Signal switching device

Abstract

To provide a signal switching device which can reduce the number of switches and easily search for a route from input to output.SOLUTION: A signal switching device includes: an input signal switching unit 1 for selecting at least one signal from a plurality of input signals and outputting the at least one selected input signal as at least one intermediate signal; and an output signal switching unit 2 for selecting at least one intermediate signal from the at least one intermediate signal output from the input signal switching unit 1 and outputting the at least one selected intermediate signal as at least one output signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a signal switching device. [Background technology]

[0002] When connecting various models to a general-purpose electrical test device for a product, the signal pin layout differs depending on the model, making it impossible to connect them as they are. Therefore, a signal switching device is used to accommodate the differences in pin layout.

[0003] Electrical signal switching devices have been commercially available from many measuring instrument manufacturers. The most commonly used switching device is a crossbar switch, which provides a switch at each intersection of an input signal line and an output signal line. Also known is a signal switching device with a three-stage configuration consisting of an input stage, an intermediate stage, and an output stage, each of which is comprised of multiple matrix switches, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-209622 Summary of the Invention [Problem to be solved by the invention]

[0005] In a crossbar switch, the path connecting the input and output you want to connect is simply a switch where the input signal line and output signal line intersect, making it easy to find a path. On the other hand, when there are N input and output signal lines, the number of switches that make up the crossbar switch is N. 2 Therefore, if the number of input and output signal lines increases, the number of required switches becomes enormous, making it difficult to realize a large-scale signal switching device.

[0006] In the signal switching device described in Patent Document 1, similar to a communication path switching method known as a Clos network, an input signal is divided and input by a small-scale signal switching circuit, an output signal is also divided and output by a small-scale signal switching circuit, and a small-scale signal switching circuit is inserted between the input signal switching circuit and the output signal switching circuit. As a result, when there are N input and output signal lines, the minimum number of switches that make up the entire signal switching circuit is 3N 3 / 2 The method described in Patent Document 1 can greatly reduce the number of switches required compared to crossbar switches, but this is still insufficient. Also, the path search from input to output becomes complicated.

[0007] An object of the present disclosure is to provide a signal switching device that reduces the number of switches and makes it easy to search for a path from an input to an output. [Means for solving the problem]

[0008] The signal switching device of the present disclosure includes an input signal switching unit configured to select one or more input signals from a plurality of input signals and output them as one or more intermediate signals, and an output signal switching unit configured to select one or more intermediate signals from the one or more intermediate signals output from the input signal switching unit and output them as one or more output signals.

[0009] The signal switching device of the present disclosure is a signal switching device including a plurality of signal switching boards, each of which includes N input / output signal lines arranged in a first direction, M intermediate signal lines arranged in a second direction perpendicular to the first direction, (N×M) switches each connecting or disconnecting one of the N input / output signal lines to one of the M intermediate signal lines, input / output terminals connected to the input / output signal lines, and intermediate terminals connected to the intermediate signal lines. The plurality of signal switching boards are connected along the second direction. Opposing intermediate terminals of two signal switching boards adjacent in the second direction are connected.

[0010] A signal switching device according to the present disclosure includes a plurality of signal switching boards and a substrate, wherein the signal switching boards include N input / output signal lines arranged in a first direction, M intermediate signal lines each including a first portion arranged in a second direction perpendicular to the first direction and a second portion arranged in the first direction, (N×M) switches each connecting or disconnecting one of the N input / output signal lines to one of the M intermediate signal lines, a first input / output terminal arranged on a first side of the signal switching board and connected to a first end of the input / output signal line, a second input / output terminal arranged on a second side opposite the first side of the signal switching board and connected to a second end of the input / output signal line, and an intermediate terminal arranged on the second side of the signal switching board and connected to one end of the second portion of the intermediate signal line. The intermediate terminals of the plurality of signal switching boards are connected by wiring on the substrate, and the second input / output terminals of the plurality of signal switching boards are connected by wiring on the substrate. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a signal switching device that reduces the number of switches and facilitates path search from input to output. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating a configuration of a signal switching device according to a first embodiment. [Figure 2] FIG. 1 is a wiring diagram of a crossbar switch. [Figure 3] FIG. 10 is a diagram showing the configuration of a signal switching board 8 according to a second embodiment. [Figure 4] FIG. 10 is a diagram illustrating the configuration of a signal switching device according to a second embodiment. [Figure 5] FIG. 10 is a diagram showing the configuration of a signal switching device according to a third embodiment. [Figure 6] FIG. 11 is a diagram showing the configuration of a signal switching device according to a modified example of the third embodiment. [Figure 7] FIG. 10 is a diagram showing the configuration of a signal switching device according to a fourth embodiment. [Figure 8]FIG. 10 is a diagram showing the configuration of a signal switching board 8 according to a fifth embodiment. [Figure 9] 10 is a diagram showing an example in which a plurality of signal switching boards 8 are mounted on a printed circuit board 11. FIG. [Figure 10] 10 is a diagram for explaining an example of wiring when a plurality of signal switching boards 8 are mounted on a printed circuit board 11. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described with reference to the drawings. Embodiment 1

[0014] The signal switching device according to the first embodiment is used in electrical testing of a product by being inserted between the product being tested and a general-purpose electrical test device.

[0015] In general-purpose electrical test equipment, the type of signal input or output at each pin of the terminal that exchanges electrical signals with the device under test is fixed. However, the pin arrangement of the terminal that exchanges electrical signals with the general-purpose electrical test equipment varies depending on the type of device under test. This not only results in a different signal order, but also in signals that exist only in certain types of devices, resulting in a different number of signal lines. The signal switching device of this embodiment absorbs these differences in pin arrangements and switches signals between the device under test and the general-purpose electrical test equipment so that any device under test can be connected to the general-purpose electrical test equipment. FIG. 1 is a diagram showing the configuration of a signal switching device according to the first embodiment.

[0016] The signal switching device includes an input signal switching unit 1, an output signal switching unit 2, L input signal lines 9(1) to 9(L), M intermediate signal lines 4(1) to 4(M), and N output signal lines 5(1) to 5(N), where L>M and N>M. In the following description, the input signal lines 9(1) to 9(L), intermediate signal lines 4(1) to 4(M), and output signal lines 5(1) to 5(N) may be collectively referred to as the input signal lines 9, intermediate signal lines 4, and output signal lines 5.

