Microplasma Planar Lighting-By Eden Park Illumination

Copyright 2012 Eden Park Illumination

903 North Country Fair Drive Champaign, IL, USA

61821

[email protected] www.edenpark.com

Microplasma Planar Lighting Flat ‐ Thin ‐ Light Weight ‐ High Quality Light

Advantages

A True Planar Technology 50,000 Hour Product Life

5 Millimeters Thick High Quality Light

Instant On/Off No Reflectors No Heat Sink No Diffusers No Mercury

By Cy Herring, VP Research, Jeff Bulson VP Development and Marty Dugan, VP Product Management

Microplasma Planar Lighting ‐ Copyright 2012 Eden Park Illumination |Page 2 of 11

Table of Contents

Advantages ............................................................................................................................................................ 1

Introduction ........................................................................................................................................................... 3

The Problem with Fluorescent Lamps: Mercury ................................................................................................ 3

The Solution: Microplasma Flat Panel Lamps ................................................................................................... 4

Microplasma Lighting Technology ...................................................................................................................... 5

Microplasma Lamp Structure .............................................................................................................................. 6

Lamp Seal and Phosphors ................................................................................................................................... 6

Advantages of Microplasma Technology ........................................................................................................... 7

OLED Limitations .................................................................................................................................................. 8

Cost Advantages of Microplasma Planar Lamps .............................................................................................. 8

Advanced Microplasma Lamp Applications ....................................................................................................... 9

Summary ................................................................................................................................................................ 9

Appendix .............................................................................................................................................................. 10

Typical Specifications for a Microplasma Lamp .............................................................................................. 10

Glossary ............................................................................................................................................................... 11

Eden Park Illumination’s Microplasma Lamp


Microplasma Planar Lighting Technology Eden Park Illumination, Inc.

Introduction

Microplasma lighting is a patented gas discharge lighting technology that Eden Park Illumination has developed for current specialty lighting and future general lighting applications. The lamps emit a warm high quality light and do not require high cost manufacturing processes (i.e. clean rooms, semiconductor fabrication), to produce which enable low production and materials costs. The lamps contain no mercury or other environmental toxins, are less that 5mm thick and are estimated to last for over 50,000 hours (about 10 years of average use). It is a true planar lamp, which emits all of its light directly from the surface of the lamp and requires no additional technology such as diffusers, reflectors, or heat sinks. This microplasma flat panel lamp technology is ideal for applications where flat, thin, high quality and environmentally responsible lighting is needed. This paper covers the specifications of the patented core technologies involved as well as applications and future consideration for the technology.

The Problem with Fluorescent Lamps: Mercury

Gas discharge lighting technologies in the form of fluorescent lamps have dominated the lighting market because they are both efficient at producing light and inexpensive to manufacture. Although their efficiency and low‐cost have made them the main‐stream lighting technology, they have several drawbacks that are of increasing concern for many users. The highest efficiency lamps have poor lighting quality that limits their use to outdoor applications and, in general, arc‐lamps are so bright that they can only be used in warehouse type applications. However, the two biggest concerns with gas discharge lamps are the use of toxic mercury in construction, and their limited lifetime. Environmental concerns are placing more stringent regulations on


disposal of mercury‐containing products, often making recycling mandatory and at a higher cost than the original purchase price of the lamp. Other areas of concern are poor instant‐on capabilities, dimming, and warm‐up time. New emerging technologies have been on the horizon for the past decade, such as LEDs and OLEDs, promising low‐cost and high‐efficiency lighting solutions to eventually replace mercury‐containing lamps and low CRI arc lamps. Time has shown that OLEDs are not a legitimate candidate for lamp replacement technology due to their high‐costs, low lumen output, and limited lifetime ‐ at least for the next decade or two. LED technology has shown great strides with efficacy gains, but at high costs and with performance falling short of expectations. The greatest problems with commercial LED technologies is the poor lighting quality, high costs, and the fact that many of the products do not live up to their stated specifications (Ref: US DOE CALiPER Program reports). Lifetime and changing light quality over time are also a major concern for the technology. Despite these limitations, LED lighting remains a promising technology for general lighting. But there remain some specifications that LEDs do not meet well. It may be that LED and other technologies, including microplasma lighting, work in combination in the future to deliver a wider and more cost effective set of lighting solutions to the general lighting industry.

The Solution: Microplasma Flat Panel Lamps

Eden Park has developed an inexpensive method of manufacturing flat glass lamps with exceptional lighting quality that does not require the use of mercury or other toxic materials. The lamps are inexpensive when compared with other high quality flat lighting devices because they are constructed from inexpensive materials with a simple fabrication technique. The light quality comes from an internally‐developed custom blend of phosphors which can be tailored for individual applications. The construction allows flexibility in lamp shape, contour, and color. The lamp works by generating ultraviolet (UV) light using a mercury‐free gas discharge in an inert xenon gas. The UV light shines on a phosphor coating inside the lamp, producing visible light in a similar manner to fluorescent lamps. Although the xenon gas is not as efficient as mercury for lighting applications, the planar form‐factor allows a higher percentage of the light to be utilized in real‐world applications than standard fluorescent lamps. This is because standard fluorescent lamps must be enclosed in a reflective luminaire which absorbs as much as 20% of the lamp output. The Eden Park flat form factor combined with our new microdischarge technology make the lamp efficacy competitive with compact fluorescent lamps today but without the mercury.


Microplasma Lighting Technology

The patented lighting technology was developed and patented at the University of Illinois and works by confining the gas discharge inside the lamp into thousands of tiny cavities formed into the glass. This confinement allows the lamp to operate at higher pressures than conventional cold discharges which enables greater efficiencies to be achieved when compared to lower pressure xenon discharge lamps. Inside a running lamp, xenon atoms in the discharge form molecules called diatomic xenon which emit UV radiation that is converted to white light by the phosphor coating inside of the lamp. The efficiency of the lamp depends on the ability to generate the diatomic xenon; this process is helped with increasing pressure since there are more xenon atoms per volume that can interact. However, typical discharges form arcs or streamers at higher pressures due to the low thermal conductivity of the xenon gas. The key point is that microdischarge technology allows the lamp to operate at higher pressures in a stable manner, thereby achieving higher efficiency of UV production. Figure 1 shows a cross‐section of the glass envelope making up the lamp structure. The microcavities are etched into the glass before the application of phosphor and before the lamp is assembled.

Figure 1. Cross‐sectional view of a flat panel lamp showing microcavities inside the glass envelope. An additional benefit to the structure shown in Figure 1 is that the electrodes supplying power to the lamp are outside of the gas discharge region. The lamp in this configuration works as a dielectric barrier discharge device which results in projected lifetimes of >50,000 hours. Keeping the electrodes away from the gas discharge prevents metal sputtering which is the major contributor to the limited lifetime of standard fluorescent lamps, arc lamps (street lamps, high‐bay lamps, etc.), compact fluorescent lamps, metal halide lamps, and tungsten filament lamps (which erode through electrode evaporation).


The xenon gas inside the lamp remains in the gas phase to temperatures of less than ‐162 °F, so there is no warm‐up time as with mercury‐containing fluorescent lamps where the lamp needs time to generate heat to evaporate the liquid mercury inside the lamp to achieve full brightness. Inside the lamp, the gas pressure is ≤500 Torr so the lamp will function normally to >10,000 feet elevation without any change in performance. Eden Park’s lamps are instant on/off, bright, dimmable, require no warm‐up time, operate over a wide range of temperatures (from 0 °F to 200 °F), and use no toxic materials in construction, including mercury.

Microplasma Lamp Structure

As shown in Figure 1, the lamp is composed of four layers of glass, each layer being 0.043” thick and may or may not be strengthened glass; if strengthened, it is similar to Corning® Gorilla® Glass used in modern phones. When combined with the gas discharge layer and electrodes, the total thickness is <0.25”. Since the glass itself serves as the mechanical structure of the lamp, there is no need for additional external structures for support or power delivery, so the lamp can maintain the ¼” thickness even for lighting tile areas of many square feet. The shape of the lamp is not important to the function as long as the discharge gap remains constant, so the lamp can be made in different shapes, from cylindrical to spherical, and cut into any desired pattern such as formed letters for signage. For these special shapes, the glass would be prepared before assembly by heating and shaping, then cut to the desired pattern, and the remaining processes, including lamp assembly, seal, and back‐fill, would be performed in a similar manner to the standard flat lamp. The discharge gap spacing is determined by using spacers strategically positioned throughout the lamp structure. This forms a grid pattern that can be seen on close inspection of the front of the lamp.

Lamp Seal and Phosphors

Lead‐free glass frit forms a hermetic seal around the perimeter of the lamp trapping the xenon gas inside the lamp with a technology that can maintain the seal for >100 years. This seal contributes to the longevity of the lamp ensuring that no gas leaks into or out of the lamp, which would limit the lifetime. The robust seal and external electrodes both enhance lamp lifetime, leaving one component which ages over time: the phosphor. Eden Park uses high‐quality phosphors developed for the plasma TV industry. These phosphors have projected lifetimes of >50,000 hours for 70% brightness (using the IES LM‐80 testing protocol). The lamp will continue to operate after 50,000 hours, but not be as bright as it was before aging. Also, the phosphors are mixed from red, green, and blue components giving the ability to precisely control both the color point and the color temperature. This process produces a typical CRI of>80. Phosphors are screen‐printed onto the inside glass envelope before lamp assembly. Since they are screen‐printed using standard practices, text, shapes, and colors can be printed onto the


glass in the same way a colorful pattern is screen printed onto a T‐shirt. In this case, multiple screens would be prepared for each phosphor color mix and used sequentially to build up a color image which could be a simple border around the perimeter of a lamp, a company logo, or detailed graphics.

Advantages of Microplasma Technology

The overwhelmingly positive reaction to microplasma lamps has centered on the visual quality and appearance of the light and lamp. The appearance of the light, which has a unique, warm glow, and very uniform diffuse luminance, has intrigued those who have seen it. This truly planar light is inspiring designers and working its way into flat panel designs where thinness is a key requirement or design element. And the thin profile goes beyond just design trends. Due to the thin dimensions, low weight, and the lack of the need for reflectors, diffusers, or heat‐sink‐assistive technologies in the fixturing, the lamps can be packaged, shipped, and stored in lower profile boxes. This advantage greatly reduces packaging, shipping, and warehousing costs. Also, its long product life and mercury‐free, low environmental impact, round out a much needed set of specifications that focuses on sustainability. Advantages of Microplasma Planar Lamp Technology: Green Technology ‐ Mercury‐free and lead‐free (contains no toxic materials), recyclable,

and environmentally friendly Ultra thin (less than 5mm) and light weight Eliminates the need for external reflectors to control the light distribution Offers long life of up to 50,000 hours Generates less heat – No heat sinks required Flat cleanable surface Instant on/off Microplasma lamps have several distinct advantages over OLED and LED lighting technologies as shown in the chart below.

Technology

Thickness (mm)

Heat sink required

Reflector/ Diffuser required

Luminance(cd/m2)

CRI Lifetime (hours) @70%

Efficacy (lm/W)

Microplasma 5 No No 8000 80 ‐ 85 50,000 Currently 30 – 40 *

OLED 2 No No 1000 80 10‐15,000

60

LED 20 Yes Yes 3000 80 ‐ 87 50,000 85

Comparison of Lighting Technologies Specifically for Planar Lighting Form Factors. (See appendix for full specifications for a typical microplasma planar lamp) *Note on efficacy levels ‐ Microplasma lighting is a relatively new lighting technology compared to LED and OLED. Several breakthroughs have been achieved over the last three years that


have boosted efficacy. Current efficacy specifications are 30 – 40 lm/W as of 2011. This level is double the highest rating from 2010. Efficacy is expected to grow to over 60 lm/W with theoretical maximums well over 100 lm/W.

OLED Limitations

OLED Product Lifetime ‐ The biggest technical problem for OLEDs is the limited lifetime of the organic materials. In particular, blue OLEDs historically have had a lifetime of around 14,000 hours to half original brightness (five years at 8 hours a day). OLED High Manufacturing Expense ‐ OLED manufacture currently requires process steps that make it extremely expensive. Specifically, the use of Low‐Temperature Polysilicon (LTPS) backplanes is required; LTPS backplanes in turn require laser annealing to form an amorphous silicon substrate, so this part of the manufacturing process for AMOLEDs starts with the process costs of standard LCD, and then adds an expensive, time‐consuming process that cannot currently be used on large‐area glass substrates.

Cost Advantages of Microplasma Planar Lamps

Microplasma lamps have a low cost of manufacture compared to LED and OLED technologies. No clean room or semiconductor processes are required. Materials are common glass, phosphor, and noble gas components. Manufacturing processes are standard screen printing, mechanical assembly, oven seal, and vacuum/gas fill processes. Therefore, the cost per lamp at volume production levels enables costs to be much lower than LED and OLED final fixture products. More importantly, unlike LED lamps where cost scales rapidly with lamp area, the cost of a microplasma planar lamp scales at a rate lower than LED lamps. Therefore, product costs become very competitive as microplasma lamps get bigger.

Market Price Comparison of Fixtured Planar Lighting Products (Typical high quality 12 Inch x 12 Inch Panel lamp)

Microplasma OLED (paneled) LED

Purchase price $100 ‐ $200 $1000 ‐ $5000 $200 ‐ $400

Electricity usage 100 W 25 W 25 W

Luminous flux 3000 lm 1500 lm 2500 lm

Efficacy 30 lm/W 60 lm/W 85 lm/W

Lifespan 50,000 h 8,000 h 50,000 h

Lamp cost over 10 years $100 $2000 ‐ $10,000 $200

Comparison based on 8 hours use per day – Lifetime at %70 luminous flux

(See appendix for full specifications for a typical microplasma planar lamp.)


Advanced Microplasma Lamp Applications

Ultraviolet Applications Inside the lamp, the xenon gas produces UV radiation at 173nm. If the phosphors are not used in lamp construction, and a UV grade glass is used, the lamp becomes an ultraviolet lamp. Eden Park has fabricated UV lamps in this manner, with applications in water purification, surface activation treatments, and photodynamic therapy. The UV applications are not limited to 173nm radiation, as a phosphor can be used to convert this wavelength to other areas of interest including 173‐ 220nm, 260nm, or any wavelength in the UVA, UVB, or UVC region. When used in this manner, the phosphor can be applied to the outside or inside of the lamp, depending on the application. Applications can include a wide variety of disinfection processes for water or surfaces. The UV technology can also be used in medical device applications and procedures. Curved Three‐Dimensional Applications The microplasma lamp technology can also be used in curved‐surface products by using molded glass processes. These 3D lamps have a wide variety of design applications in the specialty and general lighting market.

Summary

Microplasma lighting technology is proving to be a valuable alternative in the specialty and general lighting industry. It is a true planar light source with specifications that match or surpass other technologies. Although it is one of the newest lighting technologies, its pace of development demonstrates that it is a viable choice for many applications. From under shelf, decorative and architectural lighting applications to more specialty sectors like appliance, transportation, and studio lighting, microplasma technology is starting to find its place in the lighting industry. Contact: For more information on Microplasma Planar Lamp Technology please contact Eden Park Illumination at: Eden Park Illumination 903 North Country Fair Drive Champaign, IL, USA 61821 Email: [email protected] Website: www.edenpark.com


Appendix

Typical Specifications for a Microplasma Lamp

Microplasma Planar Lamp Specifications

Specification Units 1x1 Lamp (30cmx30cm) Test Conditions & Notes

Photometric

Construction Nominal 12” square white‐light lighting tile

Distribution (forward/back) % 90/10±5

Percentage front/back is a design parameter that can be set during manufacture

Luminance cd/m2 8000 front side

CCT K 3000±200

CRI 82±2

Lifetime hrs. 50,000 30% lumen depreciation estimate

Surface luminance uniformity % 5 1 cm edge exclusion

Surface color uniformity ME 3‐step units ‐ MacAdam Ellipse

Dimming range % 30% ‐ 100%

Refresh rates (PRF) Hz >15,000

Electrical

Input Voltage V 120 VAC 50/60 Hz

Input Current A 1.4 estimate

Power W 165 estimate

Mechanical

Lighting tile dimensions cm (in.) 31.75 x 31.75 x 0.64 (12.50 x 12.50 x 0.25) physical outside dimensions

Lighting tile weight kg (lbs.) 1.28 (2.8) estimate

Power supply dimensions cm (in.) 7.6x3.8x10(3x1.5x4) case dimensions

Operating Environment

Temperature °C (°F) ‐18 to 50 (0 to 122) environment

Relative Humidity % 10 to 90 Non‐condensing environment

Operating Temperature °C (°F) ≤80 (175) 20°C and 40% R.H., vertical orientation, full power

Audible Noise dBA ≤34


Glossary

Microplasma Lighting The use of microplasma in the creation of flat panel general lighting was pioneered by Prof. Gary Eden and Sung‐Jin Park, PhD. Their patented technology uses many microplasma generators in a large array, which emit light through a clear, flat, transparent window. Color Rendering Index (CRI) CRI is a comparison of a light source's ability to accurately render the color of an object to that of a standard reference light source. The CRI scale is from 0 to 100, with a value of 100 indicating excellent color rendering. Sunlight and most incandescent lamps have CRI values of 100. Only compare the CRI values of light sources of roughly the same color temperature. Correlated Color Temperature (CCT) ‐ is the measure used to describe the relative color appearance of a white light source. CCT indicates whether a light source appears more yellow/gold/orange or more blue, in terms of the range of available shades of "white." CCT is given in Kelvin (unit of absolute temperature). 2700K is "Warm" and 5000K is "Cool". Efficacy Efficacy is a measure of light output (lumens) per watt of electrical power needed by the lamp to produce that light. Lumens are a measure of how much light is emitted. Watts indicate how much electrical power is consumed. Lumen Lumens are a unit of standard measurement (luminous flux) that is used to describe the total amount of light produced by a light source as perceived by the human eye. The more lumens, the brighter the light you see. You can use lumens to compare the brightness of any bulb, regardless of the technology behind it, and regardless of whether it's incandescent, CFL or LED. Luminous Flux The measure of the perceived power of light emitted in all directions. It differs from the measure of the total power of light emitted since luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light. In other words, luminous flux is a weighted sum of the emitted power at all wavelengths in the visible band. LED A light‐emitting diode (LED) is a semiconductor diode that emits light when an electrical current is applied in the forward direction of the device. The effect is a form of electroluminescence where incoherent and narrow‐spectrum light is emitted from the p‐n junction. OLED An organic light‐emitting diode (OLED) is an LED whose emissive electroluminescent layer is composed of a film of organic compounds.

Documents

Microplasma Planar Lighting-By Eden Park Illumination