CA1194573A - Method and apparatus for identifying the location of a change in state of a part of an electrical circuit - Google Patents
Method and apparatus for identifying the location of a change in state of a part of an electrical circuitInfo
- Publication number
- CA1194573A CA1194573A CA000408770A CA408770A CA1194573A CA 1194573 A CA1194573 A CA 1194573A CA 000408770 A CA000408770 A CA 000408770A CA 408770 A CA408770 A CA 408770A CA 1194573 A CA1194573 A CA 1194573A
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- Prior art keywords
- circuit
- state
- devices
- bistate
- recited
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
- G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
- G08B25/018—Sensor coding by detecting magnitude of an electrical parameter, e.g. resistance
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
- G08B29/02—Monitoring continuously signalling or alarm systems
- G08B29/06—Monitoring of the line circuits, e.g. signalling of line faults
- G08B29/08—Signalling of tampering with the line circuit
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Alarm Systems (AREA)
Abstract
Abstract of the invention An electrical circuit arrangement including a plurality of bistate devices such as vibration detection devices connected therein, each occupying a particular position in the circuit, and each having a resistor associated therewith, such that a predetermined value of resistance normally prevails and the value is changed when any device changes state, comparison means for comparing a parameter such as the current in the circuit with a reference parameter to indicate the identity of any device which has changed state and the position in the circuit of any changed-state device.
Description
BACKGROUND TO THE INVENTION
.
Field of the Invention This invention relates to a met;hod and apparatus for identifying the location of a change in state of a port;on of an electrical circuit and particularly, but not exclusively relates to a method and apparatus for identifying which part of a protective circuit has been caused to change state.
In protective circuits used ;n intruder protection systems and fire and bandit warning systems including intruder detectian and warning devices and fire and bandît warning alarms and detectors capable of provid;ng a warning indication of any abnormal occurrence such as the.entry of heat.smoke or fire by a change of state of a device, it has not previously been possible, where a number of detector devices are included in the protective circuit,to readily identify which particular detector device has been caused to change state, without installing expensive control apparatus, or wiring each detector device separately to ~he control apparatus.
Objects of the invention One object of the invention is to provide a method and apparatus for identifying the location ;n an electrical circuit of a part of the circuit which has been caused to change state.
Another object of the invention is to provide a method and apparatus for identifying the location in an electrical circuit of a bi-state device which has been caused to change state.
A further object of the invention is to provide a method and apparatus for identifying the location of an intruder detecting device wired in series with a plurality of devices in an electrical protective or security circuit, when thP
said device has changed state.
A still further object of the invention is to provide a method and apparatus for locating a vibration sensing device in an electrical security circuit when the device has changed state.
A further object of the invention is to locate a reed switch of a plurality of reed switches connected in series in a security circuit when the said reed switch has changed state.
It is a further object of the invention to provide a method and apparatus for monitoring an electrical security circuit when one of the devices in the c;rcuit is faulty or has failed.
A still further object of the invention is to provide a method and apparatus to identiFy and locate the position of tampering in an electrical security circuit if the circuit has been tampered with.
Summary of the invention According to one aspect of the invention, there is provided an electrical circuit arrangement including a plurality of bi-s~ate devices connected therein, each occupying a particular position in the circuit and each having an impedance element associated therèwith such that a pre-determined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from 5~73 said one state to a second s~ate, and means for compariny a parameter of the circuit with a reference parameter to provide an indication of the ;dentify of any bi-state device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit.
Not only is it advan~ageous to identify the particular location where a device of the circuit has changed state~
but it would also be an advantage not only to identify the changed-state device, but also to identify a failed or faulty device and to continue to utilise the circu-it containing the failed or faulty device.
According to another aspect of the invention there is provided an electrical circuit arrangement including a plurality of bi-state devices connected therein, each occupying a particular position in the circuit and each having an impedance element associated therewith such that a predetermined value of impedance prevails in the circuit when all said bi--state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from said one state to a second state, and means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bistate device which has changed from said one state to sa;d second state and to ident;fy the pos;-~ion of said changed-state device in the circuitl said b;state devices being included in a multi-terminal network, and monitoring means operable in accordance with a plurality of modes for monitoring said bistate dev;ces across different combinations of pairs of terminals of said network, to allow not only the part;cular device which has changed state to be identified and the position thereof to be located, but to allow devices which have failed or are faulty to be identified and the circuit, to be utilised irrespective of the failure of~ or fault in any such device.
The impedance elements may be resistors or diodes, zener diodes, transistors, or other such semiconductors.
In one embodiment of the invention, the electrical circuit includes a plurality of bistate devices and associated resistors, means for applying an e.m.f. across the circuit, further means for measuring the current flowing through the circuit, and means for comparing the current in the circuit with a reference current to provide an indication of a change of s~ate of any of the bistate devices.
The ret`erence current is supplied v;a a scanning circuit to a comparator device and correspondence between the measured and reference current prov;des ;dent;fication of the particular bistate device which has changed state. A
warning relay and/or visual display may be provided to provide an audible or visual indication of the changed state device.
