EL - FAQ

01)

What is an EL Lamp?
Electroluminescent (EL) Lamps are flexible, flat, thin, cold illumination sources that can be cut into complex shapes for lighting LCD displays, aircraft instrument panels, architectural accents, advertising signage, and special effects for movies, television, the theatre, and theme parks.

02)

How does EL work?
An EL device resembles a sandwich in that it is comprised of a light emitting material placed in between two insulating layers. This structure in turn is then placed between two conducting electrodes. A light emitter or phosphor- typically zinc sulfide doped with manganese, is placed in between the insulating layers. Aluminum and indium tin oxide (ITO), which is a transparent conductive metal, are used as the electrodes. When the voltage exceeds a well defined threshold, the emitter breaks down and conducts current. The current excites the manganese ions, which give off light.

03) What are the advantages of EL Lamp?
   
a)

Complex lamp shapes made to customer specifications; EL lamps can backlight the most intricate instrument panels and keypads

b)

Flat and flexible lighting systems are designed so they can be employed in difficult to reach areas or areas inaccessible with conventional lighting

c)

Cold light sources; electroluminescent lamps produce virtually no heat, making them ideal for use in areas where heat from conventional lighting is a problem (for example, backlighting heat sensitive transparencies).

d)

Comprehensive range of lamp colors; lamps can be manufactured in a wide range of colors to meet specific color correct or visual effects requirements.

04)

What are the drawbacks of EL lamp?
The main drawback with EL displays is that they currently cannot provide full colour. Full colour requires a good blue emitting phosphor, but none having suitable brightness, efficiency and longevity has yet been found. Research is being done to grow materials such as cerium doped strontium sulfide using a method called atomic layer epitaxy (ALE).

05)

What is the Operating Principle of EL?
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 allowing 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 number of light pulses depends on the magnitude of applied voltage, the brightness of EL lamps can generally be controlled by varying the operating voltage and frequency.

06)

Why should there be a need for a EL driver anyway?
EL is driven by AC power. It can be designed to be driven directly by 110V AC without adding any additional circuit. However, a lighted EL is of less use than a flashing one, which can catch the eyes attention. Therefore, we need to use software to control the flashing pattern, and this is what an EL driver is supposed to do. Another need is to convert low voltage DC power from the dry cells such as 6VDC, to over 110V AC, and this is also the job commonly found in EL driver.

07)

What are the features I can play with the EL in product design?
The nominal voltage and frequency for EL lamp 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. 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 to blue. However, increasing voltage and frequency will reduce lamp life.

08)

What is 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. 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.

09)

How can Lamp Brightness be defined?
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. Since buyers may not have the sensitive instrument to measure the brightness, we only can use a comparative approach and sample confirmation to finalize the brightness defined by the customer.

10)

How many segments of lighted area can Ideatech's EL driver control?
The IT-9361 is defined to control 5 ports. The standard interface is 7-pin, with common line on both ends. It means that regardless of how the consumers, who presumably do not know anything about electronics, will connect the male/female connectors in one way or another, and in both ways, the EL driver will work normally. The flashing pattern is just reversed.

11)

What are the flashing patterns?
For IT-9362, the flashing pattern is a simple sequential pattern, i.e., 1-2-3-4-5.... in this sequence, with one port flashing at any moment of time. In the IT-9361, it is a more advanced model, controlled by software, which means the customer can request the flashing in any sequence, repeat, in order to achieve the best visual impact on their brand or logo. Moreover, the IT-9361 has a pushbutton allowing user to select among 4 other standard patterns, such as sequential, random, roaming, queueing.

12)

What are the typical characteristics of EL lamp?
EL lamp can be designed to have a variety of characteristics, but just to let you have a rough idea of what it is, below are the standard characteristics. The actual characteristics are by no means limited by the parameters below :


Operating Voltage : 60-180Vac
Operating Frequency : 50-2000Hz
Brightness Range : See Table Below
Operating Temperature : 0 ... +50 degree C
Storage Temperature : -65 ... +85 degree C
Colors : See Table Below
Service Life : Approx. 1500 hours
Standard Thickness : 0.5mm
Weight : 0.1gm/cm2
Power Consumption : Approx. 2mW/cm2
Current Draw : Approx. 0.14mA/cm2

  Yellow Blue Green Green Blue Red
Brightness cd/m2 29 85 85 18 18
Wave lenght nm 586 500 506 455 613
13)

If my logo requires to be divided into more than 5 groups of patches, how can I make use of the Ideatech's Smart EL Driver?
The IT-9361 Smart EL Driver can be modified both in hardware and software to provide the control of up to 10 ports. Precisely how it can be done has to be discussed with us in details before a solution is suggested by Ideatech.

14)

What is the relation between the EL and the EL Driver?
The EL driver is the power source and the "brain" to control the flashing pattern of the EL. They are connected by standard interface, 7-pin male/female connector. When the garment is to be washed, just unplug the connector and take away the EL driver and the EL lamp from the garment. After the garment is dried, consumer can put back the EL and its driver.

 

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