Activating a light source in dependence on previous power cycle duration

1. A light device comprising at least one light source, a memory and at least one controller configured to, upon being powered on:

read a value from said memory, said value based on how long said light device was continuously powered on before said light device was last powered off,

determine from said value whether said light device was continuously powered on for more than a predetermined period before said light device was last powered off, and

activate said at least one light source upon determining that said light device was continuously powered on for less than said predetermined period before said light device was last powered off.

2. A light device as claimed in claim 1 , wherein said at least one controller is configured to transmit an information signal upon activating said at least one light source, said information signal indicating that said light device was continuously powered on for less than said predetermined period before said light device was last powered off.

3. A light device as claimed in claim 1 , wherein said at least one controller is configured to control said at least one light source to assume a state active just before said light device was last powered off upon determining that said light device was powered on for more than said predetermined perioded before said light device was last powered off.

4. A light device as claimed in claim 3 , wherein said at least one controller is configured to assume said state if said light device has been configured with a preference to turn on in a last known state.

5. A light device as claimed in claim 4 , wherein said at least one controller is configured to read a configuration value of a Zigbee StartUpOnOff attribute and determine that said light device has been configured with a preference to turn on in a last known state if said configuration value equals 0xff.

6. A light device as claimed in claim 4 , wherein said at least one controller is configured to receive a configuration input indicating that said light device is to be configured with a preference to turn on in a last known state and configure said light device to turn on in a last known state in dependence on said configuration input.

7. A light device as claimed in claim 1 , wherein said value depends on whether said light device was continuously powered on for more than a predetermined period before said light device was last powered off.

8. A light device as claimed in claim 7 , wherein said at least one controller is configured to set said value to a first value upon determining that a timer has elapsed and control said at least one light source to assume a state active just before said light device was last powered off if said value read from said memory equals said first value.

9. A light device as claimed in claim 1 , wherein said at least one controller is configured to receive a configuration input indicating a time period and configure said predetermined period to equal said indicated time period.

10. A method of activating at least one light source of a light device, comprising, upon said light device being powered on:

reading a value from a memory of a light device, said value based on how long said light device was continuously powered on before said light device was last powered off;

determining from said value whether said light device was continuously powered on for more than a predetermined period before said light device was last powered off; and

activating said at least one light source upon determining that said light device was continuously powered on for less than said predetermined period before said light device was last powered off.

11. A method as claimed in claim 10 , further comprising controlling said at least one light source to assume a state active just before said light device was last powered off upon determining that said light device was continuously powered on for more than said predetermined perioded before said light device was last powered off.

12. A method as claimed in claim 11 , wherein said state is assumed if said light device has been configured with a preference to turn on in a last known state.

13. A computer program or suite of computer programs comprising at least one software code portion or a computer program product storing at least one software code portion, the software code portion, when run on a computer system, being configured for carrying out the method of claim 10 .