Operating Principle

Electroluminescent lamps are devices which convert electrical energy into light or luminescence; the term luminescence is generally associated with solids that generate light. In the case of electroluminescence, an electric field (voltage) is applied to a thin phosphor layer to produce light. The typical lamp consists of light emitting phosphor sandwiched between two conductive electrodes (one of the electrodes is optically clear to allow light to escape). As an AC voltage is applied to the electrodes, the electric field causes the phosphor to rapidly charge and discharge, resulting in the emission of light during each cycle. Since the size and number of light pulses depends on the magnitude of applied voltage and frequency, the brightness of EL lamps can generally be controlled by varying the operating voltage and frequency.

Voltage and Frequency

The nominal voltage and frequency for EL lamps are 115 Volts and 400 Hertz (Hz). These values originated from the initial aircraft use of EL lamps and represent the standard voltage and frequency in aircraft. However, EL lamp operation is not tied to these values and Lumitek lamps can be tailored for operation between 40 to 220 Volts (AC) and 50 to 5000 Hz. Varying the lamp voltage or frequency will change the lamp brightness and, to some extent, the color. For example, increasing the voltage increases lamp brightness, whereas increasing the frequency will increase lamp brightness and shift the color slightly toward blue. However, increasing voltage and frequency will reduce lamp life; our engineers can determine the optimum condition for your application.

Lamp Life

Unlike filament or fluorescent lamps, EL lamps do not catastrophically or abruptly fail. Instead the lamp brightness will gradually decrease over long periods of use. EL lamp life is affected by voltage, frequency, temperature, and humidity. Humidity is by far the strongest contributor to shortened lamp life unless special manufacturing processes are employed; Lumitek lamps are constructed so as to minimize the effects of humidity on lamp life. However, even in the absence of humidity, the phosphor itself will gradually lose its efficiency over time and the lamp brightness will gradually decrease. Unfortunately, quantifying lamp life is difficult because of variations in use, environment and operating conditions. Generally, lamp life can be defined in terms of the time it takes the lamp brightness to decrease to a percentage of its original value under well defined operating conditions. Lumitek specifies the half-life of its lamps (i.e., the time it takes for the brightness to decrease to one-half its original value) and the limiting life (the time it takes for the lamp brightness to decrease to 1% of its original value).

Lamp Brightness

The light output of a lamp can be measured in terms of radiometric or photometric quantities. Radiometric quantities measure the total light output power of the lamp, regardless of wavelength. However, the human eye does not sense all wavelengths. Therefore, EL lamp brightness, or luminance, is usually specified in terms of photometric units, which account for the eyes’ sensitivity. Values of luminance are usually given in units of Foot-Lambert [FL] i.e. [lm/ft2], or [Apostilb] i.e. [lm/m2], or [Nit] i.e. Candela/m2 [Cd/m2], etc.

Lamp Color

Lamp color is usually specified in terms of CIE color coordinates or apparent color temperature. Variations in lamp colors can be obtained in one of four ways. First, the primary lamp color is determined by the phosphor type. Typical standard phosphor colors are blue, blue-green, and green. In certain cases, a color different from available primary phosphor colors is required. In such cases, the color can be obtained by blending multiple phosphors, adding fluorescent dyes to the phosphor layer, or by attaching a color filter to the lamp. Phosphor blending is the least desirable method since not all phosphor types have the same brightness, lifetime, and operating characteristic. Therefore, if multiple phosphor types are mixed, the color could be unstable and subject to change over time. In order to obtain stable colors different from standard phosphors, Lumitek employs either a dye addition to the phosphor layer or overlays a suitable color filter on the lamp. With the first process, the phosphor’s layer primary color causes the dye to fluoresce at a different color. By careful selection of the dye and primary phosphor, the color of choice is obtained. The second method involves overlaying a suitable color filter on the lamp which sharpens the lamp color; this process is employed to obtain other colors such as NVG (night vision goggle) – compatible green. With these approaches, Lumitek can obtain a wide range of lamp colors meeting various lighting color requirements.EL Lamp Power Source

Since EL lamps generally require drive voltages and frequencies not available from batteries or AC line voltage, a conversion is needed to obtain optimum color and brightness. For battery operation, a DC-to-AC voltage frequency inverter is needed. In order to meet varying use requirements, Lumitek provides a wide range of inverter and converter packages for EL lamp operation from DC voltage (e.g., batteries) or AC line voltage; our engineers can determine the optimum configuration for your needs.

Weight and Thickness

One of the key design attractions of EL lamps is their low weight and thicknesses. The weight of a typical Lumitek EL lamp is a mere 0.1 grams.cm2 (.001 lb/in2) and the nominal thickness is 0.5 mm (0.020″). For certain specialized applications, the weight and thickness can be reduced by about 60%.

Minimum Bend Radius

Another benefit of EL lamps is that they are flexible. Typically, a bend radius of ~4 cm (1.5″) can be achieved. However, the bend should only be a single axis curve and thermal forming is not recommended.

Edge Seals / Bus Bars

A minimum protective edge seal of 1 mm (0.040″) can be guaranteed from the lamps’ lit edge. However, small edge seals have a dramatic effect on unit cost and lamp life, therefore, a seal width of 2.0 mm (0.080″) is recommended. This is seldom a concern since Lumitek EL lamps have the advantage of no electrode setback for the use of bus bar networks on the front (light-emitting side). This maximizes edge seal specification flexibility, as well as providing a more pleasing lamp appearance.

Color Options

Lumitek Lamps are available in a wide range of standard single, mixed, and filtered colors; in addition to those listed below, Lumitek also offers custom colors to meet specific requests (our engineers can develop colors not listed below).

-Standard : Aviation Green, Blue-Green, and Blue.
-Dye Modified: White, High-Visibility Green (chartreuse).
-Filtered: NVG Green, or other colors (using color correction filters to meet customer needs).

Phosphor Type

Unless specified, Lumitek manufactures all lamps with long-life micro-encapsulated phosphor. For the specific phosphor type most suitable for your application, consult our sales staff.

Sizes

Lumitek manufactures lamps to each customer’s specifications so typically there are no standard sizes. A tooling charge is normally applied to the first order and a drawing is required. Our engineering staff will work with you to develop any drawings if necessary. Consult our sales staff about configurations / sizes.

Cables / Connectors

All Lumitek Lamps can be provided with the following choice of cables and connectors:

-*Solder Pins
-*Ribbon Cable / Solder Pins
-*Ribbon Cable / Mate+Latch
-*Phosphor Bronze Foil
-*Ribbon Cable / Dupont Plug
-*Other connector type can also be specified (consult our sales staff)

Lamp Inverter / Converter Packages

DC Source Voltage Operation: Lumitek Lamps can be provided with a DC-to-AC inverter for battery powered applications. The inverters are offered as stand-alone components for customer installation, packaged for direct lamp hookup, or pre-wired to lamps.

Line Voltage Operation: Lumitek Lamps can be provided with AC/AC frequency converters. These can be provided as stand-alone components or pre-wired with AC line voltage plug for easy use.

Functions: Any of the inverter/converter packages can be provided with motion sequencing, blinking, or dimming functions for either DC or AC power sources.

All electronic drivers are manufactured to match specific lamp sizes and varying customer requirements. For specific needs, please consult our sales staff.

General

Lamp type:	Flexible Thick Film AC
Cover Film:	PCTFE (Aclar®; a registered trademark of Allied Signal, Inc.)
Brightness Uniformity:	± 15% (Typical; tighter tolerances possible upon request)
CIE Chromaticity (x,y):	± .03 (Typical; tighter tolerances possible upon request)
Half Brightness Time:	3,000 – 5,000 hours
Useful Life:	> 10,000 hours

 

Electrical

Nominal Lamp Operating Voltage:	115 Volts AC
Nominal Lamp Operating Frequency:	400 Hz
Max. Lamp Operating Voltage:	140 Volts AC
Max. Operating Voltage Option:	220 Volts AC *
Max. Lamp Operating Frequency:	800 Hz
Max. Operating Frequency Option:	5000 Hz*
Lamp Capacitance:	~3 nF/in2 (@ 115 Volts, 400 Hz)
Current Draw:	~0.9 mA/in2 (@ 115 Volts, 400 Hz)
DC Power Option:	DC /AC Custom Inverter
AC Power Option:	AC/AC Custom Converter

* for Lamp operation above 140 Volts or 800 Hz, the exact operating conditions must be specified.

CIE Color Coordinates

	x (±0.03)	y (±0.03)
Green	0.180	0.430
Blue-Green	0.180	0.370
Blue	0.160	0.200
Pink-White	0.310	0.380
Warm -Pink-White	0.360	0.360
HiVis	0.200	0.600
NVIS GREEN A	u’=0.088	v’=0.543 | r=0.037

Other colors are also available.

 

Mechanical

Max. Size (standard):	10″ X 20″ (254 mm X 508 mm)
Min. Size:	0.25″ X 0.25″ (6.3 mm X 6.3 mm)
Nominal Thickness:	0.020″ (0.5 mm)
Min. Thickness Option:	0.0075″ (0.2 mm)
Nominal Edge Seal:	0.08″ (2 mm)
Min. Edge Seal Option:	0.03″ (0.76 mm)
Bend Radius:	1.5″ (38.1 mm)

Environmental

Operating Temperature:	-50°C to 65°C
Storage:	-50°C to 85°C; for prolonged storage, lamps should be stored in a sealed bag with a desiccant pack
Chemical Resistance:	The Aclar® cover film resists a wide range of industrial chemicals and solvents (your sales engineer can provide a list of specific chemicals); if lamps are specified with exposed leads, they should not come in contact with corrosive materials.

Example Data Curves