LED Linear™ Technology
All you need to know about LED tapes and the LED Linear™ difference!
FLEXIBLE LIGHT ENGINE PRODUCTION METHOD - REEL to REEL vs SHEET to SHEET
What influence does the production method have on the quality of the light source?
SHEET to SHEET Method
As the name suggests, this method involves overlapping individual LED sheets and repeatedly soldering them together in order to achieve longer lengths of LED tape.
These soldering points do not have proper contact with the heat sink. The heat from the LEDs cannot be dissipated effectively and the product degrades faster. These substrates are also less flexible, with each connection representing a weak point at which the LED tape may break causing an interruption to the electrical current.
REEL to REEL Method
This method starts with the substrate reel. In this fully automated process, the substrate is printed, equipped with LEDs and the electronic components with a precise pick and place process, controlled and cut into individual full tape lengths. In the end, the finished LED tape is wound onto a new reel that is ready to be shipped or assembled into a finished luminaire.
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THERMAL MANAGEMENT
For a more reliable light source!
Thermal management has a huge impact on various aspects of the LED light source. A common misconception is that an LED light does not get warm, however, when placed on a considerably smaller substrate, thermal management becomes a critical concern for luminaire design. With adequate heat dissipation, the aging and degradation of an LED can be significantly slowed down. This means that intensity, homogeneity and color properties of the LED chips remain stable, thus ensuring a longer lifetime and better durability of the luminaire. This technology enables high power in small profile luminaires.
Some materials dissipate heat away from the LED chip better than others. Many manufacturers use versions of PCB plastics as substrates for their LED modules. Plastics, among others, have poor thermal conductivity, which means that heat accumulates causing the LEDs to heat up more quickly.
LED Linear uses a proprietary substrate that draws the heat away from the source and transfers it to high quality aluminum profiles. The heat does not stagnate in the luminaire, but is transferred and dissipated through the heat sink into the air and/or the materials the luminaire is mounted on. The LEDs degrade much more slowly than competitive fixtures and their quality is maintained for a longer period of time.
Color Consistency
What influence do binning and color shift have on the light source?
The topic of color consistency of LEDs is even more important in linear lighting considering the number of LEDs on the light line. A high level of color consistency is required at day one (Binning) and later after the installation (color shift). All LED Linear™ products feature color consistency. This is of great advantage for instance for long light lines like ADONIS True Color and/or VENUS True Color.
- What is binning?
- What is binning tolerance?
LEDs have different colors due to production tolerances. It is important to sort them into so-called “bins” to make sure. This binning structure follows the MacAdam ellipse metrics which guarantees no visible differences if within 3 step MacAdam (SDCM3). The lower the number, the tighter the binning, and thus the higher the value of an LED chip. To obtain a color impression that is as homogeneous as possible, only LEDs of the same binning should be used.
This is the measurement tolerance the LED manufacturer can ensure in sorting the LEDs into bins. If the tolerance is bigger than 0.003 then the LEDs are not strictly within the 3 step MacAdam. If not stated, LED Linear only uses LEDs for which the LED manufacturer can ensure a SDCM3 binning with a 0.003 tolerance.
Light Homogenity
What influence does the electronic design of the LED tape have on the constant brightness and thus on the quality of the light?
- Low-Quality-Tape
- High-Quality-Tape
- Lumen output over time
Fewer electronic parts are installed on low-quality LED strips in order to save costs. For example, these tapes use only one resistor per step length – a group of LEDs on the strip. Part of the incoming current flows back through the resistor causing less current to be transported to the other LEDs. The LEDs behind the resistor, therefore receive less current and thus have a lower lumen output. Extrapolated to a long length of an LED tape, this power drop becomes visible to the eye. With a length of 7 meters (23 ft), there can be a loss of brightness of more than 25%.
