LED Lighting Basics

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General Lighting Parameters

Time: 2020-04-09

This article is written for those involved in the lighting environment, including lighting designers, architects, engineers, and lighting equipment manufacturers.


Here are some general lighting terms that most people in the commercial, institutional and uyility industry need to know.


COB (chips on board)


COB (chips on board) is an LED packing technology used for LED light engines. 


Multiple LED chips are packed together on LED substrate boards. There is cooper boards, aluminum boards, ceramic boards and so on. Among these options, the chip on the ceramic board LED has better performance in terms of lighting efficiency and luminance reduction.


The size of the board can range from mini meters to a couple of centimeters, which depends on the capabilities of the development company.


(Click here for Detailed Explanation)



SMD


Surface-mount technology LEDs is the most concerned LEDs in the market. Usually installed in different sharp PCBs to fit different lamps or devices.

 

Typical SMD models are 2828, 3535, and 5050. For example, 2828 indicates that the width of the SMD is 2.8mm and the height is 2.8mm.


 

Color Rendering Index


Sometimes the lights wil tell lies. The color of the objects in the outdoors is different from indoors. That's because lights have different capabilities in color renditions.


Color Rendering Index, also called as CRI, is a measurement of the ability of color renditions. CRI simply rates maximum to 100, and the higher the index, the better the color rendering.


For nomal lighting projects, the outdoor CRI range is RA70 to RA80, while the indoor CRI is RA85 to RA90.But for special places, such as showrooms, printing workshops, or any places that require high color renditions, the CRI index can reach RA95 to RA98 or higher.


(Click here for Detailed Explanation)


 

Color Temperature


Color temperature is a measure of how warm or cold the light emitted by the lamp is. The way to measure light is through the Kelvin Temperature scale.


Warm colors appear tinged with yellow and generally feel soft and cozy. And cool colors are tinged with blue and appear whiter, making them a more ‘honest’ and unforgiving light, which is more suitable for working environments than relaxing. 


 

 

Lighting Efficacy


Lighting Efficiency is a metric used to compare the ratio of light output to energy consumption. The unit is lumens per watt. Higher lighting efficaciency means more energy saving and is a power-saving performance.


The lighting efficiency of normal light sources can reach 140lm/w to 160lm/w, while the lighting efficiency of some outstanding models can exceed 180lm/w, which is far away from other lighting equipment.


However, when the light source is installed on the led lamp, the lighting efficiency will decrease because when the lighting passes through the lens, the lighting power will be consumed and absorbed by the metal body.That is why street lamps always use LED light sources.

Lumen


Lumen, the unit of light flow. The lumen rating of a lamp is a measure of the total light output of the lamp. It is used to describe the ability of the light source radiation to produce a strong or weak visual response per unit time. The unit is lumen, also called brightness.


Approximate lumens of common lamps (lumens / watt): 


* Incandescent lamp, 15

* White LED, 80-200

* Fluorescent lamp, 50

* Sun light, 94

*Sodium lamp, 120

*Energy-saving lamps, 60-80

*LED, 80-130


* Please note that these lumens are approximate and may vary due to different manufacturers.




Lux


Lux is the unit of illuminance, which indicates how much light is incident on the surface. One lux is defined as an illuminance generated when one lumen is incident on one square meter area, so one Lux is one Lumen per square meter area.


The illuminance on a bright days is 100,000 lux. The football game broadcast on television requires an illuminance of about 16,000 lux. The kitchen needs about 500 lux. Public roads at night require about 30 lux.




Illuminance


The degree of illumination required by the surface depends mainly on the type or nature of the jobs or human activity on the illuminated surface.


Therefore, step 1 is to determine how much illumination is needed. Type of task, duration of usage, age and number of people working in the area, precision level of the work, and available natural lights are all factors that determine the illuminance requirements.


Step 2 is to determine the number and type of light sources needed to produce the desired luminance. Three main factors must be considered.


* The type of the Light source: cost, color and life of the light source are the main determinants of the light source type.


* The incident light energy follows the square law. The illuminance on the surface is proportional to the square of the distance, which makes the distance from the light source an important factor.


*The co-efficient of utilization is also a factor that determines how much of the luminous flux actually comes from the light source on the desired surface. Reflectors, lampshades and  luminaires can increase or decrease utilization. The utilization rate of good industrial lamps can reach 90%.


 


LED Array or Module


In the assembly of LED package (components) or dies on a printed circuit or substrate, the optical element may have additional thermal, mechanical, and used to connect an electrical load to the LED drive interface side. The device has no power supply and standard lamps. The device cannot be directly connected to the branch circuit.


It may carry optical components and other thermal, mechanical, and electrical interfaces that are intended to connect to the load side of the LED driver.


 

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