JPH1098369A - Photoelectric switch and its integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric switch and its integrated circuit, whereby a photoelectric switch integrated circuit and a photoelectric switch can be made to be small. SOLUTION: An integrated circuit IC is provided with an output terminal T4, capable of connecting an NPN-type output transistor and the output terminal T3 capable of connecting an PNP-type output transistor. Further, an operation display light 92 for displaying that the photoelectric switch is operating, based on the potential of one of the output terminals of T4 or T3, is not connected to the output transistor, is connected to the output terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric switch and an integrated circuit for use in applications such as object detection, and more particularly, to a photoelectric switch having a first conductivity type or a second conductivity type output transistor. A photoelectric switch capable of generating a detection output by operating an output transistor, and supplying a potential to an output transistor of a first conductivity type or a second conductivity type to generate a detection output by operation of the output transistor The present invention relates to an integrated circuit for a photoelectric switch that can supply a potential to an operation notifying unit for notifying that a detection operation is being performed and execute the notification.

[0002]

2. Description of the Related Art A photoelectric switch is conventionally used as a device for detecting the presence or absence of an object in a predetermined area. For example, such a photoelectric switch is provided at a predetermined position of a work device such as a press device that performs a predetermined operation, and is used to detect whether an object such as a human has entered a predetermined region. I have.

[0003] Generally, such a photoelectric switch is provided with a dedicated integrated circuit for downsizing the switch.
An output transistor including a bipolar transistor for outputting a detection signal is externally connected to a semiconductor chip of such a dedicated integrated circuit. For example, a PNP type is mainly used in Europe,
In the United States and Japan, the NPN type tends to be mainly used. That is, the conductivity type of the output transistor connected to the outside is different for each country where the device is used.

[0004] For this reason, an integrated circuit dedicated to the photoelectric switch selectively mounts output transistors of both NPN type and PNP type in order to reduce the number of integrated circuits and to improve versatility. It has a possible configuration. In addition, an operation indicator light that is turned on when an object is detected is connected to the integrated circuit dedicated to the photoelectric switch.

Hereinafter, a specific example of the conventional photoelectric switch will be described. FIG. 10 is a circuit diagram showing a connection mode between an output transistor and an operation indicator in a conventional photoelectric switch to which an NPN output transistor is attached. FIG.
Referring to FIG. 0, the photoelectric switch includes an integrated circuit IC1 for the photoelectric switch, and external components such as an output transistor 61, a resistance element 62, and an operation indicator 92 externally connected to the integrated circuit IC1. ing. In addition,
Although external components are provided in addition to those components, description thereof is omitted here.

The integrated circuit IC1 has power terminals T1, T2,
Input terminals T10 to T14 and output terminals T3, T
It has a number of input pins and output pins, such as 4, T5, T7. The power supply terminals T1 and T2 are terminals for receiving supply of a power supply voltage. The output terminal T3 is a detection output terminal when the PNP transistor is provided as an output transistor. The output terminal T4 is a terminal for detection output when the NPN transistor is provided as an output transistor.

An output transistor 61 and a resistance element 62 are connected in series between an output terminal T23 provided outside the integrated circuit IC1 and a ground node GND receiving a ground potential. The output transistor 61 has a base connected to the output terminal T4. The output terminal T7 is a terminal for outputting an internal power supply voltage. The output terminal T11 is
This is a terminal to which an operation indicator light 92 made of a light emitting diode is connected, and the operation indicator light 92 is connected between the output terminal T11 and the input terminal T9. The output terminal T5 is
A terminal for outputting a signal for driving a light emitting element (not shown) mounted outside the integrated circuit IC1.

When a PNP type output transistor is mounted, the output transistor is connected to the output terminal T3. The input terminal T10 is a terminal to which a stability indicator (not shown) that is turned on when the amount of light received by the photoelectric switch is stable is connected. The input terminal T12 has an operation mode of outputting a detection output indicating that an object has been detected when a light receiving element (not shown) of the photoelectric switch receives light, and an operation mode in which light received by the light receiving element is blocked. L / for switching an operation mode for outputting a detection signal indicating that an object has been detected
A terminal to which a D changeover switch (not shown) is connected.

The input terminal T13 is a terminal to which a signal for changing the detection cycle of the photoelectric switch is input. The input terminal T14 is a terminal to which a signal for adjusting the detection sensitivity of the photoelectric switch is input. The detailed configuration of such a photoelectric switch will be described later.

As described above, the one of the output terminals T3 and T4 to which the output transistor is not connected receives the power supply potential or the ground potential according to the conductivity type of the output transistor to be connected. That is, in the integrated circuit IC1, of the potential terminals T3 and T4, the terminal to which the output transistor is not connected has not been used particularly for attaching external parts. In order to mount the operation indicator light 92, the integrated circuit IC1 is provided with an input terminal T11 dedicated to the operation indicator light.

Next, a detailed configuration of the conventional photoelectric switch shown in FIG. 10 will be described. FIG. 11 is a block diagram showing a detailed configuration of a conventional photoelectric switch. FIG.
Referring to FIG. 1, this photoelectric switch is connected to a semiconductor chip CH.
It includes an integrated circuit IC1 for a photoelectric switch formed thereon and an external circuit externally connected to the semiconductor chip CH.

The integrated circuit IC1 comprises a constant voltage circuit 1, a power supply reset circuit 2, an output processing circuit 30, an oscillation circuit 4, an LED
Drive circuit 5, amplification circuit 6, comparator 7, signal processing circuit 8a, mutual interference prevention circuit 9, timer 10, and L
/ D switching circuit 11 is included. The output processing circuit 30 includes an output circuit 31, a short-circuit detection circuit 32a, and an output inhibition circuit 33.
including. Further, the integrated circuit IC1 has power supply terminals T1 and T2 formed as input / output pins and input terminals T8 to T8.
T12 and output terminals T1 to T7 are included.

The external circuits include a power supply circuit 50, a detection output circuit 60, a light emitting circuit 70, a light receiving circuit 80, a display circuit 90,
L / D switch SW, capacitor C1 and capacitor C2 are included. The power supply circuit 50 includes a noise filter circuit 51 and an external power supply circuit 52. The detection output circuit 60 includes an NPN type output transistor 61 and a resistance element 6
2 and a diode 63. The light projecting circuit 70 includes a light emitting diode 71, an NPN transistor 71, and a resistor 73. The light receiving circuit 80 includes a photodiode (FDi) 81 and an I / V conversion amplifier circuit 82. The display circuit 90 includes a stability indicator light 91 and an operation indicator light 9.
2 and a capacitor 93.

Next, the operation of the photoelectric switch having such a configuration will be described. Power supply terminal T21 receiving power supply potential Vcc
And an external power supply voltage is supplied to the noise filter circuit 51 from a ground terminal T22 connected to the ground node GND and receiving the ground potential Vg. The noise filter circuit 51 removes noise from the external power supply voltage and supplies the external power supply voltage from which the noise has been removed to the external power supply circuit 52. The external power supply circuit 52 converts the supplied external power supply voltage to a predetermined voltage, and converts the converted power supply voltage to the power supply terminals T1 and NPN.
Supply terminal T3.

The integrated circuit IC1 receives a ground potential from a ground node GND via a power supply terminal T2. This ground potential is supplied to each circuit in the photoelectric switch integrated circuit IC1. The constant voltage circuit 1 receives a power supply potential from an external power supply circuit 52 via a power supply terminal T1, and generates an internal power supply voltage that is a predetermined constant voltage. The internal power supply voltage is supplied to each circuit in the integrated circuit IC1 and used for the operation of each circuit.

The oscillating circuit 4 oscillates a pulse signal of a predetermined cycle, and supplies the pulse signal to each of the LED drive circuit 5 and the signal processing circuit 8a. The LED drive circuit 5 synchronizes with the pulse signal received from the oscillation circuit 4 to emit light from the light emitting diode 71,
An H-level potential for operating the transistor 72 is supplied to the base of the transistor 72 via the output terminal T5. A base current flows through the transistor 72 according to the potential.

In the light emitting circuit 70, the power supply potential Vcc
A light emitting diode 71, a transistor 72, and a resistance element 73 are connected in series between a power supply node N1 receiving the power supply node N1 and a ground node GND. Transistor 72
Has a collector connected to the cathode of the light emitting diode 71 and an emitter connected to one end of the resistance element 73. When the transistor 72 receives an H-level potential from the LED drive circuit 5, a base current flows, and a collector current flows according to the base current. Accordingly, the transistor 72 is turned on, a current flows through the light emitting diode 71, and the light emitting diode 71 is turned on. Since an H-level potential is supplied to the base of the transistor 72 in a cycle synchronized with a pulse signal oscillated from the oscillation circuit 4, the light emitting diode 71 is turned on in a cycle synchronized with the pulse signal, and light is emitted. It is.

In this photoelectric switch, the light emitting diode 7
When the light projected from 1 is reflected by a detection target such as an object, the reflected light is received by the photodiode 81.
When receiving light, the photodiode 81 generates a current by photoelectric conversion. The current is voltage-converted by the I / V conversion amplifier circuit 82, and the voltage is amplified. The I / V conversion amplification circuit 82 includes a photodiode 81
Is supplied to the amplifier circuit 6 via the capacitor C1 and the input terminal T8.

The amplification circuit 6 amplifies the supplied light receiving signal and outputs the amplified light receiving signal. The amplified light receiving signal is supplied to the comparator 7 via the output terminal T6, the capacitor C2, and the input terminal T9 sequentially. The comparator 7 compares the level of the supplied light receiving signal with a predetermined reference level, and supplies only a light receiving signal having a level equal to or higher than the reference level to the signal processing circuit 8.

The signal processing circuit 8a takes in the signal from the comparator 7 in synchronization with the pulse signal supplied from the oscillation circuit 4. Thus, the light emitting operation and the light receiving operation are performed in synchronization. The signal processing circuit 8a is a circuit that performs predetermined signal processing. The processing performed by the signal processing circuit 8a includes signal processing for operating each of the stability indicator lamp 91 and the operation indicator lamp 92, and light processing between the photoelectric switch and another photoelectric switch provided alongside the photoelectric switch. Signal processing for preventing mutual interference and signal processing for outputting a detection signal indicating that the photoelectric switch has detected an object are included.

First, the stability indicator 91 and the operation indicator 9
Signal processing for operating each of the two will be described. Each of the stability indicator light 91 and the operation indicator light 92
It consists of light emitting diodes. The internal power supply voltage is supplied from the constant voltage circuit 1 to the anodes of the stability indicator lamp 91 and the operation indicator lamp 92 via the output terminal T7. A capacitor 93 is provided in the supply path of the internal power supply voltage, and the charge accumulated in the capacitor 93 stabilizes the lighting state of the stability indicator lamp 91 and the operation indicator lamp 92. The cathode of the stability indicator 91 is connected to the input terminal T
10 is connected to the signal processing circuit 8a. The cathode of the operation indicator lamp 92 is connected to the signal processing circuit 8a via the input terminal T11.

The signal processing circuit 8a converts the potential of the cathode of each of the stability indicator lamp 91 and the operation indicator lamp 92 to the ground potential V
By performing the operation of descending toward g, each of the stability indicator lamp 91 and the operation indicator lamp 92 can be turned on. In the signal processing circuit 8a, the comparator 7
When the level of the light receiving signal supplied from the controller is equal to or higher than a predetermined level, the stability indicator 91 is turned on to indicate that light is received with a stable light receiving amount. Further, in the signal processing circuit 8a, when the light receiving signal is supplied from the comparator 7 continuously for a predetermined number of times, the operation indicator lamp 92 is turned on to indicate that an object has been detected. Thereby, when an object is detected, the operation indicator lamp 92 is turned on.

Next, signal processing for preventing mutual interference of light with another photoelectric switch provided side by side with the photoelectric switch will be described. The signal processing circuit 8a is provided to prevent mutual interference of light with another photoelectric switch.
A predetermined control signal is supplied to the mutual interference prevention circuit 9. In the mutual interference prevention circuit 9, in response to the supplied control signal,
A control signal for adjusting the oscillation cycle of the pulse signal of the oscillation circuit 4 is supplied to the oscillation circuit 4 in order to prevent mutual interference of light. The oscillation circuit 4 adjusts the oscillation cycle of the pulse signal according to the mutual interference prevention circuit 9.

Next, signal processing for outputting a detection signal indicating that the photoelectric switch has detected an object will be described. The signal processing circuit 8a supplies a signal to the output circuit 31 in order to output a detection signal indicating that an object has been detected when the light receiving signal is supplied from the comparator 7 continuously for a predetermined number of times.

The output circuit 31 is a circuit for performing an operation for outputting a detection signal indicating that an object has been detected. The output circuit 31 can output a signal for operating the NPN output transistor 61 via the NPN output terminal T4, and outputs a signal for operating the PNP output transistor to the PNP output transistor T4. It is possible to output via the output terminal T3. Output circuit 3
1 operates as a power reset circuit 2 or an output inhibit circuit 3
3 may be banned. The power supply reset circuit 2 receives the internal power supply voltage from the constant voltage circuit 1, and outputs a signal for inhibiting the operation of the output circuit 31 until the voltage value of the internal power supply voltage reaches a stable level after the power supply of the photoelectric switch is turned on. Supply to circuit 31.

The short-circuit detection circuit 32a includes an output transistor (output transistor 61) connected to the integrated circuit IC1.
Is detected that the load connected to is short-circuited and an excessive short-circuit current flows through its output transistor. When the short-circuit current is detected by the short-circuit detection circuit 32a,
The output inhibition circuit 33 is operated, and as a result, the operation of the output circuit 31 is inhibited. The prohibition of such an operation is performed to prevent the output transistor 61 and the integrated circuit IC1 from being damaged by an excessive short-circuit current. The period during which the operation of the output circuit 31 is inhibited by the output inhibition circuit 33 is defined by the timer 10.

The L / D switch SW is a switch for switching the operation mode of the photoelectric switch. This photoelectric switch has an operation mode (D mode) for outputting a detection signal indicating that an object has been detected when it detects that the object has blocked light, and an object mode for detecting that the object has reflected light. There are two types of operation modes: an operation mode (L mode) for outputting a detection signal indicating that the signal has been detected.
This L / D switch SW is operated by a switch operation.
This is for switching between these two types of operation modes. The L / D switch SW has an input terminal T12,
It is connected between the ground node GND. Input terminal T
The L / D switching circuit 11 is connected to the L / D switch 12.
The D switching circuit 11 outputs a signal for switching an operation mode according to the operation state of the L / D switch SW to the output circuit 3.
Supply to 1. Output circuit 31 performs an output operation of the detection signal in an operation mode corresponding to the signal supplied from L / D switching circuit 11.

