JPS60230081A - Infrared type moving body detection device - Google Patents

Abstract

PURPOSE:To stabilize an operation for the continuous movement of a body by stopping temporarily the output of a sensibility correcting circuit and by holding the detection sensibility for a certain time when an electric signal corresponding to the amount of change of a light beam exceeds the prescribed level and a level detecting circuit outputs a trigger signal. CONSTITUTION:An infrared ray detecting element 2 changes the light converged by an optics system 1 into an electrical signal proportional to the change amount of a light flux and transmits a trigger signal from a level detecting circuit 4 via an amplifier 3 when exceeding the prescribed detecting sensibility and transmits an opening and closing signal of a door from a controller 6 via output circuit 5. When the temp. change of a background becomes sharp an automatic regulating circuit 7 approaches a field effect transistor Q1 to cutoff, holds down the amplification of the amplifier circuit 3 and avoids erroneous operations, and also when a normal signal is inputted according to the movement of a body it conducts a transistor Q3 of a motion sensing correction stopping circuit 8 and holds the regulating circuit 7 to the detecting sensibility of the output time of trigger signal according to the time width of the output of a trigger signal.

Description

[Detailed Description of the Invention] A) Industrial Application Field This invention focuses on 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.

(ol) Conventional technology All objects above absolute zero (-273'O) emit infrared rays depending on their humidity, but human bodies and buildings at room temperature emit far infrared rays with a wavelength of around 10 μm. The infrared moving object detection device 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.There is no human body within the detection area. It is configured to detect changes in the amount of infrared energy caused by intrusion of objects such as objects, and issue a signal to open an automatic door or issue a signal to trigger a security alarm system.

Incidentally, recently, dust-absorbing mats made of chemically treated cloth are often installed in front of automatic doors. The fabric material of this dust-absorbing mat 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, if a detection area is set outdoors where the eyes are exposed to direct sunlight, and a dust suction mat is installed within this detection area, the infrared moving object detection device will detect temperature changes on the dust suction mat itself, and Automatic doors sometimes operated even though no objects were moving.

Therefore, we focused on the fact that false signals caused by dust-absorbing mats occur 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 detector. If there is a large temperature change, an automatic gain adjustment circuit is installed to reduce the detection sensitivity of the detector or reduce the level of the signal itself depending on the degree of change.
An infrared moving object detection device has been proposed in which the signal level and detection sensitivity are maintained relatively around -er regardless of the magnitude of temperature change.

p~ Problem to be Solved by the Invention In a conventional device equipped with an automatic gain adjustment circuit, when an object continuously moves into the detection area, the automatic gain adjustment circuit does not function due to the normal signal associated with the movement of the object. , the detection sensitivity gradually decreases, eventually leading to a situation where no detection is possible at all.

An object of the present invention is to provide an infrared moving object detection device equipped with an automatic gain adjustment circuit that operates stably even when objects continuously move into a detection area. It's about doing.

(E)) Structure The infrared moving object detection device of the present invention includes an optical system that condenses infrared light flux emitted from a predetermined detection area, and converts the incident infrared light flux into an electrical signal according to the amount of variation thereof. An infrared seed/output element, an amplifier circuit that amplifies this converted electrical signal, a level detection circuit that outputs a trigger signal when the amplified signal exceeds a predetermined level, and a trigger signal received from the level detection circuit. It consists of an output circuit that outputs an operating signal to a controller that controls the opening and closing of an automatic door, etc., and a sensitivity correction circuit that corrects detection sensitivity in accordance with the amount of variation in the amplified signal of the amplifier circuit, and the level detection circuit. The present invention is characterized in that it includes a sensitivity correction interruption circuit that temporarily interrupts the output of the sensitivity correction circuit when the trigger signal is output, and maintains the detection sensitivity for a certain period of time when the trigger signal is output.

(f) Example Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of an infrared moving object detection device according to the present invention.

The infrared light flux emitted from the predetermined detection area is sent to optical system 1.
The light is focused and incident on the infrared detection element 2. An infrared detection element such as a two-pin pyroelectric detector, a thermistor, a bolometer, or a thermoelectric stack converts the incident infrared light flux into an electrical signal proportional to its variation.

The amplified signal amplified by the amplifier circuit 3 is monitored by a level detection circuit 4 for the signal strength, that is, the amount of variation in infrared light flux, and when the level detection circuit 4 detects a variation exceeding a predetermined detection sensitivity, it generates a trigger signal having a predetermined time length. Output. The output circuit 5 is activated by the trigger signal of the 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.

In the infrared moving object detection device having the basic configuration as described above, the automatic gain adjustment circuit 7 added to the amplifier circuit 3 is a sensitivity correction circuit, and the sensitivity correction interruption circuit 8 is connected to the output side of the level detection circuit 4 and the automatic gain adjustment circuit. It is connected between the adjustment circuit 7 and the adjustment circuit 7.

(G1 Effect Next, the operation of the above embodiment will be described.

When the temperature change of the background set as the detection area increases, the amplified signal of the amplifier circuit 3 increases accordingly, and the output of the amplifier A2 of the automatic gain adjustment circuit 7 also increases. When the output of amplifier A2 increases, transistor Q2 becomes conductive and the collector voltage decreases. As the collector voltage of transistor Q2 decreases, field effect transistor Ql gradually approaches cutoff, and the impedance between the source and drain terminals increases. The amplification degree of amplifier A2 of amplifier circuit 3 is determined by the combined resistance of resistors R1 and R2 and resistor R.
3, so when the impedance of the field effect transistor Q1 increases, the gain of the amplifier A1 decreases, the amplification degree of the amplifier circuit 3 is suppressed, and malfunctions due to background temperature changes are avoided. However, since the automatic gain adjustment circuit 7 functions in the same way due to a regular signal accompanying the movement of an object into the detection area, the above-mentioned problem will not occur if an object continues to move into the detection area. Ta.

Therefore, in the present invention, while the level detection circuit 4 detects the movement of an object into the detection area and outputs a trigger signal, the sensitivity correction function of the automatic gain adjustment circuit 7 is temporarily suspended, and the detection sensitivity at the time of outputting the trigger signal is adjusted. is held for a certain period of time. A sensitivity correction interrupt path 8 connected between the output of the level detection circuit 4 and the base terminal of the transistor Q2 of the automatic gain adjustment circuit 7 is the gist of the invention. Now, when the level detection circuit 4 detects the movement of the object into the detection area and outputs a trigger signal, the transistor Q3 becomes conductive, so the transistor Q2 is cut off, and the amplifier A2
output is cut. Therefore, the automatic gain adjustment circuit 7 is maintained at the detection sensitivity at the time when the trigger signal is output from the level detection circuit 4, and does not function based on a normal signal accompanying the movement of an object into the detection area. Note that when the trigger signal of the level detection circuit 4 returns to the reference level, the transistor Q2 becomes conductive and the automatic gain adjustment circuit 7 functions again. Therefore, by appropriately determining the output time of the trigger signal, the sensitivity of the automatic gain adjustment circuit 7 can be adjusted. You can adjust the correction interruption time.

In the above embodiment, the amplifier circuit 3 is used as the sensitivity correction circuit.
Did you mention an example of a configuration that adjusts the amplification degree of
The present invention is not limited to this example, but the amplifier circuit 3
This method monitors the fluctuation of the amplified signal of the amplifier circuit 3 and changes the detection level of the level detection circuit 4 according to the amount of fluctuation. If the amount is small, the detection sensitivity is corrected by lowering the detection level, and it functions in exactly the same way. Even under conditions where the background temperature changes extremely rapidly, such as when a detection area is set outside the irradiation area and a dust-absorbing mat is installed within this detection area, the signal fluctuations caused by the background temperature changes will not be affected. The detection sensitivity is corrected by the sensitivity correction circuit when the object moves into the detection area, and the sensitivity correction interruption circuit interrupts the function of the sensitivity correction circuit when the object moves into the detection area, so infrared moving object detection operates extremely stably. It is possible to provide the equipment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an infrared moving object detection device according to the present invention. 1... Optical system 2... Infrared detection element 5... Output circuit 6... Controller 7... Sensitivity correction circuit 8... Sensitivity correction interruption circuit A1
, A2...Amplifier Ql...Field effect transistor Q2, Q3...Transistor patent applicant OPTEFUX Co., Ltd.

Claims (1)

[Claims] An optical system that focuses infrared light flux emitted from a predetermined detection area, an infrared detection element that converts the incident infrared light flux into an electrical signal according to the amount of variation thereof, and an amplifier circuit that amplifies this converted electrical signal. , a level detection circuit that outputs a trigger signal when the amplified signal exceeds a predetermined level, and an output circuit that receives the trigger signal from the level detection circuit and outputs an activation signal to a controller that controls the opening and closing of automatic doors, etc. Tokaranashi, it has a sensitivity correction circuit that corrects the detection sensitivity in response to the amount of variation in the amplified signal of the amplifier circuit, and temporarily interrupts the output of the sensitivity correction circuit when the level detection circuit outputs a trigger signal, An infrared moving object detection device characterized by comprising a sensitivity correction interruption circuit for maintaining detection sensitivity for a certain period of time when a trigger signal is output.