In another embodiment of the invention, the bistate devices are included in a protective circuit comprising a plurality of security detection devices, each detection device including a sensing device, an anti-tamper device and a resistor, housed within a single unit. The de~ection devices are connected in series, as are the anti-tamper devices, the conductor containing the former being connected with the conductor containing the latter hy said resistors. The above-mentioned conductors are provided with input terminals and a further pair of conductors are each provided with an input terminal the arrangement being such that the resistance of the circuit may be measured from either and thereof to provide an indication of any particular device which has changed state and to allow the circuit to continue in operation despite a falled device under the control of a multi mode m;croprocessor.
Advantages of the invention The advantages of the inventicn are many. One particula advantage is that i~ is possible to locate a part of an electrical circuit which has changed state~ Accordingly, a component which has changed state as a result of a change in its envircnment or a faulty component or component which has failed can readily easily be identified and corrective action as desired may be taken, or in the case of a failed component it may be replaced.
When the method and apparatus are used in a security circuit comprising a number of intruder detecting devices, the location of a device which has changed state as a result of, for example, detecting an intruder, can be immediately identif;ed even when the devices are wired in series.
Similarly, faulty or failed devices can be immediately identified.
A further advantage of the invention is that it permits intruder detecting devices or switches of a security circuit to be wired in series, while each individual device can s-till be identified. This leads to considerable simplicity of installation of the devices and also considerably reduces installation and w;ring costs.
A further advantage of the invention is that it permits the security circuit to be remotely monitored by, for example, a phone line or the like.
Additionallyg when the intruder devices are mounted on~
for example, doors or windows, if a memory is added to the circuit, the memory may be used to record and store the times at which the doors and windows were opened and closed. Indeed, the opening and closing of each door may be individually and separately monitored.
An additional advantage of the invention is that it permits the location of any bi-stable device to be located in an electrical circuit, whether or not the device is wired in series with other devices.
These and further advantages of the invention will be readily apparent from the following descriptions of some preferred embodiments thereof given by way oF example only with reference to the accompanying drawings.
- 1 o Brief description of the drawings Figure 1 is a circuit diagram of an electrical protective system incorporat;ing means for identifying the location of any part of the system undergoing a change in state, Figure 2 is a circuit diagram of another embodiment of the ;nvention, Figure 3 is a circuit diagram of a further embodiment of the invention, and Figure 4 is a circuit diagram of a still further embodiment of the invention.
De~ailed description of the inventian Referrlng initially to Figure 1, there is illustrated an electrical protective circuit employing a number of vibration sensitive devices arranged to change state in response to the detection of vibration in a structure or in part oF the structure such as in a window or door of a building and with which the vibration sensing device is associated. The protective c;rcuit designated A has a pair of input terminals 1, 1' to wh;ch a control circuit designated B is arranged to be connectedO A resistor Rl is connected across terminals 1, 1'~ for a purpose herein-after defined. The protective circuit includes six vibration detection devices 2 to 7 ;nclusive for detecting vibrations in a window~ door or other structure of a building, and may be similar to the de~ection devices referred to in British Patent Specification No. 2000377.
The vibration detection devices 2 to 7 are connected in series as shown and each device 2 to 7 has an associated resistor R2 to R7 respectively connected between an output terminal 8 of each device and an earthed line 9. Each device i5 provided with an input terminal 10 connected to the output terminal 8 of the next adjacent device such that the devices 2 to 7 are connected in series.
The arrangement is such that the resistance of the protective circuit A between the terminals 1, 1', varies in accordance with the particular vibration detection device which changes -~2-state. Each of the resistors Rl to R7 are preferably of 1 megaohm and the resistor Rl ;s connected across the terminals 1, 1', to provide a current path through the protective circuit3 should the vibration detection device ~ change state.
The control circuit B, includes controi apparatus 11 for identifying the location in the protective circuit A of any device ~ to 7 which unde~goes a change ;n sta~e. The control circuit B also includes control apparatus 12 for monitoring the frequency of vibrat;on of any of the vibration detection devices 2 to 7 and should the frequency be within certain predetermined lim~ts, the apparatus 12 effects energisation of a relay 21 of a visual or audible warning device (not shown) to provide an alarm indication.
Control apparatus 11 includes means (not shown~ for applying an e.m.f. typically 6 volts, across the input terminals 1, 1', of the protective circu-it A. A comparator 13 is provided with a pair of inputs, one of wh~ch is connected to protective circuit A and the other of which ~s connected to a reference circuit 14 via a bistable state device 15. The comparator 13 compares the current flowing through the protective circuit A with a re~Ference current generated by device 14 and which comprises a bank of resistors 16 corresponding to the resistors R2 to R7 of the protective circuit A.
The reference current is supplied via the scanning circuit 17 and bistable device 15 to one input of the comparator 13.
As the scanning circuit 17 scans the resistors 16, for correspondence between the current flowing ;n the protective circuit A and the instantaneous reference current, the particular vibration detection device which has changed state is identified by the control circuit 12.
The signal from the protective circuit A is passed from the scanning circuit 17 to a multiplex scanning unit 18 via respective integrator circuits 19 wh;ch provide a signal indicative of the frequency of the sign~l. If the signal is within certain predeterm;ned limits, the signal passes to the multiplex scanning unit 18 and an output signal therefrom initiates energisat;on of relay 21 and is supplied to the digital display device 20 such that a visual indication is provided of the particular vibration detection device 2 to 7 which has changed state.
When the vibration detection devices 2 to 7 arP in their quiescent state, current will flow through all the devices and the resistance measured across the input terminals 1, 1', will be:-Rl ~ R2 + R3 ~ R4 ~ R'; ~ R6 7 R~.R2-R3-R4-R5-R6- 7 Ifg for example, vibration detect;on device 5 begins to vibrate and interrupts the current flow through the protective circuit 1, the portion of the circuit A beyond device 5 is isolated and device 5 itself will be in an open ciircuit state.
Accordingly the resistance of the protective circuit A
monitored by the control circuit B is:-Rl + R2 + R3 + R4 .
Rl.R2.R3.R4 The resistance monitored will clearly indicate that it isvibration detection device 5 that has changed from a quiescent state ~o an open circuit state and the display device 20 will indicate in digital form, device 5.
In the embodiment of the invention illustrated in Figure 2, the protective citcuit A of Figure 1 is provided with, in ~15-addition to the vibration detection devices, a respective anti-tamper device, all housed w;thin one unit.
Thus, referring to Figure 2, five serîes-connected vibration detection devices are shown at 2, 3, 4, 5, 6, with the input terminals 1, 1', and the resistor Rl connected between lines 2B, 29 and the resistors R2, R3, R4, R5, R6 connected respectively between the output terminals of the devices 2 to 6 and the line 2~. In addition to the vibration detection devices 2 to 6, anti-tamper devices 30 to 34 are provided. The vibration detection devices
.
Field of the Invention This invention relates to a met;hod and apparatus for identifying the location of a change in state of a port;on of an electrical circuit and particularly, but not exclusively relates to a method and apparatus for identifying which part of a protective circuit has been caused to change state.
In protective circuits used ;n intruder protection systems and fire and bandit warning systems including intruder detectian and warning devices and fire and bandît warning alarms and detectors capable of provid;ng a warning indication of any abnormal occurrence such as the.entry of heat.smoke or fire by a change of state of a device, it has not previously been possible, where a number of detector devices are included in the protective circuit,to readily identify which particular detector device has been caused to change state, without installing expensive control apparatus, or wiring each detector device separately to ~he control apparatus.
Objects of the invention One object of the invention is to provide a method and apparatus for identifying the location ;n an electrical circuit of a part of the circuit which has been caused to change state.
Another object of the invention is to provide a method and apparatus for identifying the location in an electrical circuit of a bi-state device which has been caused to change state.
A further object of the invention is to provide a method and apparatus for identifying the location of an intruder detecting device wired in series with a plurality of devices in an electrical protective or security circuit, when thP
said device has changed state.
A still further object of the invention is to provide a method and apparatus for locating a vibration sensing device in an electrical security circuit when the device has changed state.
A further object of the invention is to locate a reed switch of a plurality of reed switches connected in series in a security circuit when the said reed switch has changed state.
It is a further object of the invention to provide a method and apparatus for monitoring an electrical security circuit when one of the devices in the c;rcuit is faulty or has failed.
A still further object of the invention is to provide a method and apparatus to identiFy and locate the position of tampering in an electrical security circuit if the circuit has been tampered with.
Summary of the invention According to one aspect of the invention, there is provided an electrical circuit arrangement including a plurality of bi-s~ate devices connected therein, each occupying a particular position in the circuit and each having an impedance element associated therèwith such that a pre-determined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from 5~73 said one state to a second s~ate, and means for compariny a parameter of the circuit with a reference parameter to provide an indication of the ;dentify of any bi-state device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit.
Not only is it advan~ageous to identify the particular location where a device of the circuit has changed state~
but it would also be an advantage not only to identify the changed-state device, but also to identify a failed or faulty device and to continue to utilise the circu-it containing the failed or faulty device.
According to another aspect of the invention there is provided an electrical circuit arrangement including a plurality of bi-state devices connected therein, each occupying a particular position in the circuit and each having an impedance element associated therewith such that a predetermined value of impedance prevails in the circuit when all said bi--state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from said one state to a second state, and means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bistate device which has changed from said one state to sa;d second state and to ident;fy the pos;-~ion of said changed-state device in the circuitl said b;state devices being included in a multi-terminal network, and monitoring means operable in accordance with a plurality of modes for monitoring said bistate dev;ces across different combinations of pairs of terminals of said network, to allow not only the part;cular device which has changed state to be identified and the position thereof to be located, but to allow devices which have failed or are faulty to be identified and the circuit, to be utilised irrespective of the failure of~ or fault in any such device.
The impedance elements may be resistors or diodes, zener diodes, transistors, or other such semiconductors.
In one embodiment of the invention, the electrical circuit includes a plurality of bistate devices and associated resistors, means for applying an e.m.f. across the circuit, further means for measuring the current flowing through the circuit, and means for comparing the current in the circuit with a reference current to provide an indication of a change of s~ate of any of the bistate devices.
The ret`erence current is supplied v;a a scanning circuit to a comparator device and correspondence between the measured and reference current prov;des ;dent;fication of the particular bistate device which has changed state. A
warning relay and/or visual display may be provided to provide an audible or visual indication of the changed state device.
In another embodiment of the invention, the bistate devices are included in a protective circuit comprising a plurality of security detection devices, each detection device including a sensing device, an anti-tamper device and a resistor, housed within a single unit. The de~ection devices are connected in series, as are the anti-tamper devices, the conductor containing the former being connected with the conductor containing the latter hy said resistors. The above-mentioned conductors are provided with input terminals and a further pair of conductors are each provided with an input terminal the arrangement being such that the resistance of the circuit may be measured from either and thereof to provide an indication of any particular device which has changed state and to allow the circuit to continue in operation despite a falled device under the control of a multi mode m;croprocessor.
Advantages of the invention The advantages of the inventicn are many. One particula advantage is that i~ is possible to locate a part of an electrical circuit which has changed state~ Accordingly, a component which has changed state as a result of a change in its envircnment or a faulty component or component which has failed can readily easily be identified and corrective action as desired may be taken, or in the case of a failed component it may be replaced.
When the method and apparatus are used in a security circuit comprising a number of intruder detecting devices, the location of a device which has changed state as a result of, for example, detecting an intruder, can be immediately identif;ed even when the devices are wired in series.
Similarly, faulty or failed devices can be immediately identified.
A further advantage of the invention is that it permits intruder detecting devices or switches of a security circuit to be wired in series, while each individual device can s-till be identified. This leads to considerable simplicity of installation of the devices and also considerably reduces installation and w;ring costs.
A further advantage of the invention is that it permits the security circuit to be remotely monitored by, for example, a phone line or the like.
Additionallyg when the intruder devices are mounted on~
for example, doors or windows, if a memory is added to the circuit, the memory may be used to record and store the times at which the doors and windows were opened and closed. Indeed, the opening and closing of each door may be individually and separately monitored.
An additional advantage of the invention is that it permits the location of any bi-stable device to be located in an electrical circuit, whether or not the device is wired in series with other devices.
These and further advantages of the invention will be readily apparent from the following descriptions of some preferred embodiments thereof given by way oF example only with reference to the accompanying drawings.
- 1 o Brief description of the drawings Figure 1 is a circuit diagram of an electrical protective system incorporat;ing means for identifying the location of any part of the system undergoing a change in state, Figure 2 is a circuit diagram of another embodiment of the ;nvention, Figure 3 is a circuit diagram of a further embodiment of the invention, and Figure 4 is a circuit diagram of a still further embodiment of the invention.
De~ailed description of the inventian Referrlng initially to Figure 1, there is illustrated an electrical protective circuit employing a number of vibration sensitive devices arranged to change state in response to the detection of vibration in a structure or in part oF the structure such as in a window or door of a building and with which the vibration sensing device is associated. The protective c;rcuit designated A has a pair of input terminals 1, 1' to wh;ch a control circuit designated B is arranged to be connectedO A resistor Rl is connected across terminals 1, 1'~ for a purpose herein-after defined. The protective circuit includes six vibration detection devices 2 to 7 ;nclusive for detecting vibrations in a window~ door or other structure of a building, and may be similar to the de~ection devices referred to in British Patent Specification No. 2000377.
The vibration detection devices 2 to 7 are connected in series as shown and each device 2 to 7 has an associated resistor R2 to R7 respectively connected between an output terminal 8 of each device and an earthed line 9. Each device i5 provided with an input terminal 10 connected to the output terminal 8 of the next adjacent device such that the devices 2 to 7 are connected in series.
The arrangement is such that the resistance of the protective circuit A between the terminals 1, 1', varies in accordance with the particular vibration detection device which changes -~2-state. Each of the resistors Rl to R7 are preferably of 1 megaohm and the resistor Rl ;s connected across the terminals 1, 1', to provide a current path through the protective circuit3 should the vibration detection device ~ change state.
The control circuit B, includes controi apparatus 11 for identifying the location in the protective circuit A of any device ~ to 7 which unde~goes a change ;n sta~e. The control circuit B also includes control apparatus 12 for monitoring the frequency of vibrat;on of any of the vibration detection devices 2 to 7 and should the frequency be within certain predetermined lim~ts, the apparatus 12 effects energisation of a relay 21 of a visual or audible warning device (not shown) to provide an alarm indication.
Control apparatus 11 includes means (not shown~ for applying an e.m.f. typically 6 volts, across the input terminals 1, 1', of the protective circu-it A. A comparator 13 is provided with a pair of inputs, one of wh~ch is connected to protective circuit A and the other of which ~s connected to a reference circuit 14 via a bistable state device 15. The comparator 13 compares the current flowing through the protective circuit A with a re~Ference current generated by device 14 and which comprises a bank of resistors 16 corresponding to the resistors R2 to R7 of the protective circuit A.
The reference current is supplied via the scanning circuit 17 and bistable device 15 to one input of the comparator 13.
As the scanning circuit 17 scans the resistors 16, for correspondence between the current flowing ;n the protective circuit A and the instantaneous reference current, the particular vibration detection device which has changed state is identified by the control circuit 12.
The signal from the protective circuit A is passed from the scanning circuit 17 to a multiplex scanning unit 18 via respective integrator circuits 19 wh;ch provide a signal indicative of the frequency of the sign~l. If the signal is within certain predeterm;ned limits, the signal passes to the multiplex scanning unit 18 and an output signal therefrom initiates energisat;on of relay 21 and is supplied to the digital display device 20 such that a visual indication is provided of the particular vibration detection device 2 to 7 which has changed state.
When the vibration detection devices 2 to 7 arP in their quiescent state, current will flow through all the devices and the resistance measured across the input terminals 1, 1', will be:-Rl ~ R2 + R3 ~ R4 ~ R'; ~ R6 7 R~.R2-R3-R4-R5-R6- 7 Ifg for example, vibration detect;on device 5 begins to vibrate and interrupts the current flow through the protective circuit 1, the portion of the circuit A beyond device 5 is isolated and device 5 itself will be in an open ciircuit state.
Accordingly the resistance of the protective circuit A
monitored by the control circuit B is:-Rl + R2 + R3 + R4 .
Rl.R2.R3.R4 The resistance monitored will clearly indicate that it isvibration detection device 5 that has changed from a quiescent state ~o an open circuit state and the display device 20 will indicate in digital form, device 5.
In the embodiment of the invention illustrated in Figure 2, the protective citcuit A of Figure 1 is provided with, in ~15-addition to the vibration detection devices, a respective anti-tamper device, all housed w;thin one unit.
Thus, referring to Figure 2, five serîes-connected vibration detection devices are shown at 2, 3, 4, 5, 6, with the input terminals 1, 1', and the resistor Rl connected between lines 2B, 29 and the resistors R2, R3, R4, R5, R6 connected respectively between the output terminals of the devices 2 to 6 and the line 2~. In addition to the vibration detection devices 2 to 6, anti-tamper devices 30 to 34 are provided. The vibration detection devices
2 to 6 in addition to the antî-tamper devices 30 to 34 are connected in series~ and the input terminals 1, 1', are arranged such that an e.m.f. can be applied to the protective circuit A so that the resistance of the circuit can be measured.
In addition to the input terminals 1, 1', terminals 35, 36 are provided in loops 37, 38 conta;ning the vibration detectisn devices 2 to 6 and the anti-tamper devices 30 to 34 respectively. The additional terminals allow the resistance of the circuit to be measured from either end of the loops in the event of a change of state of one of the vibration detection devices 2 to 6 on one of the anti-tamper devices 30 to 34.
A microprocessor 39 is connected to the terminals 1~ 1';
and 35, 36, via a bilateral switch unit 40 and connections 41. The terminals 1, 1'; 35~ 36; are also connected via the bilateral switch unit 40, to four respective alanogue/
digital converters 42, the outputs of which are connected to respective terminals of the microprocessor 39. The analogue/digital converters 42 allow signals From the respective terminals 1, 1'; 35, 36; to be converted to digital signals for the microprocessor 39. A display panel (not shown) is connected to an output of the microprocessor 39, to provide a visual indication whether or not one of the vibration detection devices 2 to 6 or one of the anti-tamper devices 30 to 34 has changed state or is faulty such that the particular device which has changed state or is faulty, can be identified.
In operation, when it is required to lock-up a bu;lding for the night, the protective circuit is preset by placing each vibration detection device into a one state and the microprocessor 39, is set to a mode to deliver an e.m.F.
across the input terminals 1 9 11. If any one of the vibrat;on detection devices 2 to 6, or anti-tamper devices 30 to 34, is faulty, there will be a break in the continuity of the circuit and the microprocessor 39, will only measure the resistance of the circuit from Rl up to the resistance immediately before the faulty component, and thus the faulty component is immediately ;dentified.
If, for example, the faulty component is vibration cletection 4 then the microprocessor 39 by monitoring across the terminals 1, 1', will be able to monitor the vibration detect;on devices 2 and 3 and the anti-tamper devices 30 7 31. In order for the remaining devices 5, 6 and 33, 34, to be monitored, the microprocessor 39 is placed in a mode to monitor across the terminals 35, 1' as well as across the terminals 1, 1'.
By monitoring across the terminals 35, 1', it will be appreciated that the microprocessor will detect the resistors R6 and R5. Thus, should a fault occur in the devices 5 or 6 or 33, 34, this will be readily detected by the micro-processor.
The microprocessor can be placed in a further mode to monitor across terminals 1 and 36 such that should anti-tamper device 32 become faulty, the fault will be readilydetected and id~ntified.
The microprocessor may be placed in yet another mode to monitor across terminals 35~ 36 in addition to any of the modes already described. An advantage of monitoring across all the terminals is that a short circuit in any of the lines can also be readily identified and the position readily located.
Referring now to Figure 3 there is illustrated an electrical protective circuit according to a still further embodiment of the invention, this circuit is substantially similar to that described with reference to Figure 1 with the exception that the devices 2 to 7 in this embodiment of the invention are intruder detecting switches, provided by magnetic reed switches, which may be mounted on, for example, doors, windows or the like so that on opening of a door or window the circuit through the reed switch is opened. In this case the integrator circuits 19 are redundant. However, if it were desired to replace any of the devices 2 to 7 with vibration detection device this could readily be done and the integrator would then come into use.
The operation of this circuit is substantially similar to that described with reference to Figure 1. For examplP, when the reed switch 5 opens, the port;on of the circuit beyond the device 5 is isolated. Accordingly, the resistance of the protective circuit A mon;tored by the control circuit B is:-Rl ~ R2 + R3 + R4 Rl.R2.R3.R4.
Thus, the device on open circuit S will be immediatelyidentified and this information will be displayed on the digital display device 20. Additionally, the relay 21 will trigger an alarm.
Figure 4 illustrates an electrical protective circuit whic.h is again substantially similar to that of Figure 1.
In this case, the devicès 2 to 7 are vibra~ion detection devices and the resistors Rl to R7 are replaced by diodes Dl to D7. The diodes Dl to D7 perform a similar function to that of the resistors of Figure.
