Advantages of LED
The advantages of LED lighting over traditional light sources are numerous:
Tungsten or Halogen sources produce light as a result of an electric current heating a filament within the light source. Unfortunately, this lighting process is inefficient because most of the current is not transformed into light but transformed into heat instead. Due to the intense heat of the filament, the lifetime of Tungsten or Halogen is very short, averaging between 1,000 to 2,000 hours. Tungsten and Halogen lights are the most easily replaceable by LED products because LED lighting can match most Tungsten or Halogen on a one to one basis. This is GREEN CREATIVE’s primary retrofit target.
Another commonly used lighting source is fluorescent, where mercury atoms are excited by an electric arc. The result is the emissions of ultra violet radiation that hit a phosphor coating inside a tube to produce light. This form of lighting is more efficient than halogen or incandescent, however, the main drawback of this source is the hazardous material content, the low resistance to switching cycles, limited efficiency, slow starting time, and shorter lifetime than LED.
The biggest issue with fluorescent lighting products is that they emit light in all directions resulting in most of the light to be lost within the fixture. Therefore, fluorescent cannot replace halogen PAR or MR type sources where high light intensity is needed. The LED chip on the other hand emits light in only one direction, maximizing the amount of useful light for each application.
Currently, the only drawback for LED is the initial investment. However, the electricity and maintenance cost savings offer an average ROI below 12 months (See ROI section). This payback period excludes utility rebates that are applicable for our products. (See Utility Rebate section).
LED (Light Emitting Diode) is a semiconductor diode. The chip or die consists of different layers of semiconducting materials. When the current is applied, a positive layer of electrons meets a negative layer with holes at a junction (Fig. A). When an electron takes the place of a hole it drops to a lower energy level (Fig. B) releasing energy in the form of a light photon (Fig. C). This process of creating light is known as Electroluminescence.
Different semiconductor materials emit different color of light. White LEDs used in our product are created by adding a phosphor coating on a blue LED chip.
LED Package Composition
The LED chip or die cannot be used independently but must be packaged into a lighting system before it can be used in an application. When referring to LED lighting, we usually refer to the LED package.
The main package components are:
The LED package can be manufactured by the chip manufacturer or by a third party packaging company such as Dominant in Malaysia, Edison in Taiwan or hundreds of smaller ones mainly located in China.
The advantages of a full package by a chip manufacturer over a third party package:
Thus, for very demanding commercial applications where high performance and longer lifetime is required, a full package from a chip manufacturer will be used. All GREEN CREATIVE products use full package from chip manufacturer.
There are thousands of LED packages that come in different shapes, power and size. However, we can distinguish three main LED types: 5mm LED, SMD Low Power LED and SMD High or Medium Power LED.
THT – Through Hole Technology LED(Fig. A): The component wire leads or “legs” goes through a hole in the PCB and is soldered at the back. THT LED, also known as 5mm LED, is the earliest type of LED that was integrated in electronic devices. It is the cheapest LED available but offers very limited lighting output and fast lumen depreciation.
SMD – Surface Mount Device LED(Fig. B): The component is soldered on the surface of the PCB allowing for better heat dissipation and higher component density. Both side of the PCB can also be used, reducing the PCB’s overall size. Assembly of SMD LED is automated using an SMT (Surface Mount Technology) assembly line for better productivity and quality control.
GREEN CREATIVE exclusively uses SMD Medium and High Power LED which offers both high performance and longevity needed for demanding lighting applications.
White LEDs are formed when a blue LED chip is covered with a layer of phosphor during the packaging process. The tiniest variation in the phosphor layer and packaging assembly will lead to different color temperature and brightness.
Currently, creating a batch of LEDs at a uniform color temperature and brightness is a big challenge because it is not possible to perfectly control LED properties during mass production. Thus, the binning of LEDs is a practice used by LED manufacturers to manage the variation of LED performance and color at the end of the mass production process.
Each LED will be automatically sorted in a different bin based on its brightness and color temperature (See Luxeon bin structure example). It is then up to the lighting manufacturer to select the bins according to its needs. GREEN CREATIVE uses a tight binning selection for each LED type to ensure consistent color and brightness of each batch.
Thanks to the invention of the white LED and the enhanced lighting output improvement, LED lighting has become a relevant alternative to traditional lighting sources such as incandescent and halogen.
The “Haitz law” based on observations of Roland Haitz is the LED equivalent of the “Moore’s law” for transistors in IC. It shows that for every 10 years, LED package lighting output will increase by a factor of 20 while the cost per lumen will drop by a factor of 10.
In order to take advantage of such improvement in lighting performance and costing, LED lighting manufacturers must master a specific set of competencies and processes (see LED competencies section).