JPH05102823A - Photoelectric switch - Google Patents

Abstract

PURPOSE:To allow a floodlight device to make light receiving detection display and stable input light display while keeping two signal lines between the floodlight device and a main body section. CONSTITUTION:A main body section 1 and a floodlight device 2 are interconnected by signal lines 4, 5. The floodlight device 2 consists of a floodlighting LED 8, a light receiving detection display LED 9, a resistor 10, a stable input light display LED 11 and a transistor(TR) 12. The main body section 1 consists of a signal generating circuit 13 outputting a floodlight signal, a light receiving signal processing circuit 36 outputting a light receiving detection signal and a stable incoming light detection signal and a display drive circuit 38 or the like. When a light receiving detection signal is given to the flood light device 2 via the signal lines 4, 5, the light receiving detection display LED 9 is lighted and when a stable incident light detection signal is given to the device 2, the light receiving detection display LED 9 and the stable input light display LED 11 are both lighted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric switch having a main body, a light receiver and a light projector, at least the light emitter being connected to the main body by two signal lines.

[0002]

2. Description of the Related Art As a structure of a photoelectric switch, there is one in which a light transmitter and a light receiver are separated from a main body portion in which an amplifier, a signal processing circuit and the like are arranged. In such a configuration, the projector or the light receiver is connected to the main body by a signal line, and signals are transmitted and received to and from the main body via the signal line. Therefore, since the projector and the light receiver can be miniaturized, restrictions on the installation place are lessened, and there is an advantage that the range of use is wide and it is easy to use.

However, in the case where the main body is separately provided in this way, since the light reception detection is also displayed on the main body, the light receiving state is checked every time when the projector and the light receiver are installed. Since it had to be done in the place, there was a problem that the installation work was troublesome and took time.

In order to solve such a problem, for example, it is considered to provide a light receiving detection display unit in the light projector. In that case, a signal line for giving a signal for light receiving detection display from the main body to the light projector. Will increase,
There has been a problem that wiring man-hours increase and erroneous wiring and reliability decrease easily.

Therefore, conventionally, for example, the following has been considered. That is, the two signal lines between the projector and the main body are left as they are, and the light emitting diode for display is connected to the projector side in parallel with the projector element in reverse polarity, and the main body emits the signal via the signal line. The light emitting pulse is applied to the optical element to turn on the light intermittently, and at the non-output timing of the light emitting pulse, the display element is turned on by giving a pulse-shaped display signal having a polarity opposite to that of the light emitting pulse from the main body through the signal line. It was made to let.

As a result, even if the projector is provided separately from the main body, it is possible to cause the projector to perform light reception detection display without increasing the number of signal lines, and the above-mentioned problems can be solved.

[0007]

However, in recent years,
In addition to the received light detection display, some photoelectric switches have a stable light input display function for displaying that the level of the light reception signal exceeds the stable light input level set to a value higher than the detection level. It is becoming mainstream. If such two types of display functions are to be realized with the conventional structure as described above, the number of signal lines must be increased, which increases wiring man-hours and causes incorrect wiring and reliability. There is a problem that causes a decrease.

The present invention has been made in view of the above circumstances. An object of the present invention is to keep the number of signal lines as two even if at least the projector is provided separately from the main body, and to use two types on the projector side. It is to provide a photoelectric switch capable of displaying.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a photoelectric switch having a main body, a light receiver, and a light emitter, and at least the light emitter is connected to the main body by two signal lines. A signal generating circuit provided in the main body for outputting a pulsed light projection signal; and a first pulsed display provided in the main body with a polarity opposite to that of the light projection signal at a non-output timing of the light projection signal. A signal and a display drive circuit for selectively outputting a second pulsed display signal having a peak value higher than that of the display signal; and energization lighting by the light projecting signal provided to the light projector through the signal line. A light emitting element, and a first display element which is provided in the light projector and is energized and lit through a resistor in a state where the first or second pulsed display signal is applied through the signal line. Provided on the floodlight A transistor that conducts by the terminal voltage of the resistor when the second pulse-shaped display signal is applied to the first display element, and a second transistor that is provided in the projector and is energized and turned on when the transistor is in the conductive state. It is characterized in that it is provided with a display element.

[0010]

According to the photoelectric switch of the present invention, the light projecting element arranged in the light projector is energized and lit by the pulsed light projecting signal given from the main body through the signal line, and the pulsed light is sent to the light receiver side. To project. The light receiver receives the light from the light projector and transmits the light reception signal to the main body. The main body section outputs the light projecting signal to the light projecting apparatus and selectively outputs the first or second pulsed display signal at the non-output timing of the light projecting signal. In this case, since the first and second pulsed display signals have the opposite polarities to the light projecting signal, the light projecting element is not driven and turned on. And the first
When the pulsed display signal of 1 is given, the first display element is energized through the resistor, and thus is turned on. When the second pulse-shaped display signal is applied, the first display element is energized, and the peak value of the second pulse-shaped display signal is higher than that of the first pulse-shaped display signal. The voltage shared by the transistor becomes large, the transistor becomes conductive, and the second display element also becomes conductive, and the transistor is turned on. Thereby, for example, in addition to the display of the received light detection, two types of display functions such as the display of the stable light detection can be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 shows a block structure. The overall structure is composed of a main body 1, a light projector 2 and a light receiver 3. Among these, two signal lines are provided between the main body 1 and the light projector 2. 4 and 5 are connected, and two signal lines 6 and 7 are connected between the main body 1 and the light receiver 3.

FIG. 1 shows an electrical structure of a main part, which will be described below. First, in the projector 2, the anode of the LED 8 for projecting, which is a projecting element, is connected to the signal line 4, and the cathode is connected to the signal line 5. The anode of the light receiving display LED 9 as the first display element is connected to the signal line 5, and the cathode is connected to the signal line 4 via the resistor 10.

LED for stable light input, which is the second display element
The anode of 11 is connected to the signal line 5, and the cathode is np
The n-type transistor 12 is connected to the signal line 4 through the collector and the emitter. The base of the transistor 12 is connected to the cathode of the light receiving display LED 9.

Next, in the main body 1, the signal generating circuit 1
Reference numeral 3 denotes a pulsed light-emission signal having a predetermined period, and its output terminal is connected to the base of the npn-type transistor 15 via the emitter-collector of the pnp-type transistor 14. The base of the transistor 14 is a resistor 16
It is connected to the signal line 5 via and is grounded. The collector of the transistor 15 is connected to the DC power supply terminal 17, and the emitter is grounded via the resistor 18 and the emitter-collector of the pnp transistor 19. The base of the transistor 19 is connected to the output terminal of the signal generating circuit 13, and the emitter is connected to the signal line 4.

One terminal of the capacitor 20 for lighting the display element is connected to the emitter of the transistor 19, and the other terminal is connected to the DC power supply terminal 17 through the resistor 21 and the collector / emitter of the pnp transistor 22. There is. The other terminal of the capacitor 20 is connected between the collector and the emitter of the npn transistor 23 and the resistor 24.
It is grounded via the npn transistor 2
It is grounded between the collector-emitter 5 and the resistor 26. The base of the transistor 22 is connected to the DC power supply terminal 17 via the resistor 27 and the resistor 28
And npn-type transistor 29 is grounded between the collector and emitter.

The output terminal of the signal generating circuit 13 is also connected to the input terminal of the monostable multivibrator 30. This monostable multivibrator 30 outputs an "H" level signal for a fixed time when a pulse signal is applied to its input terminal, and its output terminal is an AND circuit 3
1 is connected to one input terminal. The other input terminal of the AND circuit 31 is connected to the output terminal of the signal generating circuit 13 via the inverter circuit 32. And
The output terminal of the AND circuit 31 is connected to one input terminal of the NOR circuit 33 and is also connected to one input terminal of the AND circuit 34. The other input terminal of the NOR circuit 33 is connected to the output terminal of the signal generation circuit 13,
The output terminal of the circuit 33 is connected to one input terminal of the AND circuit 35.

The other input terminal of each of the AND circuit 34 and the AND circuit 35 is connected to an output terminal a of a light receiving signal processing circuit 36 provided in the main body 1, and a light receiving detection signal is received from the light receiving signal processing circuit 36. To be given. The output terminal of the AND circuit 34 is connected to the base of the transistor 25 and is also connected to one input terminal of the AND circuit 37. The output terminal of the AND circuit 35 is connected to the base of the transistor 29. AND circuit 3
The other input terminal of 7 is connected to the output terminal b of the received light signal processing circuit 36, and a stable light incident signal is given from the received light signal processing circuit 36. AND circuit 37
The output terminal of is connected to the base of the transistor 23.

