Look for
Lumens
Most of us associate the brightness of electric light with the wattage of
the familiar incandescent, pear-shaped bulb. You may know, for example,
that a standard incandescent 60-watt bulb provides the right level of
light in that lamp next to your bed, so that's what you buy every time the
bulb burns out. But you will get even greater light output from an 18-watt
compact fluorescent. It's the light output you really want--and that is
measured in lumens, not watts.Lighting manufacturers
must now label packaging with the number of lumens as well as the number
of watts. It may take some adjustment at first, but look for the number of
lumens you are getting per watt. Both the 60-watt incandescent and the
18-watt fluorescent give off about 1000 lumens. But the incandescent
produces only 15 lumens per watt, while the fluorescent produces over 50
lumens per watt. It's not hard to tell which one is more efficient. A good
rule of thumb is to choose a compact fluorescent that is about one-third
the wattage of the incandescent you would normally buy.
Don't mistake compact fluorescents for the reduced
wattage incandescent "energy savers" that are on store shelves everywhere.
These bulbs simply give you less light output. In comparison shopping,
look for the lumens you want; then choose the bulb with the lowest
wattage.
Judging Quality
While the number of lumens tells you how much light you are getting, it
tells you nothing about the quality of that light. When it comes to
quality, one big concern is color. Natural light is the standard by which
all artificial lighting is measured. Colors can look much different in
daylight than they do under some electric lights. You've probably
discovered this after buying clothing in a store only to find that once
outside, the color seemed to change.
There are two numbers that tell us approximately what a
light will look like when it's turned on. The color rendering index, or
CRI, is measured on a scale of 1 to 100, where 100 represents how colors
look in daylight. The higher the number, the more accurately the
artificial light will render colors.
The other number measures color temperature. This lets
you know whether the light will have more of a reddish (warm) or a
blue-white (cool) hue. Color temperature is measured on the Kelvin scale
where the "cooler" the light, the higher the temperature (just the
opposite of the Fahrenheit scale). Warm lights are below 3,100 K and cool
lights are over 4,000 K; 3,500 K is considered neutral.
Standard incandescent lights, like the 60-watt bulb
mentioned above, have a CRI of 95+ and a color temperature of 2,700 K.
Fluorescent lights vary because the type of phosphor that coats the inside
of a fluorescent determines its color characteristics. A typical 18-watt
compact fluorescent replacement for that bedside lamp would have a CRI of
82 and a color temperature of 2,700 K.
Light distribution is another measure of quality. This
is determined by the shape of the light bulb, any reflective coatings, and
the type of fixture. The distribution pattern is important in directing
light to the area where it is needed. For example, a ceiling fixture meant
to provide ambient lighting to a whole room would be designed to produce a
smooth, broad distribution pattern. It would be very different from a
fixture used to highlight a painting in the room. Likewise, the light
bulbs used in the fixtures should be different: a diffuse, nondirectional
bulb would be best for general visibility, and a bulb that casts a
directional beam, such as a reflector light, would be more suitable for
accenting the art.
What IS .... LED Definitions
These definitions have been written in a form that is easy to understand,
and only as they relate to LEDs. We hope that you will find these
definitions easy to apply towards any LED product described on our web
site and understand what we have stated for those products. We would
welcome any comment, correction or addition to these words and definitions
by emailing us at Sales@theledlight.com. Please - do not be
counter-productive by suggesting actual word for word definitions found
elsewhere.
Amperage: The strength of an electrical current measured in amperes. The
higher the amperage number, the higher the ability to place more devices
on a circuit that will be driven by that amperage.
Amp: The basic unit of electric current adopted under the System
International d'Unites; "a typical household circuit carries 15 to 50
amps"
Bulb: It is not a LED. A bulb is a light bulb, a flashlight bulb, a MR16
or E27 light bulb. A LED light bulb is a finished product that has the
LEDs installed, electrical components installed and is ready to be used by
the consumer. A LED light bulb is screwed in place, twisted and locked in
place, pressed into sockets or contact terminals. This is a LED bulb.
