JPH04273619A - Switching device - Google Patents

Abstract

PURPOSE:To reduce the waveform distortion of a transmission signal by making an impedance viewing from each output terminal equal to the characteristic impedance of a transmission system at all times. CONSTITUTION:A switching circuit 10 changes over a switch 11 to connect an input terminal 15 to a switching circuit connection signal line 31 and a switch 12 to connect an output terminal 16 to a switching circuit connection signal line 32, then a switching circuit 201 changes over a switch 211 to connect an input terminal 251 to the switching circuit connection signal line 32 and changes over a switch 221 to connect an output terminal 261 to the switching circuit connection signal line 31. Simultaneously, the switches 221, 231 of the switching circuit 201 disconnect switching circuit connection signal lines 411, 412.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention is utilized in a signal path switching device for electrical signals. In particular, it relates to a switching device with redundant signal paths in order to improve reliability.

0002

2. Description of the Related Art FIG. 2 is a block diagram of a conventional switching device.

Conventionally, switching devices have had a configuration in which a plurality of switching devices are connected in parallel, as shown in FIG.

In FIG. 2, it is desirable to keep the characteristic impedance of the transmission system constant from the viewpoint of minimizing waveform distortion of signals transmitted through the transmission system. For this reason, in order to make the impedance seen from the output terminals 16, 261, 262 the same as the characteristic impedance of the transmission system,
It is necessary to terminate the input terminals 15, 251, 252 with an element having characteristic impedance.

Here, when the connection path from the input terminal 15 to the output terminal 16 is switched from the input terminal 15 to the output terminal 261, the switching circuit connection signal lines 51 and 52 are connected to the input terminal 15 and the output terminal 16, respectively. be done. At this time, since the switching circuits 101 to 103 are connected in parallel, the switching circuit connection lines 61 and 62 are also connected to the input terminal 15 and the output terminal 16, respectively. However, since the switching circuit connection lines 61 and 62 are unloaded, the impedance seen from the output terminal 16 becomes different from the characteristic impedance of the transmission system due to the influence of the stray capacitance of the switching circuit connection signal lines 61 and 62. It had the disadvantage of causing distortion in the transmitted signal.

The present invention solves the above-mentioned drawbacks by providing a switching device that can always make the impedance seen from each output terminal equal to the characteristic impedance of the transmission system and reduce waveform distortion of the transmission signal. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention provides a first switch having a common contact connected to a first input terminal and a break contact connected to a first output terminal; an integer greater than or equal to 2, including a first switching circuit including a second switch connected to the second input terminal and a third switch having the common contact connected to the second input terminal and the break contact connected to the second output terminal; n second switching circuits, each of the second switching circuits has a fourth switch whose make contact is connected to the second output terminal, and a fourth switch whose common contact is connected to the third output terminal. and a fifth switch connected to the make contact of the switch of the first switch and the make contact of the second switch, and the fourth switch and the fifth switch of the first and second switching circuits. A pair of first connection signal lines respectively connecting between the common contacts, and a fourth switch and a fourth switch of the (j-1)th (j is an integer between 2 and n) second switching circuit. A pair of second connection signal lines each connecting between the break contact of the fifth switch and the common contact of the fourth switch and the fifth switch of the j-th second switching circuit. Features.

Further, in the present invention, the common contact of the first switch is connected to the first output terminal instead of the first input terminal, and the common contact of the second switch is connected to the first output terminal instead of the first input terminal. a common contact of the third switch is connected to the first input terminal instead of the output terminal; a common contact of the third switch is connected to the second output terminal instead of the second input terminal; A contact can be connected to the second input terminal instead of the second output terminal.

Furthermore, in the present invention, n can be 2.

0010

[Operation] The first switching circuit switches the first switch to connect the first input terminal to one of the pair of first connection signal lines, and switches the second switch to connect the first output terminal to the pair of first connection signal lines. When connected to the other first connection signal line, the first second switching circuit switches the third switch to connect the second input terminal to the other first connection signal line, and Switch No. 4 to connect the second output terminal to one of the first connection signal lines. At the same time, the fourth switch and the fifth switch of the first second switching circuit disconnect the pair of second connection signal lines. The same applies to the (j-1)th second switching circuit.

As described above, the impedance seen from each output terminal can always be made equal to the characteristic impedance of the transmission system, and waveform distortion of the transmission signal can be reduced.

0012

Embodiments Examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a switching device according to an embodiment of the present invention. In FIG. 1, the switching device includes the switch 11 and the common contact as a first switch, with the common contact connected to the input terminal 15 as the first input terminal and the break contact connected to the output terminal 16 as the first output terminal. Switch 1 as a second switch connected to this output terminal 16
A switching circuit 10 as a first switching circuit including 2, and input terminals 251, 252 whose common contacts are second input terminals.
Switching circuits 201 , 202 are provided as two second switching circuits including switches 211 , 212 as third switches connected to output terminals 261 , 262 as second output terminals and having break contacts connected to output terminals 261 , 262 as second output terminals.

The feature of the present invention is that the make contacts of the switching circuits 201 and 202 are connected to the output terminal 26.
1 and 262 as the fourth switch, and the common contact is the switch 211.
, 212 as a fifth switch connected to the make contacts of switches 11 and 12, and the make contacts of switches 11 and 12 and the switches 221 and 231 of the first switching circuit 201.
Switching circuit connection signal lines 31 and 32 serve as a pair of first connection signal lines that respectively connect between the common contacts of the first switching circuit 201 and the break contacts of switch 221 and switch 231 of the first switching circuit 201 and the second switching circuit. Switching circuit connection signal lines 411 and 421 are provided as a pair of second connection signal lines that respectively connect between the common contacts of switch 222 and switch 232 of switch 202.

The operation of the switching device having such a configuration will be explained. In FIG. 1, the connections between the input terminals 15, 251 and the output terminals 16, 261 when no switching is performed are shown by solid lines, and the connections during switching are shown by broken lines. When switching is performed, the switching circuit connection signal lines 411 and 412
can be separated from input terminal 15 and output terminal 16. Therefore, input terminals 15, 251, 252
If it is terminated with an element having the same impedance as the characteristic impedance of the transmission system, the impedance seen from the output terminal 16 can always be made almost equal to the characteristic impedance of the transmission system, regardless of whether a switching operation is performed.

Further, in this embodiment, the case where there are two switching circuits 20 has been described, but the number of switching circuits 20 may be n.

Furthermore, the input terminal 15 and the output terminal 16 may be interchanged, and the input terminal 25 and the output terminal 26 may be interchanged.

[0017]

[Effects of the Invention] As explained above, the present invention has the excellent effect of making it possible to always make the impedance seen from each output terminal equal to the characteristic impedance of the transmission system, and reducing the waveform distortion of the transmission signal. There is.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a switching device according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a conventional switching device.

[Explanation of symbols]

10, 101 to 103, 201 to 202 switching circuits 11, 111 to 113, 12, 121 to 1
23 , 211 - 231 , 212 - 232
Switches 15, 251, 252 Input terminals 16, 261
, 262 Output terminals 31, 32, 411, 412
, 421 , 422 , 51 , 52 , 61 , 62
Switching circuit connection signal line

Claims (3)

[Claims] 1. A first switch having a common contact connected to a first input terminal and a break contact connected to a first output terminal; and a second switch having a common contact connected to the first output terminal. and n second switching circuits, an integer greater than or equal to 2, each including a third switch having a common contact connected to the second input terminal and a break contact connected to the second output terminal. In the switching device, each of the second switching circuits includes a fourth switch having a make contact connected to the second output terminal, and a fourth switch having a common contact connected to the make contact of the third switch. and a fifth switch connecting the make contacts of the first switch and the second switch to the fourth switch and the fifth common contact of the first and second switching circuits, respectively. A pair of first connection signal lines, the break contacts of the fourth switch and the fifth switch of the (j-1)th (j is an integer from 2 to n, inclusive) second switching circuit, and the jth switch. A switching device comprising: a pair of second connection signal lines respectively connecting between the fourth switch and the common contact of the fifth switch of the second switching circuit. 2. A common contact of the first switch is connected to the first output terminal in place of the first input terminal, and a common contact of the second switch is connected to the first output terminal in place of the first output terminal. is connected to the first input terminal, a common contact of the third switch is connected to the second output terminal instead of the second input terminal, and a make contact of the fourth switch is connected to the second output terminal instead of the second input terminal. The switching device according to claim 1, wherein the switching device is connected to the second input terminal instead of the second output terminal. 3. The switching device according to claim 1, wherein said n is 2.