The output transistor 61 has an NPN base.
Output terminal T4, and the collector is connected to the output terminal T2.
3 and the emitter is connected to the ground node GND via the resistance element 62. A diode 63 for absorbing surge current is connected between the output terminal T23 and the ground node GND. The output terminal T23 is connected to a predetermined load (not shown).

The operation of the output circuit 31 causes the output terminal T4
, An H level potential is supplied to the base of the output transistor 61. In response, the output transistor 6
1, a base current flows, and a collector current flows through the output transistor 61 in response to the base current. As a result, the output transistor 61 is turned on, and a detection signal indicating that the photoelectric switch has detected an object is output to the load.

Next, in the integrated circuit IC1, the configuration of a portion related to the respective operations of the externally mounted operation indicator lamp 92 and the output transistor 61 will be described in detail.

First, the internal configuration of the integrated circuit IC1 related to the operation of the operation indicator lamp 92 will be described. FIG. 12 is a circuit diagram showing the internal configuration of the integrated circuit IC1 related to the operation of the operation indicator lamp 92. Referring to FIG.
In C1, the operation indicator lamp 9 in the signal processing circuit 8a.
2 is included.

The operation indicator light driving circuit 800 includes a constant current source 8
01, a resistance element 802, and three NPN transistors 803 to 805. When the signal processing circuit 8 does not continuously receive the detection signal a predetermined number of times from the comparator 7, the potential of the signal S supplied to the base of the transistor 803 becomes L level. Therefore, in that case, transistor 803 is turned off, so that all the current generated from constant current source 801 is applied to resistance element 802.
Flows to In resistor element 802, a potential drop occurs in accordance with the flowing current, and the dropped potential is supplied to the bases of transistors 804 and 805. In that case, the range of potential drop due to the resistance element 802 is large, so that the transistors 804 and 805 are not turned on. Therefore, in that case, the operation indicator 92
Does not light.

On the other hand, from the comparator 7 to the signal processing circuit 8
And the detection signal is supplied a predetermined number of times consecutively, the signal S goes high and the transistor 803 is turned on. Thus, most of the current from the constant current source 801 flows to the transistor 803. Thereby, the resistance element 8
02 decreases, the level of the potential supplied to the base of each of the transistors 804 and 805 increases, and the transistors 804 and 805 are turned on. When the transistor 805 is turned on, the operation indicator 92 lights.

Next, the internal configuration of the integrated circuit IC1 related to the operation of the output transistor 61 will be described. FIG.
Is an integrated circuit I related to the operation of the output transistor 61.
FIG. 3 is a circuit diagram showing an internal configuration of C1.

Referring to FIG. 13, a load L is connected between a power supply terminal T21 and an output terminal T23. The output circuit 31 includes three NPN transistors 311 and 31
2,313. The bases of the transistor 312 and the transistor 313 are connected to each other.
The emitters are connected. Each of transistors 312 and 313 has a base connected to the emitter of transistor 311 and an emitter connected to output terminal T4. The collector of the transistor 313 is connected to the output terminal T3. Transistor 31
Reference numeral 1 denotes a collector connected to the power supply terminal T1. The base of transistor 311 and the collector of transistor 312 receive signal S1 output from signal processing circuit 8 via output inhibition circuit 33. This signal S1 is a signal that goes high when the signal processing circuit 8 receives the detection signal from the comparator 7 a predetermined number of times in succession, and indicates that an object has been detected.

The short-circuit detection circuit 32a includes a PNP-side detection circuit 321, an NPN-side detection circuit 322, and an OR circuit 324.
including. The PNP-side detection circuit 321 is a circuit for detecting that a short-circuit current has flowed in the output transistor connected to the PNP output terminal T3, and includes a power supply terminal T1,
It is connected between the output terminal T3. The detection signal of the PNP side detection circuit 321 is supplied to one input terminal of the OR circuit 324.

The NPN side detection circuit 322 is a circuit for detecting a short-circuit current flowing through the output transistor 61 connected to the NPN output terminal T4, and is connected between the output terminal T4 and the power supply terminal T2. NPN side detection circuit 322
Is supplied to the other input terminal of the OR circuit 323. The output signal of the OR circuit 323 is supplied from an output terminal to the output inhibition circuit 33. The output inhibit circuit 33
When the output signal of the R circuit 323 becomes H level, the supply of the signal S1 output from the signal processing circuit 8 to the output circuit 31 is prohibited.

Next, the operation of the circuit shown in FIG. 13 will be described. The NPN-side detection circuit 322 detects a voltage between the output terminal T4 and the power supply terminal T2, and outputs an H-level signal to the OR circuit 324 when the detected voltage value exceeds a predetermined threshold voltage. To supply. That is, as shown in FIG. 13, when load L is short-circuited and short-circuit current Ia flows through the transistor, transistor 61 and resistor 62
Output terminal T4 and power supply terminal T2
Is higher than the threshold voltage. Therefore, when the voltage between the output terminal T4 and the power supply terminal T2 becomes equal to or higher than the threshold voltage, the short-circuit current is reduced to the output transistor 61.
And the output signal is set to the H level.

The PNP side detection circuit 321 is connected to a power supply terminal T1.
And a voltage between the output terminal T3 and the output terminal T3. When the detected voltage value becomes equal to or lower than a predetermined threshold voltage, an H-level signal is supplied to the OR circuit 324. That is, PNP
When the PNP type output transistor is connected to the output terminal T3, the side detection circuit 321 detects the voltage between the power supply terminal T1 and the output terminal T3 by a threshold voltage due to an excessive short-circuit current flowing through the output transistor due to short-circuit of the load. When the voltage falls below the voltage, it is determined that the short-circuit current has flowed to the output transistor, and the output signal is set to the H level. In this case, since the PNP output transistor is not mounted and the output terminal T3 receives the power supply potential, the PNP side detection circuit 321 does not detect that the short-circuit current has flowed.

When the NPN side detection circuit 322 does not detect the short-circuit current, the output signal of the OR circuit 323 becomes L level. In that case, the output prohibition circuit 33 supplies the signal S1 to the output circuit 31 as it is. In this case, in the output circuit 31, the transistor 311 is connected to the base of the signal S.
It is turned on in response to the potential of 1. Transistor 311
Are turned on, transistors 312 and 313
In response to this, the transistors 312 and 313 are both turned on.
In that case, the transistor 313 is turned on, so that the potential of the output terminal T4 becomes H level. In response, the transistor 61 is turned on, and a signal indicating that the photoelectric switch has detected an object is output.

On the other hand, when the NPN-side detection circuit 322 detects a short-circuit current and an H-level signal is supplied to the OR circuit 323, the output signal of the OR circuit 323 becomes H-level. In that case, the output prohibition circuit 33 is
The supply of the signal S1 to the controller is prohibited. In that case, transistor 311 is turned off, and accordingly, transistors 312 and 313 are both turned off. When the transistor 313 is turned off, the potential of the output terminal T4 becomes L level. In that case, the output transistor 61 is turned off, and no detection signal indicating that the photoelectric switch has detected an object is output.

