Brightness:

The output intensity or brightness of an LED is measured in millicandela. The most common technique used in indoor displays to get the greatest range of brightness is called “multiplexing”. The LED’s are strobed rapidly, faster than the eye can detect, one at a time. This method limits the brightness of each pixel since the pixel is only turned on for a sequence of brief instances. When an LED is latched on, it lighted continuously until it is turned off again. This produces brighter pixels. Data block modules can only be multiplexed; discrete clusters re usually latched.

 

CCT:

See Correlated Color Temperature.

 

Color Temperature:

The description use to describe the effect of heating an object until glows incandescently, the emitted radiation, and apparent color, changes proportional to the temperature; easily envisioned when considering hot metal in a forge that glows red, then orange, and then white as the temperature increases. 2. 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 with, while lamps above 6000K tend to have a blue cast.

 

Correlated Color Temperature (CCT):

The absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source. Usually specified in kelvin (K). the lower kelvin temperature, the warmer the light feels, or appears. 2. The measure used to describe the relative color appearance of a white light source. CCT indicates whether a light source appears more yellow/gold/orange or more blue, in terms of the range of available shades of “white.” CCT is given in kelvins (unit of absolute temperature).

 

Cost of Light:

Usually refers to the cost of operating and maintaining a lighting system on an ongoing basis. The 88-8-4 rule states that (typically) 88% is the cost of electricity, 8% is labor and only 4% is the cost of lamps.

 

Dimmer, Dimming Control:

A device used to lower the light output of a source, usually by reducing the wattage it is being operated at. Dimming controls are increasing in popularity as a energy conserving devices.

 

Efficacy:

the light output source divided by the electrical power input to that source, expressed in lumens per watt (lm/W)

 

Kelvin Temperature:

term and symbol (K) used to indicate the comparative color appearance of a light source when compared to a theoretical blackbody. Yellowish incandescent lamps are 30000K. Fluorescent light source range from 3000K to 7500K and higher. The color measurement for white light. The higher the number, the more blue (i.e. 7000K) the white will appear and the lower the number (i.e. 3200K) the warmer the light will appear. This is important if, as an example you have a set of halo/ reverse channel letter mounted on a white background. A 5500K to 6500K is typically preferred and is the more common K color of most LED. On the other hand if you have the same letters on a wood background, a warmer LED chip in the 2800K to 3500K would give a nice warm illumination making the wood background look very nice.

 

LED:

See Light Emitting Diode.

 

Lens:

A transparent or semi-transparent element which controls the distribution of light by redirecting individual rays. Luminaires often have lenses in addition to reflectors.

 

Light:

Radiant energy that can be sensed or seen by the human eye. Visible light measured in lumens.

 

Light Output:

See luminous flux.

 

LM80:

Light depreciation over time – test LED chip at 6,000 hours.

 

L70:

30% light loss in 70,000 hours (shorthand for lumen depreciation to 70% of initial lumen output, it indicates 70% of lumen maintenance).

 

Lumen (Lm):

The international (SI) unit of luminous flux or quantity of light and equals the amount of light that is spread over a square foot of surface by one candle power when all parts of the surface are exactly one foot from the light source. For example, a dinner candle provides about 12 lumens.

 

Lumens per Watt:

In SI, luminous efficacy has units of lumens per watt (lm/W). Photopic luminous efficacy has a maximum possible value of 683 lm/W, for the case of monochromatic light at a wavelength of 555nm (green).

 

Lumen Output:

The total lumens emitted of a light source, system, or solution.

 

Luminaire:

A lighting fixture complete with installed lamps and other accessories.

 

Power Dissipation:

Amount of heat energy generated by a device in one second when current flows through it.

 

Power Factor:

The active power divided by the apparent power (i.e., product of the rms input voltage and rms input current of a driver).

 

Starting Temperature (Minimum):

The minimum ambient temperature at which the lamp will start reliably.

 

Useful life:

The amount of light a lighting fixture delivers in an application, minus any wasted light.

 

Voltage (V):

Term used to designate electrical pressure or force that causes current to flow.

 

Watt:

The unit of electrical power as used by an electrical device during its operation. Many lamps come with rating in watts to indicate their power consumption. 2. The unit for measurement od Metrical power; the energy required to light the product. The lower the wattage, the less energy is used. It defines the rate of energy consumption by an electrical device when it is in operation. The energy cost of operating and 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.