Replacement of traditional light sources, such as incandescent light bulbs, by solid state light sources, such as light emitting diodes (LEDs), is often associated with a number of issues. For example, the light output provided by a LED typically has a different spectral composition than the light output of a traditional light source, for example based on an incandescent filament. Further, the spatial intensity distribution of the light output of a LED is typically different than the spatial intensity distribution of the light output provided by a traditional light source. Moreover, heat generated during operation of the LEDs may damage or deteriorate performance of the LEDs. Therefore, design of LED-based lighting devices typically involves considerations relating to heat management.
WO 2010/080565A1 discloses a retrofit LED light bulb with additional features such as a backup battery, a camera, a detector/sensor, an audio device, a communication device, a camera, and/or a repeater. As LEDs are substantially smaller than incandescent and fluorescent light bulbs, there is space available in the LED light bulb for housing such extra features. The additional features are arranged within a shell behind the LEDs together with circuitry for converting line voltage into voltage suitable for the LEDs.
The positioning of the extra features within the shell behind the LEDs may prevent optimal performance or operation of at least some of the extra features since input to the extra features from the surrounding environment, and/or output from the extra features to the surrounding environment, may be obstructed by the shell and the LEDs. It would be advantageous to provide alternative lighting devices which allow improved performance for at least one such additional feature without adversely affecting the optical performance of the lighting device.