Lumistrips LED Lighting Blog

The illuminated ceiling or stretch ceiling is very interesting trend in interior lighting. By using a translucent material many square meters in size with a backlighting system, a diffuse, even and relaxing illumination of interiors can be created. The main advantage of this type of lighting is the absence of glare, as the light sources are distributed over a large area and hidden behind the material.

The backlight source is usually low or medium brightness LEDs (5 to 50 lumens) mounted on strips or modules. Since the illuminated surface has a large area, such low power illumination is the best choice.

Illuminated stretch ceilings can have personalized shapes and even feature translucent images. They can therefore influence the overall design of a room much more than other lighting fixtures. From a lighting design perspective, uniform light should be supplemented by spotlights or lamps that can draw attention to specific areas or objects.

The proper design and installation of a luminous ceiling has a number of unique challenges that we will address in this article.

Human Centric Lighting is lighting specifically designed to produce a beneficial physiological and/or psychological effect upon humans. White LED lighting solutions are adapting the light color and intensity during the course of the day, so indoor lighting is similar to that outside. These products are named tunable white LED lighting solutions.

Human Centric Lighting (HCL) supports human health, well-being and performance by implementing the light system according to the desired visual, emotional and especially biological effects of light.

The main focus of Human Centric Lighting is to be focused on people's needs for their living, leisure and working environment, by taking in account the effects of natural light, a dynamic source with changing tone and brightness, as a day goes by and seasons change. 

To implement an adequate Human Centric Lighting a combination of white LED light sources is used, usually warm white (2700K) and cold white (6500K). This is Tunable White lighting.

By adjusting the intensity of each, bright or dim white light with a hue between 2700K and 6500K can be obtained. 

Lines of light are a new trend in lighting design and are usually made with an LED strip inside an aluminum profile that has a translucent white cover. The attraction of using such a linear light fixture is that it can be personalized. You can choose as you desire the pattern, place of installation, length (up to many meters), geometric shape or a combination of these elements.  

Because of their way of construction lines of light are a type of direct lighting. Compared with coves that are indirect lighting, lines of light are more energy efficient but can have greatly increased glare. For this reason lines of light should be designed with care and almost always be dimmable. 

Let's see how we can achieve the best results with lines of light.

The positive health effects of the full spectrum SunLike LEDs from Seoul Semiconductor have been confirmed in two independent studies, by universities from Switzerland and South Korea.

The new SunLike LED technology brings a major improvement to the spectral power distribution (SPD) of LED lights, which now mimic the SPD of the sun within the bounds of the human visual range. The SunLike LEDs use a three-phosphor mix and a violet emitter to achieve the SPD. Seoul has said that the LEDs can be used in a variety of applications including in human-centric lighting or lighting for health and well-being where tunable lighting can be applied to improve human well-being.

A study published by the University of Basel in Switzerland titled “Effect of daylight LED on visual comfort, melatonin, mood, waking performance, and sleep” found that volunteers had better visual comfort, more alertness, and happier moods associated with exposure to SunLike LEDs compared to other LEDs. 

Luminous flux is the measure of brightness of a light source in terms of the energy emitted in the form of visible light. Luminous flux, in SI units, is measured in the lumen (lm). 

Depending on the application, luminous flux can be measured per lamp, fixture, per linear meter or per square meter. For lamps the most known is the luminous flux of the light bulb, in all its variants (incandescent, fluorescent, LED).

Nichia's Optisolis innovative white LEDs use a special blue LED chip and a new high-quality, phosphor devoped with Nichia's proprietary technologies and extensive expertise. Their light spectrum closely matches the spectrum of natural sunlight, renders colors accurately and adds the benefit of increased awareness of contrast and texture.

The new SunLike LEDs from Seoul Semiconductor are the world’s first natural spectrum LEDs, as they produce light that closely matches the spectrum of natural sunlight. This is made possible by using a the TRI-R technology new LED architecture, with a purple emitter in combination with a red, green, and blue (RGB) phosphor mix, unlike conventional white LED that use a blue emitter and yellow phosphor. 

