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Introduction of LED lighting to offices--report on LED Next Stage 2012

[ 2013/8/23 ]

By Ken Okamoto (Lighting Designer) April 26, 2012 

For 4 days from March 6 to 9, 2012, "LED Next Stage 2012," which is an exhibition of LED lightings, was held at Tokyo Big Sight. This column reports on this exhibition. As described in the previous columns, LED lighting has been advanced quite rapidly. To be honest, it is so rapid that we, the workers in the lighting field, would become unable to keep up with the latest information when lowering our guards. It is not rare that the information about half a year ago is already old. In the previous exhibitions, many booths showed the advances that can be understood by everyone, such as the drastic improvement in brightness, but in the recent exhibitions, they show the improvements that cannot be grasped without some knowledge of lighting, such as the improvements in color rendering, beauty, smooth modulation, and glare-less lamps, etc. This is because the degree of completion of LED lighting has improved, and the required level for LED lighting has increased steeply. The lamps with sufficient brightness, color temperature, and color rendering are abundant in the venue, and so it is very difficult for most visitors to evaluate LED lamps. This tendency seemed strong at this LED Next Stage. However, this is not a big problem because the completion level of LED lighting has become higher. In other words, it is becoming okay to select any LED lamps.

This LED Next Stage included the program titled "the tour of the cutting-edge LED lighting" in which the experts in LED lighting (members of Japan LED Association) guide visitors to see many booths efficiently while grasping essential points. In the venue, I witnessed this tour many times, and saw each tour guiding a lot of visitors. It is recommendable to use this service, because you can deepen your understanding by walking around the venue while listening to the explanations by experts.

Since the entire lighting field started to shift to LED lighting, each lamp manufacturer has emphasized the exhibition of their products, and has escalated its scale. (For further report on the previous exhibition, please see the column.) It is not uncommon that a manufacturer holds a private event every six months or in a shorter cycle. Previously, most manufacturers conducted remarkable presentations at large exhibitions, such as Lighting Fair and LED Next Stage, but in recent years, manufacturers have more opportunities to release new products, and concentrate on their own private events. Probably because of this trend, Japanese lighting manufacturers looked less active at this LED Next Stage. Meanwhile, a remarkable number of overseas Asian manufacturers from China, Taiwan, and South Korea, etc. participated in this exhibition, displaying some high-quality LED lamps. I strongly sensed the vigor of overseas firms.

Like the report on Lighting Fair 2011 last year, let me enumerate some keywords that attracted my attention at this LED Next Stage 2012, as follows:

・Straight tube LED lamp
・Office lighting
・Color rendering
・Ceiling light
・Feeling of brightness
・Light guide plate
・Korean lighting products
・Other items that attracted my attention

I would like to report on the latest LED lighting related to each keyword.

Straight tube LED lamp

In the venue, straight tube LED lamps stood out. At the Lighting Fair last year, a straight tube LED lamp with the GX16t-5 bayonet cap satisfying the new standard (JEL801:2010) specified by Japan Electric Lamp Manufacturers Association was showcased, attracting significant attention as the energy-saving light source for office lighting. On the last day of Lighting Fair 2011, the Great East Japan Earthquake occurred. After the great earthquake, Japanese people became keenly aware of electricity saving, and the demand for energy-saving LED lamps is growing steeply. Especially, large offices, in which lighting accounts for 20-40% of electricity consumption, can reduce electricity consumption by saving the electricity for lighting. In this circumstance, the LED lighting for offices attracts attention. In offices, fluorescent lamps are adopted predominantly, and so the expectations toward straight tube LED lamps, which are an alternative to fluorescent lamps, are significant. The venue reflected such a social background, and many straight tube LED lamps that have been further advanced from the previous year were displayed.

・LEDZ TUBE of ENDO Lighting
The booth of ENDO Lighting exhibited the new "LEDZ TUBE" series of straight tube LED lamps, which were showcased at their own private event at the end of February.