Bulb Base: The part of the bulb that is used to set it into place and to
make contact with electricity. There are many types and sizes. Most common
are E26/27, USA and European standard household size, or medium base as it
often is called. The 26 or 27 equates to the diameter measurement in
millimeters of the threads of a screw-in bulb base. This type of bulb also
includes the PAR 20, PAR 30 and PAR38 types, and a few others. There are
MR16 and MR11 type base LED bulbs as well as GU10s.
Chromaticity: Chromaticity tells you what the lamp itself or a neutral
surface illuminated by a lamp will look like. Chromaticity sets the "tone"
or atmosphere of a room: warm, cool or something in between. Chromaticity
(sometimes called color temperature) is usually measured in Kelvin. It can
also be defined by using x and y coordinated against a standard
chromaticity scale developed by the Commission Internationale de
l'Éclairage (CIE). Here is a Chromaticity Graph that is commonly used.
Color Rendering Index (CRI): Also CCT or Correlated Color Temperature. It
is a measure of the quality of light. It is a measurement of the amount of
color shift that objects undergo when lighted by a light source as
compared with the color of those same objects when seen under a reference
light source of comparable color temperature. LED light CRI values
generally range from 60 (average) to 90 (best). High CRI equates to
sharper, crisper, more natural colored pictures while at the same time
reducing glare.
Color Temperature: A measure of the color of a light source relative to a
black body at a particular temperature expressed in degrees Kelvin (K).
Incandescent lights have a low color temperature (approximately 2800K) and
have a red-yellowish tone; daylight has a high color temperature
(approximately 6000K) and appears bluish (the most popular fluorescent
light, Cool White, is rated at 4100K). Lamps with color temperatures below
5000K tend to be more yellow/red, lamps rated between 5000 and 6000K are
viewed as white, while lamps above 6000K tend to have a blue cast.
Dimmer: 12vdc only. Used with LED lights powered by 12vdc - never
110/120vac. PWM built-in, as is an On/Off Switch. Will dim majority of
12vdc LED lights and a few 12vdc LED bulbs such as MR16s with the proper
transformer/power supply. Dimmers are part of our LED control products.
Foot-Candle: The unit is defined as the amount of illumination the inside
surface of an imaginary 1-foot radius sphere would be receiving if there
were a uniform point source of one candela in the exact center of the
sphere. Basically, it is the amount of light that a single candle would
provide to a 1ft. radius sphere.
Full Spectrum: A light bulb or lamp that produces a light spectrum that
covers the entire range of visible light (400-700nm) without gaps in its
spectral output. White LEDs are inherently a full spectrum light source.
Intensity: Is a measure of the time-averaged energy flux or amount of
light striking a given area. For bulbs alone this is measured in terms of
lumens while for lighting fixtures it is measured in lux (lumens/sq.
meter).
Kelvin Color Temperature: A measure of the color of a light source
relative to a black body at a particular temperature expressed in degrees
Kelvin (K). Incandescent lights have a low color temperature
(approximately 2800K) and have a red-yellowish tone; daylight has a high
color temperature (approximately 6000K) and appears bluish (the most
popular fluorescent light, Cool White, is rated at 4100K). Today, the
phosphors used in fluorescent lamps can be blended to provide any desired
color temperature in the range from 2800K to 6000K. Lamps with color
temperatures below 5000K tend to be more yellow/red, lamps rated between
5000 and 6000K are viewed as white, while lamps above 6000K tend to have a
blue cast.
L.E.D.: LED means light emitting diode. LEDs are a solid state device and
do not require heating of a filament to create light. Rather, electricity
is passed through a chemical compound that is excited and as a result,
generates light.
LEDs are not bulbs or lamps in the true sense of the word and application.
LEDs require a lot of work to make them ready to be used by the consumer.
They need to be placed on a circuit board or other material which will
allow electricity to pass through it at a specific voltage and current,
and with components required to operate them at specific voltages such as
12vdc, 24vdc or 120vac. They do not come ready to plug into a 12volt or
120 volt power source. These are LEDs.
