JP2875385B2 - Security system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a security system that monitors the presence or absence of a trespasser in a guard area using a passive infrared detection sensor and issues an alarm when a trespasser is detected. Things.

<Prior Art> A passive infrared detection sensor in such a security system may be destroyed by a person who intends to illegally intrude, with the intention of preventing an alarm from being issued. For example, during the daytime when the security system is turned off because it is necessary to freely enter and exit the guard area, destroy the sensor, short-circuit or change the detection area to an unnecessary point, or attempt to enter at night. May be used.

As a measure to prevent this from happening,
A so-called tamper (mischief) protection structure in which the alarm sounds by simply removing the sensor cover, or a heat source is provided inside the passive infrared detection sensor, and this heat source is periodically driven to detect abnormalities in the operation of the sensor itself. It has a function to check whether or not it exists.

<Problems to be Solved by the Invention> However, when the infrared transmitting window to the infrared detecting element of the sensor is shielded so that the infrared is not transmitted by means such as spraying paint from the outside of the cover, the tamper protection described above. The structure is useless.On the other hand, in the case of a sensor with a heat source inside, despite the fact that the human body can not be detected, the internal heat source gives a judgment result of no abnormality at the regular check, so the sensor The inconvenience of noticing the abnormality occurs.

The present invention has been made in view of such a conventional problem, and even when a passive infrared detection sensor is shielded from an infrared transmitting window by a unit that does not contact the cover from the outside, the passive infrared detection sensor reliably detects the window. It is another technical object of the present invention to provide a security system capable of automatically correcting the detection sensitivity of a sensor to be constant in accordance with a change in background temperature of a detection area.

<Means for Solving the Problems> In order to solve the above problems, the security system of the present invention is a security system that detects an intrusion of a human body or the like in a security area and outputs an alarm. It is equipped with a passive infrared detection sensor and is installed mutually so that the other infrared detection sensor enters the detection area of one infrared detection sensor, and at least one of these infrared sensors has a heating element integrated with it. When the heating element is driven and the other infrared detection sensor having the heating element provided in the detection area does not output a detection signal, there is an abnormality. And a controller for determining

The controller may further include sensitivity correction means for variably controlling the detection sensitivity of the infrared detection sensor so that the light receiving signal level of the infrared detection sensor when the heating element reaches a predetermined temperature is within a predetermined range. it can.

<Operation> When the infrared transmission window of the cover is shielded due to adhesion of paint by spraying or the like, for example, in a periodic test mode, the infrared light generated by the heating element driven by the controller passes through the infrared transmission window of the sensor. The controller does not output a detection signal in spite of the fact that the heating element is driven from this sensor, so that the controller determines that the sensor is abnormal. On the other hand, when the detection signal is output from the sensor, the controller determines that the sensor is normal.

Also, if the controller is provided with sensitivity correction means, after the controller determines that the sensor is normal in the test mode, the sensitivity correction means sets the detection sensitivity of the sensor so that the light reception signal level of the sensor falls within a predetermined range. Variable. Here, the controller determines whether the signal level of the sensor when the temperature of the heating element becomes constant is within a predetermined range regardless of a change in the background temperature of the detection area due to the season, the weather of the day, or the like. Therefore, the light receiving signal level of the passive infrared sensor for detecting the difference between the background temperature and the heating element temperature changes according to the background temperature, and when the signal level goes out of the predetermined range, the sensitivity correction means sets the predetermined range. The detection sensitivity of the sensor is variably controlled to be within the range, and the detection sensitivity of the sensor is automatically corrected so as to be always constant according to the season and temperature.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block configuration of an embodiment of the present invention,
The room R in the guard area is shown as a plane. In a corner of the room R, a passive infrared detection sensor 1 is arranged with its detection areas E1 to E3 set at a place to be watched in the room R, and in one of these detection areas E3. A heating element 2 having a heating wire incorporated therein and a temperature sensor 3 for measuring a temperature generated by the heating element 2 are provided on the wall surface of the room R.

