Tag Archives: Citizen

Million shades of white LED

Nowadays LEDs have great efficacy and lifetime. They produce more and more light with less power. I think that it’s less important to increase efficacy because we have already reached what the market demands. What else we need from the light than a lot of lumens? In this blog post, I’ll compare the differences between white LEDs.

We all know that LEDs are available in different color temperatures. For example, Citizen 6 generation’s LEDs are available from 2700K to 6500K. They are also available in different color rendering indexes. Color rendering index simply means how well a white light source can show, or render, colors compared to sunlight. We know that the color rendering index does not always tell the whole truth (You can read more from this blog post).

Nowadays we need a light source that has good efficacy and color rendering, and it doesn’t hurt if the light source can be customized to use in many different luminaires. We want light source that brings colors vivid and alive. Also, design interiors with relaxing atmosphere.

Let’s look into what else affects the quality of light than the color rendering index and color temperature.

White without greenish tone

IMAGE: Black line in the picture is B.B.L. Red circles indicate below B.B.L. LEDs.

In some projects, we want a light source that makes white look whiter. Some LEDs may turn white into light green. Traditional white LEDs’ color temperature chromaticity is on or very near B.B.L. (Black Body Locus). Citizen also produces below B.B.L. LEDs. Their color temperature is below the B.B.L. line. As you can see in the picture, above the line is greenish colors and below the line is reddish colors. Below B.B.L. LEDs make white look pure white and it also renders red colors better. This way we can create light that doesn’t have a greenish tint.

Below B.B.L. LEDs are very popular in shop lighting and everywhere where brisk atmosphere is needed.

Read more about the color temperature from this blog post.

More attractive display with high color contrast

The general color rendering index (CRI) is defined as an average of the sum of first eight R-values. However, these first eight indexes are rather less saturated colors, while indexes R9-R12 represent highly saturated colors. This means that the same CRI doesn’t mean same color rendering.

The Citizen’s Vivid LEDs make colors seem brighter with better color contrast. The spectrum of light has been designed to have as good as possible saturation. This way Vivid LEDs can render bold colors vividly. With better saturation, you can read easier for example newspaper under the Vivid LEDs.

Below you can see a picture where Vivid LEDs are compared. The higher the bar is, the better the color renders. The comparison is done to halogen bulb (0= halogen bulb performance).

Great use for Vivid LEDs are places where good color rendering and concentration is needed, for example, clothing and cosmetic stores, art galleries, schools, hospitals, and offices.

There are two different Vivid LEDs:

  • Brilliant Vivid – Very high color contrast.
  • Natural Vivid – High color contrast.

Vivid LEDs are meant to be combined. Use Brilliant Vivid as spotlights to bring color and textures up, and Natural Vivid as base light because it has better efficacy but has still very good color rendering and contrast.

Change the color temperature of light

Everyone is now talking about “human-centric” -lighting in the lighting industry. It means that by changing the color temperature you can maximize productivity and improve concentration or create comfortable atmospheric feeling. Citizen’s Tunable White is a great solution for “human-centric” -lighting. Its color temperature can be changed freely from 2700K to 6500K. This means that you can achieve warm light like incandescent lamp and daylight with only one module. In addition to changing the color temperature, you can also dim the brightness.

Early Tunable White products have been big sized modules. Citizen’s Tunable white is as small as the COB. This means that you can make a lot of smaller Tunable White luminaires than before. The small size also gives more even light. The spots between cool and warm dies are practically invisible, which guarantee more smoothly light.

By connecting Tunable White into the right control unit, you can change the color temperature and brightness according to the time of day.

Light that gets warmer by dimming

One of the features of the halogen lamp is that when dimmed its color temperature changes warm-toned. Citizen’s Dim-to-Warm COB-LED does the same thing.

Dim-to-Warm is a COB-LED, so you don’t need any complicated special features from the driver, like two-channeling or programming features. Ordinary triac dimmable driver is enough. Dim-to-Warm COB has preset dimming curve, so when you dim it, its color temperature changes automatically just like halogen.

I hope that this blog post gives you some new thoughts for designing the luminaires. When you use any of the LEDs that I just presented to you above, you’ll get a luminaire that has more to provide than just ordinary light source. This way you can have competitive advantage.

