Light is more than just vision. It includes aspects of well-being, health and emotions. At the same time our knowledge about how lighting affects people has increased significantly. Light emitting diodes (LEDs) as a digital light source offer new technical possibilities for fulfilling special visual, biological and emotional requirements. LED lighting products produce light approximately 90% more efficiently than incandescent light bulbs. LED lighting is finally coming of age, but many of us are still nervous of this relatively new technology. Lots of people tried LED lighting when it was first available and it often produced dim, cold puddles of light. Those memories still persist, so in fact a lot have to be done to pursue people that this is no longer the case. There are available a selection of LED bulbs with the range of colours, brightnesses, fittings and so on. That way we can get what we want without making costly mistakes and compromising on lighting outputs. To prevent performance issues, the heat LEDs produce is absorbed into a heat sink. LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light. This feature makes LEDs more efficient for many uses such as recessed downlights and task lighting. With other types of lighting, the light must be reflected to the desired direction and more than half of the light may never leave the fixture.
Instead of initial high cost factors, LED lights are on track to be the dominant form of lighting in the times to come with many advantages and only a few limitations. Efforts are going on to improve the LED lighting systems with a great expansion in their applications horizon. Global adoption of LED lighting technology can help save billions of dollars in electricity costs by diminishing lighting loads. With the use of LED lighting, diminished heat build-up in homes and offices can also diminish the need for air conditioning, further lessening demand for electricity. Modern LED technology is intersecting with the Internet of Things (IoT), assigning IP addresses to individual lights to allow lighting control through a smartphone app. It’s another step toward the smart home, in which users can control everything—lighting, heat, appliances, security features—from anywhere by the simple touch of a button. Pros and cons of LEDs can be summarised as shown in Table 1.
Applications of LED Lighting Systems
We need a product we can trust and will produce a good clean light for years to come and save money in the process. The LED market is highly saturated with manufacturers and distributors offering various levels of quality, cost, and specifications. LEDs are commonly used as indicator lamps in many devices but are also increasingly used for other purposes as well. Around the house, LED lights can be used as accent details for cove lighting or for highlighting a certain décor or architecture feature. They can be used to highlight a certain area such as the space underneath o above the cabinets, bats, sofas, tables, etc. They can also be used for cove lighting and can create a very interesting effect, especially at night. LED lighting is currently available in a wide variety of home and industrial products, and the list is growing every year. The rapid development of LED technology leads to more products and improved manufacturing efficiency, which also results in lower prices. Below are some of the most common types of LED products.
LED lighting panels
LED panels are becoming more popular than ever as they are extremely convenient, efficient, and easy to set up. But at the same time, there are some undeniable downsides to working with them. Certain LED panels can cause colour casting in footage, they are prone to flickering, and the quality of light itself isn’t as pleasing to the eye as tungsten or HMI lighting until it is modified. With all that the benefits of shooting with LED panels outweigh the negatives. They are so light and portable and can effectively allow shooting well in nearly any situation. In years past, to capture a night scene in a really dark exterior environment there was no choice but to rent a generator. Working with generators is cumbersome, costly, and very noisy. LED panels, on the other hand, can be powered with a single V-Mount battery, which in turn solves the sound issue. Not to mention they stay cool when working with them, making adjustments and teardown a breeze. Here are some tips for working with LED panels. Some of the performance issues with LED panels can be highlighted as:
As the LED gets dimmer and dimmer, there comes a point when it just cuts out (switches off). With cheaper fittings, this cut off is more pronounced and more visible. LEDs work successfully in lights with dimmer switches where many energy saving bulbs do not. Need is to get the dimmer switch changed to a ‘leading edge’ or LED compatible dimmer. This is because they handle much lower loads. Some bulbs have built-in circuitry to manage dimmers. They are no more expensive than ‘regular’ dimmer switches. Most LED panels these days have the option of dimming down the brightness, which is an excellent feature to have when it works. The problem however, is that dimming doesn’t always work well and many LED panels are prone to flickering when they aren’t running at full blast. Some of the higher end LEDs does a phenomenal job of maintaining consistent brightness when dimmed down to any level, but at the same time, a lot of LED panels do suffer from this issue. Sometimes the effect is so subtle that we almost don’t even notice it while shooting, but then in the editing room it becomes apparent. Although the LED fitting is connected to a control signal from the lighting desk, the electronics in many cheaper LED fittings do not allow them to dim completely smoothly, resulting in a ‘stepped’ dim, rather than a smooth seamless dim.
LED panels (like many other light sources) don’t typically generate very pleasing results when used directly. In other words, to simply flick on LED panel and point it at any talent, the overall quality of the light probably isn’t going to be what we’re looking for. Many corporate videos, events, and other lower budget productions mistakenly shoot this way with LED panels, and their footage can look very cheap. Instead, be sure to always use a modifier to soften up the light.
Incandescent (filament) light bulbs have a relatively slow heat up / cool down time. The light fades (over a fraction of a second) when we cut the power. However, with an LED, the light cuts off completely and instantly as soon as the power is removed. LED lights at 100% do not flicker noticeably, but as they are dimmed electronically, the flicker is visible to a video camera (if not to the naked eye). If an LED colour (in a cheaper fitting) is kept at a low level, the flicker will be very noticeable on video recordings. The higher the refresh rates of the LED, the faster (and less visible) the flicker. The flicker rate is measured in Hertz (Hz) – cycles per second. All LED panels are not made alike – especially when it comes to flickering. That same notion applies to other aspects of the lights as well, such as build quality, features, and colour casting.
LED light can appear cold and harsh – it lacks the warmth and subtlety of tungsten lamps. It seems to be another major issue for many panels. Much like fluorescent lighting, LED panels are often prone to outputting light with a slight colour cast that can make skin tones and other elements read strangely on camera. Colour correction can fix this to some degree, but for shooting with LED panels regularly it would be far better to actually have panels that don’t suffer from this issue.
Colour temperatures mixing
Many newer LED panels today give the option of mixing colour temperatures between tungsten and daylight. In other words, they will have two separate sets of LED bulbs (one tungsten colour, one daylight colour), and can not only choose to use either of them, but can use both in unison with each other. This is an amazing feature to have, but at the same time it is one of the most frequently abused features on LED panels.
LEDs in a stage lighting
LED fixtures designed for entertainment use are not the same as regular stage lights. They must not be connected to a dimmer. The electronics that run and control the LED fitting are built into it, and require a constant undimmed power source. A control signal must also be connected to each LED fixture, which comes direct from the lighting desk.
Some LED fittings are single colour, but most contain LEDs which can produce Red, Green and Blue light independently. These LED fixtures are known as RGB, and enable a wide range of colours to be produced on stage by mixing them together in varying amounts.
LED lighting strips
The use of flexible LED strip lights is rapidly rising in modern lighting design around the world. Architects and lighting designers are implementing LED strip lights into residential, commercial, and industrial projects at an increasing rate. This is due to an increase in efficiency, colour options, brightness, and ease of installation. A homeowner can now design like a lighting professional with a complete lighting kit and an hour or two. There are many options on the market for LED strip lights (also called LED tape lights or LED ribbon lights) and there is no clear-cut standard for how to choose LED strip lights. An LED strip light is a flexible circuit board that is populated with LEDs that can stick almost anywhere to add powerful lighting in a variety of colours and brightness.
Restaurant & Bar LED Lighting
LED strip lights provide a long list of benefits for restaurants of any variety, from small cafes to five-star eateries. They are aesthetically superior to traditional lighting, reduce monthly energy costs, and last up to 100 times longer than standard incandescent bulbs. Increased product development in recent years also means lower initial costs and easier installation, meaning inexpensive use of LED strip lights for bars and restaurants, particularly in dining rooms, lounges, or kitchen areas. LED strip lights provide highly elegant illumination in a three different tonal ranges; Natural White and Warm White options are particularly popular in commercial applications. LED strip lights come in a variety of single colours as well as versatile RGB, and these are great for creating a customised lighting experience in restaurant or bar. Since LED strip lights can be curved, cut, and connected to fit virtually anywhere, they provide attractive indirect lighting underneath countertops, around bar backs and even in hidden corners and alcoves. Another important advantage is that LED lights produce no excess heat, which further contributes to energy efficiency and makes them perfect for use in kitchens.
Cabinet & Ceiling LED Lighting
Adding high quality indirect light can bring almost any room to life, something astute designers and homeowners everywhere are discovering. Installing above cabinet LED strip lighting is a popular way to achieve this – it’s a simple, do-it-yourself project that will dramatically improve the visual appeal of any space. Indirect LED lighting provides a generous, warm glow that is strongly preferred over direct overhead lighting fixtures and bulbs. Small, versatile LED strip lights can be subtly attached to the top of any cabinet to provide a beautiful indirect light source without visible wires or compnents. It’s a perfect way to illuminate kitchen, dining room, or any above cabinet area in the office. Similarly, composed of a ceiling web of circular LED units, patterns and moods can be drawn into the ceiling via the light wand, which communicates with the sensor inside the LED unit. Users can set the light type as well as the colour for each unit across the whole ceiling.
Problems with LED lighting
The lighting industry is competing in terms of efficiency and new records are set frequently. The inconsiderate usage of the technological possibilities involves the danger of creating useless or very bad solutions that in the end raises questions about the complete technology. For example, the combined spectra of several LEDs entail the risk of being perceived as bad colour quality, or specific surfaces may seem unnatural. The combining of different colour LEDs can lead to irritating colour shadows, or the commonly used pulse width modulation (PWM) for dimming the LEDs can generate disturbing flicker effects with moving parts. The extremely high light density of high power LEDs can produce uncomfortable light pressure and strong glare in the radiation field. The quality criteria stated in relevant harmonised standards that are used in lighting engineering, are not suited for this kind of LED illumination. The LED is, at present, a product that is outperformed by a better LED within months. But at the same time it has a life span of several decades. All this generates large uncertainty with handlers and consumers and makes long term planning difficult. To use the potential of LED-technology in a positive way for the end-consumer, new rules (technical but also qualitative standards) are needed. The requirement, therefore, is, amongst other things, the establishment of new quality criteria to quantify these benefits.
