JPH065169A - Wide directional angle photoelectric switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a photoelectric switch that can obtain a sufficiently wide and stable detection area even with one unit, and can realize space saving and low cost. In a photoelectric switch including a light projector 1 for emitting light and a light receiver 2 for receiving light from the light projector 1,
Inside the light projector 1, 11 LEDs (L
1 to L11) were radially arranged by changing the light emission angle. The detection distance from the projector 1 becomes uniform, and a stable detection area having a wide directivity angle can be obtained.

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 wide directional angle.

[0002]

[Prior Art] With the recent labor saving and automation of industry,
Factory automation of product assembly is making further progress. For example, in a production line of an industrial machine such as an automobile or a machine tool, an unmanned vehicle such as an automated guided vehicle that unmannedly conveys a product-related article (a work, a part, a semi-finished product, etc.) to a predetermined place in a factory. The car is in use.

Such an unmanned vehicle is generally equipped with a photoelectric switch for preventing a rear-end collision between the unmanned vehicles. The photoelectric switch is composed of a light emitter that emits light and a light receiver that receives light from the light emitter. In an unmanned vehicle, the light emitter is usually attached to the rear part and the light receiver is attached to the front part. Then, the light emitted from the projector of the front unmanned vehicle is received by the light receiver of the rear unmanned vehicle, and when the rear vehicle is too close to the front vehicle, that is, the inter-vehicle distance between the front and rear vehicles is reduced to within a predetermined detection area. Then, the rear vehicle stops or decelerates to avoid a rear-end collision.

By the way, a normal photoelectric switch having a wide directional angle has a directional angle of about 90 °, and if the unmanned vehicle only travels straight, there is no danger of a rear-end collision even at such a directional angle. However, an unmanned vehicle may curve in addition to going straight, and if the front and rear vehicles curve in the same direction with a short inter-vehicle distance, the light receiver of the following vehicle may appear even if the vehicle behind is approaching. It may not be able to receive the light from the projector of the vehicle ahead, and may collide at a curve. To prevent this, a plurality of photoelectric switches are used to widen the directional angle. For example, the projector and the receiver of the three photoelectric switches may be arranged in parallel by changing the light emission angle to widen the detectable directivity angle.

[0005]

FIG. 13 shows a detection area obtained when three photoelectric switches are used. In this case, the projectors 91 and 92 of the left and right photoelectric switches are different from the projector 90 of the central photoelectric switch in the emission direction of light, so that the detection area C (hatched portion) of approximately 150 ° can be covered. it can. However, as can be seen from the figure, the detection distance in the detection area C is not uniform, and there is a region X with a short detection distance in part due to the angle from the projector, so stable detection cannot be performed. In addition, since a plurality of photoelectric switches (here, three) are used, it is necessary to secure a large space for mounting the photoelectric switches. Moreover, in addition to a plurality of photoelectric switches, a main circuit for controlling these photoelectric switches is required, which increases the cost.

In addition, in order to extend the detection distance only in a part of the detection area (for example, the area in the front direction), that is, in order to obtain a detection area capable of detecting both near and far, two photoelectric switches are used. is there. Figure 1 shows the detection area in this case.
4 shows. Here, short-distance and long-distance photoelectric switches are used, and the respective projectors 95 and 96 are arranged at the same position. As a result, the detection area is a combination of a fan-shaped short-distance area D and a long-distance area E extending forward with a narrow directional angle as shown in the figure. However, also in this case, since two photoelectric switches are used in the distance and near, the mounting space becomes large and the cost becomes high.

Therefore, paying attention to the above-mentioned conventional problems, the first object of the present invention is to provide a photoelectric switch which can obtain a sufficiently wide and stable detection area even with one unit, and can realize space saving and low cost. To provide. It is a second object of the present invention to provide a photoelectric switch that can obtain both the near and far detection areas even with one unit, and can realize space saving and low cost.

[0008]

The first object is a wide directional photoelectric switch according to claim 1 of the present invention, and the second object is a wide directional photoelectric switch according to claim 2 of the present invention. Are achieved respectively. That is, claim 1
The described photoelectric switch, in the conventional photoelectric switch,
It is characterized in that a plurality of light projecting elements are radially arranged to form a light projector by changing a light emitting angle. or,
A photoelectric switch according to a second aspect of the present invention is the photoelectric switch according to the first aspect, further characterized in that the projector further includes means for increasing a detection distance of a part of the detection area.

[0009]

In the photoelectric switch according to the first aspect of the invention, since the light emitting angles of the respective light projecting elements are different, the detection distance is substantially uniform regardless of the distance from the light projector, and even one unit has a wide directional angle and is stable. A wide detection area can be obtained. Further, in the photoelectric switch according to the second aspect, the detection distance of a part of the detection area becomes long, and one detection area can provide both the near and far detection areas.

In the present invention, the means described in claim 2 is not specified as long as a part of the detection area can be used for a long distance. For example, the central portion of the detection area can be used for a long distance. In this case, among the plurality of light emitting elements arranged in a radial pattern, any of the following aspects 1 to 3 may be adopted for several light emitting elements arranged in the central portion. Aspect: A high-luminance light projecting element is used.

Aspect: A light projecting element having a narrow directional angle is used. Aspect: Increase the projection current.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wide directional angle photoelectric switch of the present invention will be described below based on embodiments. FIG. 1 shows a plan view of a floodlight of a photoelectric switch according to one embodiment, FIG. 2 shows a side view thereof, and FIG. 3 shows a front view thereof. The floodlight 1 includes, as external equipment, a detection distance changeover switch 10 for changing the distance of the detection area to, for example, 1.2 m and 2.0 m, and a position display 11 for notifying the position of the switch 10. A cord 12 connected to an internal circuit board (described later) extends to the outside. Light from the light projecting element provided inside the projector 1 is emitted from the front side of the translucent main body case 20 (see FIG. 3). Further, in this example, the power indicator light 13 is also turned on during operation, and the turning on can be visually recognized through the main body case 20. The floodlight 1 is fixed to a predetermined position on the rear portion of the unmanned vehicle by passing a screw or the like through a mounting hole 14 formed in the rear portion of the main body case 20.

The inside of the projector 1 is shown in FIG. 4 and its sectional view is shown in FIG. FIG. 4 is a bottom view showing a state in which a back cover 21 (see FIG. 5) that can be detachably attached to the main body case 20 with screws is removed. Inside the light projector 1, the circuit board 30 is attached to the main body case 20 by a screw (not shown) which is passed through the screw hole 31, and the circuit board 30 is provided with 11 light emitting elements as shown in the figure for the time being. In addition to the light emitting diodes (LEDs) L1 to L11, resistors and ICs (not shown) are mounted, and the power supply indicator 13, the detection distance changeover switch 10 and capacitors are mounted on the opposite surface. ing. Each LED is provided on the front edge of the circuit board 30.
A partition plate 32 for setting the arrangement direction is attached by a screw (not shown) from the opposite surface of the substrate 30.

Eleven LEDs (L1 to L1) are provided in each space formed by each partition wall 32a of the partition plate 32.
1) is located in a recumbent position, and the central LED as a whole
Five LEDs are symmetrically arranged on the left and right with respect to (L6). As a result, each LED (L1 to L1
In 1), the light emission angle is changed to be radially arranged. The lead frames of the LEDs (L1 to L11) are bent at a right angle and soldered to the wiring pattern of the series connection on the circuit board 30. The cord 12 is also connected to the circuit board 30 by soldering.

A circular hole 33 is formed near the center of the circuit board 30 and extends from the upper surface of the body case 20 to a cylindrical portion 23.
Is inserted into the circular hole 33, and the back cover 21 is fixed to the main body case 20 by utilizing the screw hole 24 formed in the cylindrical portion 23. On the other hand, a plan view of the light receiver 2 is shown in FIG. 6, and a side view thereof is shown in FIG.
FIG. 8 shows a front view. The light receiver 2 has a translucent cover 41 attached to the front part of a main body case 40, and two light receiving elements (described later) are provided in the cover 41. Further, the operation indicator lamp 43 provided inside the main body case 40 can be seen through from the upper surface of the main body case 40 so that the operation of the light receiver 2 can be confirmed, and the cord 44 extends from the rear portion. . Further, the body case 40
A ridged screw hole portion 45 is provided in the bottom portion of the to extend in the transverse direction, and the screw hole portion 45 is used to fix the light receiver 2 at a predetermined position in the front portion of the unmanned vehicle.

The inside of the light receiver 2 is shown in FIG. Cover 41
A holder 50 is disposed inside the holder 50. The holder 50 has inclined surfaces 50a and 50b facing outward from the center of the tip thereof, and light receiving elements (for example, phototransistors) 60 and 61 are provided on the inclined surfaces 50a and 50b. Installed symmetrically. By mounting the light receiving elements 60 and 61 on the inclined surfaces 50a and 50b, the light receiving range is widened corresponding to the light of the wide directional angle from the light projector 1, and the detection area of the wide directional angle is obtained.

Next, the circuit configuration of the photoelectric switch composed of the light projector 1 and the light receiver 2 will be outlined with reference to the block diagram shown in FIG. However, the basic configuration of the circuit is not much different from the conventional photoelectric switch. The power of the light projector 1 is DC 12 to 24V and is input to the power supply circuit 70. The power supply indicator 13 is connected to the power supply circuit 70. Further, an oscillation circuit 71 and a light projecting element drive circuit 72 are connected to the power supply circuit 70, and the light emission of 11 LEDs (L1 to L11), which are light projecting elements, is controlled. Further, a signal from the detection distance changeover switch 10 is inputted to the light projecting element drive circuit 72, and a detection area changeover circuit 73 which operates based on the detection area changeover signal is connected thereto.

