The internet is the most popular media for social networking and the
sharing of
pictures and videos. Media-centric phones are gaining market share over
voice-centric
phones, causing a migration to larger size and higher resolution color
displays. The
backlighting of these displays demand higher power from portable
battery sources.
Beyond the display, the mobile handset is becoming a high quality
digital still camera
requiring special lighting functions for video-recording and
photography in low light
environments and consuming more battery peak power and energy.
Light-emitting-diode (LED) technology is widely used to provide
illumination for
the pixels in small format liquid crystal displays (LCDs) in
battery-powered applications.
White light, emitted by the LEDs, is transmitted through a polarizer to
the LCD where
the light can be blocked or attenuated and sent on to RGB color filters
to create colored
light.
The very same LED technology can be used to illuminate a scene when
taking a
picture with a camera phone in dim light conditions. How much light is
needed? How much current will the flash unit consume?
Answering these questions can guide the designer in the selection of
the appropriate LED
flash unit.
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