GB2273149A - Light bar warning system for vehicles - Google Patents

Abstract

A light bar system comprises a light bar (10) incorporating at least one Warning lamp (12, 14, 16), and a remote control unit (30) arranged to generate a control signal, the control unit (30) including a transmitter (38) for transmitting the control signal to the light bar (10) in the form of electromagnetic radiation, the light bar (10) including a receiver (40) for receiving the control signal and a controller (26) for controlling the light bar (10) in response to the control signal received by the receiver (40). <IMAGE>

Description

LIGHT BAR SYSTEN This invention relates to a light bar system of the type including a light bar incorporating warning lamps and arranged to be mounted upon a vehicle, usually upon the roof of the vehicle, the light bar system further comprising a control unit for controlling the light bar.

Light bars are commonly mounted upon emergency vehicles in order to warn other road users of the presence of the vehicle. Similar light bars may also be provided on other vehicles, for example, breakdown recovery vehicles.

Such light bars commonly take the form of an array of lamps usually in a straight line extending across the width of the vehicle. The lamps may take the form of flashing lamps, rotating beacons, lamps conveying a particular message, spot-lamps, or any other form.

Often, the light bar includes an audible warning device, usually in the form of one or more sirens, although other types of audible warning, for example bells, could be used. It is also known for the light bar to include the sound generator of a public address system for conveying an audible message.

It will be understood that in order to operate each of the devices making up the light bar, a large number of electrical control leads are required, together with a power lead or leads for the light bar. It is common for the light bar to require twelve or more leads coupling the bar to a control panel mounted within the vehicle.

Clearly, fitting such a light bar to a vehicle is not an easy task, especially when it is desired to hide the leads within the vehicle trim. Moreover it is often necessary to drill a hole in the vehicle body in order to pass the leads through the body to the light bar.

Furthermore, the mounting of the control panel may interfere with the existing facia of the vehicle, and existing controls.

If the fitting is not carried out with care, the leads may become damaged during installation or use. Moreover, the light bar, its connections and the control panel become fixtures of the vehicle and so the vehicle must be taken out of service in order to allow repairs and/or maintenance work to be carried out.

If at a later date it is desired to remove the light bar from the vehicle, a large number of leads must be disconnected and removed from the vehicle, and extensive repair work to the body and trim of the vehicle must be carried out.

It is an object of the invention to provide a light bar in which the above problems are mitigated or obviated.

According to the present invention there is provided a light bar system comprising a light bar incorporating at least one warning lamp, and a remote control unit arranged to generate a control signal, the control unit including a transmitter for transmitting the control signal to the light bar in the form of electromagnetic radiation, the light bar including a receiver for receiving the electromagnetic radiation and a controller for controlling the light bar in response to the electromagnetic radiation received by the receiver.

Preferably, the control unit includes a keypad having one or more control keys actuation of which generates an appropriate control signal. The control signal may alternatively be generated in response to the movement of a joystick controller, the use of a microphone, or as a result of the operation of any combination of these input devices or the above described keypad. The control unit preferably further includes an encoder/transmitter for encoding and transmitting the electromagnetic signal in response to the actuation of one or more of said input devices.

The electromagnetic signal preferably takes the form of a carrier the frequency of which is modulated to carry the signal using frequency shift keying. Alternatively, the signal may take the form of a carrier whose frequency is modulated using phase modulation. In further alternatives, the signal could be transmitted using amplitude modulation or single side band modulation.

However, because of the reduced interference, it is preferred to use frequency modulation.

Clearly, using such a light bar system, the only electrical connection to the light bar is a power connection. Thus, only one lead, or where the vehicle includes a wired earth, two leads, need to be connected to the light bar.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of a light bar; Figure 2 is a schematic diagram of the light bar of Figure 1; and Figure 3 is a schematic diagram of a control unit for use with the light bar of Figure 1.

The light bar 10 shown in Figure 1 comprises a plurality of lamps 12, 14, 16 arranged in a rectilinear array, the light bar 10 including a lamp 16 conveying the message "POLICE", although an alternative message may be used depending upon the intended use of the light bar 10. As well as the lamps 12, 14, 16, the light bar 10 includes a sound generator 18 for producing three different siren sounds. The light bar 10 may also include an amplifier 20 forming part of a public address system, the amplifier 20 using the sound generator 18 as its loudspeaker. The light bar 10 is arranged to mounted upon the roof of a vehicle by means of brackets and clamps 22 provided at each end of the light bar 10, the clamps 22 being arranged to engage with the vehicles roof gutters.

The light bar 10 includes a pair of movable spot lamps 24, one provided at each end thereof. Each of the lamps 24 includes, in its mounting arrangement, a pair of motors 25 for adjusting the orientation of the lamp 24 in order to change the area illuminated thereby, one motor 25 being arranged to rotate the lamp 24 about a generally vertical axis, and the other being arranged to rotate the lamp 24 about a generally horizontal axis.

The light bar 10 includes a controller 26 which controls each of the devices of the light bar 10, for example, switches on or off the lamps 12, 14, 16 and controls the motors 15, 25 of the spot-lamps 24. One or more of the lamps may be in the form of a flashing beacon, the flashing effect of which is produced by an electrically driven, rotating reflector positioned adjacent the light source, or alternatively produced by a flash tube and appropriate circuitry.

The light bar 10 is arranged to be operated using a control unit 30 shown schematically in Figure 3. The control unit 30 which may be hand held if desired comprises a plurality of input devices in the form of a keypad 32 including a plurality of keys, a joystick controller 34 and a microphone 36, each of the input devices being arranged to cause a particular control signal to be sent to an encoder and transmitter module 38 on activation thereof. The keypad 32 includes push button keys for operating the sirens, lamps 12, 14, 16 and motors 15 of the beacons. The joystick controller 34 is used to control the motors 25 for adjusting the direction in which the spot-lamps 24 point.The control unit 30 may include two joysticks 34, one for each spotlamp 24, or alternatively, one of the keys of the keypad 32 may be used to control which of the spot-lamps 24 is to be moved by a single joystick. In an alternative embodiment, the control unit 30 may include a plurality of direction keys for operating the spot-lamp motors 25 rather than a joystick controller 34. The microphone 36 is used to operate the public address system. The microphone 36 includes a standard "press to talk" switch 37 which is pressed when it is desired to use the public address system, and released when no message is to be conveyed. The control unit 30 preferably includes an internal power source in the form of batteries, although, if desired, the control unit could be connected by suitable wiring to the battery of the vehicle to which the light bar system is installed.

The control signals generated in response to the operation of each of these input devices are sent to the encoder and transmitter module 38 where the control signals are encoded in the form of a five bit address which identifies the light bar to be operated followed by a four bit data sequence, the four bit data sequence instructing the light bar 10 as to which device is to be signalled, and what operation that device is to perform, for example, the data sequence may instruct the light bar 10 to energise the motor and lamp of one of its flashing beacons.

The encoded digital signal thus produced is then transmitted as a radio signal by the transmitter 38 in the form of a frequency modulated carrier modulated using frequency shift keying, the transmitter transmitting a signal of one frequency for a digital '0' and a different frequency for a digital '1'. Depending upon the operation chosen by the operator, further signals may be transmitted following the four bit data sequence, for example, where the public address system is operated, an FM speech signal is transmitted after the data sequence as explained below. The frequency of the carrier wave is chosen in accordance with local standards in order to result in the minimum possible level of inconvenience to other radio users.

The light bar 10 includes a radio receiver 40 arranged to receive the signal transmitted by the control unit 30.

The receiver 40 includes a processor 42 arranged to separate the encoded message from the carrier wave and to identify whether the incoming signal is in the form of an address followed by a data sequence or otherwise. The encoded signal is fed to a decoder 44 and the controller 26 which confirms that the five bit address is an allowable address, and if so, operates the appropriate device of the light bar 10 in accordance with the instructions contained in the four bit data sequence.

The data sequence identifies which of the devices is to be operated, and the operation of the various devices is explained below. It will be understood that the address part of the signal is important in preventing the operation of the light bar system interfering with the operation of another light bar system in the area.

The lamps 12, 14, 16, sirens and the motors 15 of the beacons are arranged to operate on a simple toggle system whereby, if the device is switched off, one press of the appropriate key will result in a signal being sent to the controller 26 to operate a control driver 45 resulting in the device being switched on. A further press of the same button results in the same signal being sent to the controller 26 switching the device back off. Clearly, the operation of each of these devices requires the use of only a single four-bit data sequence rather than two sequences, one to switch the device on and another to switch it off.

When a signal is received, the data sequence of which indicates that the "press to talk" switch 37 of the microphone 36 has been pressed, the controller 26 is arranged to expect an FM speech signal to follow the data sequence, the speech signal being directed from the receiver 40 to the amplifier 46 and sound generator of the public address system. The strength of the received signal is monitored, and if it falls below a threshold strength for more than a predetermined time period, for example, 1 second, the controller 26 is arranged to revert back to normal operation and await a signal including a five bit address and four bit data sequence.

In an alternative embodiment, the "press to talk" switch 37 may include a second contact arranged to generate the transmission of a data sequence on the release of the "press to talk" switch 37. The controller 26 is in this case arranged to monitor the received signal for such a data sequence, and to revert back to normal operation on receipt of such a data sequence.

When the controller 26 receives a signal including a data sequence indicating that the position of one of the spotlamps 24 is to be changed, the controller 26 is arranged to expect a pulse width modulated signal (generated in response to the operation of the joystick or direction keys) to follow the data sequence, and to operate proportional drivers 47 in response to the pulse width modulated signal. The drivers 47 operate the motors 25 and result in the direction in which the spot-lamp 24 points being adjusted. The use of pulse width modulated signals to obtain proportional control of an electric motor is well known, for example, in relation to the control of radio controlled toys.

Clearly, where the device is mounted upon an emergency vehicle, it is desirable that operation of the device is secure so that the device cannot be operated by unauthorized persons in the area having suitable transmitters. The address part of the signal provides some security but since such protection is relatively easy to overcome, it is advisable to include a method for changing the address part of the transmitted signal. One possibility is that the address part of the encoded signal is changed each time a signal is transmitted following a suitable algorithm known also to the receiving system. An alternative is to use a system whereby the light bar transmits a signal to the control unit each time an encoded signal is transmitted indicating what address to use with the next transmission.However, such a system is likely to be more expensive as both the light bar and control unit would require both a transmitter and receiver.

If it is desired to fit a vehicle with a light bar system in a short space of time, the light bar may be mounted upon the roof of the vehicle in the usual manner, and the power leads passed through a window of the vehicle, or through a door seal, and connected to a suitable power source within the vehicle, conveniently via the cigarette lighter socket of the vehicle. Where the light bar system is to be more permanently attached to the vehicle, a hole may be provided in the roof of the vehicle through which the power lead or leads of the light bar pass for connection to the vehicle electrical system. It will be recognised that since only one or two leads need to pass through the roof of the vehicle, the hole provided in the roof of the vehicle may be smaller, and the task of hiding the leads behind the trim of the vehicle is simplified.The vehicle need not be out of service for a long period of time in order for the light bar system to be fitted or removed.

The control unit may be mounted in any suitable location within the vehicle, the position being chosen to suit the requirements of the operator, and so as not to interfere with the existing controls of the vehicle. The control unit is preferably easily removable from the vehicle so that the operator of the light bar system is able to remove the control unit when leaving the vehicle, and still be able to control the devices of the light bar.

The range of the transmitter is preferably approximately 100 metres allowing the operator to move away from the vehicle whilst still being able to operate the light bar.

Although the above described light bar system uses frequency modulated electromagnetic radiation in the radio frequency bands using frequency shift keying to transmit the signal between the control unit and the light bar, the signal could alternatively be transmitted using phase modulation. It is also possible to utilise amplitude modulation rather than frequency modulation and the chosen electromagnetic radiation could be in frequency bands other than radio, for example, infra-red.

Clearly, the devices provided on the light bar will vary depending upon the intended use of the vehicle upon which the light bar is to be mounted, for example, it may not be necessary to provide sirens or a public address system, or it may be necessary to provide lamps of particular colours.

Claims (10)

1. A light bar system comprising a light bar incorporating at least one warning lamp, and a remote control unit arranged to generate a control signal, the control unit including a transmitter for transmitting the control signal to the light bar in the form of electromagnetic radiation, the light bar including a receiver for receiving the control signal and a controller for controlling the light bar in response to the control signal received by the receiver.

2. A light bar system as claimed in Claim 1, wherein the control unit includes a keypad having one or more control keys actuation of which generates an appropriate control signal.

3. A light bar system as claimed in Claim 1 or Claim 2, wherein the control unit includes a joystick controller movement of which generates an appropriate control signal.

4. A light bar system as claimed in any one of Claims 1 to 3, wherein the control unit includes a microphone the use of which generates an appropriate control signal.

5. A light bar system as claimed in any one of the preceding claims, wherein the transmitter comprises an encoder/transmitter for encoding and transmitting the control signal.

6. A light bar system as claimed in Claim 5, wherein the electromagnetic radiation takes the form of a carrier the frequency of which is modulated to carry the signal using frequency shift keying.

7. A light bar system as claimed in Claim 5, wherein the electromagnetic radiation takes the form of a carrier whose frequency is modulated using phase modulation.

8. A light bar system as claimed in Claim 5, wherein the electromagnetic radiation is encoded using amplitude modulation.

9. A light bar system as claimed in Claim 5, wherein the electromagnetic radiation is encoded using single side band modulation.

10. A light bar system as claimed in any one of the preceding claims, wherein the control signal includes an address part identifying the light bar to be operated and an instruction part identifying which device(s) of the light bar to operate.