JPH04121131U - Photoelectric detection device - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a photoelectric detection device that sequentially operates a plurality of photoelectric switches. [Structure] The photoelectric switch 31 includes a transmission light receiving element 37 that receives a light pulse signal S1 via an optical fiber 41;
A pulse generation circuit 34 that generates a timing signal according to the optical pulse signal S1 and outputs it to the light projecting section 22; a transmission light projecting element 38 that projects a periodic optical pulse signal S2 in synchronization with the timing signal; It is characterized in that it is provided with an optical fiber 42 that transmits the optical pulse signal S2 to the next-stage photoelectric switch 32, and that the other photoelectric switches 32 and 32a are similarly configured. [Effect] Reliably prevents mutual interference between photoelectric switches.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention detects the presence or absence of an object by projecting light and detecting the presence or absence of reflected light. The present invention relates to a photoelectric detection device in which a plurality of photoelectric switches for determination are sequentially arranged.

0002

[Conventional technology]

Photoelectric switches are used as a means of detecting the presence or absence of objects moving on conveyor lines, etc. It is known that This projects light onto the path of an object and The presence or absence of an object is determined by detecting the presence or absence of reflected light. It takes In photoelectric switches, projection light is used to reduce power consumption and prevent mutual interference. The light is emitted intermittently in a pulsed manner.

0003 FIG. 10 is an exploded perspective view showing an example of this type of conventional photoelectric switch. The photoelectric switch is a so-called optical fiber type switch, and mainly consists of main unit 1 and detection switch. It consists of two exits. The main body 1 has a case 3 and a power supply built into the case 3. A circuit board 5 to which wiring 4 such as a cable or an output cable is connected, and this circuit board 5, the detection light emitting element 6, the detection light receiving element 7, and the upper part of the case 3 are covered. , the top plate 10 to which the indicator light 8 and adjustment knob 9 are attached, and the side of the case 3. and has insertion holes 11 and 12 facing the light emitting element 6 and the light receiving element 7. It consists of 13. On the other hand, the detection unit 2 is arranged facing the detected object 14. One end is connected to the detection head 15, and the other end is connected to the insertion hole 11, a pair of optical fibers 16 connected to the light emitting element 6 and the light receiving element 7 via 12; It has become. In conventional photoelectric switches like this, a timing signal of a predetermined period is used. When the sensing light is intermittently output from the light emitting element 6 in response to the The light is guided through the fiber 16 and projected from the detection head 15 onto the object to be detected 14 . child When the light reflected by the object to be detected 14 enters the detection head 15, this reflected light becomes a light The light is guided through the fiber 16 and received by the light receiving element 7, and as a result of this light reception, the circuit board 5 outputs a detection signal via wiring 4. On the other hand, when there is no detected object 14, Since the emitted light is not received by the light receiving element 7, a detection signal is output from the circuit board 5. I don't feel strong.

0004 FIG. 11 is an exploded perspective view showing another example of a conventional photoelectric switch. The switch is a so-called lens type switch, and the optical fiber shown in FIG. The main difference is the detection part compared to the type one, and the output from the detection light emitting element 17 is The pulsed light is projected onto the object to be detected 14 through the projection lens 18, and the object to be detected 14 is The reflected light is received by the detection light receiving element 20 via the light receiving lens 19. It has become.

[0005] Usually, there is not only one photoelectric switch for detecting the presence or absence of an object, but also other photoelectric switches. Multiple photoelectric switches are used for this purpose. For example, on a conveyor line A photoelectric switch that emits light from the side and a photoelectric switch that emits light from below. H, multiple photoelectric switches are installed in one place, such as a photoelectric switch that emits light from above. In addition to detecting the presence or absence of an object, it can also simultaneously detect the presence or absence of a label affixed to the object. (hereinafter, this projected light is referred to as sensing light). death However, by arranging multiple photoelectric switches close to each other or in close contact with each other in one place like this, And when each photoelectric switch emits light continuously, each photoelectric switch emits light from other photoelectric switches. There is a possibility that the sensing light projected by the switch may also be received. This is the mutual interference mentioned above. However, with photoelectric switches, the light emission timing does not overlap with other photoelectric switches. In addition to intermittent light emission, the reflected light from the self-emission and other photoelectric switches Means is provided for distinguishing the light (interference light) received by the projection of the light.

