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What is OLED in Lighting?

OLED means Organic Light Emitting Diode.  It works in similar way than (semiconductor) LED. Both need positive and negative charge carriers to generate electrical current and finally generate light.

It is a surface light source based on organic material layers. LED, on the other hand, is a point light source that is based on semiconductor materials. But the operation is based on the same principle.

OLED as Surface Light

OLED as Surface Light

The large-area LED modules, that are covered by opal diffuser, are basically similar light sources as OLED panels. Without this diffuser, these LED modules also are point light sources because of small SMD LED diodes they have on their surface.

OLED panels are surface light sources by nature. They give uniform light.

The benefits OLED:

  • Its light has spectral power distribution very close to sunlight.
  • Color rendering index (CRI) of 90.
  • Produces no glare
  • Produces very little heat(<35°C),
  • Doesn’t produce any UV and therefore it doesn’t cause blue light hazard risk.
  • Panels are thin and lightweight.
  • Simple light: panels don’t need many accessories unlike LED, such as heat sinks, diffusers, or other optics. It only needs the power source and the light source itself.

    Spectrum of OLED

    Spectrum of OLED

Structure of OLED

The OLED structure consists of layers. These layers have different purposes.

There are basically THREE different kinds of layers that have some purpose. Of course, you need anode and cathode terminals to bring electricity from outside world to the panel. As an example, LG Display uses Aluminium as cathode material and ITO (indium tin oxide) as their anode material.

  • Light generation layer: Emissive Layer (EML). Generates light.
  • Electrical current flow guidance: Electron Transport Layer (ETL), Hole Transport Layer (HTL) and Hole Injection Layer (HIL). These layers are used to transport charge carriers in optimal way to the light generation layer, EML. But also, they have to be optically suitable for light generated in the EML layer so that as much light as possible is extracted from the panel.
  • Third type of layer: Encapsulation. The encapsulation layer is used to protect inner optically active layers from any outside harm that could deteriorate the operation of the panel.

This kind of set of layers is called a stack.On top of the stack is the encapsulation layer.

OLED Structure

OLED Structure

For example, LG Display uses two-stack structure for 3000K and 4000K OLED panels and three-stack structure for 2700K panels. Because there are more stacks in 2700K version, the overall voltage over the panel is a bit higher.

Encapsulation

One major problem with the organic materials is that they are very sensitive to oxygen and moisture. This means that OLED panels need to be protected – as even a single water or oxygen molecule can harm the panel.

The encapsulation layer also protects from minor physical impacts. If this encapsulation layer deteriorates it will affect the optical layers. Usually strong glass is used for rigid OLED panels. But flexible panel is gaining more and more popularity. Flexible panels use plastic.

 

Drawbacks

The major drawbacks of OLED panels are:

  1. Easy to break

At the moment, most panels use glass substrates. These substrates are very fragile and are easy to break when not handled with care. This will improve in future as technology develops and plastic substrates will gradually replace glass.

  1. Cold endurance

You can’t use the panels in temperature of under 0 degrees of Celsius. This will obviously place some constraints for the use.

It is very probable that the cold endurance will get better in the future as the technology develops.

  1. Technological immaturity

OLED is still very young technology and it can’t produce very large amounts of light. It also loses to LED in luminous efficacy.

This will obviously improve in the future as manufacturers are investing in new product facilities.

Applications

As a surface-type lighting element, OLED can be used in different kinds of interior designs. It can give the background or accent/ambient lighting for example some artworks or other objects.

OLED as an Accent Light

OLED as an Accent Light

Basically, new application areas are up to you.

You can find and download ideas about OLED lighting from our website.

 

FAQ: OLED – Panels

From this post, you can find the most frequently asked questions related to OLED panels. The post will be updated in the future if new questions arise.

Q: What is OLED? Does it work in the same way as LED?

A: OLED means Organic Light Emitting Diode. It works in similar way than (semiconductor) LED. Both need positive and negative charge carriers to generate electrical current and finally generate light.

