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Dimming a multicolor LED source to match the characteristics of incandescent lamps is difficult because manufacturing variations, age, and temperature change the actual color value output. To emulate the appearance of dimming incandescent lamps may require a feedback system with color sensor to actively monitor and control the color.
A LED is a long-lived light source, but certain mechanisms can cause slow loss of efficiency of the device or sudden failure. The wavelength of the light emitted is a function of the band gap of the semiconductor material used; materials such as gallium arsenide , and others , with various trace doping elements , are used to produce different ...
LED display of a TI-30 scientific calculator (c. 1978), which uses plastic lenses to increase the visible digit size X-Ray of a 1970s 8-digit LED calculator display. Until 1968, visible and infrared LEDs were extremely costly, on the order of US$200 per unit, and so had little practical use. [23]
In CC drivers, the voltage changes while the current stays the same. CC drivers are used when the electrical load of the LED circuit is either unknown or fluctuates, for example, a lighting circuit where a variable number of LED lamp fixtures may be installed. As an LED heats up, its voltage drop decreases (band gap decrease [1]). This can ...
Shockley derives an equation for the voltage across a p-n junction in a long article published in 1949. [2] Later he gives a corresponding equation for current as a function of voltage under additional assumptions, which is the equation we call the Shockley ideal diode equation. [3]
A 230-volt LED filament lamp, with an E27 base. The filaments are visible as the eight yellow vertical lines. An assortment of LED lamps commercially available in 2010: floodlight fixtures (left), reading light (center), household lamps (center right and bottom), and low-power accent light (right) applications An 80W Chips on board (COB) LED module from an industrial light luminaire, thermally ...
These characteristics are also known as I–V curves, referring to the standard symbols for current and voltage. In electronic components with more than two terminals, such as vacuum tubes and transistors, the current–voltage relationship at one pair of terminals may depend on the current or voltage on a third terminal. This is usually ...
Following theoretical treatments of M.G. Bernard, G. Duraffourg, and William P. Dumke in the early 1960s, coherent light emission from a gallium arsenide (GaAs) semiconductor diode (a laser diode) was demonstrated in 1962 by two US groups led by Robert N. Hall at the General Electric research center [5] and by Marshall Nathan at the IBM T.J ...