BETSUISimply stated, electrical energy can be converted to light more easily in LEDs than in incandescent lamps or fluorescent lamps.
The biggest selling point of this kind of lighting is the reduced power consumption. Cost is also among the reasons why LED ceiling lights are very popular. The lights are priced fairly compared to other similar lights. For starters, most 6W LED light bulbs have high lumen ratings that could provide the same light output as a 60-watt incandescent light bulb. Also, a well-designed LED circuit could result to energy efficiency ratings of as high as 80%, which means than 80% of the energy used is converted to light energy and only a small percentage is lost as heat energy. On the other hand, some incandescent bulbs operate at only 20% efficiency. This means that LED light bulbs could produce sufficient light without consuming as much energy as most traditional lighting fixtures. There is also minimal heat dissipation, which also reduces air conditioning costs.It is however important to note that there are some types of LED ceiling lights that are expensive. Their quality and durability however justifies the cost.
Publication: January 8, 2015 Professional affiliation and official position are at the time of publication.
MURATAThat’s right. We are very pleased, as receiving the Prize means that our research results were recognized. The LED ceiling light for fiscal 2013 achieved high energy-saving performance—the maximum luminous flux within the scope of the benchmark for that for the applicable room size (number of tatami mats)* and the intrinsic energy consumption efficiency of 102.4 – 104.8 lm/W (lumen/watts). We believe that one of the reasons we received the Prize is because we relentlessly pursued the theme of decreasing optical loss to successfully achieve both brightness and energy efficiency.
Inside an LED ceiling light are rows of LEDs, which total about 320 in lighting for a 14 tatami mat (23 m2) room. As LEDs pose the danger of causing burns or electrical shock when directly touched with hands, each individual LED is overlaid with a dome-shaped cover.
MURATAI believe that highly energy-efficient lighting using LEDs will become popular in other countries as well, not only limited to Japan. It is a big wish, but my hope is that our products will help spread an eco-friendly mindset regarding lighting among people around the world.
As mentioned above, LED ceiling lights can be installed anywhere you can imagine. The main aim of using LED ceiling lights is saving energy thus the natural lights/bulbs can be replaced with LED lights anywhere you wish to reduce lighting costs i.e. your home; kitchen ceiling, bathroom e.t.c. You can also put LED lights in your office. The lights simply reduce energy costs and add style around your home, office or facility.
Take fluorescent lamps, one of the conventional light sources, for example. They are pipe-shaped and the surface of the tube emits light so that light diffuses in various directions. As for LEDs, the area that emits light is small and its light only emits straight ahead. This is what is meant by the different light distribution.
The layout of LEDs varies depending on the lighting equipment. LED lighting equipment uses a different number of LEDs depending on the product lineups for various sizes of rooms. We relentlessly pursued finding the optimum lens layout for each size of lighting so that the entire shade illuminates beautifully regardless the number of LEDs.
Very many people prefer LED ceiling lights because they are usually located far away from interference. The location i.e. on ceilings helps to avoid unnecessary accidents because people can’t reach them to cause fatal interference. Also, people prefer LED ceiling lights because they offer better light distribution because of their location. Most wall lights or lamp stand lights offer poor light distribution with variations depending on the angle/s of light beams.
Light Emitting Diode or LED is a new lighting technology which has become very popular today as people look for ways of cutting down emissions and energy costs. There are very many types of LED light bulbs however the most common type of LED light bulbs are LED ceiling lights.
Since the development of this technology, LED light fixtures have been deemed as the future of lighting – and LED ceiling lights are no exception. The current design and features of these fixtures are ideal for indoor lighting needs, which is why they are slowly replacing traditional light bulbs that are currently in use.
LED lights are now widely used for residential lighting, as well as commercial applications such as in offices, conference rooms, warehouses, factories, schools, airports, hospitals and hotels.
It is extremely difficult to discern the cause of the failure—whether it is because the simulation is wrong, or the method to produce the prototypes are to blame. We occasionally investigated the simulations retroactively to check if a certain optical performance was the result of the dislocation of the prototype shape in a certain manner that we had supposed.
As the name suggests, LED ceiling lights are usually fixed on building ceilings. LED ceiling lights come in a variety of shapes, designs and sizes however they serve the same purpose. Installing the LED ceiling lights is simple and doesn’t require specialization. A light emitting diode is a point-like luminous body, which means that lighting fixture designers have virtually complete freedom when it comes to design. LEDs can be easily adapted for use with a variety of power supplies and casing as well. In fact, today’s LED ceiling lights are available in a range of styles, from sleek round and square panel lights and intricate chandeliers to pendant lights that come in various shapes such as cones and cylinders. They could be used for ambient lighting and fitted with high efficiency drivers and dimmers to easily alter the atmosphere of a room.