In the main body 1 as described above, a portion excluding the signal generating circuit 13 and the light receiving signal processing circuit 36 is configured as a display driving circuit 38.

Next, the operation of this embodiment will be described with reference to FIG. The main body 1 gives a light projecting signal to the light projecting device 2 to perform (1) light projecting operation, and when light is detected by the light receiving device 3 by this light projecting, the light receiving signal at that time (2) detecting operation of the presence or absence of an object At the same time, the projector 2 is caused to display the light receiving state as to whether the light is being received in a stable state or in a non-stable state according to the level of the light receiving signal at that time. Hereinafter, these operations will be described in detail.

(1) Light Projecting Operation In the main body 1, the signal generating circuit 13 generates a pulsed light projecting signal having a predetermined cycle as shown in FIG. With this light emission signal, the transistor 14 is turned on, the transistor 15 is turned on, and the transistor 19 is turned off. As a result, a current flows from the DC power supply terminal 17 to the transistor 15, the resistor 18, the signal line 4, the light emitting LED 8 and the signal line 5, so that the light emitting LED 8
Lights up intermittently at the timing according to the light projection signal.

On the other hand, in the monostable multivibrator 30, each time the light projecting signal from the signal generating circuit 13 is applied, a signal of "H" level is output for a predetermined time as shown in FIG. 3 (e). It is input to the AND circuit 31.

(2) Detecting Operation Next, the light output from the LED 8 for light projection by the above-mentioned light projecting operation is received by the light receiver 3, and the signal line 6 from the light receiver 3 is received.
The received light signal is sent via 7 to the received light signal processing circuit 36 of the main body 1.
The detection operation in the case of being given to will be described. The following cases will be separately described depending on the presence or absence of an object that shields the optical axis and the light receiving level at that time.

(A) Light-shielded state When an object is present on the optical axis and no light is incident on the light receiver 3, there is no light reception signal from the light receiver 3 side. The circuit 36 is in a state in which neither the received light detection signal nor the stable incident light detection signal is output. Therefore, at this time, only the light projection signal appears between the signal lines 4 and 5 as shown in FIG.

(B) Unstable detection state Next, in the case where the light from the projector 2 is incident on the light receiver 3,
Although the level of the light reception signal of the light receiver 3 reaches the detection level, the operation in the state where the light reception level is not the stable light reception level, that is, the unstable detection state will be described.

That is, when the received light signal exceeds the detection level,
The received light signal processing circuit 36 of the main body 1 is connected to the first from the output terminal a.
The pulsed display signal of "H" level light reception detection signal (see FIG. 3C) is output. In this case, the light reception detection signal is output when the output signal of the monostable multivibrator 30 (see FIG. 3E) is inverted to the “L” level after the light projection signal is output. ..

When the received light detection signal is output, the output of the NOR circuit 33 becomes "H" level because the output of the monostable multivibrator 30 is at "L" level at that time. Output becomes "H" level (see FIG. 3 (g)). As a result, when the transistor 29 turns on, the transistor 22 also turns on. on the other hand,
Since the light emission signal of the signal generation circuit 13 is at the "L" level at this time, the transistor 19 is on.

Therefore, the capacitor 20 includes a DC power supply terminal 17, a transistor 22, a resistor 21, a capacitor 20,
A direct current flows through the energization path of the transistor 19 to start charging. Next, when the light emission signal becomes "H" level,
The output of the monostable multivibrator 30 also becomes "H" level, the output of the AND circuit 35 is inverted to "L" level, and the transistors 22 and 19 are turned off. As a result, the current of the capacitor 20 is cut off, so that the charging ends and the electric charge is accumulated between both terminals of the capacitor 20. The LED 8 for light emission is turned on while the light emission signal is at "H" level.

Then, when the light emission signal becomes "L" level, the output of the AND circuit 34 becomes "H" level while the output of the monostable multivibrator 30 is at "H" level, so that the transistor 25 is turned on. Turned on. This allows
The charge stored in the capacitor 20 flows through the transistor 25, the resistor 26, the signal line 5, the light receiving display LED 9, the resistor 10 and the signal line 4 through the energizing path, and the light receiving display LED 9 is turned on. At this time, since the resistance value of the resistor 26 is set so that the voltage drop by the resistor 10 does not turn on the transistor 12, the stable light-entering display LED 11 is not energized and is in the off state.

When the output of the monostable multivibrator 30 is inverted to the "L" level, the output of the AND circuit 34 also becomes the "L" level and the transistor 25 is turned off.
As a result, the light-receiving display LED 9 is cut off and turned off. Then, the capacitor 20 is charged again in the same manner as described above until the light emission signal is next inverted to the “H” level.

(C) Stable detection state Next, in the case of a stable detection state in which light is sufficiently incident on the photodetector 3 and the level of the received light signal exceeds the stable incident light level,
In addition to the light reception detection signal, the stable light reception detection signal (see FIG. 3D) at the “H” level which is the second pulsed display signal is output from the output terminal b of the light reception signal processing circuit 36. It should be noted that this stable incident light detection signal is also output when the output of the monostable multivibrator 30 is inverted to the "L" level in the same manner as the above-described received light detection signal.

Also in this case, the monostable multivibrator 3 is used.
When the output of 0 is inverted to "L" level, the capacitor 20 is charged in the same manner as described above. Then, after that, the light projecting signal becomes "H" level and the light projecting LED 8 is turned on.

Next, when the light projection signal is inverted to the "L" level, the light reception detection signal and the stable light reception detection signal are at the "H" level while the output of the monostable multivibrator 30 is at the "H" level. Therefore, the outputs of the AND circuits 34 and 37 are at the "H" level. As a result, the transistor 23 is turned on in addition to the transistor 25, so that the charge charged in the capacitor 20 also flows in the energization path via the transistor 23 and the resistor 24 in addition to the energization path described above. In other words, when the stable incident light detection signal is output substantially, the peak value becomes higher than when only the received light detection signal is output.

Therefore, the charge charged in the capacitor 20 flows through the energizing path in the state where the resistors 26 and 24 are connected in parallel, the voltage drop of the resistor 10 on the projector 2 side increases, and the transistor 12 is turned on. Like As a result, the light receiving display LED 9 and the stable light entering display LED
Both 11 will be energized and lit.

After that, if the stable light receiving state continues, the light receiving signal processing circuit 36 continues to output the light receiving detection signal and the stable light receiving detection signal, and the above-described operation is repeated. Further, when the stable light receiving state changes to the unstable light receiving state, the stable incident light detection signal is inverted to the “L” level and the operation in the unstable light receiving state is performed.

According to the present embodiment as described above, the light receiving detection display LED 9 is connected to the light projecting device 2 in antiparallel with the light projecting LED 8 through the resistor 10 in series, and is turned on at a predetermined terminal voltage by the resistor 10. Since the transistor 12 and the stable light-entering LED 11 connected in series to the transistor 12 are provided, the light-emitting LED 8 is energized and turned on by the light-emitting signal, and the light-reception detection signal and the stable light-incoming detection signal are detected in the opposite direction. The display and the stable light incident detection display can be performed. Therefore, only two signal lines 4 and 5 need be provided between the projector 2 and the main body 1, and the number of signal lines can be increased. It is possible to prevent erroneous wiring and decrease in reliability.

Further, according to the present embodiment, the reverse voltage applied to both terminals of the light emitting LED 8 when the light receiving detection display LED 9 and the stable light entering display LED 11 are operated can be made relatively small. Therefore, it is not necessary to separately provide a diode or the like for compensating the breakdown voltage. That is, the forward voltage of the LED 9 is about 2V, and the base-emitter voltage of the transistor 12 is about 0.7V.
It will take a maximum of 2.7V in the opposite direction,
Since the reverse breakdown voltage is about 3V, it can withstand it sufficiently.

FIG. 4 shows the second embodiment of the present invention.
The difference from the above embodiment is that a pnp transistor 39 is used in place of the npn transistor 12 of the projector 2. That is, the cathode of the LED 9 for light reception detection and display is connected to the signal line 4, and the anode is connected to the signal line 5 via the resistor 10. LED for stable light input
The cathode of 11 is connected to the signal line 4, and the anode is connected to the signal line 5 via the collector-emitter of the transistor 39.
It is connected to the.

