non-limiting embodiments, the total thickness of the heater assembly 400A can be approximately 2 mm, while the thickness of the PCB ring 420 is less than 1.5 mm. Non-limiting examples of suitable materials for the PCB ring 420 include FR4, copper-inlay PCBs, or ceramic (e.g., Al2O3 or AlN) PCBs.

[0051] When the PPTC resistance heater according to this embodiment is incorporated into a camera or other device to be heated, the following advantages are achieved: 1) self-balancing power distribution design; 2) a thin but fully insulated assembly from the camera housing; 3) a heater with a special shape that can be adapted to very narrow areas; 4) an assembly in which the power vs. temperature performance of the resistance heater can be adjusted by adjusting the filler formulation (e.g., the volume fraction of graphene particles (for graphene-based PPTC materials) and optional carbon particles added to the polymer matrix); 5) a resistance heater that has stable power generation vs. temperature operation (for graphene-based PPTC materials) over a wide temperature range to achieve the maximum operating temperature; 6) higher power generation in colder environments; 7) lower power generation in hotter environments; and 8) a resistance heater with self-limiting power.

[0052] While this embodiment has been disclosed with reference to certain embodiments, many modifications, alterations, and changes are possible to the described embodiments without departing from the scope and breadth of this disclosure, as defined in the appended claims. Therefore, this embodiment is not limited to the described embodiment and may have the full scope defined by the language of the following claims and their equivalents.

Claims

1. A resistance heater, comprising: Polymer positive temperature coefficient (PPTC) material, which is configured as an annulus defining the heater body; as well as An electrode assembly comprising two or more electrodes, each configured to contact the heater body at regions spaced two or more circumferentially apart. PPTC materials include: A polymer matrix defining a PPTC body; and A conductive filler component disposed in the polymer matrix allows current to flow vertically through the PPTC body between the two or more electrodes and laterally along the two or more electrodes at spaced contact areas to generate self-limiting heating characteristics.

2. The resistance heater according to claim 1, wherein the annulus includes a circular annulus, a rectangular annulus, an elliptical annulus, an oval annulus, or a polygonal annulus.

3. The resistance heater according to claim 1, wherein the conductive filler component comprises carbon filler and / or conductive ceramic component, which are disposed in the polymer matrix as a plurality of carbon particles.

4. The resistance heater according to claim 1, wherein, The volume percentage of the polymer matrix is ​​between 50% and 99%.

5. The resistance heater according to claim 1, wherein the conductive filler comprises a graphene filler component and / or a carbon nanotube filler component.

6. The resistance heater of claim 1 further includes a first lead and a second lead electrically connected to the electrode assembly, the first lead and the second lead extending perpendicular to the plane of the heater body.

7. The resistance heater according to claim 1, wherein, The two or more electrodes include a top electrode and a bottom electrode, wherein the top electrode and the bottom electrode are arranged in a ring.

8. The resistance heater according to claim 7, wherein, The top electrode and the bottom electrode each include two segments separated by a first gap and a second gap, wherein the first gap and the second gap correspond to a first exposed area and a second exposed area of ​​the heater body.

9. The resistance heater according to claim 1, wherein, The heater body is mounted on a printed circuit board (PCB) substrate, which is arranged in a ring shape.

10. The resistance heater of claim 9, wherein the heater body and the electrode assembly together comprise a thickness in the range of 2 mm, and the PCB substrate comprises a thickness of less than 1 mm.

11. The resistance heater according to claim 9, wherein the PCB substrate comprises FR4, embedded copper PCB, or ceramic PCB.

12. A camera, comprising: Transparent lens section; as well as A resistance heater, disposed on the periphery of the transparent lens portion, includes: A polymeric positive temperature coefficient (PPTC) material, which is arranged in a plane as a ring and defines a heater body, wherein the PPTC material comprises: A polymer matrix defining a PPTC body, and The conductive filler component disposed in the polymer matrix; and An electrode assembly includes a bottom electrode on a first side of the heater body and a top electrode disposed on a second side of the heater body opposite to the first side, wherein the top electrode and the bottom electrode each include two segments separated by a first gap and a second gap, wherein the first gap and the second gap correspond to a first exposed area and a second exposed area of ​​the heater body.

13. The camera according to claim 12, wherein the ring includes a circular ring, a rectangular ring, an elliptical ring, an oval ring, or a polygonal ring.

14. The camera according to claim 12, wherein the filler component comprises a carbon filler component disposed within the polymer matrix as a plurality of carbon particles.

15. The camera of claim 12, further comprising: A first lead and a second lead are electrically connected to the electrode assembly, the first lead and the second lead extending perpendicular to the plane of the heater body.

16. The camera according to claim 12, wherein the conductive filler comprises a graphene filler component and / or a carbon nanotube filler component.

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