Leds
here has been no fundamental advances in traditional ligh
LED was discovered accidentally in the last century (1907). In developing the first stage, carborundum crystals were used as light emitting active material. Nick Holonyak Jr. of General Electric Company has developed a practice of the visible spectrum, first LED in 1962.
Within LED: An LED is a semiconductor device that converts electrical energy directly into light. The most important part of an LED is the semiconductor chip located in the center of the bulb. In its most basic level, the semiconductor consists of two regions. The p-region contains positive electric charges, while the N – contains negative electrical charges.
Construction: One way to build an LED is to deposit three layers of semiconductor on a substrate. Among P-type and n-type semiconductor layers, an active region emits light when an electron and hole recombine. Given the combination of a pn diode,
when the diode is biased, the holes in the p-type material
n-type material electrons are driven in the active region, and light Solidstate produced by a process called electroluminescence. In this particular design, the layers
that the LED emits light all the way around the shell structure and the
LED structure is placed in a small cup for reflection light of the active layer is reflected in the direction desired output.
LED emission and determining the color: When sufficient voltage is applied to the chip through the wires of the LED, the current begins to flow. The electrons in the 'n' region have sufficient energy to move across the junction in the region of the 'p'. When an electron moves sufficiently close to a positive charge on the 'p' region, re-combine two counts. For each recombination of a quantum negative and positive charge of electromagnetic energy is emitted as a photon. LED emits incoherent narrow spectrum LED emits incoherent light when electric biased in the direction of progress. This effect is a form of electroluminescence. The color of light emitted depends on the chemical composition of semiconductor materials used and may be near ultraviolet, visible or infrared. Usually a combination of chemical elements such as gallium, arsenic and phosphorus is used.
LED Terminology:
AlInGaP: The preferred technology of LED chips that contain aluminum, indium, gallium and phosphorus to produce red, orange and amber
colors
Bin: The systematic breakdown of the distribution of performance parameters (flow, color or AAC, and V) in small groups that meet aesthetic
assembly requirements
Binning: District of manufactured parts distribution common operating tray (color, flow and voltage)
Candela (Cd): The luminous intensity as defined by the metric standard international (SI). The term, maintains since the early days of enlightenment, we define a standard candle of a fixed size and composition as a basis for assessing the intensity of other sources light
Chromaticity diagram: A horseshoe shaped line connecting the chromaticity color spectrum
Tone: The situation in which the appearance of different colors is similar, for example, matching blue and pink
Brightness: a range of gray tones between white and black
Chroma: the degree of departure from gray of the same lightness and increased color, for example, red, red and pure red
Color Range: The range of colors in the chromaticity diagram includes the time of combining different sources
Color spectrum: All the wavelengths perceived by the human eye, usually measured in nanometers (nm)
Color temperature: The effect heating an object until it shines brightly. The radiation emitted, and the apparent color, changes proportional to temperature. This can be easily envisaged when is considered the hot metal in a forge that glows red, orange, and then
white as the temperature increases.
Cool white: The light with a correlated color temperature between 5000 º K and 7500 º K, is perceived as something blue
Correlated color temperature: The phrase used to describe the temperature at a Planckian black body radiator and a light source seem to agree, usually specified in degrees Kelvin (K)
Color rendering index (CRI): The calculated rendered color of an object. The higher the CRI (based on a scale of 0-100), the most
colors appear natural. The natural outdoor light has a CRI of 100. Common light sources have a wide range of CRI.
Horn: An optical element used to mix the light rays to improve the uniformity of
Driver: The electronics used for lighting energy sources
Efficacy (luminous efficacy): The output of light from a light source divided by the total electrical power of entry to the source expressed in lumens per watt (lm / W)
Epoxy: organic polymers frequently used in a dome or lens, often prone to optical decay over time, resulting in poor maintenance light.
Sources of high-power light does not contain epoxy and deliver higher light maintenance.
Flux: The sum of all lumens (lm) emitted by a source of
InGaN LED: The preferred LED semiconductor technology with indium, gallium and nitrogen, to produce green, white and blue color LED light sources
Kelvin: Term and symbol (K) used to indicate the comparative color appearance of a light source compared to a
theoretical black. Incandescent are yellowish 3000K. Fluorescent light sources ranging from 3000K to 7500K and above.
Lumen (lm): The international unit (SI) of luminous flux or the amount of light. It is equal to the amount of light that extends about 929 sq.cm
surface by one candle when all parts of the surface are exactly 30 cm from the source of light. For example, a dinner candle provides
about 12 lumens. 60W incandescent lamp provides 840 lumens white light.
Lumen maintenance: The percentage of flow remaining in the expected life of a light source
Conservation of flow light curve: a graph comparing the loss of light output against time the light source is used
Luminaire: complete luminaires installed lamps and other accessories
Lux (lx): The SI unit of illuminance or luminous flux incident on a unit surface-often defined as one lumen per square meter (lm/m2)
Metameric: The term used to describe the phenomenon of visual perception in which spectrally different sources of mixing in a chroma third. For example, Sir Isaac Newton discovered that white people perceive when observing light blue and yellow mixed.
Nits: Measuring the brightness of the display. 1 nit = 1 cd/m2. The more nits, the brighter the image.
NTSC color space: The range of colors within the CIE chromaticity diagram including when combined sources RGB phosphor
Such as cathode ray tube televisions and computer monitors
Planckian black body Held Line in the CIE chromaticity diagram, which describes the color temperature of an object when it is heated from about 1000K to over 10,000 K
Warm White light with a correlated color temperature between 3000K and 3500K, typically perceived as slightly yellow.
Point blank: Coordination Color Temperature (CCT), defined by a line perpendicular to the curve of the Planckian black body and cut
measured chromaticity
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