FIG. 13 shows an example in which an NPN type output transistor is provided as an output transistor. However, when a PNP type output transistor is provided, a ground potential is supplied to the output terminal T3. In that case, the NPN side detection circuit 342 cannot detect the short-circuit current, and the NPN side detection circuit 342 always keeps the output signal at the L level. Therefore, in that case, only the PNP-side detection circuit 321 detects the short-circuit current.

As described above, in the conventional photoelectric switch, in the integrated circuit IC1 of the photoelectric switch, the output terminal T3 for the PNP type output transistor is used.
And an output terminal T4 for an NPN-type output transistor.
Both N-type output transistors and N-type output transistors can be mounted. Further, a dedicated input terminal T11 of the operation indicator light 92 and the operation indicator light drive circuit 800 which light up when a detection signal is output from such an output transistor are provided.

[0044]

However, the above-mentioned conventional photoelectric switch has the following problems.

In the conventional photoelectric switch, the operation indicator 92
And an operation indicator light driving circuit 800 which is a dedicated driving circuit, and an input terminal T11 which is a dedicated input terminal.
Are provided in the integrated circuit IC1. As described above, since the conventional photoelectric switch requires a dedicated driving circuit for the operation indicator, it is necessary to secure an area of the integrated circuit chip for the circuit, which is equivalent to the chip area of the integrated circuit. There is a problem that it becomes an obstacle to downsizing, downsizing of the package of the integrated circuit, and downsizing of the photoelectric switch.

In order to make an integrated circuit multifunctional in order to make the integrated circuit versatile, it is necessary to increase the number of input / output terminals in accordance with the increase in functions. However, it is difficult to provide a large number of new terminals on an integrated circuit having a limited size, and in a conventional photoelectric switch that requires a dedicated input terminal for an operation indicator, a dedicated photoelectric switch for the operation indicator is used. There is a problem that the necessity of an input terminal is an obstacle to multifunction.

Further, in an integrated circuit, power consumption is limited in order to prevent malfunction and destruction of the circuit due to heat generation. In such limited power consumption, if power dedicated to driving the operation indicator is secured, power that can be consumed by other circuits in the integrated circuit is reduced accordingly. If the power that can be consumed by other circuits in the integrated circuit is reduced, it becomes difficult to secure noise immunity of other circuits, and additional functions such as a self-diagnosis function for abnormal operation of the photoelectric switch are provided. There is a problem that it is difficult to provide functions.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a photoelectric switch and a photoelectric switch capable of reducing the size of an integrated circuit for the photoelectric switch and the size of the photoelectric switch. It is to provide the integrated circuit. Another object of the present invention is to provide a photoelectric switch capable of realizing a multifunctional integrated circuit of a photoelectric switch and an integrated circuit thereof. Still another object of the present invention is to provide a photoelectric switch capable of making a circuit in an integrated circuit of the photoelectric switch less susceptible to noise and an integrated circuit thereof.

[0049]

According to the present invention, there is provided an output transistor of a first conductivity type or a second conductivity type, and a detection output is generated by operating the output transistor. And a first output terminal, a second output terminal, and an operation notifying unit.

The first output terminal is for outputting a potential to which an output transistor of the first conductivity type can be connected and which can operate the output transistor. The second output terminal is for outputting a potential to which an output transistor of the second conductivity type can be connected and which can operate the output transistor.
The operation notifying means is connected to the one of the first and second output terminals to which the output transistor is not connected, and that the photoelectric switch is operating based on the potential of the connected output terminal. It is for notifying.

As described above, when an output transistor of the first conductivity type is provided in the photoelectric switch, the output transistor is connected to the first output terminal. On the other hand, when the photoelectric switch is provided with an output transistor of the second conductivity type, the output transistor is connected to the second output terminal. That is, an output transistor of one of the first conductivity type and the second conductivity type is connected to an output terminal corresponding to the conductivity type. An operation notifying unit is connected to an output terminal of the first and second output terminals to which the output transistor is not connected, and the operation notifying unit is configured to detect the operation based on the potential of the connected output terminal. It notifies that the switch is operating.

Since the operation notifying means is connected to the vacant one of the first and second output terminals, it is not necessary to provide a dedicated drive circuit and terminal for the operation notifying means. Therefore, the size of the integrated circuit and the size of the photoelectric switch can be reduced. Furthermore, since it is not necessary to provide a dedicated drive circuit and a terminal for the operation notifying means, it is possible to increase power that can be used other than the operation of the operation notifying means, and to connect the operation notifying means. The number of terminals used to realize other functions can be increased by the reduced number of terminals. Furthermore, since the power that can be used for operations other than the operation of the operation notifying unit can be increased, the power that can be used for circuits other than the operation notifying unit in the photoelectric switch can be increased. Each circuit of the switch can be made less susceptible to noise, and power for making the photoelectric switch multifunctional can be secured. Further, since there is no need to provide a terminal dedicated to the operation notifying means, the terminal which is no longer required can be used for multifunction of the photoelectric switch.

According to a second aspect of the present invention, a potential is supplied to an output transistor of the first conductivity type or the second conductivity type to generate a detection output by the operation of the output transistor, and the detection operation is performed. An integrated circuit for a photoelectric switch capable of supplying a potential to an operation notifying unit for notifying that there is a power supply and executing the notification,
A first output terminal and a second output terminal are included.

The first output terminal is to be connected to an output transistor of the first conductivity type or an operation notifying means, and to output a potential at which the output transistor or the operation notifying means can be operated. . The second output terminal is for outputting a potential to which the output transistor or the operation notifying means of the second conductivity type can be connected and which can operate the connected output transistor or the operation notifying means. .

When an output transistor of the first conductivity type is used, the output transistor is connected to the first output terminal. In this case, since the output transistor is not connected to the second output terminal, the operation output means is connected to the second output terminal. On the other hand, when an output transistor of the second conductivity type is used, the output transistor is connected to the second output terminal corresponding to the conductivity type. In that case, since the output transistor is not connected to the first output terminal, the operation output means is connected to the first output terminal.

As described above, in the integrated circuit for the photoelectric switch, since the operation notifying means can be connected to the output terminal for connecting the output transistor, the integrated circuit is provided with a drive circuit and a terminal dedicated to the operation notifying means. Eliminates the need. Therefore, the size of the integrated circuit and the size of the photoelectric switch can be reduced accordingly. Further, when it is not necessary to provide a drive circuit dedicated to the operation notifying means, power available to circuits other than the operation notifying means in the integrated circuit can be increased. As the power that can be used in the integrated circuit increases, each circuit in the integrated circuit can be made less susceptible to noise, and the power can be used for multi-functionality. it can. Further, when a terminal dedicated to the operation notifying means becomes unnecessary, the terminal can be used for realizing other functions, so that the photoelectric switch can be multi-functional.

[0057]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First Embodiment FIG. 1 is a circuit diagram showing a configuration of a photoelectric switch according to a first embodiment. The photoelectric switch shown in FIG. 1 is different from the photoelectric switch shown in FIG. 10 in the following points. The operation indicator 92 is connected to the power terminal T1 and the output terminal T for PNP.
3 are connected. Further, there is no input terminal dedicated to connection of the operation indicator.

