JP4304091B2 - Signal input circuit and relay unit circuit - Google Patents

Description

  The present invention relates to a signal input circuit and a relay unit circuit corresponding to PNP output and NPN output.

For example, a detection switch such as a multi-optical axis photoelectric switch has a type in which an operation signal output according to the detection operation is output to the outside via an open collector circuit of a PNP transistor, and an open collector circuit of an NPN transistor There is a type that outputs to the outside via the. Patent Document 1 below discloses that one multi-optical axis photoelectric switch can be connected to a PNP output type and an NPN by selectively connecting a PNP output adapter and an NPN output adapter to the multi-optical axis photoelectric switch body. A technique that can be properly used for an output type is disclosed.
JP 2003-255054 A

  By the way, a PNP output type multi-optical axis photoelectric switch has an input circuit corresponding to PNP output (hereinafter referred to as “PNP-compatible input circuit”), and an NPN output type multi-optical axis photoelectric switch has an input circuit compatible with NPN output ( Hereinafter, it is necessary to connect the “NPN-compatible input circuits”. Here, conventionally, since the signal input device connected to the multi-optical axis photoelectric switch has only one of the PNP-compatible input circuit and the NPN-compatible input circuit, the user side and the manufacturer side must It is inconvenient because it is necessary to prepare two types of signal input device corresponding to NPN and signal input device corresponding to NPN.

  The present invention has been completed based on the above situation, and has an input form capable of capturing an output signal from a PNP output device and an input capable of capturing an output signal from an NPN output device. An object of the present invention is to provide a signal input circuit and a relay unit circuit capable of automatically switching between forms.

  As means for achieving the above object, the invention of claim 1 is such that a PNP type output device and an NPN type output device can be selectively connected, and the PNP type output device is connected. A signal input circuit for capturing an output signal from the output device when the output device is connected, and an output signal from the output device when the NPN-type output device is connected; One signal input terminal, a second signal input terminal to which a signal is input from the outside, and the second signal input terminal are substantially the same as one of a high potential reference level and a low potential reference level having different levels. When the voltage is at the level, the voltage level of the first signal input terminal is set to the low potential reference level side so that the output signal from the PNP type output device can be input. Trust When the input terminal is substantially at the same level as the other of the high potential reference level and the low potential reference level, the voltage level of the first input terminal is set to the high potential reference level side and the NPN output And a selection circuit for performing a selection operation in a second input form capable of inputting an output signal from the apparatus.

  According to a second aspect of the present invention, in the first aspect, the voltage level of the second signal input terminal is within a predetermined range between the high potential reference level and the low potential reference level. In some cases, the first signal input terminal operates so as to select a third input mode in which neither the high potential reference level side nor the low potential reference level side is set.

  According to a third aspect of the present invention, in the first or second aspect, the one reference level is the low potential reference level, and the other reference level is the high potential reference level. And

According to a fourth aspect of the present invention, in the display device according to any one of the first to third aspects, the selection circuit is configured such that a potential difference between the high potential reference level and the voltage level of the second signal input terminal is not less than a predetermined value. A first mechanical relay circuit that closes a relay contact between the first signal input terminal and the signal line side of the low potential reference level on the condition that, the low potential reference level and the first potential A second operation of closing a relay contact between the first signal input terminal and the signal line side of the high potential reference level on condition that the potential difference with the voltage level of the two signal input terminals is a predetermined value or more. And a mechanical relay circuit.
The “predetermined value” may be different between the first mechanical relay circuit (for example, a configuration including a relay coil and a relay contact) and the second mechanical relay circuit.
Further, the selection circuit constituted by a semiconductor relay circuit is included in the inventions of claims 1 to 3.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the first signal input terminal includes a signal output line, a pair of power input lines, and the pair of power input lines. Is a signal input terminal connected to the signal output line among shielded electric wires connected to the output device, and having a shield member serving as either one of the pair of power input lines or a pair thereof. A pair of power supply terminals respectively connected to the power supply input lines, wherein the high potential reference level and the low potential reference level are respectively the voltage levels of the high potential terminal and the low potential terminal of the pair of power supply terminals. The second signal input terminal is a shielding terminal connected to the shield member.
That is, the configuration is as follows.
(Configuration A) “When a PNP output device and an NPN output device are selectively connectable, and the PNP output device is connected, an output signal from the output device is When an NPN type output device is connected, it is a signal input circuit that takes in an output signal from this output device,
A signal output line; a pair of power input lines; and a shield member that is separate from the pair of power input lines or serves as either one of the pair of power input lines, and is connected to the output device. Among the shielded wires, a signal input terminal connected to the signal output line,
A pair of power supply terminals respectively connected to the pair of power input lines;
A shielding terminal connected to the shielding member;
When the shielding terminal is at substantially the same voltage level as one of the pair of power supply terminals, the signal input terminal is connected to the low potential terminal side of the pair of power supply terminals. Thus, the shield terminal is at substantially the same voltage level as the other power supply terminal of the pair of power supply terminals, while the first input form is capable of inputting an output signal from the PNP output device. In some cases, the signal input terminal is connected to the high potential terminal side of the pair of power supply terminals, and the selection operation is performed to select the second input form in which the output signal from the NPN output device can be input. A signal input circuit comprising a circuit. "
In the present invention, the “shielded electric wire” may have a configuration in which any one of the power input lines is shared with the shield member in the shielded electric wire. Specifically, the shielded electric wire includes, for example, one power input line, a signal output line, and a braided shield (shield member) that surrounds them individually or collectively, and this braided shield is the other power input. The structure which serves also as a line may be sufficient. In this case, the braided shield is connected to the shield terminal of the signal input circuit on one end side connected to the signal input circuit side, while a part of the braided shield is pulled out to be one of the pair of power supply terminals. It will be connected to one side.

