GB2254174A

GB2254174A - Abnormal condition detecting unit and security alarm system using the same

Info

Publication number: GB2254174A
Application number: GB9204085A
Authority: GB
Inventors: Nobuyuki Akiyama
Original assignee: Nittan Co Ltd
Current assignee: Nittan Co Ltd
Priority date: 1991-03-25
Filing date: 1992-02-26
Publication date: 1992-09-30
Anticipated expiration: 2012-02-26
Also published as: JP2816606B2; GB9204085D0; GB2254174B; JPH04295991A

Abstract

When a detector 2 detects an abnormality (e.g. a fire), the voltage on the line Ln, is changed. When a voltage detecting and processing circuit 8 detects that the voltage on the line has been changed by the activation of its own detector, a first sound is outputted from a speaker 11. When the line voltage is changed by the activation of the detector of another detecting unit which is connected in parallel to the same line, a second sound is outputted. Each line L1, Ln covers a respective region (A1, An fig 1, not shown). If a fire is detected in region (A1), a central monitoring and control apparatus (1) changes the voltage on the line (Ln) to cause the speakers (11) of all of the fire detecting units (T1, Tj) on the line (Ln) to output a third sound. Thus, the first sound indicates that a fire is close by, the second sound indicates that there is a fire somewhere else in that region and the third sound indicates that there is a fire in a different region. The central monitoring and control apparatus includes an emergency broadcasting device (24, fig. 3, not shown) to provide a voice signal to the speakers via the communication lines L1, Ln. <IMAGE>

Description

ABNORMAL CONDITION DETECTING UNIT AND SECURITY ALARM SYSTEM USING THE SAME The present invention relates to a unit for detecting an abnormal condition such as fire, smoke, leakage of fluid, intrusion and the like and a security alarm system using the same.

A so-called P type fire alarm apparatus has been known in which at least one fire detector is connected to a regional line extending from a central monitoring and control device to each monitoring region. In a prior art fire alarm system including this type of fire alarm apparatus, a regional bell is provided for each regional line. When an alarm detector in a region detects an abnormal condition and notifies the central monitoring and control apparatus of it, the central monitoring and control apparatus is adapted to activate the regional bell in this region via the corresponding regional line.

In the case where an emergency broadcasting device in addition to the fire alarm apparatus is provided in the fire alarm system, emergency broadcasting can be performed for each region.

Thus, when a fire alarm detector in one region detects an abnormal condition and informs the central monitoring and control apparatus of it, the regional bell in this region is activated by the central monitoring and control apparatus, and a person who hears this ringing can notice that an abnormality occurs in this region. However, the prior art fire alarm system encounters a problem in that a person cannot precisely identify the place where the abnormality occurs in this region. Furthermore, unless a regional bell in the other region is activated in association therewith, a person in the other region cannot notice the occurrence of any abnormality. Conversely, if a regional bell in the other region is activated in association therewith, it will cause confusion because a person in the other region mistakenly thinks that an abnormality has occurred in his region.

On the other hand, in the case where the fire alarm system has an emergency broadcasting device, the person in the other region can notice the details of the abnormality. However, many lines independent of the regional lines are needed to send emergency broadcasting signals from the central monitoring and control apparatus to the respective regions, which makes the system configuration very complicated.

According to a first aspect of the present invention, there is provided an abnormal condition detecting unit connectable to a communication line, comprising: a sensor for detecting an abnormal condition; and audio means connected to said sensor; said abnormal condition detecting unit being arranged to change the voltage on the line when said sensor detects the occurrence of an abnormal condition, and said audio means being arranged to output different sounds depending upon whether the change in voltage on the line which is detected by said audio means has or has not been caused by said sensor.

According to a second aspect of the present invention, there is provided an abnormal condition detecting unit connectable to a communication line, comprising: a sensor for detecting an abnormal condition; and audio means connected to said sensor for outputting a specific sound when said audio means detects a change in voltage on the line and/or for outputting an emergency broadcasting sound when it receives an emergency broadcasting voice signal on the line.

According to a third aspect of the present invention, there is provided a security alarm system, comprising: a central monitoring and control apparatus; a plurality of communication lines extendable from said central monitoring and control apparatus to respective regions; and a plurality of abnormal condition detecting units according to the first or second aspects of the present invention and connectable to said lines.

Embodiments of the present invention provide an abnormal condition detecting unit and a security alarm system using the same in which varied alarm control can be achieved depending upon the place and the region of the abnormality, without requiring a complicated system configuration.

In an embodiment, the audio means outputs a sound corresponding to a level V1 when the line voltage has been changed by the activation of its own detector and outputs a sound corresponding to a level V2 when the line voltage has been changed by the activation of a detector of another detecting unit which is connected in parallel to the same line.

Also, when the line voltage has been changed by the central monitoring and control apparatus, the audio means of the detecting unit may detect the change in voltage and output a sound corresponding to a level V3. Furthermore, when an emergency broadcasting voice signal is sent along the line from the central monitoring and control apparatus, the audio unit may receive it and output an emergency broadcasting sound.

The central monitoring and control apparatus may have an emergency broadcasting device for outputting a sound signal to the audio means of each detecting unit via the lines.

For example, when the detector of one of a plurality of abnormal condition detecting units which are connected to one of the lines becomes active, the detecting unit including the sensor which is active now outputs a sound corresponding to the level V1 and each of the other detecting unit(s) connected to the same line outputs a sound corresponding to the level V2. The voltage on each of the other lines is changed, and the detecting units which are connected to those lines output a sound corresponding to, for example, the level V3 or output an emergency sound by detecting an emergency broadcasting voice signal sent through those lines.

The invention will now be described by way of a non-limiting embodiment with reference to the accompanying drawings, in which: Fig. 1 is a block diagram showing an embodiment of a security alarm system of the present invention; Fig. 2 is a block diagram showing an abnormal condition detecting unit in the security alarm system; and Fig. 3 is a block diagram showing a central monitoring and control apparatus in the security alarm system.

Referring now to Fig. 1, there is illustrated a block diagram showing an embodiment of a security alarm system of the present invention. The alarm system of this embodiment includes regional lines Ml to Mn which extend from a central monitoring and control apparatus 1 to monitoring regions Al to An, respectively.

To each of the regional lines M1 to Mn is connected at least one abnormal condition detecting unit. For example, a plurality of detecting units S1 to Si are connected in parallel to the regional line M1, and a plurality of detecting units T1 to Tj are connected in parallel to the regional line Mn. In other words, assuming that the security alarm system is installed in, for example, a building having n floors and the monitoring region Al is the whole of the first floor of this building and the monitoring region An is the whole of the nth floor of this building, each of the detecting units S1 to Si which are connected to the regional line M1 would be installed in the monitoring region Al (i.e. at a given place of the first floor) and each of the detecting unit T1 to Tj would be installed in the monitoring region An (i.e. at a given place on the nth floor).

Each regional line M1 to Mn comprises a pair of lines. For example, the regional line M1 comprises a pair of lines (L1, CO) and the regional line Mn comprises a pair of lines (Ln, CO). The line CO is maintained at ground level, while a given voltage which is not zero is applied to the lines L1 to Ln.

Referring now to Fig. 2, there is illustrated a block diagram showing one of the detecting units S1 to Si or T1 to Tj.

For simplicity of description of the embodiment, it is assumed that all detecting units are identical to each other in structure. The detecting unit, for example, T1 comprises a detector 2 and an audio unit 3 which is connected with the detector 2.

The detector 2 comprises a fire sensor 4 for sensing an abnormal condition such as smoke or heat, a thyristor 5 which is brought into a conductive state when the abnormal condition is detected by the fire sensor 4, and diodes 6 and 7. The audio unit 3 comprises a voltage detecting and processing circuit 8 which outputs one of the voltage detection signals, each having a predetermined level V1, V2 or V3, an audio signal generator 9 for generating an audio signal corresponding to the level of the detection signal from the voltage detecting and processing circuit 8, an amplifier circuit 10 for amplifying the audio signal from the audio signal generator 9, a speaker 11 for converting the audio signal which has been amplified by the amplifier circuit 10 into actual sound, a power supply 12, an impedance element 13 which exhibits high and low impedances for a.c. and d.c. signals, respectively, and a capacitive element (capacitor) 14 which allows only an a.c. signal to pass from line Ln to the amplifier circuit 10.

