 An Light-Emitting Diode (LED) is a display and lighting technology used in almost every electrical and electronic product on the market, from a tiny on/off light to digital readouts, flashlights, traffic lights and perimeter lighting. LEDs are also used as the light source in multimode fibres, optical mice and laser-class printers.
Several Colours
LEDs are semiconductor diodes that typically emit a single wavelength of light when charged with electricity. The colours of the emitted light depends on the composition and condition of the semiconducting material used. An LED can be used as a regular household light source. The colour of an LED is determined by the semiconductor material, not by the colouring of the 'package' (the plastic body). LEDs are available in red, orange, amber, yellow, green, blue and white. LEDs of all colours are available in uncoloured packages which may be diffused (milky) or clear (often described as 'water clear'). The coloured packages are also available as diffused (the standard type) or transparent.
Applications
LEDs and liquid crystal displays (LCDs) are widely used in combination as in this printer control panel. In the early 1970s, red LEDs were used in the first digital watches, but were superseded by lower-power LCDs within a few years. LEDs still use more power than LCDs, but less power than incandescent bulbs. LEDs and LCDs coexist on countless devices where the LEDs provide the status lights, and the LCDs display data. In addition, white LEDs can provide the backlight for LCD screens. LEDs can be applied everywhere in our daily life, from street such as street lamp, traffic light, to our home devices such as remote controls, such as for TVs and VCRs, often use infrared LEDs, elevator push button lighting, or computers.
Benefits
It is energy-saving! LEDs can produce more light per watt than do incandescent bulbs; this is useful in battery powered or energy-saving devices.
It is more efficient! LEDs can emit light of an intended colour without the use of colour filters that traditional lighting methods require. This is more efficient and can lower initial costs.
It is ideal for frequent on-off switch! LEDs are ideal for use in applications that are subject to frequent on-off cycling, unlike fluorescent lamps that burn out more quickly when cycled frequently, or HID lamps that require a long time before restarting.
It is more solid! LEDs are difficult to damage with external shock. Fluorescent and incandescent bulbs are easily broken if dropped on the ground.
It is longer life-cycle! LEDs can have a relatively long useful life. On average, the life-cycle can be 35,000 to 50,000 hours, though time to complete failure may be longer. Fluorescent tubes typically are rated at about 30,000 hours, and incandescent light bulbs at 1,000–2,000 hours.
It lights up quickly! . A typical red indicator LED will achieve full brightness in microseconds; LEDs used in communications devices can have even faster response times.
It is small! LEDs can be very small and are easily populated onto printed circuit boards. top |
