JPH05325053A - Burglar sensor - Google Patents

Abstract

PURPOSE:To provide the burglar sensor which can detects a trespasser in an early stage and is hardly found by the trespasser. CONSTITUTION:A sensing part 12 is embedded in a roof 2. The sensing part 10 is equipped with at least one detection element 1 where an internal electrode 11 and an external electrode 12 are arranged closely almost on the same plane. A pulse voltage is applied to the external electrode 12 and a detecting circuit 3 detects variation in the crest value of the detected current of the internal electrode 11 to detect the trespasser being on the roof 2. The detecting circuit 3 once detecting the trespasser on the roof 2 generates a warning signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a security sensor for warning an intruder of a building such as a house.

[0002]

2. Description of the Related Art Generally, as a crime prevention sensor, there is provided a type that generates an alarm signal when a window is opened or a window is broken and a type that uses infrared rays or ultrasonic waves to warn an intruder. There is.

[0003]

The former security sensor is
There is a problem that the alarm signal is delayed because the intruder cannot be detected until the intruder opens the window or breaks the window glass. In the latter security sensor, an alarm signal is generated early, but there is a problem that false detection is likely to occur for small animals such as dogs and cats, and the part that generates infrared rays and ultrasonic waves is exposed. There is a problem that an intruder is likely to be found and may invade the surveillance area.

The present invention is intended to solve the above problems, and an object thereof is to provide a crime prevention sensor which can detect an intruder at an early stage and is hard to be detected by the intruder.

[0005]

According to the present invention, in order to achieve the above object, a sensing section having a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, and one electrode of the sensing element are provided. It is equipped with a detection circuit that applies a pulse voltage and generates an alarm signal based on the decrease in the peak value of the detection current at the other electrode due to the approach of the human body. Is buried.

[0006]

According to the above construction, since the sensing part having the sensing element for detecting the approach or contact of the human body is buried in the important part of the part of the construction which faces the outside, an intruder may open the window or It is possible to detect an intruder early before breaking the window glass, and how the monitoring area is set because the sensing part is embedded in the key part of the part facing the outside. The intruder never knows if they are present. Moreover, since the monitoring area is limited to a relatively short distance from the surface of the building, a passerby or the like is not erroneously detected. Moreover, since the sensing unit includes the sensing element in which the electrodes are arranged close to each other on the same plane, the sensing unit can be formed in a sheet shape and there are few restrictions on the installation location of the sensing unit.

[0007]

EXAMPLE In this example, as shown in FIG. 1A, a sensing unit 10 having a sensing element 1 is laid over substantially the front surface of a roof 2 of a house, which is a construction object, and the sensing unit 10 is used. An alarm signal is generated based on the detection result of. The sensing unit 10 may be installed at any location facing the exterior of a building such as a gatepost, gate, cobblestone, fence, outer wall, shutter, door, door knob, window glass, window frame (sash). You can choose to embed in these places.

The sensing element 1, as shown in FIG.
The inner electrode 11 and the outer electrode 12 that surrounds the outer circumference of the inner electrode 11 over the entire circumference are formed in a substantially sheet shape. The inner electrode 11 and the outer electrode 12 are laminated or embedded in a base 13 made of an insulator. As shown in FIG. 3, the inner electrode 11 is connected to the base of a transistor Q for detection, and a pulse voltage of a rectangular wave is applied to the outer electrode 12 as a drive signal drv. That is, the drive signal dr
When v is applied to the outer conductor 12, a current corresponding to the rising and falling of the drive signal drv is detected in the inner conductor 11.

If there is no object around the sensing element 1, the charge is distributed only between the inner electrode 11 and the outer electrode 12 as shown in FIG. On the other hand, FIG.
As shown in (b), when an object such as a human body having a large earth-to-ground capacitance approaches the sensing element 1, a capacitor is formed between the outer electrode 12 and the object. Since this capacitor functions as a bypass capacitor to the ground, the peak value of the current detected by the inner electrode 11 corresponding to the rising and falling of the drive signal drv should be lower than that when there is no object. Become.
That is, when there is no object, the peak value of the current is
If it is as shown in (a), the peak value is reduced as shown in FIG. 5 (b) when the object exists. Therefore, the presence or absence of the object can be determined based on the peak value of the detection signal sen output from the collector of the transistor Q.

That is, the detection signal sen is input to the detection circuit described later. In the detection circuit, the detection signal at power-on
The reference value obtained based on the peak value of sen (that is, the peak value of the detected current) is stored, and the peak value of the subsequent detection signal sen and the reference value are compared. When the peak value of the detection signal sen becomes smaller than the reference value, it is considered that the object is approaching and the binary output signal is inverted. The load can be turned on / off by controlling a switching element such as a relay by this output signal.

The sensing section 10 is constructed by using at least one sensing element 1 described above. Sensing unit 1 using a large number of sensing elements 1
When forming 0, the detection elements 1 may be arranged in a matrix as shown in FIG. If the sensing unit 10 including a large number of sensing elements 1 is formed, it is possible to offset variations in the detection results of the individual sensing elements 1 to stabilize the sensing sensitivity and detect an object having a large area. .. In this case, the sensing element 1 may be scanned row by row or column by column to detect a state change.
Even if a large number of sensing elements 1 are provided, the whole can be formed in a sheet shape.

As shown in FIG. 1B, the driving signal drv from the detection circuit 3 including a microcomputer is applied to the outer electrode 12 of the sensing section 10. Drive signal
drv is a rectangular wave with a period of 20 msec. Since the base of the transistor Q is connected to the inner electrode 11, the detection signal sen is obtained from the collector of the transistor Q, and the signal corresponding to the peak value of the detection signal sen is input to the detection circuit 3 through the signal processing unit 4. It In the signal processing unit 4, based on the signal of the differential waveform as shown in FIG. 5 generated in response to the rising and falling of the drive signal drv,
A rectangular wave signal having a peak value proportional to the peak value of the differential waveform is output. In the detection circuit 3, the reference value created as described above and the peak value of the detection signal sen are compared each time the drive signal drv is transmitted, and the peak value becomes 1 or less when the drive signal drv is sent.
If it continues for more than 00 msec (that is, if the peak value is less than or equal to the reference value for five or more drive signals drv), it is determined that an intruder is present and an alarm signal is generated. That is,
An alarm signal sounds an alarm bell, reports to a security company, or activates a sounding device or a light emitting device to intimidate an intruder.

On the other hand, after detecting an intruder, the detection signal se
When the peak value of n is below the reference value for 100 msec or more, the detection circuit 3 determines that the intruder is out of the detection area and cancels the alarm signal. According to the above configuration, the sensing unit 10 can be formed in a sheet shape, and the size and the number of the sensing elements 1 can be set arbitrarily, so that the sensing unit 10 can be arranged at any place and the degree of freedom of the installation place is high. Moreover, the intruder can be detected early by installing it outdoors. Further, since the intruder is detected based on the change in capacity, it can be embedded in the wall surface or the like, which makes it difficult for the intruder to notice and can reliably detect the intruder. Furthermore, since it is possible to easily distinguish a person from other small animals or leaves of trees according to the degree of change in capacity, the probability of false alarm is small.

[0014]

As described above, according to the present invention, since the sensing portion provided with the sensing element for detecting the approach or contact of the human body is embedded in the important part of the part of the building which faces the outside, the intruder can There is an advantage that an intruder can be detected early before opening the window or breaking the window glass. Moreover, since the sensing unit is buried in a key part of the part facing the outdoors, the intruder does not know how the monitoring area is set, so the intruder can avoid the sensing unit. Intruders can be reliably detected without intruding. Furthermore, since the monitoring area is limited to a relatively short distance from the surface of the building, it does not cause erroneous detection of pedestrians, etc. Since they can be identified, there is an advantage that the probability of false alarms is small. In addition, since the sensing unit includes the sensing element in which the electrodes are arranged close to each other on the same plane, there is an advantage that the sensing unit can be formed in a sheet shape and there are few restrictions on the installation place of the sensing unit.

[Brief description of drawings]

FIG. 1 shows an embodiment, (a) is a perspective view showing an example of an installed state, and (b) is a circuit diagram.

FIG. 2 is a plan view of a sensing element used in the embodiment.

FIG. 3 is a circuit diagram of a main part of the embodiment.

FIG. 4 is a diagram illustrating the principle of the embodiment.

FIG. 5 is an operation explanatory diagram of the embodiment.

FIG. 6 is a plan view showing an example of a sensing unit used in the example.

[Explanation of symbols]

 1 Detection element 2 Roof 3 Detection circuit 10 Sensing part

[Procedure amendment]

[Submission date] June 1, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

[0005]

According to the present invention, in order to achieve the above object, a sensing section having a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, and one electrode of the sensing element are provided. It is equipped with a detection circuit that applies a pulse voltage and generates an alarm signal based on the decrease in the electrostatic capacitance between both electrodes due to the approach of the human body, and the sensing part is embedded in the important part of the part of the building that faces the outdoors. -ing

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

If there is no object around the sensing element 1, the charge is distributed only between the inner electrode 11 and the outer electrode 12 as shown in FIG. On the other hand, FIG.
As shown in (b), when an object such as a human body having a large earth-to-ground capacitance approaches the sensing element 1, a capacitor is formed between the outer electrode 12 and the object. Since this capacitor functions as a bypass capacitor to the ground, the capacitor between the inner electrode 11 and the outer electrode 12 is
Capacitance will be lower than when there is no object
And when the drive signal drv rises and falls
The current flowing through the base of the transistor Q of is reduced. Shi
Therefore, the detection signal that is the collector output of the transistor Q is
No. sen has a wave height as shown in Fig. 5 depending on the presence or absence of an object.
The value changes.

Claims (1)

[Claims] 1. A sensing unit including a sensing element in which a pair of electrodes are arranged in close proximity to each other on a substantially same plane, and a pulse voltage is applied to one electrode of the sensing element to detect the other electrode when a human body approaches. A crime prevention sensor, comprising: a detection circuit that generates an alarm signal based on a decrease in the peak value of an electric current; and a sensing unit embedded in a key part of a part of the construction that faces the outside.