Figure 1 Booth of ENDO Lighting

For the straight tube LED lamps of ENDO Lighting, original bayonet cap and socket were adopted in order to prevent the wrong insertion of conventional fluorescent lamps. The LEDZ TUBE series include various products, and the remarkably interesting product is Optical TUBE, which has narrower lighting angle than conventional fluorescent lamps and straight tube LED lamps. Conventional fluorescent lamps are characterized by diffusion light, which diffuses light to illuminate space homogeneously. Optical TUBE controls the diffusion of light with a special lens (1/2 lighting angle, about 50°). Its light source can be rotated by 25 degrees to adjust lighting direction while being attached to some object. This straight tube LED lamp can be used like a spotlight. The intensity of illumination under a lamp increases as lighting angle becomes narrower like ordinary light sources, and so the LED lamp can be attached to a high ceiling, to which straight tube fluorescent lamps are not suited. In addition to the attachment to a high ceiling, it is also possible to render the brightness in the vertical direction by adjusting the direction of illumination and focusing light on a wall like wall washers.

White TUBE, which diffuses light like conventional fluorescent lamps, has achieved 121 lm/w exceeding Hf fluorescent lamps, which are known as a highly efficient light source. Brightness is retained while reducing power consumption compared with conventional fluorescent lamps. For many years, fluorescent lamps are the strongest rival for LED lighting. Fluorescent lamps themselves can save some energy, so it has been difficult for LED to supersede fluorescent lamps. However, LED has advanced significantly.

Figures 2-4 The straight tube LED lamp of ENDO-Lighting LEDZ TUBE
From left, Optical TUBE, White TUBE, and conventional fluorescent lamps
A straight tube LED lamp can give sufficient brightness.

A straight tube LED lamp and its equipment set was priced at as high as about 20,000 yen for a single lamp of 40W and about 30,000 yen for two lamps, but its cost has been reduced to a realistic level, considering running cost, etc. In addition, some types have built-in power sources, while other types have waterproof straight tube LED lamps. We can expect that LED lamps will be further advanced.

・ECOLUX of Iris Ohyama
A wide array of straight tube LED lamps were exhibited at the booth of Iris Ohyama, which is becoming popular as a manufacturer of LED lamps because of TV commercials and the LED light bulbs sold at electronic retail stores. Its variety of products seems one of the largest among the manufacturers at this LED Next Stage.

Figures 5 and 6 Booth of Iris Ohyama bustling with many people

The LED products of Iris Ohyama have the brand name "ECOLUX." The product named ECOLUX HE is a straight tube LED lamp with an efficiency of as high as 100 lm/w. This is the most basic type alternative to fluorescent lamps in offices and large-scale stores, etc. ECOLUX HE includes the type that has a G13 bayonet cap like conventional fluorescent lamps and the type that has the new standard GX16t-5 bayonet cap called ECOLUX HE-L. As an attractive point, it is possible to choose ECOLUX HE for existing lighting equipment or ECOLUX HE-L for newly-built buildings.

There are other unique straight tube LED lamps, including ECOLUXθ, which has the angle-changeable concept like ENDO-Lighting's Optical TUBE, which can adjust lighting angle, ECOLUX SLIM, which has a tube diameter of 26.5 mm for the smooth renewal of Hf fluorescent lamps, and ECOLUX sensors, which can detect a person and brightness to adjust luminance. I was astonished by the product variety.

Figure 7 A wide array of straight tube LED lamps of Iris Ohyama

Figure 8 ECOLUX sensor mounted with sensors to detect a person and brightness

・110W straight tube LED lamp
Do you know extremely long 110W fluorescent lamps used in large space at stations and factories, etc.? Its length exceeds 2 m. Many booths showcased 110W straight tube LED lamps as an alternative to 110W fluorescent lamps. This lamp is so long that its maintenance requires more than one person and a lot of labor. In addition, 110W fluorescent lamps are installed mainly in the places where ambient light cannot reach and so lighting is necessary for a long time, such as subway stations, and so the merits of the shift from 110W fluorescent lamps to LED lighting are deemed to be considerable.

Figure 9 110W straight tube LED lamps of Iris Ohyama

Figure 10 Nichiei Intec exhibiting its products in an impressive manner
Figure 11 110W straight tube LED lamps of Mitsubishi Electric Osram

・In general
In general, straight tube LED lamps are becoming more affordable and more efficient. I felt that tube LED lamps will soon overwhelm fluorescent lamps in terms of initial cost in addition to power consumption and running cost.

Figure 12 Straight tube LED lamps of Panasonic Its price was changed from 16,000 yen to 12,000 yen.

Figure 13 Straight tube LED lamps of Toshiba Lighting & Technology
High-power straight tube LED lamp with the brightness comparable to Hf fluorescent lamp 32W

Office lighting

・Square base lights
Square base lights, which are square-shaped, are used mainly for office lighting like straight tube fluorescent lamps. In most cases, compact fluorescent lamps are used, and the common embedding hole size is 450×450 or 600×600. Most of the LED versions of square base lights have the size of the square base lights for conventional compact fluorescent lamps, considering renewal. Square base lights are often installed in offices like straight tube fluorescent lamps. The LED square base lights are attracting attention from the viewpoint of energy saving perspective in offices.

Figure 14 LED square base lights of ENDO-Lighting
A variety of square base lights are produced compared with other many lamp manufacturers.

Figure 15 LED square base lights of Daiko Electric

・Eco circadian lighting control
Panasonic not only showcased square base lights, but also proposed "eco circadian lighting control" for offices combined with control systems.

Figure 16 Panasonic's eco circadian lighting control 1

We, human beings, have the biological rhythm with a cycle of about 1 day (about 25 hours), and this is called circadian rhythm. During daytime working hours, we become active under the color temperature of about 5000K near to sunlight. During relaxing private hours after sunset, the color temperature of 2500-3000K is said to provide a calm atmosphere. Panasonic applied this circadian rhythm synchronized with the motion of the sun to lighting control, and proposed the idea of "eco circadian lighting control" to achieve a more comfortable office environment by controlling office illumination intensity and color temperature during daytime, evening, and nighttime.

Figures 17 and 18 Panasonic's eco circadian lighting control 2
Illumination intensity and color temperature are changed for daytime and nighttime. In daytime, lighting is white and has high illumination, and in nighttime, lighting has the electric bulb color and low illumination.

The lighting method in which color temperature and brightness are changed with time has been proposed by many lighting designers since before the distribution of LED lamps, but in the case of the conventional light source, the method of switching lighting with two kinds of light sources with different color temperatures was dominant. Therefore, there were some obstacles, such as the twofold initial cost for implements and the inefficient switch of color temperature. In the case of LED, the light source is extremely small, and so it is relatively easy to adopt two kinds of color temperatures in the implement and produce a color temperature-adjustable lamp, and light modulation and color temperature control can be conducted smoothly compared with fluorescent lamps. As LED lighting became popular, smooth unnoticeable lighting control became possible. In the near future, more offices will adjust color temperature and illumination intensity like eco circadian lighting control according to time and weather.

Color rendering property

Color rendering property, which is a weakness of LED, has been improved rapidly in recent years. Most of the latest LED lamps have a color rendering property of over Ra80, and the inorganic light unique to LED is now hardly seen in ordinary use. LED of over Ra90, which is used in museums and restaurants, etc. is not rare. For the latest LED lighting, the light that can make objects more beautiful is pursued. An example is the LED that not only has a high value of Ra, but also beautifies red objects. Average color rendering index Ra is evaluated based on how the color samples No.1 to No.8 can be seen (see Figure 19). Average color rendering index Ra is the index for rendering a space in which various objects exist homogeneously and naturally. There are other color samples for special color rendering index for judging whether the colors of a specific object can be illuminated beautifully and accurately. The color samples for special color rendering index include No.9 to No.15 (see Figure 19). Accordingly, there exists a lamp that has a high value of Ra and a low value of No.9 (red color). Accordingly, the high value of Ra does not mean that color rendering property is high for all objects.