This new design makes possible for an LED to render colors very accurately, almost as sunlight, with the added benefits of increased awareness of contrast and texture.

The high quality of the SunLike LEDs light spectrum is expressed both by the traditional color rendering index (CRI) and the new Color Fidelity Index. Therefore, SunLike LEDs have CRI 97+ and  Rf 96(TM30 Fidelity Index), values that indicate the high accuracy of reproducing the original color from 99 representative color indexes.

The Color Rendering Index, commonly referred to as CRI, is a method by which we can measure how color looks to the human eye, depending on the light source compared to the sun. The CRI offers a scale of values up to 100, where 100 is the best color rendering light quality and a value below zero is a very poor color rendering. The higher the CRI value (also called CIE Ra), the more accurate the colors are.

If a luminaire has a CRI of 100, this means that there is no difference in colour rendering between the light and the reference light (the sun). Likewise, a CRI of 75 means that the light bulb reproduces a 75% replication of the visible colors that the sun shows, since both lights have the same color temperature. This means that if the reference light is the light of the sun during sunset, the light source to be measured must also have the same color temperature to allow the most accurate comparison with the CRI measurement.

To obtain white light from an artificial source, a combination of different emitted wavelengths is required, something that was discovered at the beginning of the 20th century.  From then on many "recipes" to produce white light and combine the  different wavelengths were invented and still are.

Nichia Optisolis LEDs with the full spectrum of sunlight

The latest innovation in LED development is the Optisolis technology form world market leader Nichia. Optisolis™ LED emitters provide a natural light source with a spectrum which achieves the industry’s closest match to that of the standard illuminants, sunlight and incandescent artificial light, having a CRI higher than 98.

Industrial scale indoor agriculture under artificial lighting in closed and fully controlled environments could become the main factor that keeps at bay famine and related conflicts. With increasing population, diminishing area of agricultural land, pollution, global warming and migration to grow plants in a reliable, predictable and efficient way will become even more important in the future. For this reason it is important to understand and corectly apply the concepts of lighting for plant growth and development.

Concepts related to Horticulture lighting

A key factor in the success of indoor plant growth is the efficiency of the lighting system compared with sunlight, in the process of plant growth.

Plants grow via a process called Photosynthesis that converts electromagnetic radiation (light) into the chemical energy needed for growth and development. The other ingredients required are carbon dioxide (CO2), nutrients and water. 

Photosynthesis and PAR radiation

The electromagnetic radiation required for Photosynthesis is defined as photosynthetically active radiation (PAR) and 400 to 700 nanometers has spectral range. Only radiation in this interval can be used by photosynthetic organisms in the process of photosynthesis, to fix the carbon in CO2 into carbohydrates.

Electromagnetic radiation called visible light or simply light for a typical human eye has a spectral range from about 380 to 740 nanometers.

A common unit of measurement for Photosynthetically active radiation PAR is the photosynthetic photon flux (PPF in short), measured in units of moles per second. For many practical applications this unit is extended to PPFD, units of moles per second per square meter.

The theory behind PPF is that every absorbed photon, regardless of its wavelength and energy, has an equal contribution to the photosynthetic process. As in accordance with the Stark-Einstein law, every photon (or quantum) that is absorbed will excite one electron, regardless of the photon’s energy, between 400 nm and 700 nm. 

However, only some of photons are absorbed by a plant leaf, as determined by its optical properties and the concentration of plant pigments. The pigments are Chlorophyll A, Chlorophyll B, and Carotenoids (a/-Carotene, Lycopene, Xanthophyll).

The Chlorophylls A and B give plant leaves the characteristic green color because they reflect most of the radiation between 500 and 600 nanometres.  Plants Where more Carotenoids than Chlorophylls are present plant leaves reflect wavelengths beyond 540nm and have yellow, orange, and red colors. This includes autumn leaves when Chlorophylls have dried away. 

The graph below shows the typical absorptance spectra for Chlorophyll A, Chlorophyll B and Chlorophyll (beta-carotene). Each are explained briefly afterwards: