JPH05327453A - Photoelectric detecting device of wide viewfield and light emitting/receiving device therefor - Google Patents

Abstract

PURPOSE:To set the positional relation where a pair of light emitting/receiving devices can emit and receive the light with each other and to keep the even detecting sensitivity by disposing to face oppositely a pair of light emitting/receiving devices consisting of the same number of light emitting and light receiving elements respectively which are arrayed alternately and in the same number of rows. CONSTITUTION:A light emitting/receiving device 1 contains plural number of light emitting elements 2 and the same number of light receiving elements 3 and other electronic parts, etc., in a case 1a having the attachment holes 1b. Both elements 2 and 3 emit and receive the infrared beams respectively and arrayed linearly and alternately. An infrared filter 4 is provided at the front of both elements 2 and 3 to minimize the disturbances caused by the visible light beams. Then, a pair of devices 1 is placed with one of them turned by 180 deg. on the same plane so that the elements 2 and 3 set on a projecting surface oppose to the elements 2 and 3 of the devices 1 respectively with their optical axes coincident with each other. In such a constitution, the detecting sensitivity is decided by the arranging density of those elements 2 and 3 in their array direction in regard of the size of an object.

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, and more particularly to a wide-field photoelectric detection device for detecting a passing object in a wide field of view.

[0002]

2. Description of the Related Art FIG. 9 is a perspective view showing a conventional wide-field photoelectric detection device. The projector 51 contains a plurality of light emitting elements (not shown) aligned in the vertical direction of the figure, and the light receiver 52 has a plurality of light receiving elements (see the figure) arranged according to the optical axes of the light emitted from these light emitting elements. (Not shown). For example, when the light A emitted from a certain light emitting element is blocked by the object 53 passing between the projector 51 and the light receiver 52, the light does not enter the corresponding light receiving element. Therefore, this state change can be replaced with an electric signal to obtain an object detection signal. If the object has a size equal to or larger than a predetermined value, basically all objects passing through the detection area B should be able to be detected.

[0003]

In the conventional wide-field photoelectric detection device as described above, the detection sensitivity is considerably different depending on where in the detection area B the object 53 passes. For example,
An object that passes through the light receiver 52 side can be reliably detected, but the detection sensitivity decreases as the object moves away from the light receiver 52 (closer to the light emitter 51), and when an object passes near the light emitter 51. There is a problem that may not be detected. This is because the individual lights emitted from the projector 51 are not actually beam-shaped but spread at a slight angle. That is, considering a certain light receiving element, even if the light from the light emitting element facing it is blocked, the light of the light emitting element in the vicinity thereof enters the above light receiving element. In this way, the amount of light entering from the light emitting elements in the vicinity increases as the object moves away from the light receiver 52, and when the amount of the light exceeds the threshold value for detecting that the light is blocked, it is possible to catch the passage of the object. Can not. Therefore, for example, when it is used to measure the number of passing objects 53, a counting error occurs.

The present invention has been made in order to solve the above problems, and has a wide field of view capable of detecting an object with substantially uniform sensitivity within a predetermined range regardless of the passing position of the object. An object is to provide a photoelectric detection device.

[0005]

According to the present invention, there is provided a light emitter / receiver for a wide-field photoelectric detection device, wherein a plurality of light emitting elements which are arranged in a line and are driven at the same time and the light emitting elements are alternately arranged.
And, the same number of light receiving elements arranged in the same row, and an OR circuit for taking the logical sum of all the outputs of the above light receiving elements and outputting the result.
And a case for accommodating the above-mentioned respective parts. Further, the wide-field photoelectric detection device according to the present invention has a plurality of light emitting elements which are arranged in a row and should be driven simultaneously, and light receiving elements which are arranged alternately with the light emitting elements in the same number. The first light emitter / receiver has the same structure as the first light emitter / receiver, and the light emitting element and the light receiver element are rotated by 180 ° on the same plane with respect to the first light emitter / receiver. A second light emitter / receiver arranged to face the light receiving element and the light emitting element of the first light emitter / receiver facing each other so that their optical axes coincide with each other; a light emitting element of the first light emitter / receiver; Light emitting element driving means for alternately supplying a pulse to the light emitting element of the light emitting and receiving element of the light emitting and receiving element, and a light-shielding output signal of the light receiving element of the light emitting and receiving element facing the light emitting and receiving element to which the pulse is supplied by the light emitting element driving means. Light-shielding detection means for detecting
Output means for outputting the light-shielding time output signal detected by the light-shielding detection means in the form of a pulse having a predetermined waveform. A first light emitter / receiver having a plurality of light emitting elements which are arranged in a line and are to be driven simultaneously, and light receiving elements which are arranged in the same number alternately and in the same number as the light emitting elements; The light emitting element and the light receiving element are arranged to face the light receiving element and the light emitting element of the first light emitting and receiving device so that their optical axes coincide with each other. A second projecting / receiving device that forms a detection surface region through which the object to be detected should pass, and a pulse to be supplied are changed at least once while the object to be detected passes through the detection surface region. A first pulse train and a second pulse train that are in a relationship that alternately generate pulses at a speed that allows
Pulse trains of the first and second light emitters / receivers
Light emitting element driving means for supplying to the light emitting and receiving device, and light shielding detecting means for detecting a light shielding output signal of the light receiving element of the light emitting and receiving device facing the light emitting and receiving device to which the pulse is supplied by the light emitting element driving means, It is also possible to provide a wide-field photoelectric detection device provided with an output unit that outputs the light-shielding time output signal detected by the light-shielding detection unit as a pulse having a predetermined waveform.

[0006]

According to the projector and receiver for a wide-field photoelectric detection device according to the present invention, a pair of light emitting elements and a light receiving element provided inside thereof are arranged so as to face each other. A positional relationship is established between the light receiving element and the light emitting element of the light receiver so that they can project and receive light. The light-emitting element driving means in the wide-field photoelectric detection device according to the present invention supplies a pulse for causing the light-emitting elements of the pair of light-emitters and light-receivers arranged facing each other to emit light alternately. The light-shielding detection means detects the light-shielding output signal on the light receiving side,
The output means outputs this as a pulse having a predetermined waveform.

[0007]

1 is a cross-sectional view of a light emitter / receiver 1 of a wide-field photoelectric detection device according to an embodiment of the present invention. In the figure, a light emitter / receiver 1 includes a plurality of (nine in this embodiment) light emitting elements 2 in a case 1a having a mounting hole 1b, the same number of light receiving elements 3 and other electronic components (not shown). have.
The light emitting element 2 and the light receiving element 3 emit and receive infrared light, respectively, and are arranged linearly and alternately. An infrared filter 4 is provided on the front surface of the light emitting element 2 and the light receiving element 3 to minimize disturbance due to visible light. Fig. 5 shows a pair of the light emitter / receiver 1 as described above (one for 1L and the other for 1R), one on the same plane.
When rotated 180 °, the light emitting element 2 (FIG. 1) and the light receiving element 3 (FIG. 1) of the light emitter / receiver 1L face the light receiving element 3 and the light emitting element 2 of the light emitter / receiver 1R, respectively, and their optical axes coincide with each other. FIG. 3 is a perspective view showing a state in which they are arranged so as to face each other. A detection area B is formed by the arrangement of the light emitting elements 2 and the light receiving elements 3 in the light emitters / receivers 1L and 1R, and the detection is performed by blocking the light A by the object 53 passing therethrough.

Next, the internal circuit of the light emitter / receiver 1 (1L, 1R) will be described. FIG. 2 is an internal circuit diagram of the projector / receiver 1. External connection terminals are power supply terminal Vcc, common side terminal GND,
Input terminal IN and output terminal OUT. 9 for input terminal IN
One end of the series connection body of the individual light emitting elements 2 is connected, and the resistor 5 is connected to the other end. Light emitting element 2 is an input terminal
It emits light only when a specified voltage (24V) is applied to IN.
The output terminal of the OR circuit 7 is connected to the output terminal OUT. The OR circuit 7 has eight inputs, and further has nine inputs in total by amplifying the number of inputs by the OR circuit 8. A predetermined voltage (5 V) is constantly applied to the nine light receiving elements 3 separately via the resistor 6, and each collector is connected to the input terminal of the OR circuit 7 or 8. Light receiving element 3
Is conductive when receiving light, and its collector voltage is at L level, but when light is blocked, it becomes non-conductive and the collector voltage changes to H level. Since the OR voltage of the collector voltages of all the light receiving elements 3 is taken, the output of the OR circuit 7 becomes H level if there is even one light receiving element 3 shielded from light.