The audio unit 3 is connected with the lines Ln and CO at the terminals B1 and B2, respectively. The audio unit 3 is also connected with the alarm detector 2 by connecting the terminals B4 and B5 of the audio unit 3 with the terminals B6 and B7 of the detector 2 respectively. That is, the impedance element 13 of the audio unit 3 is connected with the diode 6 of the detector 2 via the terminals B5 and B7. The voltage detecting and processing circuit 8 is connected with the diode 7 of the detector 2 via the terminals B4 and B6. When the detector 2 of the detecting unit T1 detects an abnormal condition and becomes active to bring the thyristor 5 into a conductive state, a current flows from the line Ln through the impedance element 13, the diode 6, and the thyristor 5 to the line CO.At this time, the voltage of the line Ln is lowered.

The voltage detecting and processing circuit 8 of the audio unit 3 determines whether or not the detector 2 is active on the basis of the voltage on the terminal B4 , and also determines whether or not the voltage of the line Ln has changed on the basis of the voltage on the terminal B1.

When the voltage on the line Ln is lowered to less than a given value while detector 2 is active, the voltage detecting and processing circuit 8 outputs a voltage detection signal having a level V1 representing that an abnormal condition occurs in the position where the detecting unit T1 is installed. While when the voltage on the line Ln is lowered to less than a given value in such a condition that the detector 2 is not active, the voltage detecting and processing circuit 8 determines that the change in voltage on the line Ln is caused by another detecting unit (e.g. Tj) which is connected to the same line Ln, and outputs a voltage detection signal having a level V2 representing that an abnormality occurs in the other detecting unit of the same region.While, when the voltage on the line Ln is changed to a predetermined value other than the above two cases, the voltage detecting and processing circuit 8 determines that a change in the voltage on the line Ln is caused by the central monitoring and control apparatus, and outputs a voltage detection signal having a level V3 representing that an instruction is issued from the central monitoring and control apparatus 1.

Referring to Fig. 3, there is illustrated a block diagram showing the central monitoring and control apparatus 1. The central monitoring and control apparatus 1 comprises a power supply 20, current and voltage control units CTi to CTn which are provided for the regional lines M1 to Mn, respectively, for detecting and controlling the current flow through each of the regional lines and the voltage thereon, a signal processing unit 21 for processing and controlling signals related with a fire alarm, an operational input unit 22 for instructing the operation of the signal processing unit 21 and an alarm display 23 for displaying abnormalities. In the example of Fig. 3, the central monitoring and control apparatus 1 further includes an emergency broadcasting device 24 and a microphone 25 for broadcasting.

The power supply 20 outputs voltages such as voltages El and E2. In this case, the voltage El is normally applied to each of the lines L1 to Ln while the line CO is maintained at ground level "0". The current and voltage control units CTi to CTn are identical to each other in structure.For example, the current and voltage control unit CTl comprises a current detecting circuit 30 for detecting the current flow through the line L1 when the voltage El is being applied to the line L1, a switching circuit 31 for applying the voltage E2 from the power supply 20 to the line L1 in response to a signal SW from the signal processing unit 21, and a signal transmitter 32 for sending an audio signal for emergency broadcasting from the emergency broadcasting device 24 to the line L1.

Operation of the thus formed fire alarm system will now be described. The central monitoring and control apparatus 1 normally opens the switching circuit 31 for each of the lines L1 to Ln so that the voltage El (for example, 24 volts) is applied to each of the lines L1 to Ln, respectively.

Under such a condition, if the detector 2 of the detecting unit T1 in the region An detects an abnormality such as fire and becomes active, a current flows from the line Ln through the fire detecting unit T1 to the line CO. When a current flows between the lines Ln and CO through the detecting unit T1, the voltage El on the line L1 is lowered from 24 volts, for example, to a level not higher than 6 volts.

Thus, the voltage detecting and processing circuit 8 of the detecting unit T1 can detect that the voltage on the line Ln becomes 6 volts or less and that its own fire detector 2 is active, which results in applying a voltage detection signal having the level V1 to the audio signal generator 9 of the detecting unit T1. The voltage detecting and processing circuit 8 of the other detecting unit (e.g. Tj) in this region An can also detect that the voltage of the line Ln is not higher than 6 volts, and that its own detector 2 is not active, which results in applying a voltage detection signal having the level V2 to the audio signal generator 9 of the other detecting unit (e.g. Tj).

As a result of this, in the detecting unit T1 which actually detects the abnormality such as fire in the region An, a specific sound corresponding to the voltage detection signal having the level V1 is output from the speaker 11 via the audio signal generator 9 and the amplifier circuit 10. In the other detecting unit (ex. Tj) which has not detected the abnormality such as fire in the region An, a sound corresponding to the level V2, which is different from the sound output from the detecting unit T1 is output from the speaker 11 via the audio signal generator 9 and the amplifier circuit 10.

This enables a person who is in the vicinity of the fire detecting unit T1 in the region An to notice the occurrence of the abnormality such as fire near him or her by hearing the sound corresponding to the level V1. Also, a person who is not in the vicinity of the fire detecting unit T1 can notice that the abnormality such as fire occurs in this region by hearing any one of the sounds output from all of the detecting units in this region An, but can also notice that the abnormality does not occur near him or her by hearing the sound corresponding to the level V2 which differs from the level V1. In brief, the security alarm system of the present invention enables a person or persons to notice where the abnormality occurs in the same region by outputting sounds corresponding to two levels V1 and V2.

When the detector 2 of the detecting unit T1 in the region An is active to cause current flow through Ln, the current detecting circuit 30 of the current and voltage control unit CTn in the central monitoring and control apparatus 1 detects this current and then informs the signal processing unit 21 of the detection of the current. When the current is detected, the signal processing unit 21 determines that an abnormality such as fire occurs in the region An and then drives the alarm display 23 to display an abnormality.Simultaneously, in order to inform the regions other than the region An of the occurrence of this abnormality, the signal processing unit 21 sends a signal SW to the current and voltage control units CTl and so on correspondingly provided for the other regional lines M1 and so on in order to close the switching circuit 31 for applying the voltage E2 (for example, 28 volts) from the power supply 20 to the lines L1 and so on. This causes the voltage detecting and processing circuit 8 of the detecting units (e.g. S1) installed in the regions (e.g.Al) other than the region An where the abnormality occurs to detect an increase in voltage on the line L1, from 24 to 28 volts, and to apply a voltage detection signal having a level V3 to the audio signal generator 9 so that a specific sound corresponding to the level V3 is output from the speaker 11.

As a result, a person or persons in the regions other than the region An can notice the occurrence of the abnormality, but can also notice that the abnormality does not occur in their regions since the sound output in this region does not correspond to the levels V1 and V2.

If a voice synthesizing device is used as the audio signal generator 9 for outputting an imitation sound or a synthesized voice from the speaker 11, the alarm system can more positively warn the persons of the occurrence of the abnormality. For example, the alarm system can positively inform the persons in the region where the abnormality occurs by announcing "Fire! Please check!" and "Fire near here! Evacuate!" respectively corresponding to the levels V1 and V2, following bell ringing.

If special music is broadcast as the sound corresponding to the level V3, only personnel aware of the significance of the special music will notice the occurrence of the abnormality in the other region and other people will not be anxious as they will not be aware that there is an alarm.

In the present embodiment, the central monitoring and control apparatus 1 also has a built-in emergency broadcasting device 24. When an operator of the central monitoring and control apparatus 1 inputs an emergency broadcasting message through the microphone 25, a message signal will be sent to the detecting unit installed in each of the regions Al to An via the respective lines L1 to Ln. When the detecting unit (e.g. T1) shown in Fig. 2 receives the message signal via the line Ln, it directly transmits this message signal to the amplifier circuit 10 via the capacitive element 14. This enables the speaker 11 of the detecting unit T1 to output the emergency broadcasting message which was input from the microphone 25 by the operator of the control monitoring and control apparatus 1.

In the present embodiment, varied control of the audio output can be performed according to the levels V1, V2 and V3, and this is achieved by.using only conventional regional lines M1 to Mn, one line for each of the regions Al to An without the need for providing additional lines. Furthermore, specific lines for sending emergency broadcasting signals to each region are not needed because the above mentioned regional lines can also be used for this purpose. Accordingly, the structure of the alarm system is not complicated.

In the example described above, the central monitoring and control apparatus 1 uses the voltage E2 (for example, 28V) which is higher than the normal voltage El (for example, 24V). Instead of this, it is also possible to use a voltage E2 (for example 20V) lower than the normal voltage El. In this case, the voltage detecting and processing circuit of the detecting unit outputs the voltage detection signal having the level V3 in response to a decrease (ex. about 4 volts) in voltage.

As shown in Fig. 2, the power supply 12 of the fire detecting unit may be connected to the line Ln via a resistor 41 and a diode 40. In such a case, the power supply 12 of the detecting unit can be charged with electric power via the line Ln from the power supply 20 of the central monitoring and control apparatus 1. Provision of the diode 40 prevents the power from being discharged from the power supply 12 to the line Ln when the potential of the line Ln falls below the potential of the power supply 12.

As described above, since the detecting unit of the present invention is arranged to output different sounds depending upon whether or not its own fire detector is active when the change in voltage on the line is detected, a person in the same region can identify the place where the abnormality occurs as well es the occurrence of the abnormality.

In the case where the detecting unit of the present invention is arranged to output a specific sound when it detects the change in voltage on the line and to output an emergency broadcasting sound when it receives an emergency broadcasting voice signal sent along the line, the detecting unit is capable of informing a person in the other regions of the occurrence of an abnormality and is capable of informing or broadcasting that the abnormality does not occur in his region.

In a security alarm system in which at least one detecting unit having a structure as described above is connected to a regional line extending from the central monitoring and control apparatus to each region, varied alarm control can be carried out depending upon the place and the region without complicating the system configuration.

Furthermore, in the case where the central monitoring and control apparatus has a built-in emergency broadcasting device for outputting a voice signal which is input to the audio unit of the fire detecting unit via the regional line, emergency broadcasting can be performed without providing additional emergency broadcasting lines.

Having described the present invention with reference to one embodiment of an abnormal condition detecting unit and a security alarm system, it will be understood by those skilled in the art that variations and modifications may be made thereto without departing from the present invention.

For example, the present invention can be used to detect and provide an alarm in response to an abnormality such as intrusion of an unauthorised person or leaking of a fluid other than heat or smoke.

Claims

1. An abnormal condition detecting unit connectable to a communication line, comprising: a sensor for detecting an abnormal condition; and audio means connected to said sensor; said abnormal condition detecting unit being arranged to change the voltage on the line when said sensor detects the occurrence of an abnormal condition, and said audio means being arranged to output different sounds depending upon whether the change in voltage on the line which is detected by said audio means has or has not been caused by said sensor.

2. An abnormal condition detecting unit connectable to a communication line, comprising: a sensor for detecting an abnormal condition; and audio means connected to said sensor for outputting a specific sound when said audio means detects a change in voltage on the line and/or for outputting an emergency broadcasting sound when it receives an emergency broadcasting voice signal on the line.

3. A security alarm system, comprising: a central monitoring and control apparatus; a plurality of communication lines extendable from said central monitoring and control apparatus to respective regions; and a plurality of abnormal condition detecting units according to claim 1 or 2 and connectable to said lines.

4. A security alarm system according to claim 3, wherein said central monitoring and control apparatus has an emergency broadcasting device for outputting a sound signal to said audio means of each detecting unit via said lines.

5. A security alarm system according to claim 3 or 4, wherein said lines extend between said central monitoring and control apparatus and said regions and said detecting units are connected to said lines.

A A security alarm system according to claim 5, wherein each line has at least two of said detecting units connected thereto.

7. An abnormal condition detecting unit substantially as herein described with reference to, or with reference to and as illustrated in, Figures 1 and 2 of the accompanying drawings.

8. A security alarm system substantially as herein described with reference to, or with reference to and as illustrated in, Figures 1 to 3 of the accompanying drawings.

9. All novel features and combinations thereof.