You can download presentation about Citizen LEDs below. If you have anything to ask, please do not hesitate to contact me. My email address is taru.matikainen@light.fi and I’m always happy to help you.

Download Here

Tunable White – Achieve color temperature from 2700K to 6500K with one LED module

Tunable White color changing

The Tunable White is becoming a big trend in residential and office lighting. I introduced one color changing LED product, Dim-to-Warm LED, in the earlier post.  In this post, I will tell you about the Tunable White module. Its color temperature can be changed freely from 2700K to 6500K. This means that you can achieve warm light like incandescent lamp and daylight with only one module. In addition to changing the color temperature, you can also dim the brightness.

Why color changing and Tunable White is a trend? How does it impact humans?  Let me shed light on that.

As we know human mind reacts to brightness and temperature of light. Cool light (e.g., daylight) has a refreshing effect and helps us work at school, office, where ever effective work is needed. Where cool light refreshes, the warm light has a comforting and relaxing effect. Naturally, these lights are presented in daytime during sunrises and sunsets.

 

Tunable white color chart

 

How to use Tunable White?

With Tunable White module, you can create better environments for both working and living. You can maximize productivity and improve concentration. Here are just some examples of the usage, but really there are countless ways to use Tunable White. 

One great use for Tunable White is offices. You need a lot of concentration to work effectively. This can be achieved with decent lighting. With this module, as said before, you can control the cool and warm light and dim the brightness. This gives the opportunity to select the right color temperature for office during the daytime.

In residential usage, Tunable White gives a possibility to simulate circadian rhythm. Connect the Tunable White to a control unit, it can change the color temperature automatically by daytime. This way you can enjoy cold refreshing light by midday and get the comforting feeling of warm light by evening.

Now we know some examples, but what kind of luminaires Tunable White is suitable for? Tunable White module is very small sized. This gives options to use it in the wider range of luminaire types.

Here are some examples:

  • Downlight
  • Spotlight
  • Indirect lighting
  • Table light
  • Decorative light

How does it work?

Citizen Tunable White module is made by using “multi-chip” technology. That means it’s made of tiny LED chips that are combined into the same module. Because of its very small size (LCN-C01A is only 15×15 mm), smaller luminaires can be made than before. The small size also gives more even light. The spots between cool and warm dies are almost invisible, which guarantee more smoothly light.

It is made from cool (6500K) and warm (2700K) diodes. The color temperature changes by controlling the output of the two different colored LEDs. LED’s brightness depends on the current; reducing the current the brightness reduces. These features give the option to dim and change the color temperature of LED.

Color curve of Tunable White module.

The Tunable White module has linear color curve because it has two primaries (6500K and 2700K). Advantages of two primaries are greater efficacy and simplicity. As seen in the diagram above, the linear color curve is located under the Black Body Locus (B.B.L.). That affects the color of the light and brings some colors up. You can get white light without greenish tint. This improves contrast in other colors.

A suitable driver needs to have two channel outputs to control CCT and intensity of the light. So, you need 1-10V, DALI or another two-channel driver to control the Tunable White luminaire.

Our high-quality Moons S Series Intelligent Drivers have great compatibility with the Tunable White module. They also have deep dimming from 100 % even to 0,1 %. You can program correct tuning and dimming curves for your luminaire. With Moon’s drivers, you can get everything out of this LED module.

If you have anything to ask, please don’t hesitate to contact us. For more information please download the presentation and the datasheets link down below.

Download Here

Thank You for Everyone at Elfack 2017

I would like to thank everyone who we met at the Elfack Exhibition in Gothenburg, Sweden.

We had some good conversations with our existing customers as well as new people. This year we tested the color quality of Citizen’s LEDs at our stand. We got many answers through our questionnaire and found out that many visitors were excited about this new way of lighting.

If you took part in the test, you will receive the test results soon. We will also share these results with the public a little later.

We had a chance to show you our new products and the feedback we got from you was very encouraging.  I went through all the products in my last blog post, and if you wish to download more information about them, you are most welcome to do so here.