OLED Structure

Structure

You can read about the structure and tehnology of OLED from my other blog post.

Q: How OLED panel is attached on the surface/profile that is used in the luminaire?

A: The panel can be attached in many ways, but most common way  is to use adhesives. The screw connection is not recommended for panels.

Every panel manufacturer should have a list of adhesives that are not allowed with their products.

Q: How the to handle OLED panels?

A: You must handle them with care. At the moment most panels use glass substrates and because the panels are very thin, they break very easily. In the future, plastic substrates will replace the glass substrates. This will obviously decrease the risk of breaking the panel.

You can find more exact instructions on handling the panel from the datasheet of the panel.

Q: Can you bend the OLED panel because it is so thin?

Bendable OLED Panel in Luminaire

Bendable Panel in Luminaire

A: You can’t bend the glass substrate panels.

Plastic panels are ok to bend. There is a limited bending radius that can be found from the datasheet. Within that limit, you can bend the plastic panels almost endlessly.

Q: How you connect the OLED panels if you want to light many panels at time?

A: You can drive many panels by connecting them electrically in series. So you have the same current going through each panel and you get the same luminous output for each panel if they are the same products. Thus you can drive for example 4-panel luminaire with one driver as long as the voltage range of the driver allows you to do so.

Q: Which temperature range is allowed for OLED panels?

A: Basically, OLED lighting can be used only in indoor lighting at the moment. For example, LG Display informs in the datasheets of their panels, that operating temperature has to be over zero degrees of Celsius, and this applies also to storage temperature. Only transport temperature can be lower than zero degrees of Celsius, but only for a limited time.

Typical recommended operating temperature range is 0..40°C.

Q: What kind of new application can be done with OLED?

A: One interesting application is so-called transparent connection. In this case the panel is attached inside a glass plate. The current/power is then provided to the panel through metal mesh transparent conductive film.

OLED Transparent Connection

Transparent Connection

You can find and download ideas about OLED lighting from our website.

How to select modules + driver package

In this blog post we concentrate on how to design a LED lighting package as a whole. And what different aspects you will have to take into account when selecting a light source and a driver.
I decided to write this as a case example so that the post is more concrete.

Most of the luminaire projects starts with the need for certain amount of lumen needed out from the luminaire. Then there can also be requirements for the shape and size for the light source. Color temperature, color rendering and lifetime expectancy might also be critical, but those are topics for a blog posts of their own.

LED Modules

LED Module

Case example

So in this case you have specified that the luminaire needs to achieve:

  • Lumen output 2000lm
  • Color Temperature 4000K
  • Ra(min)80
  • Lifetime 50 000 hours (LM70 for the whole luminaire)
  • Efficacy >120lm/W
  • Linear light source. Max length of 120cm

With these specifications, the finding of the suitable solution shouldn’t be a problem.
There are, however few things that have to be taken into account when looking at the data of LED modules:

  1. Lumen output: Some of the lumens from the light source will be lost due to the optics. The amount of lost lumens is around 10%. Therefore, you should look for light sources that can give you at least 10% more lumens than you need.
  2. The shape of the light source. Do you have a minimum size for the light emitting surface? The luminaire in this example can be built with modules around 30cm in length, but that would probably not be perfect fit your luminaire. It would leave a lot of empty space and the light distribution wouldn’t be even.

With those two in mind, you would need a light source that gives you roughly 2200lm and fills the whole 120cm evenly. That could be reached with for example 4 modules with lumen output of 550lm and length of 30cm or with two modules with 1000lm output and length of 60cm.

Selection of LED Drivers

Selection of LED Drivers

The Driver

For the case study presented above, you still have one more step to go: choosing a LED driver. Esko already wrote a good guide on this, so I’m going to be brief.

Before we can start, you have to specify one thing: How many LED modules do you want to drive with one LED driver? Only one module or several modules in series?

In this example you would probably want to drive all the modules with just one driver. This might be the case with all luminaires. In more complex lighting systems you might use several drivers. To find a suitable driver you will need to:

  1. Check the current that you want to drive your light source(or sources) with.
  2. Check the voltage of your light source (or sources) and check that it fits the driver’s voltage range.