On an LED strip of higher quality, more electronic parts are installed per section. For example, a separate current regulation (IC Driver) per step can be integrated, which sets the current evenly for each step and each LED. This prevents a drop in power allowing the LED tape to maintain the same intensity over its entire length.
The lifetime of an LED tape is usually specified in such a way that a certain percentage of luminous flux is present after a certain number of hours. E.g. 60,000 h L90 means that after 60,000 hours 90% of the original lumen output is still present.
This is measured according to the IES LM80 method. This method outlines the procedures of actual light output testing of LED chips e.g. for 10,000 hours. These measurements are then extrapolated in the IES-TM21 calculation by max. 6 times related to the real measured time. This way you get the lifetime after 60,000h.
This information is particularly interesting for projects if a certain amount of light has to be present after a defined time - for example in an office application. The difference between 60,000 h L90 and 50,000 h L80 does not sound like much at first. However, if you compare their light output at the same point in time, e.g. at 60,000 hours. The difference can become obvious as seen in the comparison chart below.
All LED Linear™ products ensure a homogeneous light which is important for cove or indirect lighting utilizing low profile luminaries such as XOOLINE.
6 DIGIT PHOTOMETRIC CODE
How can the photometric code give an indication on the quality of the light source?
In addition to CRI and color temperature, the extended photometric code provides information about binning of the LEDs in time. On every LED Linear™ specification sheet, information about the tapes are given by this extended photometric code.
The first digit stands for the CRI value. "8" stands for a value between 77 and 86. "9" stands for a value from 87 to 100.
The following two numbers indicate the color temperature. In this example, 27 stands for 2700 Kelvin.
The extended photometric code starts from here on. The first number indicates the initial binning e.g. 3 for SDCM3.
The second number indicates binning after 6,000 h. If this value is identical to the value of the initial binning, it can be assumed that the binning will continue in the further course the quality is guaranteed. If for example, there is a 5 (SDCM5) instead of 3 (SDCM3), the color homogeneity of the LEDs will decrease over time.
The lifetime of the LED can be read from the last digit. The "9" is in this example of the abbreviation for L90.
Color Rendering
How can you measure how well a light source reflects the colors of an object?
- R9 – CRI Color Rendering Index Color Panel
- TM30-15
With this method, the color rendering of 14 colors is tested according to DIN 6169. The color rendering of the sun (100%) serves as a reference value. Particular attention is paid to R9 – saturated red color. R9 is an important metric for artificial lighting as most LEDs lack the red compared to reference light sources like the sun. A higher R9 ensures that the perception of the light is more natural than synthetic. The higher the value, the better the color rendering. The higher the value the more appealing the red apple looks.
The TM30-15 report is a novel method to measure color rendering. It also takes the sun as a reference value of 100. 99 colors are tested with this method instead of 14, thus an expanded spectrum can be analyzed. The average of all 99 colors results in the Fidelity Index Rf. In this example, the difference can be seen particularly well in the red/orange and pink skin tones. Another component of the TM30-15 method is the gamut index Rg which measures the saturation of colors within the same color spectrum. The ideal value for Rg is 100, but the measured value can be both below and above 100. A perfect light source would have a value of 100 for Rg and Rf.
Good or high color rendering is recommended in areas where products are illuminated. Best examples are museums, art galleries, as well as retail stores.
LED Linear™ proposes various color rendering options from CRI 80 up to CRI 97 like VarioLED™ Flex SOL and all Ultra High CRI fixtures.
REEL to REEL Method
The advantage of this method is the continuous substrate. There are no weak points on the LED tape leading to dramatically reduced chances of failure. There are automated checkpoints within the line throughout the entire production process. This way, any irregularities can be quickly identified and corrected.
This highly automated process enables the assembly of more than 45,000 components per hour through seven simultaneous activities and meets the highest demands on the quality of the LED Linear LED Flex Tape series. This mode of production not only enables highly efficient and fast production, but it also guarantees the highest quality and clear batch tracing through the printing of the production code on each reel of tape.