[0006] FIG. 8 is a block diagram showing a conventional photoelectric switch, in which 21 is a periodic pulse generator. Raw circuit, 22 is a light emitter, 23 is a light receiver, 24 is a gate circuit, 25 is an integration circuit, 2 6 is a determination circuit. For example, the pulse generating circuit 21, the gate circuit 24, the integrating circuit The circuit 25 and the determination circuit 26 are provided on the circuit board 5, and the light projecting section 22 is provided on the circuit board 5. The light receiving section 23 is made up of the light receiving element 7 and the like.

[0007] In FIG. 8, a periodic pulse generation circuit 21 always generates a pulse P1 of a constant period. The light emitting unit 22 is driven by this pulse P1, and has the same period as this pulse P1. , the sensing light is projected in a pulsed manner at a duty ratio. This sensing light is an object (not shown), the reflected light is received by the light receiving section 23, and the pulse P2 is output. This pulse P2 is generated by reflected light from the light emitting unit 22 of its own. If it is obtained by If it is obtained by receiving sensing light from matching does not match. Therefore, the output pulse P2 of the light receiving section 23 gates the pulse P1. The pulse P2 is supplied to the gate circuit 24 which generates a pulse. Extract only the russ. The output pulse of the gate circuit 24 is converted into a pulse P1 by the integrating circuit 25. is captured at the timing of The circuit 26 determines that an object is present.

[0008] The sensing light projected onto an object from the light projection unit 22 is reflected by the object, but the sensing light is reflected by the object. The reflected light is scattered, and a part of the reflected light is received by the light receiving section 23. For this reason, the acceptance The amount of light received by the light section 23 is small. Therefore, it is necessary to create pulse P2 from a small amount of light. However, if the presence or absence of an object is determined for each pulse P2, the The accuracy of detecting the presence or absence of is low. For this purpose, an integrating circuit 25 is provided. , the pulse extracted by the gate circuit 24 is integrated, and judgment is made according to the magnitude of the integrated value. is being carried out. This integrating circuit 25 may be an analog integrating circuit, but , usually a pulse counter is used to determine the timing of pulse P1 from the gate circuit 24. The determination circuit 26 determines the count value when, for example, eight pulses are supplied consecutively. It is determined that there is an object.

[0009] In such a photoelectric switch, the output pulse P1 of the periodic pulse generation circuit 21 If the duty ratio of is made sufficiently small compared to the period, the probability of mutual interference will be low. It also reduces power consumption. However, each photoelectric switch is completely independent, Furthermore, the period of light projection of each photoelectric switch is usually almost equal. For this reason, 2 In some cases, the light emission timings of two or more photoelectric switches overlap. This way In such a case, other photoelectric switches may be activated even though there is no object in Figure 8. By emitting light, a pulse whose timing coincides with pulse P1 is output from the light receiving section 23. P2 is output. Such a pulse P2 cannot be removed by the gate circuit 24, Therefore, an error will occur in determining the presence or absence of an object.

0010 An example of a technique for preventing such mutual interference is disclosed in Japanese Patent Publication No. 60-51043. has been done. This is because the interference identification circuit 27 is connected to the gate circuit 24 as shown in FIG. Identify whether the output pulse is due to interference light or not, and identify whether the output pulse is due to interference light or not. When the pulse generation circuit 21a is controlled by the phase shift circuit 28, the pulse generation circuit 21a is Advance or delay the phase of pulse P1.

[0011] In addition, in Japanese Patent Application Laid-open No. 61-138192, a pulse is generated by receiving interference light. Extract the pulse signal and generate a pulse with the same frequency and different phase as this pulse signal. Drives the light emitter so that it emits light at the same frequency as the interference light but with a different phase. The technology has been disclosed.

