JPH07114865A - Supervisory device - Google Patents

Abstract

PURPOSE:To detect a trouble such as deciding always light transmission condition of a photoelectric switch by a simple means, by providing an abnormality detecting start means, light projection stopping means, light shield detecting means, second abnormality detection signal output means, etc. CONSTITUTION:When an abnormality detecting start means is actuated, a light projection stop means interrupts electrification to a projector or directly shields a projection port of the projector, to interrupt projection from the projector. Here, when a photoelectric switch is normal, a light receiver is placed in an noninput light condition, to decide the photoelectric switch in a shield light condition, and changing into the light shield condition is decided in a light shield detecting means, to prevent an abnormality detection signal from being output from the second abnormality detection signal output means. In the case of generating abnormality such as placing the photoelectric switch in always a light transmission condition, a light shield detecting means is decided not to have changed in a light shield condition or a condition equivalent to the light shield condition, and an abnormality detection signal is output from the second abnormality detection signal output means, to detect abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring device for detecting an intrusion into a boundary including a person or an object to be protected by a photoelectric switch.

[0002]

2. Description of the Related Art A monitoring device using a photoelectric switch is provided with a photoelectric switch around it in order to detect that a person or the like has entered a boundary including a control device such as a press machine or a protective object such as a painting. To do. Then, the intrusion into the boundary is detected by blocking the light transmission state due to the presence or passage of a person or the like between the projector and the receiver of the photoelectric switch, and the current to the control circuit of the control device such as the press machine is detected. To stop accidents to prevent accidents, and to supply an abnormality detection signal to security rooms.

The circuit portion of such a monitoring device is conventionally
For example, in the configuration as shown in FIG. 6, the light source 1a and the light receiver 1b of the photoelectric switch 1 are connected to the power source 3, respectively, and a boundary is provided between the light receiver 1b of the photoelectric switch 1 and one electrode side. A relay PHCR forming a detecting means is connected. In addition, a relay PH is provided between both electrodes of the power source 3.
The normally closed contact P1 of the CR and the relay PHESR constituting the abnormality detection signal output means are connected in series, and the relay PH
A lamp R for inputting an abnormality detection signal in parallel to display an abnormality detection is connected between both terminals of the ESR. In the figure, E1 is a normally open contact of the relay PHESR.
It is provided for self-holding of R.

A relay PHC is provided between both electrodes of the power source 3.
R normally open contact P2, stop switch 6, relay M described later
CR normally closed contact M1, operation switch 7 and relay CRA
Are connected in series. In the figure, C2 is a relay CR
A normally open contact provided for self-holding of the relay CRA. Further, an operation preparation relay MCR is connected in parallel between both terminals of the relay CRA. The relay M
A predetermined control circuit 4 is connected in parallel between both terminals of CR via a normally open contact M2 of the relay MCR, and an operation preparation lamp G is connected between both terminals of the relay MCR. There is.

The control circuit 4 is connected to the control device 5 and controls the operation of the control device. In addition, CP is a power switch, 8 is a reset switch, and R
SET indicates a reset relay. In the conventional monitoring device provided with the circuit as described above, by turning on the power switch CP, the photoelectric switches 1 are energized, that is, the light receiving signal is output from the light receiver 1b. , Relay PHCR is energized (detects light incident on the light receiver 1b)
Then, the normally closed contact P1 of the relay PHCR is opened and the normally open contact P2 thereof is closed.

When the normally closed contact P1 of the relay PHCR is opened, the relay PHCR is de-energized via the normally closed contact P1 and the normally open contact P of the relay PHCR is opened.
When the switch 2 is closed, the operation switch 7 can be energized. At this time, the relay PHESR is temporarily energized, but by pressing the reset switch 8, it is returned to the off state and the lamp R is extinguished.

Furthermore, the lamp R is not lit,
That is, the operator turns on the operation switch 7 after confirming that the photoelectric switch 1 is in the light-transmitting state.
Then, the normally open contact P2 of the relay PHCR and the relay MC
When the relay CRA is energized via the normally closed contact M1 of R, the normally open contact C2 is closed and the relay CRA is self-held in the energized state.

As a result, the relay MCR is energized, the normally open contact M2 is closed, and the control circuit 4 is supplied with current. At this time, the lamp G is turned on and it is displayed that the operation is ready. In this state, when a person or the like tries to pass between the light emitter 1a and the light receiver 1b of the photoelectric switch 1, the light transmission of the photoelectric switch 1 is interrupted, the relay PHCR is turned off, and the relay PHCR is normally closed. The contact P1 returns to the closed state and the normally open contact P2 returns to the open state.

As a result, the relay PHESR is energized via the normally open contact P1 of the relay PHCR, and the lamp R is turned on to indicate the boundary entry. At the same time, relay P
When the normally closed contact P2 of the HCR is opened, the relay CR
A becomes a non-energized state. That is, the normally open contact C2 of the relay CRA is returned to the open state, the relay MCR is de-energized, the lamp G is extinguished, and the normally open contact M2 of the relay MCR is returned to the open state to control the control circuit. The current supply to 4 is stopped, the control device 5 is stopped, and safety is secured.

In the above description, the intrusion detection means is explained as a relay circuit, but it may be constituted by a PC, a sequencer or the like.

[0011]

However, in the conventional monitoring device as described above, the disconnection of the photoelectric switch 1 is detected when the relay PHCR is in a non-conducting state, but the photoelectric switch 1 receives light. Even if a person or the like passes between the photoelectric switches 1 if contact welding occurs in the device 1b or if the relay PHCR has a failure in the on state at all times,
It is judged that the light receiver 1b is in the light entering state, that is, the photoelectric switch 1 is in the light passing state, and the invasion to the boundary is not detected.

This is a safety problem, for example, even if a person or the like passes between the projector 1a and the light receiver 1b of the photoelectric switch 1 and approaches the control device 5, the control device 5 does not stop. Or you can no longer protect the protected items. In order to inspect whether or not this failure has occurred, it is troublesome for the operator to determine whether or not the operator has to pass his or her hand between the photoelectric switches 1 to detect the intrusion.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to make it possible to detect with a simple means a failure such that the photoelectric switch is determined to be in a constantly light-transmitting state. .

[0014]

In order to achieve the above-mentioned object, a monitoring device of the present invention comprises a light emitter and a light receiver arranged at a predetermined interval, and light can pass from the light emitter to the light receiver. In addition, if there is an intrusion at the boundary between the two, it will be in a light-shielded state, and the photodetector will be supplied with a photoelectric switch that outputs a signal with and without light reception and a signal with or without light reception from the light receiver. Boundary detection means that detects that the photoelectric switch is in a light-shielded state by inputting no signal of light from the detector, and based on the boundary intrusion detection signal from the boundary detection means, receives light from the boundary intrusion detection signal. An abnormality detection signal output unit that outputs an abnormality detection signal when it is determined that the container is in a non-light-receiving state, and a start signal for detecting an abnormality of intrusion detection is output at a predetermined timing in a monitoring device. Abnormalities Detection start means, projection stop means for interrupting light emission from the projector by a start signal from the abnormality detection start means, start signal from the abnormality detection start means, and boundary intrusion detection signal or light reception from the boundary detection means Based on a signal indicating the presence or absence of light from the projector, it is detected that the photoelectric switch changes to a light blocking state or a state equivalent to the light blocking state when the light projecting from the light projector is blocked by the light projecting stop means. And a light-shielding detection means for outputting a determination signal,
Second abnormality detection signal output means for outputting an abnormality detection signal based on the determination signal from the light-shielding detection means when the photoelectric switch does not change to the light-shielded state or a state equivalent to the light-shielded state from the determination signal. It is characterized by that.

At this time, a start signal is supplied from the abnormality detection start means, and after a predetermined time has elapsed from the input of the start signal from the abnormality detection start means, the projection stop means stops the projection of light to the projector. A releasing means for releasing may be provided. Further, based on the respective signals from the abnormality detection start means, the boundary detection means, and the light shielding detection means, when the start signal is not output from the abnormality detection start means, the light receiver is in the light entering state by the signal from the boundary detection means. If it is determined that the start signal is output from the abnormality detection start means, it is determined that the photodetector is in the light receiving state by the signal from the boundary detection means, and the light is emitted by the signal from the light shielding detection means. Even if the normal detection means for outputting a normal signal is provided only when it is determined that the photoelectric switch has changed to the light-shielded state or a state equivalent to the light-shielded state when the light emission from the projector is blocked by the stop means Good.

Further, a photoelectric switch is arranged at a predetermined position of a predetermined control device, and a normal signal indicating that the photoelectric switch is in a light-transmitting state is supplied from a monitoring device to a current to a control circuit of the control device. In the monitoring device provided with the power supply means for performing only in the case of the above, the abnormality detection starting means may be interlocked with the switch for starting the current supply to the control circuit.

[0017]

When the abnormality detection starting means is actuated, the light emission stopping means cuts off the power supply to the light projector or directly blocks the light projection port of the light projector to block the light projection from the light projector.
At this time, if the photoelectric switch is normal, the light receiver is in a non-light-entering state, and the photoelectric switch is determined to be in a light-shielded state.
The change in the light-shielded state is determined by the light-shielding detection means, and the abnormality detection signal is not output from the second abnormality detection signal output means.

On the other hand, when the photoelectric switch is constantly in a light-transmitting state due to contact welding or the like, or when an abnormality occurs such that the boundary detecting means constantly inputs a light-incident signal from the light receiver. In addition, the light-shielding detection means determines that the light-shielded state or the state equivalent to the light-shielded state has not changed, and the abnormality detection signal is output from the second abnormality detection signal output means to detect the abnormality.

When this work is completed, the reset switch or the like is pushed to release the light emission interruption by the light emission stopping means.
At this time, by providing the releasing means, the light projection by the light projector is automatically restarted. Further, by providing the normality detecting means, the normality signal is output only when the abnormality is not detected.

Further, according to the structure described in claim 4, every time when the initial drive of the control device is started every morning or the like, the presence or absence of abnormality such as contact welding of the photoelectric switch is automatically inspected, and abnormality is detected. When is detected, the control device is automatically prevented from driving, and if no abnormality is detected, current supply to the control circuit is started as in the conventional case.

[0021]

Embodiments of the present invention will be described with reference to the drawings.
First, the configuration will be described. As shown in FIG. 4, the light emitter 1a and the light receiver 1b of the photoelectric switch 1 are arranged to face each other with a predetermined gap, and a plurality of light beams 2 are directed from the light emitter 1a to the light receiver 1b. Can be projected, and the photoelectric switch 1 detects the light-transmitting state by the light beam 2 entering the light receiver 1b side, and the light beam 2 moves to the light receiver 1b side. When the light is not received, it is possible to detect the light blocking state, that is, the boundary intrusion.

The light projector 1a and the light receiver 1b are respectively connected to a power source 3 as shown in FIG. A relay PHCR forming a boundary detection means is connected between the photodetector 1b and one electrode of the power supply 3, and the relay PHCR is energized when the photodetector 1b detects light entering. The signal with light is supplied at, and the non-signal with no light is supplied to the relay PHCR due to the non-conduction state.

Further, a normally-closed contact OFF1 of a relay OFFCR forming a part of the light emission stopping means is provided between the light projector 1a and the power source 3. Further, a normally open contact T1 of the relay T1, a normally closed contact P1 of a relay PHCR that controls a boundary detection signal, and a relay PHESR that constitutes an abnormality detection signal output means are connected in series between both terminals of the power supply 3. .

A normally closed contact C1 of the relay CRA is connected in parallel between both terminals of the normally open contact T1 of the relay T, and the normally open contact T1 and the relay PHCR of the relay T connected in series are connected. A normally open contact E1 of the relay PHESR and a normally closed contact RS1 of the relay RSET are connected in series in parallel with the normally closed contact P1. In addition, the relay P
A boundary abnormality indication lamp R1 which is turned on by energization (abnormality detection signal input) is connected in parallel between both contacts of the HESR.

Further, a stop switch 6, a normally closed contact OK1 of the relay OKCR1, a normally closed contact M1 of the relay MCR1, an operation switch 7 also serving as an abnormality detection starting means, and a relay CRA are connected in series between the power sources 3. . The normally-closed contacts OK1 and M1 are incorporated for fail-safe when the relay OKCR and the relay MCR fail.

The relay OKC connected in series is also provided.
R normally closed contact OK1, relay MCR normally closed contact M1 and operation switch 7 in parallel with the relay CRA normally open contact C2
Is provided. Further, a relay T constituting a releasing means is connected in parallel between both terminals of the relay CRA. The relay T has a timer and is set to be in an actual energized state after a predetermined time (0.5 seconds in this embodiment).

