JPH05151469A - Signal processor for pneumatic sensor of alarm device - Google Patents

Abstract

PURPOSE:To reduce the occurrence of malfunction of an alarm device incorporated with signal processor, in the signal processor of a pneumatic sensor for an alarm device outputting a signal after comparing the pneumatic sensor's output with a reference value. CONSTITUTION:The first detector 53 which detects the high signal of a pair of high and low signals generated by a penumatic sensor 11 when a door is opened, the second detector 55 which detects a low signal, the first and second signal holding means 23 and 25 which respectively hold the detection signals of the first and second detectors 53 and 55 for a specified period and an AND circuit 17 which outputs alarm output signal only while the first and second signal holding means 23 and 25 hold the detection signal are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air pressure sensor, and more particularly to a signal processing device of an air pressure sensor for an alarm device which detects an intruder into the room by detecting a change in the air pressure inside the room due to opening of a door. ..

[0002]

2. Description of the Related Art Japanese Patent Application No. 2-294510 discloses a device for detecting the presence or absence of an intruder in a room by detecting a change in air pressure in the room due to opening of a door or the like. This signal processing device is roughly composed of an amplifier and a comparator. As shown in FIG. 5, an air pressure sensor (11) detects changes in the air pressure in the room due to the opening of the door when the intruder enters the room.
The output of the air pressure sensor (11) is amplified by the amplifier (12), the amplified output is compared with the reference voltage by the comparator (13), and it is determined that the output is larger than the reference voltage. If it does, it outputs a detection signal.

The operation of the intrusion alarm device employing this signal processing device (14) will be described in detail below. For example, when a hinged door is opened, the air in the room is slightly sucked and discharged to the outside by the open door, the air pressure in the room changes, and a predetermined frequency (10 to 0. 1n
Hz) weak air vibration is generated.

It is also known that even when a sliding door type door is opened, a weaker air vibration is generated in the room. Therefore, when an intruder opens the door, the air pressure in the room changes, and the air pressure sensor (11) is activated accordingly to generate an output signal. Amplify this output signal and compare
Compare with reference voltage in (13).

As this reference voltage, a threshold voltage having a constant potential other than zero potential is adopted, and it is determined that the air pressure has changed when the magnitude of the output signal is higher than the threshold voltage. Activate the intrusion alarm device. However,
In the intrusion alarm device employing this signal processing device (14), malfunction easily occurs.

This is because the operation of the air pressure sensor (11) has a high temperature dependency and the output signal is generated only by the temperature change. For example, lead zirconate titanate or the like as a piezoelectric element used in the pressure detection portion of the air pressure sensor (11) often has pyroelectric characteristics in addition to piezoelectric characteristics, and therefore, changes in ambient temperature can be prevented. The effect may generate pyroelectricity and generate a signal.

Therefore, the air pressure sensor (11) by the wind of the air conditioner, etc.
When the temperature is changed, the air pressure sensor (11) outputs an output signal, and this output signal is processed by the signal processing device (14), and a detection signal is output even when the door is not opened. From this, the above-mentioned malfunction occurs. [Regarding the Invention of Claim 1] In view of the above point, the invention of Claim 1 is a "signal processing device for an air pressure sensor for an alarm device which outputs an output signal by comparing the output of the air pressure sensor (11) with a reference value". It is an object of the invention to reduce the occurrence of malfunction of an alarm device incorporating the signal processing device.

[0008]

[Technical Means] To solve the above-mentioned problems, the technical means of the invention of claim 1 is "of a pair of high and low signals generated from an air pressure sensor (11) in association with opening of a door for entrance and exit into a room. The first detector (13) for detecting the previous signal, the second detector (15) for detecting the subsequent signal, and the first detector (1
Signal holding means (16) for holding the detection signal of 3) for a certain period of time,
An AND circuit (17) for outputting an alarm output signal is provided only when the output from the signal holding means (16) and the detection signal of the second detector (15) are present ”.

[0009]

The above technical means operates as follows. When an intruder opens the door and tries to enter the room, weak air vibration occurs in the room, as described above. Then, the air pressure sensor (11) detects the air vibration, and at least a pair of high and low signals corresponding to the peak portion and the valley portion of the pressure wave due to the vibration are output from the air pressure sensor (11).

Of the at least one pair of signals corresponding to the peak portion and the valley portion of the pressure wave, the signal that occurs first is the air pressure sensor.
When output from (11), the output signal is applied to the first detector (13) and the auxiliary comparator (15). Then, the output signal of the air pressure sensor (11) is detected by the first detector (13), and the detection signal is held by the signal holding means (16) for a fixed time.

Next, of the at least one pair of signals corresponding to the peak portion and the valley portion of the pressure wave, when a signal generated later is output from the air pressure sensor (11), the signal is output from the second detector (15). )
Then, the second detector (15) outputs a detection signal. Then, the signal holding means (16) holds the detection signal of the first detector (13) for a certain time.
Applied to the AND circuit (17) together with the output of
Since the output signal is applied from both (15) and the signal holding means (16), a detection signal is output from the AND circuit (17).

On the other hand, the air pressure sensor (1
When 1) changes in temperature, the output of the air pressure sensor (11) rises or falls, and a single signal corresponding to the rise or fall of the output emerges from the air pressure sensor (11). Then, similarly to the above, a signal is output from the first detector (13) and the output signal is held in the signal holding means (16).

In this case, since it usually takes a long time to turn off the heater and stop the operation of the heater, the signal holding means (16) generally outputs the signal. The heater and the like are not stopped within the holding time, and the signal corresponding to the stop of the operation is not output from the second detector (15). Therefore, in this case, no detection signal is output from the AND circuit (17).

[0014]

[Effect] As the door is opened, an alarm signal is output only when a pair of high and low signals output by the air pressure sensor (11) are detected, so the air pressure sensor (11) changes in temperature due to the wind of the heater or air conditioner. Even in such a case, there is no inconvenience of outputting a detection signal, and there is less concern that the alarm device incorporating the air pressure sensor (11) will malfunction. [Invention of Claim 2] The invention of Claim 2 shares the industrial field of use and the problem to be solved with the invention of Claim 1, and the technology of the invention of Claim 2 adopted for that purpose. The objective means is "a first detector (53) that detects a high signal of a pair of high and low signals generated from the air pressure sensor (11) when the door for opening and closing the room is opened, and a low signal is detected. A second detector (55), a first signal holding means (23) for holding the detection signal of the first detector (53) for a certain period of time, and a detection signal of the second detector (55) for a certain period of time Second signal holding means (25), and the first and second signal holding means (23) (25)
Is provided with an AND circuit (17) which outputs an alarm output signal only when the detection signal is held.

[0015]

[Operation / Effect] The above technical means has the following operation / effect. When a pair of high and low signals are output from the air pressure sensor (11) due to opening of the door, these respective signals are transmitted to the first detector (53) and the second detector (53).
The detection signals are detected individually by the detector (55), and the detection signals are individually held by the first and second signal holding means (23) (25) for a fixed time.

In this case, whichever of the above-mentioned high and low signals is output from the air pressure sensor (11) first, the detection signals of the first detector (53) and the second detector (55) for detecting them are the first. Since the signal holding means (23) and the second signal holding means (25) hold the signal, a later signal is output from the air pressure sensor (11) to detect it (the above-mentioned signal. If a detector opposite to the detector that has detected the) is held by the corresponding signal holding means, these first and second signal holding means
The AND signals of (23) and (25) are output from the AND circuit (17).

That is, an alarm output signal is generated. On the other hand, when the output of the air pressure sensor (11) changes due to the wind of the heater or the like, only a single signal is output from the air pressure sensor (11) as described in the action of claim 1. The output signals of the first and second signal holding means (23) and (25) are not simultaneously applied to the AND circuit (17), and the alarm signal is not erroneously output.

Further, according to the invention of claim 2, in addition to the effect of the invention of claim 1, there is the following effect. Since both the detection signals of the first detector (53) and the second detector (55) are held by the first and second signal holding means (23) (25), the air pressure sensor is accompanied by the opening of the door. Of the pair of signals generated from (11), whichever of the high and low signals is generated first, this is held by the first signal holding means (23) or the second signal holding means (25). ..

Therefore, there is an advantage that it is not necessary to consider whether the signal generated earlier is high or low.

[0020]

Embodiments of the present invention described above will now be described in detail with reference to the drawings. In the following examples, the case where the present invention is applied to a room having an open door is described.
Therefore, when the door is opened, first, the air pressure in the room is lowered, and subsequently the air pressure is raised, and a signal corresponding to this is output from the air pressure sensor (11).

In the first embodiment of the present invention, as shown in FIG. 1, the signal processing device (14) is composed of an electronic circuit, and the output from the air pressure sensor (11) is converted by the conversion circuit (18). It is converted into a voltage, and this is branched into a first comparator (33) and a second comparator (35), and any one of them is processed.
A reference voltage set by shifting the output of the conversion circuit (18) when the air pressure sensor (11) does not operate is set up and down by the reference voltage setter (20) (21) and the reference voltage is set to It is applied to the first comparator (33) and the second comparator (35).

In this embodiment, the first comparator (33)
The combination of the reference voltage setting device (20) and the corresponding reference voltage setting device (20) corresponds to the first detector (53) described in the technical means section. In addition, the combination of the second comparator (35) and the corresponding reference voltage setting device (21) is the second combination described in the above-mentioned technical means.
Corresponds to the detector (55). First with low reference voltage
A mono-multivibrator (hereinafter abbreviated as MM) (10) that functions as a signal holding means (16) is connected to the comparator (33), and the signal of the MM (10) is supplied to the second comparator ( It is applied to the AND circuit (17) together with the signal of 35). Here, the details of the air pressure sensor (11) will be described below.

As shown in FIG. 1, the air pressure sensor (11) is composed of a piezoelectric element (3) which is an element for detecting a change in air pressure, a detection section including electrodes (31) (32) at both ends thereof, and Impedance conversion circuit (4) composed of leak resistance (33) and FET (field effect transistor) (34) connected in parallel
Consists of. The impedance conversion circuit (4) lowers the internal resistance of the piezoelectric element (3).

In the air pressure sensor (11), first, the piezoelectric element (3) is actuated by the fluctuation of the air pressure, and the electrical signal is taken out from the air pressure sensor (11) by the actuation.
However, since this electrical signal is transmitted from the piezoelectric element (3), which has a very large internal resistance, and the output cannot be extracted as it is, the impedance conversion circuit (4) extracts a current and the conversion circuit (18) extracts it. The voltage is converted into a predetermined voltage and then applied to the comparator.

Thereafter, the electric signal reaches the AND circuit (17) via the comparators (33) (35) and the signal holding means (16) and is used for determining the presence or absence of an intruder. Next, the operation of the alarm device incorporating the air pressure sensor (11) will be described in detail.
When the intruder opens the door, the air pressure in the room drops, and the air pressure sensor (11) senses this pressure drop, and the voltage output accompanying this is generated in the conversion circuit (18), and the output has a low reference voltage. It is applied to the first comparator (33).

The applied output becomes even lower than the low reference voltage determined by the reference voltage setting device (20) of the first comparator (33), and a signal is output from the first comparator (33). This is held by the signal holding means (16) for a certain period of time. Next, when an air pressure increase state following the air pressure decrease occurs due to the air vibration generated in the room when the door is opened, the output of the air pressure sensor (11) corresponding to the air pressure increase state is changed to the second via the conversion circuit (18).
It is detected by the comparator (35) and a signal is output from the second comparator (35).

Then, the signal of the second comparator (35) and the signal of the reference voltage setting device (20) are both applied to the AND circuit (17), and a detection signal is output from the AND circuit (17). It
Thus, in the signal processing device (14) of the present invention, the output of the air pressure sensor (11) passes through the comparators (33) (35) and the AND circuit (17).
Applied to the AND circuit (17), the detection signal is not output unless the output signal consisting of a pair of high and low pulses is applied from the air pressure sensor (11). ..

Therefore, it is possible to prevent malfunction of the alarm device due to transient operation of the air pressure sensor (11) such as temperature change in the room. In the second embodiment of the present invention, the microcomputer performs the operation of the signal processing device (14) described above, and FIG. 2 shows the procedure thereof. First to judge the output from the air pressure sensor (11)
If there is an output from the comparator (33) (comparator that detects a decrease in air pressure), the process proceeds to the next step, and if there is no output, the operation for determining the presence or absence of the output is repeated.

Next, it is determined whether or not there is an output from the second comparator (35), and if there is an output, a detection signal is output and the alarm device is activated. On the other hand, when there is no output, the air pressure sensor (1
A timer or the like determines whether or not a certain time has elapsed since the output from 1) was applied to this microcomputer. Until the time elapses, the presence or absence of the output from the second comparator (35) is determined, and the operation described above is performed according to the presence or absence of the output.

In this embodiment, the functional unit in the microcomputer for monitoring the signal of the second comparator (35) for a certain period of time when the signal of the first comparator (33) is present is technically described above. It corresponds to the signal holding means (16) described in the means. When the time elapses without outputting the detection signal, the process is repeated from the first process again (reset state).

By performing such signal processing,
Pneumatic sensor by hardware in Example 1 (11)
The signal processing of can be realized by software. In the third embodiment shown in FIG. 3, the output of the first comparator (33) is a first mono-multivibrator (hereinafter abbreviated as a first MM) (4
3) and the output of the second comparator (35) is applied to a second mono-multivibrator (hereinafter abbreviated as second MM) (4
5), and the first MM (43) corresponds to the first signal holding means (23) described in the technical means of claim 2.

The second MM (45) corresponds to the second signal holding means (25) described in the technical means of claim 2.
The set time of the first MM (43) and the second MM (45) is the same as the air pressure sensor (1) when the door for opening and closing the room is opened.
A little longer than the time interval of a pair of high and low signals resulting from (1) (
For example, it is set to about 3 seconds.

In this device, when a pair of high and low signals generated when the door is opened is output from the air pressure sensor (11), a signal higher than the output of the air pressure sensor (11) when there is no change in the air pressure in the room is the air pressure. When the sensor (11) first generates the signal, the second signal is detected by the second comparator (35). Then, the detection signal is held in the second MM (45) for a fixed time.

Next, when a signal indicating a "low" state is output from the air pressure sensor (11) following the above signal, this is detected by the opposite first comparator (33), and the 1MM
The signal (43) outputs a signal, the signals are applied to the two input terminals of the AND circuit (17), and the AND circuit (17) outputs an alarm signal. On the other hand, when the door is opened, conversely to the above, first, the signal indicating the "low" state is output from the air pressure sensor (11), and then the signal indicating the "high" state is output. The signal indicating the state is detected by the first comparator (33), and the detected signal is held by the first MM (43) for a fixed time.

When the signal indicating the latter "high" state is output from the air pressure sensor (11) and detected by the second comparator (35), the second MM (45) holding the detection signal.
And the signal of the first MM (43) are both AND circuits (17)
And an alarm output signal is output from the AND circuit (17). As described above, according to the third embodiment, regardless of whether the first signal generated when the door is opened is high or low,
An alarm output signal is generated, and it is possible to deal with doors of either outward or inward opening type.

In the third embodiment, the signal processing device is constructed by wiring the electronic parts, but it may be processed by a microcomputer. That is, the first comparator (33) and the second comparator
Monitor the output of (35), and if there is output from either one, monitor the output of the other comparator for a certain period of time, and when the output from this comparator occurs, output an alarm output signal to a specific port of the microcomputer. I will send it to you. (See Figure 4).

[Brief description of drawings]

FIG. 1 is a circuit diagram of an air pressure sensor for an alarm device and a signal processing device thereof according to a first embodiment.

FIG. 2 is a flowchart of a signal processing device of an air pressure sensor for an alarm device according to a second embodiment.

FIG. 3 is a circuit diagram of an air pressure sensor for an alarm device and a signal processing device thereof according to a third embodiment.

FIG. 4 is a flowchart in the case where the third embodiment is processed by a microcomputer.

FIG. 5 Conventional example

[Explanation of symbols]

 (11) ・ ・ ・ Air pressure sensor (13) ・ ・ ・ First detector (14) ・ ・ ・ Signal processing device (15) ・ ・ ・ Second detector (16) ・ ・ ・ Signal holding means (17) ・.... AND circuit (23) ... First signal holding means (25) ... Second signal holding means

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[Procedure amendment]

[Submission date] January 17, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (2)

[Claims] 1. A signal processing device for an air pressure sensor for an alarm device, which outputs an output signal by comparing an output of an air pressure sensor (11) with a reference value, the air pressure sensor (11) according to opening of an entrance / exit door to a room. Of the pair of high and low signals generated from the first detector (13), a second detector (15) for detecting the subsequent signal, and the first detector (13). Signal holding means (16) for holding the detection signal of (4) for a certain period of time, and an alarm output signal which is output only when the output from the signal holding means (16) and the detection signal of the second detector (15) are present. A signal processing device for an air pressure sensor for an alarm device provided with a circuit (17). 2. A signal processing device for an air pressure sensor for an alarm device, which outputs an output signal by comparing an output of the air pressure sensor (11) with a reference value, and the air pressure sensor (11) according to opening of a door for entering and exiting a room. A first detector (53) for detecting a high signal of a pair of high and low signals generated from the above, a second detector (55) for detecting a low signal, and a detection signal of the first detector (53). First signal holding means (23) for holding for a fixed time and the second detector (55)
Signal holding means (25) for holding the detection signal of
And an alarm device air pressure sensor provided with an AND circuit (17) which outputs an alarm output signal only when the first and second signal holding means (23) (25) hold the detection signal. Signal processing device.