Types of Lighting Technologies

7/29/2019 Types of Lighting Technologies

1/9

Types of Lighting

technologies

Atul Anand Jha

Gaurav Dixit

B.Arch.-II (B)


2/9

Incandescent light bulb

Incandescent bulbs are manufactured in a wide range of sizes,

light output, and voltage ratings, from 1.5 volts to about 300

volts. They require no external regulating equipment, have lowmanufacturing costs, and work equally well on either

alternating current or direct current. As a result, the

incandescent lamp is widely used in household and commercial

lighting, for portable lighting such as table lamps,

car headlamps, and flashlights, and for decorative and

advertising lighting.

Some applications ofthe incandescent bulb use the heat

generated by the filament, such as incubators, brooding boxes

for poultry, heat lights for reptile-tanks.

The incandescent light bulb, incandescent lamp or incandescent light

globe produces light by heating a filament wire to a high temperature until

it glows. The hot filament is protected from oxidation in the air with a glassenclosure that is filled with inert gas or evacuated. The light bulb is supplied with

electrical current by feed-through terminals or wires embedded in the glass. Most

bulbs are used in a socket which provides mechanical support and electrical

connections.
http://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.pnghttp://en.wikipedia.org/wiki/File:Gluehlampe_01_KMJ.png


3/9

Halogen lamp

A halogen lamp, also known as a tungsten halogen lamp, is

an incandescent lamp with a tungsten filament containedwithin an inert gas and a small amount of a halogen such as

iodine or bromine.

The combination of the halogen gas and the tungsten

filament produces a chemical reaction known as a halogen

cycle which increases the lifetime of the filament and

prevents darkening of the bulb by redepositing tungsten

from the inside of the bulb back onto the filament. Because

of this, a halogen lamp can be operated at a higher

temperature than a standard gas-filled lamp of similar power

and operating life.

The tungsten filament in a halogen lamp is enclosed inside a

much smaller quartz envelope. Because the envelope is so

close to the filament, it would melt if it were made fromglass.

The higher operating temperature results in light of a higher

color temperature. This, in turn, gives it a higher luminous

efficacy (1030 lm/W).

Because of their smaller size, halogen lamps can

advantageously be used with optical systems that are more

efficient in how they cast emitted light.


4/9

Arc lamp "Arc lamp" or "arc light" is the general term for a class of lamps

that produce light by an electric arc (also called a voltaic arc).

The lamp consists of two electrodes, first made from carbon buttypically made today of tungsten, which are separated by a gas. The

type of lamp is often named by the gas contained in the bulb;

including neon, argon,xenon, krypton, sodium, metal halide, and

mercury, or by the type of electrode as in carbon-arc lamps.

The common fluorescent lamp is actually a low-pressure mercury

arc lamp

The electric arc in an arc lamp consists of gas, which is

initially ionized by a high voltage and therefore becomes electrically

conductive. To start an arc lamp, a very high voltage is pulsed across

the lamp to "ignite" or "strike" the arc across the gas.

The colour of the light emitted by the lamp changes as its

electrical characteristics change with temperature andtime. Lightning is a similar principle where the atmosphere is

ionized by the high potential difference (voltage) between earth

and storm clouds.


5/9

Metal-halide lamp

Metal-halide lamps, a member of the high-intensity discharge (HID) family of

lamps (which produces light by means of an electric arc

between tungsten electrodes housed inside a translucent or transparent fusedquartz or fused alumina arc tube.), produce high light output for their size,

making them a compact, powerful, and efficient light source.

By adding rare earth metal salts to the mercury vapor lamp,

improved luminous efficacy and light color is obtained. Originally created in

the late 1960s for industrial use, metal-halide lamps are now available in

numerous sizes and configurations for commercial and residential applications.

Like most HID lamps, metal halide lamps operate under high pressure andtemperature, and require special fixtures to operate safely.

Since the lamp is small compared to a fluorescent or incandescent lamp of the

same light level, relatively small reflective luminaires can be used to direct the

light for different applications (flood lighting outdoors, or lighting for

warehouses or industrial buildings).

Metal halide lamps are used both for general lighting purposes, and for veryspecific applications which require specific UV or blue-frequency light. Due to

their wide spectrum, they are used for indoor growing applications, in athletic

facilities and are quite popular with reef aquarists, who need a high intensity

light source for their corals.

Since a metal halide lamp contains gases at a significant high pressure, failure of the arc tube, is inevitably a

violent event. If the fixture has no secondary containment (e.g. a lens, bowl or shield) then the extremely hot

pieces of debris will fall down onto people and property below the light.

A typical lamp lasts from 6000-20,000 hours.

Efficacy 80 lumen/Watt

Color rendering index 1A 2

Color temperature: 3000 6000 K


6/9

Mercury-vapor lamp

A mercury-vapor lamp is a gas discharge lamp that uses an electric arc

through vaporized mercury to produce light.

The arc discharge is generally confined to a small fused quartz arc tube

mounted within a larger borosilicate glass bulb. The outer bulb may be clear

or coated with a phosphor; in either case, the outer bulb provides thermal

insulation, protection from the ultraviolet radiation the light produces, and a

convenient mounting for the fused quartz arc tube.

Mercury vapor lamps (and their relatives) are more energy efficient than

incandescent and most fluorescent lights, with luminous efficacies of 35to 65 lumens/watt. Their other advantages are a long bulb lifetime in

the range of 24,000 hours and a high intensity, clear white light output.

