Fuse resistor

Abstract

Disclosed is a fuse resistor provided on an electrical circuit to protect the electrical circuit and elements. The fuse resistor includes a substrate on which first and second resistive terminals and fuse terminals are formed, first and second resistive elements surface-mounted on the first and second resistive terminals and dividing applied current or voltage, and a temperature fuse surface-mounted on the fuse terminals and broken by heat generated from the first and second resistive elements. If overcurrent or overvoltage is applied, the first and second resistive elements generate heat and the temperature fuse is broken by the generated heat.

Claims

1. A fuse resistor provided on an electrical circuit to protect the electrical circuit and elements, the fuse resistor comprising: a substrate on which first and second resistive terminals and fuse terminals are formed; first and second resistive elements surface-mounted on the first and second resistive terminals and dividing applied voltage; and a temperature fuse surface-mounted on the fuse terminals to be broken by heat generated from the first and second resistive elements, wherein, the first and second resistive elements are installed at both sides of the temperature fuse, if overcurrent or overvoltage is applied, the first and second resistive elements generate heat and the temperature fuse is broken by the generated heat, and wherein the temperature fuse is physically located substantially between and substantially parallel with the first and second resistive elements, and wherein the first resistive element is not identical with the second resistive element, such that the first resistive element and the second resistive element do not fail simultaneously.

2. The fuse resistor according to claim 1, wherein each of the first and second resistive elements is a wound type resistive element including a resistive body, resistive caps provided at both ends of the resistive body, and a coil wound on the outer circumferential surface of the resistive body.

3. The fuse resistor according to claim 2, wherein the first and second resistive elements have the same resistance value and the coils of the first and second resistive elements have the same diameter.

4. The fuse resistor according to claim 2, wherein the first and second resistive elements have different resistance values and the coils of the first and second resistive elements have different diameters.

5. The fuse resistor according to claim 2, wherein: the resistive body of the first resistive element is smaller than the resistive body of the second resistive element; the coil of the first resistive element has a smaller turn number than the coil of the second resistive element; and if the electrical circuit or the elements mounted on the electrical circuit are abnormally operated, at least the coil of the first resistive element is opened.

6. The fuse resistor according to claim 5, wherein: the first resistive element has a smaller resistance value than the second resistive element and the coil of the first resistive element has a smaller diameter than the coil of the second resistive element; and if the electrical circuit or the elements mounted on the electrical circuit are abnormally operated, at least the coil of the first resistive element is opened.

7. The fuse resistor according to claim 5, wherein, if a short occurs in the electrical circuit or if the elements mounted on the electrical circuit are damaged and aged, at least the coil of the first resistive element is opened.

8. The fuse resistor according to claim 6, wherein, if a short occurs in the electrical circuit or if the elements mounted on the electrical circuit are damaged and aged, at least the coil of the first resistive element is opened.

9. The fuse resistor according to claim 1, wherein: lead wire terminals are formed on the substrate; and surface mount type lead wires are mounted on the lead wire terminals.

10. The fuse resistor according to claim 1, wherein the substrate is provided with a pad which is combined with a main substrate using solder ball.

11. A fuse resistor provided on an electrical circuit to protect the electrical circuit and elements, the fuse resistor comprising: a substrate on which first and second resistive terminals and fuse terminals are formed; first and second resistive elements surface-mounted on the first and second resistive terminals and dividing applied voltage; and a temperature fuse surface-mounted on the fuse terminals to be broken by heat generated from the first and second resistive elements, and wherein the first resistive element is not identical with the second resistive element, such that the first resistive element and the second resistive element do not fail simultaneously.

12. The fuse resistor of claim 11, wherein the first resistive element has a different resistance than the second resistive element.

13. The fuse resistor of claim 11, wherein the first resistive element has a different coil diameter than the second resistive element.

14. The fuse resistor of claim 11, wherein the first resistive element has a different turn number than the second resistive element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a perspective view illustrating a fuse resistor in accordance with one embodiment of the present invention;

(3) FIG. 2 is an exploded perspective view illustrating the fuse resistor in accordance with the embodiment of the present invention;

(4) FIG. 3 is a view illustrating a temperature fuse having a structure differing from a temperature fuse of FIG. 2;

(5) FIGS. 4A to 4C are views illustrating mounting methods of the fuse resistor in accordance with the present invention on a main substrate;

(6) FIGS. 5A and 5B are circuit diagrams illustrating first and second resistive elements in accordance with the present invention, respectively arranged in series and in parallel;

(7) FIG. 6 is a plan view illustrating breaking of the temperature fuse in accordance with the present invention by heat generated from the first and second resistive elements;

(8) FIG. 7 is a plan view illustrating shorts of coils of the first and second resistive elements in accordance with the present invention by surge voltage or abnormal operation of an electrical circuit;

(9) FIG. 8 is a plan view illustrating the first and second resistive elements in accordance with the present invention having different coil diameters and different coil turn numbers; and

(10) FIGS. 9A to 9E are plan views illustrating different arrangements of resistive elements and a temperature fuse on the substrate in accordance with the present invention.