Achieving Both Brightness and Energy Savings with Development of LED Ceiling Lights that Widely Disperse Light
MURATAInitially, LED lighting attracted attention due to being highly praised for being “energy efficient.” However, the biggest reason behind the increased popularity is probably due to the drop in the price of LEDs. In the earlier days when LEDs first appeared in the market as lighting, they were thought to be too expensive to replace incandescent bulbs and fluorescent lamps even though they were energy efficient. But their prices decreased in line with the increase in their popularity. Now, they have become a light source used in daily life.
Along with the spread of the energy saving mindset, LED lighting for home use has become popular. The general perception is that LEDs illuminate brighter while consuming less power. However, depending on the type of lighting equipment, the corners of rooms may seem darker when using LED light. This is attributable to the nature of LED light which shines in a straight direction without diffusing out.
Were there also many innovations to the layouts of the lenses?
BETSUIHitachi recently entered the LED lighting field in 2011, and I myself got involved in LED lighting for the first time in 2012. So we started the development without any real experience.
Enhanced awareness of energy savings and acceptance of LED lighting
More recently, LEDs are being used in panels with irregular shapes using light-guiding plates or in turning signal lights of cars with excellent designs. Conventional lighting has been classified as “bulb-type” and “halogen-type,” etc. and it would be great if there would be a lighting classification unique to LEDs… I believe that there are still many possibilities yet to be explored for LED lighting.
However, I think that there should be exclusive lighting equipment for LEDs. Since existing lighting equipment is formed to use tubes or bulbs, the scope of application are limited. In contrast, LEDs are so small that they can emit light anywhere. It might be interesting to have “lighting equipment that can be realized only with LEDs” by taking advantage of this feature.
First, the “subdued” light is too omnidirectional and lacks intensity in the horizontal direction. Moreover, some parts of the light bounce back from the fine irregularities of the rough and abraded section and return in the direction of the LED light, resulting in their being absorbed and wasted. That’s why we worked on development focusing on a lens with a “glossy,” smooth surface.
MURATAAn LED ceiling light does not have any LEDs in the central or periphery areas. However, we wanted such sections to be solidly illuminated. Therefore, in order to have them illuminate more effectively, we prepared two types of lenses and arranged their layout so that their respective characteristics can be realized.
For example, the filament of an incandescent lamp at a high temperature emits electromagnetic waves of various wavelengths including infrared rays, and the portion of energy that is not converted to light is wasted. In this regard, LEDs have an energy width called band gap that matches the wavelengths of lights, so that the majority of electric energy is converted to light. This means that LEDs have higher energy-to-light conversion efficiency. In other words, they are energy efficient.
MURATAThe optical lens which we developed bends a light at a horizontal angle of 75 degrees. By adopting this optical lens to the dome-shaped cover, light of the lateral direction becomes stronger than light of the front direction.
The performance of LEDs is also improving, and researchers and engineers like ourselves that utilize LEDs in technologies and products are devoted to research that will provide people around the world with better lighting environments. In my work, I want to be of some help in addressing the energy issue, always striving to offer products of greater value to society.
MURATARated power consumption is one of the benchmarks used for comparing energy efficiency of lighting. For products applied to rooms of the same size measured in number of tatami mats, lower power consumption means higher energy efficiency, or energy savings. As far as Hitachi’s products are concerned, the LED ceiling light released in fiscal 2013 for a room of a size up to 14 tatami mats (23 m2) consumes approximately half the power of an energy-efficient-type fluorescent light. Moreover, with the continuing advances in LED ceiling lights every year, an approximately 18% reduction in power consumption is even being realized compared with LED products of the previous fiscal year.
LED Ceiling Lights LED Downlights LED Panel Lights T8 LED Tubes T5 LED Tubes Parabolic Troffers LED Track Lights LED Recessed Lights Lensed Troffers COB LED Bulbs
BETSUITo make things more complicated, there are cases in which simulations produce correct results but the actual products do not emit light correctly because of the differences in production methods. Prototypes are created by cutting plastic, but actual products are created by pouring melted plastic into molds (injection mold process) so that mass-production is possible. Since there are these differences in the production methods between prototype and actual product lenses, we must also take into account the possibility that “since it is a prototype, it may not emit light as expected.”
However, lighting is a world of “vagueness.” Once we establish numerical targets and created lighting equipment that achieves them. When we are sure of the results, we seek confirmation from the people in the business operations division that requested the development. Then, we usually receive such comments as “we want the light to be a little more fluffy” and “can you have this area illuminate more beautifully?” And we wonder, what do “fluffy” and “beautifully” mean? We cannot set up quantitative targets. It is difficult, but also quite intriguing.
Achieving even higher efficiency by optimizing the lens layouts
BETSUII hear that the product is selling well. It is only three years since Hitachi entered this market, but the Company is demonstrating its presence despite being a late comer. At the lighting sales sections of home appliance mass retailers, our products are now displayed in one of the most visible places. What really pleases me is that customers thinking about purchasing LED lighting visit the sales floors and select Hitachi’s products after confirming how they illuminate.
BETSUICurrently, LED lighting is mainly used as an alternative for incandescent lamps, fluorescent lamps, halogen lamps and other lighting sources. Therefore, in most cases, LEDs are set to reproduce the illumination of existing lighting equipment.
Why is it that we are seeing more LED lighting in our daily life than before?
After starting the development I realized that in the field of optics, lighting poses unique difficulties. Before getting involved in LED lighting, I was engaged in plasma display research and Mr. Murata was involved in backlight research for projectors and liquid crystal display (LCD) TVs. Development of such technologies allowed us to set quantitative targets. In the case of the backlights for LCD TVs, for example, stringent designing is possible and effectiveness can be clearly judged by setting numerical targets for having them illuminate evenly.
The covered LED as a whole is called an “LED unit,” and Hitachi has added a lens function to the dome-shaped cover of each unit.
BETSUISome other products also have modified the covers so that light diffuses out. A generally employed method is to make the surface of the cover “rough and abraded,” like ground glass, to soften the emitted light. By doing so, a “subdued” light is diffused. This apparently solves the problem of LED light only emitting straight. However, this method is not a very efficient way to diffuse light.
* Based on the “Standards for Indication of Applicable Room Size by Number of Tatami Mats in Catalogue for Housing” (Guide 121:2011) defined by Japan Lighting Manufacturers Association (JLMA).
MURATADevelopment of a lens starts with determining its shape by conducting simulations. We then produce a prototype and test it for verification. However, it is hard to obtain the expected results.
Do you think the acceptance of LED lighting will expand at an even more accelerated pace?
BETSUIIndeed. A lens with a smooth surface can easily bend light, but the bent light may become too intense in some parts. When this happens, it causes bands and patterns of light to appear on the outer cover (“shade”) of the lighting equipment. To avoid this, we had to work intensively on designing the lens.
I hear the fiscal 2013 product receive the Energy Conservation Grand Prize in Japan.
Of the two types, one is a lens to brighten the central part of the lighting equipment and the other one is a lens to brighten the periphery section. We successfully developed an LED ceiling light that illuminates the entire shade brightly by optimally laying out these lenses.
BETSUIHave you ever looked at the inside of a home-use LED ceiling light?
Figure 2: Types of LED unit covers and the way light diffuses out
Figure 3: Comparison of difference in LED lighting illumination of LED
Enhanced awareness of energy savings and acceptance of LED lighting Hitachi’s original “domed LED units” with lens function Starting with no experience or knowledge Achieving even higher efficiency by optimizing the lens layouts Future potential of LED lighting
LED is a high intensity light source due to the electroluminescence effect, which occurs when electrons react and move through the semiconductor material. When switched on, LED ceiling lights would start immediately; there would be no flickering and distracting humming. Most LED lamps, specifically panel lights, feature PMMA or PC acrylic sheets that create uniform lighting. They also come with diffusers to create a soft and comfortable glow. LED lights, particularly panel lighting systems, typically feature a lightweight aluminum frame. However, they could also come with a variety of sleek chrome and classic nickel finishes, as well as cased-glass shades coated with other types of optical material such as opal glass to evenly distribute high-quality illumination.
Therefore, if fluorescent lamps are replaced by LED lighting without any special modifications, the brightness will seem odd. This is because the nature of LEDs causes the problem that only the part directly below the lighting is unusually bright while little light reaches the walls of the room. This was the issue that needed to be solved with LED lighting.
Figure 1: Comparison of power consumption (lighting applicable up to 14 tatami mat (23 m2) rooms)
Can LEDs replace conventional light sources without being modified?
The issue has been successfully addressed by the “domed LED units” with lens function, originally developed by Hitachi.
MURATANo, they can’t. Since LEDs and conventional light sources have different light distribution, people may feel that they have different illumination with just a simple replacement.
BETSUIAnother major reason is that people have become more conscious of energy savings since the large-scale blackouts following the Great East Japan Earthquake. Conventional lighting is progressively being replaced by LED lighting, as the latter’s energy efficiency is now widely understood.
The LED ceiling light developed by Hitachi achieves both brightness and energy savings. It uses a lens to disperse the light out so that the entire room is lit brightly. This article casts a spotlight on the development of LED ceiling lights, which have been continuously evolving.
It is important to note that the lights are suitable for tight spaces. If you don’t have a lot of ceiling space to put chandeliers, it is advisable to install LED ceiling lights because they require very little space for installation. The lights have a special variety i.e. the low heat LED ceiling lights (recessed) which produce very little light thus are ideal for tight spaces.