JPH0695448B2 - Photoelectric switch - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric switch, and more particularly, to a device for transmitting the timing of light emission when a plurality of photoelectric switches driven by a modulation method are used in parallel. Regarding

[Prior art]

Conventionally, when a plurality of photoelectric switches using modulated light are connected in series and used, particularly in a transmission type photoelectric switch, mutual interference occurs when the projectors emit light simultaneously. That is, light enters from the other light projector to the light receiver paired with the light projector, and the light receiver operates erroneously.

Therefore, conventionally, it is necessary to intentionally shift or match the light emission timing of each projector. In this case, a plurality of photoelectric switches are electrically connected to each other by a cable or the like to adjust the light emission timing. .

For this reason, not only the number of cables increases, but also the wiring becomes complicated, and wiring errors are more likely to occur.

[Object of the Invention]

In view of such conventional problems, an object of the present invention is to perform transmission of light emission timing between each photoelectric switch without using electrical wiring.

[Outline of Invention]

In order to achieve the object, the present invention provides a transmission light projecting element and a light receiving element in addition to a switching light projecting element and a light receiving element in a case of a photoelectric switch, and further provides a case transmitting and light receiving element. A light transmitting portion is provided in the facing portion. Then, when a plurality of photoelectric switches are connected in series, among the adjacent photoelectric switches, the transmission light projecting element of one photoelectric switch and the light receiving element for transmission of the other photoelectric switch are optically opposed to each other. One of the photoelectric switches adjacent to the photoelectric switch is transmitted to the other photoelectric switch.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

That is, in FIG. 1, the housing 2 is formed of a translucent material and has openings in the first wall portion 5 and the second wall portion 6 that intersects with the first wall portion. The opening is covered with a translucent cover 3, and the cover and the housing 2 form a case 1. The lens plate 7 is attached to the opening formed in the first wall portion 5. Further, a holder 8 made of a non-translucent material is housed in the case 1 and is in contact with the lens plate 7 on its inner surface. Then, the light emitting element 11 or the light receiving element 12 for switching is held in this holder. A printed circuit board 13 is housed in the case 1. The substrate is arranged along the longitudinal direction of the case 1 and faces the second wall portion 6 and the third wall portion 9 of the case,
It is connected to the holder 8 at one end and is electrically connected to the light projecting element 11 or the light receiving element 12. Case 1
In addition to the light-transmitting element 11 and the light-receiving element 12 for switching, a light-transmitting element 15 and a light-receiving element 16 for signal transmission are housed therein, among which the light-emitting element 15 is on one surface of the printed circuit board 13. , Is fixed so as to face the third wall portion 9 of the case 1, and the light receiving element 16 is fixed to the other surface of the printed circuit board 13 so as to face the second wall portion 6 of the case 1. .

The light projecting element 11 for switching is driven by the modulation method, and accordingly emits light with a predetermined modulation pulse. The signal transmitting light projecting element 15 is interlocked with the switching light projecting element 11 via the printed circuit board 13.

The case 1 does not have to be formed of a translucent material over the whole, and for example, only a portion facing the light projecting element 15 for signal transmission and the light receiving element 16 is made translucent by two-color molding, or 1 is molded with an opaque material,
A light-transmitting cap or lens may be attached to a portion facing the signal transmitting light emitting element 15 and the light receiving element 16.

In addition, the light transmitting element 15 and the light receiving element 16 for signal transmission are on both walls.
It is desirable to install them close to 9 and 6, respectively, but this is not the case if the signal level is sufficient.

Further, the cable 17 is introduced into the case 1 through the other end of the case 1, that is, the fourth wall 10 facing the first wall 5, and is connected to the printed circuit board 13.

A plurality of photoelectric switches SW having such a structure are prepared and connected as shown in FIG. 2, that is, one photoelectric switch SW1 is provided with a third wall portion 9 and a next photoelectric switch SW2 is provided with a second electrode. The wall portion 6, that is, the cover 3 is overlapped, and the next photoelectric switch SW is further attached to the third wall portion 9 of this photoelectric switch.
The second wall portions 3 of 3 are overlapped, and thereafter, they are similarly overlapped and connected to each other by a bolt (not shown) or the like. As a result, the first light emitting element 1 for signal transmission of the photoelectric switch SW1
5 and the photodetector 16 for signal transmission of the next photoelectric switch SW2,
Further, the signal transmitting light emitting element 15 of the photoelectric switch and the signal transmitting light receiving element 16 of the next photoelectric switch SW3 are aligned with each other and optically oppose each other.

FIG. 3 is a circuit diagram of an essential part of two photoelectric switches adjacent to each other in the photoelectric switches in the connected state shown in FIG. 2, and the first photoelectric switch SW1 has an oscillation circuit 21. The output terminal of the circuit is connected to the base of the output transistor 22, and the resistor 25 is connected between the emitter of this transistor and the ground terminal 24 of the power supply. Also the positive terminal of the power supply
A light projecting element 11 for switching and a light projecting element 15 for signal transmission corresponding to the light receiving element are connected in series between the collector of 23 and the transistor 22.