Figure 19 Sheet of color samples for evaluating color rendering property

Focusing on this fact, some LED lamps are being developed under the concept of beautifying No.9 (red color) and No.15 (skin color of Japanese people) for special color rendering index.

・Bikoshoku (beautiful light color) LED of Panasonic
Panasonic showcased the product line titled "Bikoshoku LED" under the concept of making skin color more beautiful. Bikoshoku LED has a color rendering property of as high as Ra95, but is characterized by PS, which was developed by Panasonic by itself. PS stands for "Preference Index of Skin Color," which was developed by Panasonic to evaluate the preference of illuminated skin colors. The light with wavelength from 570 to 580 nm, under which skin dullness stands out, is controlled and adjusted to make the skin look beautiful. The PS value of Bikoshoku LED is 95.

Figure 20 Bikoshoku LED of Panasonic
The right photo shows a conventional LED, while the left photo shows Bikoshoku LED, which beautifies skin color.

Since Bikoshoku LED has high color rendering property, it not only beautifies skin color, but also can illuminate products in commercial facilities and foods at restaurants, etc.

・Artist module of Xicato JAPAN
The LED module of Xicato JAPAN (hereinafter called Xicato), which is renowned for homogeneous light, brightness, and beautiful coloration, is adopted as the light source for the products of various manufacturers. One of such LED products is Artist Module that has a color rendering property of over Ra95. This LED module is characterized by the function to make the red color look beautiful unlike conventional LED products.

Figure 21 Artist Module of Xicato
From left, a halogen lamp (Ra100), Xicato XSM Artist Module (Over Ra95), Xicato XSM80 series (Over Ra80), individual LED
Its light quality is comparable to that of a halogen lamp of Ra100.

The booth of Xicato demonstrated the measurement of average color rendering index (Ra) of Artist Module, by using a device for gauging average color rendering index.

Figure 22 Measurement of average color rendering index
The white button-like part of the meter is illuminated to gauge Ra value.

Figure 23 Results of the measurement of average color rendering index of Artist Module

The measurement result indicates that the average color rendering index of Artist Module is Ra99. The R9 value, which represents red color fidelity, was 91. Such direct display of measurements is very persuasive. (These measurements are not 100% correct because of the lighting of surrounding booths.)

This measurement device is the handy color rendering property gauge released by Konica Minolta Sensing. It can measure not only illumination intensity and color temperature, but also average color rendering index, which could not gauged easily before. I have often used the term "color rendering property" in the work of lighting design, but I have never seen the measurement of average color rendering index. This measurement device is compact and easy to carry around, and so it could be used for various purposes, including surveys and experiments. In addition, it would be useful for evaluating the quality of LED lighting, which varies considerably among products.

Figures 24 and 25 Handy color rendering property gauge of Konica Minolta Sensing

Ceiling lights
In the venue LED ceiling lights for houses stood out significantly like straight LED lamps and square base lights, especially the ceiling lights that are designed to be slim utilizing the characteristics of LED and that have the functions to adjust light and colors (color temperature conversion and color change) smoothly.

Figures 26 to 28 Ceiling lights of Panasonic
There are several lighting patterns, and it is possible to choose from general lighting, indirect lighting, and all-night light, etc. according to living scenes.

Figure 29 Light/color adjustable ceiling lights of Iris Ohyama

Figure 30 Color changeable LED ceiling light of Toshiba Lighting & Technology

This is rarely used for facilities, but the product lineup of each company indicates how much LED ceiling lights for houses and housing complexes are demanded.

Feeling of brightness

In lighting plans, the illumination intensity on the surfaces of floors and desks (illumination on horizontal planes) is emphasized as an indicator of the feeling of brightness, but even when the illumination on floor surfaces is low, by illuminating walls and ceilings, we can feel that the space is bright as a whole. This is called the feeling of brightness (feeling of brightness in space), and one of the most important keywords for lighting plans. The feeling of brightness can be improved by controlling the illumination on wall surfaces in the vertical direction and luminance, which influences brightness the most, as well as the illumination on two-dimensional floor surfaces. However, the feeling of brightness is sensuous and it has not been quantified like illumination intensity = Lux, and so it is very difficult to express the "feeling of brightness" in space in the planning stage to those who have no technical knowledge of lighting. This is a lingering problem pestering lighting designers.

・New indicator for the feeling of brightness of Toshiba Lighting & Technology
To cope with this problem, Panasonic proposed an indicator of the feeling of brightness in space called Feu several years ago. Feu quantifies the feeling of brightness in space based on the distribution of luminance inside the field of view. As the value of Feu is larger, the feeling of brightness in space is stronger. (For details, see the homepage about Feu of Panasonic:

In this LED Next Stage, Toshiba Lighting & Technology proposed "Weluna" for quantifying the feeling of brightness. Weluna quantifies the light reaching the eyes after being reflected from ceilings, walls, floors, or the like, (indirect illumination intensity at the height of the eyes) and is expressed in the unit Lux. Like Feu of Panasonic, the feeling of brightness is stronger as Weluna is larger. (For details, see the homepage about Weluna of Toshiba Lighting & Technology:

Figures 31 to 33 Demonstration of Weluna
Weluna is increased by illuminating the wall surface with downlights to increase vertical illuminance or illuminating the ceiling with indirect lighting. The demonstration of reducing power consumption while increasing Weluna would be persuasive.

From the academic perspective, the ideas for the two indicators are different, but I think that their purposes are similar to each other. When there is more than one indicator for the feeling of brightness in the same lighting field, I wonder which should be used. Accordingly, I hope that the indicators for the feeling of brightness will be unified and it will be diffused in the field of lighting design. With a tool for quantifying the feeling of brightness in space, such as Feu and Weluna, the scope of lighting design would be broadened considerably.

Light guide plates

In the sign display field, LED-attached light guide plates became popular. The light guide plates that glow with the LED light from the small holes of acrylic or glass parts do not require a lot of fluorescent lamps behind the sign like conventional ones, and so they are characteristically slim.
As LED lighting became highly efficient, the devices mounted with light guide plates are increasing in the field of general lighting. In the venue, I saw many products of light guide plates compared with previous exhibitions.

Figures 34 to 36 "LIGHT PANEL BASE LIGHT" of KOIZUMI Lighting Technology
"LIGHT PANEL BASE LIGHT" developed based on the collaboration between KOIZUMI Lighting Technology and Sumitomo Chemical. The panel glows so uniformly that we doubt that this lighting is the light guide plate type, and light intensity is sufficient for a lighting apparatus. The pendant and recessed types are produced.

Figures 37 and 38 Light guide plate downlight "LUXELA" of Kowa
Lightweight and thin compared with ordinary downlights.

Figure 39 Light guide plate-type bracket of Kowa
Product developed by utilizing the characteristics of light guide plates and LED lighting

Figure 40 Light guide plate-type square base light of Kowa
Kowa produces a variety of devices mounted with light guide plates.

Figures 41 and 42 Light guide plate downlights of YOSHINICHI
Light guide plate downlight with a thickness of 11.5 mm.

Figures 43 and 44 Proposal for the attachment of a light guide plate to an inspection door
The booth of Yoshinichi gave a unique proposal for setting a light guide plate on an inspection door.

As LED became highly efficient, light guide plates are being used for lighting devices in various ways. The surface emitting property seems to be utilized for inventing new lighting apparatuses. Organic EL, which attracts attention as the next generation lighting after LED, has similar characteristics to light guide plates, and some organic EL products can be bended like a sheet of paper. In the near future, light will also be handled like building materials, such as glass and wallpaper, rather than merely being emitted from lighting devices.

South Korean lamp manufacturers

As mentioned at the beginning of this column, I keenly felt the vigor of Asian lamp manufacturers at this LED Next Stage.
The manufacturer ALTO was the most impressive. ALTO showcased mainly LED glare-less downlights.

Figure 45 Booth of the South Korean manufacturer ALTO

Figures 46 and 47 Wall washer (left) and adjustable downlight (right) of ALTO

Not only base downlights but also adjustable downlights and wall washers, which are still scarce in Japan, are available. In addition, there are a broad range of sizes for downlights--embedding hole diameter: φ55mm, φ85mm, φ100mm, φ125mm, and φ155mm.

Figure 48 Small-sized LED glare-less downlight (ALTO)

With a Wi-Fi-compatible power source, light can be adjusted by using iPad, iPhone, or Android. (Ordinary light adjustment is compatible with PWM and DALI.)

Figure 49 Light adjustment with iPad (ALTO)

Glare-less downlights were used for the booth. These seemed comparable to Japanese products. I look forward to seeing their future expansion.

Figure 50 Glare-less downlight set at the ceiling of the booth

I was also attracted by the South Korean manufacturer FEELUX, which may be known for indirect lighting, etc. to the staff in charge of overseas projects. There are a wide array of LED line lamps specialized in indirect lighting, and so size and color temperature can be selected according to purposes. Because this manufacturer has produced the fluorescent lamp type products for indirect lighting since before the advent of LED, its LED products are retained high-quality among a lot of similar products of LED line lighting.

Figure 51 LED line lamps of FEELUX

Other noteworthy items

Let me introduce other items that attracted me in the venue.

Figures 52 and 53 LED light engine downlight of Toshiba Lighting & Technology
Downlight developed under the concept of replacing LED units in the same way as lamps.

Figures 54 and 55 Lineup of replaceable LED units and downlights (Toshiba Lighting & Technology)
For replaceable units, brightness, light distribution, and color temperature, etc. can be selected. A total of 44 kinds of LED units are available.

Figures 57 and 58 Outdoor LED units with the same concept (Toshiba Lighting & Technology)
These can be used for brackets, bollards, and downlights under eaves, etc.

Figure 59 COB-type LED downlight released from Daiko Electric

Figure 60 Affordable LED downlights for houses of Daiko Electric
LED downlight compatible with heat insulating buildings priced from as low as 6,800 yen

Figures 61 and 62 Xicato's new small-sized LED module and small-diameter reflector for this module
As a smaller module debuted, lighting apparatuses will get smaller.

Figures 63 and 64 LED wall washer downlight of Maxray

Figures 65 and 66 Small-sized LED floodlight of Iwasaki Electric "LEDioc FLOOD NEO"
Lightweight and compact compared with its old models. The products with 110w, 80w, 60w, and 40w are available, and it is possible to select from medium angle, wide angle, and super optical angle. They seem useful for lighting up an object. (the same sizes for 110w and 80w and for 60w and 40w)

Figures 67 and 68 There are an increasing number of LED bulbs that distribute light widely and LED bulbs that emit light upward like incandescent lamps
(Left: Toshiba Lighting & Technology, Right: Mitsubishi Osram) Products with a luminous flux of 800 lm and 1000 ml have been developed.


As described in the previous columns, the field of LED downlights, which are mainly used in houses and commercial facilities, are being matured as brightness and light quality have been improved. The next rival of LED is fluorescent lamps. Amid the electricity saving trend that began last year, the LED lighting for offices is growing rapidly. At this LED Next Stage, straight tube LED lamps and LED square base lights for offices stood out significantly. I was also surprised by the improvement in LED lighting for offices. Until last year, I could say with confidence that fluorescent lamps are superior to LED comprehensively considering brightness, prices, and efficiency, etc. although fluorescent lamps are inferior to LED in product life, but I felt that this relation is being reversed gradually. The full-scale shift to LED in offices is approaching. However, it was pointed out through the power saving trend that conventional lighting was too bright. I think the next generation energy saving office should be aimed at developing energy-saving comfortable office space by adopting the task-ambient method introduced in the previous column rather than pursuing the same level of brightness while merely replacing apparatuses.

Recently, I often witness the passionate activities of South Korean manufacturers in various fields, and I was astonished by the quality of their lighting products. It can be said that Japanese lamps are high-quality and world-class, but I expect that the quality of LED lighting in the entire Japan will be improved in consequence of growing imports of high-quality LED lighting products from other Asian countries and fierce competition.

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