GB2278216A - Loudspeakers - Google Patents

Abstract

A control module (e.g. 351) for at least one loudspeaker (381) for public address (pa), eg, in remote or hazardous areas such as offshore oil/gas platforms to provide audible warnings, provides means by which the at least one loudspeaker can be operated from a first control station(s) (10) via a first cable(s) (15) and/or from a second remote control station(s) (60) via an electromagnetic link(s). <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO LOUDSPEAKERS BACKC-ruND TO r NENTtION- This invention relates to loudspeakers, and in particular to a control module for at least one loudspeaker for public address, for example, In remote or hazardous areas such as offshore oil/gas platforms or onshore industrial sites.

Loudspeakers are often used in hazardous areas to provide audible warnings as an integral part of the safety features of the area. In the event of any serious accidents or emergency procedures it is imperative that the work-force and any emergency teams can be given precise information regarding the incident and what steps must be taken such as decks to be cleared and/or the procedure and route for the installation to be evacuated.

In such circumstances it is imperative that the loudspeakers function for as long as possible in emergency conditions, especially during fire, as lives may be lost if such loudspeaker equipment is affected by a fire.

Conventional hardwire public address systems employ a fixed control station whereby a microphone, amplifier and power supply is connected to speakers via cabling. A disadvantage with such systems is that if any of the cables are severed at least some of the speakers will be lost from the system, or if the amplifiers are destroyed in an explosion or fire, for example, the system will be inoperable.

Although some existing systems have monitoring systems incorporated into there design - which assist with the every-day maintenance of a fully operational system such monitoring systems do not prevent the loss of at least part of the public address system in the event component failure. Another disadvantage is that cabling is expensive, and in some cases where installations are very old, it is often difficult to add to the system or run new cables.

GB 92 02 5.3, filed by the present Applicant, discloses a remote controlled loudspeaker for use in a public address system which operates in a similar way to a conventional public address system excepting that radio waves are used instead of cables to transmit voice and alarm messages. Therein, each speaker acts as a separate system as none of the speakers are attached to each other.

Each loudspeaker can be accessed via any number of authorised users, for example, a helicopter, standby vessel, etc. Any number of loudspeakers can be installed and each speaker has alarm circuits fitted internally, again not relying on a base unit for operation.

Although wireless loudspeakers are particularly suited to hazardous environments - such as the offshore environment - where cabling is difficult to install and maintain, most existing installations already have an existing public address system.

It is, therefore, often impractical to replace an existing system with totally new systems due, for example, to cost implications.

It is further, desirable to provide a back-up to the conventional hard-wire system.

It is an object of the present invention to obviate or mitigate at least some of the aforementioned disadvantages in the prior art.

It is a further object of the present invention to seek to provide the aforementioned desirable features.

SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a control module for at least one loudspeaker wherein the control module provide means by which the at least one loudspeaker can be operated from a first control station(s) via a first cable(s) and/or from a second remote control station(s) via an electromagnetic link(s).

Each loudspeaker preferably comprises a main housing containing an electrical to audio transducer.

An explosion-proof body may be provided within the main housing, the control module being located within the explosion-proof body.

Alternatively, an explosion-proof body may be provided which body is separate from the at least one loudspeaker, the control module being located within the explosion-proof body. In such case the control module is connectable to the at least one loudspeaker.

The control module may normally be powered by a mains power supply, and may have a back-up battery power supply for provision of emergency power in circumstances where the mains power supply is cut-off from the control module.

The control module may include a transeiver by which the control module can be operated from a second remote control station(s) via an electromagnetic link(s) and by which electromagnetic signals can be sent from the at least one loudspeaker to (an) other loudspeaker(s) and/or to a control station(s).

The control module preferably includes sensing means by which the presence or absence of a signal(s) from a first cable(s) may be detected and the operation of the at least one loudspeaker suitably controlled.

The control module may further provide illumination means which illuminate under emergency conditions or in noisy areas.

According to a second aspect of the present invention there is provided a public address system comprising one or more loudspeakers, and a control module for at least one of the one or more loudspeakers, wherein each control module provides means by which the respective at least one loudspeaker can be operated from a first control station(s) via a first cable(s) and/or from a second remote control station(s) via an electromagnetic link(s).

Preferably each of the control modules may include decoding means whereby, in use, selected at least one loudspeakers only may be operated by each of the first control station(s) and/or second remote contro stations if he tarticuiar stat on transmits a suitably encoded signal to the control module of (each of) the selected at least one loudspeakers.

Gn receiving a suitably encoded signal the control module will cause the at least one loudspeakers to operate, for example, by producing an audio message, alarm tone or so-called "confidence bleep" to confirm to bystanders that the at least one loudspeakers is/are operational.

DESCRIPTION OF EMBODIMENTS Two embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which Fig 1 is a schematic block diagram of a public address system including a plurality of control modules according to the present invention; Fig 2 is a schematic block diagram showing a first embodiment of a control module according to the present invention; Fig 3 is a more detailed schematic cross sectional side view of the control module of Fig 2; Fig 4 is a schematic cross-sectional side view of a second embodiment of a control module incorporated within a loudspeaker according to the present invention; Fig 5 is a schematic view of one embodiment of remote control electronics for the control module of Fig 4; and Fig 6 is a schematic view of a further embodiment of remote control electronics for the control module of Fig 4.

FIRST EMBODIMENT Referring fIrstly to Fig 1, there is shown a public address system, generally designated 5, comprising a control centre or station 10 having an output wire 15 extending from an output 20 thereof.

Each of a plurality of branch wires 251, , 25n extend from respective points along the output wire 15 to each of first inputs 301, ' 30n of each of a plurality of control modules 351, ....., 35n. An output 361t , 36n of each of the plurality of control modules 351 --- , 35n are in turn connected to an input 371, ....., 37n of a respective loudspeakers 381, ......, 38n Each loudspeaker 381, , 38n comprises a main housing containing an electrical to audio transducer.

Each of the control modules 351 --- , 35n are powered from a mains power supply 40. Further, the output wire 15 - and, therefore each of the contol modules 351, ......, 35n - is connected to monitoring circuitry 45 which monitors each of the loudspeakers 381, , 38n either in a continuous or intermittent basis to determine whether or not each loudspeaker 381, , 38n is still connected to the control station 10.

As can be seen the plurality of loudspeakers 381, ..., 38n are connected to, and may be, addressed by the control station 10. If, however, any connection between the control station 10 and any of the control modules 351, ....., 35n are broken for whatever reason - eg. explosion or fire - then loudspeakers 381, , 38n down-wire of the breakage are rendered unaddressable by the control centre 10.

Referring to Fig 1, each of the control modules 351, ......, 35n is also connected to an antenna or aerial 501, ..... , 50n which antenna is connected to a second input 551 55n thereof. This provides that each control module 351, ......, 35n, and therefore, loudspeaker 381, ...... , 38n can be remotely addressed by one or more remote control stations 60 located cn, for example, a helicopter, rescue vessel cr the '-ke.

Each control module 351 -, 3~ further 35n further provides a battery back-up 651, , 65n to provide electrical power to the control modules 351 ------, 35- in case the connection between the control modules l ' 35n and the mains power supply 40 is broken.

It can be seen from the foregoing that if the connection between any of the control modules 351, ......., 35n and central station 10 is broken for any reason, the control modules 351,......, 35n can still be addressed by the remote control station 60. Further if the connection between any of the control modules 357, ......, 35n and the power supply 40 is broken for any reason the control modules 351,......, 35n can be supplied with electrical power for a limited time by the batter back-up 651, ......, 65n Each of the loudspeakers 381, , 38n can, therefore, operate as part of a conventional hard-wired public address system, as part of a remotely operated public address system, or alternatively as a stand-alone loudspeaker addressed either by a central control station 10 or by a remote control station 60.

Referring to Fig 2 there is shown a schematic block diagram of a first embodiment of a control module, generally designated 35, according to the present invention. An input of a speaker unit 38 is connected to an output of a solid state relay 70 provided in the control module 35. The relay 70 has two inputs 75, 80, the first 75 of which is connected to the central control station (not shown), in use. A sense input 90 of the relay 70 is connected to a micro-computer 85 which controls the position of the relay 70. The micro-computer 85 is itself operated via data received by a radio transeiver 95 which may receive signals from a remote control station (not shown) via an antenna (not shown), and which is connected to the second input 80 of the relay 70 via an audio amplifier 100 and transformer 105. The transelver may also be used to transmit signals - input rom a icrotnone 96 - from the control module 35 via the antenna to a control station 10, 60 or other control module 35.

The control module 35 further provides a xenon discharge PC3 and lamp 110, which lamp 110 illuminates on receipt of emergency code signals from a control station 10, 60.

The control module 35 also provides a status indicator 15 controlled by the micro-computer 85 which indicates if the control module 35 is being addressed by a central control station 10 or by a remote station 60.

The control module 35 further comprises a power supply board 120 powered by a 240V AC mains supply. The power supply board 120 is connected to the audio amplifier 100, transeiver 95 and micro-computer 85 via a regulator unit 125.

The power supply board 120 is further connected to a battery back-up, generally designated 65, via a charging circuit 130.

It is apparent from the foregoing that the control module 35 may be incorporated into an existing hard-wire public address system, thus eliminating the unnecessary purchase of additional loudspeakers.

Referring to Fig 3 there is shown a more detailed schematic cross-sectional side view of the control module of Fig 2. As can be seen from Fig 3 the status indicator 115, transformer 105 (1OOH line), microcomputer 85, transeiver 95, amplifier 100, and regulator unit 125 are spaced apart and retained in association with one another by an assembly 135 of retaining rods 140. The assembly 135 is housed in an EXd cylindrical housing 145 made, for example, from offshore industry standard 316 stainless steel which makes the control model 35 not only explosion proof, ruggedised enough to withstand the harsh environment of the North Sea, but light enough to be installed by one man.

The housing 145 is of volume 2 litres and provides a glass status window 150 at a first threaded end 151 thereof. The window 150 allows viewing of the status indicator 115. The glass window 150 is mounted between a co-acting retaining plate 155 and threaded lid 160, the lid 160 being threadably connectable to the first end 151.

A threaded second end 165 of the housing 145 is threadably connectable to a threaded bottom plate 170, which bottom plate 170 has a bushing 175 passing therethrough.

The bottom plate 170 is connected to a 316 stainless steel Exe enclosure 180. The Exe enclosure 180 provides a hinged door 181 having a seal 182 therearound and a lock 183 therein. The Exe enclosure 180 further provides an Exe isolator switch 184.

On an outermost surface of the Exe enclosure 180 there are provided a gas vent 185 and cable glands 186.

Within the Exe enclosure 180 there is provided an Exe battery enclosure 186 wherein there is provided the backup battery 65. Also provided within the Exe enclosure 180 there is a "clippon" terminal rail 187 having "clippon" terminals 188, fuses 189 and earth terminals 190.

Additional features of the control module 35 which should be appreciated are as follows: The control module 35 is transparent to conventional 100 Volt line monitoring systems. However, in addition the control module 35 allows monitoring of the condition not only of the 100 volt line, but transmits this information together with self diagnostic information to a central receiving station 10. This feature makes the control module 35 not only easily maintained but cost effective to maintain.

The control module 35 may take its power from a conventional 240 volt power supply. However, the integral back-up battery power supply 65 comprising batteries and charger with a capacity, for example, of 10 amp/hour will provide emergency operational power for up to five hours.

Additional unique features of the control module 35 include an integral visual xenon -slashing beacon which activates on receipt of emergency messages or, if desired, will operate on receipt of routine messages from the conventional public address system - an invaluable feature when loudspeakers 38 are situated in noisy areas.

Another feature is the facility for talkback. Each control module 35 can act as an out-station. During routine operation users will have the ability to relay messages to control stations 10, 60. In the event of an emergency the facility to disable any number of modules is available (leaving only modules at muster stations active for example).

Built into each embodiment there may be an individual alarm generator board which enables the broadcast of up to 9 different programmable alarms. These alarms can be initiated via a controller which can be situated anywhere within the vicinity of the system.

SECOND EMBODIMENT Referring now to Fig 4 there is shown a second embodiment of a control module according to the invention contained within a loudspeaker 235. Such a combined control module and loudspeaker 235 may be used in replacement of a conventional loudspeaker in a hard-wire public address system to provide at least some of the advantages of the present invention.

The loudspeaker 235 comprises a main housing 202 having a cylindrical portion 203 and a frustoconical horn portion 204. The housing 202 is formed of an anti-static compound (for example, CENELEC EN 50014-6). One end 205 of the housing 202, remote from the frustoconical portion 204, is provided with a cover portion 206 which is sealed in position by a silicone rubber O-ring 207.

A flame-proof, explosion-proof body 208 made from aluminium alloy (DS-4261 equal to LM6) is located within the cylindrical portion 203 of the housing 202. The body 20 extends zhrouqh an aperture 209 in the main housing 2t2 within trie horn 204 of the housing 202 and is sealed b a cork sealing gasket 210 and a silicone rubber O-ring 2:, an wintered disc 217. At the other end of the housing 202 the body 208 is closed by an explosion-proof enclosure cap 212 and is sealed by a further silicone 0ring 213 within the cylindrical portion 203 of the housing 202.

An antenna (not shown) is provided within the cover portion 206 of the housing 202. A bracket 214 is fixed to the main housing 202 by a suitable fixing means such as a screw 215. The loudspeakers 35 may, therefore, be mounted in any desired location.

Control electronics 216 for the loudspeaker are located within the explosion-proof body 208 and are described in more detail below.

As shown in Fig 5, when addressed by a remote control station (not shown), an RF carrier - set to the correct frequency - is received by an RF transeiver unit 217. The modulation from the transeiver 217 is then passed to a processor unit 218 where it is fed to a CTCSS decoder.

This is programmed for detection of one of, for example, 238 standard sub-audible tones. If a tone is detected, the audio signal is then filtered to remove any high frequency noise and passed to a mute circuit 219. The mute circuit 219 ensures that in a condition of no received carrier into the transeiver 217, no unwanted noise is fed to a last amplifier. From a volume control the audio signal is fed to a power amplifier which then feeds the signal to the speaker.

In a third embodiment of the invention there is provided an enhanced version of the remote control electronics as shown in Fig 6, wherein after a signal is passed through a mute circuit 319 it is fed to an electronic volume control and a DTMF transeiver 320 (or decoder).

To enable the audio paths in this third embodiment, the correct DTMF sequence must be received, which upon being decocet is fed to an 8 bit Micro C~n.roller (MCU? 32- were -t is checked for validity and also checked to establish identity, as each unit has its own individual identity nu.^^r If all the above parameters are met then the MCU 321 carries out such commands as change channel on radio, adjust volume level, turn CTCSS decoder on/off, unmute speaker, and generate emergency alarms.

When the audio path has been opened by the MCU 321 then the speech is fed to the power amplifier which then feeds the speaker.

SUMMARY The embodiments of the inventions hereinbefore described are given by way of example only and are not meant to limit the scope of the invention in any way.

Particularly, it can be appreciated that in the event of an emergency such as a fire or explosion a control module according to the invention may be operated from a remote location such as a helicopter in the vicinity.

Vital instructions may be given to personnel on the installation via at least one loudspeaker connected to the control module, thus aiding evacuation from the area. In normal circumstances, however, the control module may allow the at least one loudspeaker to act as part of a hard-wire public address system or a remote public address system.

Claims (12)

Claims

1. A control module for at least one loudspeaker wherein the control module provides means by which the at least one loudspeaker can be operated from a first control station(s) via a first cable(s) and/or from a second remote control station(s) via an electromagnetic link(s).

2. A control module as claimed in claim 1, wherein each loudspeaker comprises a main housing containing an electrical to audio transducer.

3. A control module as claimed in claim 2, wherein an explosion-proof body is provided within the main housing, the control module being located within the explosionproof body.

4. A control module as claimed in claim 1 or 2, wherein an explosion-proof body is provided which body is separate from the at least one loudspeaker, the control module being located within the explosion-proof body, the control module being connectable to the at least one loudspeaker.

5. A control module as claimed in any of claims 1 to 4, wherein the control module may normally be powered by a mains power supply, and has a back-up battery power supply for provision of emergency power in circumstances where the mains power supply is cut-off from the control module.

6. A control module as claimed in any of claims 1 to 5, wherein the control module includes a transceiver by which the control module can be operated from a second remote control station(s) via an electromagnetic link(s) and by which electromagnetic signals can be sent from the at least one loudspeaker to (an) other loudspeaker(s) and/or to a control station(s).

7. A control module as claimed in any of claims 1 to 6, wherein the control module includes sensing means by which the presence or absence of a signal(s) from a first cable(s) may be detected and the operation of the at least one loudspeaker suitably controlled.

8. A control module as claimed in any of claims 1 to 7, wherein the control module may further provide illumination means which illuminate under emergency conditions or in noisy areas.

9. A public address system comprising one or more loudspeakers, and one or more control modules for at least one of the one or more loudspeakers, wherein each control module provides means by which the respective at least one loudspeaker can be operated from a first control station(s) via a first cable(s) and/or from a second remote control station(s) via an electromagnetic link(s).

10. A public address system as claimed in claim 9, wherein each of the control modules includes decoding means whereby, in use, selected at least one loudspeakers only may be operated by each of the first control station(s) and/or second remote control station(s) if the particular station transmits a suitably encoded signal to the control module of (each of) the selected at least one loudspeakers.

11. A control module as hereinbefore described with reference to Figs 2-3 or Figs 4 to 6.

12. A public address system as hereinbefore described with reference to Fig 1.