[0017] L input signal lines 9(1) to 9(L) are arranged parallel to a first direction. N output signal lines 5(1) to 5(N) are arranged parallel to the first direction. M intermediate signal lines 4(1) to 4(M) are arranged parallel to each other in a direction perpendicular to the first direction. The input signal lines 9(1) to 9(L) transmit input signals. The output signal lines 5(1) to 5(N) transmit output signals. The intermediate signal lines 4(1) to 4(M) transmit intermediate signals.

[0018] The input signal switching unit 1 is configured to select one or more input signals from a plurality of input signals and output the selected input signals as one or more intermediate signals.

[0019] The output signal switching section 2 is configured to select one or more intermediate signals from the one or more intermediate signals output from the input signal switching section 1, and output the selected intermediate signals as one or more output signals.

[0020] The input signal switching unit 1 includes L input terminals I(1) to I(L) and switches 6A(i,j), where 1≦i≦L and 1≦j≦M. In the following description, the input terminals I(1) to I(L) and switches 6A(i,j) may be collectively referred to as input terminal I and switch 6A. Each of the L input terminals I(1) to I(L) can receive an input signal.

[0021] The input signal switching unit 1 is provided with L input signal lines 9(1) to 9(L) connected to input terminals I(1) to I(L), and M intermediate signal lines 4(1) to 4(M).

[0022] The switch 6A(i,j) is disposed at the intersection of the input signal line 9(i) and the intermediate signal line 4(j), and connects or disconnects the input signal line 9(i) and the intermediate signal line 4(j).

[0023] The switch 6A selects one or more input signals from a plurality of input signals and outputs them as one or more intermediate signals.

[0024] The output signal switching unit 2 includes N output terminals O(1) to O(N) and switches 6B(k,j), where 1≦k≦N and 1≦j≦M. In the following description, the output terminals O(1) to O(N) and switches 6B(k,j) may be collectively referred to as output terminal O and switch 6B. Each of the N output terminals O(1) to O(N) can output an output signal.

[0025] The output signal switching unit 2 is provided with N output signal lines 5(1) to 5(N) connected to output terminals O(1) to O(N), and M intermediate signal lines 4(1) to 4(M).

[0026] The switch 6B(k,j) is disposed at the intersection of the output signal line 5(k) and the intermediate signal line 4(j), and connects or disconnects the output signal line 5(k) and the intermediate signal line 4(j).

[0027] The switch 6B(k,j) selects one or more intermediate signals from the one or more intermediate signals output from the input signal switching unit 1, and outputs the selected intermediate signals as one or more output signals. According to the above configuration, desired input signal lines and output signal lines can be electrically connected.

[0028] For example, if the switches 6A(2,1) and 6B(4,1) are turned on at the same time, the input signal line 9(2) and the output signal line 5(4) become conductive.

[0029] The switch 6A can connect N1 input signal lines out of the L input signal lines 9(1) to 9(L) to the N1 intermediate signal lines 4. The switch 6B can connect N1 output signal lines out of the N output signal lines 5(1) to 5(N) to the N1 intermediate signal lines 4, where M≧N1.

[0030] In the signal switching device of this embodiment, the maximum number of input signal lines and output signal lines that can be simultaneously made conductive is M, which is the number of intermediate signal lines 4. In other words, up to M mutually different input signals can be output as up to M mutually different output signals. Generally, in an electrical test, when looking at all test items, it is necessary to connect all arbitrary inputs and arbitrary outputs, but when the test is divided into individual items, the number of signals that require simultaneous connection between arbitrary inputs and arbitrary outputs is limited.

[0031] In addition, the signal switching device of this embodiment can connect multiple input signal lines 9 to one output signal line 5, connect one input signal line 9 to multiple output signal lines 5, or connect multiple input signal lines 9 to multiple output signal lines 5.

[0032] Furthermore, the signal switching device of this embodiment can connect one input signal line 9 to another input signal line 9, or connect one output signal line 5 to another output signal line 5. This can be achieved by simultaneously turning on two switches 6A or two switches 6B. M can be determined according to the electrical test of the product.

[0033] For example, in the first step of a product's electrical test, input signal line 9 (18) is connected to output signal line 5 (17), input signal line 9 (10) is connected to output signal line 5 (19), and input signal line 9 (2) is connected to output signal line 5 (15).

[0034] In the second step of the electrical testing of the product, the input signal line 9(6) is connected to the output signal line 5(16), the input signal line 9(1) is connected to the output signal line 5(4), the input signal line 9(19) is connected to the output signal line 5(17), the input signal line 9(4) is connected to the output signal line 5(2), and the input signal line 9(2) is connected to the output signal line 5(14).

[0035] In the third step of the electrical test of the product, the input signal line 9 (13) is connected to the output signal line 5 (12), and the input signal line 9 (7) is connected to the output signal line 5 (8).

[0036] In such an electrical test, the maximum number of input signals and output signals that can be simultaneously conducted is 5 in the second step. Therefore, M should be set to 5. By making M as small as possible, the circuit scale of the signal switching device can be reduced. Next, the number of switches included in the signal switching device will be described.

[0037] In the signal switching device of this embodiment, the number of switches S1 required is given by the following equation. S1 = LM + NM = (L + N) × M (1) When L and N are equal, the number S1A is given by the following formula: S1A=2×N×M (1A)

[0038] In a crossbar switch having L inputs and N outputs as shown in FIG. 2, the number S2 of switches 6(i, j) required is given by the following equation. S2=L×N (2) When L and N are equal, the number S2A is given by the following formula: S2A=N 2 (2A) The condition for S1 to be smaller than S2 is as follows: M <L×N / (L+N)···(3) The condition for S1A to be smaller than S2A is as follows: M <N / 2···(3A) In the device of Patent Document 1, the number of switches required, S3, is given by the following equation. S3=3N 3 / 2 ···(4) The condition for S1A to be smaller than S3 is as follows. M<3 / 2×N 1 / 2 ···(5)

[0039] Let us consider an example where the total number of signal lines connecting the general-purpose test equipment and the product, i.e., the total number of input signals L and the total number of output signals N, are each 400, there is one power supply and one GND line supplied from the general-purpose test equipment to the product, four signals from the general-purpose test equipment to control the product to set test conditions, and four signals from the product to return test results to the general-purpose test equipment. In this case, M = 10 (= 2 + 4 + 4).