You should always leave some room for the voltage as there might be some variations in the diodes. Check that the driver has around 10% lower minimum voltage and 10% higher maximum voltage than your light source.

So there you have it in brief. If you need more help or would like to leave a comment, please leave a comment or contact me!

You can also use our free tool to build your luminaire.

How to Choose a Suitable Constant Voltage LED Driver for Your Application

We discussed earlier about general characteristics of LED drivers and how to choose a suitable constant current LED driver for your application.  Now, I’m going to tell you how to choose a right LED driver for your constant voltage application.  As told in the previous posts, LED drivers are divided into two different categories: constant current and constant voltage drivers. But that is not the only thing you have to take into account when selecting the driver. In this post, we are focusing in constant voltage drivers.

Constant voltage drivers are generally used when you need a stabile voltage fed to your LED. You can check the datasheet of your light source whether it needs constant current or constant voltage. If it says for example 12V or 24 V, then it needs constant voltage. And for example 350 mA or 700mA means that you need a constant current driver. Constant voltage driver (power supply) keeps voltage constant (e.g. as 12 V DC), but feeding current varies according to the load (the higher the load the bigger the current)

Datasheet of Constant Current and Constant Voltage LED Module. The circled value tells you does the module need constant current or constant voltage.

Datasheet of Constant Current and Constant Voltage LED Module. The circled value tells you does the module need constant current or constant voltage.

With these easy step-by-step instructions, you will find a suitable driver for your luminaire or signage application.

Step one: What voltage does your LED application need?

As already mentioned, you should find the voltage that your LED needs, from the datasheet or from the product itself.  For example if your LED needs a voltage of 12 V, you should find a driver with 12 V DC output voltage. If LED demands 24V, you should find a driver with 24 V DC output voltage. So that is pretty straightforward.

Step two: How powerful driver do you need?

The power consumption of the LED application can also be found from the datasheet or from the value label in the product.

Remember that if using multiple LED components, you have to find a driver that can feed all the LED components in your luminaire (in parallel connection).

 

GE Lightech 12W, 12V LED driver

GE Lightech 12W, 12V LED driver

Step three: What current range you need from the driver?

Again take a look at the datasheet and check the current of the LED application. If you have multiple LEDs, you should add the current together. Then you should find a driver with a current range that your LEDs fit into.  On the other hand if you have checked well the power you need then your driver will give enough current to get your LED application burn on the right level.

And in some constant voltage LED applications the current is not mentioned at all, only the voltage and the power. Then you can skip this part.

Step four: Do you need dimming? And what type of dimming?

A need for dimming is mainly dependent of the specification of your LED application. If you don’t need dimming, a normal on/off driver is enough for you. If you need dimming, there are many different types of dimming, but that is a topic for another post.  But e.g. in signage applications dimming is not normally required.

Step five: What are the physical dimensions the driver has to fit into?

You should also consider if there are some limitations for the physical dimensions of the driver. These will obviously have an impact on your driver selection. You will generally find the physical dimensions of the driver from its datasheet.

Step six: is the driver placed inside the LED application or outside (built in or independent version)?

If the driver is placed outside the LED application without any fixing the driver should be classified as an independent version. This means that the input and output cables of LED driver have strain reliefs to secure safe cable connections in case of any pulling force.

Step seven: What kind of environment the LED application is used in?

Where is your LED application designed to be used in? If it is designed for indoor use, then you probably won’t need to think about IP-classification so much. Of course if the luminaire is used in a room with a lot of dust or moisture, this has to be taken into account.

And for outdoor use check that the product is approved for min IP67 area.

GE Lightech 200 W 12V, IP67 driver

GE Lightech 200 W 12V, IP67 driver

IP20 class drivers it means that this driver can be used in indoor lighting applications but hardly stands harsh conditions in outdoor lighting unless the luminaire itself is waterproof thus protecting the driver.

But when designing a luminaire to outdoor use, then you should check that that the driver has good enough IP-class.

Usually IP67 drivers are heavier in weight, driver electronics is molded in many cases with plastic (e.g. potted) and the electrical throughputs of the wires both on primary voltage and the secondary voltage side are sealed with required protection against moisture.

Step eight: Approvals, is the driver suited for European or American standards?

Does the driver have any approvals? And are the approvals for Europe (ENEC), America (UL) or for another area? This can generally be found from the datasheet of the driver. In most cases it is the benefit of both the customer and supplier that drivers are certified for that area where they are used.

ROAL Strato CV 24V with ENEC and UL approvals

ROAL Strato CV 24V with ENEC and UL approvals

So there you have it. With these steps you should be able to find a suitable LED driver for your application. If you don’t, please leave a comment or contact me directly.

Letter For Customers and Partners

Janne Mäkinen, Managing Director, Arrant-Light

Janne Mäkinen

I am very pleased to be writing this letter to our customers and partners – and to thank all of you who have trusted us over these past 30 years, helping us to sustain and grow the company.

The history of Arrant-Light Oy dates back 30 years to when my father, Tarmo Mäkinen, founded the company in 1984. The company initially focused on long-life fluorescent lamps and light bulbs, and very early on began offering a group replacement service for large companies. In the 1990s, the company expanded into supplying lighting components to luminaire manufacturers. Today, Arrant-Light Oy is a specialised supplier of lighting components, with LED components and related drivers, optics and accessories forming the largest product group. From the very beginning, the company has been driven by a principle of delivering best-in-class products that are easy to use and have a long service life.

Arrant-Light Oy currently delivers over 20,000 components a day to 11 countries and is the market leader in white LEDs in Scandinavia and the Baltic countries, with a more than 40% share of the market. Most of our customers benefit from a 24h delivery of stocked items.

With 30 years of experience under our belt, we are well placed to bring our customers the latest products with the highest efficacy. We engage in continuous research and development with our current suppliers and partners, and we will also be announcing the addition of new suppliers and interesting brands later this year.

To celebrate our 30 years in business, we decided to redesign our company logo. The new logo

Logo for the new aLED brand

Logo for the new aLED brand

will be followed by the introduction of aLED, the new brand name for Arrant-Light Oy’s own LED modules and other components. The aLED brand will also include a number of carefully selected products from our partners. aLED is a guarantee of quality and reliable delivery at a competitive price.
Our website at www.light.fi has also been given a makeover. The site is now even easier to navigate, and our aim is to increase the amount of easily available information on the site to make it a useful resource for professionals. Why not take a look at the new website!

I would again like to thank everyone for the past 30 years. I am confident that we can continue to provide You with the best service and products in the market. Development is an ongoing process.

Best wishes for autumn days filled with light,

Janne Mäkinen
janne.makinen@light.fi
Managing Director
Arrant-Light Oy

 

Citizen COB LEDs generation 3 – What has changed from the last generation?

Citizen has released brand new generation 3 COB LEDs. Is this post I go through briefly what changes and advantages this update brings to Citizen LEDs.

First thing which is noticeable with new LEDs is that product code changes from e.g. CLL022 to CLU024. Third letter has been changed to ‘U’ to inform that generation 3 COBs are UL recognized components.

Most powerful of the generation 3: CLU054

Most powerful of the generation 3: CLU054

Citizen has managed to improve LED performance significantly in generation 3 products compared to the last generation. One of the main updates has been done to package performance, which has allowed better light extraction from generation 3 LED package. Other main update has been in LED die inside package. These new LED dies do not allow only better performance, but also give you the possibility to have even wider current range used with LED. In practice this means 50% wider overdriving range compared to generation 2 LEDs.

What is the best about these generation 3 packages besides great performance improvement is that outlines and mechanical dimensions remain the same. So you can easily update these new products to your existing luminaire designed for previous Citizen LEDs. This also means that all the accessories designed for previous versions still work with new LEDs.

