Competitive Analysis of Commercial Lighting Technologies
Fluorescent tubes
The most recent development from fluorescent tube manufacturers has been the T5 tube. Deliberately differentiated from its predecessors, the T8 and T12 lamps, by being manufactured in different lengths and therefore not reusable in existing fixtures, the T5 lamp technology, as with all fluorescent tubes, generates UV light from a low-pressure mercury-based discharge. This UV light impinges against tri-phosphor coatings on the inner glass wall of the tube, and by photo luminescent conversion within the excited phosphors, the UV is converted to visible light.
Measured within a laboratory test fixture, a T5 tube can produce many lumens/ Watt of electrical energy at the lamp at 35 degrees C, but when measured in assembled “real world” luminaires, this perceived efficiency can drop dramatically. Typical office-style luminaires using T5 lamps with internal baffles to prevent glare can measure a delivered light efficiency as low as 40 lumens/circuit Watt.
When incorporated into high-bay fittings, the luminaires are constrained by the absolute flux levels that can be achieved within the system. The T5 lamp itself is not an ideal component for use in a reflector-based system as the lamp itself will absorb light reflected towards it from a luminaire reflector. T5 lamps are best suited to low-height area fittings, and not to high point-source fittings.
T5 lamps use mercury, and all lamps must have special handling at the end of their lives to ensure environmentally safe disposal.
Ceravision’s High Efficiency Plasma Technology is more efficient than Fluorescent Tube technology and in addition it will require half the number of fittings to provide the same light levels.
Light Emitting Diodes (LEDs)
The semiconductor LEDs that are used in lighting products are manufactured in two basic families: low power and high power chip designs. Low power lamps are available in T1 and T1.75 leaded packages as well as SMD versions and are based on individual LED dice with area dimensions of typically 0.3mm x 0.3mm. High power LED devices use highly structured, thin LED dice with chip area dimensions of 1.0mm x 1.0mm or higher, mounted on metal block assemblies in custom packages to help extract as much heat as possible from the semiconductor chip itself.
Each individual semiconductor LED chip can only have a monochrome emission, so to make a broadband emission device, either multiple chips of different colours must be used, with white light requiring at least three colours (trichroic colour) or a reduced gamut quasi-white light can be generated by over coating a blue LED chip with yellow phosphor (dichroic). Some of the blue light emitted by the LED is converted by photoluminescence into yellow light, and the eye perceives the mixture of blue and yellow as being a modest quality “white” light.
Individual LED chips are inherently power limited – low power chips limited to around 1/3 Watt per device, and high-power chips limited to 1-5 Watts per device, dependent on chip size and manufacturer. To compete against commercial lighting high-power luminaires using plasma or other discharge technologies, LED luminaires must use large numbers of clustered devices. The dissipated power of an LED luminaire is highly dependent on ambient temperature, and as the temperature rises from 25 degrees C, so the power dissipated within each chip of the luminaire must be reduced or its operating lifetime will be severely compromised.
Even though it has been in practice for more than 40 years, the semiconductor process used to make LEDs still results in variations of LED hue and intensity across each manufactured wafer of devices, so each packaged chip is “binned” for brightness and colour hue. Manufacturers seeking to make clustered LED assemblies for luminaires must either operate controlled binning techniques, or develop complex colour control circuitry to compensate for these differences. Simpler LED clusters with no colour control circuitry can quickly suffer from differential aging of the different LED colours, so the perceived luminaire colour may shift noticeably over time.
LED chip efficiencies of 45 lumens per Watt in commercial devices and 130+ lumens per Watt in laboratory devices are reported, but the LED technology still remains unable to deliver high flux levels from a relatively tiny point source. This inability to deliver multiple tens of thousands of Lumens per cm3 limits the suitability of LEDs for cost sensitive commercial lighting applications.
Ceravision's High Efficiency Plasma technology overcomes all of the shortcomings of LED technology. HEP is more efficient, can work at powers between 100w and 5kw and can provide complete solutions at competitive prices.
Ceramic Metal Halide (CMH) (and other discharge technologies including Metal Halide, Sodium High Pressure and Mercury Vapour)
Ceramic Metal Halide (CMH) is emerging as the most competitive of the traditional discharge technologies in the marketplace. It has been displacing Metal Halide, Sodium High Pressure and Mercury Vapour lamps from many traditional applications due to its improved efficiency and colour rendering compared to the incumbent technologies.
CMH is an electroded metal halide discharge lamp, built within a glass envelope, that can have energy coupled into the lamp at mains supply frequency (50-60 Hz) for low-cost, or with square wave drive from electronic drive circuits for higher system efficiencies.
CMH lamps can have good colour rendering (Ra between 80 and 93 claimed), and are available in a wide range of power levels, but the lumen maintenance over time offered is poor (75% typical), re-strike can take up to 30 minutes and in most instances cannot be dimmed.
In addition, the source size is modest for use in optical reflector systems, leading to optical efficiencies of 83-85% for complete luminaires (compares with 93% optical efficiency for Ceravision HEP plasma luminaire)
Ceravision's High Efficiency Plasma technology is more efficient, has better lumen maintenance can be dimmed to 20%. It has a re-strike capability of less than 60 seconds and is able to reduce the number of existing CMH/MH fittings by at least half giving substantial energy savings.
Standard RF powered electrodeless Plasma Lamp Technology
Standard RF powered electrodeless Plasma Lamp technology was first invented a number of years ago and has been exploited commercially by at least one overseas manufacturer. The system comprises a quartz glass bulb mounted within a metal-coated ceramic waveguide. RF energy is coupled into the waveguide, and the resulting high electric field excites the contents of the bulb to generate a sustained plasma channel. If the bulb contains metal halide salts, these will be vaporised by the plasma and broadband light emission will occur.
Ceravision abandoned its own development of the standard Plasma Lamp system for general illumination in favour of its unique patented High Efficiency Plasma system after several inherent weaknesses were identified:
- The standard Plasma Lamp process efficiently generates light, but only 20-25% of the light can be harvested for use due to the opacity of the metal-coated ceramic waveguide.
- The small size of the glass burner limits the power levels that can be implemented – exceeding these levels destroys the burner.
- The point source of light generated is useful for projection optics, but of little use for general optical designs where an isotropic light source is required.
The standard plasma lamp technology has been irrevocably superseded by the introduction of Ceravision's vastly superior High Efficiency Plasma technology.
Ceravision's High Efficiency Plasma technology delivers unrivalled energy efficiency, can work at power levels up to 5Kw and produces solutions at prices competitive with existing products.
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