JPH0412837B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> This invention is aimed at detecting the difference between the amount of infrared energy emitted from an object such as a moving human body and the amount of infrared energy emitted from the background such as the floor of a building. This invention relates to an infrared moving object detection device that detects objects and controls the opening and closing of automatic doors and the operation of security alarm systems.

<Conventional technology> All objects above absolute zero (-273°C) emit infrared rays corresponding to their temperature, but human bodies and buildings at room temperature emit far infrared rays with a wavelength of around 10 μm. There is. An infrared moving object detection device sets a predetermined detection area on the floor of a building, etc., and constantly monitors infrared rays emitted from this detection area using an optical system. It is configured to detect changes in the amount of infrared energy caused by the intrusion of an object such as a human body into the detection area, and issue an opening signal for an automatic door or a signal for a security alarm system. be.

Incidentally, recently, chemically treated cloth dust absorbing mats have been increasingly installed in front of automatic doors. The cloth material of this dust-absorbing pine has a small heat capacity and has long piles, so it is susceptible to sudden temperature changes due to direct sunlight or the slowness and speed of wind.
For this reason, a detection area is set outdoors, especially when exposed to direct sunlight, and under conditions where the temperature of the dust suction mat installed within this detection area differs from the ambient temperature, the temperature of this dust suction mat may be affected by wind, etc. When the temperature changes, the amount of infrared energy incident on the infrared detection element changes, so the infrared moving object detection device detects the temperature change of the dust suction mat itself and automatically opens or closes it even though there is no movement of the dust suction mat within the detection area. A malfunction occurs when the door is activated. If the detection sensitivity is lowered to prevent this malfunction, as shown in FIGS. 9 and 10, the frequency of malfunctions will be reduced by not reacting as sensitively to temperature changes. When the temperature difference between the internal temperature and the temperature of a moving object such as a human body to be detected becomes small, detection becomes impossible and the frequency of failure to detect increases. In order to prevent this, if the detection sensitivity is increased to give priority to the detection ability, there is a contradiction in that the frequency of the above-mentioned malfunctions will increase.

Therefore, in order to solve these problems, the applicant has devised an infrared moving object detection device equipped with an automatic gain adjustment circuit (Japanese Patent Application Laid-Open No. 1983-1993).
No. 60587). This device is suitable for use when there is a large temperature change within the detection area, the temperature difference between the detection area temperature and the ambient temperature is large as shown in Figure 5, and the human body to be detected is detected as shown in Figure 4. This was done by focusing on the following conditions: the temperature difference between the background detection area and the detection area is significantly large compared to the detection sensitivity, and the temperature change within the detection area occurs continuously, unlike when a human body moves. The system detects noise caused by temperature changes in the detection area, and uses an automatic gain adjustment circuit to lower the detection sensitivity depending on the level of this noise, or lowers the level of the signal itself, so that the signal remains unchanged regardless of the magnitude of the temperature change. The level and detection sensitivity are kept relatively constant.

<Problems to be Solved by the Invention> However, when a moving object continuously passes through the detection area or stops within the detection area and moves slightly, the detection signal of this object is This signal is similar to a noise signal due to temperature changes, which malfunctions and reduces detection sensitivity, so there is a drawback that moving objects cannot be detected reliably. Therefore, the same applicant as the present application corrected the detection sensitivity using a sensitivity correction circuit in response to fluctuations in the noise signal caused by temperature changes in the detection area, and suspended sensitivity correction when the object moved into the detection area. He has already devised and filed an application for an infrared moving object detection device in which the function of the sensitivity correction circuit is temporarily interrupted by a circuit (Japanese Patent Laid-Open No. 60-230081). Although this device can eliminate the above-mentioned drawbacks by using a sensitivity correction interruption circuit, time delays and damped vibrations that occur in the circuit system after the signal input is no longer detected may be detected as noise due to external disturbances. The slight drawback is that the tolerance range for determining the value is small.

In addition, even if the temperature in the detection area is different from the ambient temperature and is likely to change, but there is no wind etc. and it is not detected as a noise signal, for example, if a gust of wind blows and temperature fluctuation occurs, the detection Since the sensitivity has not decreased, a malfunction occurs in detecting the temperature change caused by this gust of wind. If the response speed is increased to the extent that it can cope with such a situation, it becomes impossible to detect even the most important moving object.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and is capable of preventing malfunctions due to temperature changes due to gusts of wind, etc. under conditions where the temperature within the detection area is different from the surrounding temperature. To reliably detect a moving object even when the temperature difference between the temperature within the detection area and the temperature of the moving object such as a human body to be detected is small, or when the moving object continuously passes through the detection area. The object of the present invention is to provide an infrared moving object detection device that can perform the following steps.

<Means for Solving the Problems> In order to achieve the above object, the infrared moving object detection device of the present invention includes an optical system that condenses an infrared beam emitted from a predetermined detection area, and an infrared light beam. an infrared detection element consisting of a photoconductive effect type infrared light sensor or a thermal type light sensor that converts the thermal radiation energy incident from the optical system into an electrical signal according to the amount of variation thereof, with the measurement wavelength being the measurement wavelength; An amplifier circuit that amplifies an electrical signal, an infrared level detection circuit that outputs a trigger signal when the amplified signal of this amplifier circuit exceeds a predetermined level, and an automatic door opening/closing circuit that receives the trigger signal from this infrared level detection circuit. In an infrared moving object detection device equipped with an output circuit that outputs an activation signal to control the The illuminance detection circuit includes an illuminance detection element that outputs an electric signal proportional to the density of the luminous flux, and an illuminance detection circuit that outputs a detection signal according to the amount of variation in the output of the illuminance detection element, and the output detection signal of the illumination detection circuit. an illumination level detection circuit that outputs a trigger signal when a predetermined level is exceeded; and a gate that outputs a signal to the output circuit only when a trigger signal is output from both the illuminance level detection circuit and the infrared level detection circuit. The gist is a configuration comprising a circuit.

<Function> With the above configuration, from the illumination detection element arranged facing the detection area separately from the infrared detection element, the luminous flux per unit area incident on the surface facing the detection area is proportional to the luminous flux per unit area. An electric signal, that is, an electric signal proportional to the illuminance around the illuminance detection element is output, and a detection signal corresponding to the amount of variation in this electric signal is output from the illuminance detection circuit. Therefore,
The detection signal output from the illuminance detection circuit corresponds to the illuminance of the detection area due to direct sunlight or the like. If a moving object enters the detection area,
Since the detection area and the moving object have different reflectances or reflection positions for sunlight, the illuminance changes, and the moving object can be detected by detecting the amount of variation in the illuminance. Therefore, the infrared level detection circuit not only detects fluctuations in infrared energy exceeding a predetermined value to obtain a detection signal of a moving object, but also uses the illuminance level detection circuit to detect fluctuations in the output detection signal of the illuminance detection circuit over a predetermined value. Since the output circuit is driven only when both detection signals are generated, malfunctions and undetectable states do not occur.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing one embodiment, an infrared light beam emitted from a predetermined detection area is condensed by an optical system 1 and enters an infrared detection element 2. In FIG. The infrared detection element 2 consists of a thermal type optical sensor such as a pyroelectric detector, a thermistor bolometer, or a thermoelectric pile, or a photoconductive effect type infrared optical sensor, and measures the amount of variation in incident thermal radiation energy using infrared light as the measurement wavelength. Convert it into an electrical signal according to the The amplified signal amplified by the amplifier circuit 3 is detected by the infrared level detection circuit 4, which detects the signal strength,
That is, the amount of variation in the infrared light flux is monitored, and when the infrared level detection circuit 4 detects a variation exceeding a predetermined detection sensitivity, it outputs a trigger signal having a predetermined time length. The output circuit 5 is activated by the trigger signal of the infrared level detection circuit 4 and outputs an activation signal to the controller 6, and the controller 6 outputs an automatic door opening signal and the like.

The present invention is characterized in that the following configuration is added to the infrared moving object detection device having the basic configuration as described above. That is, a condensing system 7 that condenses the incident luminous flux from the detection area, and a phototransistor, photodiode, solar cell, etc. that outputs an electric signal proportional to the luminous flux per unit area incident from the concentrating system 7. An illuminance detection circuit 8 that includes an illuminance detection element consisting of an electromotive force effect type optical sensor or a photoconductive effect type visible light sensor such as a CdS cell, and outputs a detection signal according to the amount of variation in the output electric signal of this irradiation detection element.
, an amplifier circuit 9 that amplifies the illuminance detection signal of this illuminance detection circuit 8, an illuminance level detection circuit 10 that outputs a trigger signal when the amplified signal of this amplifier circuit 9 exceeds a predetermined level, and this illuminance level detection An AND gate circuit 11 that outputs a signal to the output circuit 5 only when a trigger signal is output from the circuit 10 and the infrared level detection circuit 4, respectively, and the illuminance detection circuit 8.
an illuminance absolute value detection circuit that detects the absolute value of illuminance around the illuminance detection element in the illuminance detection circuit 8 arranged toward the detection area by integrating the output of 1
2, a switch 13 which is commonly connected to the input terminal of the AND gate circuit 11 together with the illumination level detection circuit 10 and is closed by driving the illuminance absolute value detection circuit 12; and a switch 13 which is connected to this switch 13 via a load resistor 15. The configuration is such that a DC power supply 14 is added.

Next, to explain the operation of the embodiment device configured as described above, when a moving object enters the detection area in a state of high illuminance that causes a temperature change within the detection area, the background that becomes the detection area The illuminance changes because the reflectance or reflection position of the moving object for sunlight differs. Therefore,
The trigger signal output when the amount of change in illuminance exceeds the detection reference level of the illuminance level detection circuit 10 becomes a detection signal of a moving object. However, when there is no direct sunlight or when the illuminance is low, such as at night, the change in illuminance due to a moving object becomes small, making it impossible to detect the moving object. In other words, when detecting a moving object only by changes in illuminance, the frequency of undetectable objects is
As shown by the broken line in the figure, it is approximately inversely proportional to the illuminance. On the other hand, the frequency of malfunctions by the infrared level detection circuit 4, which outputs a trigger signal when a moving object is detected due to a change in the amount of infrared energy, is
The illumination intensity increases as the illuminance increases, as shown by the curve shown by the dashed line in the figure. Therefore, the illuminance level indicated by A in FIG. If the value is below, the illuminance absolute value detection circuit 12 is driven and the switch 13 is closed, and the power supply voltage of the DC power supply 14 is applied to one input terminal of the AND gate circuit 11 via this switch 13. There is. Therefore, the signal input to the output circuit 5 is determined by the trigger signal of the infrared level detection circuit 4. That is, in the range of illuminance indicated by B in FIG. 2, where the object becomes undetectable with high frequency, a moving object is detected only by a change in the amount of infrared energy. By the way, as is clear from Figures 3 to 5, illuminance is proportional to the temperature difference between the ambient temperature and the detection area, the temperature difference between the human body and the detection area, and the temperature change in the detection area. When the illuminance is low, the temperature change in the detection area is also extremely small, so even if a moving object is detected only by a change in the amount of infrared energy, the frequency of malfunctions is extremely low, as shown by the solid line in FIG.

On the other hand, in the illuminance range shown by C in the figure where the illuminance level is higher than the level shown by A, the absolute value of illuminance detection circuit 12 is not driven, so the switch 13 is not activated.
is in an open state, and the AND gate circuit 11 outputs a signal to the output circuit 5 only when a trigger signal is output from the infrared level detection circuit 4 and the illuminance level detection circuit 10, respectively. Therefore,
For example, in a state where the temperature of the detection area or the temperature difference between the ambient temperature and the temperature of the detection area is large, a gust of wind or the like causes a change in the amount of infrared energy due to an instantaneous temperature change, and this causes the infrared level to be detected. Even if the trigger signal is output from the circuit 4, since the illuminance remains unchanged, the illuminance level detection circuit 10 will not output a trigger signal, and as a result, no malfunction will occur. In addition, the illuminance absolute value detection circuit 12 has a circuit configuration that integrates with a large time constant, and performs sampling over a relatively long period of time. It has become unresponsive to change. Therefore, in the operating region of the illuminance range indicated by C in FIG. 2, the frequency of malfunctions and failure to detect is extremely low, as shown by the solid line in the figure.

In addition, as shown by the two-dot chain line in FIG. 1, either the amplification degree of the amplification circuit 3 or the detection reference level of the infrared level detection circuit 4 is selected depending on the amplification signal of the amplification circuit 9 that amplifies the illuminance detection signal. Alternatively, if both are made variable, and the detection sensitivity of the amount of infrared energy is varied according to the illuminance as shown in Fig. 6, for example, when the detection sensitivity is reduced due to a rise in the temperature of the detection area, If a moving object passes through the detection area continuously, or stops within the detection area and moves slightly, the illuminance will decrease due to differences in the reflectivity or position of reflection of sunlight between the detection area and the moving object. Therefore, moving objects can be reliably detected without deterioration of detection sensitivity.

In addition, detection sensitivity decreases when the illuminance increases and the temperature in the detection area and the temperature difference between the ambient temperature and the temperature in the detection area increases. No malfunction occurs in detecting changes in the amount of energy.