In addition, the normally closed contact T3 of the relay T3, the normally closed contact OK2 of the relay OKCR, and the relay OFFC constituting the light emission starting means are arranged in parallel between both terminals of the relay T.
R, a relay OKCR forming the normally closed contact P2 of the relay PHCR and the light shielding detection means, a normally open contact T2 of the relay T2, a normally closed contact OK4 of the relay OKCR, and a relay forming the second abnormality detection signal output means. NGCR and normally open contact OK5 of relay OKCR that constitutes the normal detection means, normally open contact P3 of relay PHCR, relay NG
The normally closed contact NG2 of the CR and the relay MCR forming the normality detecting means are connected in series.

The normally closed contact P2 of the relay PHCR is also provided.
In parallel between both terminals of the relay OKCR normally open contact OK3
Are connected for self-holding. The normally open contact T2 of the relay T and the normally closed contact OK4 of the relay OKCR connected in series are connected in parallel with the normally open contact NG1 of the relay NGCR.
And a normally closed contact RS2 of the relay RSET are connected in series.

Further, between both terminals of the relay NGCR,
A lamp R2 for displaying an abnormality, which is turned on by inputting an energized state (abnormality detection signal), is connected in parallel. A lamp G for operation preparation is connected in parallel between both terminals of the relay MCR. Further, the control circuit 4 is connected in parallel between both terminals of the relay CRA via a normally-open contact M2 of a relay MCR that constitutes a part of power supply means that is closed when the photoelectric switch 1 is in a light-transmitting state. Are connected.

The control circuit 4 is connected to a control device 5 such as a welding robot or a rolling line, and around the control device 5,
As shown in FIG. 4, the photoelectric switch 1 is arranged. Although only one photoelectric switch 1 is illustrated in FIG. 4, of course, a plurality of photoelectric switches 1 may be set. In FIG. 1, CP is a power switch, 8 is a reset switch, and R is
SET represents a reset relay.

As shown in FIG. 3A, when the power switch CP is turned on, the projector 1a is energized via the normally-closed contact OFF1 of the relay OFFCR. A beam of light 2 from the projector 1a
Is projected toward the light receiver 1b and the beam 2 is received by the light receiver 1b.
Light is incident on b, so that the photoelectric switch 1 is in a light-transmitting state.

When the light beam 2 is incident on the photodetector 1b, the relay PHCR is turned on (energized signal is supplied) by turning on the relay PHCR. As a result, the normally closed contacts P1, P2 of the relay PHCR are opened and the normally open contact P3 thereof is closed. At the same time, the normally closed contact C1 of the relay CRA and the relay PH
The relay PHESR is energized via the normally closed contact of the CR, and the relay PHESR is temporarily turned on.
Return to the off state by the relet button.

In this state, it is confirmed that the lamp R1 is off, and when the operator turns on the operation switch 7, the stop switch 6 and the normally-closed contact OK of the relay OKCR are OK.
1, the relay CRA is energized through the normally closed contact M1 of the relay MCR and the operation switch 7, the relay CRA is turned on, and the normally open contact C2 of the relay CRA is closed and the relay CRA is turned on. The self-holding state is maintained and the normally closed contact C1 is opened.

At the same time, the relay T is energized and the timer starts to operate, and the normally closed contact T3 of the relay T3 and the relay O
The relay OFFCR is energized via the normally closed contact OK2 of the KCR to be turned on. This turns off the relay
The normally closed contact OFF1 of the CR is opened and the projector 1a is de-energized, so that the projection of light from the projector 1a is blocked.

At this time, if the photoelectric switch 1 is normal, there is no light entering the light receiver 1b, so the relay PHCR is in the non-energized state, that is, the off state, and the normally closed contacts P1 and P2 of the relay PHCR are closed. The normally open contact P3 returns to the open state. As a result, the normally closed contact P of the relay PHCR is
The relay OKCR is energized via 2 to be turned on, the normally open contact OK3 of the relay OKCR is closed, the relay OKCR is self-held in the on state, and the normally open contact OK5 is closed. The normally closed contacts OK1, OK2, OK4 of the relay OKCR are opened.

Normally closed contacts OK1, OK of the relay OKCR
When the relays 2, 2 and 4 are opened, the relay OFFCR is de-energized and returns to the off state.
The normally closed contact OFF1 of the FCR is closed, and a current again flows through the light emitter 1a, the light emitter 1a and the light receiver 1b are in the light-transmitting state, the relay PHCR is turned on again, and the normally open contact P3 of the relay PHCR is turned on. Normally closed contact P1,
P2 is opened.

At the same time, the relay OKCR normally open contact is OK.
5, relay PHCR normally open contact P3 and relay NGCR
The relay MCR is energized via the normally closed contact NG2 of
The relay MCR is turned on, the normally open contact M2 of the relay MCR is closed, and the normally closed contact M1 thereof is open. The normally closed contact OK4 of the relay OKCR is opened, so that the relay NGCR and the lamp R2 are kept in the non-energized state, and the lamp R2 is not turned on.

As a result, the lamp G is turned on and the control circuit 4 is energized. In this state, when 0.5 seconds elapses after the timer of the relay T is energized, the normally open contacts T1 and T2 of the relay T are closed and the normally closed contact T3 is opened. At this time, even if the normally open contact T2 of the relay T is in the closed state, the normally closed contact OK4 of the relay OKCR is in the open state, so the relay NGCR is held in the non-energized state and turned off. ing.

On the other hand, if the photoelectric switch 1 is always in a light-shielded state due to a disconnection or the like, the power source 3 switch C
Even if P is turned on, the relay PHCR remains in the non-energized state and is kept in the off state. At the same time, relay CRA
The relay PHESR is energized and turned on via the normally closed contact C1 and the normally closed contact P1 of the relay PHCR, the normally open contact E1 of the relay PHESR is closed, and the lamp R1 is turned on.

In this state, even if the reset switch 8 is pushed to open the normally closed contact RS1 of the relay RSET, the relay PHESR remains energized through the normally closed contact C1 of the relay CRA and the normally closed contact P1 of the relay PHCR. At the same time, the lamp R1 remains lit. As a result, the operator becomes aware of an abnormality such as disconnection of the photoelectric switch 1.

If the operator turns on the operation switch 7 in the above state, the relay CRA is energized and turned on, and the normally open contact C2 of the relay CRA is closed to energize the relay CRA. The state is self-maintained and the normally closed contact C2 of the relay CRA is opened. At this time, the relay PHESR is connected through the normally open contact E1 of the relay PHESR and the normally closed contact RS1 of the relay RSET.
Since the lamp R1 is kept energized, the lamp R1 is kept in a lighting state, and after 0.5 seconds, the normally open contact T1 of the relay T is closed and the reset switch 8 is pressed. However, the relay PHESR and the lamp R1 are kept energized.

Further, since the relay PHCR is in the OFF state, the normally open contact P3 of the relay PHCR remains in the open state, so that the relay MCR is kept in the non-energized state and the relay MCR is normally opened. The contact M2 is maintained in the open state, and the supply of current to the control circuit 4 is avoided. On the other hand, if the contact welding occurs and the photoelectric switch 1 is always in the light-transmitting state and the light receiver 1b is in the erroneous detection state, the power source 3
The lamp R1 does not light even if the switch CP is turned on.

In this state, as shown in FIG. 3B, when the operator turns on the operation switch 7, the relay CR
A is energized to be in an ON state, and the normally-open contact C2 of the relay CRA is in an open state, so that energization to the relay CRA is self-maintained. At the same time, the relay T is energized to activate the timer, and the normally closed contact T3 of the relay T3 and the relay OKC
The relay OFFCR is energized through the normally closed contact OK2 of R, the normally closed contact OFF1 of the relay OFFCR is turned on, the normally closed contact OFF1 of the relay OFFCR is opened, and the projector 1a side of the photoelectric switch 1 is not turned on. It is energized.

However, since the photodetector 1b erroneously detects that the light is entering, the relay PHCR does not return to the off state, the normally closed contact P2 of the relay PHCR is held in the open state, and the relay OKCR is turned off. Held in a state. Then, 0.
After 5 seconds, the normally closed contact T3 of the relay T is opened and the normally open contacts T1 and T2 are closed.

As a result, the normally open contact T2 of the relay T2
Relay NGC via normally closed contact OK4 of relay OKCR
The R and the lamp R2 are energized and turned on, the normally closed contact NG2 of the relay NGCR is opened and the normally open contact NG1 is closed, and the lamp R2 is turned on to indicate that there is an abnormality. At this time, since the normally open contact OK5 of the relay OKCR is in the open state and the normally closed contact NG2 of the relay NGCR is in the open state, the relay MCR is kept in the non-energized state and remains in the off state.
Since the normally open contact M2 of 1 is held in the open state, the current is not supplied to the control circuit 4.

In this circuit, the relay CRA,
Even if any one of T, OFFCR, OKCR, NGCR, and MCR fails in the ON state or the OFF state, the control circuit 4
Since it is not energized to, the circuit is fail-safe capable. When this circuit is incorporated in a sequencer, a circuit as shown in FIG. 5 is obtained. In addition, when the photoelectric switch 1 is normal and the control device 4 is in an operating state due to the supply of current to the control circuit 4,
When a person or the like approaches the control device 5 and enters a boundary between the photoelectric switches 1, the photoelectric switch 1 is shielded and the relay PHCR is returned to the off state.

Then, the normally closed contact P1 of the relay PHCR.
Returns to the closed state. Accordingly, the relay P is connected via the normally open contact T1 of the relay T1 and the normally closed contact P1 of the relay PHCR.
The HESR and lamp R1 are energized to indicate intrusion. At the same time, the normally open contact P2 of the relay PHCR
Is returned to the open state, the relay MCR is turned off and returns to OFF, the control circuit 4 is turned off, and the control device 5 is stopped.

As a result, the control device 5 for the press machine or the like
When a person or the like approaches the vehicle, the control device 5 is stopped and safety is ensured. As described above, in the monitoring device of the present embodiment, a failure in the photoelectric switch 1 that is always in a non-energized state due to a disconnection or the like is detected, and the photoelectric switch 1 is activated when the control device 5 is started up. It is also possible to detect a failure in which the contact is always energized due to contact welding or the like.

In the above embodiment, the timer of the relay T1 is set to 0.5 seconds because the photoelectric switch 1 can be switched to the light-shielding state and the projector 1
This is to shorten the time for which the light projected from a is blocked. Therefore,
The timer may be set to 0.5 seconds or more. In the above-described embodiment, the relay T constituting the releasing means is provided to automatically restore the light projecting state of the projector 1a. However, a switch for recovery or the like is additionally provided to the projector 1a.
You may cancel the light emission cut-off state of a.

Further, in the above embodiment, the operation switch 7 also serves as the abnormality detection starting means, but a switch may be separately provided for the abnormality detection starting means. Further, in the above embodiment, when the abnormality is not detected by being connected to the control circuit 4 via the normally open contact M2 of the relay MCR,
Although the current is automatically set to be supplied to the control circuit 4, the operator pushes the switch again by providing a second operation start switch instead of the normally open contact M2 of the relay MCR. Alternatively, the control circuit 4 may be configured to start when it is turned off.

In the above embodiment, the case where the photoelectric switch 1 is one is shown, but it may be applied to the case where a plurality of photoelectric switches 1 are arranged. In this case, it suffices to set the circuits of the portions X1 and X2 in FIG. Further, the monitoring device of the above embodiment is linked to the control device 5, but the photoelectric switch 1
When installed and used at the entrance of a room or in front of a painting or the like, the normal signal supplied through the normally open contact M2 of the relay MCR may be supplied to an alarm buzzer or the like.

Further, in the above-mentioned embodiment, the signal indicating whether or not the light is received from the photodetector 1b from the relay PHCR through the normally closed contact P2 (energized / non-energized state) is input to the relay OKCR. A signal indicating whether light is incident may be directly input to the relay OKCR from the device 1b. However, in this case,
A failure such as contact welding occurring in the relay PHCR which is the boundary detection means is not detected.

Further, in the above-mentioned embodiment, the light is cut off by shutting off the power supply to the light projector 1a, but it is possible to temporarily block the light projecting port of the light projector 1a with a shield which can be opened and closed. The light emission stopping means may be configured. Further, in the above-described embodiment, the light emitter 1a and the light receiver 1b which form the photoelectric switch are arranged so as to face each other, and the light beam 2 from the light emitter 1a is directly incident on the light receiver 1b. Bowl 1
b not facing each other, the light beam 2
May be arranged so that light can enter the light receiver 1b side.

[0054]

As described above, in the monitoring device of the present invention, an abnormality in which the photoelectric switch is always in the light-transmitting state and an abnormality in which the boundary detecting means is always on are
It becomes possible to detect easily. At this time, by providing the releasing means, the light emission blocking state of the light emitting device performed for detecting the abnormality can be automatically released.

Further, by providing the normality detecting means,
The normal signal will be output only when no abnormality is detected. Further, when the monitoring device has a photoelectric switch arranged around a predetermined control device and the monitoring device is interlocked with the operation of the control device, the abnormality detection start means controls the current supply of the control device. If it is linked to the switch to start, the abnormality inspection is automatically performed every morning or immediately before the control device is started, and if an abnormality is detected, the current supply to the control device is automatically disabled. Become.

[Brief description of drawings]

FIG. 1 is a claim configuration diagram according to the present invention.

FIG. 2 is a schematic circuit diagram showing a monitoring device according to an embodiment of the present invention.

3A and 3B are diagrams showing the progress of the on / off state of each relay in the monitoring device of the embodiment according to the present invention, wherein FIG. 3A shows the progress at the normal time and FIG. 3B shows the progress at the abnormal time. .

FIG. 4 is a schematic configuration diagram showing a monitoring device according to an embodiment of the present invention.

FIG. 5 is a schematic circuit diagram showing a monitoring device according to another embodiment of the present invention.

FIG. 6 is a schematic circuit diagram showing a conventional monitoring device.

[Explanation of symbols]

 1 Photoelectric Switch 1a Emitter 1b Light Receiver 2 Light Beam 3 Power Supply 4 Control Circuit 5 Control Device 7 Operation Switch (Abnormality Detection Starting Means) 8 Reset Switch PHCR Relay (Boundary Detection Means) PHESR Relay (Abnormality Detection Signal Output Means) CRA Relay T Relay (release means) OFFCR relay (light emission stop means) OKCR relay (light-shielding detection means) NGCR relay (second abnormality detection signal output means) MCR relay RSET relay R1 abnormality display lamp R2 abnormality display lamp

Claims (4)

[Claims] 1. A light emitter and a light receiver which are arranged at a predetermined interval. Light can pass from the light emitter to the light receiver, and when there is a boundary between the light emitter and the light receiver, the light shield state occurs and the light receiver. Is a photoelectric switch that outputs a signal with and without light input, and a signal indicating whether or not light is received from the light receiver. Based on the boundary intrusion detection signal from the boundary detection means and the boundary intrusion detection signal, when the light receiver is determined to be in the non-light-receiving state from the boundary intrusion detection signal, an abnormality detection signal is output. In a monitoring device provided with an abnormality detection signal output means for outputting, an abnormality detection start means for outputting a start signal for detecting an abnormality of intrusion detection at a predetermined timing, and a projector by a start signal from the abnormality detection start means Based on the light emission stop means for blocking the light emission from these sources, the start signal from the abnormality detection start means, and the boundary intrusion detection signal from the boundary detection means or the light reception presence / absence signal from the light receiver. From the light-shielding detector, which detects that the photoelectric switch changes to a light-shielded state or a state equivalent to the light-shielded state when the light-stopping unit shuts off the light emitted from the projector, Second abnormality detection signal output means for outputting an abnormality detection signal when the photoelectric switch does not change to a light-shielded state or a state equivalent to the light-shielded state based on the determination signal of And monitoring equipment. 2. The interruption signal from the projection stop means is released after a predetermined time has elapsed since the start signal was supplied from the abnormality detection start means and the start signal from the abnormality detection start means was input. 2. The monitoring device according to claim 1, further comprising a releasing means for performing the operation. 3. When the start signal is not output from the abnormality detection start means on the basis of the respective signals from the abnormality detection start means, the boundary detection means, and the light-shielding detection means, the photodetector is activated by the signal from the boundary detection means. When it is determined that the light receiving state is detected and when the start signal is output from the abnormality detection starting means, it is determined that the photodetector is in the light receiving state based on the signal from the boundary detecting means, and the signal from the light shielding detecting means. The normal detection means that outputs a normal signal only when it is determined that the photoelectric switch has changed to the light-shielding state or a state equivalent to the light-shielding state when the light emission from the light-emitter is blocked by the light-projection stopping means by The monitoring device according to claim 2, further comprising: 4. A photoelectric switch is arranged at a predetermined position of a predetermined control device to supply a current to a control circuit of the control device.
In a monitoring device provided with a power supply means for performing only when a normal signal indicating a light-transmitting state is supplied to the photoelectric switch from the monitoring device, the abnormality detection starting means is a switch for starting current supply to the control circuit. The monitoring device according to claim 3, wherein the monitoring device is interlocked with.