JPH06249969A - Photoelectric switch and detecting method - Google Patents

Abstract

PURPOSE:To allow the detection of a transparent bottle and the content thereof using a single photoelectric switch. CONSTITUTION:A light projector is disposed normally to the passing direction of a transparent bottle and a light receiver is disposed oppositely therein. The light receiver comprises a split photodiode 12 having a pair of outputs for detecting the light moving along the passing direction of the transparent bottle. The difference between the pair of outputs is detected by a differential amplifier circuit 14 and discriminated by comparator circuits 15, 16 having positive and negative threshold values. The presence of bottle is detected when both comparator circuits produce outputs. The presence of content in the bottle is decided based on the sequence of outputs from the comparator circuits 15, 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric switch for determining whether a transparent bottle has passed or not and the contents thereof.

[0002]

2. Description of the Related Art Conventionally, as a photoelectric switch for detecting the passage of a transparent bottle and the presence / absence of contents, two photoelectric switches for detecting a bin and a photoelectric switch for distinguishing contents are used as shown in FIG. Was. FIG. 8 is a schematic view showing a usage state of such a photoelectric switch, which is composed of two transmission type photoelectric switches. When the transparent bin has passed, the light receiving output level of the photoelectric switch is divided into a level with contents, a level without contents, and a level without bins. For this reason, two photoelectric switches that independently set these thresholds are used to discriminate the passage of the bin and the presence or absence of the contents.
Then, the photoelectric switch 102 for detecting the contents is operated only when the bin detection photoelectric switch 101 outputs a switch to determine the presence or absence of the contents.

[0003]

Since the two photoelectric switches are used as described above, there is a drawback in that the labor and space for mounting are required and the maintenance is also laborious. Moreover, since it is necessary to determine the presence or absence of the contents at the timing when the bin is detected, the controller 103 is required in addition to the photoelectric switch. Further, the light amount is not so large and does not change depending on the presence or absence of the contents. Therefore, there is a drawback that the characteristics of the photoelectric switch change depending on the temperature and the lens surface is easily affected, and it is difficult to surely detect.

The present invention has been made in view of the above conventional problems, and detects the movement of light rather than the light receiving level of light, so that only one photoelectric switch can pass through the bin and the contents. The technical issue is to be able to reliably detect the presence or absence of.

[0005]

According to the invention of claim 1 of the present application, a transparent projector is arranged laterally of the passage, and a projector for radiating light toward the passage and a projector are arranged so as to face the projector. A photodetector, which is a photoelectric switch for transparent bin detection, comprising: a photodetector, the photodetector being arranged along a passing direction of the transparent bin, and having a pair of outputs for detecting light moving in the passing direction; The passage of the transparent bin is detected by the comparison outputs obtained from both the first and second comparison circuits for discriminating the respective outputs of the light receiving elements at a predetermined threshold level and the first and second comparison circuits. A bin passage detecting means; and a content discriminating means for discriminating the presence or absence of the content based on the order of outputs of the first and second comparison circuits when an output is obtained from the bin passage detecting means. It is a feature.

The invention according to claim 2 of the present application has a light projector which is arranged on the side of the passage of the transparent bottle and irradiates the light toward the passage, and a light receiver which is arranged opposite to the projector. A photoelectric switch for detecting a transparent bottle, wherein a light receiver is arranged along the passage direction of the transparent bottle and has a pair of outputs for detecting light traveling in the passage direction, and a pair of outputs of the light receiving element. Both the first and second comparison circuits for discriminating the outputs of the differential amplification circuit by the thresholds having the same positive and negative absolute values, and the first and second comparison circuits. Based on the order of the outputs of the first and second comparison circuits when the output is obtained from the bin passage detection means, the content of the bin passage detection means for detecting the passage of the transparent bin by the comparison output being obtained. And a contents discriminating means for discriminating the presence or absence of It is an feature.

According to the invention of claim 3 of the present application, there is provided a light projector which is arranged on the side of the passage of the transparent bottle and emits light toward the passage, and a light receiver which is arranged so as to face the light projector. A photoelectric switch for detecting a transparent bin, wherein a light receiver is arranged along the passage direction of the transparent bin, and divides the output of the light receiving element and a light receiving element having a pair of outputs for detecting light moving in the passage direction. A division circuit for performing division, and first and second comparison circuits for discriminating the output of the division circuit by a predetermined value around 1;
Bin passage detection means for detecting passage of a transparent bin by obtaining comparison outputs from both the second comparison circuits, and outputs of the first and second comparison circuits when outputs are obtained from the bin passage detection means. And a content discriminating means for discriminating the presence or absence of the content based on the order of.

[0008]

According to the invention of claim 1 of the present application having such a feature, light is emitted from the projector perpendicularly to the passage direction of the passage of the transparent bottle, and is opposed to this along the passage direction of the transparent bottle. The moving light is detected by the light receiving element of the light receiver. When outputs are obtained from the pair of output terminals of the light receiving element, the light reception outputs are discriminated by the first and second comparison circuits, and when outputs are obtained from any of these comparison circuits, the bin passage detecting means is used. Detects passage of clear bottles. When the bin containing the contents passes, the output from the projector is refracted by the contents of the bin, and the light moves in the same direction as the bin. Also, when a bottle without contents passes, the light is refracted in the direction opposite to the moving direction of the bottle. Therefore, the content discriminating means discriminates the presence or absence of the content on the basis of the output order of the first and second comparison circuits.

According to the second aspect of the present invention, the difference between the pair of outputs of the light receiving element is calculated by the differential amplifier circuit,
The second comparison circuit sets thresholds having the same positive and negative absolute values, respectively. In this case as well, it is possible to detect the passage of the bin when the outputs are successively obtained from both the comparison circuits, and determine the presence or absence of the contents by the order of the outputs.

According to the invention of claim 3 of the present application, the difference between the pair of outputs of the light receiving element is divided by the division circuit, and the first and second comparison circuits having the threshold value around 1 based on the division value. Are discriminated by. In this case as well, it is possible to detect the passage of the bin when the outputs are successively obtained from both the comparison circuits, and determine the presence or absence of the contents by the order of the outputs.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the detection principle used in the photoelectric switch according to the present invention will be described. FIG. 2A is a ray tracing diagram showing the refraction of light in a cylindrical transparent glass bottle 1 when the contents such as water are contained in the cylindrical transparent glass bottle 1 and parallel light is refracted in the bottle.
FIG. 2B is a ray tracing diagram in the case where the bottle does not contain water but only air. As shown in these figures, when parallel light is incident from the left side, it has the effect of a convex lens that focuses the light if water is contained, and if the parallel light is incident from the left side of the concave lens that diffuses light. effective. This is caused by the difference in refractive index between water and air.

A mounting method in the case of performing detection using such a lens effect will be described with reference to FIG. In this figure, a large number of transparent bottles 1 pass on a belt conveyor 2. Then, a projector 3 of a photoelectric switch for irradiating light perpendicularly to the passage direction is provided on the side of the passage of the transparent bottle 1.
When the contents are put in, the irradiation position of this light is arranged so as to penetrate the position. Further, the light receiver 4 is arranged at a position facing the projected beam.

Now, FIG. 4A is a diagram showing a change in light when a transparent glass bottle containing contents such as water moves on the belt conveyor 2. In this figure, it is assumed that the bottle 1 is observed from above the belt conveyor 2, and the bin 1 advances from the upper side to the lower side in the figure as indicated by the arrow. When parallel light is radiated from the side of the bin 1 perpendicularly to the moving direction of the belt conveyor 2, the bin 1 first reaches the position P1 in the figure. In this case, if there is contents, the light passes through the end of the bin 1 on the traveling direction side as shown in FIG. 2A, so that the light is refracted in the R1 direction of FIG. 4A. Then, when the bin 1 reaches the position of P2, the light goes straight like R2. When the bin 1 further advances and reaches the position of P3, light is emitted by grazing the direction opposite to the direction in which the bin 1 is moving, so that the light is refracted downward in the figure, that is, in the R3 direction.
Therefore, when viewed from the light receiving side, the light also moves in the traveling direction of the bin 1 as the bin 1 passes.

FIG. 4 (b) shows a state in which the bottle 1 containing no contents passes in the same manner. In this case, when the bin 1 is at the position P1, it is refracted in the R1 direction as shown in FIG. 4 (b). The light travels straight at the position P2, and is refracted in the direction R3 at the position P3. Therefore, when viewed from the light receiving side, the light travels in the direction opposite to the traveling direction of the bin when the bin 1 passes.

