Circuit protection device

Abstract

This invention provides a circuit protection device with an SMD (surface mount device) structure that has a thickness sufficient for use with thin, wall-mounted TVs. [Solution] The circuit protection device includes a plate-shaped thermistor element 130 including a first electrode 141 and a second electrode 142, a first heat sink terminal 121 connected to the first electrode, a second heat sink terminal 122 connected to the second electrode, and a housing 110 that protects the thermistor element, the first heat sink terminal and the second heat sink terminal.

Description

Technical Field

[0001] The present invention relates to a circuit protection device, and more particularly to a circuit protection device for limiting inrush current during initial driving of an electronic product and preventing fire caused by an increase in internal temperature and overcurrent.

Background Art

[0002] The content presented in this section provides information that forms the background of the present invention and does not constitute prior art.

[0003] Generally, large electronic products such as TVs, air conditioners, washing machines, refrigerators, and dryers include a circuit protection device at the power input end of their electrical circuits to prevent equipment failures caused by excessive pulse values such as inrush current and surge voltage generated when power is applied.

[0004] Inrush current refers to a high-pulse current that temporarily occurs in an electrical circuit at the moment when the power of an electronic product is turned on. A large inrush current exceeds the current limit value of semiconductor elements including diodes used in power supply devices, and the spike voltage generated thereby damages the semiconductor elements.

[0005] FIG. 1 is a circuit diagram of a circuit protection device according to the prior art. An existing circuit protection device includes a resistor (R), a first relay (S1) serially connected to the resistor (R), a resistor (R), and a second relay (S2) parallely connected to the resistor (R) and the first relay (S1). [[ID=?]] [[ID=?]]

[0006] [[ID=?]] When the circuit protection device is powered on and driven, the first relay (S1) is in a closed state and the second relay (S2) is in an open (a) state. After a certain period of time, the first relay (S1) is switched to an open state and the second relay (S2) is switched to a closed (b) state.

[0007] It seems there are some duplicate or incorrect tags in the original text which might cause confusion during translation. I've tried my best to translate it as accurately as possible while maintaining the integrity of the tags. If you have any further questions or need clarification, please let me know.In state (a) of Figure 1, the input current is fed into the electrical circuit via the first relay (S1) and resistor (R). At this time, the resistor (R) limits the inrush current to a predetermined current, causing the inrush current to disappear. After a certain period of time (for example, about 0.5 seconds) has elapsed for the input current to stabilize, the circuit protection device switches to state (b), and the steady-state input current is fed into the electrical circuit via the second relay (S2).

[0008] Existing circuit protection devices like these consist of three components: a resistor (R) and two relatively large relays, a first relay (S1) and a second relay (S2). This results in high costs, frequent malfunctions, and the large amount of space they occupy. Furthermore, the steady-state input current can reach 2-4A or more in the case of washing machines, and 7A or more in the case of dryers. Therefore, high-current relays must be used for both the first relay (S1) and the second relay (S2). However, such high-current relays are expensive, and there is a shortage of commercially available domestic products; in reality, they are mostly imported from Japan and other countries.

[0009] Furthermore, since the first relay (S1) and the second relay (S2) repeatedly open and close each time the electronic product is turned ON / OFF, their durability decreases and malfunctions occur the longer the electronic product is used. Malfunctions of the first relay (S1) and the second relay (S2) can lead to an overcurrent flowing into the electrical circuit, or even cause a fire. Therefore, circuit protection devices that use relays always inherently contain such hazards.

[0010] To solve these problems, circuit protection devices that reduce inrush current using NTC thermistors (Negative Temperature Coefficient Thermistors) are utilized. A thermistor is a device that utilizes the property that the resistivity of a semiconductor changes in response to temperature changes, and among them, an NTC thermistor has the characteristic that its resistance decreases as the temperature rises. An NTC thermistor may include a disc-shaped body, a pair of electrodes formed on opposite sides of the body, and a pair of lead wires soldered to each electrode.

[0011] In the prior art described in Patent Document 1, a ceramic heat dissipation element is disclosed in which an NTC thermistor element is placed in a ceramic case and the ceramic case is filled with a cement-based filler to improve heat dissipation characteristics.

[0012] Conventional ceramic heat sinks like these do not pose significant problems when applied to existing home appliances such as 40-inch TVs with power consumption of less than 200W, and can also be used in home appliances with power consumption of around 200W by connecting 2 to 4 ceramic heat sinks in series. For example, if four ceramic heat sinks are connected in series, and the goal is to control a circuit protection device in a home appliance like a TV with a resistance of approximately 5Ω, each ceramic heat sink will have a resistance of approximately 1.3Ω. Four ceramic heat sinks with a resistance of 1.3Ω will generate more heat than one ceramic heat sink with a resistance of 5Ω (P=I). 2 Since the R (Joule heating) is even smaller, it has advantages in terms of heat management.

[0013] Incidentally, if we were to apply such existing ceramic heat dissipation elements to home appliances that require large power consumption exceeding 200W, such as the recently commercialized TVs larger than 65 inches, it would be necessary to connect five or more ceramic heat dissipation elements with a resistance of less than 1.3Ω in series for heat management. However, in reality, it is difficult to manufacture NTC thermistors with a resistance of less than 1.3Ω, and even if they could be manufactured, they would not be able to exhibit the characteristics of an NTC thermistor if they have a resistance of less than 1.3Ω.

[0014] Therefore, in the case of home appliances that require a large power consumption exceeding 200W, such as TVs larger than 65 inches, it is not possible to simply connect ceramic heat sinks in series as described above. Instead, a single ceramic heat sink with a predetermined resistance value (e.g., 5Ω) to withstand the heat generated by high currents had to be used as a resistor (R) in a conventional circuit using a first relay (S1) and a second relay (S2) as shown in Figure 1.

[0015] However, using the first relay (S1), the second relay (S2), and the ceramic heat sink element in this manner results in high costs, occupies a large amount of space, and retains the mechanical malfunction and durability problems of the first relay (S1) and the second relay (S2) mentioned above. Therefore, there is a real need for improved circuit protection devices.

[0016] Recent TVs tend to get progressively thinner while their screens get larger. As display technology advances, the thickness of ultra-thin TVs will also gradually decrease, but the circuit boards and the circuit components mounted on them pose an obstacle to achieving ultra-thin TVs. In particular, conventional circuit protection devices, due to their thickness, pose a problem in realizing ultra-thin wall-mounted TVs. [Prior art documents] [Patent Documents]

[0017] [Patent Document 1] Korean Registered Patent No. 10-1189853 (October 10, 2012) [Overview of the project] [Problems that the invention aims to solve]

[0018] One problem that this invention aims to solve is to provide a circuit protection device with an SMD structure having a thickness sufficient for application to thin, wall-mounted TVs.

[0019] One problem that this invention aims to solve is to provide a circuit protection device that has an effective heat dissipation structure despite its slim thickness.

[0020] One problem that this invention aims to solve is not limited to the problems described above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0021] To achieve the above object, according to an embodiment of the technical idea of the present invention, there is provided a circuit protection device including: a plate-shaped thermistor element including a first electrode and a second electrode; a first heat dissipation plate terminal connected to the first electrode; a second heat dissipation plate terminal connected to the second electrode; and a housing for protecting the thermistor element, the first heat dissipation plate terminal, and the second heat dissipation plate terminal.

[0022] Further, the circuit protection device can be configured such that the thermistor element includes a rectangular or circular ceramic plate; and the first electrode and the second electrode printed on both surfaces of the ceramic plate, respectively.

[0023] Further, the circuit protection device can be configured such that the first electrode is disposed on the top surface of the ceramic plate among the two surfaces, and the second electrode is disposed on the bottom surface of the ceramic plate among the two surfaces.