Although the invention has been described with particular reference to a protective circuit having a plurality of vibration detection devices, it will be appreciated that other types oF detection device may be used, for example, ~s~
foil switches Eor detecting the brea~ing of a window or the like or infrared or ultrasonic intruder detectors.
Similarly, the dstection devices may be smoke or fire detection devices. Indeed, a combination of these devices in series could be used in the one circuit.
Furthermore, the protective circuit may utilise devices other than switches, such as valves~ transistors, or the like and the invention is not restricted to security equipment. Additionally, impedance elements other than resistors R2 to R7 or diodes D2 to D7 could be employed, for example, zener diodesl transistors or other semi-conductor devices, or indeed other suitable impedance devices~
Instead of using a microprocessor, and related components to monitor the electrical circuit, other suitable means may be used such as described herein.
Additionally, it is envisaged that a memory may be incor-porated in the circuit B in which case the memory may be used to record and store the times at ~hich the devices or switch -21~
were activated or became faulty. Indeed, where devices are mounted on doors or windows~ the openin~ and closing of each door may be individually and separate1y monitored.
Furthermore, it is envisaged that the circuit B could be connected to a telephone line to permit the circuit to be remotely monitored.
Generally th,ere are tWQ major advantages with the present in~entiont Firstly, with; all embodiments described above identical impedan.c.e elements may be used. This ~eads to considerabl,e sa~ings in:manu-facture7 installation and mai'ntenance i~,t:hat a wide range bf components have not to .be manufactured and .stocked. Further the technician working .
on the equlpmen,t s-hould not make an error by fitting t'he wrong compon.e~t~ "Secondly~, where monitori.ng is not res~ricted to one set o~.input :terminals the fact that a bi-state device has ch,anged st.ate or h~s become fauIty will not,limit the monitoring of the circuit~ The remaining bi-state devices c-an continue to.be moni:tored.
In addition to the input terminals 1, 1', terminals 35, 36 are provided in loops 37, 38 conta;ning the vibration detectisn devices 2 to 6 and the anti-tamper devices 30 to 34 respectively. The additional terminals allow the resistance of the circuit to be measured from either end of the loops in the event of a change of state of one of the vibration detection devices 2 to 6 on one of the anti-tamper devices 30 to 34.
A microprocessor 39 is connected to the terminals 1~ 1';
and 35, 36, via a bilateral switch unit 40 and connections 41. The terminals 1, 1'; 35~ 36; are also connected via the bilateral switch unit 40, to four respective alanogue/
digital converters 42, the outputs of which are connected to respective terminals of the microprocessor 39. The analogue/digital converters 42 allow signals From the respective terminals 1, 1'; 35, 36; to be converted to digital signals for the microprocessor 39. A display panel (not shown) is connected to an output of the microprocessor 39, to provide a visual indication whether or not one of the vibration detection devices 2 to 6 or one of the anti-tamper devices 30 to 34 has changed state or is faulty such that the particular device which has changed state or is faulty, can be identified.
In operation, when it is required to lock-up a bu;lding for the night, the protective circuit is preset by placing each vibration detection device into a one state and the microprocessor 39, is set to a mode to deliver an e.m.F.
across the input terminals 1 9 11. If any one of the vibrat;on detection devices 2 to 6, or anti-tamper devices 30 to 34, is faulty, there will be a break in the continuity of the circuit and the microprocessor 39, will only measure the resistance of the circuit from Rl up to the resistance immediately before the faulty component, and thus the faulty component is immediately ;dentified.
If, for example, the faulty component is vibration cletection 4 then the microprocessor 39 by monitoring across the terminals 1, 1', will be able to monitor the vibration detect;on devices 2 and 3 and the anti-tamper devices 30 7 31. In order for the remaining devices 5, 6 and 33, 34, to be monitored, the microprocessor 39 is placed in a mode to monitor across the terminals 35, 1' as well as across the terminals 1, 1'.
By monitoring across the terminals 35, 1', it will be appreciated that the microprocessor will detect the resistors R6 and R5. Thus, should a fault occur in the devices 5 or 6 or 33, 34, this will be readily detected by the micro-processor.
The microprocessor can be placed in a further mode to monitor across terminals 1 and 36 such that should anti-tamper device 32 become faulty, the fault will be readilydetected and id~ntified.
The microprocessor may be placed in yet another mode to monitor across terminals 35~ 36 in addition to any of the modes already described. An advantage of monitoring across all the terminals is that a short circuit in any of the lines can also be readily identified and the position readily located.
Referring now to Figure 3 there is illustrated an electrical protective circuit according to a still further embodiment of the invention, this circuit is substantially similar to that described with reference to Figure 1 with the exception that the devices 2 to 7 in this embodiment of the invention are intruder detecting switches, provided by magnetic reed switches, which may be mounted on, for example, doors, windows or the like so that on opening of a door or window the circuit through the reed switch is opened. In this case the integrator circuits 19 are redundant. However, if it were desired to replace any of the devices 2 to 7 with vibration detection device this could readily be done and the integrator would then come into use.
The operation of this circuit is substantially similar to that described with reference to Figure 1. For examplP, when the reed switch 5 opens, the port;on of the circuit beyond the device 5 is isolated. Accordingly, the resistance of the protective circuit A mon;tored by the control circuit B is:-Rl ~ R2 + R3 + R4 Rl.R2.R3.R4.
Thus, the device on open circuit S will be immediatelyidentified and this information will be displayed on the digital display device 20. Additionally, the relay 21 will trigger an alarm.
Figure 4 illustrates an electrical protective circuit whic.h is again substantially similar to that of Figure 1.
In this case, the devicès 2 to 7 are vibra~ion detection devices and the resistors Rl to R7 are replaced by diodes Dl to D7. The diodes Dl to D7 perform a similar function to that of the resistors of Figure.
Although the invention has been described with particular reference to a protective circuit having a plurality of vibration detection devices, it will be appreciated that other types oF detection device may be used, for example, ~s~
foil switches Eor detecting the brea~ing of a window or the like or infrared or ultrasonic intruder detectors.
Similarly, the dstection devices may be smoke or fire detection devices. Indeed, a combination of these devices in series could be used in the one circuit.
Furthermore, the protective circuit may utilise devices other than switches, such as valves~ transistors, or the like and the invention is not restricted to security equipment. Additionally, impedance elements other than resistors R2 to R7 or diodes D2 to D7 could be employed, for example, zener diodesl transistors or other semi-conductor devices, or indeed other suitable impedance devices~
Instead of using a microprocessor, and related components to monitor the electrical circuit, other suitable means may be used such as described herein.
Additionally, it is envisaged that a memory may be incor-porated in the circuit B in which case the memory may be used to record and store the times at ~hich the devices or switch -21~
were activated or became faulty. Indeed, where devices are mounted on doors or windows~ the openin~ and closing of each door may be individually and separate1y monitored.
Furthermore, it is envisaged that the circuit B could be connected to a telephone line to permit the circuit to be remotely monitored.
Generally th,ere are tWQ major advantages with the present in~entiont Firstly, with; all embodiments described above identical impedan.c.e elements may be used. This ~eads to considerabl,e sa~ings in:manu-facture7 installation and mai'ntenance i~,t:hat a wide range bf components have not to .be manufactured and .stocked. Further the technician working .
on the equlpmen,t s-hould not make an error by fitting t'he wrong compon.e~t~ "Secondly~, where monitori.ng is not res~ricted to one set o~.input :terminals the fact that a bi-state device has ch,anged st.ate or h~s become fauIty will not,limit the monitoring of the circuit~ The remaining bi-state devices c-an continue to.be moni:tored.
Claims (14)
1. An electrical circuit arrangement including:
a plurality of bi-state devices connected therein, each occupying a particular position in the circuit, an impedance element associated with each bistate device such that a predetermined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from said one state to a second state, and means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bi-state device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit.
a plurality of bi-state devices connected therein, each occupying a particular position in the circuit, an impedance element associated with each bistate device such that a predetermined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bi-state devices are caused to change from said one state to a second state, and means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bi-state device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit.
2. An electrical circuit arrangement including:
a plurality of bi-state devices connected therein, each occupying a particular position in the circuit, an impedance element associated with each bistate device such that a predetermined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bistate devices are caused to change from said one state to a second state, means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bistate device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit, said bistate devices being included in a multi-terminal network, and monitoring means operable in accordance with a plurality of modes for monitoring said bistate devices across different combinations of pairs of terminals of said network, to allow not only the particular device which has changed state to.be identified and the position thereof to be located, but to allow devices which have failed or are faulty to be identified and the circuit, to be utilised irrespective of the failure of, or fault in any such device.
a plurality of bi-state devices connected therein, each occupying a particular position in the circuit, an impedance element associated with each bistate device such that a predetermined value of impedance prevails in the circuit when all said bi-state devices are in one state and a value of impedance different from said predetermined value prevails when any of said bistate devices are caused to change from said one state to a second state, means for comparing a parameter of the circuit with a reference parameter to provide an indication of the identity of any bistate device which has changed from said one state to said second state and to identify the position of said changed-state device in the circuit, said bistate devices being included in a multi-terminal network, and monitoring means operable in accordance with a plurality of modes for monitoring said bistate devices across different combinations of pairs of terminals of said network, to allow not only the particular device which has changed state to.be identified and the position thereof to be located, but to allow devices which have failed or are faulty to be identified and the circuit, to be utilised irrespective of the failure of, or fault in any such device.
3. An electrical circuit as recited in claim 1 wherein each said impedance element is a resistor.
4. An electrical circuit as recited in claim 2 wherein each said impedance element is a resistor.
5. An electrical circuit as recited in claim 1 or claim 2 wherein each said impedance element is a diode, zener diode, transistor or other such semiconductor.
6. An electrical circuit arrangement as recited in claim 1 including means for applying an e.m.f. across the circuit, means for measuring the current flowing through the circuit and means for comparing the current flowing through the circuit with a reference current derived from a reference source.
7. An electrical circuit arrangement as recited in claim 1 wherein said bistate devices are security detection devices having a quiescent state and a second state to which the devices are actuated in response to the occur-rence of an abnormal security situation.
8. An electrical circuit arrangement as recited in claim 3 wherein said means for comparing a parameter of the circuit with a reference parameter comprises a comparator device responsive to current flowing through said circuit and having a value in accordance with the resistance of the circuit, and responsive also to a reference current derived from a chain of resistors corresponding to the resistors associated with said bistate devices, said reference current being supplied to the comparator device via a scanning circuit and bistable state device having an output connected to one input of the comparator device, the arrangement being such that when identity exists be-tween the measured current and the reference current, an output signal is produced by said comparator device to identify any bistate device which has changed state.
9. An electrical circuit arrangement as recited in claim 4 wherein said means for comparing a parameter of the circuit with a reference parameter comprises a comparator device responsive to current flowing through said circuit and having a value in accordance with the resistance of the circuit, and responsive also to a reference current derived from a chain of resistors corresponding to the resistors associated with said bistate devices, said reference current being supplied to the comparator device via a scanning circuit and bistable state device having an output connected to one input of the comparator device, the arrangement being such that when identity exists between the measured current and the reference current, an output signal is produced by said comparator device to identify any bistate device which has changed state.
10. A circuit arrangement as recited in claim 8 or claim 9 wherein an output signal from the circuit is supplied via the scanning circuit to frequency measuring apparatus arranged to supply the signal to an audio and/or visual warning indicator via a further scanning circuit such that should the frequency of the signal be within certain predetermined limits, an indication of the particular bistate device which has changed state is provided by said visual indicator.
11. A circuit arrangement as recited in claim 4 wherein said bistate devices include a first series of devices connected by a first conductor to a first terminal and a second series of devices connected by a second conductor to a second terminal, the respective resistors of the bistate devices being connected between said first and second conductors, each conductor having an additional terminal connected together with said first and second terminals to respective first contacts of a switching unit, second contacts of said switching unit being con-nected to said monitoring means operable in accordance with said plurality of modes to monitor the first and second series of devices across different combinations of pairs of said first, second and additional terminals to identify any device which has changed state and any device which has failed or is faulty.
12. A circuit arrangement as recited in claim 11 wherein the monitoring means comprises a microprocessor connected to said first, second and additional terminals via the first and second contacts of said switching unit.
13. A circuit arrangement as recited in claim 11 wherein the contacts of the switching unit are connected to the monitoring means via respective analogue-to-digital con-verters such that signals on said first and second con-ductors present on any pair of said first, second and additional terminals are converted to digital signals for presentation to the said monitoring means.
14. A circuit arrangement as recited in claim 2, wherein a visual display device is connected to an output of the monitoring means to provide a visual indication of any faulty device and the position in the circuit of any device which has changed state.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IE22581A IE810225L (en) | 1981-02-06 | 1981-02-06 | Identifying position in electrical circuit of change of¹state-intruder alarms |
| IE225/81 | 1981-08-06 | ||
| IE20/82 | 1982-01-07 | ||
| IE2082 | 1982-01-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194573A true CA1194573A (en) | 1985-10-01 |
Family
ID=26318779
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408770A Expired CA1194573A (en) | 1981-02-06 | 1982-08-05 | Method and apparatus for identifying the location of a change in state of a part of an electrical circuit |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0072187A1 (en) |
| CA (1) | CA1194573A (en) |
| DK (1) | DK346982A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7999668B2 (en) | 2008-11-17 | 2011-08-16 | GM Global Technology Operations LLC | Series interlock system with integrated ability to identify breached locations |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1766735A1 (en) * | 1968-07-11 | 1971-08-19 | Werner Karl Heinz Dipl Ing | Switching arrangement for in particular electrical room protection systems |
| US3646552A (en) * | 1970-11-10 | 1972-02-29 | Gen Motors Corp | Tamperproof resistance-sensing supervisory system |
| SE402660B (en) * | 1970-11-12 | 1978-07-10 | Securitas Int Ab | FIREPLACE FACILITY |
| JPS5824836B2 (en) * | 1974-10-14 | 1983-05-24 | ノウミボウサイコウギヨウ カブシキガイシヤ | Kasainadonotsuhousouchi |
| DE2632738A1 (en) * | 1976-07-21 | 1978-01-26 | Securiton Ag | Alarm circuit with central station and sensor contacts - has oscillator output coupled to voltage comparators detecting both break and short circuit conditions |
| DE2716506A1 (en) * | 1977-04-14 | 1978-10-19 | Dieter Eberhard | Location of triggered sensor in alarm system - by measuring peak voltage at end of line of series connected sensor contacts having parallel connected resistors |
| US4118700A (en) * | 1977-05-31 | 1978-10-03 | Rca Corporation | Single wire transmission of multiple switch operations |
| US4359721A (en) * | 1978-10-16 | 1982-11-16 | American District Telegraph Company | Two-wire multi-zone alarm system |
| DE2939494B2 (en) * | 1979-09-28 | 1981-07-02 | Siemens AG, 1000 Berlin und 8000 München | Circuit arrangement for intrusion or fire alarm systems |
| DE2939462C2 (en) * | 1979-09-28 | 1983-01-05 | Siemens AG, 1000 Berlin und 8000 München | Process and device for the identification of individual detectors in intrusion or fire alarm systems |
| GB2082358B (en) * | 1980-08-14 | 1984-09-05 | Dynalarm Ltd | Security systems |
-
1982
- 1982-08-03 EP EP82304097A patent/EP0072187A1/en not_active Withdrawn
- 1982-08-03 DK DK346982A patent/DK346982A/en not_active Application Discontinuation
- 1982-08-05 CA CA000408770A patent/CA1194573A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DK346982A (en) | 1983-02-07 |
| EP0072187A1 (en) | 1983-02-16 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |