JP4102204B2 - Area sensor controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a controller for controlling a projector and a light receiver that constitute an area sensor having a large number of optical axes.
[0002]
[Prior art]
[0003]
The area sensor is used to prevent accidents in which an operator inadvertently inserts his / her hand into a machine tool or press machine, and the part of the worker's body blocks the optical axis of the area sensor. When the area sensor detects, the operation of the machine is immediately stopped and / or an alarm is generated by the output from the area sensor.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-353986
Japanese Patent Laid-Open No. 11-353986 discloses an area sensor controller. The controller disclosed in the publication is connected to a light projector having a plurality of light projecting elements and a light receiver having a light receiving element facing each of the light projecting elements. In addition to controlling the synchronism, etc., a signal to the outside is output as a relay.
[0006]
[Problems to be solved by the invention]
The area sensor controller described above has a built-in relay as a device for relay output, but this relay has a characteristic that it has a relatively short life. In the conventional area sensor controller, the relay is replaced. To do so, it was necessary to disassemble the controller case.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an area sensor controller that can reduce relay replacement work.
[0008]
[Means for Solving the Problems]
According to the present invention, such a technical problem is
In a controller for controlling a projector and a light receiver that constitute an area sensor having a large number of optical axes,
A relay module in which a terminal board, a relay board including a relay for relay output through the terminal board and a relay drive circuit for driving the relay are detachable together;
A control board including a control circuit and a power supply circuit;
Provided on the control board and the relay board, and having an internal connector for connecting the control board and the relay board;
Power is supplied from the power terminal of the terminal block to the power circuit of the control board via the relay board and the internal connector,
The relay board is provided with a disconnection detection circuit for detecting a disconnection of a GND-side power supply line including a terminal of the internal connector between a power supply terminal of the terminal block and the power supply circuit or a contact failure of the internal connector,
This is achieved by providing an area sensor controller for forcibly turning off the relay when the disconnection detection circuit detects a disconnection of the GND terminal side power supply line or a contact failure of the internal connector. Is done.
[0009]
That is, according to the present invention, in order to replace the relay having the characteristic of relatively short life, it is only necessary to replace the relay board that is modularized together with the terminal block. Therefore, the replacement work is easy. Further, according to the present invention, power is supplied through the terminal block. Accordingly, the GND power line from the terminal block to the power circuit of the control board is disconnected, or the GND of the internal connector is connected. There is a possibility that the control signal from the control circuit always turns on the relay and is input to the relay drive circuit due to poor contact of the side power supply terminal, which may cause the relay to always be in the ON state. Provide a detection circuit to constantly monitor the disconnection of the GND power line from the terminal block to the power circuit of the control board and the contact failure of the GND power terminal of the internal connector, and immediately turn off the relay if there is an abnormality. Therefore, even if the controller breaks down, it is possible to realize fail-safe that controls the external device connected to the terminal block to the safe side.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view of an area sensor controller according to an embodiment of the present invention. The area sensor controller 1 includes a projector connector 4 for connecting a projector cable 3 extending from a projector (not shown) to the case 2 and a receiver connector 6 for connecting a receiver cable 5. A relay output terminal block 7 is also provided.
[0011]
As can be understood from FIG. 2, the terminal block 7 is detachably attached to the relay module 10 unitized together with the relay board 9 on which the relay 8 is mounted by means of screws 11. The container case 2 is fastened with bolts 12. During maintenance or when the relay 8 fails, the bolt 12 is loosened, whereby the relay module 10 can be extracted from the controller case 2 and the relay board 9 can be replaced.
[0012]
As shown in FIG. 3, the area sensor controller 1 further includes a control board 13 in the case 2, and the control board 13 and the relay board 9 are provided on both of the boards 13 and 9. Connected by the internal connector 14.
[0013]
The terminal block 7 has two power supply terminals 16 (+24 V) and 17 (0 V) that receive power supply from the power supply 15. The power that has entered the controller 1 from the power terminals 16 and 17 enters the control board 13 through the two first power lines 18 and 19 of the relay board 9 and the power terminals 20 and 21 of the internal connector 14, and is controlled. Power is supplied to the power supply circuit 24 through the second power supply lines 22 and 23 of the substrate 13, and power is supplied from the power supply circuit 24 to the control circuit 25 and the like.
[0014]
The control signal generated by the control circuit 25 enters the relay board 9 through the first signal line 26 of the control board 13 and the control terminal 27 of the internal connector 14 and is input to the relay drive circuit 29 through the second signal line 28 of the relay board 9. Then, the relay 8 is driven by the relay drive circuit 29, and the output of the relay 8 is supplied to the external device through the output terminals 20 and 31 of the terminal block 7.
[0015]