On the other hand, the power source of the light receiver 2 is also DC 12-24V.
Then, the power supply circuit 80 is entered. The light from the projector 1 is received by the light receiving elements 60 and 61 and converted into an electric signal, which is amplified by the amplifier circuit 81 and further output circuit 82.
And is output as a detection signal to the outside of the light receiver 2. The operation indicator lamp 43 lights up while the light receiver 2 is operating. FIG. 11 shows a detection area obtained by the above photoelectric switch. Since the LEDs (L1 to L11) are radially arranged as described above, the detection distance is uniform over the range of about 150 ° from the projector 1, and the detection area A has a beautiful fan shape and is stable. Detection can be performed. For this reason, for example, when the projector 1 is attached to the rear part of the unmanned vehicle and the light receiver 2 is attached to the front part, when the vehicles in front and behind approach and curve, the light from the projector 1 of the front vehicle is received by the receiver 2 of the following vehicle. Since it can be reliably caught, it is possible to prevent a rear-end collision in a curve.

The detection area A shown in FIG. 11 is for short distance, but FIG. 12 shows another embodiment in which it is used for both near and far. The detection area of FIG. 12 is an area A for short distance,
Area B for long distance combined
As a result, the detection distance in the central part of the area becomes long, and it is possible to detect even an unmanned vehicle far away in front. In order to obtain this detection area B, it may be selected appropriately from the above modes (1) to (3). That is, for example, in the projector shown in FIG. 4, for the three LEDs (L5 to L7) in the central portion, a high-brightness LED is used in the case of the mode, and an LED with a narrow directional angle is used in the mode. Then, it suffices to take measures to increase the projection current. By doing this, the three LEDs in the center
The light of (L5 to L7) becomes brighter, and only the front of these LEDs is illuminated more brightly, and the detection distance in this region becomes longer.

It is needless to say that the above embodiment is an example of a book and various modifications can be made. For example, although 11 LEDs are used in the projector, more or less than 11 LEDs may be used, and the manner of arrangement may be appropriately changed. Further, in the case of bifocal use, by adopting the mode (increasing the light emitting current) and providing an appropriate changeover switch, the detection area can be used only for the short distance as shown in FIG. 11 and for the bifocal use of FIG. Can be switched.

Further, although two light receiving elements are used in the light receiving device, the number may be larger. For example, a plurality of light receiving elements may be arranged radially like the LED of the projector.

[0022]

As described above, the photoelectric switch according to the first aspect of the invention has the following effects because the plurality of light emitting elements are radially arranged by changing the light emitting angle. (1) The light directivity angle is wide, and the detection distance is uniform from the projector, so that a wide-angle and stable detection area can be obtained. Therefore, for example, when mounted on an unmanned vehicle, a single photoelectric switch can sufficiently prevent a rear-end collision in a curve. (2) Since only one photoelectric switch is required, the mounting space for the photoelectric switch may be small, and the cost is reduced due to the reduction of wiring man-hours, the need for a main circuit, etc.

Since the photoelectric switch according to the second aspect further has a means for increasing the detection distance of a part of the detection area, it has the following effects. (3) Since both the near and far detection areas can be obtained with one photoelectric switch, the mounting space for the photoelectric switch is small and the cost is low when it is installed in an unmanned vehicle or the like.

[Brief description of drawings]

FIG. 1 is a plan view of a floodlight of a photoelectric switch according to an embodiment of the present invention.

FIG. 2 is a side view of the floodlight shown in FIG.

3 is a front view of the floodlight shown in FIG. 1. FIG.

FIG. 4 is a bottom view of the floodlight shown in FIG. 1 with a back cover removed.

5 is a cross-sectional view of the floodlight shown in FIG.

FIG. 6 is a plan view of a light receiver of a photoelectric switch.

FIG. 7 is a side view of the light receiver shown in FIG.

FIG. 8 is a front view of the light receiver shown in FIG.

9 is a cross-sectional view of the light receiver shown in FIG.

FIG. 10 is a block diagram showing a circuit configuration of a photoelectric switch including a light projector and a light receiver.

FIG. 11 is a diagram showing a short-distance detection area obtained when the photoelectric switch of the present invention is used.

FIG. 12 is a diagram showing a bifocal detection area obtained when the photoelectric switch of the present invention is used.

FIG. 13 is a diagram showing a short-distance detection area obtained when a photoelectric switch according to a conventional example is used.

FIG. 14 is a diagram showing a bifocal detection area obtained when a photoelectric switch according to a conventional example is used.

[Explanation of symbols]

 1 Light projector 2 Light receiver L1-L11 Light emitting diode (light emitting element) 60, 61 Light receiving element

Claims (2)

[Claims] 1. A photoelectric switch comprising a light-emitter that emits light and a light-receiver that receives light from the light-emitter, wherein the light-emitter has a plurality of light-emitter elements radially arranged with different light emission angles. A wide directional angle photoelectric switch. 2. The wide directional angle photoelectric switch according to claim 1, wherein the projector has means for increasing a detection distance of a part of the detection area.