JPH0442787Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is designed so that when an object to be detected exists within the range of light emitted by the light projector, the light reflected from the object is detected by the light receiver. The present invention relates to a reflective photoelectric switch suitable for use in applications where a wide detection area is required, such as when detecting obstacles on the travel course of an automatic guided vehicle.

[Prior Art] When a reflective photoelectric switch is installed in the front part of an automatic guided vehicle and the reflective photoelectric switch is used to detect obstacles on the course on which the automatic guided vehicle is traveling, the reflective photoelectric switch is used. It is necessary to enlarge the detection area in the lateral direction (horizontal direction), and it is desirable to configure the detection area so that it can also be expanded in the distance direction depending on the traveling speed of the automatic guided vehicle. However, in the past, there was no reflective photoelectric switch that actively enlarged the detection area in the lateral direction, and in conventional reflective photoelectric switches, the detection area could only be adjusted by, for example, adjusting the sensitivity on the light receiving side. Because of this configuration, there is a problem that the adjustment when expanding the detection area in the far and near direction becomes inaccurate, which may result in a blind spot in the detection area, which is an unresolved issue. Ta.

[Purpose of the invention] The purpose of the invention is to widen the detection area for obstacles located in front of the automatic guided vehicle in the lateral direction, and to make adjustment when expanding the detection area in the distance direction extremely easy and reliable. It is an object of the present invention to provide a photoelectric switch for detecting obstacles in an automatic guided vehicle, which has the following effects.

[Summary of the invention] In order to achieve the above object, the present invention provides a main light projector for near area detection and an auxiliary light projector for far area detection, each of which has a plurality of light projecting elements arranged in a row in the horizontal direction. At the same time, a light-receiving section consisting of a plurality of light-receiving elements arranged in a row in the horizontal direction is also provided so that the light-receiving range spreads in the horizontal direction. The main light emitter, auxiliary light emitter, and light receiver are arranged vertically, and the light emitting range of the main light emitter and the auxiliary light emitter is the same as the light receiving range of the light receiver. The light emitting elements in the main light emitting part and the light emitting elements in the auxiliary light emitting part are set in overlapping near and far regions at different positions, respectively, and light up at different timings,
The light receiving section is characterized in that it is configured to select the light reception state in synchronization with each of the lighting timings and provide the selection results to an automatic guided vehicle that performs speed control according to the selection results.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

In Figures 1 to 4, 1 is the main body case of a reflective photoelectric switch with a built-in amplifier, and the front side of the case has two through holes 1a and 1b located above and below.
are formed, and lenses 2 and 3 are installed in the through holes 1a and 1b. Reference numeral 4 denotes a light receiving section located within the main body case 1 on the back side of the lower lens 3, and is composed of, for example, three photodiodes 5a, 5b, and 5c, which are light receiving elements, arranged in a row in the horizontal direction. At this time, each photodiode 5a, 5
b and 5c are configured such that their optical axes are directed in the horizontal direction and intersect with each other, and as a result, the light receiving range A of the light receiving section 4 takes on a fan shape that spreads in the horizontal direction. Reference numeral 6 denotes a main light emitting section provided inside the main body case 1 on the back side of the upper lens 2, which includes, for example, three light emitting diodes 7 as light emitting elements.
A, 7b, and 7c are arranged in rows in the horizontal direction. At this time, the light emitting diodes 7a, 7b, 7c are configured such that their optical axes are directed diagonally downward and intersect with each other, and as a result, the light emitting range B of the main light projecting section 6 is
has a fan shape that spreads laterally, and the main body case 1
It is set in a near region that overlaps with the light receiving range A of the light receiving section 5 in front of the light receiving section 5 . 8 is also the main case 1
An auxiliary light projecting section is located on the back surface of the upper lens 2 and below the main light projecting section 6, and includes, for example, three light projecting elements such as light emitting diodes 9a, 9b, 9c. are arranged in horizontal rows.
At this time, each light emitting diode 9a, 9b, 9c
are constructed such that their optical axes are directed diagonally downward at a gentler angle than the optical axis of the main light projecting section 6 and intersect with each other.As a result, the light emitted from the auxiliary light projecting section 8 The range C has a fan shape that spreads in the horizontal direction, and is set in a far area that is farther away than the light projection range B by the main light projector 6 and overlaps with the light receiving range A of the light receiver 5.

