What is LED lights, Kelvin, Lumens, Ra?

What is LED lights and LED light sources

LED stands for Light Emitting Diodes. They have been known for a long time and used in all kinds of devices as indicators, such as in hi-fi, coffee masks, cars, household appliances, but it is only in recent years that the amount of light emitted from them has become so powerful that they can be used as light sources.

LEDs can illuminate in many different colors, but can be categorized by being able to illuminate only one color at a time. The colors that are easiest to make on LEDs are blue, yellow, green and red. The white color cannot be made with an LED directly. What the light manufacturers do is that they make a blue diode and let the light pass through a phosphor layer, which changes the blue color to white. With the three LED basic colors red, green and blue you can make all colors in the color spectrum. This is used in all color televisions, where all colors are created from these three LED primary colors. Any color is created by mixing the RGB colors at different intensity. Typically, each of these three primary colors has 256 light levels, and so the number of colors becomes 16.8 million (256x256x256).

LED Color Temperature

Color temperature is a measure of the color of the light itself. Color temperatures above 5000K are called cold colors and color temperatures below 3000K are called hot colors. The more of the red color, the warmer the light.

As an example, the old incandescent bulbs go all the way down to 2500K and the halogen bulbs a little higher or around 3000K. LEDs are available in many different colors, ranging from around 2700K, which some manufacturers call VWW (Very Warm White) and then the typical WW (Warm White), which is around 3000K and White, which can be much higher or up to 6000K .

RA (or CRI)

RA value is the property of light to reproduce colors from the material or things on which light falls. The smaller the RA value, the poorer the light for reproducing colors from the material or things on which the light falls.

An old-fashioned incandescent bulb and a halogen bulb have an RA value close to 100, which is the optimal color rendering. A light bulb contains all light colors and can therefore reproduce all colors. In a color television where all colors are made of Red, Green and Blue, all colors can be created, but since these colors are all created by only the three LED primary colors, they cannot reproduce all colors to which the light falls. Therefore, a white light created by these three LED primer colors will typically have a very low RA value or down to around 20.

Lumens

The lm or lumen tells you how much brightness comes from the light source. The greater the number, the greater the brightness. Before the LED era, one might say (perhaps a little popular) that the brightness was more or less expressed in watts.

You went to the store and bought 40 or 60 watts of bulbs, which were the most common sizes. But for other purposes you could get from approx. 10 watts to 200 watts bulbs. Now that we have got LED and high-efficiency halogen light sources it makes no more sense to talk about watts. The new expression of the light source's strength is Lumens. The old 40W bulbs gave about 450 lumens, while 60W bulbs gave about 800 lumens.

LED lifetime

The lifetime of the LED is much longer than the old incandescent bulbs or anything from 10 - 25 times longer. The old incandescent bulbs have a service life of approx. 2000 hours, while LED has a lifetime of approx. 20,000 - 50,000. However, it should be noted here that the lifetime of the LED is calculated so that when the light from the LED has decreased by 50%, it is the lifetime of the LED in question.

The life of the old incandescent bulbs is calculated until the incandescent bulb no longer glows. The lifetime of the LEDs is highly dependent on the cooling that is on the LEDs. All ODSIF's lamps have a large aluminum cooling surface, which ensures that the LEDs can get rid of the heat and therefore have a life of 50,000 hours. What does this mean this year? Well if you now use LED light for 4 hours daily on average, then the LED light lasts for 34 years. So there is a reasonable chance that a lamp will be discarded before the light from it has become unusable.

Lumens/W

lm / W tells how much of the power used by the light source is converted to light. The higher the value the better.

The old incandescent bulbs had a very low utilization rate or from 5 to 12 lm / W. Halogen bulbs have a higher utilization rate or around 17 - 25 lm / W. LEDs have an even higher utilization rate or range from 50 to over 100 lm / W. The theoretical limit on LED is around 300 lm / W. This means that when this limit is reached, using the 1.5W LED can achieve the same brightness as the old 40W incandescent bulb. A good rule of thumb is that a light amount of approx. 450 lm replaces a 40W bulb and lights of approx. 670 lumens replace a 60W bulb.

ODSIF's way of making good and comfortable colors

To make the white light, we use a white diode as the main light source. Our white diodes are quality diodes with a CRI value of 80 or more, and color temperature below 3000K.

In this way our light is a soft and comfortable light with all the necessary color components to be able to reproduce colors from the material or things on which the light falls. To shine this light, we use RGB quality diodes from eg. OSRAM. We tone the light by mixing the colors of the RGB diodes with the white light. In doing so, we maintain the high CRI value and can make light with different shades of color. Eg. when we make a golden light, we mix the white light with a strong red color, a little green color and a little bit of blue color.