[0024] Further, the circuit protection device can be configured such that one end of the first heat dissipation plate terminal is in electrical surface contact with the first electrode, and one end of the second heat dissipation plate terminal is in electrical surface contact with the second electrode.

[0025] Further, the circuit protection device can be configured such that the other ends of the first heat dissipation plate terminal and the second heat dissipation plate terminal are in electrical surface contact with the terminals on the PCB, respectively.

[0026] Further, the circuit protection device can be configured such that the other end of the first heat dissipation plate terminal is in electrical surface contact with the terminal on the PCB at the same height as the other end of the second heat dissipation plate through a primary bend and a secondary bend formed between one end and the other end.

[0027] Further, the circuit protection device can be configured such that the first heat dissipation plate terminal and the second heat dissipation plate terminal release the heat generated from the thermistor element to the PCB through conduction.

[0028] Specific matters of other embodiments are included in the "Specific Content for Implementing the Invention" and the attached "Drawings".

[0029] The advantages and / or features of the present invention, and how they are fulfilled, will become clearer with reference to the various embodiments described in detail later with the accompanying drawings.

[0030] However, the present invention is not limited to the configurations of the embodiments disclosed below, but may also be embodied in a variety of other forms, and each embodiment disclosed herein is merely provided to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined solely by the scope of each claim. [Effects of the Invention]

[0031] According to the present invention, the heat from the circuit protection device is smoothly dissipated through the heat sink terminals.

[0032] Furthermore, the circuit protection device having an SMD structure is applicable to thin wall-mounted TVs. The effects obtained by the circuit protection device according to the technical concept of the present invention are not limited to those described above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. [Brief explanation of the drawing]

[0033] [Figure 1] This is a circuit diagram of a conventional circuit protection device. [Figure 2] This is an illustrative diagram of a circuit protection device according to one embodiment of the present invention. [Figure 3] Figure 2 is an illustrative diagram showing the top surface of the circuit protection device with the housing disassembled. [Figure 4] Figure 2 is an illustrative diagram showing the bottom view of the circuit protection device with the housing disassembled. [Figure 5] Figure 2 is a cross-sectional view of the circuit device depicted. [Modes for carrying out the invention]

[0034] Before describing the present invention in detail, the terms and words used herein should not be interpreted as unconditionally limited to their ordinary or dictionary meanings. The inventors of the present invention may appropriately define and use the concepts of various terms in order to best describe their invention, and these terms and words should be interpreted as meanings and concepts consistent with the technical idea of ​​the present invention.

[0035] In other words, the terms used herein are used to describe preferred embodiments of the present invention and are not intended to specifically limit the scope of the invention. These terms are defined in consideration of the various possibilities of the present invention.

[0036] Furthermore, in this specification, singular expressions can include plural expressions unless the context clearly indicates a different meaning, and similarly, expressions that are plural can include a singular meaning.

[0037] Throughout this specification, when a component is described as "including" another component, unless otherwise stated, it means that it may include any other component, rather than excluding any other component.

[0038] Furthermore, if it is stated that a component is "located inside or connected to" another component, this component may be directly connected to or in contact with the other component, or it may be located at a certain distance apart. In the case where it is located at a certain distance apart, there may be a third component or means for fixing or connecting the component to the other component, and the description of this third component or means may be omitted.

[0039] On the other hand, if one component is described as being "directly connected" or "directly linked" to another component, it should be understood that there is no third component or means.

[0040] Similarly, other expressions describing the relationships between each component, namely "between" and "immediately between," or "adjacent to" and "directly adjacent to," must be interpreted as having the same meaning.

[0041] Furthermore, when terms such as "one side," "the other side," "one side," "the other side," "the first," and "the second" are used in this specification, they are used to clearly distinguish one component from other components, and such terms are not used to restrict the meaning of the component in question.

