JPS6024524B2 - Electromagnetic relay for high frequency - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency electromagnetic relay used for switching high frequency circuits.

There is a coaxial relay as an electromagnetic relay for switching secondary and high frequency circuits. This type of coaxial relay has a coaxial switching section and has good high frequency characteristics, but has the drawbacks of being large and expensive. In addition, when trying to use a general electromagnetic relay that is small and inexpensive as a switching relay in a high-frequency circuit, it has the disadvantage that the input/output VSWR is poor due to the lead inductance of the contacts and terminals, and the insertion loss is high. was. In addition, VSWR is an abbreviation of Volta Standing Wave Ratio and is the voltage standing wave ratio.If this is y, then y=(10lrl)/(11lrl)rni(OtsuichiZ's)/(ZI+
Zw) (Z,: load impedance, Z: transmission path impedance). However, r is a reflection coefficient, and when a signal is supplied from a signal source to a load, it takes a value between 0 and 1 depending on the matching conditions between the signal source and the load. (If matching is achieved and there is no signal reflection, it will be 0; if matching is not achieved and all the supplied signals are reflected, it will be 11 or -1) If the signal source and load are matched, reflection will be 0. That is, there is no loss and the VSWR is 1, and as matching becomes impossible, reflection or loss increases, and y approaches infinitely. Figure 1 shows the structure of a switching section of a commonly used electromagnetic relay. In Figure 1, 1 is a shield case, 2 is a common terminal, 2a is a contact piece of the common terminal, 3 is a make terminal, and 4 5 is a break terminal, 5 is a ground terminal, and 6 is a mounting bracket to which an excitation coil (not shown) is attached.

The terminals 2, 3, and 4 are each screw-fastened, and the ground terminal 5 is also fastened to the shield case 1. FIG. 2 shows a high frequency equivalent circuit of the switching section of the electromagnetic relay shown in FIG. The higher the IJ factor, the greater the IJ factor.

Figure 3 shows the frequency characteristics showing this situation, and shows the frequency characteristics of 100M
In the frequency range below Hz, the inductance of the leads of terminals 2, 3, and 4 and the inductance of the contact piece of common terminal 2 are almost negligible, so although the insertion loss of this electromagnetic relay is low, when the frequency exceeds 100 MHz, Since the inductance of the contact piece and the terminal lead cannot be ignored, insertion loss increases as the frequency increases.

As described above, general electromagnetic relays have a large insertion loss in high frequency ranges, and electromagnetic relays alone are not suitable for use in high frequency ranges. In addition, each terminal 2,
If a capacitor is connected between 3 and 4 and the ground terminal 5 to compensate for this drawback, the compensation effect may be weakened or cause variations due to the lead inductance of the connected capacitor itself. In an electromagnetic relay, if a compensation element is inserted outside the electromagnetic relay,
It has been difficult to use general electromagnetic relays in high frequency ranges because the ground current becomes a stray current and causes new problems such as an increase in the area occupied.

The present invention has been made in order to eliminate these conventional drawbacks, and provides a compact and inexpensive high frequency electromagnetic relay that can be used even in a high frequency range.

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6.

FIG. 4 shows the structure of the switching section of the high frequency electromagnetic relay according to the present invention, and the difference from FIG. , 3, and 4 are respectively provided, and the dielectrics 2b, 3b, and 4b are soldered to the shield case through the metallized portions 2c, 3c, and 4c, thereby forming an inductance compensation element, for example. The structure is such that feedthrough capacitors 2A, 3A, and 4A are formed, and the shield case 1 is used as the ground terminal 5.

FIG. 5 shows a high frequency equivalent circuit of the switching section of the power relay shown in FIG.
The capacitance values of 3A and 4A are chosen to cancel the inductance of the bush strips and terminal leads. Further, since the capacitor is a through type, its terminal can be used as it is as a switching terminal for the electromagnetic relay m. The electromagnetic relay according to the present invention having such a structure compensates for the inductance of the cover piece and terminal lead in the high frequency range, so it is not affected by the inductance and is understood from the frequency characteristics shown in Fig. 6. As such, insertion loss is reduced, especially in the high frequency range.