[0040] In the crossbar switch, the number of switches S2A required is 160,000 (=400×400).

[0041] In the device of Patent Document 1, the number of switches required, S3, is 24,000 (3 x 400 3 / 2 ) pieces.

[0042] In the signal switching device of this embodiment, the number of switches S1A required is 8,000 (2 x 400 x 10). In the signal switching device of this embodiment, the number of switches required can be significantly reduced compared to the crossbar switch and the device described in Patent Document 1. The amount of reduction becomes more significant as the number of input / output signals N increases and the number of simultaneously connected signals M required decreases.

[0043] Furthermore, in the signal switching device of this embodiment, searching for a path from input to output is as easy as with a crossbar switch, as it is sufficient to turn on two switches: one at the intersection of the input signal line 9 to be connected and any intermediate signal line 4, and the other at the intersection of this intermediate signal line 4 and the output signal line 5 to be connected.

[0044] As described above, according to this embodiment, in a signal switching device that switches electrical signals, even when the number of input terminals and output terminals for the signals to be switched is large, the number of switches required can be reduced. This makes it possible to reduce the size, weight, and cost of the signal switching device. In addition, it also becomes easier to search for a path from input to output. Embodiment 2 FIG. 3 is a diagram showing the configuration of the signal switching board 8 according to the second embodiment.

[0045] Signal switching board 8 includes N input / output terminals 10(i), M intermediate terminals 7A(j), 7B(j), N input / output signal lines 3(i), M intermediate signal lines 4(j), and N×M switches 6(i, j), where 1≦i≦N and 1≦j≦M. In the following description, input / output terminal 10(i), intermediate terminals 7A(j), 7B(j), input / output signal lines 3(i), intermediate signal lines 4(j), and switches 6(i, j) may be collectively referred to as input / output terminal 10, intermediate terminals 7A, 7B, input / output signal lines 3, intermediate signal lines 4, and switches 6.

[0046] The input / output signal lines 3 are used as input signal lines or output signal lines. The input / output terminals 10 are used as input terminals or output terminals. This allows the signal switching board 8 to be a common signal switching board for both input and output, thereby reducing the design and manufacturing costs of the signal switching device.

[0047] In the following description, it is assumed that within one signal switching board 8, all of the N input / output signal lines 3 are used as either input signal lines or output signal lines, but this is not limited to this.

[0048] The N input / output terminals 10 are arranged on a first side SD1 of the signal switching board 8. The M intermediate terminals 7A are arranged on a second side SD2 of the signal switching board 8. The M intermediate terminals 7B are arranged on a third side SD3 of the signal switching board 8. The first side SD1 and the second side SD2 are adjacent to each other. The second side SD2 and the third side SD3 face each other.

[0049] N input / output signal lines 3(1) to 3(N) are arranged parallel to a first direction. The first direction is a direction perpendicular to the direction of the first side SD1. M intermediate signal lines 4(1) to 4(M) are arranged parallel to a second direction perpendicular to the first direction. The second direction is a direction perpendicular to the directions of the second side SD2 and the third side SD3.

[0050] The N input / output terminals 10 are connected to first ends of the N input / output signal lines 3(1) to 3(N). The M intermediate terminals 7A are connected to the first ends of the M intermediate signal lines 4(1) to 4(M). The M intermediate terminals 7B are connected to the second ends of the M intermediate signal lines 4(1) to 4(M).

[0051] The switch 6(i,j) is disposed at the intersection of the input / output signal line 3(i) and the intermediate signal line 4(j), and connects or disconnects the input / output signal line 3(i) and the intermediate signal line 4(j). FIG. 4 is a diagram showing the configuration of a signal switching device according to the second embodiment.

[0052] The signal switching device includes a first signal switching board 8A and a second signal switching board 8B arranged adjacent to each other, and a wiring group 51. The first signal switching board 8A and the second signal switching board 8B have the same configuration as the signal switching board 8 in FIG.

[0053] The first signal switching board 8A and the second signal switching board 8B are cascade-connected along the second direction. The orientation of the first signal switching board 8A and the orientation of the second signal switching board 8B are 180 degrees different, and the intermediate terminal 7B of the first signal switching board 8A and the intermediate terminal 7B of the second signal switching board 8B face each other. The intermediate terminal 7B of the first signal switching board 8A and the intermediate terminal 7B of the second signal switching board 8B are connected by a wiring group 51. The orientation of the first signal switching board 8A and the orientation of the second signal switching board 8B may be the same, and the intermediate terminal 7B of the first signal switching board 8A and the intermediate terminal 7A of the second signal switching board 8B may face each other.

[0054] The wiring group 51 inputs signals output from the intermediate terminals 7B of the first signal switching board 8A to the intermediate terminals 7B of the second signal switching board 8B. The wiring group 51 inputs signals output from the intermediate terminals 7B of the second signal switching board 8B to the intermediate terminals 7B of the first signal switching board 8A. The wiring group 51 may have M wires and connect the M intermediate terminals 7B of the first signal switching board 8A to the M intermediate terminals 7B of the second signal switching board 8B.

[0055] The first signal switching board 8A can be used as an input signal switching board, and the second signal switching board 8B can be used as an output signal switching board. In this case, input signals are input to the input / output terminals 10 of the first signal switching board 8A. Output signals are output from the input / output terminals 10 of the second signal switching board 8B. By controlling the on / off of the switches 6(i, j) of the first signal switching board 8A and the switches 6(i, j) of the second signal switching board 8B, it is possible to switch which of the N input / output terminals 10 of the second signal switching board 8B each input signal input to the N input / output terminals 10 of the first signal switching board 8A is output from.

[0056] This embodiment makes it possible to configure the signal switching device of embodiment 1 in which the number of input signals and the number of output signals are N and the number of simultaneously connectable signals is M. The first signal switching board 8A can function as the input signal switching unit 1, and the second signal switching board 8B can function as the output signal switching unit 2. Embodiment 3 FIG. 5 is a diagram showing the configuration of a signal switching device according to the third embodiment.

[0057] The signal switching device includes a first signal switching board 8A, a second signal switching board 8B, a third signal switching board 8C, a wiring group 51A, and a wiring group 51B. The first signal switching board 8A, the second signal switching board 8B, and the third signal switching board 8C have the same configuration as the signal switching board 8 in FIG.

