WHAT IS AN LED?
Almost all of us have sometime heard talk about or seen an LED, for example, as a blinking light in our TV. LED stands for Light Emitting Diode, and it is a source of generation of light that is developed through materials and technologies used in the manufacturing processes of electronic chips..
HOW HAVE LEDs EVOLVED?
LEDs have progressed a lot since the appearance of first red LEDs in the 60´s, passing through red LEDs in the 70´s. The appearance of red LEDs in the early 90´s brought about the possibility of creating white light through LED technology. However, all of these types of LED had a common disadvantage: the lighting power was very low, which limited their application to just signalling purposes.
Thanks to the fast advance of the different electronic technologies and of generation of semiconductors, the creation of LEDs with capacity to generate light took place in the late 90´s. For this reason, these LEDs were denominated “high power LEDs”. |
¿WHAT ADVANTAGES DO LEDs PROVIDE??
Just as its functional point of view, luminaire development and applications of light, the numerous advantages of High Power LED as a light source make it progressively substitute whichever other conventional light emitting technology such as incandescent lights, discharge lights or florescent.
Hereafter we will detail the principal characteristics that are attainable with the design capabilities, conception of products and new applications for illumination never before though possible.
DURABILITY
When the High Power LED is correctly applied, the light flow depreciation reaches the order of 50,000 hours while maintaining 70% of the initial flow. To this factor we need to add a very low probability of failure during the first 100,000 hours of use. Compared to conventional incandescent lamps, florescent and discharge lamps have a very high probability of premature failure. The usage of LEDs means a drastic reduction of the costs of maintenance in light application as well as makes possible the incorporation of light in products where the need for maintenance through lamp replacement could be critical.
ENERGY EFFICIENCY
The energy efficiency in light applications with LEDs is up to 4 times superior to that of conventional technology existing today, making possible the creation of products with very low consumption.
ENVIRONMENTAL PRESERVATION
Contrary to other conventional lamps such as fluorescent and discharge lamps, the High Power LEDs do not contain mercury or toxic gases and are lead free, complying with the most demanding regulations, such as RoHS and WEEE, and contributing to the preservation of the environment.
COLOUR
LEDs also present a new variable in illumination: the control of light and its tone. If there is one thing that LEDs have proved efficient in since their origin is the generation of colour light without the need of costly and inefficient filters. This creates new possibilities of usage as light decoration, while permitting the adaptation of the tone of light necessary for the users, giving way to the generation of any colour visible in the light spectrum.
ELECTRONIC TECHNOLOGY
The LED is as electronic as much as any other equipment of control and source of power. This permits the regulation of light intensity from the moment of shut off until the point of 100% light flow with some possibilities of digital control unattainable with conventional technologies. The switching on an off can be instantaneous or regulated in very extreme conditions, from -40ºC to +120ºC. This makes possible the introduction of dynamism in illumination just as the adaptation and interaction of the light with which we live in our luminous environment. The fact that it is a solid electronic device also provides excellent characteristics of toughness and insensitivity to vibrations.
LIGHT CONTROL
Due to their small size, the High Power LEDs allow for control over their light generation much more than existing conventional technology, while permitting their integration in reduced spaces. Depending on their application, and after an adequate design of optical system, a great increase of energetic efficiency can be achieved in the application of light, while allowing a drastic reduction of dazzle and light pollution.
NO UV OR IR EMISSION
The radiation generated by the LEDs is only the visible light since it does not emit ultraviolet or infrared radiations. Due to these characteristics, the radiation that emits does not produce the warming or the deterioration of the objects that it illuminates, making LED lighting a great choice for illumination of art works, fabrics, cosmetics, plastics, food, drinks, etc.
LOW POWER VOLTAGE
This makes LED technology especially adequate for its usage in underwater applications, in boats, automation and aeronautics, as well as places where the electronic security and the minimization of risks to people are critical issues. At the same time, its utilisation with sources of renewable energy is very adequate, such as solar panels or wind power generators, since they generate electrical energy at low voltage. This way, the power supply of LEDs is feasible without the need of wasting energy with electrical transformers. |
Thanks to our visual organ, the eye, we can detect Light. The eye is composed by a complex system that is sensitive to light changes, capable of transforming these impulses into electrical impulses.
The interior of the eye is a dark cavity that has to avoid that light enter through and reflections and illusionary images be produced. The pupil is an opening that permits light pass into the interior of the eye. It is controlled by the iris, which is the muscle that makes the pupil dilate or contract according to light exposure. The iris at the same time is covered by the cornea, and the lens of the eye is situated behind the iris. This lens has the function of focusing the light into the retina, which acts like a screen. The retina converts these images into neurological signals.
The essential factors in the conditions that affect the vision are the distribution of the light and the contrast of the luminance.
There are two types of light sensitive cells in the retina: the cones and the rod cell. The rod cells are used for the vision in black and white, and they are concentrated in the sides of the retina. The cones are used for colour vision and are concentrated in the centre of the retina. There are three types of cones: sensitive to red, sensitive to green and sensitive to blue light.
The visibility of an object can be altered in many ways. One of the most important is the contrast of lighting due to factors of reflection, to shadows, or to the colours of the object itself and to colour reflection factors. What the eye actually perceives are the differences in luminosity between an object and its environment or between different parts of the object itself. |
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Light is energy in the form of electromagnetic radiation in the wavelength range 380nm - 770nm, which is what our visual system is able to perceive.
Colour is the interpretation that makes our visual system of the structural composition of the light detected by the eye. Every illuminated surface absorbs all or part of the electromagnetic radiation and reflects the rest. The colour which we perceive depends on the amount of light that is emitted, reflected, transmitted and absorbed by each wavelength in the visible spectrum.
The human eye only perceives colour when light is abundant. With little light we can see black and white. White colour is the result of the combination of all the colours, while black is the absence of light.
A white light can be separated in all the colours of the spectrum by a prism. In Nature this separation occurs in a rainbow. The temperature of the colour is a parameter which is used to indicate the tone of white light for the comparison of a black body at that temperature. Meanwhile, the chromatic reproduction index indicates the capacity of a light source to reproduce colours of illuminated objects.
Colour is artificially generated by the combination of the primary wavelengths: red, green and blue, keeping in mind the characteristics of our visual system. Colours are classified in groups: warm (yellows and reds) and cold (greens and blues). The CIE (International Commission of Illumination) has defined as a standard of identification the chromatic colour diagram CIE, where each colour is represented by the coordinates X and Y. For objects which are not light emitters, colour can also be generated by absorption, emission or addition of wavelengths.
Colours produce some physiological and psychological effects over people such as:
Sense of warmth: warm colours (from red to yellowish green). They are dynamic, exciting colours that produce a sensation of closeness.
Sense of cold: cold colours (from green to blue). Colours that calm and rest, producing a distancing feeling.
Purity or saturation of colour: the clear colours animate and give the sensation of lightness, while darker colours depress and give a slowing feeling.
Harmony: is produced when two or more colours are mixed with a nice effect.
Recent studies have demonstrated that the colour of Light produces alteration in the cardiac rhythm and facilitates the conciliation of dreams. |
The purpose of an optical system is to distribute in the designated area the emitted light by its source. To accomplish this, reflection, refraction and the dispersion of light are used by its own materials. Generally they are composed of aluminium because of its high reflectance and glass and transparent plastics for its high transmittance capacity.
It is important to plan and care for the form and the distribution of light in respect to the design of an optical system, the performance of the lamp - luminaire assembly and the dazzle it could cause to the users.
The design of an optical system consists in the generation of reflective and refractive surfaces that redistribute the radiation emitted by the lighting system until the desired photometry is reached. Photometry consists on the reproduction of a pattern of illumination and is just the representation of intensities in space. |
In the highly developed countries approximately a third of the energy consumption is produced through electricity, in which 25% is directly associated with illumination. The cost of illumination can represent up to 80% or 90% of the operating energy costs in commercial applications.
The current conventional lighting technologies are actually highly inefficient presenting a proportion of useful energy conversion which would barely reach the 15% being optimist, and reaching the value in the order of 2% in a larger part of these. In comparison, the use of energy for heating in buildings, or motors, is much more efficient with values of 70% or 90% respectively.
LuxInTec´s technology is developed with the purpose of join electronics and illumination, and the increase of the energy efficiency in the application of lighting. For this we consider not only the efficiency in lm/watt ratio of the lamp, but also the sum of this efficiency in the electronic power source, the optic control of light generated and its correct projections in the installations. From an environmental point of view, the energetic consumption at a global level in the year 2005 generated the emission of 9 billion tons of CO2 into the atmosphere. The development or implementation of lighting technologies of illumination using potency LED reflect a step forward in the reduction of energy consumption which would permit the duplication of efficiency in the application of the light for illumination by the year 2025.
Furthermore, thanks to the LED technology there will be a drastic reduction in the light pollution of cities, due to the control of light that this technology allows to attain. This pollution is the direct or indirect emission towards the atmosphere of light originated from an artificial source, due to the use of inadequate or excessive illumination. The most notable effect of this pollution is the dispersion of light towards the sky, in other words there is no control of light intrusion and its abuse, which directly threatens the biodiversity of nocturnal animal and plant life which rely on the darkness to survive and maintain their equilibrium, also like the persons who see as their homes are invaded by the street lamps out of control. |
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