Moreover, the structure which added the structure D from the following structure B to the said structure A may be sufficient.
(Configuration B) “When the voltage level of the shielding terminal is within a predetermined range sandwiched between both voltage levels of the pair of power supply terminals, the selection circuit sets the signal input terminal to the low potential terminal side. And a signal input circuit according to Configuration A, wherein the signal input circuit operates so as to select a third input mode that is not connected to either of the high potential terminals. ”(Configuration included in Claim 2)
(Configuration C) “Signal input circuit according to Configuration A or Configuration B, wherein the one power supply terminal is a low potential side terminal and the other power supply terminal is a high potential side terminal.” Configuration included in claim 3)
(Configuration D) “The selection circuit includes
A first mechanical relay circuit that operates to close a relay contact between the signal input terminal and the low potential terminal side on condition that a potential difference between the high potential side terminal and the shield terminal is equal to or greater than a predetermined value; ,
A second mechanical relay circuit that operates to close a relay contact between the signal input terminal and the high potential terminal side on condition that a potential difference between the low potential side terminal and the shield terminal is equal to or greater than a predetermined value; The signal input circuit according to any one of configurations A to C, comprising: (Configuration included in claim 4)

In the present invention, the following configuration may be added.
That is, in the signal input circuit according to any one of the configurations A to D, when the voltage level of the shield terminal is close to the voltage level of the low potential side terminal, the low potential side terminal and the shield Short-circuit means for short-circuiting the high-potential side terminal and the shield terminal when the voltage level of the shield terminal is close to the voltage level of the high-potential side terminal while short-circuiting the terminal Configuration ".
More specifically, “the short-circuiting means includes the low-potential side terminal (the other power source) on the condition that the potential difference between the high-potential side terminal (the one power source terminal) and the shielding terminal is a predetermined value or more. Terminal) and the third relay circuit for short-circuiting between the shield terminal, and between the high potential side terminal and the shield terminal, provided that the potential difference between the low potential side terminal and the shield terminal is equal to or greater than a predetermined value. And a fourth relay circuit that short-circuits the circuit. "
With such a configuration, for example, when the signal input circuit and the output device are separated and connected via a long shielded wire, the shield terminal in the signal input circuit is connected to the low potential side terminal or the high potential side. A reliable shielding effect can be obtained by short-circuiting the terminals.
In this configuration, the “predetermined value” may be different between the third relay circuit and the fourth relay circuit. The relay circuit is not limited to a mechanical relay circuit (for example, a configuration including a relay coil and a relay contact), but may be a semiconductor relay circuit (for example, a configuration using a semiconductor element such as a switch element).

  A relay unit circuit according to a sixth aspect of the invention is incorporated in the signal input circuit according to any one of the first to fourth aspects, a pair of connection terminals to which an external device is connected, and the signal input circuit. And a relay circuit for connecting the pair of connection terminals based on the output signal.

  The invention according to claim 7 is the one according to claim 6, wherein the first signal input terminal is separated from the signal output line, the pair of power input lines, the pair of power input lines, or a pair of them. A shield member that also serves as one of the power input lines, and is a signal input terminal connected to the signal output line among the shielded wires connected to the output device, and is connected to the pair of power input lines, respectively. A pair of power supply terminals, wherein the high potential reference level and the low potential reference level are the voltage levels of the high potential terminal and the low potential terminal of the pair of power supply terminals, respectively, and the second signal input The terminal is a shielding terminal connected to the shield member.

  The invention according to an eighth aspect is the one according to the seventh aspect, wherein the PNP output device is a PNP output multi-optical axis photoelectric sensor, and the NPN output device is an NPN output multi-optical axis photoelectric sensor. It is characterized by being.

<Invention of Claim 1, Claim 3 to Claim 8>
Normally, if the output device is a PNP type (PNP output type), the shield member of the shielded wire can be short-circuited to the low potential side input line of the pair of power input lines and be NPN type (NPN output type). For example, it is short-circuited to the high potential side input line of the pair of power input lines. Therefore, based on the voltage level of the shield terminal connected to the shield member, the PNP input form (first input form) and the NPN input form (corresponding to the connected output device (PNP type, NPN type)) The second input mode can be automatically switched.
The signal input circuit according to the present application pays attention to this point. Specifically, the voltage level of the shielding terminal (second signal input terminal) is, for example, the voltage level of the low potential side terminal (low potential reference level). When it is near, the connected output device is a PNP type, and the signal input terminal (first signal input terminal) is connected to the low potential terminal side (to the low potential reference level side) to output the PNP type. It becomes the 1st input form into which the output signal from a device is inputted. On the other hand, when the voltage level of the shielding terminal (second signal input terminal) is close to the voltage level (high potential reference level) of the high potential side terminal, it is assumed that the connected output device is an NPN type, and the signal input terminal By connecting the (first signal input terminal) to the high potential terminal side (to the high potential reference level side), the output signal from the NPN output device is input.
According to such a configuration, only by connecting the output device, it is discriminated whether it is a PNP type or an NPN type, and the input mode is automatically switched between the PNP input and the NPN input accordingly. Therefore, it is not necessary to prepare two types of signal input devices compatible with PNP and signal input devices compatible with NPN on the user side and the manufacturer side, and for example, management costs can be reduced.

<Invention of Claim 2>
For example, for some reason, for example, when the shield terminal (second signal input terminal) of the signal input circuit is not connected to the shield member of the shield wire, the voltage level of the shield terminal becomes unstable and connected. It may be difficult to identify on the signal input circuit side whether the output device is a PNP type or an NPN type.
Therefore, according to this configuration, when the voltage level of the shield terminal is within a predetermined range between the voltage levels of the pair of power supply terminals, the signal input terminal is connected to the low potential terminal side and the high potential terminal side. It is set as the structure which is not connected to any (3rd input form).

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
The relay unit 50 of the present embodiment is selectively connectable to a PNP type (PNP output type) multi-optical axis photoelectric switch and an NPN type (NPN output type) multi-optical axis photoelectric switch. When the multi-optical axis photoelectric switch is connected, the PNP output signal from here is taken in, and when the NPN type multi-optical axis photoelectric switch is connected, the NPN output signal from here is taken in.
In the following description, the PNP type multi-optical axis photoelectric switch and the NPN type multi-optical axis photoelectric switch are collectively referred to as “multi-optical axis photoelectric switch 1”. The “PNP output photoelectric switch 2” and the latter will be referred to as “NPN output photoelectric switch 3”), respectively.

1. Configuration of multi-optical axis photoelectric switch (1) Overall configuration of multi-optical axis photoelectric switch The PNP output photoelectric switch 2 and the NPN output photoelectric switch 3 as output devices of the present invention are mainly different in the circuit configuration of the signal output circuit 30. Other configurations are common. Therefore, first, the common configuration will be described with reference to FIG.

(A) Overall Configuration The multi-optical axis photoelectric switch 1 includes a light projector 10 and a light receiver 20 that are arranged to face each other. Both of the light projecting / receiving devices 10 and 20 have, for example, a prismatic shape extending vertically, and a plurality of light projecting elements 11 are arranged in a line along the vertical direction on the surface of the light projecting device 10 facing the light receiving device 20. A plurality of light receiving elements 21 paired with the light projecting elements 11 are arranged in a line along the vertical direction on the surface of the light receiver 20 facing the light projecting element 10.
In addition, for example, 16 of these light projecting / receiving elements 11 and 21 are provided, for example, and the light projecting / receiving terminals 11 and 21 arranged in the same order in the vertical direction are normal counterparts. The light receiving signal output by each light receiving element 21 receiving light is received by the light receiving circuit 22 only when the light from the normal counterpart light projecting element 11 is received. An operation display unit 26 is provided on the upper surface of the light receiver 20. For example, the operation display unit 26 includes an LED as an indicator lamp.

(B) Electrical Configuration FIG. 1 shows an electrical configuration related to the multi-optical axis photoelectric switch 1 of the present embodiment. As shown in the figure, the projector 10 is provided with a projector circuit 14 in which the projector elements 11 are connected. The projector circuit 14 operates based on a predetermined clock pulse signal. A drive signal is sequentially given from the light projecting element 11 on the upper end side to the light projecting element 11 on the lower end side, and this operation is repeated at a high cycle. Thereby, an optical signal is sequentially emitted from the light projecting element 11 on the upper end side of the projector 10.
On the other hand, the light receiver 20 is provided with a light receiving circuit 22 connected to the light receiving element 21. The light receiving circuit 22 includes a plurality of switch elements 25. The output terminals of the respective light receiving elements 21 are electrically connected to one lead portion of the switch elements 25, and the lead portion is connected to the other, and the light receiving control circuit. Commonly connected to 24 signal input terminals.

  Further, the control terminal 25 </ b> A provided in each switch element 25 is electrically connected to the output terminal of the light reception control circuit 24 through the shift register 23. Each switch element 25 is always in an off state, and a drive signal is sequentially given from the light reception control circuit 24 to each switch element 25 via the shift register 23. Only the light reception signal of the continuous light receiving element 21 is taken into the light reception control circuit 24.

  Further, the light receiving control circuit 24 takes in the clock pulse signal from the light projecting circuit 14 via a line L1 connecting the light projecting / receiving devices 10 and 20, and this clock pulse signal (that is, the light projecting element 11 of each light projecting element 11) The predetermined switch element 25 is turned on in synchronization with the optical timing. Specifically, among the light projecting elements 11 arranged in the upper and lower rows, the light receiving elements 21 arranged in the same order as the light projecting elements 11 at the moment when the light projecting elements 11 of a predetermined order project an optical signal. Only the continuous switch element 25 is turned on. Thereby, only when each light receiving element 21 receives light from the normal counterpart light projecting element 11, the light reception signal output by the light receiving element 21 is taken into the light reception control circuit 24.

  The light reception control circuit 24 checks the magnitude relationship between the received reception signal and a predetermined reference voltage in synchronization with the timing at which the switch elements 25 are sequentially turned on / off. When all of the light reception signals sequentially taken into the light reception control circuit 24 exceed the reference voltage VC1, the operation display unit 26 is turned off, and any one light reception signal falls below the reference voltage VC1. For example, the operation display unit 26 is turned on, and an operation signal that is inverted depending on whether or not an object to be detected is detected is output to a signal output circuit described below.

(2) Configuration of Signal Output Circuit As described above, the circuit configuration of the signal output circuit 30 differs between the PNP output photoelectric switch 2 and the NPN output photoelectric switch 3. The circuit configurations of the signal output circuits 31 and 41 of the PNP output photoelectric switch 2 and the NPN output photoelectric switch 3 are shown on the left side of FIG.

(A) Signal output circuit of PNP output photoelectric switch The signal output circuit 31 includes a PNP transistor 32 that receives the operation signal from the light receiving control circuit 24 as a base. Specifically, the signal output circuit 31 has a shield wire 33 led out from the output side. This shielded wire 33 is for connecting the signal output circuit 31 and a relay unit 50 to be described later. The Vcc terminal 52 and the ground terminal 53 on the relay unit 50 side (“one pair of power supply terminals” of the present invention). ), A signal output line 36 electrically connected to the signal input terminal 54 on the relay unit 50 side, and a shield member 37 (for example, a braided shield) surrounding these lines. And is configured. The PNP transistor 32 has a collector side electrically connected to a high potential side input line 34 electrically connected to a Vcc terminal 52 on the relay unit 50 side via a resistor 38, and an emitter connected to a signal output line. 36 is electrically connected. The shield member 37 is short-circuited to the low potential side input line 35 that is electrically connected to the ground terminal 53 on the relay unit 50 side.

(B) Signal output circuit of NPN output photoelectric switch The signal output circuit 41 includes an NPN transistor 42 that receives the operation signal from the light receiving control circuit 24 as a base. Specifically, in the signal output circuit 41, the shielded electric wire 43 is derived from the output side. The shielded electric wire 43 is for connecting the signal output circuit 41 and a relay unit 50 to be described later, and a pair of power input lines 44 and 45 connected to the Vcc terminal 52 and the ground terminal 53 on the relay unit 50 side. The signal output line 46 is electrically connected to the signal input terminal 54 on the relay unit 50 side, and a shield member 47 (for example, a braided shield) surrounding the lines. The NPN transistor 42 has a collector side electrically connected to the signal output line 46 and an emitter connected to the low potential side input line 45 connected to the ground terminal 53 on the relay unit 50 side. It is electrically connected via. The shield member 47 is short-circuited to the high potential side input line 44 that is electrically connected to the Vcc terminal 52 on the relay unit 50 side.

2. Here, as described above, generally, the PNP type signal output circuit 31 has its shield member 37 short-circuited to the low potential side input line 35, and the NPN type signal output circuit 41 The shield member 47 is short-circuited to the high potential side input line 44. Therefore, it is possible to identify whether the connected signal output circuit is a PNP type or an NPN type based on the voltage level of the shield members 37 and 47 of the shielded wires 33 and 43 in a state where the signal output circuits 31 and 41 are connected. it can. Therefore, the present embodiment has the following configuration.
The relay unit 50 includes a signal input circuit 51 that captures an output signal from the multi-optical axis photoelectric switch 1, a pair of connection terminals 64 and 65 to which an external device is connected, and an output signal that is captured by the signal input circuit. And a relay circuit that electrically connects the connection terminal pair.

  Specifically, as shown on the right side of FIG. 2, the signal input circuit of the relay unit 50 includes a Vcc terminal 52 and a ground terminal 53 (“one pair of power supply terminals” of the present invention), a signal input terminal 54, and the like. And a shielding terminal 55. The Vcc terminal 52 and the ground terminal 53 are electrically connected to the high potential side input lines 34 and 44 and the low potential side input lines 35 and 45 of the shielded wires 33 and 43 connected to the signal output circuits 31 and 41, respectively. This is a terminal for supplying power from the power source 56 (for example, 24 V) to the optical axis photoelectric switch 1. The signal input terminal 54 is a terminal electrically connected to the signal output lines 36 and 46 of the shielded wires 33 and 43, and the shield terminal is electrically connected to the shield members 37 and 47 of the shielded wires 33 and 43. Terminal.

  Two relay coils 57 and 58 are connected in series between the Vcc terminal 52 and the ground terminal 53, and the connection point of these relay coils 57 and 58 is connected to the shield terminal 55. Next, between the signal input terminal 54 and the ground terminal 53, a pair of relay contacts 59 and 60 that are turned on by the magnetic force generated in the relay coil 57 are connected in series. That is, the relay coil 57 and the pair of relay contacts 59 and 60 correspond to the “first mechanical relay circuit” of the present invention. Hereinafter, it is referred to as a “PNP relay circuit”.

  Further, between the signal input terminal 54 and the Vcc terminal 52, a pair of relay contacts 61 and 62 that are turned on / off (open / close operation) by the magnetic force generated in the relay coil 58 are connected in series. That is, the relay coil 58 and the pair of relay contacts 61 and 62 correspond to the “second mechanical relay circuit” of the present invention. Hereinafter, it is referred to as “NPN relay circuit”. The first and second mechanical relay circuits constitute a “selection circuit” of the present invention.

  Further, the connection point between the pair of relay contacts 59 and 60 and the connection point between the relay contacts 61 and 62 are commonly connected via the relay coil 63 constituting the “relay circuit” according to claim 5. Yes. The relay unit 50 is provided with two connection terminal pairs 64, 65, and the connection terminal pairs 64, 65 are connected to the relay contacts 66, which are turned on / off (open / close operation) by the magnetic force generated in the relay coil 63. 67 is connected.

3. Operation of this embodiment (1) When a PNP output photoelectric switch is connected to the relay unit In this case, the shield member 37 of the shielded electric wire 33 is short-circuited to the 0 V low potential side input line 35 in the PNP output photoelectric switch 2. Therefore, the shield terminal 55 connected to the relay terminal is also at approximately 0V, and a voltage of approximately 24V is applied to the relay coil 57 of the PNP relay circuit. Is turned on (closed), and the signal input terminal 54 is electrically connected to the ground terminal 53 side. Thereby, the signal input circuit becomes a PNP input form (first input form) capable of inputting the PNP output signal from the PNP output photoelectric switch 2.

  At this time, different voltages are applied to the relay coil 63 depending on whether the PNP transistor 32 of the signal output circuit 31 on the PNP output photoelectric switch 2 side is on or off. In the present embodiment, for example, when the PNP transistor 32 is turned off by an operation signal when an object to be detected is not detected, the relay contacts 66 and 67 are turned on (closed) by the magnetic force generated in the relay coil 63. It is configured. Therefore, the relay unit 50 has the connection terminal pairs 64 and 65 interposed in a power supply line of a machine tool or the like as an external device to be controlled, and when no object to be detected is detected, While the machine tool is driven by turning on 67, the relay contacts 66 and 67 are turned off to stop the machine tool when an object to be detected is detected.

(2) When an NPN output photoelectric switch is connected to the relay unit In this case, since the shield member 47 of the shielded electric wire 43 is short-circuited to the high potential side input line 44 of 24 V in the NPN output photoelectric switch 3, it is connected to this. The shield terminal 55 is also approximately 24V, and a voltage of approximately 24V is applied to the relay coil 58 of the NPN relay circuit, and the relay contacts 61 and 62 are turned on (closed) by the magnetic force generated thereby. The signal input terminal 54 is electrically connected to the Vcc terminal 52 side. Thereby, the signal input circuit becomes an NPN input form (second input form) capable of inputting the NPN output signal from the NPN output photoelectric switch 3.

  At this time, different voltages are applied to the relay coil 63 depending on whether the NPN transistor 42 of the signal output circuit 41 on the NPN output photoelectric switch 3 side is on or off. In the present embodiment, for example, when the NPN transistor 42 is turned off by an operation signal when an object to be detected is not detected, the relay contacts 66 and 67 are turned on (closed operation) by the magnetic force generated in the relay coil 63. It is configured. Therefore, the relay unit 50 also has its connection terminal pairs 64 and 65 interposed in a power supply line of a machine tool or the like as an external device to be controlled, and when no object to be detected is detected, the relay contact 50 While the machine tool is driven by turning on 66 and 67, the relay contacts 66 and 67 are turned off to stop the machine tool when an object to be detected is detected.

4). As described above, according to the present embodiment, when the multi-optical axis photoelectric switch 1 is connected, the multi-optical axis photoelectric switch 1 is connected to the PNP output photoelectric switch 2 based on the voltage level of the shielding terminal 55. Or an NPN output photoelectric switch 3 and automatically switches to an input form (PNP input, NPN input) corresponding to the switch. Therefore, it is possible to deal with both the PNP output photoelectric switch 2 and the NPN output photoelectric switch 3 by preparing only one relay unit 50 of the present embodiment.

  In the present embodiment, the relay contacts 59 and 60 and the relay contacts 61 and 62 are turned on by the relay coil 57 or the relay coil 58 only when the voltage level of the shield terminal 55 is approximately 24 V or 0 V, respectively. , The relay contacts 59 to 62 are not turned on when the level is lower than 24V by a predetermined value and higher than the predetermined value by 0V (third input form). Accordingly, it is possible to prevent the output signal from the multi-optical axis photoelectric switch 1 from being input in a state where it cannot be identified whether the multi-optical axis photoelectric switch 1 is a PNP output or an NPN output due to some influence. At this time, since no voltage is applied to the relay coil 63 and the relay contacts 66 and 67 are not turned on, it is possible to prevent erroneous control of an external device such as a machine tool.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In each of the above embodiments, the multi-optical axis photoelectric switch 1 has been described as an example of an output device. However, the present invention is not limited to this, and in short, any output device that outputs a PNP output signal or an NPN output signal. The present invention can be applied to.

  (2) In the above embodiment, the signal output circuits 31 and 41 are configured as output circuits using bipolar transistors of the open collector circuit of the PNP type transistor 32 and the NPN type transistor 42. However, the present invention is not limited to this, and PchFET and NchFET May be an output circuit.

The circuit block diagram of the multi-optical axis photoelectric switch of one Embodiment of this invention Circuit configuration diagram of signal output circuit and relay unit circuit of multi-optical axis photoelectric switch

Explanation of symbols

1. Multi-optical axis photoelectric switch (output device)
2. PNP output photoelectric switch (PNP output device)
3 ... NPN output photoelectric switch (NPN output device)
30 (31, 41) ... signal output circuit 33, 43 ... shielded wire 34, 44 ... high potential side input line (power input line)
35, 45 ... low potential side input line (power input line)
36, 46 ... Signal output line 37, 47 ... Shield member 50 ... Relay unit 51 ... Signal input circuit 52 ... Vcc terminal (high potential side terminal)
53 ... Ground terminal (low potential side terminal)
54 ... Signal input terminal 55 ... Shielding terminal 57, 58, 63 ... Relay coil 58 ... Relay coil 59, 60 ... Relay contact 59-62, 66, 67 ... Relay contact

Claims (8)

A PNP-type output device and an NPN-type output device can be selectively connected. When the PNP-type output device is connected, an output signal from the output device is sent to the NPN-type output device. Is a signal input circuit that takes in an output signal from this output device when connected,
A first signal input terminal to which the output signal is input;
A second signal input terminal to which a signal is input from the outside;
When the second signal input terminal is at substantially the same level as one of a high potential reference level and a low potential reference level having different levels, the voltage level of the first signal input terminal is set to the low potential reference. On the level side, the first input form is configured such that an output signal from the PNP type output device can be input, while the second signal input terminal is the other reference level of the high potential reference level and the low potential reference level. When the voltage level of the first input terminal is set to the high potential reference level side, the selection operation is performed so that the output signal from the NPN-type output device can be input. A signal input circuit comprising a selection circuit. The selection circuit sets the voltage level of the first signal input terminal to the high potential reference when the voltage level of the second signal input terminal is within a predetermined range between the high potential reference level and the low potential reference level. 2. The signal input circuit according to claim 1, wherein the signal input circuit operates so as to select a third input mode which is not set on either the level side or the low potential reference level side. 3. The signal input circuit according to claim 1, wherein the one reference level is the low potential reference level, and the other reference level is the high potential reference level. The selection circuit includes:
A relay contact between the first signal input terminal and the signal line side of the low potential reference level on condition that a potential difference between the high potential reference level and the voltage level of the second signal input terminal is a predetermined value or more. A first mechanical relay circuit that operates to close
A relay contact between the first signal input terminal and the signal line side of the high potential reference level on condition that a potential difference between the low potential reference level and the voltage level of the second signal input terminal is equal to or greater than a predetermined value. 4. The signal input circuit according to claim 1, further comprising a second mechanical relay circuit that performs an operation of closing the first and second relay circuits. The first signal input terminal includes a signal output line, a pair of power input lines, a shield member that is separate from the pair of power input lines or serves as either one of the pair of power input lines. Of the shielded electric wires connected to the output device, the signal input terminal connected to the signal output line,
A pair of power supply terminals connected to the pair of power supply input lines, respectively, wherein the high potential reference level and the low potential reference level are respectively the high potential terminal and the low potential terminal of the pair of power supply terminals; Voltage level of
5. The signal input circuit according to claim 1, wherein the second signal input terminal is a shield terminal connected to the shield member. 6. A signal input circuit according to any one of claims 1 to 4;
A pair of connection terminals to which external devices are connected;
A relay unit circuit comprising: a relay circuit that connects the pair of connection terminals based on the output signal captured by the signal input circuit. The first signal input terminal includes a signal output line, a pair of power input lines, a shield member that is separate from the pair of power input lines or serves as either one of the pair of power input lines. Of the shielded electric wires connected to the output device, the signal input terminal connected to the signal output line,
A pair of power supply terminals connected to the pair of power supply input lines, respectively, wherein the high potential reference level and the low potential reference level are respectively the high potential terminal and the low potential terminal of the pair of power supply terminals; Voltage level of
The relay unit circuit according to claim 6, wherein the second signal input terminal is a shielding terminal connected to the shield member. 8. The relay unit circuit according to claim 7, wherein the PNP output device is a PNP output multi-optical axis photoelectric sensor, and the NPN output device is an NPN output multi-optical axis photoelectric sensor.

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