(11) FIG. 10 is a perspective view of a temperature fuse resistor according to conventional art.

DETAILED DESCRIPTION OF THE INVENTION

(12) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings.

(13) With reference to FIGS. 1 and 2, a fuse resistor 100 in accordance with the present invention is designed for use in an electrical circuit of an electronic product, and may generally include a substrate 110, first and second resistive elements 130 and 135, and a temperature fuse 140.

(14) First and second resistive terminals 111 and 113, fuse terminals 115, lead wire terminals 117, and slots 116 are formed on the substrate 110.

(15) Each of the first and second resistive elements 130 and 135 may be a wound type resistive element including a resistive body 131 having a rod shape, resistive caps 133 provided at both ends of the resistive body 131, and a coil 134 wound on the outer circumferential surface of the resistive body 131.

(16) Further, each of the first and second resistive elements 130 and 135 may be an SMD type resistive element without a lead wire so as to be surface-mounted on the first resistive terminals 111 or the second resistive terminals 113. Here, the resistive caps 113 may be fixed to the resistive terminals 111 and 113 of the substrate 110 using a solder paste (not shown).

(17) The temperature fuse 140 is surface-mounted on the fuse terminals 115. When overvoltage or overcurrent is applied and the first and second resistive elements 130 and 135 generate heat, the temperature fuse 140 is broken by the generated heat and thus, serves to intercept electrical connection.

(18) The temperature fuse 140 may be a fuse element of a bar shape including a low melting point metal or alloy having a low melting point of less than 450 C., for example, including at least one of Sn, Ag, Sb, In, Bi, Al, Zn, Cu, and Ni.

(19) For example, as exemplarily shown in FIG. 3, a temperature fuse 140a may include a ceramic tube pipe 141, terminals 142 formed at both ends of the ceramic tube pipe 141, and a fuse wire 143 inserted into the ceramic tube pipe 141.

(20) With reference to FIGS. 1, 2, and 4A, the lead wire terminals 117 formed on the substrate 110 are electrically connected to the first and second resistive terminals 111 and 113 through a circuit pattern (not shown), and surface mount type lead wires 119 having a plate shape are surface-mounted on the lead wire terminals 117.

(21) Further, the surface-mounted lead wires 119 are bent downwardly, fitted into the slots 116, inserted into holes 201 formed on a main substrate 200, and then soldered.

(22) With reference to FIG. 4B, the fuse resistor 100 in accordance with the present invention may be surface-mounted on the main substrate 200. In more detail, a pad 112 is formed on the substrate 110, and a fuse resistor terminal 203 is formed on the main substrate 200. A solder ball 205 is formed on the fuse resistor terminal 203, and the substrate 110 is connected to the main substrate 200 by mounting the pad 112 on the solder ball 205.

(23) With reference to FIG. 4C, a lead wire terminal 118 may be vertically formed through the substrate 110. The lead wire terminal 118 is electrically connected to the first and second resistive terminals 111 and 113 through a circuit pattern (not shown), and a lead wire 119a is soldered under the condition that the lead wire 119a is inserted into the lead wire terminal 118.

(24) FIGS. 5A and 5B are circuit diagrams illustrating the first and second resistive elements in accordance with the present invention, which are respectively arranged in series and in parallel.

(25) The first and second resistive elements 130 and 135 in accordance with the present invention may be connected in series or in parallel.

(26) With reference to FIG. 5A, in accordance with the present invention, the first resistive element 130, the temperature fuse 140 and the second resistive element 135 may be sequentially connected in series, or the first resistive element 130, the second resistive element 135 and the temperature fuse 140 may be sequentially connected in series.

(27) If the first and second resistive elements 130 and 136 are connected in series as such, voltage applied to the fuse resistor 100 is divided and thus, impact due to surge voltage may be reduced.

(28) Further, with reference to FIG. 5B, the first resistive element 130 and the second resistive element 135 may be connected in parallel and then, the temperature fuse 150 may be connected thereto in series.

(29) If the first and second resistive elements 130 and 136 are connected in parallel as such, current applied to the fuse resistor 100 is divided and thus, impact due to inrush current or surge current may be reduced.

(30) However, hereinafter, a configuration in which the first resistive element 130, the temperature fuse 140, and the second resistive element 135 are sequentially connected in series will be described.

(31) Hereinafter, the fuse resistor in accordance with the present invention {circle around (1)} if overcurrent/overvoltage is applied, {circle around (2)} if inrush current is applied, {circle around (3)} if surge voltage exceeding a designated voltage value is applied, and {circle around (4)} if the electrical circuit and the elements are abnormally operated, will be individually described.

(32) First, the fuse resistor 100 in accordance with the present invention may prevent generation of an unnecessarily excessive amount of heat in a normal state.

(33) That is, in case of a conventional fuse resistor, a temperature fuse is broken through heat generated from one resistive element disposed at one side of the temperature fuse and thus, an excessive amount of heat is generated in a normal state in which rated current or rated voltage is applied. On the other hand, in the fuse resistor 100 in accordance with the present invention, the first and second resistive elements 130 and 135 divide voltage or current and may thus disperse heat.

(34) Next, with reference to FIG. 6, in the fuse resistor 100 in accordance with the present invention, for example, when overcurrent of 1 A is continuously applied for a designated time if rated current is 300 mA, the first and second resistive elements 130 and 135 disposed at both sides of the temperature fuse 140 generate heat and transfer the heat to the temperature fuse 140, thus being capable of shortening breaking time of the temperature fuse 140.

(35) Further, in the fuse resistor 100 in accordance with the present invention, if inrush current generated when power is supplied is applied, such current is restricted to current of less than a designated value by the first and second resistive elements 130 and 135, thus protecting the electrical circuit.

(36) Further, with reference to FIG. 7, the first and second resistive elements 130 and 135 are designed so as to withstand predetermined voltage, for example, surge voltage of 6 kV or less, without explosion and, if surge voltage exceeding 6 kV is applied, the coils 134 of the resistive elements 130 and 135 are opened and thus the electrical circuit is protected.

(37) Further, the fuse resistor 100 in accordance with the present invention may protect the electrical circuit even if the electrical circuit or the elements mounted on the electrical circuit are abnormally operated. For example, if a short occurs in the electrical circuit or if the element mounted on the electrical circuit is damaged and aged, the coil 134 of the first resistive element 130 or the coil 134a of the second resistive element 135 is opened and thus protects the electrical circuit.

(38) With reference to FIG. 8, coils 134 and 134a of the first and second elements 130 and 135 in accordance with the present invention may have different diameters and different turn numbers.

(39) For example, the coil 134 of the first resistive element 130 may have a smaller diameter, a smaller turn number and a smaller resistance value, and the coil 134a of the second resistive element 135 may have a larger diameter, a larger turn number and a larger resistance value, as compared to the first resistive element 130.

(40) With reference to FIG. 9E, a resistive body of the first resistive element 130 may be smaller than a resistive body of the second resistive element 134, and a coil of the first resistive element 130 may have a smaller turn number than a coil of the second resistive element 134.

(41) As such, if the first and second resistive elements 130 and 135 are configured such that the coil of the first resistive element 130 has a smaller diameter and a smaller turn number than the coil of the second resistive element 134 (with reference to FIG. 8) or if the first and second resistive elements 130 and 135 are configured such that the resistive body of the first resistive element 130 is smaller than the resistive body of the second resistive element 134 and the coil of the first resistive element 130 has a smaller turn number than the coil of the second resistive element 134 (with reference to FIG. 9E), {circle around (3)} if surge voltage exceeding a designated voltage value is applied and {circle around (4)} if the electrical circuit and the elements are abnormally operated, the coil of the first resistive element 130 is opened and thus, the electrical circuit and the elements are protected.

(42) For example, if the electrical circuit and the elements are abnormally operated, the coil of the first resistive element having relatively small diameter, small turn number and small resistance value is opened and thus, the fuse resistor 100 in the present invention may greatly reduce noise and impact, as compared to the conventional fuse resistor including one resistive element.

(43) With reference to FIGS. 9A to 9E, the first and second resistive element 130 and 135 may be provided plural or singular in number.

(44) For example, one first resistive element 130 and one second resistive element 135 may be disposed at both sides of the temperature fuse 140, as exemplarily shown in FIG. 9A, or plural first resistive elements 130 and plural second resistive elements 135 may be disposed at both sides of the temperature fuse 140, as exemplarily shown in FIG. 9B.

(45) Further, first resistive elements 130 and second resistive elements 135 may not be provided in the same number but may be provided in different numbers according to conditions, as exemplarily shown in FIG. 9C.

(46) Otherwise, a first resistive element 130 and a second resistive element 135 may not have the same size and the same resistance value but may have different sizes and different resistance values, as exemplarily shown in FIGS. 9D and 9E.

(47) Consequently, in the fuse resistor in accordance with the present invention, for example, when overcurrent of 1 A is applied for a designated time if rated current is 300 mA, the first and second resistive elements disposed at both sides of the temperature fuse generate heat and rapidly break the temperature fuse, thus protecting the corresponding circuit.

(48) Further, in the fuse resistor in accordance with the present invention, if inrush current is applied, such current is restricted to designated current by the resistive elements, and if surge voltage is applied or the electrical circuit is abnormally operated, the coils of the resistive elements are opened and thus the circuit is protected.

(49) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.