[0042] Furthermore, where location-related terms such as "up," "down," "left," and "right" are used in this specification, they should be understood to indicate the relative position of the component in the drawing, and these location-related terms should not be understood to refer to absolute positions unless an absolute position is specified for them.

[0043] Furthermore, in this specification, when specifying the reference numeral for each component in each drawing, the same component will have the same reference numeral even if it is shown in other drawings; that is, the same reference numeral throughout the specification will indicate the same component.

[0044] The sizes, positions, and relationships of the components constituting the present invention in the drawings attached herein may be exaggerated, reduced, or omitted in order to clearly convey the concept of the present invention or for the sake of explanatory convenience, and therefore, their proportions and scales are not strictly accurate.

[0045] Furthermore, in describing the present invention below, detailed explanations of configurations that are deemed likely to obscure the gist of the invention, such as prior art and other known technologies, may be omitted.

[0046] Embodiments of the present invention will be described in detail below with reference to the relevant drawings. For the sake of explanation, the left-right direction will be defined as the X-axis, the front-back direction as the Y-axis, and the up-down direction as the Z-axis in the drawings.

[0047] Figure 2 is an illustrative diagram of a circuit protection device according to one embodiment of the present invention.

[0048] Figure 3 is an illustrative diagram showing the top surface of the circuit protection device depicted in Figure 2 with the housing disassembled.

[0049] Figure 4 is an illustrative diagram showing the bottom view of the circuit protection device depicted in Figure 2 with its housing disassembled.

[0050] Figure 5 is a cross-sectional view of the circuit device depicted in Figure 2. The cross-section is shown cut relative to AA' depicted in Figure 2.

[0051] Referring to Figures 2 to 5, a circuit protection device 100 according to one embodiment of the present invention can be configured to include a circuit protection element and a housing 110. The circuit protection element includes a thermistor element 130, a first heat sink terminal 121, and a second heat sink terminal 122.

[0052] The thermistor element 130 is a type of resistor, a semiconductor whose electrical resistance changes significantly with temperature. The thermistor element 130 may include a negative temperature coefficient (NTC) thermistor or a positive temperature coefficient (PTC) thermistor. An NTC thermistor's resistance decreases as the temperature rises. On the other hand, a PTC thermistor's resistance increases as the temperature rises.

[0053] The thermistor element 130, for example, an NTC thermistor, is formed by creating a square-shaped ceramic plate containing multiple types of transition element oxides such as Mn and Ni, applying silver (Ag) paste to both sides of the plate, and baking it to form a first electrode 141 and a second electrode 142, thereby forming a heating element.

[0054] The housing 110 may be made of a plastic with excellent heat insulation properties. The housing 110 may be made of a thermosetting plastic such as melamine resin, epoxy resin, or phenolic resin. Thermosetting plastics are very hard and have excellent heat resistance, so they are used as the material for the housing 110 in embodiments of the present invention.

[0055] A circuit protection device 100 according to one embodiment of the present invention is mounted on a PCB via SMT (surface mount technology). In other words, the circuit protection device 100 corresponds to an SMD (surface mount device) mounted on the surface of the PCB.

[0056] SMT is a type of surface mount technology. DIP type packages use a method where the component's leads penetrate holes in the PCB and are soldered to the other side. Unlike DIP type packages, SMD type packages are mounted directly to the surface of the PCB and attached by soldering. Therefore, the plate-shaped circuit protection device 100 is positioned laterally on the PCB and is directly attached to terminals on the PCB via the heat sink terminals without leads, and is characterized by being able to be realized in a height of 3 mm or less.

[0057] In the prior art, a thermistor can be configured to include a ceramic disk, positive and negative electrodes attached to the ceramic disk, connecting leads connected to the positive electrode, connecting leads connected to the negative electrode, and a covering surrounding the ceramic disk, positive electrode, and negative electrode. In the prior art, the ceramic disk is arranged longitudinally and mounted in a hole in a PCB, with the connecting leads acting as legs supporting the ceramic disk. The prior art thermistor dissipated heat in the form of convection or radiation without a special heat dissipation structure.

[0058] A thermistor element 130 according to one embodiment of the present invention has an ultra-thin structure and includes a special structure that can dissipate heat. The circuit protection device 100 can be configured to include a first heat sink terminal 121 and a second heat sink terminal 122 that electrically contact the first electrode 141 and the second electrode 142 of the thermistor element 130, respectively.

[0059] The first heat sink terminal 121 and the second heat sink terminal 122 are characterized by having the function of terminals that electrically connect the thermistor element 130 and the PCB, and a heat dissipation function that releases heat from the thermistor element 130.

[0060] The thermistor element 130 can be configured to include a rectangular or circular ceramic plate and a first electrode 141 and a second electrode 142 printed on both sides of the ceramic plate, respectively. The first electrode 141 and the second electrode 142 can be formed, for example, by printing a thin film of silver paste (Ag paste) onto the surface of the ceramic plate. Therefore, the first electrode 141 and the second electrode 142 do not increase the thickness of the ceramic plate.

[0061] The first electrode 141 is printed on the top surface of a horizontally arranged ceramic plate, and the second electrode 142 is printed on the bottom surface of a horizontally arranged ceramic plate. The first electrode 141 can occupy 50% or more of the area of ​​the top surface of the ceramic plate. The second electrode 142 can occupy 50% or more of the area of ​​the bottom surface of the ceramic plate.

[0062] The first heat sink terminal 121 and the second heat sink terminal 122 must conduct electricity well and have high heat generation performance, so their material may be aluminum alloy or copper. The first heat sink terminal 121 can electrically contact the first electrode 141, and the second heat sink terminal 122 can electrically contact the second electrode 142. For example, the first heat sink terminal 121 is fixed by soldering while in contact with the first electrode 141. The second heat sink terminal 122 is fixed by soldering while in contact with the second electrode 142. Here, the fixing method is not limited to soldering; for example, a conductive adhesive may also be used.

[0063] The first heat sink terminal 121 and the second heat sink terminal 122 can come into contact with a portion of the first electrode 141 or the second electrode 142 for the convenience of soldering. For example, the first electrode 141 has an exposed portion 143, and the second electrode 142 also has an exposed portion 144. The presence of the exposed portion 143 of the first electrode 141 and the exposed portion 144 of the second electrode 142 allows soldering to be performed without affecting the ceramic plate.

[0064] The first heat sink terminal 121 and the second heat sink terminal 122 may include adhesion-enhancing holes 123 and adhesion-enhancing portions 124 and 125 to increase the bonding force with the first electrode 141 or the second electrode 142.

[0065] Adhesion-enhancing holes 123 may be formed on the first heat sink terminal 121. Soldering may proceed along the area around the adhesion-enhancing holes 123, or a conductive adhesive may be applied to strengthen the bond between the electrode and the terminal.

[0066] The adhesion-enhancing portions 124 and 125 may be formed on the first heat sink terminal 121 and the second heat sink terminal 122, respectively. The adhesion-enhancing portions 124 and 125 correspond to the parts of the first heat sink terminal 121 or the second heat sink terminal 122 where the length in the Y direction, i.e., the width, changes. Similarly, soldering may be performed on the adhesion-enhancing portions 124 and 125, or a conductive adhesive may be applied to strengthen the bonding force between the electrode and the terminal.

[0067] Since one end of the first heat sink terminal 121 is in contact with the top surface of the thermistor element 130, the other end must be refracted by the thickness of the thermistor element 130 in order to contact the terminal on the PCB. Referring to Figure 3, the first heat sink terminal 121 is configured so that the other end can electrically contact the terminal on the PCB at the same height as the other end of the second heat sink terminal 122 through a primary refraction 126 and a secondary refraction 127 formed between the one end and the other end. The primary refraction 126 and the secondary refraction 127 are preferably 90°, but are not limited to this, and the sum of the alternate interior angles of the primary refraction 126 and the secondary refraction 127 is also 180°.

[0068] Since the second heat sink terminal 122 is in contact with the bottom surface of the thermistor element 130, the entire bottom surface of the second heat sink terminal 122 can be in contact with the terminal on the PCB.

[0069] The height of the circuit protection device 100 according to one embodiment of the present invention is configured with respect to the mounting surface of the PCB, including the thickness of the housing 110, the thickness of the ceramic plate, the thickness of the first heat sink terminal 121 (0.3 mm), and the thickness of the second heat sink terminal 122 (0.3 mm), and is characterized in that it can be realized within 3 mm.

[0070] Referring to Figure 5, the housing 110 has the function of protecting the thermistor element 130, which is a component of the circuit protection device 100. The housing 110 can be manufactured in injection form and, as depicted in Figure 5, can have a predetermined thickness or can tightly fill the interior of the circuit protection device 100 without any empty space inside.

[0071] A circuit protection device 100 according to one embodiment of the present invention is characterized by dissipating heat through conduction using two large-area electrodes formed on both rectangular or circular ceramic plates, two large-area heat sink terminals that contact the two electrodes, and a PCB that contacts the two large-area heat sink terminals.

[0072] Furthermore, the circuit protection device 100 is characterized by its ability to handle high power through a relatively small thermistor element 130 due to its smooth heat dissipation.

[0073] Thus, according to one embodiment of the present invention, the heat from the circuit protection device 100 is smoothly discharged through the heat sink terminals.

[0074] Furthermore, the circuit protection device 100 having an SMD structure is applicable to thin, wall-mounted TVs.

[0075] Although various desirable embodiments of the present invention have been described above with some examples, the descriptions of the various diverse embodiments described in the "Specific Details for Carrying Out the Invention" section are merely illustrative, and those skilled in the art will understand from the above description that the present invention can be carried out in various modified forms or equivalent forms.

[0076] Furthermore, since the present invention can be embodied in a variety of other forms, the present invention is not limited by the foregoing description, and the foregoing description is provided to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the present invention, and the present invention is defined solely by the claims of the patent. [Explanation of symbols]

[0077] 100:Circuit protection device 110: Housing 121: 1st heat sink terminal 122: 2nd heat sink terminal 123: Adhesion-enhancing holes 124: Adhesion-enhancing section 125: Adhesion-enhancing section 130: Thermistor element 141: 1st electrode 142:Second electrode 143: Exposed first electrode 144: Exposed second electrode

Claims

1. A plate-shaped thermistor element including a first electrode and a second electrode, A first heat sink terminal connected to the first electrode, The second heat sink terminal connected to the second electrode, The thermistor element, the first heat sink terminal and the second heat sink terminal are protected by a housing, A circuit protection device configured to include a circuit protection device.

2. The thermistor element is A rectangular or circular ceramic plate, The first electrode and the second electrode are printed on both sides of the ceramic plate, The circuit protection device according to claim 1, configured to include:

3. The first electrode is disposed on the top surface of the ceramic plate in the double surface, The circuit protection device according to claim 2, wherein the second electrode is configured to be disposed on the bottom surface of the ceramic plate among the two surfaces.

4. The first heat sink terminal has one end in electrical surface contact with the first electrode, The circuit protection device according to claim 3, wherein one end of the second heat sink terminal is configured to be in electrical surface contact with the second electrode.

5. The circuit protection device according to claim 4, wherein the other ends of the first heat sink terminal and the second heat sink terminal are configured to make electrical surface contact with terminals on the PCB.

6. The first heat sink terminal is, The circuit protection device according to claim 5, wherein the other end is configured to electrically contact the terminal on the PCB at the same height as the other end of the second heat sink terminal through primary and secondary refractions formed between the one end and the other end.

7. The first heat sink terminal and the second heat sink terminal are, The circuit protection device according to claim 1, configured to release heat generated from the thermistor element to the PCB through conduction.

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