JP2528674Y2 - Photoelectric detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric detection device in which a plurality of photoelectric switches for judging the presence or absence of an object by projecting light and detecting the presence or absence of reflected light are sequentially arranged.

[0002]

2. Description of the Related Art A photoelectric switch is known as a means for detecting the presence or absence of an object moving on a conveyor line or the like. This is to determine the presence or absence of an object by projecting light onto the path of the object and detecting the presence or absence of reflected light from the moving object. In such a photoelectric switch,
In order to reduce power consumption and prevent mutual interference, the projection light is pulsed and intermittently projected.

FIG. 7 is an exploded perspective view showing an example of a conventional photoelectric switch of this type. This photoelectric switch is a so-called optical fiber type and mainly comprises a main body 1 and a detecting section 2. ing. The main body 1 includes a case 3, a circuit board 5 built in the case 3 and connected to a wiring 4 such as a power cable and an output cable, a light emitting element 6 and a light receiving element 7 provided on the circuit board 5, An upper plate 10 that covers the upper part of the case 3 and to which the indicator lamp 8 and the adjustment knob 9 are attached, and is mounted on the side surface of the case 3,
It comprises a light receiving element 7 and a connecting portion 13 having insertion holes 11 and 12 facing each other. On the other hand, the detection unit 2
A detection head 15 disposed opposite to the optical head 4, and a pair of lights having one end connected to the detection head 15 and the other end connected to the light emitting element 6 and the light receiving element 7 through the insertion holes 11 and 12. It consists of a fiber 16. In such a conventional photoelectric switch, when sensing light is intermittently output from the light projecting element 6 in response to a timing signal of a predetermined cycle, the sensing light is guided through the optical fiber 16 and the detection head 1
5, the light is projected on the object 14 to be detected. At this time, the detected object 1
When the light reflected by the light 4 enters the detection head 15, the reflected light is guided through the optical fiber 16 and received by the light receiving element 7, and the detection signal is transmitted from the circuit board 5 through the wiring 4 in accordance with the light reception. Output. On the other hand, when there is no object 14, no detection signal is output from the circuit board 5 because the reflected light is not received by the light receiving element 7.

FIG. 8 is an exploded perspective view showing another example of a conventional photoelectric switch. This photoelectric switch is a so-called lens type and is different from the optical fiber type shown in FIG. The detector mainly differs in that the pulse light output from the light projecting element 17 is projected onto the object 14 via the light projecting lens 18, and the light reflected by the object 14 is reflected by the light receiving lens 19. The light is received by the light receiving element 20 via the light receiving element.

Usually, not only one photoelectric switch but a plurality of photoelectric switches are used for detecting the presence or absence of an object. For example, on a conveyor line, a plurality of photoelectric switches are installed at one location, such as a photoelectric switch that projects light from a lateral direction, a photoelectric switch that projects light from below, and a photoelectric switch that projects light from above, so that object detection can be performed more accurately. (Hereinafter, this projection light is referred to as sensing light). However, when a plurality of photoelectric switches are arranged in close proximity or close proximity in one place, and each of the photoelectric switches continuously emits light, each of the photoelectric switches may also receive sensing light projected by a photoelectric switch other than its own. There is. This is referred to as the above-mentioned mutual interference. In the photoelectric switch, the light is emitted intermittently so that the light emission timing does not overlap with the other photoelectric switch, and the reflected light by its own light and the light emitted by the other photoelectric switch are used. Means for distinguishing the received light (interference light) is provided.

FIG. 9 is a block diagram showing a conventional photoelectric switch, wherein 21 is a periodic pulse generating circuit, 22 is a light projecting unit, 23 is a light receiving unit, 24 is a gate circuit, 25 is an integrating circuit, and 26 is a judgment. Circuit. For example, a pulse generating circuit 21, a gate circuit 24, an integrating circuit 25, and a judging circuit 26 are provided on the circuit board 5, the light projecting unit 22 includes the light projecting element 6, and the light receiving unit 23 includes the light receiving element 7 And so on.

In FIG. 9, a periodic pulse generating circuit 21
Always generates a pulse P1 having a constant period.
2 is driven by this pulse P1, and projects sensing light in a pulse shape at the same cycle and duty ratio as this pulse P1. When the sensing light is reflected by an object (not shown), the reflected light is received by the light receiving unit 23, and a pulse P2 is output. If the pulse P2 is obtained by the reflected light accompanying the light projection of its own light projecting unit 22, the pulse P2
Although the timing coincides with 1, the timing does not coincide with the pulse P1 if it is obtained by receiving the sensing light from another photoelectric switch. Therefore, the light receiving unit 23
The output pulse P2 is supplied to the gate circuit 24 using the pulse P1 as a gate pulse, and only the pulse due to its own light projection is extracted from the pulse P2. The output pulse of the gate circuit 24 is captured by the integration circuit 25 at the timing of the pulse P1, and when the integrated value is equal to or greater than a preset threshold, the determination circuit 26 determines that there is an object.

The sensing light projected from the light projecting unit 22 onto the object is reflected by the object, but the reflected light from the object is scattered, and a part of the reflected light is received by the light receiving unit 23. For this reason, the light receiving amount of the light receiving unit 23 is small. Therefore, the pulse P2 is generated from a small amount of light. However, if the presence or absence of an object is determined for each pulse P2, the detection accuracy of the presence or absence is low. For this purpose, an integration circuit 25 is provided, which integrates the pulses extracted by the gate circuit 24, and makes a determination according to the magnitude of the integrated value. Although the integration circuit 25 may be an analog integration circuit, a pulse counter is normally used, and the determination circuit 26 has an object based on the count value when, for example, eight pulses of the pulse P1 are continuously supplied from the gate circuit 24. Is determined.

In such a photoelectric switch, if the duty ratio of the output pulse P1 of the periodic pulse generating circuit 21 is made sufficiently smaller than the period, the probability of mutual interference is reduced and the power consumption is reduced. However, each photoelectric switch is completely independent, and the light projection periods of each photoelectric switch are almost equal. For this reason, the light emission timing may overlap with two or more photoelectric switches. In such a case, in FIG. 9, a pulse P2 whose timing coincides with the pulse P1 is output from the light receiving unit 23 because another photoelectric switch emits light even though there is no object. Such a pulse P2
Cannot be removed by the gate circuit 24, so that an error occurs in the determination of the presence or absence of an object.

An example of a technique for preventing such mutual interference is disclosed in Japanese Patent Publication No. Sho 60-51043. This is because, as shown in FIG. 10, the interference discriminating circuit 27 discriminates whether or not the output pulse of the gate circuit 24 is due to the interference light. 21a is controlled, and the phase of the pulse P1 to be generated is advanced or delayed.

In Japanese Patent Application Laid-Open No. 61-138192, a pulse signal obtained by receiving an interference light is extracted, a pulse having the same frequency as this pulse signal and having a different phase is generated, and the light projecting section is driven. There is disclosed a technology in which light is emitted at the same frequency and with a different phase from light.

Further, in Japanese Patent Application Laid-Open No. 63-263917, when a pulse coincident with the light emission timing is obtained from the light receiving section, the light emission cycle is sequentially shifted from the reference cycle, and when a predetermined number of such pulses are obtained. There is disclosed a technique in which a light projection cycle is returned to an original reference cycle. According to this, when the light emission timing of another photoelectric switch having a light emission cycle substantially equal to the self coincidence with the light emission timing of itself, a pulse corresponding to the light emission timing is obtained from the light receiving unit, so that the light emission of the self light emission part is obtained. The light cycle changes sequentially. On the other hand, the light emission periods of the other photoelectric switches do not change. Therefore, its own light emission timing is shifted from the light emission timing of the other photoelectric switch, and the pulse from the light receiving unit due to the light from the other photoelectric switch is removed by the gate circuit. However, the light receiving unit receives the light emitted by the light receiving unit itself, and the output pulse of the light receiving unit coincides with the light emitting timing of the light receiving unit. When the predetermined number of such pulses are obtained, the light emitting cycle of the self returns to the original reference cycle. However, at this time, the light emission timing of
Due to the above operation, the light emission timing is shifted from the previous light emission timing, and is therefore shifted from the light emission timing of another photoelectric switch.

[0013]

The above prior arts all attempt to prevent mutual interference with other photoelectric switches by shifting the light emission timing. If the number is small,
It is quite effective. However, when a large number of photoelectric switches are provided in one place, the light emission timings of these photoelectric switches must be sequentially different in order to eliminate mutual interference. Is insignificant. Therefore, if the light emission timings of two photoelectric switches coincide with each other and the light emission timings of the two photoelectric switches are shifted, the light emission timings of the other photoelectric switches become coincident with each other, and mutual interference is completely prevented. Can not do.

If the photoelectric switch is provided with the mutual interference preventing means as described above, the light emission timing is shifted in any of the plurality of photoelectric switches in which mutual interference has occurred. In this case, in order to eliminate mutual interference due to these shifts, it is necessary to set a shift amount and a shift direction of the light emitting timing unique to each photoelectric switch, and it is very difficult to determine them. Becomes

Further, in the above-mentioned prior art, a mutual interference preventing means having a complicated circuit configuration is required.

An object of the present invention is to provide a photoelectric detecting device capable of sequentially operating a plurality of photoelectric switches provided in one place.

[0017]

In order to achieve the above object, a light emitting element for intermittently projecting a sensing light in response to a timing signal of a predetermined period, and a light receiving element for receiving a light reflected by an object to be detected. A plurality of photoelectric switches that determine the presence or absence of an object based on the presence or absence of a light pulse having the same timing as the sensing light. In the photoelectric detection device arranged in close proximity, the photoelectric switch includes a receiving unit that is disposed on one side of the photoelectric switch and receives a pulse-like magnetic signal. Signal generation means for generating a synchronization timing signal synchronized with a signal or a delay timing signal delayed by a predetermined time from the magnetic signal and outputting the signal to the light projecting element; Disposed on the other side of the switch,
Exciting means for outputting a pulsed magnetic signal to the outside in synchronization with the synchronization timing signal or the delay timing signal; and at least one of the receiving means and the exciting means, an auxiliary core provided on the side wall. ,
The receiving means, the exciting means, and the auxiliary core are arranged on the same axis parallel to the arrangement direction of the photoelectric switches, and from the exciting means of the preceding photoelectric switch to the receiving means of the next photoelectric switch via the auxiliary core. It is configured to transmit a magnetic signal.

[0018]

As described above, according to the present invention, the receiving means and the exciting means are respectively disposed on one side and the other side of each photoelectric switch, and for example, both of the receiving means and the exciting means are provided on the side wall of the case. Since the receiving means, the exciting means and the auxiliary core are arranged on the same axis parallel to the arrangement direction of the photoelectric switches, a plurality of the photoelectric switches are provided. When a pulse-like magnetic signal is output from the excitation means of the photoelectric switch of the preceding stage, the photoelectric switch of the next stage receives the magnetic signal by the receiving unit, and based on the magnetic signal, the synchronous timing signal or the delay by the signal generating unit. A timing signal is generated and output to the light emitting element. Therefore, the light projecting element intermittently projects sensing light according to the synchronization timing signal or the delay timing signal, receives reflected light reflected by the object to be detected by the light receiving element, and adjusts the timing between the sensing light and the timing. The presence or absence of an object is determined based on the presence or absence of reception of the coincident light pulse. Thereby, a plurality of photoelectric switches provided in one place can be sequentially operated.
In addition, since the auxiliary cores provided on the side walls of the two cases adjacent to each other are very close to each other and accurately oppose each other, the magnetic signal output from one of the exciting means can be efficiently received by the other receiving means. .

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a photoelectric detector according to the present invention;

FIG. 1 is an exploded perspective view of a photoelectric switch provided in a first embodiment of the photoelectric detection device of the present invention, and FIG.
FIG. 3 is a perspective view showing an arrangement state of the photoelectric detection device of FIG.

In the photoelectric detecting device of this embodiment shown in FIG.
The photoelectric switch 31 and the next-stage photoelectric switch 32 screwed to the photoelectric switch 31 are closely arranged. As shown in FIG. 1, the photoelectric switch 31 is formed in a rectangular parallelepiped shape and has a case 33 having an opening, and a pair of optical fibers respectively connected to a light emitting element and a light receiving element (not shown) built in the case 33. 34, 35, an upper plate 36 mounted on the upper end of the case 33,
A circuit board 37 having a signal generating means (not shown) for generating a synchronous timing signal or a delayed timing signal and outputting the generated signal to the light emitting element;
1. The receiving means 38 shown in FIG. 2 provided on one side of the photoelectric switch 31 for receiving a pulse-like magnetic signal, and provided on the other side of the photoelectric switch 31 for receiving the synchronous timing signal or the delayed timing signal. Exciting means 39 for outputting a pulsed magnetic signal to the outside in synchronization.

The receiving means 38 is attached to one side surface of the circuit board 37, and is provided with a magnetic core 41 located inside one side wall 33 a of the case 33, and a receiving coil 42 wound around the core 41. And an auxiliary core 43 molded integrally with the case 33 and having an end surface substantially the same as the outer surface of the one side wall 33a. Similarly, the exciting means 39 is attached to the other side surface of the circuit board 37, and includes a magnetic core 44 located inside the other side wall 33b of the case 33, and a transmission coil 45 wound around the core 44. And an auxiliary core 46 molded integrally with the case 33 and having an end surface substantially the same as the outer surface of the other side wall 33b. As shown in FIG. 1, the auxiliary core 46 includes a cylindrical core 47 and a ring-shaped core 48 located around the cylindrical core 47, and the other auxiliary cores 43 have the same configuration. The receiving means 38, the exciting means 39, and the auxiliary cores 43 and 46 are arranged on the same axis L1 parallel to the arrangement direction of the photoelectric switches 31 and 32.

Similarly, the next-stage photoelectric switch 32 has an auxiliary core 49 disposed on the axis L1 as shown in FIG. These photoelectric switches 31, 32 are
They are connected via screws 50 in a state where they are arranged closely.

In the first embodiment, when a pulse-like magnetic signal is transmitted to the photoelectric switch 31, the photoelectric switch 31 receives the magnetic signal by the receiving means 38,
A synchronous timing signal synchronized with the magnetic signal by the pulse generating circuit or a delayed timing signal delayed by a predetermined time from the magnetic signal is output, and the sensing light is intermittently output from the optical fiber according to the synchronous timing signal or the delayed timing signal. The light is projected via the detection head 34 and the detection head. At this time, the light reflected by the object is received via the detection head and the optical fiber 35, and the presence or absence of the object is determined based on the presence or absence of the light pulse having the same timing as the sensing light. When the magnetic signal is output in synchronization with the synchronization timing signal or the delay timing signal by the excitation means 39, the photoelectric switch 32 of the next stage receives the magnetic signal by the receiving means and determines the presence or absence of an object according to the magnetic signal. It has become.

In the first embodiment configured as described above, 1
A plurality of photoelectric switches 31 and 32 provided in parallel at a location can be sequentially operated. Also, the excitation means 39 of the photoelectric switch 31 has an auxiliary core 46 buried in the side wall 33b of the case 33, and similarly, the receiving means of the next-stage photoelectric switch 32 has an auxiliary core buried in the side wall of the case. The excitation means 3 of these photoelectric switches 31
9 and the receiving means of the next-stage photoelectric switch 32 are arranged on the same axis L1 parallel to the arrangement direction of the photoelectric switches 31 and 32, so that the auxiliary core 46 of the exciting means 39 and the auxiliary core of the receiving means Are very close and exactly opposite. For this reason, the transmission coil 45 of the photoelectric switch 31
The magnetic coupling between the coil and the receiving coil of the photoelectric switch 32 becomes very dense, and most of the magnetic flux generated in the transmitting coil 45 passes through the receiving coil.
The magnetic signal generated in the transmission coil 45 by the synchronization timing signal or the delay timing signal is efficiently captured by the reception coil of the photoelectric switch 32, and high transmission efficiency of the synchronization timing signal or the delay timing signal is obtained.

In this embodiment, the optical fiber 3
Although the case where the optical fiber type photoelectric switch having 4 and 35 is provided in parallel is exemplified, the present invention is not limited to this, and when a plurality of lens type photoelectric switches are provided in the same manner, the photoelectric switches are sequentially operated in the same manner. Can be done. further,
In the present embodiment, the case of the photoelectric detection device including two photoelectric switches 31 and 32 is illustrated, but the present invention is not limited to this, and the photoelectric detection device including three or more photoelectric switches is one.
These photoelectric switches can be operated sequentially even if they are provided in a location. Further, in this embodiment, both the receiving means 38 and the exciting means 39 are provided with the auxiliary cores 43 and 46, respectively. However, if necessary, only one of the auxiliary cores may be provided with the auxiliary core.

FIG. 4 is an exploded perspective view of a photoelectric switch provided in a second embodiment of the photoelectric detection device of the present invention, and FIG.
FIG. 6 is a perspective view showing an arrangement state of the photoelectric detection device of FIG. 4 to 6, the same components as those shown in FIGS. 1 to 3 described above are denoted by the same reference numerals. That is, 34 and 35 are optical fibers, 36 is a top plate, 37 is a circuit board, and 50 is a screw.

In the photoelectric detecting device of this embodiment shown in FIG.
Similarly to the above-described first embodiment, the photoelectric switch 51 includes:
The next-stage photoelectric switch 52 screwed to the photoelectric switch 51 is closely arranged. The photoelectric switch 51 is formed in a rectangular parallelepiped shape and has a case 5 having an opening.
3, a receiving means 54 shown in FIG. 5 disposed on one side of the photoelectric switch 51 for receiving a pulse-like magnetic signal, and a receiving means 54 disposed on the other side of the photoelectric switch 51 for receiving a pulse-like magnetic signal. And an exciting unit 55 for outputting a magnetic signal to the outside.

The receiving means 54 is attached to one side surface of the circuit board 37, and is provided with a magnetic core 61 positioned inside one side wall 53a of the case 53, and a receiving coil 62 wound around the core 61. And an auxiliary core 63 provided on the one side wall 53a. The exciting means 55 is attached to the other side surface of the circuit board 37, and includes a magnetic core 64 located inside the other side wall 53 b of the case 53, and a transmitting coil 65 wound around the core 64.
And an auxiliary core 66 provided on the other side wall 53b. As shown in FIG. 4, the auxiliary core 66 is press-fitted into a hole 67 passing through the side wall 53b.
3b has substantially the same end face as the outer face, and the other auxiliary cores 63 are also the same. The receiving means 54, the exciting means 55, and the auxiliary cores 63 and 66 are arranged on the same axis L2 parallel to the arrangement direction of the photoelectric switches 51 and 52.

Similarly, the photoelectric switch 52 at the next stage has an auxiliary core 68 provided on the axis L2 as shown in FIG. These photoelectric switches 51 and 52 are
They are connected via screws 50 in a state where they are arranged closely.

Also in the second embodiment, when a pulse-like magnetic signal is transmitted to the photoelectric switch 51, the photoelectric switch 51 receives the magnetic signal by the receiving means 54, and
A pulse generation circuit outputs a synchronization timing signal synchronized with the magnetic signal or a delay timing signal delayed by a predetermined time from the magnetic signal, and intermittently outputs the sensing light according to the synchronization timing signal or the delay timing signal to the optical fiber. The light is projected through the detection head 34 and the detection head. At this time, the light reflected by the object is received via the detection head and the optical fiber 35, and the presence or absence of the object is determined based on the presence or absence of the light pulse having the same timing as the sensing light. When a magnetic signal is output in synchronization with the synchronization timing signal or the delay timing signal by the excitation means 55, the next-stage photoelectric switch 5
Reference numeral 2 is received by the receiving means, and the presence or absence of an object is determined according to the magnetic signal.

In the second embodiment having the above-described structure, the same effects as those of the first embodiment can be obtained.
In the present embodiment, the case where the optical fiber type photoelectric switch having the optical fibers 34 and 35 is also provided is illustrated. However, the present invention is not limited to this, and the case where a plurality of lens type photoelectric switches are provided side by side. Similarly, the photoelectric switches can be sequentially operated. Furthermore, the case of the photoelectric detection device including the two photoelectric switches 51 and 52 has been illustrated, but the present invention is not limited to this. Even when the photoelectric detection device including three or more photoelectric switches is provided in one place,
These photoelectric switches can be operated sequentially.
Further, in this embodiment, the receiving means 54 and the exciting means 55
Are provided with auxiliary cores 63 and 66, respectively, but if necessary, only one of them may be provided with an auxiliary core.

[0033]

[Effect of the Invention] The present invention is configured as described above.
A plurality of photoelectric switches provided side by side can be sequentially operated by transmitting a pulse-like magnetic signal. Therefore, the light emission timing between the photoelectric switches can be reduced without the need for a means for preventing mutual interference having a complicated circuit configuration. Can be reliably prevented from interfering with each other. Also, as described above,
Since the auxiliary cores provided on the side walls of the two cases adjacent to each other are very close to each other and accurately oppose each other, a high transmission efficiency is obtained by the pulsed magnetic signal. be able to.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a photoelectric switch provided in a first embodiment of the photoelectric detection device of the present invention.

FIG. 2 is a cross-sectional view of the photoelectric switch of FIG.

FIG. 3 is a perspective view showing an arrangement state of the photoelectric detection device of FIG. 1;

FIG. 4 is an exploded perspective view of a photoelectric switch provided in a second embodiment of the photoelectric detection device of the present invention.

5 is a cross-sectional view of the photoelectric switch of FIG.

FIG. 6 is a perspective view showing an arrangement state of the photoelectric detection device of FIG. 4;

FIG. 7 is an exploded perspective view showing a conventional example of an optical fiber type photoelectric switch.

FIG. 8 is an exploded perspective view showing a conventional example of a lens-type photoelectric switch.

FIG. 9 is a block diagram illustrating an operation of a conventional photoelectric switch.

FIG. 10 is a block diagram illustrating an operation of another conventional photoelectric switch.

[Explanation of symbols]

 31, 32 photoelectric switch 33 case 33a, 33b side wall 37 circuit board 38 receiving means 39 exciting means 41 core 42 receiving coil 43 auxiliary core 44 core 45 transmitting coil 46, 49 auxiliary core 51, 52 photoelectric switch 53 case 53a, 53b Side wall 54 Receiving means 55 Exciting means 61 Core 62 Receiving coil 63 Auxiliary core 64 Core 65 Transmitting coil 66, 68 Auxiliary core L1 axis L2 axis

Claims (1)

(57) [Scope of request for utility model registration] 1. A light-emitting element for intermittently projecting sensing light in response to a timing signal of a predetermined cycle, a light-receiving element for receiving light reflected by an object to be detected, and a light-emitting element and a light-receiving element. A photoelectric detection device comprising a plurality of photoelectric switches that determine the presence / absence of an object by the presence / absence of reception of a light pulse whose timing coincides with the sensing light, and a plurality of photoelectric switches are arranged close to or close to each other. The photoelectric switch includes a receiving unit that is disposed on one side of the photoelectric switch and receives a pulse-like magnetic signal, and a synchronization timing signal that synchronizes with the magnetic signal based on the magnetic signal or a signal that is more than the magnetic signal. A signal generating means for generating a delay timing signal delayed by a predetermined time and outputting the delayed timing signal to the light projecting element; and a synchronizing timer disposed on the other side of the photoelectric switch. Exciting means for outputting a pulse-like magnetic signal to the outside in synchronization with the imaging signal or the delay timing signal; and at least one of the receiving means and the exciting means, an auxiliary core provided on the side wall; The receiving means, the exciting means, and the auxiliary core are arranged on the same axis parallel to the arrangement direction of the photoelectric switches, and the magnetic force is transmitted from the exciting means of the preceding photoelectric switch to the receiving means of the next photoelectric switch via the auxiliary core. A photoelectric detection device characterized by transmitting a signal.