[0058] The first signal switching board 8A, the second signal switching board 8B, and the third signal switching board 8C are cascade-connected along the second direction. The orientation of the first signal switching board 8A and the orientation of the second signal switching board 8B are the same, and the orientation of the first signal switching board 8A and the second signal switching board 8B is 180 degrees different from the orientation of the third signal switching board 8C.

[0059] The intermediate terminal 7B of the first signal switching board 8A faces the intermediate terminal 7A of the second signal switching board 8B, and the intermediate terminal 7B of the second signal switching board 8B faces the intermediate terminal 7B of the third signal switching board 8C.

[0060] The intermediate terminals 7B of the first signal switching board 8A and the intermediate terminals 7A of the second signal switching board 8B are connected by a wiring group 51A. The wiring group 51A inputs signals output from the intermediate terminals 7B of the first signal switching board 8A to the intermediate terminals 7A of the second signal switching board 8B. The wiring group 51A inputs signals output from the intermediate terminals 7A of the second signal switching board 8B to the intermediate terminals 7B of the first signal switching board 8A. The wiring group 51A has M wires. Each wire may connect one of the M intermediate terminals 7B of the first signal switching board 8A to one of the M intermediate terminals 7A of the second signal switching board 8B.

[0061] The intermediate terminals 7B of the second signal switching board 8B and the intermediate terminals 7B of the third signal switching board 8C are connected by a wiring group 51B. The wiring group 51B inputs signals output from the intermediate terminals 7B of the second signal switching board 8B to the intermediate terminals 7B of the third signal switching board 8C. The wiring group 51B inputs signals output from the intermediate terminals 7B of the third signal switching board 8C to the intermediate terminals 7B of the second signal switching board 8B. The wiring group 51B has M wires. Each wire may connect one of the M intermediate terminals 7B of the second signal switching board 8B to one of the M intermediate terminals 7B of the third signal switching board 8C.

[0062] The first signal switching board 8A can be used as an input signal switching board, the second signal switching board 8B can be used as an input signal switching board, and the third signal switching board 8C can be used as an output signal switching board. In this case, input signals are input to the input / output terminals 10 of the first signal switching board 8A and the second signal switching board 8B. Output signals are output from the input / output terminals 10 of the third signal switching board 8C.

[0063] By controlling the on / off of the switches 6(i, j) of the first signal switching board 8A, the switches 6(i, j) of the second signal switching board 8B, and the switches 6(i, j) of the third signal switching board 8C, it is possible to switch which of the N input / output terminals 10 of the third signal switching board 8C each input signal input to the N input / output terminals 10 of the first signal switching board 8A and the N input / output terminals 10 of the second signal switching board 8B is output from.

[0064] This embodiment makes it possible to configure the signal switching device of embodiment 1 in which the number of input signals is 2N, the number of output signals is N, and the number of simultaneously connectable signals is M. The signal switching device of this embodiment makes it possible to double the number of signals that can be input compared to the basic configuration of signal switching board 8 in Fig. 3. By increasing the number of signal switching boards 8 in this manner, it is possible to configure a signal switching device in which the number of input signals is an integer multiple of N. The second signal switching board 8B may be used as an output signal switching board, in which case an output signal is output from the input / output terminal 10 of the second signal switching board 8B. A variation of the third embodiment. FIG. 6 is a diagram showing the configuration of a signal switching device according to a modification of the third embodiment.

[0065] The signal switching device includes a first signal switching board 8A, a second signal switching board 8B, a third signal switching board 8C, a wiring group 51A, and a wiring group 51B. The first signal switching board 8A, the second signal switching board 8B, and the third signal switching board 8C have the same configuration as the signal switching board 8 in FIG.

[0066] The first signal switching board 8A, the second signal switching board 8B, and the third signal switching board 8C are cascade-connected along the second direction. The orientation of the second signal switching board 8B is the same as that of the third signal switching board 8C, but the orientation of the second signal switching board 8B and the third signal switching board 8C is 180 degrees different from that of the first signal switching board 8A.

[0067] The intermediate terminal 7B of the first signal switching board 8A faces the intermediate terminal 7B of the second signal switching board 8B, and the intermediate terminal 7A of the second signal switching board 8B faces the intermediate terminal 7B of the third signal switching board 8C.

[0068] The intermediate terminals 7B of the first signal switching board 8A and the intermediate terminals 7B of the second signal switching board 8B are connected by a wiring group 51A. The wiring group 51A inputs signals output from the intermediate terminals 7B of the first signal switching board 8A to the intermediate terminals 7B of the second signal switching board 8B. The wiring group 51A inputs signals output from the intermediate terminals 7B of the second signal switching board 8B to the intermediate terminals 7B of the first signal switching board 8A. The wiring group 51A has M wires. Each wire may connect one of the M intermediate terminals 7B of the first signal switching board 8A to one of the M intermediate terminals 7B of the second signal switching board 8B.

[0069] The intermediate terminal 7A of the second signal switching board 8B and the intermediate terminal 7B of the third signal switching board 8C are connected by a wiring group 51B. The wiring group 51B inputs signals output from the intermediate terminal 7A of the second signal switching board 8B to the intermediate terminal 7B of the third signal switching board 8C. The wiring group 51B inputs signals output from the intermediate terminal 7B of the third signal switching board 8C to the intermediate terminal 7A of the second signal switching board 8B. The wiring group 51B has M wires. Each wire may connect one of the M intermediate terminals 7A of the second signal switching board 8B to one of the M intermediate terminals 7B of the third signal switching board 8C.

[0070] The first signal switching board 8A can be used as an input signal switching board, the second signal switching board 8B as an output signal switching board, and the third signal switching board 8C as an output signal switching board. In this case, an input signal is input to the input / output terminal 10 of the first signal switching board 8A. An output signal is output from the input / output terminals 10 of the second signal switching board 8B and the third signal switching board 8C.

[0071] By controlling the on / off of the switches 6(i, j) of the first signal switching board 8A, the switches 6(i, j) of the second signal switching board 8B, and the switches 6(i, j) of the third signal switching board 8C, it is possible to switch which of the N input / output terminals 10 of the second signal switching board 8B and the N input / output terminals 10 of the third signal switching board 8C each input signal input to the N input / output terminals 10 of the first signal switching board 8A is output from.