0012 Furthermore, in Japanese Patent Application Laid-Open No. 63-263917, When a pulse is obtained from the light receiving section, the emission period is sequentially shifted from the reference period, A technique that returns the emission period to the original standard period when a predetermined number of such pulses are obtained. technique has been disclosed. According to this, other photoelectric switches with approximately the same light emitting period as the self When the light emission timing of the switch matches the self-emission timing, the light is emitted from the receiver. Since pulses that match the optical timing are obtained, the self-emitting period changes sequentially. go. On the other hand, the light emission periods of the other photoelectric switches do not change. Therefore, self The light emitting timing of oneself is different from the light emitting timing of other photoelectric switches, and this Pulses from the light receiving section due to light from other photoelectric switches are removed by the gate circuit. However, the light receiving section receives the light emitted by itself, and this causes the light receiving section to The output pulse matches the self-emission timing. The number of such pulses is Once the number is obtained, the self-emitting period returns to the original reference period. However, at this time Due to the above operation, the own light emission timing may deviate from the previous light emission timing. Therefore, the light emitting timing will be different from that of other photoelectric switches. Ru.

[0013]

[Problem that the idea aims to solve]

All of the above-mentioned conventional technologies are able to adapt to other photoelectric switches by shifting the light emission timing. The aim is to prevent mutual interference with switches and photoelectric switches installed in one location. This is quite effective when the number of switches is small. However, many photoelectric When installing switches in one place, these photoelectric switches must be used to eliminate mutual interference. At least this The difference in the light emission timing of these photoelectric switches is slight, and for this reason, Even if the light emitting timing of two photoelectric switches match, their light emitting If the timing is shifted, it will match the light emission timing of other photoelectric switches, Mutual interference cannot be completely prevented.

[0014] In addition, each photoelectric switch is equipped with mutual interference prevention means as described above. In the case of multiple photoelectric switches where mutual interference occurs, the light emitting timing is shifted. will be done. In this case, make sure that there is no mutual interference due to these shifts. In order to It will be very difficult to determine them.

[0015] Furthermore, the above conventional technology requires mutual interference prevention means with a complicated circuit configuration. .

[0016] The purpose of this invention is to sequentially operate multiple photoelectric switches installed at one location. The object of the present invention is to provide a photoelectric detection device that can perform the following.

[0017]

[Means to solve the problem]

In order to achieve the above object, the present invention provides a self-contained A detection light emitting element that intermittently projects sensing light and the reflected light reflected from the object to be detected. and a detection light-receiving element that receives the sensing light, the timing of which coincides with the sensing light. Multiple photoelectric switches are placed in close proximity to determine the presence or absence of an object based on the presence or absence of light pulses. Alternatively, in a photoelectric detection device arranged closely together, the photoelectric switch includes: A transmission receiver that receives periodic optical pulse signals transmitted via a transmission optical fiber. an optical element, and a synchronization timing that synchronizes with the optical pulse signal based on the optical pulse signal. a delayed timing signal that is delayed by a predetermined time from the optical pulse signal or the optical pulse signal. a signal generating means for generating and outputting the signal to the detection light projecting element; and the synchronization timing signal. Or transmission that projects a periodic optical pulse signal in synchronization with the delayed timing signal. The optical pulse signal projected from the transmitting transmitting transmitting element is transmitted to the next stage photoelectric switch. The configuration includes another transmission optical fiber for transmitting data to the switch.

[0018]

[Effect]

Since the present invention is configured as described above, the periodic optical pulse signal is transmitted through the transmission optical fiber. is transmitted to a photoelectric switch via a signal generating means. A detection light emitting element that generates a synchronized timing signal or delayed timing signal. Output to. and the synchronization timing signal or delay signal from the detection light emitting element. Sensing light is intermittently projected according to a timing signal, and the sensing light is reflected by the object to be detected. The reflected light is received by a detection light receiving element, and the timing matches the sensing light. The presence or absence of an object is determined based on whether or not a light pulse is received. In addition, the photoelectric switch , the synchronized timing signal or the delayed timing signal is transmitted by the transmitting light emitting element. A light pulse signal is projected synchronously, and this light pulse signal is transmitted via another transmission optical fiber. The light is then transmitted to the transmission light receiving element of the next stage photoelectric switch. Then, the next stage photoelectric The switch also determines the presence or absence of an object as described above. By this Thus, a plurality of photoelectric switches installed at one location can be sequentially activated.

[0019]

【Example】

Hereinafter, embodiments of the photoelectric detection device of the present invention will be described based on the drawings. FIG. 1 is a perspective view showing a first embodiment of the photoelectric detection device of the present invention, and FIG. 2 is a perspective view showing the photoelectric detection device of the present invention. A perspective view showing a photoelectric switch included in the detection device, FIG. 3 is a diagram showing the photoelectric switch of FIG. 2. 4 is a sectional view taken along line A-A in FIG. 3, and FIG. 5 is a block diagram of the photoelectric switch in FIG. 2. This is a diagram. In addition, in FIG. 5, the same as that shown in FIG. 8 mentioned above is used. are given the same reference numerals. That is, 22 is a light emitter, 23 is a light receiver, and 24 is a game. 25 is an integration circuit, and 26 is a determination circuit.

[0020] The photoelectric detection device shown in FIG. 1 includes a photoelectric switch 31 and a The next-stage photoelectric switch 32 and the further next-stage photoelectric switch 32a are arranged in sequence. ing. For example, the photoelectric switch 31 has the basic configuration as shown in FIG. It is similar to the conventional one shown in FIG. It has an integrating circuit 25 and a determining circuit 26, but also has a periodic optical pulse signal. A transmission light receiving section 33 receives the optical pulse signal S1, and a transmission light receiving section 33 receives the optical pulse signal S1. A synchronous timing signal that is synchronized with the optical pulse signal S1 or a position that is earlier than the optical pulse signal S1. A signal that generates a delayed timing signal delayed by a certain period of time and outputs it to the light projecting section 22. A pulse generation circuit 34 as a generation means and the synchronization timing signal or the delay A periodic optical pulse signal S2 is sent to the next stage photoelectric switch 32 in synchronization with the timing signal. A transmitting light projector 35 for transmitting the information is provided.

[0021] The transmission light receiving section 33 protrudes from the upper part of the case 36, as shown in FIG. The transmitting light receiving element 37 is composed of a transmitting light receiving element 37, and the transmitting light projecting section 35 is also formed from the upper part of the case 36. It consists of a projecting transmission light projecting element 38. The upper part of the case 36 is made of transparent material. A cap 39 having a cap 39 is removably provided, and this cap 39 is attached to the receiver. a protrusion 40 that accommodates the optical element 37 and the light projecting element 38; a transmission optical fiber 41; 42 is provided. This holding part 43 is inserted through a screw 44. The optical fibers 41 and 42 are fixed to the holding part 43 by the fastening fixture 45. It is designed to be set. On the other hand, the light projecting section 22 is a diagram built in the case 36. A detection light emitting element (not shown) and a detection optical fiber 46 connected to this light emitting element , and a detection head (not shown) provided at the tip of this optical fiber 46. The recording light-receiving section 23 also includes a detection light-receiving element (not shown) built into the case 32 and this receiver. Another detection optical fiber 46a connected to the optical element and the tip of this optical fiber 46a and the detection head provided at the end. In addition, other photoelectric switches 32 , 32a are similarly configured. Then, the photoelectric switch 31 and the photoelectric switch 3 2 is connected via the optical fiber 42, and similarly, the photoelectric switch 32 and the photoelectric switch 32 are connected via the optical fiber 42. It is also connected to the switch 32a via an optical fiber 47. In addition, for the above-mentioned detection While the light emitted from the light emitting element is called sensing light, the light emitted from the light emitting element 38 for transmission is called sensing light. The optical pulse signal projected from the transmitter will be referred to as transmitted light.

[0022] In this first embodiment, the transmitted light, that is, the periodic optical pulse signal S1 is When transmitted to the photoelectric switch 31 via the fiber 41, this photoelectric switch 31 The optical pulse signal S1 is received by the transmission light receiving element 37, and the pulse generating circuit 3 receives the optical pulse signal S1. 4, a synchronizing circuit synchronizes with the optical pulse signal S1 based on the optical pulse signal S1. Timing signal or delay timing delayed by a predetermined time from the optical pulse signal S1 The detection signal is generated and output to the detection light projector 22. Along with this, the detection light emitter 22 is a sensing sensor according to the synchronized timing signal or the delayed timing signal. The scanning light is intermittently projected through the optical fiber 46 and the detection head. child At this time, the reflected light reflected by the object to be detected is transmitted through the detection head and the optical fiber 46a. The light is received by the detection light receiving section 23, and the gate circuit 24 and the integrating circuit 25 perform a predetermined operation. After processing in this order, the determination circuit 26 determines whether the timing matches the sensing light. The presence or absence of an object is determined based on the presence or absence of received light pulses. In addition, the transmission light emitter 35 generates an optical pulse in synchronization with the synchronous timing signal or the delayed timing signal. The transmission signal S2 is projected from the transmission light projecting element 38. Next, the optical pulse signal S2 is Since it reaches the next stage photoelectric switch 32 via the fiber 47, the next stage photoelectric switch The switch 32 also determines the presence or absence of an object as described above according to the optical pulse signal S2. At the same time, an optical pulse signal is output to the next-stage photoelectric switch 32a. ing.

[0023] In the embodiment configured in this way, a plurality of photoelectric switches 31 installed in one place , 32, 32a can be activated sequentially. Also, in this example, the optical fiber For example, since the photoelectric switches are configured to be connected via a Even if there is an obstacle 48 between the switches 31 and 32, these photoelectric switches 31 and 3 2 are placed apart from each other, and the optical pulse signals are transmitted through the optical fiber 42. Even if the photoelectric switch 32 is attached to the movable body 49, Optical pulse signals can be transmitted via optical fiber 47. Note that this example Here, we will exemplify the case of a photoelectric detection device consisting of three photoelectric switches 31, 32, and 32a. However, the present invention is not limited to this. Even if photoelectric detection devices such as can be moved.

[0024] FIG. 6 shows a photoelectric switch included in the second embodiment of the photoelectric detection device of the present invention. 7 is an assembled perspective view showing the photoelectric switch of FIG. 6. FIG.

[0025] The photoelectric detection device shown in FIG. 6 includes a photoelectric switch 51 and a photoelectric switch 51. A photoelectric switch (not shown) at the next stage is arranged. For example, the photoelectric switch 51 The basic configuration is the same as that of the first embodiment, and as shown in FIG. Light projecting section 22, light receiving section 23, gate circuit 24, integrating circuit 25, and determination circuit 26 , a transmission light receiving section 33, a pulse generation circuit 34 as a signal generation means, a transmission light projecting section It is equipped with 35. The transmission light receiving section 33 provided in this embodiment is shown in FIG. As shown in FIG. The transmitting light receiving element 54 has a light receiving axis, and the transmitting light projecting section 34 is also connected to the circuit board 5. 3, and consists of a transmitting light emitting element 55 having an upward light emitting axis. . A light-transmitting key is attached to the upper part of the case 52 via a light-transmitting top plate 56. A cap 57 is removably provided. The protrusion 58 of the cap 57 has a transmission Semi-cylindrical grooves 61 and 62 with which the transmission optical fibers 59 and 60 engage, respectively, are arranged in the upper and lower directions. It is formed in the direction. A fixture 64 is fastened to the protrusion 58 via a screw 63. With this fixture 64, each optical fiber 59, 60 is connected to the light receiving element 54 and the emitter. The optical fibers 59 and 60 are fixed to the protrusion 58 while facing the optical element 55. It has become so. On the other hand, the light projecting unit 22 is built in the case 52 and is shown in FIG. a detection light emitting element connected to this light emitting element, and a detection optical fiber 65 connected to this light emitting element. and a detection head (not shown) provided at the tip of the optical fiber 65. The light section 23 also includes a detection light receiving element (not shown) built into the case 52 and this light receiving element. Another detection optical fiber 65a connected to and the detection head provided. Other photoelectric switches are configured similarly. It is.

[0026] Even in this second embodiment, the periodic optical pulse signal S1 passes through the optical fiber 59. When the optical pulse is transmitted to the photoelectric switch 51, the optical pulse is transmitted to the photoelectric switch 51. The transmission signal S1 is received by the transmission light receiving element 54 via the cap 57 and the top plate 56. , the presence or absence of an object is determined using the same procedure as in the first embodiment. And transmission light The element 55 emits light in synchronization with the synchronous timing signal or the delayed timing signal. The pulse signal S2 is projected through the top plate 56 and the cap 57, and is connected to the optical fiber 60. The signal is sent to the transmission light-receiving element of the next-stage photoelectric switch 42 via . And the next The second photoelectric switch 42 also detects the presence or absence of an object as described above in response to the optical pulse signal S2. It is designed to judge.

[0027] The second embodiment configured in this manner also has the same effect as the first embodiment described above. Obtainable.

[0028]

[Effect of the idea]

Since the present invention is configured as described above, multiple photoelectric switches can be installed in one place. can be activated sequentially by transmitting optical pulse signals, thus the circuit configuration light emission timing between photoelectric switches without the need for complicated mutual interference prevention measures. mutual interference between groups can be reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first embodiment of a photoelectric detection device of the present invention.

FIG. 2 is a perspective view showing a photoelectric switch of the photoelectric detection device of FIG. 1;

FIG. 3 is a plan view of the photoelectric switch of FIG. 2;

FIG. 4 is a sectional view taken along line AA in FIG. 3;

FIG. 5 is a block diagram of the photoelectric switch of FIG. 2;

FIG. 6 is an exploded perspective view showing a photoelectric switch included in a second embodiment of the photoelectric detection device of the present invention.

FIG. 7 is an assembled perspective view of the photoelectric switch of FIG. 6;

FIG. 8 is a block diagram showing an example of a conventional photoelectric switch.

FIG. 9 is a block diagram showing another example of a conventional photoelectric switch.

FIG. 10 is an exploded perspective view showing an optical fiber type photoelectric switch.

FIG. 11 is an exploded perspective view showing a lens-type photoelectric switch.

[Explanation of symbols]

22 Light projection part 23 Light receiving part 31, 32, 32a Photoelectric switch 33 Transmission light receiving section 34 Pulse generation circuit (signal generation means) 35 Transmission light projection part 37 Transmission light receiving element 38 Transmission light emitting element 39 Cap 41, 42, 47 Transmission optical fiber 54 Transmission light receiving element 55 Transmission light emitting element 56 Top plate 57 Cap 59, 60 Transmission optical fiber

──────────────────────────────────────────────── ─── Continuation of front page (72) Creator Ikuro Ouchi 60-2 Shimomachi, Yoshioka, Yamato-machi, Kurokawa-gun, Miyagi Prefecture

Claims (1)

[Scope of utility model registration request] 1. A detection light projecting element that intermittently projects sensing light in accordance with a timing signal of a predetermined cycle; and a detection light receiving element that receives reflected light reflected by an object to be detected; In a photoelectric detection device in which a plurality of photoelectric switches are arranged close to each other or closely arranged to determine the presence or absence of an object based on whether or not an optical pulse whose timing coincides with the sensing light is received, the photoelectric switch is connected to the photoelectric switch via a transmission optical fiber. a transmission light-receiving element that receives a periodic optical pulse signal transmitted by the optical pulse signal; and a synchronization timing signal that synchronizes with the optical pulse signal based on the optical pulse signal or a delay timing that is delayed by a predetermined time from the optical pulse signal. a signal generating means for generating a signal and outputting it to the detection light projecting element; a transmission light projecting element that projects a periodic optical pulse signal in synchronization with the synchronous timing signal or the delayed timing signal; 1. A photoelectric detection device characterized by being provided with another transmission optical fiber for transmitting an optical pulse signal projected from a light projecting element to a next-stage photoelectric switch.