Scott Hanna, Executive Vice President, Lutron said: “Lutron remains committed to introducing continuous advancements to the lighting control industry. The Dalia dimmer takes Lutron’s classic rotary dimmer design and updates it with a new look, SoftGlow locator light, and superior dimming capabilities for dimmable LED, incandescent, and halogen bulbs. We believe our customers will appreciate the timeless, updated aesthetic combined with the latest dimming technology.”

The Dalia dimmer works with existing wiring and doesn’t require a neutral wire. It’s also easy to adjust the dimming range and improve bulb performance with a simple low-end trim lever. The SoftGlow locator light helps you locate the dimmer in the dark.

SubstiTUBE T8 Connected LED tubes function as a smart light eliminating the need for programming or rewriting which in turn saves time and labour cost. The communication of sensors and SubstiTUBEs via new ZigBee 3.0 standard enables approximately 200 devices (Tubes and sensors) to be wirelessly controlled, extending the presence detection and the corresponding automated lighting to cover large areas. For instance, with sensors at various entrances and exits, the tubes can be automatically turned on in sync if someone enters the premises through one of the entrances. Therefore, the SubstiTUBE T8 Connected is ideal to meet the specific and demanding lighting requirements in car parks.

The new SubstiTUBE T8 Connected features a Master and Slave mode for multizone control. The factory setting of the multi-sensor is the slave mode, but it can be configured to be a master sensor during the network installation.

Multi zonal dimming, occupancy sensing and daylight ambient setting, the intelligent system of new SubstiTUBE T8 Connected and sensors achieve significant energy savings of 50% or more compared to conventional fluorescent lamps plus additional 20% to 30% via connected sensor.

The SubstiTUBE T8 Connected comes in glass design with shatter protection film, high efficiency of up to 150 lm/W and a lifetime of up to 50,000 hours. The tubes are available in lengths of 1,200 mm and 1,500 mm with a five-year guarantee.

Shifting to pleasing, warmer hues as light intensity decreases, Soraa VIVID-Warm Dim maintains the high colour quality that Soraa is known for. Ideal for environments that require warm dimming capability, Soraa VIVID-Warm Dim lamps are suitable for new construction and are a perfect choice for relighting existing installations.

“Adding warm dimming capabilities to our VIVID lamp portfolio showcases the power and versatility of Soraa’s signature lighting technology in an elegant form factor suited for every lighting designer’s repertoire,” said Dr. Kieran Drain, President and COO of Soraa. “These lamps were designed for projects that require beautiful light quality in warmer hues, which is why we made no compromise in the design of these products.”

Soraa VIVID-Warm Dim lamps feature new market innovations with three different types of LEDs in a 24-array configuration we call Soraa MOSAIC technology to achieve smooth beam edges with the industry’s only 24 package design, which is 5 times greater than any other competing warm dim lamp available today. The result is a remarkably consistent light distribution, beautiful beam spread, and high-definition colour and white rendering capabilities.

The Bluetooth mesh standard was approved in July 2017 by the Bluetooth Special Interest Group (SIG) and offers a number of advantages for wireless lighting controls. The mesh architecture is inherently reliable with built-in failover so there is no single point of failure and luminaires fitted with the Bluetooth Bridge can be added or removed without disruption. Bluetooth mesh also is secure and highly scalable so it can connect thousands of nodes, and it provides a full stack communications protocol platform so it can support the Internet of Things (IoT) devices as part of the network.

There are 32,000 corporate members of the Bluetooth SIG, and any compatible device that has been qualified by the SIG can connect to any other Bluetooth device over Bluetooth mesh. For example, luminaires equipped with Fulham’s new Bluetooth Bridge can be controlled wirelessly by other Bluetooth devices, such as the EnOcean Bluetooth energy harvesting wall switch (also available from Fulham).

“Bluetooth mesh shows great promise for the lighting industry, making it an ideal solution to add wireless lighting controls as part of new installations or LED retrofits,” said Alvaro Garcia, Senior Director, Product Management, for Fulham. “With our new Bluetooth Bridge, installers can convert any 0-10v dimmable LED luminaire into a Bluetooth mesh node. Since Bluetooth is a recognised standard, we anticipate a number of manufacturers will develop their own BLE lighting solutions, and our new Bridge products make it possible to add any LED luminaires to the mix.”

Benefits will definitely increase when all these improvements are considered together during the planning and design stage or later in the existing homes. For instance, it is a common known fact that more efficient lighting always reduces the air-conditioning load. If you are focusing on lighting, consider replacing old appliances with energyefficient ones: The most efficient appliances in the market are labelled with Energy Star showcasing one to Five-Star ratings (higher the star, higher is their energy efficiency).

While preparing the lighting strategy, you choose depends on the level of remodelling you are doing, following few basic key design principles will definitely help:

1. Focus your effort on rooms used most

Improving the lighting in the rooms/areas which are utilised maximum throughout the day like in maximum cases bedrooms, kitchen etc. will definitely make a lot of difference. Every household has different activities happening depends upon many factors. For instance, a two-bedroom house with only two members and both are working will utilise the bedrooms and kitchen mainly for the five or six working days of a week, that too after their working hours. In the same way a five-bedroom house with seven members with two housewives and two kids will utilise the lobby or drawing room area on a regular basis throughout the day. So, while developing the lighting strategy, it is important to focus on the rooms or areas which are probable to utilise more depends on the activities. Refer image 1 for a photograph showing the regular use kids play or common area in a house; beautifully lit throughout with minimum utilisation of artificial lights.

2. Replace existing Light Fixtures

Most existing homes have incandescent or hot-intensity fixtures. Replace them with dedicated, hard-wired fluorescents or LED for betterment. If you use screw-ins, they may be switched back to incandescent when the bulb burns out, losing the energy efficiency benefits. Generally hard-wired fixtures and LEDs have better aesthetics and light quality, too. As shown in image 2, one can see the difference in colours of a same room just by replacing the light fixtures.

3. Layer lighting for maximum impact

To produce dramatic effects, design ambient, task and accent lighting in any area, ambient lighting provides general room illumination and may also reduce the need for additional portable lighting. Task lighting sometimes helps home owners to see better where they need it. For instance, cove lighting under upper cabinets in the kitchen to help lighting the kitchen during preparation of meals. Accent lighting adds sparkle by focusing on an architectural detail such as a fireplace or on photos or artwork or something else. See image 3 for a picture showcasing the only desired light in the activity area of a kitchen during preparation of meals.

4. Consider the room’s function and its form

No matter where you start, consider which activities are most important for your room. Perhaps the easiest place to begin in any house is the kitchen. As stated above, undercabinet lighting provides task lighting. When there is space above kitchen cabinets, between cabinet and ceiling, it’s easy to mount inexpensive strip lights to provide excellent, glarefree light for the entire kitchen. A recessed downlight over a kitchen area will accent the area, and at the same time help the user to see better when performing kitchen tasks and provide ambient light.

For the family room or lobby area, one can use a combination of ambient, track and portable lighting. In the washroom, both appearance and safety are important. At the appearance, light from either side of the looking mirror, as well as from the top, should not be there to avoid shadows inside the washroom.

5. Use concealed light sources

By using concealed light sources, one can notice the illuminated floors, walls and ceiling of the room instead of the direct glare of light bulbs. Concealed light sources help eliminate direct glare from lamps. Concealed lights can be utilised in the common areas or bedrooms also for better light efficiency. Refer image 4 for a picture showing well illuminated common room with the help of concealed light sources.

6. Use fluorescents or LED lights

According to a research, fluorescents use 25 per cent to 35 per cent of the energy used by incandescent to give the same light output and last up to 10,000 hours, compared with 1,000 for the typical incandescent bulb. Using a combination of fluorescents and incandescent lamps is likely to be less efficient than using all fluorescents or LEDs.

Most people associate fluorescents with the harsh, bluish lighting typically found in garages and basements. But for a nice, crisp light quality, as good as incandescent, choose fluorescents with a colour temperature of 3,000-degree Kelvin.

7. Limit the number of different light sources

Always try to avoid multiple types of lights in the house which will directly affect the energy utilisation in the house. For linear fluorescents or LED, use two different ones (3-foot or 4-foot length) and for CFLs use 15, 26 and 32 watts. This makes it easier for home owners to replace the lamps without much difficulty.

8. Consider control

Always consider the controls such as photo sensors, occupancy sensors, dimmers and remote controls which may help to reduce energy by ensuring that lights are only used when needed. Nowadays, automatic sensors are widely utilised to save energy but is costly than the other systems. One can choose wisely after considering short-term and longterm effects and benefits. Refer image 5 which showcasing the benefits of motion sensor lighting in the home by lighten up during activity time only. By applying these few key basic design principles during planning a house and also in the existing homes, the house owner can reap the benefits of effective lighting as well as energy efficiency by reducing the electricity bill and saving money in short- or long-term.

In today’s large-scale projects such as office buildings, museums and conference centres, light control systems are usually planned in from the start. However, wireless light control solutions are becoming increasingly popular that can be simply installed and even upgraded, quickly set up and also operated by non-technical personnel. The application frequently focuses on a limited room situation, but can be expanded if needed. Typical examples of such applications are exhibition spaces, art galleries, boutiques, restaurants and residential situations. With Bluetooth-capable luminaires in its Optec, Parscan, Oseris and Pollux spotlight ranges, ERCO now offers the ideal solution for such projects – an innovative approach for using light highly simply, costefficiently and at a professional level as a scenic and dynamic tool of design.

Bluetooth – integrated in the control gear

ERCO technically implements this concept by integrating Bluetooth technology from the Finnish company of Casambi directly into its control gear developed and produced in-house. The luminaires equipped in this way communicate with each other as well as with compatible smartphones, tablets and Smartwatches via the Bluetooth LE radio standard, with luminaires then being controlled over the Casambi app on the mobile end device.

The range of functions on the app includes switching and dimming single luminaires, grouping luminaires and setting up light scenes. Intuitive operation is provided by a visual user interface from ERCO with a simple, clear design. The luminaires form a so-called ‘mesh network’ that can also include the compatible products of other manufacturers, and such mesh networks can be independently set up in any quantities and linked with applications on the internet via gateways.

Available for a wide range of luminaires

Thanks to the ERCO system of luminaires a wide selection of Bluetooth-capable luminaires for track are already available. The product ranges Optec, Parscan, Oseris and Pollux offer various, attractive design options at wattages to 19W. These ranges feature interchangeable lens optics with rotationally symmetric light distributions of narrow spot, spot, flood, wide flood and extra wide flood, oval flood axially symmetric light distribution and wallwash asymmetric light distribution. This in turn provides lighting designers with a flexible tool kit for presenting rooms in a professional and nuanced way with efficient visual comfort. The “ERCO individual” service also allows Bluetooth-capable variants of specific luminaires in the ERCO portfolio to be requested for the particular project.

LED Lighting

  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:

LED dimmers

  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.

A modifier

  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.

Flickering

  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.

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 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

  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.

Glare

  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.

If you want to share thoughts or feedback then please leave a comment below.

How is flicker created?

There can be various reasons for flicker. For manufacturers of control gear, ripple current is one which plays a major role. Ripple current is a proportion of alternating current that remains after rectification and the output filters. It is superimposed on the direct current and can have a different frequency and curve. This proportion of alternating current leads to power fluctuations at the LED module, which in turn create changes in luminance. The amount of superimposed alternating current and its frequency are deciding factors for the resulting flicker. The carrier technology used in the LED light source and the luminaire design also play a major role. If, for instance, phosphor is used as a converter material in LED light sources, this layer has a capacitive effect and will eliminate a small portion of the superimposed alternating current.

Individual perception

Depending on a person’s sensitivity and type of activity, flicker can be intrusive, distracting and can also affect a person’s well-being, even if luminance fluctuations are beyond the perceptible threshold (indirect perception). Here, peripheral vision often plays an important role, as it makes all movement seem more intense – no matter whether it is flicker or moving objects.

The extent to which flicker is perceived also depends on personal perception, and is connected to such things as vision, the irritability of the retina in the human eye, and the lighting conditions at the time. The majority of people are most sensitive at frequencies around 10 Hz, whereas most of the time they are no longer consciously aware of changes above 70 Hz. Nevertheless, people sensitive to light may experience problems such as fatigue and headaches, or there may be irritating stroboscopic effects at higher frequencies.

According to IEEE 1789-2015, there are now detailed descriptions on known flicker phenomena, their frequency of occurrence and their effect in various frequency ranges, and recommendations for driver design. Depending on whether flicker occurs in the perceptible range up to 70 Hz or the imperceptible range, different limit values apply. While as little as 0.5% of flicker can be perceived in the most sensitive range at around 10 Hz, flicker at 60 Hz needs to be at 60% to be perceived, in other words it needs to be 120 times stronger. Therefore, the limit values are considerably higher in this range.

High-quality drivers can reduce flicker considerably

Due to rectification of the mains voltage – 50 Hz in Europe – there is a high proportion of ripple current in LED Drivers at twice the mains frequency around 100 Hz. What’s more, compared to conventional light sources, LEDs immediately convert the operating current to light without the need for any major smoothing effects. To achieve operation that is as flicker-free as possible, a high-quality LED Driver and compatibility between the driver, dimmer and LED module are crucial.

The information in data sheets often provides an approach for rating control gear, for instance under “Output current ripple” or “Superimposed alternating current.” The values indicated usually refer to 100 Hz. The lower the values, the lower the risk of flicker.

Modern high-quality control gear such as Tridonic’s LED Drivers minimise ripple at the output and operate with perfectly matched components. High-quality components with clearly defined parameters, which are constantly checked in the lab are used.

The manufacturer particularly focuses on the critical frequency range around 10 Hz. Tridonic is looking to define new market standards here. Older generation devices with high ripple are now only recommended for applications that do not require persons to be permanently present.

Recommended dimming methods

While LEDs themselves carry no risk of flicker, dimming them, especially via pulse width modulation, can exacerbate flicker or even cause it in the first place. To avoid flicker, other dimming methods such as analog dimming are preferable. To compensate for the disadvantages of analog dimming at low dimming values, hybrid methods are becoming established.

Conclusion

Data on ripple currents in drivers provide a first indication of the risk of flicker. More reliable information for an informed decision can be obtained from data for the whole luminaire. Luminaire manufacturers can provide detailed information on the control gear used, the amount of superimposed alternating current, the dimming method and the frequency curves. Especially frequency curves between 0 and 120 Hz give an indication of how likely flicker is. The range between 10 and 70 Hz deserves special consideration – because in this range flicker has the greatest impact on well-being. What’s more, avoiding PWM dimming entirely will ensure largely flicker-free ambient conditions.

Stefano Rosa
Global Channels Director
Tridonic