In FIG. 5 showing the electrical configuration, 10 is a pulse oscillation circuit that generates a pulse signal Ps of a constant period;
11 is a flip-flop that receives the pulse signal Ps as a trigger signal;
Each time Q rises, a high level signal is alternately output from either output terminal Q. 12 is an AND circuit which receives the pulse signal Ps at one input terminal and receives the output from the output terminal Q of the flip-flop 11 at the other input terminal; through the driver 13. 14 is an AND circuit which receives the pulse signal Ps at one input terminal and receives the output from the output terminal of the flip-flop 11 at the other input terminal, and sends the output to the light emitting diodes 9a, 9b, 9c in the auxiliary light emitter 8. It is given via the driver 15. At this time, driver 1
3 and 15 are high level signals (pulse signal Ps)
The light emitting diode 7a~ which only responds when received
7c or 9a to 9c are configured to be lit. Further, 16 is a photodiode 5a, 5
A photoelectric conversion circuit 17 converts the light reception signals b and 5c into a voltage signal, and 17 is an adjustable gain amplifier that amplifies the voltage signal. 18 converts the voltage signal from the amplifier 17 into a first signal processing circuit 19 and a second signal processing circuit.
This is a switching element for selectively applying a signal to either one of the first signal processing circuits 20, and when the output from the output terminal of the flip-flop 11 is a low level signal, the signal is applied to the first signal processing circuit 19.
The configuration is such that when the output is a high level signal, the signal is switched to the second signal processing circuit 20 side. Incidentally, each of the signal processing circuits 19 and 20 is as follows:
It is configured to detect and integrate an input voltage signal in synchronization with the pulse signal Ps, and then output it as a detection signal Sd. Reference numerals 21 and 22 denote first and second comparison circuits, which compare the peak values of the detection signals Sd from the corresponding signal processing circuits 19 and 20 with a predetermined reference voltage Vs, and determine whether the relationship Sd>Vs is established. Sometimes a switching signal is output. here,
The photoelectric switch is mounted on an automatic guided vehicle (not shown), and is connected to first and second comparison circuits 21 and 22.
A switching signal from the automatic guided vehicle is given to the control device of the automatic guided vehicle. In this case, the control device of the automatic guided vehicle decelerates the automatic guided vehicle when the switching signal is output from the comparison circuit 22 while the automatic guided vehicle is running, and decelerates the automatic guided vehicle when the switching signal is output from the comparison circuit 21. The transport vehicle is now stopped.