The products displayed at Elfack include:

  • aLED Engine
  • Citizen Gen 6
  • AC COB
  • Citizen Vivid Series
  • Furukawa Heatpipe
  • Merrytek sensors
  • Letaron & aLED Drivers

Our personnel will contact you as agreed, if they haven’t already. In case you have anything to ask, you can contact us directly.

 

What We Are Presenting in Elfack?

Elfack exhibition will be held in Gothenburg, Sweden from 9th to 12th of May. As it has been with previous exhibitions, we will be releasing new products and presenting the latest technology at our stand.

This year we will introduce and present the following products at our stand F04:70.

aLED Engine

aLED Engine

aLED Light Engine

We designed aLED Engine for applications that require a lot of light. aLED Engine consists of Furukawa heat pipe and Citizen COB LED.

In addition you can also choose a suitable optics and LED driver for the light engine from our selection. Suitable drivers are available as on/off, 1-10V dimming and DALI dimming.

aLED Engine is also compatible with Merrytek sensors, which allow you to control the lighting as you wish.

The 300W engine produces 36.000 lm at 4.000K and weighs only 3,6 kg with a driver installed.

aLED Engine will be at our stand in Elfack. There you can see the engine in action and try it with a daylight sensor.

Download More Information

Furukawa HYC Series

Furukawa HYC Series uses heat pipe technology to transfer the heat and makes heat sinks more efficient in cooling the LED.

how heat pipe works

How Heat Pipe Works

Heat Pipe’s thermal conductivity is almost 200 times better compared to copper. This allows the heat sink to be a lot smaller than we are used to.

Smaller heat sink reduces the weight of the luminaire dramatically.

The heat pipes effectively transfer heat from the heat source throughout the whole heat sink cooling the heat source faster than ever.

Heat Pipe vs. No Heat Pipe

Heat Pipe vs. No Heat Pipe

Furukawa heat pipes are compatible with Citizen COBs.

Furukawa heat pipes will be at our stand so you can see and try how light they are.

Read more about Furukawa heatpipe from here.

aLED & Letaron Drivers

aLED Driver

aLED Driver

aLED and Letaron offer a versatile range of both constant current and constant voltage drivers from low to high power (from 1 W up to 600 W).

Ouw own aLED drivers are best suited for high power applications. They are all available in IP68 and can be ordered as on/off, 1-10V dimming or DALI dimming.

Letaron drivers are best suited for low power applications, although they are available up to 52W.

Letaron offers a variety of designs to suit your needs including round, rectangular and slim models.

The Letaron low power drivers are also compatible with OLED light sources.

aLED and Letaron drivers will be on at our stand so you can see and try them yourself.

Merrytek

Merrytek sensors

Merrytek offers a wide range of different sensors. Some sensors come with LED driver and some are independent and can be connected to LED driver.

Merreytek has products particularly designed for eg. homes, schools, stairways, warehouses, offices, parking garages and outdoor use.

Merrytek’s intelligent lighting control products include:

  • Microwave motion and daylight sensors
  • Dimmable LED drivers
  • LED drivers with intergrated sensors

There will be Merrytek products on display at our stand. We will have an aLED engine wiht Merrytek’s daylight sensor on our stand, so you can see how it functions.

Citizen Gen 6, AC COB &Vivid Series

Citizen released Gen 6 COB and AC COB earlier this year with improvements compared to the previous versions.

Thermal Resistance

Thanks to better heat resistance, you can use much smaller heat sink. Gen 4 on the left, Gen 5 on the middle and Gen 6 on the right.

For the new Vivid series we’ve prepared a demo wall at Elfack for you to examine the possibilities of color quality control in LED lighting.

Seminar about color quality

We will organize a seminar about color quality on the first day of the exhibition.

Color comparison Vivid COBColor Comparison Regular COB 3000K Ra80 vs. Vivid Brilliant

The seminar will take place on Tuesday 9th of May.
Time: 16:00-19:00
Place: Hotel Gothia Towers, Tower 1, meeting room R22-23

The program:

  • Doors open at 16:00
  • Coffee
  • Welcome / Arrant Light Oy by Janne Mäkinen, Managing Director / Arrant-Light Oy
  • Color Quality with CITIZEN by Kosuke Tsuchiya, Field Application Engineer / Citizen Electronics Co.
  • Demonstration and open discussion
  • Refreshments and snacks
  • Close at 19:00

Please sign up for the seminar as soon as possible or latest by April 30th. We have limited seats and there is room for the first 20 persons only.

