LEDs in Mobile Appliances
Many handsets now feature illuminated keypads that require the use of up to 12 blue or white LEDs. Also, LEDs are used as backlights for the liquid-crystal display screens in handsets. While many models use monochrome green or blue devices, an increasing number of handsets now feature full-color screens that are backlit using white LEDs.
|Samsung pocket PC|
The number of handsets shipped with color screens grew by around 140% from 2002 to 2003 and exceeded 200 million units. The development of higher-performance devices, which reduces the number of LEDs per screen, has been offset by some phones having two screens.
According to Strategies Unlimited, the total market for HB-LEDs in mobile appliances in 2003 was $1.37 billion. LCD backlights and keypad backlights accounted for 42% and 45%, respectively, of this figure.
Another emerging function is the use of white LEDs in the camera flashes of mobile phones equipped with digital cameras. By 2005, more than 90% of phones in Japan and Korea will be equipped with a camera.
Also, RGB multichip packages are being used for ringer functions and other features, while Nokia has introduced a phone with a strip of LEDs capable of writing a message in the air.
Mobile appliances other than handsets, notably personal digital assistants (PDAs) and digital cameras, also use LEDs as backlights in their LCD screens. While screens on these types of portable device are expected to proliferate, the penetration of LCDs in handsets can be expected to saturate in the next few years. Also, these small LCD screens will face competition from OLED displays.
The unit demand for keypad applications is growing thanks to the widespread use of blue LEDs in the Asian market, the appearance of blue keypads in Europe and the US, and the adoption of white keypad backlights by major manufacturers such as Nokia and Motorola. However, there is severe price competition and erosion due to the ramp in capacity among blue LED manufacturers in Asia.