Networked communication devices

• US 7,369,062 B2
• Filed: 07/10/2003
• Issued: 05/06/2008
• Est. Priority Date: 07/10/2002
• Status: Expired due to Fees

• Current Assignee: Saf-T-Glo Limited
• Original Assignee: Saf-T-Glo Limited
• Inventors: Stokes, Peter David, Braithwaite, Stephen John, Leach, Daniel
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US10/520,892
• Publication Number:
  US 20060111793A1
• Time in Patent Office: 1,762 Days
• Field of Search: 340/945, 340/321, 340/332, 340/952, 340/953, 340/539.1, 455/420, 702/182
• US Class Current: 340/945
• CPC Class Codes: G05B 15/02 electric

Abstract

An aircraft emergency lighting system includes a plurality of light units arranged to guide passengers to and to identify exits in an emergency. The light units communicate wirelessly with a remote master control unit operable from the cockpit using a low power spread spectrum signal centered on a single frequency to avoid interference with onboard aircraft control and communication systems. The light units are arranged to receive and transmit any signal to and from the master controller whereby only some of the light units need be within range of the master controller. The light units include battery operated LEDs and cycle between an inoperable (sleep) condition and an operable (awake) condition to conserve power consumption and extend battery life.

Claims

1. A system for a vehicle, said system comprising a plurality of networked communication devices arranged to communicate wirelessly with a master controller using spread spectrum communication to control operation of said devices and/or to provide information relating to the status of said devices, and wherein said devices are arranged to receive/transmit any signal so that signals to and from said master controller are cascaded between said devices in a random manner and wherein each device has its own battery power source and is arranged to cycle between an operable (awake) condition in which it can receive/transmit a signal and an inoperable (sleep) condition in which it does not receive/transmit a signal and said devices cycle between the operable and inoperable conditions in a random manner.

2. The system according to claim 1 wherein the cycle time is of the order of a few seconds.

3. The system according to claim 1 wherein each device can be switched between two cycle modes with different intervals between the operable and inoperable conditions.

4. The system according to claim 3 wherein stand-by and armed modes of operation are provided with said stand-by mode having a longer cycle time than said armed mode.

5. The system according to claim 1 wherein each device has a listening time in the awake condition of a few milliseconds.

6. The system according to claim 1 wherein each device is provided with a unique identification code and said master controller can transmit a polling signal that requires each device to transmit its unique identification code.

7. The system according to claim 6 wherein said identification codes are generated by an initialization signal during initial set-up of the system.

8. The system according to claim 1 wherein each device is operable in response to a test signal from said master controller to transmit a signal to indicate if the device is operational.

9. The system according to claim 1 wherein said master controller is operable to emit a signal centered on a single frequency.

10. The system according to claim 1 wherein said battery is replaceable, for example a lithium battery.

11. The system according to claim 1 wherein said battery is rechargeable.

12. The system according to claim 11 wherein each device includes a charging circuit to control operation of a photovoltaic cell to charge said battery if the charged level of the battery drops below a pre-determined limit.

13. The system according to claim 1 wherein each device provides a visual and/or audible warning of failure of said battery.

14. The system according to claim 1 wherein said networked devices comprise light units of an emergency lighting system.

15. The system according to claim 1 wherein at least two master controllers are provided for communicating with said networked devices using spread spectrum communication.

16. The system according to claim 15 wherein one of said master controllers is a primary controller and each additional master controller is a secondary controller operable automatically in response to activation of the primary controller.

17. In a passenger vehicle, a wireless emergency lighting system for guiding passengers to an exit, the system comprising a master controller and a plurality of battery operated light units arranged, when illuminated, to identify a route to said exit, each light unit being capable of receiving and transmitting a spread spectrum signal and being arranged to receive and retransmit any signal so that signals to and from said master controller are cascaded between said light units in a random manner, wherein each light unit is arranged to cycle between an operable (awake) condition in which it can receive and transmit a signal and an inoperable (sleep) condition in which it does not receive and transmit a signal, wherein said light units are arranged to cycle between said operable and inoperable conditions in a random manner.

18. The vehicle of claim 17 wherein said light units comprise at least one exit identifier placed at said exit to identify where said exit is.

19. The system according to claim 17 wherein said light units comprise escape path markers positioned at or near floor level along one or both sides of an aisle along which passengers can move to said exit.

20. A method of operating an emergency lighting system comprising providing a plurality of light units each capable of receiving and transmitting a spread spectrum signal, arranging said light units to receive/transmit any signal so that signals to and from a master controller are cascaded between said light units in a random manner, providing each light unit with its own battery power source, arranging each light unit to cycle between an operable (awake) condition in which it can receive/transmit a signal and an inoperable (sleep) condition in which it does not receive/transmit a signal, and arranging said light units to cycle between said operable and inoperable conditions in a random manner.