JP2000322993A - Protective element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow certain protection interlocking with the other element by arranging so as to fuse a second element for protecting a circuit from ambient temperature, according to a temperature of a first element generating heat corresponding to flowing current and according to ambient temperature. SOLUTION: A protective element 100 protects a power supply device, because when over current flows through a zener diode 101 connected to a secondary winding of a transformer in the power supply device, a temperature fuse 102 senses heat generation of the zener diode 101, fuses it, and cuts off current supplied to a primary winding of the transformer. In the protective element 100, because the zener diode 101 and the temperature fuse 102 are stored in the same package 103, and therefore dispersion between thermal diffusions of the zener diode 101 and the temperature fuse 102 is null, dispersion between zener current flowing through the zener diode 101 and fusion of the temperature fuse 102 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection element, and more particularly, to a protection element used in a circuit having an element that generates heat according to a flowing current and an element that blows according to a temperature.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional example. The conventional power supply device 1 converts an AC voltage supplied from an AC power supply 2 into a predetermined DC voltage and supplies the DC voltage to a load 3.
The power supply device 1 includes a transformer 4, a photocoupler 5, a primary circuit section 6, and a secondary circuit section 7. The primary side circuit section 4 includes a fuse 8, capacitors C1 to C8, and resistors R1 to R1.
R4, diodes D1 and D2, coil L0, bridge diode 9, thermal fuse 10, and control circuit unit 11.

The transformer 4 has a primary winding L1, a secondary winding L
2. It is composed of an auxiliary winding Ls. The primary winding L1 is 1
The secondary circuit 6 is connected, and the current flowing through the primary circuit 6 is controlled. The secondary winding L2 has a primary winding L1.
Power is transmitted from the The secondary winding L2 is connected to the secondary side circuit 7, and the secondary side circuit 7 generates an output and detects the output.

The photocoupler 5 is connected between the primary side circuit 6 and the secondary side circuit 7 and supplies the detection result of the output from the secondary side circuit 7 to the primary side circuit 6. As described above, the primary circuit 6 and the secondary circuit 7 are connected to the transformer 4 and the photocoupler 5.
And are insulated from each other. The primary side circuit section 6 rectifies the AC voltage from the AC power supply 2 and controls the current flowing through the primary winding L1 of the transformer 4 according to a control signal supplied from the photocoupler 5.
The primary side circuit section 6 is provided with a temperature fuse 10 between the primary winding L1 of the transformer 4 and the control circuit section 11. The thermal fuse 10 blows according to the ambient temperature.
When the ambient temperature rises to a temperature at which the thermal fuse 10 blows, the thermal fuse 10 blows. Thermal fuse 1
When 0 is blown, the supply of current to the primary winding L1 of the transformer 4 is cut off. The thermal fuse 10 is arranged and used so as to be tied to an element that generates heat.

When the supply of current to the primary winding L1 of the transformer 4 is cut off, the operation of the transformer 4 stops, and power is not supplied to the output side. For this reason, the ambient temperature decreases. As described above, the temperature fuse 10 protects the device from a rise in temperature. As the control circuit section 11, a self-excited circuit or a commercially available switching element with a control circuit is used. For example, “MIP022” manufactured by Matsushita Electronics Corporation
2SU "is used.

The secondary side circuit section 7 includes capacitors C11 to C1.
7, resistors R11 to R18, diodes D11 and D12, Zener diodes D13 and D14, coil L10, transistor Q
1. It is composed of a detection IC 12. The secondary side circuit unit 7 generates an output from the power transmitted from the primary winding L1 of the transformer 4 to the secondary winding L2, supplies the output to the load 3, and detects the output supplied to the load 3, The photo coupler 5 is driven. The Zener diode D14 prevents the output from becoming higher than the Zener voltage when an overvoltage occurs.
Is protected from overvoltage.

As the detection IC 12, a commercially available IC for detecting constant voltage and constant current can be used. In the power supply device 1 configured as described above, the primary winding L1 of the transformer 4
The primary side circuit section 6 connected to the side and the secondary side circuit section 7 connected to the secondary winding L2 side of the transformer 4 need to be insulated from each other. From the secondary side circuit part 7 to the primary side circuit part 6
Supplied to

[0008]

However, in the conventional power supply device, the thermal fuse is formed of a discrete component, and is provided in the primary side circuit section 6, and detects an overcurrent or the like based on an ambient temperature. Since the configuration is such that protection is applied, the operating environment changes depending on the installation location, and there is a problem that it is difficult to determine where the installation location is.

Further, since it is necessary to separately assemble the circuit board, there is a problem that the assembling process becomes complicated. The present invention has been made in view of the above points, and an object of the present invention is to provide a protection element that can reliably protect in conjunction with another element.

[0010]

According to the present invention, there is provided a first element 101 which generates heat according to a flowing current, and a second element 102 which melts according to an ambient temperature and protects a circuit from the ambient temperature.
And the second element 102 is arranged to be blown according to the temperature of the first element 101.

According to the present invention, by causing the second element 102 to melt according to the temperature of the first element 101, when an overcurrent flows through the first element 101 and heat is generated, The second element 102 is blown to cut off the supply of current, so that protection can be performed. According to the present invention, the first element 101 and the second element 102 are housed in the same package 103 in an insulated state.

According to the present invention, the first element 101 and the second element
Of the first element 101 and the second element 102 is reduced, and the current flowing through the first element 101 and the current flowing through the second element 102 are reduced. Variation in fusing can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing one embodiment of the present invention. The protection element 100 of this embodiment includes a Zener diode 101 and a thermal fuse 102 in the same package 1.
03. Note that the Zener diode 10
1 corresponds to the first element in the claims, the thermal fuse 102 corresponds to the second element in the claims, and the package 103 corresponds to the package in the claims.