LED Bar: Refers to a solid strip of material on which LEDs have been
soldered, along with resistors and other components which a specific
product requires to make it operate at the stated operating voltage. The
Bars are usually an enclosed strip of LEDs. Enclosures are plastic, or
aluminum, or metal composites with various types of lens/cover plates.
LED Cluster or Array: A group of LEDs set in a square, rectangular or
linear pattern, and formatted to be operated at a specific voltage. They
will always include two wires called leads. One is positive, the other
negative.
LED Drivers: are current control devices which replace the need for
resistors. LED Drivers respond to the changing needs of a LED or a LED
circuit, and supply a constant amount of power to the LED as its
electrical properties change with temperature.
LED Lighting: A general term used by those who do not know the specific
type or category of LED lighting they are after. LED lighting includes LED
bulbs and fixtures, flashlights, strips, clusters and other LED light
sources.
LED Strip: LED Strips are usually printed circuit boards with LEDs
soldered to the board. The strip can be rigid, or flexible and without any
enclosure to protect the LED and circuit.
Low Voltage: With LEDs, that means 12vDC 24vDC or 48vDC, as opposed to
110/120vac which is high voltage. With LEDs, low voltage is commonly
12vdc; sometimes at 24vdc. To run these low voltage lights, power will
have to be sent to the light through a power supply/transformer/adapter
that is hooked up to 110/120/240vac power lines. The actual voltage
reaching the light will be at 12vdc.
Lumen Maintenance: How well a LED light bulb is able to retain its
intensity when compared to new. Typically a high power smd LED bulb will
retain 70% of its intensity for 40,000-50,000 hours. That means a good
quality LED bulb will run 8 hours a day for 13 years at 70% of its new
condition. No other light source can do this.
Lumens: The unit of luminous flux in the International System, equal to
the amount of light given out through a solid angle by a source of one
candela intensity radiating equally in all directions. Used to measure
light bulbs as stand alone light sources. Lighting fixtures are measured
by lux output which is lumens per square meter.
Lux: Typically used to measure the light intensity produced by a lighting
fixture. The higher the lux reading the more light the lighting fixture is
producing over a given area. Known as lumens per square meter
mA: stands for milliamp. 1000mA equals 1.0 amp. All LEDs run on current
and current is measured in milliamps. All LED products have a mA rating at
which they are to be powered at.
MCD: or Millicandela, is used to rank/denote the brightness of a LED.
1000mcd is equal to one Candela. The higher the mcd number, the brighter
the light the LED emits.
Nanometers: or nm. Used to measure the wavelength of light. The lower the
wavelength for example, 400nm, the bluer and stronger the light source.
Longer wavelengths above 600nm are red. Above 680nm, they fall into the
InfraRed category, which is colorless to our eyes. White LEDs have no
specific wavelength. They are measured by the color of white against the
chromaticity scale.
PCB/Printed Circuit Board: are made from various materials including
fiberglass and aluminum. The pcb has an electrical circuit imprinted in
silver etching. That circuit says how the LED will operate. The pcb is
also the platform by which LEDs are employed in various applications. It
can be a rigid board or flexible to twistable.
Power Supply: and Transformer and Voltage adapter apply to the electrical
conversion of 110/120/240vac line power into 12vdc which will then be
applied directly to the LED light product. Power Supplies are rated
according to the current/amperage load capacity each will handle. It is an
electrical or electro-mechanical device.
PWM: Pulse Width Modulation with regards to LEDs means that the LED will
be pulsed or strobed at a rate so fast that the eye will see the light as
being constantly on. In fact it is not. This pulsing or turning the LED on
and off lowers the potential heat stress on the chemical that makes the
light, thus allowing the LED to perform longer than anticipated. This is
why we strongly recommend a dimmer/PWM with every purchase of a 12vdc LED
product.
RGB: RGB stands for Red, Blue, Green, the 3 primary colors that make white
light and all other colors. It can be a pre-programmed 7 color
automatically changing LED bar or strip that is non-adjustable. It also
means a RGB color changing system that allow adjustment of color change
frequency, strobing, chasing and other action modes.