When you are considering update from generation 2 to generation 3, please keep in mind that most probably you will find four suitable options from generation 3 LEDs to replace your existing LED. Generation 3 will give you much more freedom to choose from significant improvement in efficacy, getting balanced performance update or getting economical lumens with same efficacy. If you need help in the selection, I will be happy to help you.

Smallest of the new generation 3: CLU024

Smallest of the new generation 3: CLU024

Citizen has also increased minimum color rendering index for generation 3 from Ra65(min) to Ra70(min). These Ra70 products allow very high lumen output with excellent luminous efficacy. This also allows wider usage of high efficacy LEDs in places where Ra70 is minimum requirement.

If you have some questions or comments about Citizen LEDs, please contact me directly or comment below.

How to Construct a LED Luminaire  

There are many aspects that have to be taken into account when constructing a LED luminaire. In this post I will give you some tips how to build a LED luminaire and which things have to be considered.

There are five steps for designing LED luminaires:

  1. The definition of lighting requirements; how much you need light in certain environment/space.
  2. Defining some design constraints and special requirements, for example related to optics or withstanding high temperatures.
  3. Optical, thermal or electrical design.
  4. The number of LED components is then calculated based on the lumen quantity defined in the specification.
  5. Finally, all components to construct the final luminaire, or prototype in the first stage, have to be defined and specified.

In this post, we concentrate on this last step, how to construct LED luminaires from lighting components rather than the step-by-step luminaire design process itself.

When you start the construction of a luminaire from lighting components, the first thing that you should decide is which kind of LED you use in your luminaire. Basically there are three different options:

  • High-power COB LEDs
  • Mid-power LEDs
  • Low-power SMD LED diodes.

In this post, I’ve divided the options to two different groups: high-power COB LEDs and mid- and low-power LEDs, which usually are SMD LED components.

High-power LEDs

COB Luminaire

Luminaire using Citizen COB LED

High-power LED option comes usually into question when there is a need for large luminous output. Citizen Electronics’ COBs are powered from 3W COB to 80W COB with typical power consumption values. The luminous flux ranges from about 100 lumens to 13 000 lumens with typical current and even to nearly 20 000 lumens with maximum operating conditions. When constructing a luminaire using COB LEDs there is a need for some kind of heat management because of large power density on small area that has to be conducted away from COB LED. The power density can be even 22 W/cm2 on light emitting area of about 8.5 cm2. Many times price target sets the limit for cooling, and active cooling methods can’t be used. This requires the use of passive heat management. In another words, you need some kind of heat sink. Typical material is some aluminum alloy with a fin-shaped structure in order to increase the overall surface area of the heat sink element. Additionally, some kind of thermal paste or other thermal interface material is inserted between the LED and heat sink in order to increase heat conduction from the LED to the heat sink and ultimately to the luminaire body.

Of course you need also LED driver to feed electric current to the COB. When talked about COB LEDs, many times you can drive only one or two LEDs with the same driver. Esko Väisänen explained the selection process of LED driver in his post: How to choose the right LED driver.

In addition to the COB LED and the LED driver, you may also need some optics, such as lens or reflector to increase light quality coming out of your luminaire. Current feeding to your COB LED can be realized either by soldering wires to the COB or using special sockets or connectors to supply power to the LED.

Mid-power and low-power LED

LED Module, which can be used in luminaire needing good light distribution.

LED Module, which can be used in luminaire needing good light distribution.

When constructing a luminaire using mid-power or small-power LEDs, heat management is not such a big problem as in the case of high-power LEDs. Normally the key target for luminaires using mid- or small-power LEDs is the light distribution or color consistency. Applications range from store lighting through emergency lights to decorative lighting, even to LED bulbs. Diffuser plates, for example opal diffuser or prismatic diffuser, can be used in these kinds of luminaires. The luminaire in which small- or mid-power LEDs are used include usually PCBs. The alternatives are usually FR-4 or aluminum metal-core PCB (MCPCB) on which SMD LED diodes are assembled. Usually, if the total power consumption of the LED module exceeds 10W, the aluminum MCPCB is used in order to better conduct heat away from the PCB. Depending on the case, some kind of extra aluminum profile can be used to conduct heat away. If the luminaire has a closed structure, you should also take care of the heat inside the closed luminaire. Heat should be distributed and conducted away from the LED so that the LED does not get too hot. FR-4 can be used for lower power modules by using enough copper pour to spread heat uniformly. FR-4 boards are also cheaper than aluminum PCBs and are used if price becomes the key issue and power consumption is not the problem. In addition to the PCB and the LED diodes some kind of connectors are necessary to connect the LEDs into the outer world electrically.

Also these luminaires need a LED driver to give current to LED components. In addition to heat formed inside the LED components themselves, heat forms also in the LED driver operation. This causes problems if the luminaire structure is closed as discussed earlier. If you use many modules within one luminaire, you will need some kind of cabling between the modules. When designing for example a linear luminaire, there may be a need for some cabling throughput. This will usually mean that cabling has to go on the other side through some plastic or metallic profile. Some additional screw holes may be possibly needed for attaching the metallic profile into the luminaire body.

If you have any questions or comments, please feel free to leave them on the comments field.

How to choose suitable Constant Current LED driver for your application

Selection of LED Drivers

Selection of LED Drivers

We discussed earlier about the general characteristics of LED drivers. In this post, I’m going to tell you how to choose a right LED driver for your application. LED drivers are divided into two different categories: constant current and constant voltage drivers. But that is not the only thing you have to take into account when selecting the driver. In this post, we are focusing only in constant current drivers.

Constant current drivers are generally used when you need stabile current fed to your LED. With constant current driver, it is easier to manage the right brightness. You can check the datasheet of your light source whether it needs constant current or constant voltage. If it says for example 350mA, then it needs constant current. 12V or 24V means that you need a constant voltage driver.

In this post, we’ll take a look at constant current drivers.

How to choose a constant current driver for your application?

With these step by step instructions, you will find a suitable driver for your luminaire.

Step one: What forward current does your LED need?

As already mentioned, you should find the forward current your LED needs, from the datasheet. For example if your LED needs a current of 350mA, you should try to find a driver with 350mA output current.

Step two: How powerful driver do you need

The power consumption of the LED can also be found from the datasheet or at least it can be calculated with the data in the datasheet. The power consumption can be calculated by multiplying typical driving current value by typical forward voltage value that both can be found in the LED data sheet. Sometimes you can even find the power consumption directly from the datasheet.

Remember that if using multiple LED components, you have to find a driver that can feed all the LED components in your luminaire.

ELT 10W, 500mA LED driver

ELT 10W, 500mA LED driver

Step three: What output voltage range you need from the driver
Again take a look at the datasheet and check the voltage of the LED. If you have multiple LEDs, you should add the voltages together. Then you should find a driver with a voltage range that your LEDs fit into.

Step four: Do you need dimming? And what type of dimming?

A need for dimming is mainly dependent of the specification of your luminaire. If you don’t need dimming, a normal on/off driver is enough for you. If you need dimming, there are many different types of dimming, but that is a topic for another post.

Step five: What are the physical dimensions the driver has to fit into?

You should also consider if there are some limitations for the physical dimensions of the driver. These will obviously have an impact on your driver selection. You will generally find the physical dimensions of the driver from its datasheet.

Step six: What kind of environment the luminaire is used in?

Where is your luminaire designed to be used in? If it is designed to indoor use, then you probably won’t need to think about IP-classification so much. Of course if the luminaire is used in a room with a lot of dust or moisture, this has to be taken into account.

ELT 60W, 700mA, IP20 driver

ELT 60W, 700mA, IP20 driver

IP20 class drivers it means that this driver can be used in indoor lighting applications but hardly stands harsh conditions in outdoor lighting unless the luminaire itself is waterproof thus protecting the driver.

But when designing a luminaire to outdoor use, then you should check that that the driver has good enough IP-class.

Usually IP67 drivers are heavier in weight, driver electronics is molded with plastic (e.g. potted) and the electrical throughputs of the wires both on primary voltage and the secondary voltage side are sealed with required protection against moisture.

ELT 10W, 350mA, IP67 driver

ELT 10W, 350mA, IP67 driver

Step seven: Approvals, is the driver suited for European or American standards?

Does the driver have any approvals? And are the approvals for Europe (ENEC) or America (UL). This can generally be found from the datasheet of the driver.

So there you have it. With these steps you should be able to find a suitable LED driver for your application. If you don’t, please leave a comment or contact me directly.

You can also use our Light Builder to select a driver.

How to choose the right LED?

 

There are tons of different LEDs even in one manufacturer’s selection so how on earth can you find the right LED for your solution?

In my previous post I discussed about the basic characteristics and operation principles of LEDs. In this post I will discuss about different packages and about the facts that will probably have an impact on your selection.

I will divide LED light sources into three categories:

  • SMD LEDs
  • COB LEDs
  • LED Modules

I will now look more closely on these three categories before we jump into the actual selection.

SMD LEDs

SMD LED

Citizen CLL600 – Example of SMD LED

SMD LEDs are small diodes used in LED modules. They have to be assembled on printed circuit board (PCB). Generally they allow you to design any kind of luminaire and allow you to make uniform light source. On the downside, SMD LEDs always require them to be assembled on a PCB.

 

 

COB LEDs

COB LED

Citizen CLL052 – Example of COB LED

COB = chip-on-board. COB is a small package that combines many diodes as a one light source.  COBs have generally small dimensions and produce a lot of lumens. You can attach COB directly to the heat sink, which allows excellent heat management.  COBs don’t need a lot room in the luminaire fittings and are therefore well suited for luminaires with small room for light source.

LED Modules

LED-modules

Example of LED modules – Linear and rounded

LED Modules are made of SMD LEDs and PCB. LED distributors offer standard modules which in general are made for the common need. For example we have different sizes of linear modules as well as rounded modules. These modules have a certain lumen package which remains the same from LED generation to another. This enables lighting manufacturer to update their luminaires with more efficient LEDs. If you can’t find a suitable LED module for your application, you can always contact a manufacturer and ask them to design a custom module for you.

 

How to know where to start

The main thing that has an impact on your LED selection is, obviously, the type of luminaire you are manufacturing.  If you are transforming an old luminaire into an LED luminaire, then you will probably have some demands on the physical dimensions of LED.

For example, if you have a T5 or T8 fluorescent lamp, you will need a light source that

a) gives you linear light
b) gives you uniform light
c) fits in to the old luminaire’s body

If you are not restricted by physical dimensions, then you have a lot more options.  For example if you are building a whole new luminaire, the physical dimensions are not so critical. Or at least you get to decide what are the physical dimensions the LED needs to fit into.

COB Luminaire

Luminaire using Citizen COB LED

The other important criteria for LEDs is the amount of lumens you need. You might have an older luminaire that you need to replace, so ideally you would want as much light as the old one produces. So for example, if you have a 120cm fluorescent lamp and it produces 2700 lumen you will want a light source that:

a) fits into the 120 cm long body
b) gives you uniform and linear light
c) gives you  enough light (you won’t necessarily need 2000lm if you have better optical efficiency)

So in this example, you could use for example two modules that are less than 600mm in length and produce 1000lm each. Or you could use smaller modules, for example four modules that are less than 300mm in length and produce 500lm each.  As you may have noticed this selection does not give you the same amount of lumens from light source, but you will still get the same amount of lumens out of the luminaire.

Then there are obviously the color rendering index (CRI) and color temperature (CCT), both of which are mainly depending on the application of your luminaire. For example if you are building a luminaire for a clothing store or an art gallery, you will probably want as high color rendering as possible. On the other hand if you are manufacturing a street light, you probably won’t care about CRI so much.

If you need any help with selecting the LED, or if you disagree with any of my views, you can share your thoughts on the comments below.