With such a configuration, similarly to the first embodiment, the light emitting LED 8 is intermittently turned on by the light emitting signal from the signal generating circuit 13, and the light receiving detection display LED 9 is intermittently turned on by the light receiving detection signal. The LEDs 11 are turned on, and the stable incident light detection LED also causes the stable incident light display LED 11 to be turned on intermittently. Therefore, the same operation and effect as those of the first embodiment can be obtained by the second embodiment as well.

FIG. 5 shows the third embodiment of the present invention.
The difference from the embodiment is the connection relationship in the projector 2. That is, the light-emitting LED 8 is connected between both terminals of the resistor 10, and the stable light-entering display LED 11 is connected to the transistor 1
It is connected between the emitter of 2 and the signal line 4.

According to this structure, when the light projecting signal is given through the signal lines 4 and 5, the light projecting LED 8 is used.
And a current flows through the forward diode portion between the base and collector of the transistor 12 so that L
The ED 8 is energized and lit. Further, when a light reception detection signal is given, a current flows through the light reception detection display LED 9 and the resistor 10, so that the light reception detection display LED 9
Is turned on and a stable light detection signal is given, in addition to turning on the light reception detection LED 9, the transistor 12 is turned on by the terminal voltage of the resistor 10 and the stable light input LED 11 is also turned on. Become so. Therefore, according to the third embodiment, the same effect as that of the above-described embodiment can be obtained.

FIG. 6 shows a fourth embodiment of the present invention. The difference from the second embodiment in its construction is that the LED 8 for projecting light is connected between both terminals of the resistor 10 and stable light reception is achieved. The display LED 11 is just connected between the emitter of the transistor 39 and the signal line 5.

According to the present embodiment as described above, the same operation as that of the third embodiment can be obtained, and the same effect as that of the first embodiment can be obtained.

[0044]

As described above, according to the photoelectric switch of the present invention, the first and second pulse-shaped display signals are applied to the projector via the signal line at the non-output timing of the projector signal. Is a first and second display element connected in reverse polarity to the light projecting element, a resistor and a transistor,
Since the first display element is turned on by the first pulsed light projecting signal and the first and second display elements are turned on by the second pulsed display signal, miswiring of signal lines and reliability This has an excellent effect that two display functions can be performed with two signal lines as it is without causing a decrease.

[Brief description of drawings]

FIG. 1 is an electrical configuration diagram of essential parts showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram of the overall configuration.

FIG. 3 is a time chart showing a signal output state of each part.

FIG. 4 is an electrical configuration diagram of a floodlight portion showing a second embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 4, showing a third embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 4 showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 is a main body, 2 is a light emitter, 3 is a light receiver, 4 to 7 are signal lines, 8 is a light emitting LED (light emitting element), and 9 is a light receiving display L.
ED (first display element), 10 is a resistor, 11 is a stable light-entering display LED (second display element), 12 is an npn-type transistor, 13 is a signal generating circuit, 17 is a DC power supply, 20
Is a condenser, 30 is a monostable multivibrator, 3
1, 34, 35 and 37 are AND circuits, 33 is a NOR circuit, 36 is a light receiving signal processing circuit, 38 is a display drive circuit, 3
Reference numeral 9 is a pnp type transistor.

Claims (1)

[Claims] 1. A photoelectric switch comprising a main body, a light receiver, and a light emitter, wherein at least the light emitter is connected to the main body by two signal lines, and a pulsed light emission signal is provided in the main body. A signal generating circuit for outputting, a first pulse-shaped display signal provided in the main body portion and having a polarity opposite to that of the light projecting signal at a non-output timing of the light projecting signal, and a second peak value higher than the display signal. A display drive circuit for selectively outputting the pulsed display signal, a light projecting element which is provided in the light projector and is turned on by the light projecting signal given through the signal line, and the signal provided in the light projector. A first display element which is energized and lit through a resistor in a state where the first or second pulsed display signal is applied via a line; and the first display element provided in the projector, Second pulse table A photoelectric switch, comprising: a transistor that is turned on by a terminal voltage of the resistor when a display signal is applied; ..