Next, the control of the light emitter / receiver 1 (1L, 1R) will be described. Fig. 3 is a control unit for the projectors 1L and 1R
3 is a circuit diagram showing a state in which the counter 32 is connected to the control unit 10 and the counter 32 is connected to the control unit 10. FIG. In the figure, the control unit 10 has 24 V from an external DC power source 31 via terminals T1 and T2.
The constant voltage circuit that supplies the DC voltage of 5V and supplies the DC voltage to each part in the unit as it is and also reduces it to 5V.
It also has 11. The power of 5V is also supplied to the light emitters / receivers 1L and 1R through the terminals T3 and T4. As shown in FIG. 4, the pulse generation circuit 13 outputs two sets of pulse trains P1 and P2 having the same cycle and a timing shifted by a half cycle, and alternately turns on the transistors 12 and 14 via the transistors 29 and 30, respectively. Turn off. When the transistor 12 is turned on, all the light emitting elements 2 (FIGS. 1 and 2) of the light emitter / receiver 1L emit light simultaneously. When the transistor 14 is turned on, all the light emitting elements 2 (FIGS. 1 and 2) of the light emitter / receiver 1R emit light simultaneously. Thus, the light emitters / receivers 1L and 1R alternately emit light according to the pulse train output from the pulse generation circuit 13.
The voltage applied to the collector of the transistor 12 or 14 at the time of light projection is stepped down to a predetermined voltage (5 V) by the constant voltage circuit including the resistor 15 and the Zener diode 16 or the constant voltage circuit including the resistor 17 and the Zener diode 18 and the AND circuit. 19
Alternatively, it is supplied to one of the 20 input terminals.

Now, assuming that the transistor 14 is off and the transistor 12 is on, the light emitted from the light emitter / receiver 1L is reflected by the light receiving element 3 (FIG. 1 or 2) of the light emitter / receiver 1R. Received light. As described above, when all the light receiving elements 3 (FIG. 2) are in the light receiving state, the output of the OR circuit 7 (FIG. 2) is at L level, and one input of the AND circuit 19 is at L level. At this time, the other input of the AND circuit 19 is at the H level because the transistor 12 is on. Therefore, the output of the AND circuit 19 is at L level. On the other hand, in the AND circuit 20, one input is always at the L level because the transistor 14 is in the OFF state, and therefore the output is at the L level regardless of the other input level. Since the outputs of the AND circuits 19 and 20 are both at the L level, the OR circuit 21 and the inverter
An H level signal is input to the output pulse guarantee circuit 23 via 22. At this time, the output pulse guarantee circuit 23 does not drive the transistor 24 connected to its output side. Therefore, the photocoupler 26 connected to the collector of the transistor 24 does not operate, and the operation display LED 28 does not light up.

If the transistor 14 is off and the transistor 12 is on, the light emitting / receiving device on the light receiving side
When the light reception to at least one light receiving element 3 (FIG. 2) of 1R is blocked by the passage of the object 53 (FIG. 5), the OR circuit 7
The output of (FIG. 2) becomes H level. Therefore, one input to the AND circuit 19 becomes H level via the terminal T7, and at that time, the other input of the AND circuit 19 is supplied with an H level input by turning on the transistor 12. As a result,
The AND circuit 19 outputs the H level and the AND circuit 20 outputs the L level, and the L level signal is input to the output pulse guarantee circuit 23 via the OR circuit 21 and the inverter 22. In response to this, the output pulse guarantee circuit 23 drives the transistor 24, operates the photocoupler 26, and turns on the LED 28. The operation of the photocoupler 26 drives the counter 32. Note that the signal output from the light emitter / receiver 1R is a pulse-shaped signal output only at the moment when the object 53 (FIG. 5) passes between the light emitter / receiver 1L and 1R, but in reality it is a single rectangle. It is not limited to a wave, but is often a collection of two or more short pulse signals. Therefore, even though one object 53 (FIG. 5) has passed, a signal as if two or more objects passed may be output from the light emitter / receiver 1R. The output pulse guarantee circuit 23 accepts only the first input pulse so as not to generate a counting error even in such a case, and immediately after that, ignores the subsequent signal and outputs the single pulse necessary for the operation of the counter 32. One predetermined length (eg 30m / sec)
It is configured to output a pulse of. Therefore, the counter 32 operates accurately and surely. On the other hand, when the transistor 14 is on and the transistor 12 is off, the positions of the light emitters / receivers 1L and 1R are switched and the same operation is performed. That is, since one input terminal of the AND circuit 19 is kept at the L level by turning off the transistor 12, the output is L regardless of the input to the other input terminal.
It is a level. When one of the input terminals of the AND circuit 20 is turned on, a high level signal is constantly given to it by turning on the transistor 14.
When passing through the object 53 (FIG. 5), an H level signal is applied from the output terminal OUT of the light emitter / receiver 1L to the other input terminal of the AND circuit 20. Thus, the AND circuit 20 outputs the H level signal. The subsequent operation is exactly the same as the above case.

FIGS. 6 to 8 are schematic diagrams showing how a wide-field photoelectric detector constructed as above detects a passing object. In FIG. 6, S1 to S9 are light emitting elements, and R1
Reference characters R9 to R9 denote light receiving elements, in which the light emitting element on the left side is projecting light. In this state,
When the object 53 passes through the position shown in the figure perpendicularly to the paper surface,
When viewed from the light receiving element R5 on the right side, the range indicated by the diagonal lines in the figure becomes a blind spot due to the existence of the object 53. Therefore, not only the light from the light emitting element S5 but also the light emitting element S in the vicinity thereof
Light from 4 and S6 does not enter the light receiving element R5.
Therefore, the light shielding in the light receiving element R5 is surely performed. Similarly, when the light emitting element on the left side is projecting light, as shown in FIG. 7, when the object 53 tries to pass immediately in front of the light emitting element S5 which is projecting light,
The blind spot seen from the light receiving element R5 becomes a narrow range shown by the shaded area in the figure, and the light from the light emitting element S5 is blocked, but the light from the light emitting elements S4, S6 and the like in the vicinity thereof is not blocked. Therefore, the light from the light emitting elements S4 and S6 may enter the light receiving element R5 and the light blocking may not be established. However, even in such a case, at the next moment, as shown in FIG. 8, the light emitting sides are switched and the light emitting elements S1 to S9 on the right side project light, so that the light receiving elements R5 and R6 on the left side can see. For example, due to the existence of the object 53, the shaded area becomes the blind spot.
Therefore, not only the light emitting elements S5 and S4 on the right side facing the light receiving elements R5 and R6, respectively, but also the light from the light emitting elements S6 and S3 in the vicinity thereof are received on the left side light receiving element R5.
And it will not reach R6. Thus, the light receiving element R on the left side
Shading is established at 5 and R6. Thus, the object
Even when 53 passes immediately before the light-projecting side, which is difficult to detect, the light-projecting side is switched during the passage so that the light can be surely shielded.

Next, the relationship between the passing speed of the object 53 (FIG. 5) and the pulse generated by the pulse generating circuit 13 will be described. For completely accurate detection, the object 53 must be
The time for blocking the optical path between 1L and 1R is the time T shown in FIG.
It needs to be slightly longer. As described above as a problem of the prior art, when the object 53 (FIG. 5) passes immediately in front of the light emitting / receiving device 1L or 1R that is projecting light, it may not be possible to reliably block light. However, even in such a case, the light-projecting side is changed to surely shield the light. Specifically, for example, the pulse frequency is about 1
In the case of kHz, an object of a predetermined size can be reliably detected even at a passing speed of about 20 m / sec. The detection sensitivity regarding the size of the object is determined by the arrangement density of the light emitting elements 2 and the light receiving elements 3 shown in FIG. 1 in the arrangement direction. In this embodiment, since the total array length of the nine light emitting elements 2 and the light receiving elements 3 shown in FIG. 1 is about 90 mm, the arrangement density of each of the light emitting elements 2 or the light receiving elements 3 is about (1/10 mm. ),
If the light emitting element 2 and the light receiving element 3 are not distinguished, the arrangement density is about (1/5 mm). This is almost a limit value in view of the widths of the light emitting element 2 and the light receiving element 3. In this case, it was confirmed that an object with a diameter of 5 mm or more could be detected. To further increase the detection sensitivity, for example, the light emitting element 2 and the light receiving element 3 may be arranged three-dimensionally. That is, three-dimensionally on the light emitting elements (or light receiving elements) arranged in a line,
Similarly, if the light receiving elements (or light emitting elements) arranged in a line are arranged in two stages, the arrangement density is doubled, so that the detection sensitivity is improved.

