LED lights technology

LED lights..what is it ?
Light emitting diodes, commonly called LED, are real unsung heroes in the electronics world. They do dozens of different jobs and are found in all kinds of devices. Among other things, they form numbers on digital clocks, transmit information from remote controls, light up watches and tell you when your appliances are turned on. Collected together, they can form images on a jumbo television screen or illuminate a traffic light.

Basically, LEDs are just tiny light bulbs that fit easily into an electrical circuit. But unlike ordinary incandescent bulbs, they don't have a filament that will burn out, and they don't get especially hot. They are illuminated solely by the movement of electrons in a semiconductor material, and they last just as long as a standard transistor. The lifespan of an LED surpasses the short life of an incandescent bulb by thousands of hours. Tiny LEDs are already replacing the tubes that light up LCD HDTVs to make dramatically thinner televisions.

In this article, we'll examine the technology behind these ubiquitous blinkers, illuminating some cool principles of electricity and light in the process.

While LED lighting has been used for years as power indicator lights in consumer electronics, for bike lights, in cars, in traffic lights and for outdoor lighting, recent technological advances mean LED light bulbs are entering our homes as a replacement for incandescent and fluorescent light bulbs. 

Why is LED lighting growing in popularity? What are the benefits of LED light bulbs? And what's actually inside an LED bulb? We have taken a look at this potentially exciting technology to give you the answers to these kind of questions, and more. 

What is an LED?

An LED is a "Light Emitting Diode," a type of semiconductor that can fit into an electronic circuit and carry an electrical current in one direction.

How do LED light bulbs work?

LEDs are made up of two types of material — N-type material and P-type material. The N-type material is engineered to contain extra electrons with extra charge. The P-type material has extra "holes" it wants filled with the charged electrons.

When the current is activated the electrons move from the negatively charged area to a positively charged area. This generates energy which is released as a "photons" — units of light.

 

What is the benefit of LED lighting?

While they currently cost more than ordinary bulbs, LED light bulbs can last 25 times longer than traditional bulbs. 

Traditional incandescent bulbs only convert around 10% of their energy output into light — wasting the other 90% as heat. LED bulbs lose very little energy in heat output and are approximately 400% more energy efficient. In addition, LED is a much brighter light. LED bulbs can offer better intensity than traditional bulbs, and can be programmed to produce millions of colors as well as different hues of white light.

What is LED lighting?

LED lights are the latest technology in energy efficient lighting. LED stands for ‘Light Emitting Diode’, a semiconductor device that converts electricity into light.

LED lights are super energy efficient, using approximately 85% less energy than halogen or incandescent lighting – meaning significant savings on your power bills. LED lights also have a much longer lifespan than other types of lighting - see the table below.

Lighting technology	Estimated lifespan*
LED	30,000-50,000 hours
CFL	8,000-15,000 hours
Halogen	1,000-5,000 hours
Incandescent	1,000 hours

*Depending on the globe

What are the other types of lighting?

Incandescent

Incandescent globes look like the traditional ‘Edison’ shaped light bulb, with a filament strung across two metal bars in the centre of the globe.

Due to government regulations, as of November 2009 you are no longer able to purchase standard incandescent globes. These globes were extremely inefficient because they only converted 5-10% of the energy they produced into light, while the remainder was converted to heat. The result was an extreme waste of electricity.

Halogen

Halogen globes will look similar to incandescent globes, but it uses an envelope filled with Halogen low pressure Halogen gas to help burn the filament to produce the visible light. In addition, regular 12 volt downlights that have not been changed to energy saving fittings are likely to be halogen.

Low-voltage halogen globes are the most commonly used light globes in Australia. However, they are a type of incandescent globe, so although they require lower voltages, they are not energy saving. In fact, each low-voltage halogen globe generates a kilogram of greenhouse gas every 15 hours, which is about the same as a standard 60 watt incandescent globe. Low voltage halogen downlights are connected directly to transformers and cannot be retrofitted with CFLs, but they can be with LEDs, making LEDs an ideal replacement for halogen downlights. Most of the LED downlights and LED globes on our website are replacements for halogen products.

Eco Halogen

Halogen globes will look similar to incandescent globes, but it uses an envelope filled with Halogen low pressure Halogen gas to help burn the filament to produce the visible light. In addition, regular 12 volt downlights that have not been changed to energy saving fittings are likely to be halogen.

These globes have typically replaced incandescent globes, for example in pendant lights, chandeliers and spotlights. Newer energy saving halogens – called eco-halogens – are now available and are about 30% more efficient than incandescent globes. All of the halogen globes you’ll find on our website are eco-halogens.

CFL (Compact Fluorescent Lamp)

CFLs are fluorescent tubes twisted into shape to fit a standard light fitting. CFLs are about 80% more efficient than incandescent globes but have some restrictions, such as dimming size and the appearance.

 

What's so different about LED lights?
First let's take a look at the traditional light bulb or "lamp" as it's called by the industry.

The light in most homes is produced by incandescent sources. The bulb structure is produced when hot glass is blown into molds and then cooled and coated with diffusing material. Placed inside the bulb is a very thin and fragile, coiled tungsten filament (.0017 inches thick). For the bulb to produce light an electric current is passed through a conductor and the tungsten is heated to the point at which it gives off light. Unfortunately, these bulbs, like many of their relatives, are not very energy efficient; roughly 10% of the energy is used to make visible light. 

How do LED lights work?
The structure of the LED light is completely different than that of the light bulb. Amazingly, the LED has a simple and strong structure. The beauty of the structure is that it is designed to be versatile, allowing for assembly into many different shapes. The light-emitting semiconductor material is what determines the LED's color. 

As indicated by its name, the LED is a diode that emits light. A diode is a device that allows current to flow in only one direction. Almost any two conductive materials will form a diode when placed in contact with each other. When electricity is passed through the diode the atoms in one material (within the semiconductor chip) are excited to a higher energy level. The atoms in that first material have too much energy and need to release that energy.

The energy is then released as the atoms shed electrons to the other material within the chip. During this energy release light is created. The color of the light from the LED is a function of the ingredients (materials) and recipes (processes) that make up the chip.

What are the advantages of LED lights?
LED lights have a variety of advantages over other light sources:

• High-levels of brightness and intensity
• High-efficiency
• Low-voltage and current requirements
• Low radiated heat
• High reliability (resistant to shock and vibration)
• No UV Rays
• Long source life
• Can be easily controlled and programmed

Why are LED lights becoming so popular?
Over the past decade, LED technology has advanced at light speed. In the past, lack of colors and the low intensity made LEDs useful only as indicator lights. As manufacturing methods and technology improved, the LED quickly found homes in more and more applications. These days, the LED is becoming a preferred light source for much more than simple indicators. In fact, today Philips illuminates the world's largest spherical building (Globen arena), the world's largest observation wheel (Singapore Flyer), and the world's tallest free-standing tower (CN Tower) with LED lights!.

LED light sources are also gaining popularity due to the growing energy conservation movement. According to the U.S. Department Energy, no other lighting technology offers as much potential to save energy and enhance the quality of our building environments.

How is LED lighting different than other light sources, such as incandescent and CFL?

LED lighting differs from incandescent and compact fluorescent lighting in several ways. When designed well, LED lighting can be more efficient, durable, versatile and longer lasting. 

LED lighting products use light emitting diodes to produce light very efficiently. An electrical current passed through semiconductor material illuminates the tiny light sources we call LEDs. The heat produced is absorbed into a heat sink.

Common LED colors include amber, red, green, and blue. There is actually no such thing as a “white” LED. To get white light the kind we use for lighting our homes and offices, different color LEDs are mixed or covered with a phosphor material that converts the color of the light. The phosphor is the yellow material you can see on some LED products. 

Colored LEDs are widely used as signal lights and indicator lights, like the power button on a computer.

LEDs are now being incorporated into bulbs and fixtures for general lighting applications. LEDs are small and provide unique design opportunities. Some LED bulb solutions may look like familiar light bulbs and some may not but can better match the performance of traditional light bulbs. Some LED light fixtures may have LEDs built–in as a permanent light source.

LEDs are “directional” light sources which means they emit light in a specific direction, unlike incandescent and compact fluorescent bulbs which emit light – and heat – in all directions. For this reason, LED lighting is able to use light and energy more efficiently in many applications. However, it also means that sophisticated engineering is needed to produce an LED light bulb that shines light all around like an incandescent A-shape bulb.

LED bulbs that have earned the ENERGY STAR are subject to very specific requirements designed to replicate the experience you are used to with a standard A-type bulb, so they can be used for a wide variety of applications. As the graphic on the right demonstrates, a general purpose LED bulb that does not qualify for the ENERGY STAR may not distribute light in all directions and could prove to be a disappointment if used in a table lamp.

Incandescent bulbs produce light using electricity to heat a metal filament until it becomes “white” hot or is said to incandesce. As a result, incandescent bulbs release 90% of their energy as heat.

In a CFL, an electric current flows between electrodes at each end of a tube containing gases. This reaction produces ultraviolet (UV) light and heat. The UV light is transformed into visible light when it strikes a phosphor coating on the inside of the bulb.

LED Basics
The useful life of LED lighting products is defined differently than that of other light sources, such as incandescent or CFL. This is because LEDs typically do not “burn out” or fail. Instead, they experience lumen depreciation, where the amount of light produced decreases and light color appearance can shift over time. Instead of basing the useful life of an LED product on the time it takes for 50% of a large group of lamps to burn out (as is the case with traditional sources), LED product “lifetime” is set based on a prediction of when the light output decreases 30 percent. 

LEDs and Heat
Because LED lighting systems don’t radiate heat the way an incandescent or halogen light bulb does, the heat produced from the power going into the product must be drawn away from the LEDs. This is usually done with a heat sink, which is a passive device that absorbs the heat produced and dissipates it into the surrounding environment. This keeps LEDs from overheating and burning out. 

Thermal management is probably the single most important factor in the successful performance of an LED product over its lifetime because the higher the temperature at which the LEDs are operated, the more quickly the light will degrade, and the shorter the useful life will be.

LED products use a variety of unique heat sink designs and configurations to manage heat, so they may look very different from each other. Regardless of the heat sink design, all LED products that have earned the ENERGY STAR have been tested to ensure that they properly manage the heat so that the light output is properly maintained through the end of its rated life.

Summary
Today is an exciting time for those working closely with LED lighting systems, which allow completely new uses of light.

Far surpassing the simple enclosure of LEDs on a circuit board, Philips excels in all the critical areas that are vital to high-performing LED lighting systems - from thermal management, binning and optics to high-efficiency LED drivers and advanced power components. We have also developed important proprietary technologies to reduce the cost and complexity of LED lighting control, operation and installation - in turn accelerating market adoption.

Though it's been shown to affect the way people live, work, and feel, light has long been considered an afterthought. Philips strives to change that notion, advancing LED lighting technology to create experiences, inspire new applications, and even mitigate strain on our world's resources.