In addition, as shown by the dashed line in FIG. 1, the amplifier circuit 3 is
The frequency characteristics of either or both of the level detection circuit 4 and the level detection circuit 4 may be varied.
That is, the frequency component of the noise signal due to the disturbance shown by the solid curve in FIG. 7 is in a lower frequency band than the frequency component of the detection signal of a moving object such as a human body shown by the broken line in the same figure. Therefore, for example, the amplifier circuit 3 which normally has the amplification degree in the frequency band shown by the dashed line curve in FIG. The degree of amplification in the low range is lowered to lower the detection sensitivity. As a result, even in a state where there is disturbance noise, the detection signal of a moving object is amplified with a large degree of amplification. In this case, unlike conventional devices that vary the detection sensitivity using noise signals, the detection sensitivity is varied by reducing the gain in the low frequency band depending on the illuminance within the detection area, which eliminates the problems of conventional devices. can be resolved.

<Effects of the Invention> As explained above, according to the infrared moving object detection device of the present invention, moving objects can be detected based on changes in the amount of infrared energy and changes in illuminance, and the frequency at which moving objects cannot be detected due to changes in illuminance can be reduced. In the low illuminance range where the detection area is high, the system detects moving objects based only on changes in the amount of infrared energy, so it will not malfunction even under conditions of extreme temperature changes, such as instantaneous temperature changes in the detection area. Therefore, it is possible to provide a perfect infrared moving object detection device that can reliably detect a moving object under any conditions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the infrared moving object detection device of the present invention, and FIG. 2 is a relationship diagram between the detection illuminance shown in FIG. 1 and the frequency of malfunctions and failure to detect.
Figure 3 is a diagram of the relationship between illuminance and the temperature difference between the ambient temperature and the temperature of the detection area, and Figure 4 is a diagram of the relationship between the temperature difference between the ambient temperature and the temperature of the detection area and the temperature difference between the human body and the detection area. , Figure 5 is a diagram of the relationship between the temperature difference between the ambient temperature and the detection area temperature and the temperature change in the detection area, and Figure 6 shows the illuminance and detection sensitivity when the detection sensitivity is variable controlled by the detection illuminance in Figure 1. Fig. 7 is an explanatory diagram of each frequency component of the noise signal and the detection signal of a moving object, and Fig. 8 shows the frequency and amplification when the frequency characteristics of the amplifier circuit are varied by the detected illuminance signal in Fig. 1. FIGS. 9 and 10 are frequency characteristic diagrams showing the relationship with the amplification degree of the circuit, and are explanatory diagrams of the frequency of failure to detect and the frequency of malfunction, respectively, with respect to detection sensitivity in a conventional device. 1...Optical system, 2...Infrared detection element, 3...
Amplification circuit, 4... Infrared level detection circuit, 5...
Output circuit, 6...Controller, 8...Illuminance detection circuit,
10... Illuminance level detection circuit, 11... Gate circuit, 12... Illuminance absolute value detection circuit, 13... Switch, 14... DC power supply.

Claims (1)

[Scope of Claims] 1. An optical system that condenses infrared light flux emitted from a predetermined detection area, and an electric signal that uses infrared light as a measurement wavelength to generate thermal radiation energy incident from the optical system according to the amount of variation thereof. an infrared detection element consisting of a photoconductive effect infrared light sensor or a thermal light sensor that converts into In an infrared moving object detection device comprising an infrared level detection circuit that outputs a trigger signal at certain times, and an output circuit that receives the trigger signal from the infrared level detection circuit and outputs an operating signal to control the opening and closing of an automatic door, etc. , which is a photovoltaic effect type optical sensor or a photoconductive effect type visible light sensor, and includes an illuminance detection element that outputs an electric signal proportional to the density of the luminous flux incident on the surface opposite to the detection area, and this illuminance detection element. An illuminance detection circuit that outputs a detection signal according to the amount of variation in the output of the element, an illuminance level detection circuit that outputs a trigger signal when the output detection signal of this illuminance detection circuit exceeds a predetermined level, and this illuminance level detection circuit. An infrared moving object detection device comprising: a gate circuit that outputs a signal to the output circuit only when a trigger signal is output from both the circuit and the infrared level detection circuit. 2. A DC power supply is commonly connected to one input terminal of the gate circuit together with the illuminance level detection circuit through a normally open switch, and the switch is connected to an illuminance absolute value that detects the absolute value of illuminance from the output of the illuminance detection circuit. An infrared moving object inspection device according to claim 1, characterized in that opening and closing are controlled by a value detection circuit. 3. Claim 1 or 2, characterized in that the gate circuit is an AND gate circuit.
The infrared moving object detection device described in . 4. At least one of the amplification degree of the amplifier circuit, the detection reference level of the infrared level detection circuit, or the frequency characteristics of the amplifier circuit or the infrared level detection circuit is varied by the output of the illuminance detection circuit or the illuminance level detection circuit. An infrared moving object detection device according to any one of claims 1 to 3, characterized in that: