Circuit protection device

Abstract

The present application provides a circuit protection device, comprising: a patch type thermistor element including a first electrode and a second electrode; a first heat dissipation terminal connected with the first electrode; a second heat dissipation terminal connected with the second electrode; and a housing protecting the thermistor element, the first heat dissipation terminal and the second heat dissipation terminal. The circuit protection device according to the present application having an SMD (Surface Mount Device) structure can be applied to an ultra-thin wall-mounted television.

Description

Technical Field

[0001] This application relates to a circuit protection device, and more specifically, to a circuit protection device that limits inrush current during the initial operation of electronic equipment and prevents fire caused by internal temperature rise or overcurrent. Background Technology

[0002] Typically, large electronic appliances such as televisions, air conditioners, washing machines, refrigerators, and dryers are equipped with circuit protection devices at their power input terminals to prevent equipment malfunctions caused by excessively large pulse values ​​such as surge current and surge voltage when power is applied.

[0003] Inrush current refers to the temporary high pulse current that occurs in the circuit of an electronic device when it is powered on. Excessive inrush current may exceed the current limits of semiconductor devices such as diodes used in the power supply, and the resulting voltage spikes may damage these semiconductor devices.

[0004] Figure 1 This is a circuit diagram of a prior art circuit protection device. The conventional circuit protection device includes a resistor R, a first relay S1 connected in series with the resistor R, and a second relay S2 connected in parallel with the resistor R and the first relay S1.

[0005] When the circuit protection device is energized, the first relay S1 closes and the second relay S2 opens, entering state (a). After a predetermined time, the first relay S1 opens and the second relay S2 closes, switching to state (b).

[0006] exist Figure 1 In state (a), the input current flows into the circuit through the first relay S1 and the resistor R. At this time, the resistor R limits the surge current to a predetermined level, thereby suppressing the surge current. After a predetermined time (e.g., about 0.5 seconds) when the input current stabilizes, the circuit protection device switches to state (b), and then the normal input current flows into the circuit through the second relay S2.

[0007] Traditional circuit protection devices of this type include a resistor R and relatively large first and second relays S1 and S2, resulting in high cost, large installation space requirements, and frequent failures. The normal input current of a washing machine may be between 2A and 4A, while the normal input current of a dryer may reach 7A or higher. Therefore, the first and second relays S1 and S2 need to be high-current relays. However, such high-current relays are expensive and have limited supply in South Korea; most high-current relays need to be imported from countries such as Japan.

[0008] Furthermore, because the first relay S1 and the second relay S2 are repeatedly switched on and off each time the electronic device is powered on and off, the durability of the relays will decrease over time, leading to failure. Failure of the first relay S1 and the second relay S2 may result in excessive current flowing into the circuit, potentially even causing a fire. Therefore, circuit protection devices using relays inherently carry this type of risk.

[0009] To address these issues, circuit protection devices using NTC thermistors (negative temperature coefficient thermistors) to reduce surge current have been adopted. A thermistor is a device that utilizes the characteristic that the resistance of a semiconductor changes with temperature. Among thermistors, NTC thermistors exhibit the characteristic that their resistance decreases as the temperature increases. An NTC thermistor element may include a disk-shaped body, a pair of electrodes formed on the surface of the body, and a pair of leads soldered to and extending outward from the electrodes.

[0010] In related prior art, for example, Korean Patent No. 10-1189853 discloses a ceramic heat dissipation element that improves heat dissipation characteristics by placing an NTC thermistor element inside a ceramic housing and filling the housing with cement-based filler.

[0011] Traditional ceramic heat sinks have shown no significant problems when used in household appliances such as 40-inch televisions with power consumption below 200W. For appliances with power consumption of approximately 200W, two to four traditional ceramic heat sinks can be used in series. For example, in a television or similar appliance, if four ceramic heat sinks are connected in series to control a circuit protection device with a total resistance of approximately 5 ohms, then the resistance of each ceramic heat sink is approximately 1.3 ohms. Compared to a single 5-ohm ceramic heat sink, four 1.3-ohm ceramic heat sinks generate less heat (according to Joule's law P=I²R), thus resulting in better heat dissipation management.

[0012] However, when applying existing ceramic heat sinks to large household appliances with power consumption exceeding 200W, such as recently commercialized 65-inch and larger televisions, it is necessary to connect five or more ceramic heat sinks with a resistance of less than 1.3 ohms in series to achieve heat dissipation management. Manufacturing NTC thermistors with a resistance of less than 1.3 ohms is technically challenging, and even if successfully manufactured, such thermistors may not exhibit the inherent characteristics of NTC thermistors.