As shown in the block diagram in FIG. 1, the passive infrared detection sensor 1 converts the amount of infrared energy from the detection areas E1 to E3 condensed and incident by the optical system 1a into an electric signal proportional to the fluctuation thereof. An infrared detecting element 1b, an amplifier 1c for amplifying an electric signal (light receiving signal) from the infrared detecting element 1b, and constantly monitoring the fluctuation of the amplified signal to output a detection signal when a fluctuation exceeding a set detection level is detected. And a level detection circuit 1d.

The controller 3 is configured as follows. That is,
The central processing unit 3a composed of a microcomputer
d, which controls the entire system based on a program stored in advance.The clock signal from the clock circuit 3b and the RAM 3c
The test mode is set when the test time comes according to the test time data stored and stored in the memory. When it is determined that the sensor 1 is abnormal based on the result of the test mode, a buzzer or an indicator light is output through the output circuit 6. Become an alarm 7
To notify the abnormality. Normally, when a detection signal is output from the sensor 1, an alarm device 5 including a buzzer or an illuminator is driven via an output circuit 4 to issue an alarm.

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. In the RAM 3c, for example, a test time such as a time at which a daily alert state is started or a time every two hours is set and stored in advance.
Whether or not the test time is reached is constantly monitored based on the test time data from c and the clock signal from the clock circuit 3b (step S1).
Command (step S2), a test mode other than the normal operation is set, and it is determined whether or not the measured temperature of the temperature sensor 3 has reached a set temperature previously set and stored in the RAM 3c (step S3).

This set temperature is set to a temperature that generates substantially the same infrared rays as the human body. Therefore, when the heating area of the heating element 2 is small, the temperature is set slightly higher than the human body temperature of 36 ° C. The central processing unit 3a controls to increase the power supplied to the heating element 2 until the temperature measured by the temperature sensor 3 reaches the set temperature.

Then, when the temperature measured by the temperature sensor 3 of the heating element 2 reaches the set temperature, it is determined whether or not the passive infrared detection sensor 1 has output a detection signal (step S4). If the sensor 1 is normal, the infrared ray generated by the heating element 2 is detected and a detection signal is output.
It is determined whether or not the difference between the sensor signal level output from the controller and the detection level set in the level detection circuit 1d is within a predetermined range (step S5). Here, the temperature of the heating element 2 is controlled by the central processing unit 3a so as to be always constant irrespective of a change in the background temperature of the detection area due to the season, the weather, or the like. The sensor signal level of the passive infrared sensor 1 for detecting the difference between
It changes according to the background temperature, and if the detection level is constant, the difference from the sensor signal level falls outside a predetermined range. In that case, the level detection circuit 1d is set so that the above-mentioned difference falls within a predetermined range.
Is changed, and the detection sensitivity is automatically corrected (step S6). Accordingly, the detection sensitivity of the sensor 1 is regularly and automatically corrected so that the detection sensitivity is always constant regardless of the season or the weather. Thereafter, the power supply to the heating element 2 is stopped (step S7), and the next test time is waited. Therefore, the test mode is set at regular intervals and the above-described test operation is performed.

Should the sensor 1
When the infrared transmitting window of the cover is shielded, the heating element 2 is driven by the central processing unit 3a in the above-described test mode, but the infrared rays generated by the heating element 2 do not pass through the infrared transmitting window. It is shut off, and it is determined that there is an abnormality due to no detection signal from the sensor 1 in step S4, and the alarm 7 is driven via the output circuit 6 to notify the abnormality (step S8).

On the other hand, other than the test time, it functions as a normal security system. That is, it is always determined as NO in step S1, and it is constantly monitored whether or not the detection signal is output from the sensor 1 (step S9). When the detection signal is output, the alarm 5 is driven via the output circuit 4. And issue an alarm (Step S1
0).

3 and 4 show another embodiment of the present invention.
In this example, the passive area infrared sensors 8 and 9 are used to monitor a guarded area, and the detection areas E4 to E6 and E7 to E9 of each of the sensors 8 and 9 can monitor most of the room. . As shown in FIG. 4, a heating element 11 composed of a heater is integrally incorporated into each of the sensors 8 and 9 below the infrared detecting element 10, and a cover 12 is provided at a position facing the heating element 11. An openable and closable shutter 13 is provided.
The cover 12 is provided with a condensing lens 14 at a location facing the infrared detecting element 10 and a display window 16 at a location facing the operation indicator 15 as in the existing one.