In addition, since the circuit of this electromagnetic relay forms an open circuit within the electromagnetic relay, stray current of ground current does not flow, and since the capacitor is a through type, its terminal can be used as a switching terminal, and it does not require a special area. It has the effect of not causing damage, and allows use of small, inexpensive, general-purpose electromagnetic relays even in high frequency ranges. In addition, in the above embodiment, an electromagnetic relay of the type in which the coaxial cable is directly attached was explained, but as mentioned above, the fact that the capacitor as an inductance compensation element can be built into the relay as a chip type means that the electromagnetic relay that is attached to a printed circuit board can be used. It can also be used for
Similar to the above, we can expect a compact, inexpensive high-frequency electromagnetic relay with low insertion loss and no stray current at high frequencies.

To further explain this, in the equivalent circuit of the conventional relay shown in Figure 2, the signal source impedance is Zs, the load is Z, and the inductance of the relay terminal is L.
In the low frequency region, L0Z-Zs/(L of j + Otsu1Zs) is selected as LI of lj《Z,, LI of lj Zs and ZS=Z, so r=0, that is, there is no reflection. Although matching is achieved, as the frequency increases, the LI of li cannot be ignored, and the loss increases as the frequency increases.
On the other hand, in the case of the present invention shown in FIG.
Assuming the capacitance of A, 4A as C, , C2, C3, capacitor 3
Capacitors 3A and 4A when switched to A side and 4A side respectively
Assuming that one end is grounded, the impedance of the relay contact terminal between capacitors 2A and 3A and 2A and 4A is L, and the combined capacitance of C and C2 is c,
If C is chosen as a value to compensate for the inductance L so that the inductance L is satisfied, then r = (i shin - i saibutsu - ZS) / (i's L - i saibutsu 10 zS) = bud ZS) / ( Z. 10ZS)=.

Therefore, there is no reflection or loss.

As is clear from the above description, according to the present invention, an element that compensates for the inductance of a bush piece or a terminal lead can be built into an electromagnetic relay, or the terminal of the compensation element can be used as an input/output terminal. By adopting such a shape, it is possible to obtain a small and inexpensive electromagnetic relay for high frequencies that has low insertion loss at high frequencies and does not allow stray current to flow.

[Brief explanation of the drawing]

Figure 1 is a plan view and cross-sectional view showing the structure of the switching section of the subordinate electromagnetic relay, Figure 2 is a circuit diagram showing the high frequency equivalent circuit of Figure 1, and Figure 3 is the frequency characteristic of Figure 1. Characteristic diagram,
4 is a plan view and a sectional view showing an embodiment of the present invention, FIG. 5 is a circuit diagram showing the high frequency equivalent circuit of FIG. 4, and FIG.
The figure is a characteristic diagram showing the frequency characteristics of FIG. 4. In the figure, 1 is a shield case, 2 is a common terminal, 2a is a hair piece connected to the common terminal 2, 2b, 3b, 4b are dielectrics, 2c, 3c, 4c are metallized parts, 3 is a make terminal,
4 is a break terminal, 2A, 3A, and 4A are feedthrough capacitors, 5 is a ground terminal, and 6 is a mounting bracket. Note that the same reference numerals in the figures indicate the same or corresponding parts. Rough l drawing 2 drawing 3 drawing 4 drawing 5 drawing 6 drawing

Claims (1)

[Claims] 1. In a high-frequency electromagnetic relay that switches at least two terminals by a contact piece connected to a common terminal, there is a dielectric between the at least two terminals and a shield case in which each of these terminals is attached. 1. A high-frequency electromagnetic relay, characterized in that an inductance compensation element is formed by providing respective bodies to compensate for the inductance of the contact piece and the leads of each terminal. 2. The high frequency electromagnetic relay according to claim 1, wherein the inductance compensation element is a feedthrough capacitor. 3. The high frequency electromagnetic relay according to claim 2, wherein the capacitance value of the feedthrough capacitor is set to a value that cancels out the inductance of the contacts and the leads of each terminal. 4. The high frequency electromagnetic relay according to claim 1, wherein the terminals of the inductance compensation element are used as input/output terminals of the electromagnetic relay. 5. The high frequency electromagnetic relay according to claim 1, wherein a part of the shield case is used as an electromagnetic relay connection terminal.