As described above, in the photoelectric switch of FIG. 1, the operation indicator lamp 92 is connected to the output terminal T3 for the output transistor on which the output transistor 61 is not provided. There is no need to provide a dedicated terminal on the integrated circuit IC.

Next, a detailed configuration of the photoelectric switch of FIG. 1 will be described. FIG. 2 is a block diagram showing a detailed configuration of the photoelectric switch of FIG. The photoelectric switch shown in FIG. 2 differs from the photoelectric switch shown in FIG. 11 in the following points.

The operation indicator lamp 92 is not connected to the signal processing circuit 8, and the power supply terminal T1 and the PNP output terminal T
3 are connected. The operation indicator lamp 92 has an anode connected to the power supply terminal T1 and a cathode connected to the output terminal T3. Therefore, the operation indicator 92
Receives a power supply voltage from the external power supply circuit 52.

The integrated circuit IC is not provided with a terminal dedicated to the operation indicator lamp 92 as described above. Therefore,
The signal processing circuit 8 corresponding to the above-described signal processing circuit 8a does not include a drive circuit dedicated to the operation indicator lamp 92 as shown in FIG. Further, a light receiving circuit 80 is provided in the integrated circuit IC. In addition, an input terminal, an output terminal, and a coupling capacitor related to the light receiving circuit as shown in FIG. 12 are not provided. The light receiving circuit 80 includes a photodiode (FDi) 81 and an I / V
A conversion amplifier circuit 82 is included. Further, the configuration of the output circuit 31 is different from that shown in FIG. The details will be described later.

Next, the output processing circuit 3 will be described in detail. FIG. 3 is a circuit diagram showing a configuration of the output processing circuit 3. Referring to FIG. 3, output processing circuit 3 shown in FIG. 3 is different from that shown in FIG. 13 in the following point. A short-circuit current flows from the load L to the output transistor connected to the output terminal T3 or the output terminal T4.
When the signal is detected by the NP-side detection circuit 321 or the NPN-side detection circuit 322, a circuit that supplies an H-level signal to the output prohibition circuit 33 in response to the detection is provided by the AND circuit 3.
23. The AND circuit 323 receives the output signal of the PNP detection circuit 321 at one input terminal, and receives the output signal of the NPN detection circuit 3W2 at the other input terminal. The output terminal of the AND circuit 323 is connected to the output inhibit circuit 3
3 is connected.

Next, the operation of the photoelectric switch according to the first embodiment will be described focusing on the operation of the portion shown in FIG. FIG. 4 is a timing chart showing the operation timing of the photoelectric switch according to the first embodiment. FIG. 4 shows an operation example when a short-circuit current flows through the output transistor 61.

Specifically, FIG. 4 shows the output potential E of the AND circuit 323, the output potential bP of the PNP side detection circuit 321 and
The output potential bN of the NPN side detection circuit 322, the output terminal T3
And the potential a of the output terminal T4.

Referring to FIG. 4, when an object is detected by the photoelectric switch and signal S1 output from signal processing circuit 8 attains H level, transistors 311, 312, 31
3 are all turned on, the potential b falls below the L-level threshold voltage V _P of the PNP-side detection circuit 32. In such a state, the current Ib flows through the operation indicator lamp 92 to turn on the operation indicator lamp 92, and the output potential bP
Rises to the H level.

Further, in that state, the potential a rises and the output transistor 61 is turned on.
In this case, if the short-circuit current Ia does not flow from the load L to the output transistor 61, in that state, the output potential E
Is at the L level, and the output prohibition circuit 33 does not prohibit the supply of the signal S1. However, as shown in FIG.
Is equal to or higher than the threshold voltage V _N of the NPN side detection circuit 322, the NPN side detection circuit 322 detects that a short-circuit current has flown, and the output potential bN becomes H level. In this case, the output potential E becomes H level, and the output prohibition circuit 33 prohibits the supply of the signal S1.

When the supply of the signal S1 is prohibited, the transistors 311 312 and 313 are all turned off. In response, the output transistor 61 is turned off and the operation indicator 92 is turned off. It is turned off. Therefore, the short-circuit detection circuit 32
When the side detection circuit 321 and the NPN side detection circuit 322 both detect a short-circuit current, it is determined that a short-circuit current from the load L has been detected.

Next, an example of a photoelectric switch when a PNP type output transistor 64 is connected to the integrated circuit IC will be described. FIG. 5 is a circuit diagram showing a configuration of a main part of a photoelectric switch using a PNP type output transistor. This figure 5
2 shows a portion of the photoelectric switch corresponding to the portion shown in FIG.

The photoelectric switch of FIG. 5 differs from that of FIG. 3 in the following point. Output terminal T24 and ground node GN
The load L is connected to the load D. A power terminal T1,
Between the output terminal T24, a resistance element 65 and an output transistor 64 are connected in series. The output transistor 64 has a base connected to the output terminal T3, an emitter connected to one end of the resistance element 65, and a collector connected to the output terminal T24. The operation indicator lamp 92 is connected between the output terminal T4 and the power terminal T2 in such a manner that the anode is connected to the output terminal T4 and the cathode is connected to the power terminal T2.

That is, contrary to the case shown in FIG.
The output transistor 64 is connected to the output terminal for PNP, and the operation indicator 92 is connected to the output terminal T4 for NPN.
Is connected. When a PNP-type output transistor is used, the connection mode is as shown in FIG. Next, the operation of the photoelectric switch shown in FIG. 5 will be described. In the following description, as in the case of FIG. 3, the operation of the photoelectric switch will be described focusing on the operation of the portion shown in FIG.

FIG. 6 is a timing chart showing the operation timing of the photoelectric switch when a PNP type output transistor is used. FIG. 6 shows an operation example when the short-circuit current Ib flows through the output transistor 64. Specifically, FIG. 6 shows, as in the case of FIG.
Output potential E of AND circuit 323, NPN side detection circuit 32
2, an output potential bN of the PNP-side detection circuit 321, an output potential bP of the output terminal T3, and a potential a of the output terminal T4.

Referring to FIG. 6, when an object is detected by the photoelectric switch and signal S1 output from signal processing circuit 8 attains an H level, transistors 311, 312 and 313 are turned on, and potential a is increased. It rises to or more H-level threshold voltage V _N. In such a state, the current Ib flows through the operation indicator lamp 92 to turn on the operation indicator lamp, and the potential bN rises to the H level.

Further, in that state, the output terminal T
The potential b of the third transistor 3 decreases, and the output transistor 64 is turned on. In this case, if no short-circuit current flows from the load L to the output transistor 64, the PNP side detection circuit 3
21 does not detect the short-circuit current, and the output potential bP is at the L level. In this state, the output potential E is at the L level, and the output inhibition circuit 33 does not inhibit the supply of the signal S1.
However, as shown in FIG. 6, when the potential b is equal to or lower than the threshold voltage V _P of the PNP-side detection circuit 321, PNP side detection circuit 321 detects the short-circuit current, the output potential of the PNP-side detection circuit 322 bP Becomes H level. In this case, the output potential E becomes H level, and the output prohibition circuit 33 prohibits the supply of the signal S1.

When the supply of the signal S1 is prohibited, the transistors 311 and 312 and 313 are all turned off. In response, the output transistor 64 is turned off and the operation indicator 92 is turned off. It is turned off. Therefore, the short-circuit detection circuit 32
When both the side detection circuit 321 and the NPN side detection circuit 322 detect a short-circuit current, it is determined that a short-circuit current has been detected.

In the photoelectric switch according to the first embodiment which can use the NPN output transistor 61 or the PNP output transistor 64 described above, the PNP output terminal T3 and the NPN output terminal T4 Of these, the operation indicator lamp 92 is connected to the output terminal on which the output transistor is not provided, and the operation indicator lamp 92 is operated according to the potential of the output terminal.

The short-circuit detection circuit 32 is connected to the power supply terminal T
1 and the output terminal T3, a short-circuit current is detected by the PNP-side detection circuit 321 and NPN is detected based on a voltage between the power supply terminal T2 and the output terminal T4.
When the short-circuit current is detected by the side detection circuit 322,
A signal indicating that a short-circuit current has flowed to the output transistor is output.

Therefore, even if the operation indicator lamp 92 is connected to the output terminal to which the output transistor is not connected,
The operation indicator 92 does not hinder the detection of the short-circuit current. For this reason, the operation indicator lamp 92 can be connected to one of the output terminals T3 and T4 for PNP and NPN without interrupting the function of the conventional photoelectric switch.

Further, since the operation indicator lamp 92 is connected to one of the output terminals T3 and T4,
It is not necessary to provide a terminal dedicated to the operation indicator light 92 in the integrated circuit IC, and it is not necessary to provide a drive circuit dedicated to the operation indicator light 92 in the integrated circuit IC. For this reason,
The chip of the integrated circuit IC can be made smaller than before, and accordingly, the size of the package containing the integrated circuit IC and the size of the entire photoelectric switch can be reduced.

Further, since the operation indicator lamp 92 is driven based on the power for driving the output transistor, it is not necessary to secure the power dedicated to drive the operation indicator lamp 92 in the integrated circuit IC. For this reason, the electric power conventionally used exclusively for driving the operation indicator lamp 92 can be supplied to other circuits in the integrated circuit IC. As a result, a large amount of current can flow through a circuit that is easily affected by noise, such as the photodiode 81, so that such a circuit that is easily affected by noise can be made less susceptible to noise. Furthermore, the operation indicator lamp 9
The power used as the dedicated power can be used to increase the function of the integrated circuit IC.
Multifunctionalization of C can be realized.

Further, an operation indicator 9 is provided between the output terminal provided with the output transistor and the output transistor.
It is conceivable to eliminate the dedicated terminal and the driving circuit for the operation indicator light as in the first embodiment by connecting the power supply 2. In such a case, however, the variation of the forward voltage of the operation indicator light is large. As a result, the variation in the voltage of the output terminal to which the operation indicator lamp is connected increases, and a malfunction may occur in the operation of detecting the short-circuit current by the short-circuit detection circuit 32. On the other hand, according to the first embodiment, the operation indicator lamp 92 is connected to the output terminal to which the output transistor is not connected, and the operation indicator lamp 92 is always turned on when a detection signal is output. With this configuration, even when the forward voltage of the operation indicator lamp 92 varies, the detection operation of the short-circuit detection circuit 32 is not adversely affected.

Further, in the conventional photoelectric switch shown in FIG. 13, similarly to the first embodiment, it is conceivable to connect the operation indicator lamp 92 to the output terminal of the output transistor to which the output transistor is not connected. However, this method has the following disadvantages. That is, in the integrated circuit IC1 shown in FIG.
Are the PNP side detection circuit 321 and the NPN side detection circuit 3
When one of the detection circuits 22 detects a short-circuit current, the operation indicator lamp 92 is connected to the output terminal to which the output transistor is not connected in order to judge that the short-circuit current has flowed to the output transistor. Then, the short-circuit current is always detected.

On the other hand, in the photoelectric switch according to the first embodiment, the short-circuit detection circuit 32 is
When both the NPN detection circuit 21 and the NPN-side detection circuit 322 detect the short-circuit current, it is determined that the short-circuit current has flowed through the output transistor. Therefore, even if the operation indicator lamp 92 is connected to the output terminal on which the output transistor is not provided, the short-circuit detection circuit 32 detects that the short-circuit current always flows, as in the conventional case. Not something. Thus, in the photoelectric switch according to the first embodiment, sufficient measures are taken to connect the operation indicator lamp 92 to the output terminal to which the output transistor is not connected.

In this embodiment, the operation indicator lamp 92 is provided as a notification means for notifying that the photoelectric switch is operating. However, the present invention is not limited to this.
Instead of or in addition to the operation indicator lamp 92, an integrated circuit IC
May be attached to the output terminal to which the output transistor is not connected.

Hereinafter, modified examples of the output processing circuit 30 shown in FIGS. 3 and 5 will be described as second to fourth embodiments.

Second Embodiment In the second embodiment, when a short-circuit current is detected,
An example in which control for turning off the output transistor for a predetermined period will be described. FIG. 7 is a circuit diagram illustrating a configuration of a main part of the photoelectric switch according to the second embodiment. FIG. 7 shows a modification of the output processing circuit 30 shown in FIGS.

Referring to FIG. 7, output processing circuit 20 is formed in the integrated circuit of the photoelectric switch, and
1, a short circuit detection circuit 22 and an output prohibition circuit 23 are included. The output circuit 21 includes PNP-type transistors 21a to 21a.
21c, includes NPN-type transistors 21d to 21j, and resistance elements 21k and 21m to 21p. The short-circuit detection circuit 22 includes a PNP-side detection circuit 221, an NPN-side detection circuit 222, and a NOR circuit 223. The PNP-side detection circuit 221 includes a PNP-type transistor 221a,
NPN transistor 221b, capacitor 221
c, and resistance elements 221d to 221g. NP
The N-side detection circuit 222 includes an NPN-type transistor 222
a, the capacitor 222b, and the resistance element 222c,
222d. The output inhibition circuit 23 includes flip-flops 23a to 23c, an 8-bit counter 23d, and AND circuits 23e to 23g.

In the output circuit 21, when a signal responsive to the H-level signal S1 is supplied to the base of the transistor 21j via the output inhibition circuit 23, the transistor 21j is turned on. When the transistor 21j is turned on, the potential of the base of the transistor 21d is increased, the transistor 21d is turned on, and in response, the transistors 21e and 21f are also turned on.

In the output circuit 21, the transistor 21
a, 21b, 21g to 21i and resistance elements 21k to 2
1n constitutes a constant current source for supplying a constant current into the output circuit 21. A constant current is supplied from the constant current source to the transistors 21d and 21e.

As described above, the transistors 21d and 21d
When e and 21f are turned on, the potential of the output terminal T3 decreases and the potential of the output terminal T4 increases.
Accordingly, when an output transistor is connected to the output terminal T3 or T4, the output transistor is turned on. On the other hand, when an operation indicator is connected to the output terminal T3 or T4, , Its operation indicator lights up.

The short detection circuit 22 operates as follows. When the potential of the output terminal T3 decreases, the PNP side detection circuit 221 responds to the decrease in the potential of the output terminal T3.
221a voltage-divided by transistors 221e and 221e
Of the base of the transistor falls. When the potential of the base becomes equal to or lower than a predetermined threshold, transistor 221a is turned on, and current flows through resistance elements 221f and 221g.