The relay substrate 9 includes a disconnection detection circuit 32, and the disconnection detection circuit 32 is connected to the first power supply lines 18 and 19 of the relay substrate 9. The disconnection detection circuit 32 detects the relay 8 via the relay drive circuit 29 when it detects that the GND terminal 21 of the internal connector 14 is in contact or the GND power supply lines 19 and 23 are disconnected. Turn it off.
[0016]
According to the embodiment shown in FIG. 3, when periodic maintenance or the relay 8 fails, it can be dealt with by pulling out the relay module 10 from the controller case 2 and replacing the relay board 9 of the relay module 10. Therefore, the workability can be improved. Further, since the power supplied through the terminal block 7 is supplied to the control board 13 via the relay board 9 and the internal connector 14, for example, when the GND-side power terminal 21 of the internal connector 14 has a poor contact, the control circuit 24 is used. It is assumed that the control signal input to the relay drive circuit 29 is always a signal for turning on the relay. However, the disconnection detection circuit 32 is provided for erroneous control of the external device due to such an abnormal state. Can be prevented. That is, when the above-described abnormal state is detected by the disconnection detection circuit 32, a disconnection detection signal is output to turn off the output of the relay drive circuit 29, thereby turning off the relay 8.
[0017]
FIG. 4 shows a specific example of the disconnection detection circuit 32. The relay board 9 is provided with a relay monitor circuit 40 in association with the relay drive circuit 29, and this relay monitor line 41 has a reference voltage of 3.3V or 0V by a Zener diode 42 provided on the control board 13. It becomes 24V in the abnormal state mentioned above. The disconnection detection circuit 32 includes a comparator 45. When the relay monitor line 41 reaches 24V, the logic is inverted and output. The output voltage is input to the base of the transistor 46, and the control signal from the control circuit 25 is relayed. The second signal line, that is, the control signal line 28 supplied to the drive circuit 29 is grounded. That is, when a disconnection is detected by the disconnection detection circuit 32, the relay 8 is forcibly turned off.
[0018]
FIG. 5 shows another specific example of the disconnection detection circuit 32. Even in the disconnection detection circuit 32 of this specific example, the disconnection detection circuit 32 includes a comparator 50. The reference voltage V1 is applied to the comparator 50, and the disconnection detection circuit 32 monitors whether or not the OV side power supply lines 19 and 23 of the relay board 9 and the control board 13 are 0V.
[0019]
For example, if the OV side power supply line 23 of the relay board 9 is not 0V due to poor contact of the GND terminal 21 of the internal connector 14 or disconnection of the OV side power supply line 19, the voltage of the B section changes and the logic of the comparator 50 changes. Inverted and outputs a disconnection detection signal to the relay drive circuit 29, and the relay drive circuit 29 forcibly turns off the relay 8 regardless of the signal on the control signal line 28.
[0020]
Here, the reference voltage V1 applied to the comparator 50 may be set to the following value. That is, the voltage of the B part at the normal time is 24v × R2 / (R1 + R2), but becomes 24v at the time of the abnormality described above. Therefore, if V1 is set so that 24v × R2 / (R1 + R2) <V1 <24v, the abnormality signal can be output to the relay drive circuit 29 by inverting the logic of the comparator 50 at the time of the abnormality described above. it can.
[Brief description of the drawings]
FIG. 1 is a perspective view of an area sensor controller according to an embodiment;
FIG. 2 is a partial perspective view showing a state where a relay module is extracted from the area sensor controller.
FIG. 3 is a block diagram of a relay board and a control board built in the area sensor controller.
FIG. 4 is a circuit diagram showing a specific example of a disconnection detection circuit incorporated in a relay board.
FIG. 5 is a circuit diagram showing another specific example of the disconnection detection circuit incorporated in the relay board.
[Explanation of symbols]
1 Area Sensor Controller 2 Controller Case 4 Emitter Connector 6 Receiver Connector 7 Terminal Block 8 Relay 9 Relay Board 10 Relay Module 13 Control Board 14 Internal Connector 15 Power Supply 29 Relay Drive Circuit 32 Disconnection Detection Circuit

Claims (2)

In a controller for controlling a projector and a light receiver that constitute an area sensor having a large number of optical axes,
A relay module in which a terminal board, a relay board including a relay for relay output through the terminal board and a relay drive circuit for driving the relay are detachable together;
A control board including a control circuit and a power supply circuit;
Provided on the control board and the relay board, and having an internal connector for connecting the control board and the relay board;
Power is supplied from the power terminal of the terminal block to the power circuit of the control board via the relay board and the internal connector,
The relay board is provided with a disconnection detection circuit for detecting a disconnection of a GND-side power supply line including a terminal of the internal connector between a power supply terminal of the terminal block and the power supply circuit or a contact failure of the internal connector,
An area sensor controller for forcibly turning off the relay when the disconnection detection circuit detects disconnection of the GND terminal side power supply line or contact failure of the internal connector. The output of the disconnection detection circuit is input to the relay drive circuit,
When a disconnection of the GND terminal side power supply line or a contact failure of the internal connector is detected by the disconnection detection circuit, a control signal line for inputting a control signal from the control circuit to the relay drive circuit is set to GND. The area sensor controller according to claim 1, wherein the output of the relay is forcibly turned off by the operation.

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