[0072] This embodiment makes it possible to configure the signal switching device of embodiment 1 in which the number of input signals is N, the number of output signals is 2N, and the number of simultaneously connectable signals is M. This embodiment makes it possible to double the number of signals that can be output compared to the basic configuration of signal switching board 8 in Fig. 3. By increasing the number of signal switching boards 8 in this manner, it is possible to configure a signal switching device in which the number of output signals is an integer multiple of N. The second signal switching board 8B may be used as an input signal switching board, in which case an input signal is input to the input / output terminal 10 of the second signal switching board 8B.

[0073] It is possible to simultaneously add input signal switching boards 8 to increase the number of input signals in the third embodiment and add output signal switching boards 8 to increase the number of output signals in the modified example of the third embodiment. Furthermore, the intermediate signal lines 4 are connected through all of the input and output signal switching boards 8. For this reason, the order of the input signal switching boards 8 and the output signal switching boards 8 may be configured arbitrarily. Embodiment 4 FIG. 7 is a diagram showing the configuration of a signal switching device according to the fourth embodiment.

[0074] The signal switching device includes a first signal switching board 8A, a second signal switching board 8B, a third signal switching board 8C, a fourth signal switching board 8D, and wiring groups 51A, 51B, 51C, and 51D. The first signal switching board 8A, the second signal switching board 8B, the third signal switching board 8C, and the fourth signal switching board 8D differ from the signal switching board 8 of FIG. 3 in the following points.

[0075] The first signal switching board 8A, the second signal switching board 8B, the third signal switching board 8C, and the fourth signal switching board 8D each include N input / output terminals 10A(i), 10B(i), where 1≦i≦N. In the following description, the input / output terminals 10A(i), 10B(i) may be collectively referred to as input / output terminals 10A, 10B.

[0076] The N input / output terminals 10B are arranged on the fourth side SD4 of the signal switching boards 8A, 8B, 8C, and 8D. The first side SD1 and the fourth side SD4 face each other.

[0077] The N input / output terminals 10A are connected to first ends of the N input / output signal lines 3(1) to 3(N). The N input / output terminals 10B are connected to second ends of the N input / output signal lines 3(1) to 3(N).

[0078] The first signal switching board 8A, the second signal switching board 8B, the third signal switching board 8C, and the fourth signal switching board 8D all face in the same direction.

[0079] The first signal switching board 8A and the third signal switching board 8C are adjacent to each other in a first direction. The second signal switching board 8B and the fourth signal switching board 8D are adjacent to each other in the first direction. The first signal switching board 8A and the second signal switching board 8B are adjacent to each other in a second direction perpendicular to the first direction. The third signal switching board 8C and the fourth signal switching board 8D are adjacent to each other in the second direction.

[0080] The intermediate terminal 7B of the first signal switching board 8A faces the intermediate terminal 7A of the second signal switching board 8B. The intermediate terminal 7B of the first signal switching board 8A and the intermediate terminal 7A of the second signal switching board 8B are connected by a wiring group 51A. The wiring group 51A inputs signals output from the intermediate terminal 7B of the first signal switching board 8A to the intermediate terminal 7A of the second signal switching board 8B. The wiring group 51A inputs signals output from the intermediate terminal 7A of the second signal switching board 8B to the intermediate terminal 7B of the first signal switching board 8A. The wiring group 51A has M wires. Each wire may connect one of the M intermediate terminals 7B of the first signal switching board 8A to one of the M intermediate terminals 7A of the second signal switching board 8B.

[0081] The intermediate terminal 7B of the third signal switching board 8C faces the intermediate terminal 7A of the fourth signal switching board 8D. The intermediate terminal 7B of the third signal switching board 8C and the intermediate terminal 7A of the fourth signal switching board 8D are connected by a wiring group 51B. The wiring group 51B inputs signals output from the intermediate terminal 7B of the third signal switching board 8C to the intermediate terminal 7A of the fourth signal switching board 8D. The wiring group 51B inputs signals output from the intermediate terminal 7A of the fourth signal switching board 8D to the intermediate terminal 7B of the third signal switching board 8C. The wiring group 51B has M wires. Each wire may connect one of the M intermediate terminals 7B of the third signal switching board 8C to one of the M intermediate terminals 7A of the fourth signal switching board 8D.

[0082] The input / output terminals 10B of the first signal switching board 8A face the input / output terminals 10A of the third signal switching board 8C. The input / output terminals 10B of the first signal switching board 8A and the input / output terminals 10A of the third signal switching board 8C are connected by a wiring group 51C. The wiring group 51C inputs signals output from the input / output terminals 10B of the first signal switching board 8A to the input / output terminals 10A of the third signal switching board 8C. The wiring group 51C inputs signals output from the input / output terminals 10A of the third signal switching board 8C to the input / output terminals 10B of the first signal switching board 8A. The wiring group 51C has M wires. Each wire may connect one of the N input / output terminals 10B of the first signal switching board 8A to one of the N input / output terminals 10A of the third signal switching board 8C.

[0083] The input / output terminals 10B of the second signal switching board 8B face the input / output terminals 10A of the fourth signal switching board 8D. The input / output terminals 10B of the second signal switching board 8B and the input / output terminals 10A of the fourth signal switching board 8D are connected by a wiring group 51D. The wiring group 51D inputs signals output from the input / output terminals 10B of the second signal switching board 8B to the input / output terminals 10A of the fourth signal switching board 8D. The wiring group 51D inputs signals output from the input / output terminals 10A of the fourth signal switching board 8D to the input / output terminals 10B of the second signal switching board 8B. The wiring group 51D has M wires. Each wire may connect one of the N input / output terminals 10B of the second signal switching board 8B to one of the N input / output terminals 10A of the fourth signal switching board 8D.

[0084] The first signal switching board 8A is a signal switching board for the first input, the fourth signal switching board 8D is a signal switching board for the first output, the third signal switching board 8C is a signal switching board for the second input, and the second signal switching board 8B is a signal switching board for the second output.

[0085] In this configuration, the N input signal lines of the first signal switching board 8A are connected to the N input signal lines of the third signal switching board 8C, and the N input / output signal lines of the second signal switching board 8B are connected to the N input signal lines of the fourth signal switching board 8D.

[0086] The M intermediate signal lines of the first signal switching board 8A are connected to the M intermediate signal lines of the second signal switching board 8B, and the M intermediate signal lines of the third signal switching board 8C are connected to the M intermediate signal lines of the fourth signal switching board 8D.

[0087] Therefore, this signal switching device has N input signal lines and 2 × M intermediate signal lines. By increasing the number of intermediate signal lines to 2 × M, the number of signals that can be connected simultaneously can be doubled compared to the signal switching board 8 of the basic configuration. In this manner, by increasing the number of combinations of signal switching boards of the basic configuration, the number of signals that can be connected simultaneously can be an integer multiple of M. For example, to increase the number of signals that can be connected simultaneously to three times M, simply place a fifth signal switching board below the third signal switching board 8C and a sixth signal switching board below the fourth signal switching board 8D.

[0088] Furthermore, by combining not only the signal switching board 8 of the basic configuration according to this embodiment, but also a configuration in which the number of input signals is increased according to embodiment 3, a configuration in which the number of output signals is increased according to a modified embodiment of embodiment 3, and a configuration in which the number of input signals and the number of output signals are increased by simultaneously implementing embodiment 3 and a modified embodiment of embodiment 3, it is possible to freely increase the number of input signals, the number of output signals, and the number of simultaneously connected signals.

[0089] The first signal switching board 8A and the third signal switching board 8C may not have the intermediate terminal 7A, and the second signal switching board 8B and the fourth signal switching board 8D may not have the intermediate terminal 7B. Embodiment 5

[0090] In the signal switching devices of the second to fourth embodiments, a large number of signal switching boards 8 are connected in cascade. In this case, the wiring length from the input to the output of the signal switching device becomes long and the path goes through a large number of connectors. Long wiring and the passage through a large number of connectors can cause a decrease in the signal level of the transmitted signal, the introduction of noise, waveform distortion, ringing, etc., resulting in a decrease in signal quality.

[0091] In the fifth embodiment, in order to prevent degradation of signal quality, the signal switching board 8 is connected via a printed circuit board 11. The signal switching device of the fifth embodiment includes a plurality of signal switching boards and a printed circuit board (backboard) on which the plurality of signal switching boards are mounted. FIG. 8 is a diagram showing the configuration of the signal switching board 8 according to the fifth embodiment.

[0092] Signal switching board 8 includes first input / output terminal 10A(i), second input / output terminal 10B(i), intermediate terminal 7(j), N input / output signal lines 3(i), M intermediate signal lines 4(j), and N×M switches 6(i, j), where 1≦i≦N and 1≦j≦M. In the following description, first input / output terminal 10A(i), second input / output terminal 10B(i), intermediate terminal 7(j), input / output signal line 3(i), intermediate signal line 4(j), and switch 6(i, j) may be collectively referred to as first input / output terminal 10A, second input / output terminal 10B, intermediate terminal 7, input / output signal line 3, intermediate signal line 4, and switch 6.

[0093] The N first input / output terminals 10A are arranged on a first side SD1 of the signal switching board 8. The N second input / output terminals 10B are arranged on a second side SD2 of the signal switching board 8. The M intermediate terminals 7 are arranged on the second side SD2 of the signal switching board 8. The second side SD2 faces the first side SD1.

[0094] The N input / output signal lines 3(1) to 3(N) are arranged parallel to a first direction, which is perpendicular to the directions of the first side SD1 and the second side SD2.

[0095] The M intermediate signal lines 4(1) to 4(M) each include a first portion arranged parallel to a second direction perpendicular to the first direction, and a second portion arranged parallel to the first direction.

[0096] The N first input / output terminals 10A are connected to first ends of the N input / output signal lines 3(1) to 3(N). The N second input / output terminals 10B are connected to second ends of the N input / output signal lines 3(1) to 3(N).

[0097] The M intermediate terminals 7 are connected to one ends of the second portions of the M intermediate signal lines 4(1) to 4(M).

[0098] The switch 6(i,j) is disposed at the intersection of the input / output signal line 3(i) and the portion of the intermediate signal line 4(j) that is parallel to the second direction, and connects or disconnects the input / output signal line 3(i) and the intermediate signal line 4(j).

[0099] FIG. 9 is a diagram showing an example in which a plurality of signal switching boards 8 are mounted on a printed circuit board 11. In FIG. The printed circuit board 11 includes a plurality of input / output terminals 10X and intermediate terminals 7X.

[0100] The distance between the input / output terminal 10X and the intermediate terminal 7X of the printed circuit board 11 is the same as the distance between the second input / output terminal 10B and the intermediate terminal 7 of the signal switching board 8. The second input / output terminal 10B of the signal switching board 8 can be joined to the input / output terminal 10X of the printed circuit board 11, and the intermediate terminal 7 of the signal switching board 8 can be joined to the intermediate terminal 7X of the printed circuit board 11. This allows multiple signal switching boards 8 to be mounted on the printed circuit board 11.

[0101] Furthermore, the multiple input / output terminals 10X are connected by wiring on the printed circuit board 11. The multiple intermediate terminals 7X are connected by wiring on the printed circuit board 11. As a result, in order to transmit a signal from one signal switching board 8 to another arbitrary signal switching board 8, it is sufficient to pass the signal through the wiring on the printed circuit board 11, eliminating the need to pass through multiple signal switching boards 8 and multiple connectors.

[0102] FIG. 10 is a diagram for explaining an example of wiring when a plurality of signal switching boards 8 are mounted on a printed circuit board 11. In FIG.

[0103] 10 shows an example in which signal switching boards 8, each with an input / output signal count N of 8 and a simultaneously connected signal count M of 4, are mounted on A×B printed circuit boards 11. Here, A=4 and B=4. The 16 signal switching boards 8 are defined as board a to board p, respectively.

[0104] The boards a to p are classified into A number of GA1 to GA4 according to the first classification, and into B number of GB1 to GB4 according to the second classification.

[0105] In the first classification, B boards "a~d" are classified into group GA1, B boards "e~h" into group GA2, B boards "i~l" into group GA3, and B boards "m~p" into group GA4.

[0106] The pins (A1 to A4) of the four intermediate terminals 7X of the printed circuit board 11 connected to the intermediate terminals 7 of the signal switching boards a to d of the group GA1 are connected by a wiring WM(1).

[0107] The pins (B1 to B4) of the four intermediate terminals 7X of the printed circuit board 11 connected to the intermediate terminals 7 of the signal switching boards e to h of the group GA2 are connected by wiring WM(2).

[0108] The pins (C1 to C4) of the four intermediate terminals 7X of the printed circuit board 11 connected to the intermediate terminals 7 of the signal switching boards i to l of the group GA3 are connected by the wiring WM(3).

[0109] The pins (D1 to D4) of the four intermediate terminals 7X of the printed circuit board 11 connected to the intermediate terminals 7 of the signal switching boards m to p of the group GA4 are connected by a wire WM(4).

[0110] In the second classification, A boards "a, e, i, m" are classified into group GB1, A boards "b, f, j, n" into group GB2, A boards "c, g, k, o" into group GB3, and A boards "d, h, l, p" into group GB4.

[0111] The second input / output terminals 10B of the signal switching boards a, e, i, and m of group GB1 are connected to the pins (E1 to E8) of the four input / output terminals 10X of the printed circuit board 11 by wires WIO(1).

[0112] The second input / output terminals 10B of the signal switching boards b, f, j, and n in group GB2 are connected to the pins (E9 to E16) of the four input / output terminals 10X of the printed circuit board 11 by wires WIO(2).

[0113] The second input / output terminals 10B of the signal switching boards c, g, k, and o of group GB3 are connected to the pins (E17 to E24) of the four input / output terminals 10X of the printed circuit board 11 by wires WIO(3).

[0114] The second input / output terminals 10B of the signal switching boards d, h, l, and p of group GB4 are connected to the pins (E25 to E32) of the four input / output terminals 10X of the printed circuit board 11 by wires WIO(4).

[0115] The intermediate signal line 4 is common to boards "a to d" of group GA1, common to boards "e to h" of group GA2, common to boards "i to l" of group GA3, and common to boards "m to p" of group GA4. Therefore, the signal switching device in Fig. 10 is electrically equivalent to a case in which signal switching boards "abcd" are connected in cascade, signal switching board "efgh" is connected in cascade, signal switching board "ijkl" is connected in cascade, and signal switching board "mnop" is connected in cascade.

[0116] The input / output signal lines 3 are common to the boards "a, e, i, m" of group GB1, common to the boards "b, f, j, n" of group GB2, common to the boards "c, g, k, o" of group GB3, and common to the boards "d, h, l, p" of group GB4. Therefore, the signal switching device of Fig. 10 is electrically equivalent to a case in which the signal switching board "aeim" is connected in cascade, the signal switching board "bfjn" is connected in cascade, the signal switching board "cgko" is connected in cascade, and the signal switching board "dhlp" is connected in cascade.

[0117] 10 is electrically equivalent to a configuration in which boards "a to d" are arranged in the first row and the first to fourth columns, boards "e to h" are arranged in the second row and the first to fourth columns, boards "i to l" are arranged in the third row and the first to fourth columns, and boards "m to p" are arranged in the fourth row and the first to fourth columns. Here, "column" is used to mean the "vertical direction" (first direction), and "row" is used to mean the "horizontal direction" (second direction).

[0118] When transmitting an intermediate signal from board a to board d, a case where boards are connected in cascade will be compared with this embodiment.

[0119] When connected in cascade, the intermediate signal passes through the intermediate terminal three times between boards a and b, between boards b and c, and between boards c and d, and also passes through the wiring within boards b and c, resulting in a long wiring length. In contrast, in this embodiment, the intermediate signal passes through the intermediate terminal only twice, between board a and printed circuit board 11 and between printed circuit board 11 and board d, and the intermediate signal does not pass through the wiring within boards b and c, thereby shortening the wiring length.

[0120] When transmitting an input signal from board a to board m, a case where they are connected in cascade will be compared with this embodiment.

[0121] When connected in cascade, the input signal passes through the input / output terminals three times between boards a and e, between boards e and i, and between boards i and m, and also passes through the wiring within boards e and i, resulting in a long wiring length. In contrast, in this embodiment, the input signal passes through the input / output terminals only twice, between board a and printed circuit board 11 and between printed circuit board 11 and board m, and the wiring length can be shortened because the input signal does not pass through the wiring within boards e and i. Various aspects of the present disclosure are summarized below as appendices.

[0122] (Appendix 1) an input signal switching unit configured to select one or more input signals from a plurality of input signals and output the selected input signals as one or more intermediate signals; an output signal switching unit configured to select one or more intermediate signals from the one or more intermediate signals output from the input signal switching unit and output the selected intermediate signals as one or more output signals.

[0123] (Appendix 2) the input signal switching unit includes a plurality of first switches that connect or disconnect L input signal lines for transmitting a plurality of input signals and M intermediate signal lines for transmitting a plurality of intermediate signals; A signal switching device as described in Appendix 1, wherein the output signal switching unit includes a plurality of second switches that connect or disconnect N output signal lines for transmitting a plurality of output signals to the M intermediate signal lines, where L>M and N>M.

[0124] (Appendix 3) the plurality of first switches are capable of connecting N1 input signal lines among the L input signal lines to N1 intermediate signal lines, respectively; 3. A signal switching device as described in Appendix 2, wherein the plurality of second switches are capable of connecting N1 of the N output signal lines to N1 of the intermediate signal lines, respectively, where M≧N1.

[0125] (Appendix 4) the input signal switching unit and the output signal switching unit each include an intermediate terminal connected to the intermediate signal line, 4. The signal switching device according to claim 2, wherein the intermediate terminals in the input signal switching section and the output signal switching section are connected to the intermediate terminals of the adjacent input signal switching section or the output signal switching section.

[0126] (Appendix 5) 5. The signal switching device according to any one of claims 1 to 4, comprising a plurality of the input signal switching sections or a plurality of the output signal switching sections.

[0127] (Appendix 6) a plurality of the input signal switching units and a plurality of the output signal switching units; the input signal switching unit and the output signal switching unit each include an input / output terminal connected to the input signal line or the output signal line, The signal switching device according to any one of appendices 2 to 5, wherein the input / output terminals in the input signal switching unit and the output signal switching unit are connected to the input / output terminals of the adjacent input signal switching unit or the output signal switching unit.

[0128] (Appendix 7) A signal switching device including a plurality of signal switching boards, The signal switching board comprises: N input / output signal lines arranged in a first direction; M intermediate signal lines arranged in a second direction perpendicular to the first direction; (N×M) switches, each of which connects or disconnects one of the N input / output signal lines to one of the M intermediate signal lines; an input / output terminal connected to the input / output signal line; an intermediate terminal connected to the intermediate signal line; a plurality of the signal switching boards are connected along the second direction; A signal switching device in which the opposing intermediate terminals of two signal switching boards adjacent in the second direction are connected.

[0129] (Appendix 8) A plurality of the signal switching boards are connected along the first direction, 8. The signal switching device according to claim 7, wherein the input / output terminals of two signal switching boards adjacent in the first direction are connected to each other.

[0130] (Appendix 9) A signal switching device comprising a plurality of signal switching boards and a substrate, The signal switching board comprises: N input / output signal lines arranged in a first direction; M intermediate signal lines each including a first portion disposed in a second direction perpendicular to the first direction and a second portion disposed in the first direction; (N×M) switches, each of which connects or disconnects one of the N input / output signal lines to one of the M intermediate signal lines; a first input / output terminal arranged on a first side of the signal switching board and connected to a first end of the input / output signal line; a second input / output terminal arranged on a second side of the signal switching board opposite to the first side and connected to a second end of the input / output signal line; an intermediate terminal disposed on the second side of the signal switching board and connected to one end of the second portion of the intermediate signal line; the intermediate terminals of the plurality of signal switching boards are connected by wiring on the substrate; A signal switching device in which the second input / output terminals of the plurality of signal switching boards are connected by wiring on the board.

[0131] (Appendix 10) A×B number of the signal switching boards are included, The signal switching boards are classified into first to A groups according to a first classification; the intermediate terminals of the B signal switching boards in each of the first to A groups are connected by wiring on the board; The signal switching boards are classified into first to B groups according to the second classification, 10. The signal switching device according to claim 9, wherein the second input / output terminals of A signal switching boards in each of the first to B groups are connected by wiring on the board.

[0132] The above-described embodiments can be combined as appropriate. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0133] 1 input signal switching section, 2 output signal switching section, 3 input / output signal line, 4 intermediate signal line, 5 output signal line, 6, 6A, 6B switches, 7, 7A, 7B, 7X intermediate terminal, 8, 8A, 8B, 8C, 8D, a-p signal switching board, 9 input signal line, 10, 10A, 10B, 10X input / output terminal, 11 printed circuit board, 51, 51A, 51B, 51C, 51D wiring group, I input terminal, O output terminal, WIO, WM wiring.

Claims

1. an input signal switching unit configured to select one or more input signals from a plurality of input signals and output the selected input signals as one or more intermediate signals; an output signal switching unit configured to select one or more intermediate signals from the one or more intermediate signals output from the input signal switching unit and output the selected intermediate signals as one or more output signals.

2. the input signal switching unit includes a plurality of first switches that connect or disconnect L input signal lines for transmitting a plurality of input signals and M intermediate signal lines for transmitting a plurality of intermediate signals; 2. The signal switching device according to claim 1, wherein the output signal switching unit includes a plurality of second switches that connect or disconnect N output signal lines for transmitting a plurality of output signals to the M intermediate signal lines, where L>M and N>M.

3. the plurality of first switches are capable of connecting N1 input signal lines among the L input signal lines to N1 intermediate signal lines, respectively; 3. The signal switching device according to claim 2, wherein the plurality of second switches are capable of connecting N1 output signal lines out of N output signal lines to N1 intermediate signal lines, respectively, where M≧N1.

4. the input signal switching unit and the output signal switching unit each include an intermediate terminal connected to the intermediate signal line, 3. The signal switching device according to claim 2, wherein the intermediate terminals in the input signal switching section and the output signal switching section are connected to the intermediate terminals of the adjacent input signal switching section or the adjacent output signal switching section.

5. 5. The signal switching device according to claim 4, comprising a plurality of said input signal switching sections or a plurality of said output signal switching sections.

6. a plurality of the input signal switching units and a plurality of the output signal switching units; the input signal switching unit and the output signal switching unit each include an input / output terminal connected to the input signal line or the output signal line, 6. The signal switching device according to claim 5, wherein the input / output terminals in the input signal switching section and the output signal switching section are connected to the input / output terminals of the adjacent input signal switching section or the adjacent output signal switching section.

7. A signal switching device including a plurality of signal switching boards, The signal switching board comprises: N input / output signal lines arranged in a first direction; M intermediate signal lines arranged in a second direction perpendicular to the first direction; (N×M) switches, each of which connects or disconnects one of the N input / output signal lines and one of the M intermediate signal lines; an input / output terminal connected to the input / output signal line; an intermediate terminal connected to the intermediate signal line; a plurality of the signal switching boards are connected along the second direction; A signal switching device in which the opposing intermediate terminals of two signal switching boards adjacent in the second direction are connected.

8. A plurality of the signal switching boards are connected along the first direction, 8. The signal switching device according to claim 7, wherein the input / output terminals facing each other of two signal switching boards adjacent in the first direction are connected to each other.

9. A signal switching device comprising a plurality of signal switching boards and a substrate, The signal switching board comprises: N input / output signal lines arranged in a first direction; M intermediate signal lines each including a first portion disposed in a second direction perpendicular to the first direction and a second portion disposed in the first direction; (N×M) switches, each of which connects or disconnects one of the N input / output signal lines and one of the M intermediate signal lines; a first input / output terminal arranged on a first side of the signal switching board and connected to a first end of the input / output signal line; a second input / output terminal arranged on a second side of the signal switching board opposite to the first side, the second input / output terminal being connected to a second end of the input / output signal line; an intermediate terminal disposed on the second side of the signal switching board and connected to one end of the second portion of the intermediate signal line; the intermediate terminals of the plurality of signal switching boards are connected by wiring on the substrate; A signal switching device in which the second input / output terminals of the plurality of signal switching boards are connected by wiring on the board.

10. A×B signal switching boards are included, the signal switching boards are classified into first to Ath groups according to a first classification; the intermediate terminals of the B signal switching boards in each of the first to A groups are connected by wiring on the board; the signal switching boards are classified into first to B groups according to the second classification; 10. The signal switching device according to claim 9, wherein the second input / output terminals of the A signal switching boards in each of the first to B groups are connected by wiring on the board.

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