[0013] Therefore, for household appliances with power consumption exceeding 200W, such as televisions larger than 65 inches, the aforementioned method of connecting ceramic heat dissipation components in series cannot be simply used; to cope with the heat generated by the high current, it is necessary to adopt... Figure 1 The conventional first relay S1 and second relay S2 circuit is shown, and a single ceramic heat sink element with a predetermined resistance value (e.g., 5 ohms) is used as a resistor R.

[0014] However, using the first relay S1, the second relay S2, and the ceramic heat sink simultaneously not only results in high cost and large space occupation, but also presents mechanical failure and durability issues with the first relay S1 and the second relay S2. Therefore, an improved circuit protection device is urgently needed.

[0015] The current trend in television development is towards larger screen sizes and thinner screens. With advancements in display technology, ultra-thin televisions are also becoming increasingly thinner. However, the circuit boards and components within the television can hinder the achievement of ultra-thin designs. In particular, existing circuit protection devices, due to their considerable thickness, present challenges in achieving ultra-thin designs for wall-mounted televisions. Summary of the Invention

[0016] To address the shortcomings of existing technologies, this invention proposes a circuit protection device, the technical solution of which is as follows: This application provides a circuit protection device with an SMD (Surface Mounted Devices) structure, the thickness of which is suitable for use in ultra-thin wall-mounted TVs.

[0017] This application also provides a circuit protection device that still has an effective heat dissipation structure even at ultra-thin thickness.

[0018] The purpose of this application is not limited to the above-mentioned contents. Other purposes not mentioned can be clearly understood by those skilled in the art from the following description.

[0019] In one aspect of this application, a circuit protection device is provided, comprising: a surface-mount thermistor element including a first electrode and a second electrode; a first heat dissipation terminal connected to the first electrode; a second heat dissipation terminal connected to the second electrode; and a housing for protecting the thermistor element, the first heat dissipation terminal, and the second heat dissipation terminal.

[0020] In addition, the thermistor element may include a rectangular or circular ceramic plate, and a first electrode and a second electrode respectively printed on opposite surfaces of the ceramic plate.

[0021] In addition, the first electrode can be disposed on the upper surface of the ceramic plate, and the second electrode can be disposed on the lower surface of the ceramic plate.

[0022] In addition, one end of the first heat dissipation terminal can form an electrical surface contact with the first electrode, and one end of the second heat dissipation plate terminal can form an electrical surface contact with the second electrode.

[0023] In addition, the other end of the first heat sink terminal and the second heat sink terminal can form an electrical surface contact with the corresponding terminal on the printed circuit board (PCB).

[0024] Furthermore, the first heat dissipation terminal can be made to have its other end at the same height as the other end of the second heat dissipation terminal by a first bend and a second bend formed between its one end and the other end, and to form an electrical surface contact with the terminal on the PCB.

[0025] In addition, the first heat dissipation terminal and the second heat dissipation terminal can be configured to dissipate the heat generated by the thermistor element to the PCB through conduction.

[0026] Specific details of other embodiments are included in the "Detailed Description" and the accompanying drawings.

[0027] The advantages and / or features of this application and their implementation methods will be clearly presented in conjunction with the accompanying drawings and through the various embodiments described in detail below.

[0028] However, this application is not limited to the structures of the embodiments disclosed below, and can be implemented in many other forms. The embodiments disclosed herein are only used to ensure the completeness of this application and to fully communicate the scope of this application to those skilled in the art. This application is defined only by the claims. Attached Figure Description

[0029] Figure 1 This is a circuit diagram of a circuit protection device in the relevant prior art.

[0030] Figure 2 This is an example diagram of a circuit protection device according to an embodiment of this application.

[0031] Figure 3 for Figure 2 An example diagram of the upper surface of the circuit protection device in the disassembled state of the housing.

[0032] Figure 4 for Figure 2 The diagram shows an example of the lower surface of the circuit protection device in the disassembled state of the housing.

[0033] Figure 5 for Figure 2 The diagram shows a cross-sectional view of the circuit protection device.

[0034] Reference numerals: 100, circuit protection device; 110, housing; 121, first heat dissipation terminal; 122, second heat dissipation terminal; 123, attachment reinforcement hole; 124, attachment reinforcement part; 125, attachment reinforcement part; 126, first bending part; 127, second bending part; 130, thermistor element; 141, first electrode; 142, second electrode; 143, exposed part; 144, exposed part. Detailed Implementation

[0035] Before describing this application in detail, it should be understood that the terms or expressions used in this specification should not be interpreted solely according to their conventional or dictionary meanings. The inventors may appropriately define the terms in accordance with the best interpretation of the invention, and therefore these terms should be interpreted as having meanings consistent with the technical spirit of this application.

[0036] The terminology used herein is for describing preferred embodiments of the invention only and is not intended to limit its scope. The definitions of these terms take into account various possible embodiments of the invention.

[0037] Furthermore, unless explicitly stated otherwise, the singular form used in this article carries a plural meaning, and vice versa. Therefore, depending on the context, even when expressed in the singular form, its meaning may include the plural.

[0038] Throughout this specification, expressions such as “comprising” or “including” should be understood to mean that other elements may be included, unless the opposite is explicitly stated.

[0039] Furthermore, when describing a component as "mounted," "connected to," or "located" within another component, both direct and indirect connections / mounting are included. That is, the component may be mounted in direct contact with another component or mounted at a distance. If it is mounted at a distance, there may be a third component or device for securing or connecting them; the description of this third component or device may be omitted unless necessary.

[0040] On the other hand, expressions such as "directly connected" or "directly adjacent" indicate that there are no other elements or devices between the described elements.

[0041] Similarly, other relational expressions such as "between" and "directly between", "adjacent" and "directly adjacent", should also be interpreted in the same way.

[0042] Terms such as “one surface,” “another surface,” “one side,” “the other side,” “first,” and “second” are used only to clearly distinguish elements and do not limit the nature or order of elements unless explicitly stated.

[0043] Terms such as “up,” “down,” “left,” and “right,” which indicate direction or position, are used to describe the relative positions shown in the accompanying drawings. They should be understood as indicating the relative positions of the elements in the drawings. Unless explicitly stated otherwise, absolute positions are not defined.

[0044] In this specification, even if elements appear in different figures, the same reference numerals are used to indicate the same or equivalent elements. Therefore, throughout the specification, the same reference numerals always indicate the same or equivalent elements.

[0045] In the accompanying drawings, in order to fully and clearly convey the main idea of ​​this application or for ease of explanation, the dimensions, positions, connections, etc. of the various elements constituting this application may be enlarged, reduced, or omitted. Therefore, the scale or dimensions may not be strictly accurate.

[0046] Furthermore, in the following description of this application, detailed descriptions of structures that are deemed potentially obscuring the main points of this application (e.g., known technologies that include related prior art) may be omitted.

[0047] The embodiments of this application will now be described in detail with reference to the accompanying drawings. For convenience, in the drawings, the X-axis, Y-axis, and Z-axis are defined as the left-right direction, the front-back direction, and the up-down direction, respectively.

[0048] Reference Figures 2 to 5 One embodiment of the circuit protection device 100 of this application may include a circuit protection element and a housing 110. The circuit protection element includes a thermistor element 130, a first heat dissipation terminal 121, and a second heat dissipation terminal 122.

[0049] Thermistor element 130 is a semiconductor resistor whose resistance changes significantly with temperature. Thermistor element 130 may include an NTC (negative temperature coefficient) thermistor or a PTC (positive temperature coefficient) thermistor. The resistance of an NTC thermistor decreases with increasing temperature; conversely, the resistance of a PTC thermistor increases with increasing temperature.

[0050] The manufacturing process of the thermistor element 130 (e.g., NTC thermistor) is as follows: a square ceramic plate is made from various transition metal oxides such as manganese and nickel, silver (Ag) paste is applied to both surfaces of the square ceramic plate, and then the first electrode 141 and the second electrode 142 are formed by baking, thereby forming a heating element.

[0051] The housing 110 can be made of a plastic with excellent thermal insulation properties. The housing 110 can be made of thermosetting plastics such as melamine resin, epoxy resin, or phenolic resin. Thermosetting plastics have high hardness and excellent heat resistance, and therefore can be used as the material for the housing 110 in the embodiments of this application.

[0052] This application discloses an embodiment of a circuit protection device 100 that can be mounted on a PCB using SMT (Surface Mount Technology). That is, the circuit protection device 100 corresponds to an SMD (Surface Mount Device) mounted on the surface of the PCB.

