JPS5927082B2 - barista - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a varistor which absorbs surge voltages and noise voltages, and which operates effectively against surge noises having high frequency components and provides a lower limiting voltage.

FIG. 1 shows the structure of a conventional varistor.

In the figure, 1 is a disc-shaped balism element, 2 and 7
(2' is not shown) is an electrode baked (or metallized) on both the front and back surfaces of element 1, and 3 and 3' are lead wires electrically connected to electrodes 2 and 2' by soldering, etc. It is. FIG. 2 shows an equivalent circuit when the conventional Varisno shown in FIG. 1 is connected to the power supply line 4, for example.

5 is a varistor element, 6 and w are the above lead wires 3, 3'
is the stray inductance of

Now, when a surge noise voltage is applied between power line 4,
Current flows in the direction of the arrow. At this time, a voltage drop V=-Ldijt occurs due to the floating inductances 6 and 5. Here, L is the lead floating inductance and di/dt is the rate of change of current. Therefore, if the lead wires 3, 3' are long or if the current contains high frequency components, the voltage drop will increase, and the voltage will be superimposed on the limiting voltage of the varisme element 5, and finally The limiting voltage as a terminal voltage increases and the protective effect decreases. The voltage-current characteristic shown in FIG. 3 shows this situation.
In Fig. 3, curve A is the limiting voltage characteristic of only the Varisno element 5.
Curve B is the limiting voltage characteristic in which the voltage drop occurring in the floating inductances 6 and 6' is superimposed on the limiting voltage characteristic of the varisme element 5, and the varismeter shown in Fig. 1 is used for the power supply line 4 etc. as shown in Fig. 2. The limiting voltage characteristic when the voltage is on is curve B. As described above, in conventional varistors, the limiting voltage increases significantly against surge noise voltages including high frequencies, and the protection characteristics thereof are not sufficient.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional art, and is intended to provide a ballismet with excellent characteristics. An embodiment of the present invention will be described below with reference to FIG.

In FIG. 4, 7 is a disk-shaped varistor element mainly made of metal oxide such as ZnO, and 8 and 8 (8' are not shown) are spiral-shaped varistor elements symmetrically provided on both the front and back sides of element 7. The printed coil electrodes 9 and 9a are lead wires taken out from both ends of the printed coil electrode 8.
0 and 10a are lead wires taken out from the back side.

Therefore, the burr in this embodiment has four terminals.
When this varistor is connected between the power supply lines as in the conventional example, its equivalent circuit becomes as shown in FIG. Reference numeral 11 denotes a power supply line, 12 and 17 an inductance formed by the printed coil electrode 8, and 13 an equivalent varistor when the varistor element 7 is viewed from the perspective of a distributed circuit constant.

Next, the principle of operation will be explained.

Now, as in the conventional example, when a surge noise voltage is applied between the power supply lines 11 from the power supply side A, a surge current flows in the direction of the arrow. At this time, the closer the equivalent varistor 13 is to the load side B, the lower the surge noise current becomes. This is because the closer to the load side B, the larger the value of inductance 12, 1Z becomes, and the current is blocked. Therefore, the current density per unit area of the final equivalent varisse 13 located on the load side B is considerably lower than that on the power supply side A. Therefore, the limiting voltage at the load side B terminal becomes low, and the mixing effect becomes large. Not only that, but
Since the variscolumn of this example has four terminals, it is completely unaffected by the voltage drop due to the floating inductance as described above, and has the advantage of being able to obtain the limited voltage of the varisco element 7 itself. Figure 6 shows the voltage-current characteristics of the product of the present invention, where curve A corresponds to curve A in Figure 3, and curve C is the limiting voltage characteristic of the varistor of the present invention, which is superior to the limiting voltage of the varistor itself. ing. Next, an example of test results for the product of the present invention will be explained.

Use a varistor with a voltage of 200V and a noise pulse of 60
0V applied (output impedance 50Ω, rise time 1n
In the case of s), the limited voltage of 436V in the conventional varistor was 376V in the product of the present invention, and 470V and 380V, respectively, when 800V was applied. Here, in the above embodiment, a case was explained in which both electrodes were composed of printed coils 8, 8'. Alternatively, a U-shaped lead wire may be taken out.

In this case, although the effect was slightly lower than that of the example shown in FIG. 4, it was confirmed that it was superior to that of the conventional example. In addition to the spiral pattern shown in FIG. 4, the pattern of the printed coil may also be a meandering printed coil 14 shown in FIG. 7 or a square printed coil 15 shown in FIG. 8.

In addition to the embodiment shown in FIG. 4, when printed coils are formed on both the front and back surfaces of the Paris shiode element, the patterns must be symmetrical with respect to the Paris shiode element. In other words, it is necessary that the opposing positions of both pads be at the shortest distance through the varistor element.
If the pins are not symmetrical, the equivalent varistors 13 in FIG. 5 are arranged in an orderly manner and intersect with each other, thereby increasing the limiting voltage. Furthermore, another embodiment of the present invention is shown in FIG.

The varistor element 7, printed coil 8, and Ff (the handles are not shown in FIG. 9) are the same as those in FIG. 4. In the case of Figure 4,
Since the load current flows through the printed coil 8,
There is a restriction that it is limited to cases where the load current is low, but
The embodiment shown in FIG. 9 solves this problem. 1
The lead wires 6 and 17 are taken out from both sides, and each lead wire 16 and 17 is made of one wire and has a pattern shape similar to that of the printed coils 8 and 8'. It is electrically connected along the line 8' by soldering or the like.

In this way, the load current flows through the lead wires 16 and 17 without flowing through the printed coils 8 and 8'.
By changing the thickness of 6 and 17, the load current capacity can be easily changed. Of course, the effect of reducing the limited voltage mentioned above is maintained. In addition, in order to ensure a certain degree of surge resistance of the varis shio, a part having an electrical resistance higher than the resistance of the conductor forming the printed coil and lower than the resistance of the surface of the varis shio element is added to the gap between the printed coils. It is also possible to print the Aq electrode etc. thinner than the thickness of the printed coil.

On the other hand, instead of forming the printed coil only by the electrode baking pattern, the printed coil can be formed by providing shallow and narrow grooves in the portion corresponding to the coil gap before or after baking the varis element. It is possible to form The present invention is configured as described above, and has the following effects. b) By forming a printed coil on the varistor element and using both ends of the coil as electrical terminals, the current density of the varistor is reduced, making it possible to ignore the voltage drop due to stray interference in the lead wire, which limits the The voltage is significantly reduced and the protection characteristics are improved.

(b) By making the two printed coils symmetrical, the current path becomes orderly, which is effective in reducing the limiting voltage.

c) Application to various load currents is possible by soldering lead wires along the printed coil.

D) Surge resistance is improved by adding a portion between the printed coils that has an electrical resistance higher than the resistance of the conductor forming the printed coil and lower than the resistance of the surface of the varistor element.

e) By configuring the resistance between the printed coils with grooves, perfect insulation is maintained and the characteristics of the printed coils are more clearly demonstrated.

[Brief explanation of drawings]

Fig. 1 is a front view of a conventional varistor, Fig. 2 is an equivalent circuit diagram showing an application example of the varistor, Fig. 3 is a voltage-current characteristic diagram of the varistor, and Fig. 4 is a diagram according to the present invention. A front view showing an example of the varistor, FIG. 5 is an equivalent circuit diagram showing an example of application of the varistor, and FIG. 6 is a voltage-current characteristic diagram of the varistor.
7 and 8 are bar diagrams showing a modified example of the printed coil constituting the varistor, and FIG. 9 is a front view showing another embodiment of the varistor according to the present invention. 7... Balisshio element, 8, 8/, 14, 15.
...Print coil, 9, 9a, 10, 10a,
16, 17... Lead wire.

Claims (1)

[Scope of Claims] 1. A varistor characterized in that at least one electrode of a varistor element mainly made of a metal oxide such as ZnO is constituted by a printed coil, and electrical terminals are taken out from both ends of the printed coil. 2. The varistor according to claim 1, wherein the two electrodes are formed of printed coils, and these printed coils have mutually symmetrical pattern shapes. 3. A patent claim characterized in that a single lead wire having the same shape as the printed coil is electrically connected along the printed coil, and both ends of this lead wire are used as electrical terminals. The varistor according to range 1 or 2. 4. Claims 1 or 2, characterized in that a portion having an electrical resistance higher than the resistance of the conductor forming the printed coil and lower than the resistance of the surface of the varistor element is added to the gap between the printed coils. Barista listed. 5. The varistor according to claim 1 or 2, wherein a groove is provided in the varistor element to constitute a resistance between the printed coils.