REDUCING POWER CONSUMPTION IN A PORTABLE ELECTRONIC DEVICE WITH A LUMINESCENT ELEMENT

A portable device including at least one luminescent element, a camera including an image sensor for activation to produce an electrical image signal representative of an image sensed by the image sensor, and a camera signal processor including a camera memory for storing the image signal for subsequent reproduction of the image, the device also including a luminescence controller for controlling a brightness of the luminescent element, the camera signal processor is also arranged to activate the image sensor intermittently to produce sample signals representative of ambient light during periods in which the image signal is not being stored in the camera memory, the luminescence controller being responsive to the sample signals to modulate progressively the brightness of the luminescent element as a function of a brightness of ambient light. In a portable device including at least one luminescent element, a plurality of human-interface actuators, at least one sensor responsive to an ambient variable relating to usage of the device, a timer and an activation controller for controlling activation and deactivation of the luminescent element, the activation controller is responsive to different conjunctions of signals from the actuators, the sensor and the timer to activate selectively and to extinguish the luminescent element, whereby to economise power consumption of the luminescent element when the conjunction of signals is indicative of user inactivity of the device.