JP3132871B2 - Beam sensor system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam sensor system and, more particularly, to a beam sensor system in which the power consumption of a projector is reduced.

[0002]

2. Description of the Related Art Conventionally, there is known a beam sensor system in which a projector for projecting an infrared beam and a photodetector for receiving an infrared beam emitted from the projector are opposed to each other. In such a beam sensor system, in order to secure a sufficient sensitivity margin on the light receiver side, the transmitter emits a signal at the light receiver level, that is, the minimum infrared beam amount necessary to warn an intruder of 40.
It is normal to project up to 150 times the amount of light. For example, if the light receiver determines that an intruder is present when the light receiving signal becomes 5 mV or less, and issues an alert, that is, if the alert level is 5 mV, the emitter emits 200 mV to 750 mV in a normal state. The beam amount is such that a light receiving signal of a sufficient level can be obtained. Projecting a very large infrared beam in this way makes it possible to detect an intruder well even if the projected infrared beam is attenuated due to deterioration of the environment against infrared rays due to fog or rain. However, in this case, as shown in FIG. 4, when there is an object 10 such as a wall surface that reflects infrared rays near the caution area of the beam sensor system, there is no fog or rain, and the environment for infrared rays is good. In such a case, the amount of the reflected light 11 from the object 10 is also very strong, and no alarm is issued because the amount of the reflected light 11 is large even if the infrared beam 12 that goes straight from the light emitter T to the light receiver R is blocked by an intruder. Cases arise.

Therefore, in a conventional beam sensor system, a signal processing circuit of a photodetector is provided so that a reflected light 11 from an object 10 can be ignored in FIG. AG in system
Usually, a C circuit is provided.

FIG. 5 is a diagram showing a schematic configuration example of a conventional AGC circuit. After an output signal of a light receiving element 1 composed of a phototransistor or the like is input to an amplifier 2 and amplified, identification of presence or absence of an intruder is performed. The signal is supplied to a signal processing circuit (not shown) and supplied to the AGC circuit 3. The AGC circuit 3 detects a level of an output signal of the amplifier 2 to generate a control signal for gain control, and a delay for delaying the control signal generated by the level detection circuit 4 by a predetermined time. And a circuit 5.
Accordingly, the control signal generated by the level detection circuit 4 is delayed by a predetermined time by the delay circuit 5 and supplied to the amplifier 2, and the gain of the amplifier 2 is controlled.

As a result, the level of the received light signal of the infrared beam that travels straight from the light emitter to the light receiver is always kept constant, and as shown in FIG.
Even if there is one, the signal level of the reflected light 11 can be suppressed by the AGC circuit 3 to a signal level or lower, so that the signal is always generated when the straight-ahead infrared beam 12 is cut off. Become.

The following conditions are required for the response speed of the AGC circuit. Now, assuming that the response speed of the AGC circuit is very fast, the level of the received light signal decreases when the infrared beam is cut off by an intruder, so that the AGC circuit 3 functions to increase the degree of amplification of the amplifier 2. At this time, there is no problem when there is no disturbance such as incidence of the reflected light 11 as shown in FIG. 4 or an infrared beam from another projector, but for example, when there is the reflected light 11 as shown in FIG. In this case, the light receiving signal of the reflected light 11 is immediately amplified by the amplifier 2 and exceeds the alert level, and as a result, a situation occurs in which an intruder is not alerted despite the presence of an intruder.

The delay circuit 5 is provided to adjust the response speed of the AGC circuit.
In general, the control signal is delayed for about 500 msec to 1 sec. This delay time is based on the fact that the time when the intruder crosses the infrared beam with a sneaky foot is about 300 msec, and by providing this delay circuit 5, reflected light as shown in FIG. Even in such a case, an intruder can be reliably detected.
In the case of fog or rain, the infrared light is absorbed and the received light signal level is reduced. However, even in the case of sudden rainfall, it takes about 3 seconds for the received light signal level to drop to 1/3, which was confirmed by measurement results. Therefore, even if the above delay time is provided, the AGC circuit responds well to fog and rain.

[0008]

However, in the conventional beam sensor system, an extremely large amount of infrared beam, which is about 40 to 150 times the alert level, must always be emitted from the projector, so that power consumption is low. There was a problem that was large. This problem is particularly noticeable during a power outage. In other words, the power of the floodlight is usually supplied from a power supply device that is separate from the floodlight, but a backup battery is generally built in in case of a power failure. This is because if it is large, the backup time by the built-in battery is short.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a beam sensor system capable of greatly reducing the power consumption of a projector.