Then, as shown in FIG. 3, the sensors 8, 9 are attached to the wall surfaces in the mutual detection areas E6, E9. Therefore, it is not necessary to separately provide only the heating element 2 as shown in FIG. 1, and the shutter 13 is moved when the heating element 11 reaches a predetermined temperature by a driving mechanism (not shown) made of a shape memory alloy or the like. The test of each sensor 8, 9 which is automatically opened and eliminates the need for a temperature sensor is performed in substantially the same manner by the controller 3 as shown in FIG.

FIG. 5 shows still another embodiment of the present invention. In addition to monitoring the alert area by the detection areas E1 to E3 and E10 of the passive infrared detection sensor 1, in particular, the window 17 and the doorway 18 are connected to the projector 19 to receive light. When monitoring with the photoelectric switch consisting of the device 20,
By incorporating the heating element 21 integrally with the projector 19 installed in the detection area E3 of the sensor 1, the trouble of separately disposing the heating element 21 alone is eliminated. When the heating element is integrally attached in this way, the sensor may be covered with a box or the like, sprayed with paint or the like to block infrared rays, or covered just before the direction in which the sensor area is formed. Even if there is physical interference between the and the detection area, these can be reliably detected. That is, the overall detection performance including the cover of the detection sensor is maintained, and the sensitivity can be set.

In each of the above embodiments, the case has been described in which the passive infrared detection sensor and the controller are provided separately, but it is a matter of course that the sensor and the controller can be integrated.

<Effects of the Invention> As described above, according to the security system of the present invention, two passive infrared detection sensors are provided in the guard area,
The other infrared detection sensors are installed so as to enter the detection area of one of the infrared detection sensors, and among these infrared sensors, at least one of the infrared detection sensors is provided with a heating element integrally, When the heating element is driven, an infrared detection sensor provided with the heating element in the detection area is provided with a controller that determines that there is an abnormality when the other infrared detection sensor does not output a detection signal. Therefore, even if there is physical interference between the sensor and the detection area, these can be reliably detected, and the overall detection performance including the cover of the detection sensor is maintained, Reliability can be improved.

Further, the controller is provided with sensitivity correction means for variably controlling the detection sensitivity of the infrared detection sensor so that the light receiving signal level of the infrared detection sensor when the heating element reaches a predetermined temperature is within a predetermined range. In this case, the detection sensitivity of the sensor can always be kept constant in response to a change in the background temperature of the detection area due to the season or weather, and a more reliable security system can be realized.

[Brief description of the drawings]

 FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flowchart of the embodiment, FIG. 3 is a schematic diagram of another embodiment of the present invention, FIG. FIG. 5 is a schematic configuration diagram of still another embodiment of the present invention. 1,8,9 ... passive infrared detection sensor 2,11,21 ... heating element 3 ... controller 5 ... alarm

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Amano 4-7-5 Nonohama, Otsu City, Shiga Prefecture Inside Optex Co., Ltd. (56) References JP-A-63-18498 (JP, A) 168491 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G08B 1/19 G01V 9/04

Claims (2)

(57) [Claims] 1. A security system for detecting an intrusion of a human body or the like in a security area and outputting an alarm, wherein the security area is provided with two passive infrared detection sensors, and one of the detection areas of one infrared detection sensor is within the detection area of the other infrared detection sensor. At least one of these infrared sensors is provided integrally with a heating element, and the heating element is provided when the heating element is driven. A security system comprising: a controller for determining that there is an abnormality when another infrared detection sensor having an infrared detection sensor provided in a detection area does not output a detection signal. 2. The controller according to claim 1, wherein said controller comprises a sensitivity correction means for variably controlling the detection sensitivity of said infrared detection sensor such that a light receiving signal level of said infrared detection sensor when said heating element reaches a predetermined temperature is within a predetermined range. The security system according to claim 1, wherein the security system is provided.