Sign Up for Our Seminar

Welcome to visit our stand F04.70 at Elfack.

All datasheets and other material will be available from our website soon. If you wish to download material about these new products before the exhibition. You can do that here.

How to use Citizen LED simulator

Datasheets are essential part when you compare how different light sources work in your solution. Usually it can be time taking and exhausting to glance at datasheet and find values you are looking for. This gets even harder if you have multiple LEDs or different LED packages, which would mean that you have look at multiple datasheets to get different values.

This is the reason why Citizen has created a Citizen LED simulator. The simulator is very easy to use and makes comparing different LED packages a lot easier. If you haven’t yet tried it or you don’t have the simulator, you can download it for free from our website.

Citizen LED simulator basic view

Citizen LED simulator basic view.

The steps

Follow these steps to use the simulator.

You can choose desired CCT and Ra and selection simulator shows packages and product codes of existing products.

You can choose desired CCT and Ra and selection simulator shows packages and product codes of existing products.

  1. Select the CCT and Ra

First you need to select desired CCT and Ra from condition input field.

You can choose desired CCT and Ra and the selection simulator shows packages and product codes of existing products.

  1. Choose whether you want to search based on the desired lumen amount or driving current

After you have selected color temperature and CRI value, you can choose between driving current (forward current in simulator) or desired luminous flux.

  1. Input the Tc-temperature

Then you can input Tc-temperature. If you have no idea how much Tc is or would be in your solution, values around 60 degrees are realistic to use as many light sources reach temperatures close to that while being used.

Example

In this example, I have chosen that I want my LED to be 4000K, Ra80 Min. And I want to see what options we have to get around 3000 lumens out from luminaire. Luminaire optics etc. will drain around 300-400 lumens in my solution. So I have determined that I need 3400 warm lumens from LED and estimated that Tc-temperature is 60 degrees.

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I can see that I have ten different LED packages I can get the 3400 lumens from. In first column after product code you can see what current you should use to get these values. If you don’t have LED driver, in which you can choose output current, it is recommended to then select current value you have LED drivers available in. In this case, 700mA seems to be a good choice as many of the LED’s have driving current close to that.

So I change “forward current” instead of “luminous flux” from the condition input and insert 700mA.

LED packages which give you desired lumens with 700mA. We still have six options to choose from.

LED packages which give you desired lumens with 700mA. We still have six options to choose from.

This will give me a list of LEDs I can use with 700mA driver. And more importantly give me a good overview of LED packages that can give me my desired lumen amount. If you have problem that you can’t find driver with suitable current, you can contact me for help.

In this case, CLU028-1204 would suit my lumen need quite nicely and CLU048-1212, would probably be an overkill for this application. All the other options, might suit my solution although they give roughly 10% more lumens. Whether this is ok, depends really on my application and desired efficacy.

Other applications

Citizen LED simulator is also powerful tool to use when you want to see easily how much lumens you get when driving LED with different currents. Good example is that if you have LED driver which has different current options and flexible LED package, you can use only two components to realize many different lumen packages.

As an example I did this exercise with ELT 42W multicurrent LED-driver and Citizen CLU038-1205 LED package. This driver has option to select different driving currents with dipswitch. If we take Esko’s advice and look from driver datasheet, we can see that output voltage area is suitable from 500mA to 1000 mA.

Below you can see LED characteristics with different current. I have also added forward current column to make this table easier to read. Tc temperature is 60 degrees in all cases.

Table with CLU038-1205 4000K Ra80 LED from 500mA to 1000mA.

Table with CLU038-1205 4000K Ra80 LED from 500mA to 1000mA.

You can also use the LED simulator to estimate the amount of lumens lost due to your luminaire (optics etc.). If you measure LED Tc-point and input the driving current you use to simulator, you should have pretty good estimation that how much lumens you should get out from your luminaire.

If you find out that the loss is too big, the you can either change the LED to a different package or improve the optics of your luminaire.As you can see, you can use this driver & LED combo for a luminaire from ~2500lm to ~5000lm.

Please feel free to contact me if you have any questions.

You can download the latest simulator below.

Download COB Selection Simulator

 

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.

What is COB LED

COB LEDs are very popular nowadays in LED lighting business. We talk and write about COBs, and our customers use COBs in their luminaires, but what exactly is COB? First of all, the abbreviation COB comes from words Chip-on-Board.

Citizen COB frontside, The yellow substance is phosphor, which turns the blue light of the chip white

Citizen Electronics’ COB frontside, The yellow substance is phosphor, which turns the blue light of the chip white

In COB packages many LED chips are usually attached to substrate with non-conductive adhesive. LED chips are wire bonded together to make different LED setups. The amount of single LED chips, inside a one COB LED package, can vary from few pieces up to several hundred pieces. Substrate is located on base material. Base material of COB LED is usually MCPCB or ceramic PCB. COBs often have blue diodes and use yellow phosphor layer to convert light to desired color temperature.

 

General drawing of a COB LED.

General drawing of a COB LED.

In early years of 21st century there were few SMD LED packages, which could be considered almost as COB packages due to their construction. Generally COB LEDs became available and popular in LED lighting market around year 2007. At first there were first quite a lot doubts towards COB LEDs in the market . Mainly because this package construction enabled LED manufacturers to put high powers in small package. Over then, this “high power” meant over 10W,

Also there was very little experience of COB LEDs, so these LEDs had a lot to prove.  Although now several lifetime tests have shown that COB packages are very reliable, if heat management is done properly.

When thinking about heat management, one important feature is thermal resistance. But it is worth noticing, that you can’t define which COB LED is better to conduct heat just from thermal resistance value. You should actually test LEDs in your own application.

Today COB LEDs are available from few hundred lumens up to 30,000 lumens. This means that

Citizen COB backside, aluminium PCB, which will conduct the heat to the heat sink effectivily. However it won't be enough to cool the LED

Citizen Electronics’ COB backside, aluminium PCB, which will conduct the heat to the heat sink effectively. However it won’t be enough to cool the LED

almost every light source can be replaced with COB LED. So available powers go from few watts up to almost 200 watts. The most powerful COBs require exessive heat sinks because they generate a lot of heat.

COBs offer great variety due to possibility to have many different LED setups even inside one COB package. Usually LED manufacturers have different lumens packages available in same size COB, so lighting manufacturers is able to use e.g. same connectors and optics in different solutions. Also it is good to remember that usually you can underdrive or overdrive COB LEDs and those might have quite wide driving range. This allows you to drive LEDs with very high efficacy, you can make balanced solution or you can make economical lumens.

COB LEDs are generally used in luminaires where lamp or single spot light sources have been used. So basically COB LEDs are used in almost every kind of luminaire. Although COB LEDs are used less often in linear lights or  panel lights, some solutions of that kind have been made with COBs. Luminaires which have really high luminous flux are usually made with more than one COB LED to distribute heat flux and to ease design of heat sink.

Sochi Olympic cauldron, Lights made using Citizen COB

Sochi Olympic cauldron, Lights made using Citizen Electronics’ COB (Copyright: Zers Pride LLC)

COBs offer very high luminous fluxes from small size packages and thus allow flexible design of luminaire. This gives you more freedom, when designing a luminaire. COB packages usually have excellent uniformity of light from light emitting surface, this is important e.g. if you want to avoid multiple shadow effect, which might occur with SMD based solution. It is also very easy to test COB LEDs. You only need COB LED, constant current driver and e.g. piece of aluminium, which can be used as heat sink.

LED Shadows: On the left, a shadow from a COB. On the right, a shadow from a LED with multiple light sources

LED Shadows: On the left, a shadow from a COB. On the right, a shadow from a LED with multiple light sources

We can see that COB LEDs have been very important development step in LED lighting business. This great package design has allowed to increase powers used inside one LED package tremendously. Also one good indicator of success of COBs is that today every major LED manufacturer and package maker has COB LEDs in their selection.

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