On the other hand, the second photoelectric switch SW2 is connected to the first photoelectric switch SW1.
The oscillator circuit 21 is replaced with a comparator 26.
A light receiving element 16 for signal transmission, for example, a photodiode and a resistor 27 are connected in series between the positive terminal 23 of the power source and the ground terminal. The connection point between the resistor and the light receiving element 16 is connected to one input terminal of the comparator 26, and the other terminal of the comparator is connected to the reference voltage source 28 for giving a reference voltage. Further, the base of the transistor 22 is connected to the output terminal of the comparator 26, and the emitter of this transistor is connected to the ground terminal 24 of the power source via the resistor 25. Similarly to the first photoelectric switch SW1, between the positive terminal 23 of the power source and the emitter of the transistor 22, a light emitting element and a corresponding light projecting element 11 for switching and a light projecting element 15 for signal transmission are connected in series. It

If the photoelectric switch shown in FIG. 1 is a transmissive type, the light emitted from the projector P reaches a light receiver R provided separately from the projector as shown in FIG. If the detected object 30 is present during that time, the light does not reach the light receiver R. As a result, the presence or absence of the detected object 30 is detected.

When the photoelectric switch shown in FIG. 1 is of a reflection type, the light emitted from the projecting element for switching hits the object to be detected, and is reflected by this to reach the light receiving element 12 for switching. It

When the photoelectric switch shown in FIG. 1 is of the coaxial reflection type, the light emitted from the light projecting element 11 for switching hits a reflecting plate (not shown) and is reflected by the reflecting plate (not shown). Although the light reaches the light receiving element 12 for light, the light does not reach the light receiving element 12 when there is an object to be detected in the meantime, whereby the presence or absence of the object to be detected can be detected.

At this time, the light projecting element 11 for switching emits light with a predetermined modulation pulse, and therefore the light projecting element 15 for signal transmission which is linked with this also emits light with the same modulation pulse.

The operation of the photoelectric switch shown in FIG. 2 will be described below with reference to FIGS. 3 and 4.

That is, the first light emitting element 1 for signal transmission of the photoelectric switch SW1
The light emitted from 5 passes through the second wall portion 6 of the case 1 and the third wall portion 9 of the next photoelectric switch SW2 and reaches the light receiving element 16 for signal transmission of this switch. As a result, the light projecting element 11 for switching of the next photoelectric switch SW2 emits the same modulated light as the light projecting element 11 of the first photoelectric switch SW1.
Similarly, the light projecting element 11 of the next photoelectric switch SW3 emits light with the same modulation pulse as that of the light projecting element 11 of the photoelectric switch SW2 of the previous stage.

The operation timing of each photoelectric switch at this time is as shown in FIG.

When a delay circuit 29 is provided between the comparator 26 and the transistor 22 of the next photoelectric switch SW1 as shown in FIG. 5, the operation timing of those photoelectric switches is as shown in FIG. .

〔The invention's effect〕

As described above, the present invention is provided with the light projecting element 11 or the light receiving element 12 for switching on the first wall portion 5 of the case 1, intersects with the first wall portion 5 and is opposed to the other side of the case 1. Since the light emitting element 15 and the light receiving element 16 for signal transmission are arranged so as to face the second wall portion 6 and the third wall portion 9, respectively, when a plurality of photoelectric switches are connected in series. There is an effect that signals can be transmitted between the photoelectric switches without using dedicated wiring.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a photoelectric switch according to the present invention, FIG. 2 is a vertical sectional view showing a state where a plurality of photoelectric switches shown in FIG. 1 are connected in series, and FIG. 3 is shown in FIG. Of the photoelectric switches, a circuit diagram of essential parts showing signal transmission states of two photoelectric switches, FIG. 4 is a timing chart showing operation timings in FIG. 3, and FIG. 5 is an essential part showing a modified example of FIG. The circuit diagram and FIG. 6 are timing charts showing the operation timing in FIG. 1 ... Case, 2 ... Housing, 3 ... Cover, 5 ...
... first wall portion, 6 ... second wall portion, 7 ... lens plate, 8
...... Holder, 9 ... Third wall, 10 ... Fourth wall,
11 ... Emitter element, 12 ... Receiving element, 13 ... Printed circuit board, 15 ... Emitter element, 16 ... Receiving element, 17 ... Cable, 21 ... Oscillation circuit, 22 ... Transistor, 23 …… Positive terminal, 24 …… Ground terminal, 25 …… Resistance, 26 …… Comparator, 27 …… Resistance, 28 …… Reference voltage source, 29 …… Delay circuit, 30 …… Detected object.

Claims (1)

[Claims] 1. A case (1) accommodates a light projecting element (11) for switching or a light receiving element (12) for switching, and the element is housed in the first wall portion (5) of the case (1). In the case (1), a light-transmitting element (15) for signal transmission and a light-transmitting element (15) for signal transmission interlocking with the light-emitting element (11) or the light-receiving element (12) are disposed in the case (1). A second wall portion (6) and a third wall which accommodate the light receiving element (16) and which face each other of the case (1) intersecting the first wall portion (5). And the light emitting element (1) for signal transmission at least on the both wall portions.
5) and the light receiving element (1
6) is provided with a translucent portion in a portion facing the driving element for driving the switching light projecting element (11) by a modulation method, and a plurality of the cases (1) are prepared, and one of the cases adjacent to each other is provided. The second wall portion (6) and the other third wall portion (9) are successively arranged so as to sequentially overlap with each other, and the signal transmitting light emitting element (15) in one case and the other case A photoelectric switch characterized in that the light receiving element (16) for signal transmission therein is optically connected to each other.