When a current flows through the resistance elements 221f and 221g, the potential at the base of the transistor 221b increases due to the voltage division by the resistance elements, and the transistor 221b is turned on. When the transistor 221b is turned on, the charge stored in the capacitor 221c decreases, and the potential of one input terminal of the NOR circuit 223 goes to L level.

The NPN side detection circuit 222 has an output terminal T4
When the potential of the transistor 222a rises above a predetermined threshold value, the transistor 222a is turned on. When the transistor 222a is turned on, the capacitor 2
The charge stored in the NOR circuit 22b decreases, and the NOR circuit 22b
The potential of the other input terminal of No. 3 becomes L level.

As described above, when the levels of the two input terminals of the NOR circuit 223 both become L level, the level of the output terminal of the NOR circuit 223 becomes H level. In response, the output of flip-flop 23a goes high, and in response, the output of flip-flop 23b goes high. As a result, the potential levels of all the input terminals of the AND circuit 23e become H level,
The potential of the output terminal of the D circuit 23e becomes H level. Thereby, the clear input terminal CL of the 8-bit counter 23d
The potential of each of R and the set input terminal S of the flip-flop 23c becomes H level.

Thus, the 8-bit counter 23d starts counting, and the signal S2 output from the inverted output terminal bar Q of the flip-flop 23c goes low. When the signal S2 is at the L level, the output of the AND circuit 23g does not go to the H level even if the signal S1 goes to the H level. In this way, output of a signal responsive to the signal S1 is prohibited.

In the 8-bit counter 23d, when 8 bits are counted in synchronization with the clock signal CLK,
All the output signals of the eight output terminals become H level.
In such a state, the potential of the output terminal of the AND circuit 23f becomes H level, the level of the reset input terminal R of the flip-flop 23c receiving the H level potential becomes H level, and the flip-flop 23c is reset. , The signal S2 output from the inverting output terminal Q of the flip-flop 23c goes high. This allows
The output of the AND circuit 23g becomes H in accordance with the level of the signal S1.
It becomes a state where it can be at the level, and the inhibition state of the signal responsive to the signal S1 is released.

As described above, in the photoelectric switch according to the second embodiment, the detection output of the photoelectric switch is provided for a predetermined period after the short-circuit current is detected by the short-circuit detection circuit 22 because the 8-bit counter 23d functions as a timer. It is forbidden.

Third Embodiment Next, a third embodiment will be described. In the third embodiment, an example of a photoelectric switch in which an output transistor is kept stopped when a short-circuit current is detected will be described.

FIG. 8 is a circuit diagram showing a configuration of a main part of a photoelectric switch according to the third embodiment. In FIG. 8, the same parts as those in FIG. 7 are denoted by the same reference numerals, and overlapping description will not be repeated. Note that the output circuit 21, the PNP side detection circuit 221 and the NPN side detection circuit 222 are the same as those in FIG. 7, and therefore, reference numerals of elements such as transistors and resistance elements are omitted in the drawings.

The photoelectric switch of FIG. 8 differs from that of FIG. 7 in the following point. The short circuit detection circuit 22a includes a NOR circuit 224 having one output terminal. The output prohibition circuit 230 includes an OR circuit 230a in addition to the AND circuit 23g.
And a flip-flop 230b.

Next, the operation of the photoelectric switch of FIG. 8 will be described. PNP side detection circuit 221 and NPN side detection circuit 2
22, when the short-circuit current is detected and the level of the output signal of the NOR circuit 224 becomes H level, the OR circuit 230
The output signal of “a” becomes H level. When the flip-flop 230b takes in the H-level signal in synchronization with the clock signal CLK, the level of the signal S2 output from the inverted output terminal Q of the flip-flop 230b becomes L-level.

In response, AND circuit 23g stops outputting a signal corresponding to signal S1, and the operation of the output transistor is stopped. Such a state is maintained by continuously outputting an H-level signal from the output terminal Q of the flip-flop 230b to one input terminal of the OR circuit 230a.

Fourth Embodiment Next, a fourth embodiment will be described. In the fourth embodiment, an example of a photoelectric switch in which an output transistor is stopped only when a short-circuit current is detected will be described. FIG.
It is a circuit diagram showing the composition of the important section of the photoelectric switch by a 4th embodiment. In FIG. 9, the same parts as those in FIG. 8 are denoted by the same reference numerals, and the description thereof will not be repeated.

The photoelectric switch of FIG. 9 differs from that of FIG. 8 in that the short-circuit detection circuit 231 includes an inverter 231a in addition to the AND circuit 23g.

Next, the operation of the photoelectric switch shown in FIG. 9 will be described. PNP side detection circuit 221 and NPN side detection circuit 2
When a short-circuit current is detected in both the circuits 22 and the level of the output signal of the NOR circuit 224 becomes H level, the level of the signal is inverted by the inverter 231a and supplied to the input terminal of the AND circuit 23g as the signal S2. In response, AND circuit 23g stops outputting a signal corresponding to signal S1, and the operation of the output transistor is stopped. Such a state ends when the short circuit current is no longer detected by the short circuit detection circuit 22a.

As shown in the second embodiment, the output prohibition circuit may prohibit output for a predetermined period after a short-circuit current is detected. Further, as shown in the third embodiment, the output prohibition circuit may continue to prohibit the output after the short-circuit current is detected. Also, as shown in the fourth embodiment,
The output prohibition circuit may prohibit the output only when the short-circuit current is detected.

The short-circuit detection circuit is a circuit which outputs a signal of a different level from that of the other circuit when both the PNP-side detection circuit and the NPN-side detection circuit detect a short-circuit current. Either of the circuits may be employed.

[0108]

[Specific example of means for solving the problem]

[1] An output transistor (output transistor 61) of the first conductivity type (NPN type) can be connected to the output terminal T4 shown in FIG. 3 and the like, and the potential at which the output transistor can be operated is set to a potential. A first output terminal for outputting is configured. An output transistor (output transistor 64) of the second conductivity type (PNP type) can be connected to the output terminal T3 shown in FIG. 3 and the like, and the output transistor T3 outputs a potential at which the output transistor can be operated. Of the second output terminal. The operation indicator lamp 92 shown in FIG. 3 or the like is connected to the output terminal of the first and second output terminals to which the output transistor is not connected, and based on the potential of the connected output terminal, Operation notification means for notifying that the photoelectric switch is operating is configured.

[2] The integrated circuit IC shown in FIG. 3 or the like supplies a potential to an output transistor of the first conductivity type (NPN type) or the second conductivity type (PNP type) to supply the potential to the output transistor. An integrated photoelectric switch capable of generating a detection output by an operation and supplying a potential to an operation notifying means (operation indicator lamp 92) for notifying that a detection operation is being performed and executing the notification. The circuit is configured. The output transistor T4 of the first conductivity type or the operation notifying means (operation indicator light 92) can be connected to the output terminal T4 shown in FIG. 3 and the like, and the connected output transistor or the operation notifying means is connected. A first output terminal for outputting a potential capable of operating the device. An output transistor (output transistor 64) of the second conductivity type or an operation notifying means (operation indicator light 92) can be connected to the output terminal T3 shown in FIG. 3 and the like, and the connected output transistor or the operation notifying means is connected. A second output terminal for outputting a potential at which the device can operate.

[3] The operation notifying means may be notifying means using light from a light emitting diode or the like, or may be notifying means using sound from a speaker or the like.

[4] Other Specific Examples of the Present Invention Other specific examples of the present invention will be listed below.

(1) A photoelectric transistor having an output transistor of the first conductivity type (NPN type) or the second conductivity type (PNP type) and capable of generating a detection output by operating the output transistor. A switch,
An output transistor (output transistor 61) of the first conductivity type is connectable, and a first output terminal (output terminal T4) for outputting a potential capable of operating the output transistor; And a second output terminal (output terminal T3) for outputting a potential at which an output transistor (output transistor 64) of the second conductivity type can be connected and which can operate the output transistor.
And the effect that the photoelectric switch is operated based on the potential of the connected output terminal, which is connected to the output terminal of the first and second output terminals to which the output transistor is not connected. And an operation notifying means (operation indicator lamp 92) for notifying that the potential of the first output terminal becomes a predetermined first potential (V _N ) and the second output terminal The potential is a predetermined second potential (V
_P ), a photoelectric switch including abnormality determination means (short-circuit detection circuit 32) for determining that an abnormal detection output state has occurred.

In this way, when the potential of the first output terminal becomes abnormal and the potential of the second output terminal becomes abnormal, it can be determined that an abnormal detection output has occurred. Therefore, even if the operation notifying unit is connected to one of the first and second output terminals, the operation of the operation notifying unit does not adversely affect the operation of the abnormality determining unit.

(2) A potential is supplied to an output transistor of the first conductivity type (NPN type) or the second conductivity type (PNP type) to generate a detection output by the operation of the output transistor, and the detection operation is performed. A photoelectric switch integrated circuit (IC) capable of supplying an electric potential to an operation notifying means (operation indicator light 92) for notifying that the operation is being performed, and executing the notification; A conductive type output transistor (output transistor 61) or the operation notifying means (operation indicator lamp 92) can be connected to output a potential at which the connected output transistor or the operation notifying means can be operated. And an output transistor of the second conductivity type (output transistor 64) or the operation notifying means (operation indicator lamp 92). A second output terminal (output terminal T3) for outputting a potential that is connectable and capable of operating the connected output transistor or the operation notification means, and a potential of the first output terminal. When the potential of the second output terminal becomes the predetermined first potential (V _N ) and the potential of the second output terminal becomes the predetermined second potential (V _P ), an abnormal detection output state occurs. An integrated circuit for a photoelectric switch, including an abnormality determining means (short-circuit detection circuit 32) for determining occurrence of the occurrence.

In this way, it is determined that an abnormal detection output has occurred when the potential of the first output terminal becomes an abnormal potential and the potential of the second output terminal becomes an abnormal potential. Since it is possible, even if the operation notifying means is connected to one of the first and second output terminals, the operation of the operation notifying means does not adversely affect the operation of the abnormality determining means.

[0116]

According to the first aspect of the present invention, the operation notifying means is connected to the one of the first and second output terminals to which the output transistor is not connected, so that the operation notifying means is provided. Since there is no need to provide a dedicated terminal and a drive circuit, the size of the integrated circuit for the photoelectric switch and the size of the photoelectric switch can be reduced. Further, since a terminal and a drive circuit dedicated to the operation notifying means are not required, the terminal which has become unnecessary and power for driving the drive circuit can be used for multifunction of the integrated circuit of the photoelectric switch. Thus, the integrated circuit of the photoelectric switch can be made multifunctional. Further, by supplying such power to a circuit susceptible to noise in the photoelectric switch, such a circuit susceptible to noise can be made less susceptible to noise.

According to the second aspect of the present invention, it is possible to connect an output transistor of the first conductivity type or an operation notifying means to the first output terminal, and to connect the second output terminal to the second output terminal. Since it is possible to connect a conductive type output transistor or operation notifying means, it is possible to connect the operation notifying means to the output terminal to which the output transistor is not connected. Therefore, since it is not necessary to provide a terminal and a drive circuit dedicated to the operation notifying means in the integrated circuit, the size of the integrated circuit for the photoelectric switch and the size of the photoelectric switch can be reduced. Further, since a terminal and a driving circuit dedicated to the operation notifying means are unnecessary, the terminal and the power for driving the driving circuit and the integrated circuit of the photoelectric switch which have become unnecessary can be used for multifunctionalization of the photoelectric switch. The multifunction of the integrated circuit of the switch can be achieved. Further, by supplying such power to circuits susceptible to noise in the integrated circuit, circuits in the integrated circuit of the photoelectric switch can be made less susceptible to noise.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a photoelectric switch according to a first embodiment.

FIG. 2 is a block diagram illustrating a detailed configuration of the photoelectric switch of FIG. 1;

FIG. 3 is a circuit diagram illustrating a configuration of an output processing circuit according to the first embodiment.

FIG. 4 is a timing chart showing operation timing of a photoelectric switch when an NPN output transistor is used.

FIG. 5 is a circuit diagram showing a configuration of a main part of a photoelectric switch when a PNP type output transistor is used.

FIG. 6 is a timing chart showing operation timing of a photoelectric switch when a PNP output transistor is used.

FIG. 7 is a circuit diagram showing a configuration of a main part of a photoelectric switch according to a second embodiment.

FIG. 8 is a circuit diagram illustrating a configuration of a main part of a photoelectric switch according to a third embodiment.

FIG. 9 is a circuit diagram showing a configuration of a main part of a photoelectric switch according to a fourth embodiment.

FIG. 10 is a circuit diagram showing a configuration of a conventional photoelectric switch.

FIG. 11 is a block diagram showing a detailed configuration of a conventional photoelectric switch.

FIG. 12 is a circuit diagram showing a detailed configuration of an operation indicator driving circuit.

FIG. 13 is a circuit diagram showing a configuration of a conventional output processing circuit of a photoelectric switch.

[Explanation of symbols]

 T3, T4 Output terminal 61, 64 Output transistor 20, 3 Output processing circuit 21, 31 Output circuit 22, 22a, 32 Short circuit detection circuit 23, 33, 230, 231 Output inhibition circuit IC integrated circuit

Claims (2)

[Claims] 1. A photoelectric switch having an output transistor of a first conductivity type or a second conductivity type and capable of generating a detection output by operating the output transistor, An output transistor of a conductivity type is connectable, a first output terminal for outputting a potential capable of operating the output transistor, and an output transistor of the second conductivity type is connectable, A second output terminal for outputting a potential capable of operating the output transistor, and a second output terminal connected to the output terminal of the first and second output terminals to which the output transistor is not connected, An operation notifying unit for notifying that the photoelectric switch is operating based on the potential of the connected output terminal. 2. A method for supplying a potential to an output transistor of a first conductivity type or a second conductivity type to generate a detection output by an operation of the output transistor and to notify that a detection operation is being performed. A photoelectric switch integrated circuit capable of supplying a potential to the operation notifying means and causing the operation notifying means to execute the notification, wherein the output transistor of the first conductivity type or the operation notifying means is connectable, and A first output terminal for outputting a potential capable of operating the transistor or the operation notifying unit, and the second conductive type output transistor or the operation notifying unit can be connected to the first output terminal; A photoelectric switch, comprising: an output transistor or a second output terminal for outputting a potential capable of operating the operation notifying means. Integrated circuit.