As described above, the light on the light receiving side moves in the same direction or in the opposite direction to the traveling direction of the work depending on the presence / absence of the contents, and therefore it is possible to determine the passage of the bin and the presence / absence of the contents based on this change.

Next, an embodiment of the photoelectric switch according to the present invention will be described with reference to the block diagram. FIG. 1 is a block diagram showing the configuration of a photoelectric switch according to an embodiment of the present invention. As shown in FIG. 3, the light projector 3 is arranged at a position facing the light receiver 4 via the belt conveyor 2, and is configured by using a light emitting diode 11 that irradiates the central region of the light receiver 4 with light and an optical system member (not shown). To be done. As shown in FIG. 4, the light receiver 4 is a two-divided photodiode 12A, 12B for detecting light moving along the moving direction of the work at a position facing the light beam of the light projector 3 as a light receiving element.
Is provided. These photodiodes 12A, 12
The outputs of _B are converted into voltage signals V _A and V _B by I / V converters 13A and 13B, respectively, and given to the differential amplifier circuit 14. The differential amplifier circuit 14 is an amplifier circuit for amplifying the difference between the outputs V _A and V _B , and outputs a positive voltage signal when V _A > V _{B and} a negative voltage signal when V _A <V _B. It is given to the first and second comparison circuits 15 and 16. The first comparison circuit 15 is set with a threshold value Vth1 of a predetermined positive level, and the second comparison circuit 16 is set with a predetermined threshold value Vth2 of a negative value whose absolute value is equal to the threshold value Vth1. And an H level signal is output when the input changes in the negative direction.
The output of the comparison circuit 15 is given to the reset input terminal of the RS flip-flop 17 and the set input terminal of the RS flip-flop 18. The output of the comparison circuit 16 is the set input terminal of the RS flip-flop 17, the RS flip-flop 19
Is given to the set input end of. Flip flop 1
The Q outputs of 8 and 19 are given to the AND circuit 20, and the logical product output thereof is given to the monostable multivibrator (MM) 22 via the delay circuit 21. The monostable multivibrator 22 outputs a signal obtained by delaying an input signal for a fixed time, and its output is given to an AND circuit 23 and an output circuit 24. The output circuit 24 is an output circuit that outputs a bin detection signal. The Q output of the RS flip-flop 17 is applied to the other input terminal of the AND circuit 23, and the output thereof is output as a content detection signal via the output circuit 25. Here, RS flip-flops 18, 1
The AND circuit 20, the delay circuit 21, the monostable multivibrator 22 constitute a bin passage detecting means for detecting the passage of the transparent bin when the comparison outputs are obtained from both the first and second comparison circuits. ing. RS flip-flop 17
The AND circuit 23 constitutes content discriminating means for discriminating the presence / absence of the content according to the output order of the first and second comparing circuits when the output is obtained from the bin passage detecting means.

Next, the operation of this embodiment will be described with reference to a time chart. 5A to 5K are waveform charts showing the waveforms of the respective portions a to k in FIG. In this figure, a period T1 shows an operation when a bin containing contents passes, and a period T2 shows a state when a bottle without contents passes. As described above, if the bin with contents passes through the detection area, first the I / V converter 13
The output V _A of the A side becomes large, then the I / V converters 13
Since the output V _B of the B side is increased, a signal indicating a differential amplifier circuit 14 in FIGS. 5 (a) is obtained. Therefore, FIG.
As shown in (b) and (c), the differential output is output from the comparison circuit 15 at time t ₁ when Vth ₁ exceeds Vth ₁ , and then output from the comparison circuit 16 at time t ₂ . With these outputs, the RS flip-flop 18 is first set at the time t ₁ , and then the RS flip-flops 17 and 19 are set at the time t ₂ of the output of the comparison circuit 2. Therefore, the AND circuit 20 outputs the logical product signal of the flip-flops 18 and 19 as shown in FIG.
1 through the monostable multivibrator 22 through FIG.
It is output as shown in (i). This signal is the comparison circuit 1
It is obtained from exceeding the threshold values of both 5 and 16 and is output from the output circuit 24 as the bin passing signal k.

Further, depending on this signal and the state of the RS flip-flop 17, a detection signal of the contents is output. That is, in FIG. 5, the comparison circuit 15 and then 16 are turned on when the bin having the contents passes during the period T1, so that the flip-flop 17 is in the set state after the passage.
Therefore, in this case, since the AND condition by the AND circuit 23 is satisfied, the signal j indicating the presence of the contents is output from the output circuit 25.

Further, in the period T2 shown in FIG. 5, if the bin containing no content passes, the comparator 15 outputs the output after the output of the comparator 16, so that after the bin containing no content passes. The Q output of the flip-flop 17 is at L level. Therefore, the AND condition is not satisfied in the AND circuit 23, and no output is output from the output circuit 25. In this way, the passage of the bottle and the presence / absence of the contents can be determined by the movement direction of the optical system.

Next, a second embodiment of the present invention will be described. FIG. 6 is a block diagram showing a configuration of a main part of a transparent bottle photoelectric switch according to a second embodiment of the present invention. The same parts as those in the first embodiment described above are designated by the same reference numerals and detailed description thereof will be omitted. . The projector 31 in this embodiment is the oscillator circuit 3
2 and a transistor 33 for driving the light projecting element 11 by its output. The oscillating circuit 32 periodically applies a light emitting pulse to the drive transistor 33 and also causes the light receiver 3 to receive light.
A gate signal is given to the signal processing circuits 35 and 36 in the circuit 4. The photodetector 34 side has the two-divided photodiode 22, I / V converters 13A and 13B, the differential amplifier circuit 14 and the comparison circuits 15 and 16 as in the first embodiment.
The outputs are given to the signal processing circuits 35 and 36, respectively.
The signal processing circuits 35 and 36 output signals to the RS flip-flops 17 to 19 when the output of the oscillator circuit 32 continuously outputs the output of the comparison circuit a plurality of times. The circuit configuration of the RS flip-flops 17 to 19 and subsequent ones is the same as that of the first embodiment, and is therefore omitted in FIG. In this embodiment, it is necessary to connect the light projector 31 and the light receiver 34 in order to transmit a light projection pulse as shown in the drawing.

Next, the operation of this embodiment will be described. 7A to 7F are time charts showing the waveforms of the respective portions a to f in FIG. In this embodiment, a light projecting pulse is oscillated as shown in FIG. 7A, and the light projecting element 11 is driven based on this signal. This signal is received by the two-division photodiode 12 as in the first embodiment, and I /
The voltage signals are converted by the V converters 13A and 13B. As the output of the differential amplifier circuit 14, a signal shown in FIG. 7B is obtained depending on the passing direction of the object. FIG. 7B shows the threshold values Vth1 and Vth2 of the comparison circuits 15 and 16 together with their hysteresis. ) Signal is output. And the signal processing circuit 3
Reference numerals 5 and 36 are output as shown in FIGS. 7D and 7F, respectively, when the comparison circuits 15 and 16 output a plurality of times, for example, four times in succession, in synchronization with the light projection pulse. . The operation of the signal processing circuits 35 and 36 and thereafter is similar to that of the first embodiment described above. In this case, it is necessary to electrically connect between the light emitter and the light receiver, but since it is possible to extract only the signal synchronized with this using the oscillation circuit, it is possible to improve noise resistance.

Although each of the above-described embodiments uses the two-divided photodiode as a light receiving element, it is also possible to use a light receiving element such as a position detecting element for detecting light moving along the passage direction of the bin. . In the above-described embodiment, the difference between the outputs of the I / V converters is detected by using the differential amplifier circuit, and the light passage direction is detected by the output order of the two comparison circuits having the positive and negative threshold values. Inputs the output of the I / V converter to two comparison circuits having the same threshold level,
You may make it detect based on the order. Although the differential amplifier is used in the above-described embodiment, a pair of I /
The moving direction of the received light signal may be detected by dividing the output of the V converter and discriminating the divided value with a predetermined value before or after 1.

[0023]

As described in detail above, according to the first to fifth aspects of the present invention, the passage of the bottle and the presence / absence of the contents thereof are discriminated based on the moving direction of the light. Therefore, it is not necessary to dispose two photoelectric switches in parallel, and since the controller can be eliminated, the man-hours for mounting and maintenance can be reduced, and the mounting place can be easily selected. it can. Furthermore, it is less susceptible to the temperature characteristics of the photoelectric switch and dirt on the lens,
The excellent effect that the bottle and the contents can be detected stably can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transparent bin detecting photoelectric switch according to a first embodiment of the present invention.

FIG. 2 illustrates tracking refracted light in a transparent bin for a light beam of the present invention.

FIG. 3 is a perspective view showing a usage state of the photoelectric switch according to the present embodiment.

FIG. 4 is a diagram showing passage of a transparent bin on a belt conveyor and changes in the refraction direction of light according to the present embodiment.

FIG. 5 is a time chart showing the operation of the first embodiment.

FIG. 6 is a block diagram showing a configuration of a transparent bin detecting photoelectric switch according to a second embodiment of the present invention.

FIG. 7 is a time chart showing the operation up to the signal processing unit of the second embodiment.

FIG. 8 is a perspective view showing a usage state of a conventional transparent bin detecting photoelectric switch.

[Explanation of symbols]

 1 Bin 3 Light emitter 4 Light receiver 11 Light emitting element 12 Two-divided photodiode 12A, 12B Photodiode 13A, 13B I / V converter 14 Differential amplification circuit 15, 16 Comparison circuit 17, 18, 19 RS flip-flop 20, 23 AND circuit 21 Delay circuit 22 Monostable multivibrator 24, 25 Output circuit 32 Oscillation circuit 33 Transistor 34, 35 Signal processing circuit

Claims (5)

[Claims] 1. A photoelectric converter for detecting a transparent bottle, comprising: a projector disposed on the side of the passage of the transparent bottle and irradiating light toward the passage; and a light receiver arranged opposite to the projector. A switch, wherein the light receiver is arranged along a passage direction of the transparent bin, and a light receiving element having a pair of outputs for detecting light moving in the passage direction, and each output of the light receiving element to a predetermined threshold value. A first and a second comparison circuit for discriminating based on a level; a bin passage detection unit for detecting passage of a transparent bin by obtaining comparison outputs from both the first and second comparison circuits; A photoelectric switch, comprising: a contents discriminating means for discriminating the presence or absence of contents based on the order of outputs of the first and second comparing circuits when an output is obtained from the detecting means. 2. A photoelectric converter for detecting a transparent bottle, comprising: a projector arranged laterally of the passage of the transparent bottle and irradiating light toward the passage; and a light receiver arranged opposite to the projector. A switch, wherein the photodetector is arranged along a passage direction of the transparent bin and takes a difference between a pair of outputs of the photodetector and a photodetector having a pair of outputs for detecting light moving in the passage direction. A differential amplifier circuit, a first and a second comparator circuit for discriminating outputs of the differential amplifier circuit by thresholds having the same positive and negative absolute values, and comparison by both of the first and second comparator circuits. Based on the output order of the first and second comparison circuits when the output is obtained from the bin passage detection means, a bin passage detection means for detecting passage of the transparent bin by the output being obtained. A content discriminating means for discriminating the presence or absence of Photoelectric switch, characterized by. 3. A photoelectric converter for detecting a transparent bottle, which has a light projector arranged on a side of the passage of the transparent bottle and irradiates light toward the passage, and a light receiver arranged to face the light projector. A switch, wherein the photodetector is arranged along a passage direction of the transparent bin, and a photodetector having a pair of outputs for detecting light moving in the passage direction, and a division for dividing an output of the photodetector A circuit, and a first circuit for discriminating the output of the division circuit with a predetermined value of around 1.
A second comparison circuit, a bin passage detection unit that detects passage of a transparent bin by obtaining comparison outputs from both the first and second comparison circuits, and an output obtained from the bin passage detection unit. A photoelectric switch characterized by comprising: a content discriminating means for discriminating the presence / absence of a content based on an output sequence of the first and second comparison circuits. 4. The light projector includes an oscillating circuit that oscillates in a predetermined cycle, and a light projecting element that is driven by an output of the oscillating circuit, and the light receiver is synchronized with an output of the oscillating circuit. 4. The photoelectric switch according to claim 1, further comprising a first signal processing circuit and a second signal processing circuit for extracting the outputs of the first and second comparison circuits, respectively. 5. A light receiving element for irradiating a light beam in a direction perpendicular to the passing direction of the transparent bottle and for receiving the light beam moving along the passing direction of the transparent bottle is arranged to sandwich the passing position of the transparent bottle. The light beam is received by, and the pair of outputs obtained from the light receiving element are compared at a predetermined threshold level, and the passage of the transparent bin is detected by the output obtained from the respective comparison outputs. A photoelectric switch detection method, wherein the presence or absence of the contents in the transparent bin is determined according to the order of the comparison output when passage is detected.