[0014]

As described above, according to the present invention, a pair of light emitters and light receivers, each having the same number of light emitting elements and light receiving elements and alternately arranged in the same row, are arranged to face each other. Since it is possible to build a positional relationship that can be projected and received
Even when an object tries to pass immediately before the light emitter, which is difficult to be detected, it is possible to detect the passage immediately before the light receiver which is easy to detect by changing the light emitting side at a high speed. Therefore, there is an effect that the detection sensitivity in the field of view can be kept substantially uniform regardless of the passing position of the object.

[Brief description of drawings]

FIG. 1 is a sectional view of an emitter / receiver for a wide-field photoelectric detection device according to an embodiment of the present invention.

FIG. 2 is an internal circuit diagram of the emitter / receiver for a wide-field photoelectric detection device shown in FIG.

FIG. 3 is an overall circuit diagram of a wide-field photoelectric detection device in which a control unit and the like are connected to the light-emitter and receiver for the wide-field photoelectric detection device shown in FIGS. 1 and 2.

4 is a pulse generation circuit in the control unit 10 shown in FIG.
Diagram showing the pulse signal waveform output from 13

5 is a perspective view showing a state in which a pair of the emitter and receiver for the wide-field photoelectric detection device shown in FIG. 1 are arranged so as to face each other.

FIG. 6 is a diagram in which the arrangement shown in FIG. 5 is simplified in a plan view (a state in which an object passes through the center).

FIG. 7 is a schematic plan view of the arrangement shown in FIG. 5 (state in which an object is passing on the left side).

FIG. 8 is a diagram in which the arrangement shown in FIG. 5 is simplified in a plan view (a state in which an object is passing on the left side).

FIG. 9 is a perspective view showing a state in which a light emitter and a light receiver for a conventional wide-field photoelectric detection device are opposed to each other.

[Explanation of symbols]

 1 (1L, 1R) Emitter / receiver 2 Light emitting element 3 Light receiving element 7,8 OR circuit 12,14 Transistor 13 Pulse generation circuit 19,20 AND circuit 21 OR circuit 22 Inverter 23 Output pulse guarantee circuit 24 Transistor 26 Photocoupler 29, 30 transistors

Claims (3)

[Claims] 1. A plurality of light emitting elements which are arranged in a row and are to be driven simultaneously, light receiving elements which are arranged alternately with the light emitting elements and the same number of which are arranged in the same row, and logics of all outputs of the light receiving elements. Output the sum
An emitter / receiver for a wide-field photoelectric detection device, comprising an OR circuit and a case accommodating each of the above parts. 2. A first light emitter / receiver having a plurality of light emitting elements which are arranged in a line and are to be simultaneously driven, and light receiving elements which are arranged in the same number alternately with the light emitting elements. The structure is the same as that of the first light-emitter / receiver, and the first light-emitter and the light-receiver are opposed to each other by rotating 180 ° on the same plane with respect to the first light-emitter / receiver. A second light emitter / receiver arranged to face the light receiver element and the light emitter element of the light receiver so that their optical axes coincide with each other; a light emitter element of the first light emitter / receiver; and a light emitter element of the second light emitter / receiver. A light emitting element driving means for alternately supplying a pulse to the light emitting element driving means, and a light shielding detecting means for detecting a light shielding output signal of the light receiving element of the light emitting and receiving element facing the light emitting and receiving element to which the pulse is supplied by the light emitting element driving means When light is detected by the light-shielding detection means Wide viewing photoelectric detection device provided with output means for the force signal to a pulse having a predetermined waveform, a. 3. A first light emitter / receiver having a plurality of light emitting elements which are arranged in a row and are to be driven simultaneously, and light receiving elements which are arranged in the same number alternately with the light emitting elements. The light-emitting element and the light-receiving element have the same structure as the first light-emitter / receiver, and are arranged to face the light-receiving element and the light-emitter element of the first light-emitter / receiver so that their optical axes coincide with each other. A second projecting / receiving device that forms a detection surface region through which the object to be detected should pass between the first projecting and receiving device, and a pulse to be supplied at least while the object to be detected is passing through the detection surface region. A light emitting element driving means for supplying to the first light emitting / receiving device and the second light emitting / receiving device, respectively, a first pulse train and a second pulse train having a relationship of alternately generating pulses at a speed capable of being changed once. , Pulsed by the light emitting element driving means Light-shielding detection means for detecting the light-shielding output signal of the light-receiving element of the light-emitter / receiver facing the supplied light-emitter / receiver, and the light-shielding output signal detected by the light-shielding detection means is output as a pulse having a predetermined waveform. And a wide-field photoelectric detection device comprising: