JPH0327079B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is designed to detect 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 detection area. This invention relates to an infrared moving object detection device that detects the presence or absence of a moving object within a detection area based on the difference, and controls the opening and closing of automatic doors and the operation of a security alarm system.

<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. Infrared moving object detection equipment sets a predetermined detection area on the floor of a building, etc., and constantly monitors the infrared rays emitted from this detection area using an optical system. When a human body moves, the amount of infrared energy that enters the infrared detection element changes by the difference between the amount emitted by the human body and the amount emitted by the floor, etc., so the movement of the human body, etc. is detected from the change in the amount of infrared energy. The device is configured to issue an automatic door opening signal, etc.

Incidentally, in recent years, chemically treated cloth dust-absorbing mats have been increasingly installed in front of automatic doors, but the cloth material of these dust-absorbing mats has a small heat capacity and has long piles. , prone to sudden temperature changes due to direct sunlight and slow and fast winds. For this reason, if a detection area is set outdoors that is particularly exposed to direct sunlight, and a dust suction mat is installed in this detection area, an infrared moving object detection device will detect dust that is picked up due to direct sunlight or the slowness of the wind. A sudden temperature change in the mat itself was detected, causing malfunctions such as automatic doors operating even though there were no moving objects within the detection area.

Therefore, the applicant has proposed that the erroneous output of the object detection signal caused by the dust suction mat occurs only when the background temperature changes rapidly and the temperature difference between the human body and the background is significantly large compared to the detection sensitivity of the detection device. Detection sensitivity automatic correction focuses on the occurrence of the signal and corrects the detection sensitivity by lowering the detection level depending on the degree of change when the background temperature changes significantly, or by lowering the level of the signal itself. He has devised and applied for an infrared moving object detection device that is equipped with a circuit to prevent malfunctions by keeping the signal level and detection sensitivity relatively constant regardless of the magnitude of background temperature changes. There is. (Akira Jitsuka
59-60587) <Problems to be Solved by the Invention> This infrared moving object detection device lowers the detection level or signal level accordingly to reduce noise when the background surface temperature of the detection area fluctuates significantly. In addition to reliably preventing malfunctions caused by
Even if the signal level or detection level is slightly lower, the signal due to the surface temperature difference between the background and the human body is sufficiently large compared to the detection level of the level detection circuit, so moving objects within the detection area can be reliably detected. be able to.

However, there are still problems that must be solved in order to ensure reliable operation under various conditions. In other words, if a human body etc. enters the detection area with sufficient time intervals, there will be no problem, but if a human body etc. enters the detection area continuously, the human body may enter the detection area. The detection sensitivity automatic correction circuit also functions due to changes in the amount of infrared energy caused by the human body entering the detection area, so if a human body subsequently enters the detection area, the detection sensitivity for that human body becomes low. Similarly, if a human body enters the detection area one after another, the detection sensitivity will decrease each time, so even if a human body enters the detection area, it will not be able to be detected, and the automatic door This may cause inconveniences such as not being able to open, or not being able to issue an alarm signal even though there is an illegal trespasser in the guarded area.

The present invention has been made in view of these problems, and is equipped with an automatic detection sensitivity correction circuit to prevent malfunctions due to background temperature changes, while also preventing objects that continuously enter the detection area. A technical object of the present invention is to provide an infrared moving object detection device that can reliably detect moving objects.

<Means for Solving the Problems> In the present invention, as a technical means for achieving the above-mentioned problems, an infrared moving object detection device is configured as follows. That is, an optical system that condenses infrared light flux emitted from a predetermined detection area, an infrared detection element that converts the amount of infrared energy incident through this optical system into an electrical signal proportional to the amount of variation thereof, and an infrared detection element that converts this electrical signal. An amplifier circuit that amplifies, a level detection circuit that outputs an object detection signal when this amplified signal exceeds a predetermined detection level, and a controller that controls the opening and closing of automatic doors etc. is activated by the output of this object detection signal. An infrared moving object comprising: an output circuit that outputs a signal; and an automatic detection sensitivity correction circuit that variably controls the gain of the amplifier circuit or the detection level of the level detection circuit in accordance with fluctuations in the amplified signal level of the amplifier circuit. In the detection device, the sensor is inserted and connected between the output terminal of the level detection circuit and the detection sensitivity automatic correction circuit, and is driven only when the object detection signal is output from the level detection circuit to the detection sensitivity automatic correction circuit. On the other hand, the present invention is characterized in that a sensitivity correction interruption circuit is provided which functions to maintain the output of this circuit at the signal level at the time of output of the object detection signal.

<Function> When the temperature change in the background set as the detection area increases, the amplified signal level of the amplifier circuit also fluctuates accordingly, and the detection sensitivity automatic correction circuit adjusts the gain of the amplifier circuit or the level detection circuit according to this fluctuation. Since the detection level is lowered and the detection sensitivity is lowered, malfunctions due to severe fluctuations in the surface temperature of the dust suction mat installed in the detection area can be prevented. Here, when a human body etc. enters the detection area, the signal due to the difference in surface temperature between the background and the human body will be sufficiently small compared to the detection level of the level detection circuit, even if the gain of the amplifier circuit is slightly smaller. Since it is large, moving objects such as human bodies can be detected reliably.

Then, when a moving object within the detection area is detected and an object detection signal is output from the level detection circuit,
The detection signal drives the sensitivity correction interruption circuit, and short-circuits, for example, required parts of the detection sensitivity automatic correction circuit to ground. As a result, the detection sensitivity automatic correction circuit ceases to function, and its output is held at the signal level at the time when the object detection signal was output, and the detection sensitivity at that time is maintained constant. Here, if a human body continuously enters the detection area, the object detection signal will be output almost continuously during that time, and the detection sensitivity automatic correction circuit will continue to stop functioning, and the detection sensitivity will be maintained constant. Therefore, the human body can be detected reliably.

When the human body stops entering the detection area, the sensitivity correction interruption circuit stops driving when the object detection signal is no longer output, and the detection sensitivity automatic correction circuit starts functioning again, preventing malfunctions caused by noise signals. do.

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

In the diagram showing the block configuration of one embodiment of the present invention, infrared light beams emitted from a predetermined detection area are condensed by an optical system 1 and incident on an infrared detection element 2. The infrared detection element 2 is a pyroelectric detector, a thermistor bolometer, a thermoelectric stack, or the like, and converts the amount of infrared energy incident through the optical system 1 into an electric signal proportional to the amount of variation thereof. This electric signal is amplified by an amplifier circuit 3, and the signal strength of this amplified signal, that is, the amount of variation in infrared light flux, is monitored by a level detection circuit 4. When the level detection circuit 4 detects a variation exceeding a predetermined detection level, It detects that a moving object has entered the detection area and outputs an object detection signal (trigger signal) of a predetermined length of time. The output circuit 5 is driven by this object detection signal and outputs an actuation signal to the controller 6, and the controller 6 outputs an automatic door opening signal and the like.

In the basic configuration of the infrared moving object detection device as described above, an automatic detection sensitivity correction circuit 7, which is an example of a circuit configuration for automatically adjusting the gain of the amplifier circuit 3, is connected to the amplifier circuit 3. A sensitivity correction interrupting circuit 8 is interposed and connected between the output terminal and the detection sensitivity automatic correction circuit 7, and the configuration thereof will be explained together with the following operation explanation.

When the temperature change of the background set as the detection area increases, the amplified signal level of the amplifier circuit 3 increases accordingly, and the output signal level of the amplifier _A2 of the detection sensitivity automatic correction circuit 7 also increases accordingly. When the output signal level of amplifier A ₂ exceeds a predetermined value, transistor Q ₂ becomes conductive and its collector voltage decreases. As this collector voltage decreases, the field effect transistor Q ₁ connected in parallel to the resistor R ₂ of the amplifier circuit 3 gradually approaches cut-off, and the impedance between the source terminal and drain terminal connected to both ends of the resistor R ₂ decreases. growing. The amplification degree of the amplifier A ₁ of the amplifier circuit 3 is determined by the combined resistance value of the two resistors R ₁ and R ₂ and the resistor R ₃
As described above, when the impedance of the field effect transistor Q ₁ increases, the gain of the amplifier A ₁ decreases and the amplification degree of the amplifier circuit 3 decreases, and as a result, the device Detection sensitivity is lowered, and malfunctions caused by drastic fluctuations in the surface temperature of the dust suction mat installed within the detection area can be avoided. At this time, when a human body etc. enters the detection area, the signal due to the surface temperature difference between the background and the human body is sufficient compared to the detection level of the level detection circuit 4 even if the amplification degree of the amplifier circuit 3 is small. , so moving objects such as human bodies can be detected reliably.

When a moving object within the detection area is detected and an object detection signal is output from the level detection circuit 4, the detection signal turns on the transistor _Q3 of the sensitivity correction interrupt circuit 8, and the base of the transistor _Q2 is grounded. The output of amplifier _A2 is cut off. Therefore, the function of the detection sensitivity automatic correction circuit 7 is interrupted and the detection sensitivity is maintained constant at the time when the object detection signal was output. Here, if a human body continuously enters the detection area, the object detection signal is output almost continuously during that time, and the function of the detection sensitivity automatic correction circuit 7 continues to stop, and the human body from the detection area is continuously output. Since detection sensitivity continues to be maintained constant regardless of fluctuations in the amount of radiated infrared energy due to entry, each human body can be reliably detected.

When the human body stops entering the detection area, when the object detection signal is no longer output, that is, when the output of the level detection circuit 4 returns to the reference signal level, the transistor _Q3 becomes non-conductive and the sensitivity is corrected. The driving of the interruption circuit 8 is stopped, and the detection sensitivity automatic correction circuit 7 starts functioning again to prevent malfunctions caused by noise signals. The time during which the automatic detection sensitivity correction circuit 7 is interrupted by the sensitivity correction interruption circuit 8 can be adjusted as appropriate by varying the output time of the object detection signal from the level detection circuit 4.

It should be noted that the present invention is not limited only to the contents of the above description and drawings, and may include various modifications without departing from the scope of the claims. for example,
In the above embodiment, the automatic detection sensitivity correction circuit 7 is configured to adjust the amplification degree of the amplifier circuit 3. Good too. In other words, even if the detection sensitivity is corrected by increasing the detection level as the amount of variation in the amplified signal level increases, and conversely lowering the detection level when the amount of variation is small, it will function in exactly the same way. .

<Effects of the Invention> As described above, the infrared moving object detection device of the present invention can cope with signal fluctuations caused by background temperature changes even under conditions where the background temperature changes in the detection area are extremely drastic. Although the configuration corrects the detection sensitivity by moving the object into the detection area, the correction of the detection sensitivity is interrupted only when the movement of an object into the detection area is detected. can be reliably detected.

[Brief explanation of the drawing]

The figure is a block diagram of an embodiment of the present invention. 1...Optical system, 2...Infrared detection element, 3...
Amplifier circuit, 4... Level detection circuit, 5... Output circuit, 6... Controller, 7... Detection sensitivity automatic correction circuit, 8... Sensitivity correction interrupt circuit.

Claims (1)

[Claims] 1 An optical system that condenses infrared light flux emitted from a predetermined detection area, an infrared detection element that converts the amount of infrared energy incident through this optical system into an electrical signal proportional to the amount of variation, and an infrared detection element that amplifies this electrical signal. a level detection circuit that outputs an object detection signal when the amplified signal exceeds a predetermined detection level, and a controller that controls the opening and closing of automatic doors etc. by outputting this object detection signal. An infrared moving object comprising: an output circuit that outputs a signal; and an automatic detection sensitivity correction circuit that variably controls the gain of the amplifier circuit or the detection level of the level detection circuit in accordance with fluctuations in the amplified signal level of the amplifier circuit. In the detection device, the sensor is inserted and connected between the output terminal of the level detection circuit and the detection sensitivity automatic correction circuit, and is driven only when the object detection signal is output from the level detection circuit to the detection sensitivity automatic correction circuit. An infrared type moving object detection device, further comprising a sensitivity correction interrupting circuit that functions to maintain the output of this circuit at the signal level at the time when the object detection signal is output.