SMD/SMT: A type of low profile LED that is surface mounted to a PCB. These
type LEDs are very powerful and range in lumen output from 35 up to 170
lumens. With the latest LED technology being applied today, these have
shown to have the most promise in delivering light levels and coloring
that we are used to having. Those smd LEDs we talk about, use and sell are
in the .5 watt, 1 watt, 3 watt and 5 watt power range. When you see a 7
watt or 9 watt LED light, it will contain 1 watt LEDs x 7, or 1 watt LEDs
x 9, or 3 watt LEDs x 3.
SSL: SSL means Solid State Lighting. It does not use heating of a thin
fragile filament to create light. Rather, it uses electrical current
passing through a chemical which will get excited and thus emit light.
Task Lighting/Lamp: A LED light used to specifically light a particular
area used for work or reading. Typically found in the form of a desk,
floor, or clamp-on lamp, it can be a high powered LED light in any form.
UV-A: (380–315 nm), also called Long Wave or "blacklight" because it is
invisible to the human eye. Can cause skin irritation and fading of
fabrics.
UV-B: (315–280 nm), also called Medium Wave radiation. Can cause severe
damage to the skin and human eye through exposure.
UV-C: (← 280 nm), also called Short Wave or "germicidal" for its ability
to destroy even bacterial life forms. Extremely hazardous to all life
forms due to its ability to cause immediate damage to cellular DNA.
View Angle Degree: Also referred to as directivity, or the directional
pattern of a LED light beam. The expressed degree dictates the width of
the light beam and also controls to some extent, the light intensity of a
LED. View angles range from 8 to 160 degrees, and are provided through the
use of optics, special lenses made to collimate light to into a desired
veiw angle.
Voltage: The rate at which energy is drawn from a source that produces a
flow of electricity (amperage) in a circuit. The difference in electrical
charge between two points in a circuit is expressed as volts.
Voltage Regulator: A device which limits or controls and stabilizes the
voltage being applied to a using unit such as LED lights and motors.
Regulators also take higher voltages than required and reduces it to the
working voltage that makes a specific product run correctly. In many
instances a lack of a Voltage Regulator will allow higher voltage than a
product can work with and will cause irreparable damage.
Volts: The International System unit of electric potential and
electromotive force, equal to the difference of electric potential between
two points on a conducting wire carrying a constant current of one ampere
when the power dissipated between the points is one watt.
Waterproof: meaning the LED product can be submerged into calm water but
there is a limited depth as stated for each specific product. Most
aluminum bodied LED products will not do well in salt or acidic water.
Watts: The unit for measuring electrical power. It defines the rate of
energy consumption by an electrical device when it is in operation. The
energy cost of operating an electrical device is calculated as its wattage
times the hours of use. In single phase circuits, it is related to volts
and amps by the formula: Volts x Amps x PowerFactor = Watts.
Watt per LED: It can be confusing when two watt numbers are used in
product specifications. For the application to smd high powered LEDs, the
1 watt, 3 watt, 5 watt, etc, refers to the power consumption of that
specific LED installed in that product. The watt numbers expressed as
light output are a comparison to an incandescent light bulb light output,
for example; a 60 watt light output is equal to a 60 watt incandescent
light bulb.
Weatherproof: meaning the product will take water splashing and high
humidity without deterioration to the LED or circuit. LED product cannot
be submerged into water.
White: White is defined by Kelvin Temperature or Degrees Kelvin. Most will
say that a Kelvin Temperature of 6000k plus is white with a bluish tint.
And let's say that 5000k -5500k is daylight/sunlight white. At
4200k-4500k, it is called cool white. At 2800-3300k, it's warm white,
which is the color temperature most incandescent light bulbs emit.
From 5500k on down the scale, the color becomes "warmer" due to the
dominance of red and yellow hues. In the opposite direction, whites will
have cooler colors like blues and green becoming more apparent, thus they
are called cool whites.