Colour rendition (colour rendering index, CRI) is an important spectral quality criterion of a light source. This index tells us to what degree colours are rendered correctly in comparison to a reference light source (daylight or thermal radiator) when illuminated by an artificial light source. The early LED generations often had CRI values of less than 80 and thus did not meet the requirements stipulated in the standards for interior lighting. At the same time, it has been noted that the colour saturation of objects illuminated by LEDs, at least in part, appeared to be considerably stronger and also more appealing.
Dynamic artificial lighting
Generally dynamic lighting varies the lighting level, the distribution, and the colour temperature of an interior space. The transition of the lighting parameters occurs slow enough to be below the awareness threshold (subliminal) mostly lasting more than 15 minutes. The primary objective of dynamic lighting is either controlling artificial lighting in the interior subject to the time of day in order to facilitate certain specific non visual effects of light on mood, sleep, cognition and physical activity or supplementing missing natural light with artificial light with the aid of sensors in order to increase visual comfort and to establish an energy efficient means of adding artificial lighting. Currently the scientific evidence regarding the non-visual effects of dynamic light is quite limited. From a technical point of view, dynamic interior lighting can either be realised by mixing different colour LEDs with / without a white LED (RGB- respectively RGBW mixing) or by mixing white LEDs of different colour temperatures. Although the chromaticity coordinates of the resulting spectral distributions can be kept close to the black body radiation (Planck´s law), this method of mixing light does not represent a quality criterion for dynamic lighting per se. It is recommended to also spectrally evaluate the mixed spectrum by means of updated colour rendering computation methods.
Flicker is the temporal modulation of the luminous flux of a light source and can be visible or invisible. Flicker can induce epileptic seizures, headaches, fatigue, eyestrain, blurred vision, migraines, and distraction; reduce visual performance and altered perception of moving objects. Flickering light matters in applications with fast moving objects, where eyes have to move quickly (e.g. while reading or searching) and where video cameras are used. From a technical perspective flicker can be described in terms of its modulation frequency, modulation amplitude, DC-component, duty cycle and modulation waveform. The quantity of flicker for LEDs strongly depends on the used electric components and on the operating conditions (e.g. dimming). At the moment these details are not specified neither for LEDs and ballasts nor for LED luminaires and thus it is difficult to decide on the quality of products concerning flicker. Application-related factors which modulate the impact of flicker are the duration of exposure, stimulated retinal area, location in the visual field, brightness of the flickering light source, and local luminance contest of the light source to its surrounding.
Vision is strongly influenced by the luminance distribution in the field of view. Especially in sceneries with objects much brighter than the adaptation level of the eye these potential sources of glare can decrease visual comfort as well as visual performance. In a working environment this reduces productivity and in other applications like traffic it might even be a threat to human life.
Future with LEDs
The LED as a highly efficient and digital light source has triggered a rapid change both in the lighting industry and also in the implementation of illumination. With a common light yield around 120-140lm/W in realistic operation the LED already surpasses all other high-grade luminaries in general lighting. In the coming years the light yield will increase up to around 200 lm/W. At the same time the life span of 50,000 hours outperforms conventional luminants by far. Therefore although the initial costs for LED lighting systems are higher, due to the longer life time, the profitability outperforms that of most customary systems. The characteristic of LEDs to respond to control signals instantaneously, meaning without time delay, is ideal for usage in communication technology. The combination of LEDs with light- and movement-sensors, interconnected with complex control and regulation algorithms, turn the lighting into a smart and adaptive system that can react to alterations in its environment (time, weather, etc.) in a flexible way. A future vision is an autonomously acting “thinking” LED-luminaire, that is integrated into a higher-ranking information and communication network over the “internet of things”. Merging several colour LEDs to a single spectrum, while each LED is dimmable, allows the luminous perceived colour to be set in an almost user-defined manner. In so doing, lighting systems can be fashioned with which the perceived colour, the intensity and the light distribution can be dynamically modified for each use case or individual requirement. LED-technology in cooperation with communication technology offers new possibilities for high grade and individual lighting solutions. To create a sustainable benefit for the users, generally acknowledged criteria must be set up, with which the new qualities of light can be assessed and measured. Furthermore, the non-visual effects of light on the human being must be better understood to be able to create “healthy” light. The lighting community is facing the unique challenge of changing the value of lighting in society from an understated and cheap topic to an important and well-noticed issue regarding life quality, health and life style. And, without any doubt the LED-technology provides the potential to cover the increasing need for light while at the same time reducing energy consumption.
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