JPH0352035B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement of a multi-optical axis photoelectric switch used as a detection device for stabilizing devices for various press machines, and is capable of detecting and determining changes in the blocking state of optical axes. do,
The present invention relates to a state-determining multi-optical axis photoelectric switch, which is characterized in that it can output an appropriate control signal depending on its state.

[Conventional technology and its problems]

Conventionally, various types of safety devices such as manual type, mechanical type, and light beam type have been used as safety devices to prevent accidents involving cutting of hands and fingers by press machines. Due to its structure, safety devices force the worker to lift the worker's hand as soon as the press starts operating, or a protective shutter lowers at the front of the press. It was meant to be kept away from the enemy. Therefore, press work is interrupted each time,
Not only did this lead to a decrease in work efficiency, but it also had the disadvantage that it could not be used at all, especially in press brake equipment and other operations where the operator needed to press one end of the material to be supported by hand. It was.

Therefore, in such cases, a safety device equipped with a light beam detection mechanism consisting of a large number of reflective or transmissive light emitters and receivers arranged in a straight line is used to detect the blocking state of the numerous optical axes that surround the front of the press. It was possible to detect this and suddenly stop the lowering of the upper slide of the press. The multi-optical axis photoelectric switch used for this purpose is used for example when one or more optical axes are blocked in a single optical axis detection method, or when two optical axes are adjacent to each other in a continuous two-optical axis detection method. When the above continuous light shielding condition was detected, a detection signal was immediately output and the lowering of the upper slide was suddenly stopped, so the material to be processed could be supported by hand like the press brake device mentioned above. When working, there was a problem that if the optical axis was blocked due to the thickness of the material itself or the material was inserted at an angle, the upper slide of the press would immediately stop, making it impossible to start work. It is.

[Means for solving problems]

In view of these circumstances, the present invention provides a light-blocking detection circuit that serially inputs the light-receiving codes of a plurality of sets of light emitters and receivers, and outputs a latch when one light receiver is in a light-blocking state; It is equipped with a continuous double-shading detection circuit that performs a latch output when two light receivers are in a light-shielded state, and further includes a memory circuit that performs a latch output if there is an output from the single light-shielding detection circuit within a certain period of time at the start of operation. There is. Then, an output gate circuit is provided which outputs a stop signal based on the three-input logic of one light-shielding detection circuit output, two consecutive light-shielding detection circuit outputs, and a memory circuit output, and the logic of this output gate circuit is applied to the above-mentioned memory circuit. By creating a relationship that holds true when at least one light-blocking detection circuit output occurs when there is no output, and when two consecutive light-blocking detection circuits output when there is an output from the memory circuit, the above problem can be solved. This is the solution.

[Effect]

In the above-mentioned means, the single light shielding detection circuit detects a width comparable to the width of the processed material, and the continuous double light shielding detection circuit detects a finger or the like that is wider than that. or,
The memory circuit determines that a processing material is present when one light interruption is detected at the start, and functions to prevent malfunctions caused by subsequent detection of one light interruption by the processing material. These three input logics are configured in the output gate circuit, and if at least one light blockage is detected while the memory circuit is not working, this is regarded as an abnormality and a stop signal is output, causing the memory circuit to work. Sometimes, it is only when two consecutive light interruptions are detected that an abnormality is considered, and a control function is implemented to ensure safety.

〔Example〕

Hereinafter, the state-discriminating multi-optical axis photoelectric switch of the present invention will be described in more detail based on an embodiment shown in the drawings. In FIG. For example, a light emitting/receiving unit is made up of eight sets of light emitters made of infrared light emitting diodes, 4...4 and light receivers 5...5 made of phototransistors arranged alternately in a straight line; 6 is a reflecting mirror; 3 and a reflecting mirror 6 are provided at positions facing each other in the front of the working area of the press machine, so that it is possible to determine the state of shading of the optical axis between them, and to detect the intrusion of foreign matter into the press machine. . Reference numeral 7 denotes a control unit attached to the light emitting/receiving unit 3, which has various control mechanisms including a function for determining the state of the optical axis described below.