For these reasons, they are used for large area overhead lighting, such as

in factories, warehouses, and sports arenas as well as for streetlights

Clear mercury lamps produce white light with a bluish-green tint due to

mercury's combination of spectral lines. This is not flattering to humanskin color, so such lamps are not used in retail stores. "Color corrected"

mercury bulbs overcome this problem with a phosphor on the inside of

the outer bulb that emits white light. They offer better color rendition

than the more efficient high or low-pressure sodium vapor lamps.

Lamp life: 16000 24000 hours


7/9

Sodium-vapor lamp

A sodium vapor lamp is a gas discharge lamp that uses sodium in an excited state to

produce light. There are two varieties of such lamps: low pressure and high

pressure. Because sodium vapor lamps cause less light pollution than mercury-

vapor lamps, many cities that have large astronomical observatories employ them.

Low-pressure sodium (LPS) lamps have a borosilicate glass gas discharge tube

(arc tube) containing solid sodium, small amount of neon, and argon gas in a

Penning mixture to start the gas discharge. The discharge tube may be linear

(SLI lamp) or U-shaped. When the lamp is turned on it emits a dim red/pink

light to warm the sodium metal and within a few minutes it turns into the

common bright yellow as the sodium metal vaporizes.

These lamps produce a virtually monochromatic light averaging a 589.3 nm

wavelength (actually two dominant spectral lines very close together at 589.0

and 589.6 nm). As a result, the colors of illuminated objects are not easily

distinguished because they are seen almost entirely by their reflection of this

narrow bandwidth yellow light.

LPS lamps are the most efficient electrically powered light source when

measured for photopic lighting conditionsup to 200 lm/W, primarily because

the output is light at a wavelength near the peak sensitivity of the human eyeHigh-pressure sodium (HPS) lamps are smaller and contain additional elements such

as mercury, and produce a dark pink glow when first struck, and a pinkish orange light

when warmed. Some bulbs also briefly produce a pure to bluish white light in between.

This is probably from the mercury glowing before the sodium is completely warmed. The

sodium D-line is the main source of light from the HPS lamp, and it is extremely pressure

broadened by the high sodium pressures in the lamp; because of this broadening and

the emissions from mercury, colors of objects under these lamps can be distinguished.

This leads them to be used in areas where good color rendering is important, or desired.

HIGH PRESSURE SODIUM BULB

OTHER DETAILS

Consist of: ballast, high- voltage

electronic starter, ceramic arc

tube, xenon gas filling, sodium,

mercury

No starting electrodes

High efficacy: 60 80

lumen/Watt

Color rendering index: 1 - 2

Lamp life < 24,000 hrs


8/9

Fluorescent lamp

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses

electricity to excite mercury vapor. The excited mercury atoms produce

short-wave ultraviolet light that then causes a phosphor to fluoresce,

producing visible light.

Lower energy cost typically offsets the higher initial cost of the lamp. The

lamp fixture is more costly because it requires a ballast to regulate the

current through the lamp.

While larger fluorescent lamps have been mostly used in commercial or

institutional buildings, the compact fluorescent lamp is now available in the

same popular sizes as incandescent and is used as an energy-saving

alternative in homes.

The fundamental means for conversion of electrical energy into radiant energy in a fluorescent lamp relies on

inelastic scattering of electrons. An incident electron collides with an atom in the gas. If the free electron has

enough kinetic energy, it transfers energy to the atom's outer electron, causing that electron to temporarilyjump up to a higher energy level.

This higher energy state is unstable, and the atom will emit an ultraviolet photon as the atom's electron reverts

to a lower, more stable, energy level. Most of the photons that are released from the mercury atoms have

wavelengths in the ultraviolet (UV) region of the spectrum, not visible to the human eye, so they must be

converted into visible light. This is done by making use of fluorescence. Ultraviolet photons are absorbed by

lamp's interior fluorescent coating, causing a similar energy jump, then drop, with emission of a further photon.

The chemicals that make up the phosphor are chosen so that these emitted photons are at wavelengths visible

to the human eye


9/9

Light-emitting diode

A light-emitting diode (LED) is a semiconductor light source. LEDs are

used as indicator lamps in many devices and are increasingly used for

other lighting. Introduced as a practical electronic component in 1962,

early LEDs emitted low-intensity red light, but modern versions areavailable across the visible, ultraviolet, and infrared wavelengths, with

very high brightness.

When a light-emitting diode is forward-biased (switched on), electrons are

able to recombine with electron holes within the device, releasing energy

in the form of photons. This effect is called electroluminescence and the

color of the light (corresponding to the energy of the photon) is

determined by the energy gap of the semiconductor.

LEDs are often small in area (less than 1 mm2), and integrated optical

components may be used to shape its radiation pattern. LEDs present

many advantages over incandescent light sources including lower

energy consumption, longer lifetime, improved robustness, smaller

size, and faster switching. LEDs powerful enough for room lighting are

relatively expensive and require more precise current and heat

management than compact fluorescent lamp sources of comparable

output.Light-emitting diodes are used in applications as diverse as aviation

lighting, automotive lighting, advertising, general lighting, and traffic

signals.

Types of Lighting Technologies

Documents

Transcript of Types of Lighting Technologies