The appearance of the protection element 100 has, for example, the same shape as a commercially available photocoupler. FIG. 2 is an external view of a protection element according to one embodiment of the present invention. As shown in FIG. 2, a Zener diode 101 and a thermal fuse 102 are sealed in a resin package 104, and each terminal T1 to T4 is extended out of the resin package 104 as output pins P1 to P4. I have.

The Zener diode 101 has an anode connected to the output terminal T1 and a cathode connected to the output terminal T2. The thermal fuse 102 has one end connected to an output terminal T3 different from the output terminals T1 and T2,
The other end is connected to an output terminal T4 different from the output terminals T1 and T2, and the Zener diode 101 and the thermal fuse 102 are insulated from each other in the same package 1.
03 is stored.

Zener diode 10 of protection element 100
The output terminals T1 and T2 connected to 1, for example, are connected to both ends of a secondary winding of a transformer of a power supply device, and are used as overvoltage detection elements. Output terminals T3 and T4 connected to the thermal fuse 102 of the protection element 100 are connected in series to, for example, a primary winding of a transformer of a power supply device,
It is used to cut off the current flowing through the primary winding of the transformer 4 according to the ambient temperature and protect the power supply device.

That is, the protection element 100 is a Zener diode 1 connected to a secondary winding of a transformer of a power supply device.
01, an overcurrent flows and heat is generated.
Senses the heat generated by the Zener diode 101, blows it out, cuts off the current supplied to the primary winding of the transformer, and thereby cuts off the supply of power to the secondary winding, thereby protecting the device.

Next, a power supply device using the protection element 100 will be described. FIG. 3 shows a block diagram of a power supply device to which the protection element according to one embodiment of the present invention is applied. 4, the same components as those of FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted. The power supply device 200 includes a thermal fuse 102 and a Zener diode 101 connected to the protection element 100 of the present invention.
It consists of.

According to the power supply device 200, when the output voltage rises and the overvoltage state occurs, the Zener diode 101 enters the overcurrent state. When the Zener diode 101 enters an overcurrent state, it generates heat at a high temperature. Zener diode 1
When the temperature of the thermal fuse 102 reaches the fusing temperature of the thermal fuse 102, the thermal fuse 102 is blown. Thermal fuse 1
02 is connected in series to the primary winding L1 of the transformer, so that no current flows through the primary winding L1 of the transformer when the thermal fuse 102 blows.

Therefore, the two windings from the primary winding L1 side of the transformer
Power is not transmitted to the next winding L2 side, and the power supply device is protected from overcurrent. At this time, in a power supply device using a commercial power supply as a power supply, since it is necessary to insulate the input and output, the Zener diode 101 connected to the secondary winding L2 side of the transformer and the primary winding L1 of the transformer are used. It is necessary to insulate the thermal fuse 102 connected to the side, but in the protection element 100 of the present invention, the Zener diode 101 and the thermal fuse 102 are insulated and packaged in the package 103 as described above. Even if the protection element 100 is used as the Zener diode 101 and the thermal fuse 102, the primary winding L1 and the secondary winding L2 of the transformer can be arranged in an insulated state.

In the protection element 100 of this embodiment, since the Zener diode 101 and the thermal fuse 102 are housed in the same package 103, there is no variation in heat diffusion between the Zener diode 101 and the thermal fuse 102. Variation between the Zener current flowing through the Zener diode 101 and the blowing of the thermal fuse 102 can be reduced.

Furthermore, since the Zener diode 101 and the thermal fuse 102 are housed in the same package 103 and can be handled as a one-chip IC, the protection element 100 of this embodiment can be easily assembled on a substrate or the like. Become. In this embodiment, the power supply device 200 as shown in FIG. 3 has been described as an application example of the protection element 100. However, the power supply device 200 as shown in FIG.
However, the present invention is not limited to this, and can be applied to, for example, a circuit in which a thermal fuse and a Zener diode are built.

In this embodiment, the thermal fuse and the Zener diode are mounted in the same package. However, the present invention is not limited to the Zener diode, and a combination with a normal diode or transistor can be considered.

[0024]

As described above, according to the present invention, when the second element is blown in accordance with the temperature of the first element, an overcurrent flows through the first element to generate heat. To
It has features such as the fact that the second element can be blown to cut off the supply of current to provide protection.

According to the present invention, the first element and the second element
The first element is stored in the same package as the first element.
This has the advantage that the variation in the thermal diffusion between the element and the second element is reduced, and the variation in the current flowing through the first element and the variation in the fusing of the second element can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an external view of a protection element according to one embodiment of the present invention.

FIG. 3 is a block diagram of a power supply device to which the protection element according to one embodiment of the present invention is applied.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

 2 AC power supply 3 Load 4 Transformer 5 Photocoupler 6 Primary circuit 7 Secondary circuit 100 Protection element 101 Zener diode 102 Thermal fuse 103 Package 200 Power supply

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Osamu Ichiki, Inventor Osamu Ichizuka, Fukuoka Pref. EE05 FF10 KK02

Claims (4)

[Claims] A first element that generates heat in accordance with a flowing current; and a second element that melts in accordance with an ambient temperature and protects a circuit from the ambient temperature. A protection element, wherein the protection element is arranged so as to blow the second element accordingly. 2. The protection element according to claim 1, wherein the first element and the second element are housed in the same package in an insulated state. 3. The protection element according to claim 1, wherein the first element is a Zener diode. 4. The protection element according to claim 1, wherein the second element is a thermal fuse.