Next, FIG. 2 is a block diagram showing an outline of the optical axis state determination function in the control unit 7, in which 11 is a reference oscillator that oscillates at a constant cycle, 12
13 is a frequency dividing circuit that divides the oscillation signal of the reference oscillator 11 to generate a control signal for determining the period of each circuit, and 13 is a projector that sequentially and continuously causes the eight projectors 4 to emit light based on the signal from the frequency dividing circuit 12. A light control circuit 14 is a light receiver 5 synchronized with the light emission of the light emitters 4...4, respectively.
This is a light reception control circuit that serially outputs the detection signal No. 5 to the subsequent stage.

Further, 15 is an amplifier circuit that amplifies the detection signal from the light reception control circuit 14, and 16 is a light-blocking detection circuit that detects the amplified detection signal when one light receiver is in a light-blocking state and outputs a signal. circuit, 17
is a continuous double-shading detection circuit that detects when adjacent light receivers are in a light-blocking state one after another and outputs a signal, and outputs only when two consecutive light-blocking states occur. Furthermore, light shielding detection circuit 1
6 and the output relationship between the continuous double light blocking detection circuit 17 is that first, when one light receiver is in a light blocking state, the single light blocking detection circuit 16 outputs a signal, and then when the next light receiver is in a light blocking state, the continuous two light blocking detection circuit 16 outputs a signal. A signal is also output from the detection circuit 17, and only the signal from the one light-blocking detection circuit 16 is output unless the following light receiver is in a light-blocking state. Both outputs remain latched until reset. The reset timing is based on one cycle of operation of eight sets of light emitters and receivers.
This is done every cycle.

Furthermore, 18 is a memory gate circuit that discriminates between the investigation command signal CH, which is issued for a certain period of time when the upper slide 1 of the press starts to descend, and the detection signal of the light-blocking detection circuit 16, and outputs the investigation command signal.
This is an AND circuit that sends a signal to the memory circuit 19 only when one light-blocking state is detected while CH is being output. 20 indicates the signal of the memory circuit 19, one signal of the light-shielding detection circuit 16, and two consecutive light-shielding detection circuits 1.
By inputting the signals in step 7, (a) when there is only a detection signal from one light shading detection circuit 16, (b) when there is a detection signal from two consecutive light shading detection circuits 17 following one light shading detection circuit 16, (h) ) When there is a signal output from the memory circuit 19 based on the output of one light-blocking detection circuit 16, and there is also a signal from two consecutive light-blocking detection circuits 17, the logic is established in the following three states and the output gate circuit outputs a signal. . In this embodiment, for the sake of explanation, the output gate circuit 20 is inverted to low when the logic is established.

Further, 21 is an integrating circuit that converts the signal from the output gate circuit 20 into a DC level, and 22 is an output circuit that outputs the converted signal to an appropriate control device such as an upper slide sudden stop device.

Note that R is a reset signal for the memory circuit 19 that is generated when the upper slide 1 is raised;
Once there is an output from 9, the output state is latched until it is reset.

Next, the details of the output gate circuit 20 are as shown in FIG.
It consists of 0b. The input of one NAND gate 20a is connected to the inverted output of the inverter of the continuous double light blocking detection circuit 17 and the output of the memory circuit 19.
The output of the light-shielding detection circuit 16 and the output of the NAND gate 20a are connected to b.

To explain the operation of each block in the above-mentioned configuration using a time chart, the section a in FIG. Therefore, the time chart is when one light blockage is detected during processing when the optical axis is not blocked, and the section b is the time chart when one light blockage is detected at the start of operation.

First, the section a will be explained. When the press starts and the upper slide 1 starts to descend, the investigation command signal CH is output for a certain period of time. At this time, the light emitting/receiving unit 3 is in the state of repeatedly detecting light blocking, but since there is no light blocking object, no signal is output from the light blocking detection circuit 16, and the logic of the memory gate circuit 18 does not hold, so the memory circuit 19 is in the low state. remains maintained. If the light shielding state is not detected after that as in the first half of section a, the output logic of the output gate circuit 20 continues to maintain high (stop signal OFF), and as the upper slide 1 descends, a series of presses is performed. The process is finished. In addition,
When the upper slide 1 is raised, a reset signal R is outputted to the memory circuit 19, and the previous state is canceled. However, when the signal from the light-shielding detection circuit 16 is output by a finger or the like after the output of the investigation command signal CH is finished as in the second half of section a, both of the two inputs of the NAND gate 20b become high. As a result, the output is reversed to low (stop signal on), so the DC component from the integrating circuit 21 drives the output circuit 22, and the lowering of the upper slide 1 is immediately stopped. In this way, the above-mentioned function (a) can be ensured through these series of movements. By the way, this is followed by the detection of two consecutive shadings (b).
However, in this case, NAND gate 2
Since the output of the storage circuit 19 for 0a is low, the output of the NAND gate 20a becomes high in any case. Therefore, in this case, the operation will be similar to (a), and the upper slide will surely stop as well.

Next, to explain section b, the investigation command signal
Since the single light shading detection circuit 16 detects the presence of the processing material when CH is output, the high latch output of the single light shading detection circuit 16 becomes one input of the ND gate 20b, and the high output of the memory circuit 19 becomes
It is input to the NAND gate 20a. On the other hand, at this time, since the continuous double light blocking detection circuit 17 is not detecting anything, an inverted output high is given to the NAND gate 20a, and the output logic of the NADN gate 20a is low. Therefore NAND gate 20
Since the output logic of b is high (stop signal off), the upper slide 1 continues to operate normally. In this case, since the output of the one-shading detection circuit 16 is in a latched state, even if the processed material is subsequently detected, it will be ignored. However, as processing progresses and your hand enters the detection area, and two or more consecutive optical axes are blocked, the continuous double light blocking detection circuit 17 is activated, and when its inverted output low is given to the NAND gate 20a, the NAND gate The output logic of 20a flips high, thereby causing NAND gate 2
The logic 0b is established and the output is inverted to low (stop signal on). As a result, the above-mentioned function (c) is achieved, and the upper slide 1 immediately stops suddenly.
It remains in a stopped state until it is restored by pressing the reset button.

〔Effect of the invention〕

As described above, according to the state-determining multi-optical axis photoelectric switch of the present invention, it not only memorizes the optical axis interruption state of the press machine when the upper slide is strongly lowered, but also determines whether or not there is a processed material at the start of operation. However, only when a wide finger or other object enters the detection area while processing the material, a signal is output to suddenly stop the upper slide from lowering due to the signal from the continuous double light-blocking detection circuit, and when there is no material to be processed, Even when a narrow object enters, a stop signal is output as an abnormality, so unlike conventional press brake equipment or bender equipment, the operator has to hold the material to be processed by hand and start the optical axis. Even when the upper slide is cut off from the upper slide, the lowering of the upper slide does not stop, increasing work efficiency.

Furthermore, if the hand position enters the detection area during work and becomes dangerous, the system detects the change in the light shielding condition and immediately issues an upper slide sudden stop signal to ensure the safety of the worker. It is expected that it will have an unprecedented effect.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the condition-discriminating multi-optical axis photoelectric switch of the present invention installed in a press machine;
The figure is a block diagram showing the outline of the circuit for the optical axis state determination function, Figure 3 is a block diagram showing the output gate circuit of Figure 2 as a logic circuit, and Figure 4 is a time chart showing the operation of the above block diagram. be. In the figure, 1... upper slide, 3... light emitting/receiving unit, 16... one light-blocking detection circuit, 17... two consecutive light-blocking detection circuits, 18... storage gate circuit, 19
...Memory circuit, 20...Output gate circuit, 22...
...Output circuit.

Claims (1)

[Claims] 1 A light interruption detection circuit that serially inputs the light reception signals of multiple sets of light emitters and receivers and outputs a latch when one light receiver is in a light shielded state;
a continuous two-shade detection circuit that performs a latch output when two light receivers are in a light-shielded state; and a memory circuit that performs a latch output if there is an output from the one light-shield detection circuit within a certain period of time at the start of operation. With,
An output gate circuit is provided which is established by the three inputs of the above-mentioned one light-shielding detection circuit output, two consecutive light-shielding detection circuit outputs, and the memory circuit output, and outputs a stop signal, and the logic of this output gate circuit is that there is no output of the above-mentioned memory circuit. A state-determining multi-optical axis characterized in that the relationship is established when at least one light-blocking detection circuit output occurs and when two consecutive light-blocking detection circuit outputs occur when there is an output of the memory circuit. Photoelectric switch.