[0053] SMT is a surface mount technology. DIP (Dual In-line Package) uses component leads that pass through holes in the PCB and are soldered to the other side. Unlike DIP packages, SMD packages are directly mounted on the PCB surface and secured by soldering. Therefore, the surface mount circuit protection device 100 is horizontally mounted on the PCB, requiring no leads, and connects directly to terminals on the PCB via heat dissipation terminals, thus enabling a structure with a thickness of less than 3mm.

[0054] According to existing technologies, a thermistor may include a ceramic disk, positive and negative electrodes attached to the ceramic disk, connecting leads respectively connected to the positive and negative electrodes, and a coating covering the ceramic disk and the positive and negative electrodes. In existing technologies, the ceramic disk may be vertically arranged, and the connecting leads may serve as pins supporting the ceramic disk and enabling PCB mounting. Existing thermistors do not have a dedicated heat dissipation structure, relying solely on convection or radiation for heat dissipation.

[0055] One embodiment of this application shows that the thermistor element 130 has an ultra-thin structure and includes a dedicated heat dissipation structure. The circuit protection device 100 may include a first heat dissipation terminal 121 and a second heat dissipation terminal 122 that respectively form electrical contacts with the first electrode 141 and the second electrode 142 of the thermistor element 130.

[0056] The first heat dissipation terminal 121 and the second heat dissipation terminal 122 are used to electrically connect the thermistor element 130 to the PCB and dissipate the heat generated by the thermistor element 130.

[0057] The thermistor element 130 may include a rectangular or circular ceramic plate, and a first electrode 141 and a second electrode 142 respectively printed on opposite surfaces of the ceramic plate. For example, the first electrode 141 and the second electrode 142 may be formed by printing a thin film of silver paste (Ag paste) on opposite surfaces of the ceramic plate. Therefore, the first electrode 141 and the second electrode 142 do not increase the thickness of the ceramic plate.

[0058] The first electrode 141 can be printed on the upper surface of a horizontally arranged ceramic plate, and the second electrode 142 can be printed on the lower surface of the horizontally arranged ceramic plate. The first electrode 141 can occupy more than 50% of the area of ​​the upper surface of the ceramic plate, and the second electrode 142 can occupy more than 50% of the area of ​​the lower surface of the ceramic plate.

[0059] The first heat dissipation terminal 121 and the second heat dissipation terminal 122 can be made of aluminum alloy or copper to achieve high conductivity and excellent heat dissipation performance. The first heat dissipation terminal 121 can form electrical contact with the first electrode 141, and the second heat dissipation terminal 122 can form electrical contact with the second electrode 142. For example, the first heat dissipation terminal 121 can be fixed by welding while in contact with the first electrode 141; the second heat dissipation terminal 122 can be fixed by welding while in contact with the second electrode 142. In this case, the fixing method is not limited to welding, and methods such as conductive adhesive can also be used.

[0060] To facilitate soldering, the first heat dissipation terminal 121 and the second heat dissipation terminal 122 may only contact a portion of the first electrode 141 or the second electrode 142. For example, the first electrode 141 may have an exposed portion 143, and the second electrode 142 may also have an exposed portion 144. With the help of the exposed portions 143 and 144 of the first electrode 141 and the second electrode 142, soldering can be performed without affecting the ceramic plate.

[0061] The first heat dissipation terminal 121 and the second heat dissipation terminal 122 may be provided with attachment reinforcement holes 123 and attachment reinforcement parts 124 and 125 respectively, so as to improve the bonding strength with the first electrode 141 and the second electrode 142.

[0062] An attachment reinforcement hole 123 may be formed on the first heat dissipation terminal 121. The periphery of the attachment reinforcement hole 123 may be soldered or coated with conductive adhesive to improve the bonding strength between the electrode and the terminal.

[0063] The attachment reinforcement portions 124 and 125 can be formed on the first heat dissipation terminal 121 and the second heat dissipation terminal 122, respectively. Each attachment reinforcement portion 124 and 125 corresponds to a region in which the width of the first heat dissipation terminal 121 or the second heat dissipation terminal 122 changes in the Y direction. Similarly, welding or applying conductive adhesive can be performed on the attachment reinforcement portions 124 and 125 to improve the bonding strength between the electrode and the terminal.

[0064] Since one end of the first heat dissipation terminal 121 is in contact with the upper surface of the thermistor element 130, its other end needs to be bent downwards by a distance equivalent to the thickness of the thermistor element 130 in order to make contact with the terminal on the printed circuit board (PCB). (Refer to...) Figure 3 By forming a first bend 126 and a second bend 127 between one end and the other end of the first heat dissipation terminal 121, the other end of the first heat dissipation terminal 121 and the other end of the second heat dissipation terminal 122 can be at the same height and form an electrical surface contact with the terminal on the PCB. Preferably, the bending angle of each of the first bend 126 and the second bend 127 is 90 degrees. However, this application is not limited to this, and the sum of the bending angles of the first bend 126 and the second bend 127 can also be 180 degrees.

[0065] Since the second heat dissipation terminal 122 is in contact with the lower surface of the thermistor element 130, the entire lower surface of the second heat dissipation terminal 122 can contact the terminal on the PCB.

[0066] Based on the mounting surface of the PCB, the height of the circuit protection device 100 disclosed in this application is determined by the sum of the thicknesses of the housing 110, the ceramic plate, the first heat dissipation terminal 121 (0.3 mm) and the second heat dissipation terminal 122 (0.3 mm), and can achieve a thickness of less than 3 mm.

[0067] Reference Figure 5 The housing 110 is used to protect the thermistor element 130 of the circuit protection device 100. The housing 110 can be manufactured by injection molding. Figure 5 As shown, the housing 110 may have a predetermined thickness, or it may be configured to completely fill the internal space of the circuit protection device 100 without leaving any gaps.

[0068] One embodiment of the circuit protection device 100 of this application dissipates heat through conduction, and its heat dissipation structure includes: (i) two large-area electrodes formed on opposite surfaces of a rectangular or circular ceramic plate; (ii) two large-area heat dissipation terminals that are in contact with each electrode; and (iii) a PCB that is in contact with the heat dissipation terminals.

[0069] Furthermore, thanks to its efficient heat dissipation performance, the circuit protection device 100 can achieve high power adaptation through a relatively small thermistor element 130.

[0070] According to one embodiment of this application, the heat generated by the circuit protection device 100 can be efficiently dissipated through the heat dissipation terminal.

[0071] Furthermore, this circuit protection device with an SMD (surface mount device) structure can be applied to ultra-thin wall-mounted TVs.

[0072] The circuit protection device based on the technical concept of this application has effects not limited to those described above. Those skilled in the art will clearly understand other effects not explicitly mentioned through the following description.

[0073] The foregoing has described several embodiments of this application through examples, but the descriptions of each embodiment in the "Detailed Description" section are merely illustrative. Those skilled in the art should understand that various modifications and equivalent implementations can be made based on the above application content without departing from the scope of this application.

[0074] Furthermore, this application is not limited to the embodiments described above and can be implemented in many other forms. The foregoing description is intended to fully disclose this application and enable those skilled in the art to understand its full scope. This application is defined only by the claims.

Claims

1. A circuit protection device, comprising: A surface-mount thermistor element (130) includes a first electrode (141) and a second electrode (142); The first heat dissipation terminal (121) is connected to the first electrode (141); The second heat dissipation terminal (122) is connected to the second electrode (142); and The housing (110) is used to protect the thermistor element (130), the first heat dissipation terminal (121) and the second heat dissipation terminal (122).

2. The circuit protection device according to claim 1, wherein, The thermistor element (130) includes: Rectangular or circular ceramic slabs; and The first electrode (141) and the second electrode (142) are respectively printed on opposite surfaces of the ceramic plate.

3. The circuit protection device according to claim 2, wherein, The first electrode (141) is disposed on the upper surface of the ceramic plate, and the second electrode (142) is disposed on the lower surface of the ceramic plate.

4. The circuit protection device according to claim 3, wherein, One end of the first heat dissipation terminal (121) forms an electrical surface contact with the first electrode (141), and one end of the second heat dissipation terminal (122) forms an electrical surface contact with the second electrode (142).

5. The circuit protection device according to claim 4, wherein, The other ends of the first heat dissipation terminal (121) and the second heat dissipation terminal (122) form electrical surface contact with the corresponding terminals on the PCB.

6. The circuit protection device according to claim 5, wherein, By forming a first bend (126) and a second bend (127) between one end and the other end of the first heat dissipation terminal (121), the other end of the first heat dissipation terminal (121) and the other end of the second heat dissipation terminal (122) are at the same height and form an electrical surface contact with the terminal on the PCB.

7. The circuit protection device according to claim 1, wherein, The first heat dissipation terminal (121) and the second heat dissipation terminal (122) dissipate the heat generated by the thermistor element (130) to the PCB through conduction.

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