According to the above configuration, each time the pulse signal Ps is output from the pulse oscillation circuit 10, the output of the flip-flop 11 is inverted, and the AND circuit 1
2 and 14 alternately permit the passage of the pulse signal Ps. Therefore, the drivers 13 and 15 alternately light up the groups of light emitting diodes 7a to 7c and the groups of light emitting diodes 9a to 9c as shown in FIG. As a result of driving the main light projecting section 6 and the auxiliary light projecting section 8 in this way, a near area where the light projecting range B by the main light projecting section 6 and the light receiving range A by the light receiving section 4 overlap and the auxiliary light projecting section 8 are created. When a detected object exists in any of the far regions where the light projection range C and the light receiving range A of the light receiving section 4 overlap, the reflected light from the detected object is received by the light receiving section 4. Become. In this case, when the light receiving section 4 receives the reflected light from the nearby area (at this time, a low level signal is output from the output terminal of the flip-flop 11), the switching element 18 switches the output terminal from the flip-flop 11. Since the signal is switched to the first signal processing circuit 19 side in response to the low level signal of A switching signal is output from 21. Further, when the light receiving section 4 receives reflected light from a far region (at this time, a high level signal is output from the output terminal of the flip-flop 11), the switching element 18 switches the signal from the output terminal of the flip-flop 11. Since it is switched to the second signal processing circuit 20 side in response to the high level signal, when the level of the detection signal Sd from the second signal processing circuit 20 exceeds the reference voltage Vs, the second comparison circuit 22 A switching signal is output from. That is, when a detected object exists in a near region, a switching signal is output from the first comparison circuit 21, and when a detected object exists in a far region, a switching signal is output from the second comparison circuit 22. . As a result, the automatic guided vehicle decelerates when the switching signal is output from the second comparison circuit 22 while traveling, and stops when the switching signal is output from the first comparison circuit 21.
It can be stopped without any impact. At this time, a light receiving range A by the light receiving section 4, a light projecting range B by the main light projecting part 6, the auxiliary light projecting part 8,
Since C has a fan shape that spreads laterally, the near region and the far region can be made wider laterally. Moreover, since the near area and far area are configured to be enabled alternately at relatively early timing depending on the cycle of the pulse signal Ps, the detection area for obstacles located in front of the automatic guided vehicle can be adjusted in the far and near directions. Adjustments when enlarging can also be made extremely easily and reliably.

In the above embodiment, the light receiving section 4, the main light emitting section 6, and the auxiliary light emitting section 8 are each composed of three photodiodes 5a to 5c and three light emitting diodes 7a to 7c, 9a.
9c, but it goes without saying that a larger number of photodiodes and light emitting diodes may be provided.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, devices other than light emitting diodes and photodiodes may be used as the light emitting element and light receiving element without departing from the gist thereof. It can be implemented with various modifications within the range.

[Effect of the invention] According to the present invention, as is clear from the above explanation, when an object to be detected is present in the light projection range of the light projector, the light reflected by the object to be detected is reflected by the light receiver. In the photoelectric switch for detecting obstacles in an automatic guided vehicle, the detection area for obstacles located in front of the automatic guided vehicle can be widened in the lateral direction, and the detection area can be adjusted in the far and near directions extremely easily. This has the practical effect of making it possible to perform the process reliably.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 and 2 are front and side views showing the arrangement of the light projecting section and the light receiving section, respectively, and FIG. 3 is an explanation of the light receiving range of the light receiving section. Figure 4 is a perspective view of the entire structure;
FIG. 5 is an electrical configuration diagram, and FIG. 6 is a diagram showing the lighting timing of the light emitting diodes. In the figure, 1 is the main body case, 2 and 3 are lenses, 4 is a light receiving section, 5a, 5b, and 5c are photodiodes (light receiving elements), 6 is a main light emitter, and 7a, 7b, and 7c are light emitting diodes (light emitting elements). ), 8 is an auxiliary light emitter, 9
a, 9b, and 9c indicate light emitting diodes (light projecting elements).

Claims (1)

[Scope of utility model registration request] In an obstacle detection photoelectric switch for an automatic guided vehicle that is installed on an automatic guided vehicle and detects an obstacle located in front of the automatic guided vehicle, a plurality of light emitting elements are arranged in a row in the horizontal direction so as to have a fan-shaped light emitting range. a main light emitting section for detecting a near area, and an auxiliary light emitting section for detecting a far area, comprising a plurality of light emitting elements arranged in a horizontal direction so as to have a fan-shaped light emitting range; A main light emitting part,
The auxiliary light emitter and the light receiver are arranged above and below, and the light emitting ranges of the main light emitter and the auxiliary light emitter are set to a near region and a far region that overlap the light receiving range of the light receiver at different positions, and The light emitting element in the main light emitting part and the light emitting element in the auxiliary light emitting part are lit at different timings, and the light receiving part selects the light reception state in synchronization with each of the above lighting timings, and transmits the selection results to the relevant one. 1. A photoelectric switch for detecting obstacles in an automatic guided vehicle, characterized in that the photoelectric switch is configured to apply speed control to an automatic guided vehicle according to a selection result.