[0010]

In order to achieve the above object, a beam sensor system according to the present invention comprises: a projector having a light emitting element for emitting a warning infrared beam; In a beam sensor system in which a light receiver having a light receiving element for receiving an infrared beam is disposed to face the light receiver, the light receiver further includes a light emitting element for projecting a certain amount of infrared beam, and the light projector further comprises: A light-receiving element for receiving an infrared beam from a light-emitting element that projects a certain amount of infrared beam from the light-receiving device, and a level of a light-receiving signal output from the light-receiving element, and detects a level of the light-receiving signal. And a projection light amount control means for controlling a light emission amount of a light emitting element which emits a warning infrared beam.

[0011]

The light receiver is provided with a light-emitting element for emitting an infrared beam having a constant intensity, in addition to a light-receiving element for receiving a warning infrared beam emitted from the light emitter. In addition to the light emitting element that emits a warning infrared beam, the light emitter receives a light receiving element that receives the infrared beam emitted from the light emitting element of the light receiver, and a light receiving element that responds to the level of a light receiving signal from the light receiving element. And a light emission control means for controlling the light emission amount of the alarm infrared beam. As a result, the intensity of the warning infrared beam received by the light receiver becomes substantially constant irrespective of environmental changes such as fog and rain. Further, since the intensity of the warning infrared beam can be reduced as compared with the related art, power consumption can be reduced.

[0012]

Embodiments will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an embodiment in a case where a beam sensor system according to the present invention is applied to a so-called single beam sensor that performs caution with one infrared beam. In the drawing, reference numeral 20 denotes a light projector; Body-shaped reflecting mirror, 22 is a light-emitting element, 23 is a light-receiving element, 24 is a projection light amount control means, 25 is a light-emitting drive circuit, 30 is a light receiver, 31 is an integrated reflecting mirror, 32
Is a light receiving element, 33 is a light emitting element, 34 is a signal processing means, 3
Reference numeral 5 denotes a light emission drive circuit.

In FIG. 1, a light projector 20 includes a light emitting element 22 for emitting a warning infrared beam 36, and a light receiving element 23 for receiving an infrared beam 37 emitted from a light emitting element 33 of a light receiver 30. ing. The light emitting element 22 and the light receiving element 23 are respectively arranged at the focal positions of separate reflecting mirrors, and these two reflecting mirrors are integrally adjusted in the optical axis direction by a sighting means constituted by a screw or the like. It has been made possible. This is the integrated reflector 21
It is.

The light receiver 30 is arranged to face the light projector 20 and has a light receiving element 32 for receiving a warning infrared beam 36 from the light emitting element 22 of the light projector 20.
And a light emitting element 33 for projecting an infrared beam 37 of a predetermined constant amount toward the light receiving element 23 of the light projector 20. The light receiving element 32 and the light emitting element 33 constitute the integral reflecting mirror 31, respectively. It is arranged at the focal position of the two reflecting mirrors.

The light receiver 30 has a light emission driving circuit 35 for driving the light emitting element 33 and a signal processing means 34 for processing a light receiving signal output from the light receiving element 32 to determine the presence or absence of an intruder. It has. Signal processing means 34
Is similar to the conventional configuration except that the above-mentioned AGC circuit is not provided, and the output signal of the signal processing means 34 is sent to a receiver (not shown). The light emission drive circuit 35 is the same as the light emission drive circuit in the conventional projector, and drives the light emission of the light emitting element 33 by a pulse of a predetermined cycle. It is set to a small value of about 5 to 10 times. Therefore, the power consumption of the light emitting element 33 is very small.

The light projector 20 further includes a light quantity control means 24,
A light emission drive circuit 25 is provided. The projection light amount control unit 24 detects the level of a light reception signal output from the light reception element 23,
The light emission drive circuit 25 is controlled according to the light receiving signal level to control the light emission amount of the light emitting element 22. For example, as shown in FIG. 3, when there is no fog, rain, dust, etc., and the environment for infrared rays is the best,
_{Assuming that} the light emission amount of the light emitting element 22 at this time is L ₀ , the environment deteriorates due to fog or rainfall, and the light emission amount is reduced along the characteristic indicated by 50 as the light reception signal level is reduced. Control to increase. Thus, the light receiver 3
The level of the light receiving signal output from the light receiving element 32 of 0 is always substantially constant. Here, the light emission amount L of the light emitting element 22
₀ is set to about 5 times the alert level of the light receiver 30.
Therefore, the power consumption of the light emitting element 22 is very small as compared with the conventional one.

FIG. 2 shows a more detailed configuration example for controlling the light emission amount of the light emitting element 22 as described above. The projection light amount control means 24 includes a level detection circuit 40 and a delay circuit 41. The level detection circuit 40 converts the AC signal output from the light receiving element 23 into a DC signal and outputs the DC signal, and has the same configuration as the level detection circuit 4 in the conventional AGC circuit shown in FIG. The delay circuit 41 has the same function as the delay circuit 5 in the conventional AGC circuit shown in FIG. 5, and its delay time is set to 500 msec to 1 sec. The output of the delay circuit 41 is input to the variable resistance means 43 of the light emission drive circuit 25. In the figure, the variable resistance means 43 is composed of a transistor. The transistor has its conduction controlled by a DC signal output from the delay circuit 41, whereby the current supplied to the light emitting element 22 composed of a light emitting diode is controlled. Is controlled, and the light emission amount is controlled. In FIG. 2, reference numeral 44 denotes a pulse generator.
The transistor 45 is turned on / off by a pulse output from the pulse generator, and when the transistor 45 is turned on, a current is supplied to the light emitting element 22 to emit light.

Although one embodiment of the present invention has been described above, it is apparent to those skilled in the art that the present invention is not limited to the above-described embodiment, and that various modifications are possible. For example, in the above-described embodiment, the integrated reflector is used. However, it is necessary that the relationship shown in FIG. 3 be maintained between the amount of light received by the light receiving element 23 and the amount of light emitted by the light emitting element 22. Therefore, it is necessary that the light emitting element 22 and the light receiving element 23 face in the same direction, and this is because the condition can be easily satisfied by using an integrated reflector. It is not necessary to be an integral type as long as the conditions described above can be satisfied.

The configuration of the variable resistance means 43 is not limited to that for controlling the degree of conduction of the transistor, but may be any circuit capable of controlling the current flowing through the light emitting element. Further, the relationship between the light receiving signal level of the light receiving element of the light projector and the light emission amount of the light emitting element is 50 in FIG.
The curve is not limited to a curve as shown in the figure, but may be linear, or may be step-like. In short, any characteristic may be used as long as the amount of light emission increases when the light reception signal level decreases. Things.

[0020]

As is apparent from the above description, according to the present invention, the power consumption of the light emitting element of the light projector can be significantly reduced as compared with the conventional one, and thereby the backup time at the time of a power failure due to the battery can be reduced. It can be greatly improved. In the case where the light emission amount of the light emitting element of the light projector is controlled by controlling the current flowing through the light emitting element,
Since a large dynamic range can be obtained, the present invention can be applied to a beam sensor system installed in any environment. Further, in the above embodiment, a single beam sensor is described as an example. However, the present invention can be applied to a multi-beam sensor that performs alarm using a plurality of infrared beams.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment when the present invention is applied to a single beam sensor.

FIG. 2 is a diagram illustrating an example of a circuit configuration for controlling a light emission amount.

FIG. 3 is a diagram illustrating light emission amount control according to the present invention.

FIG. 4 is a diagram for explaining the necessity of an AGC circuit.

FIG. 5 is a diagram illustrating a schematic configuration example of a conventional AGC circuit.

[Explanation of symbols]

20: floodlight, 21: integrated reflector, 22: light emitting element,
Reference numeral 23: light receiving element, 24: projection light amount control means, 25: light emission drive circuit, 30: light receiver, 31: integrated reflector, 32: light receiving element, 33: light emitting element, 34: signal processing means, 35 ...
Light emission drive circuit.

Claims (1)

(57) [Claims] 1. A beam in which a light emitter having a light emitting element for emitting a warning infrared beam and a light receiver having a light receiving element for receiving a warning infrared beam from the light emitting element of the light emitter are opposed to each other. In the sensor system, the light receiver further includes a light emitting element that emits a certain amount of infrared beam, and the light emitter further receives an infrared beam from the light emitting element that emits a certain amount of infrared beam of the light receiver Light-receiving element for detecting the level of a light-receiving signal output from the light-receiving element, and controlling the light-emitting amount of a light-emitting element that emits a warning infrared beam according to the level of the light-receiving signal A beam sensor system comprising a control unit.