Limelite incorporates the highest quality thin film electroluminescent light emitting capacitors (LECs) with innovative “smart” driver technologies. The combination of these two components creates a highly visible and ultra energy efficient light source with a long lifetime.
What is electroluminescence?
Electroluminescence occurs when photons (i.e. light) are emitted from a material through excited electrons that are induced by an electrical current or field. In fact, both light emitting diodes (LEDs) and LECs fall under the category of electroluminescence. However, there is a significant difference between the two technologies: LEDs emit light using a direct electrical current through a diode structure which allows current to pass only in one direction, while LECs emit light using an alternating electric field through a capacitor structure which allows for small amounts of leakage current to pass through in two directions. Since power consumption is directly related to how much electrical current is consumed, diode based LEDs use much more energy than capacitive LECs.
What is a light emitting capacitor (LEC)?
The structure of a LEC is very similar to a traditional capacitor, in that there are two conductive plates with a dielectric (non-conductive) material in between them. In a LEC, however, there is an additional layer comprised of a phosphorescent material that can be excited with an electric field to emit light. The type of phosphor used to make the lamp determine the color and wavelength of the light emitted by the LEC. Limelite uses a printing process to pattern the dielectrics, phosphors, and metals onto flexible plastic substrates to create the lamps used in our products. One of the electrode substrates used in LECs is typically a transparent conductor, such as indium tin oxide (ITO), so that the light emitted from the phosphor can be emitted through the surface of the entire capacitor area.
There are several reasons why LECs are preferable to LED based technologies, especially for safety lighting applications:
- Energy Efficiency – since LECs use electric fields in a capacitor structure to light up an entire area instead of discrete points of light, less energy is required to produce the requisite amount of light for a properly functioning safety lighting product
- Visibility – because the entire surface area of the lamp is emitting light, LECs are a much more uniform and visible light source
- Reliability – LECs can operate at higher temperatures than competing thin film LED technologies (such as OLED)
- Lifetime – since LECs push less current through the light emitting material and do not need to be run at high wattages, the lifetime of code compliance for safety lighting applications is longer than LED based products
Limelite is currently leveraging the benefits of LEC technology in our two main product lines: 1) egress safety lighting (i.e. exit signs), and 2) residential night lights. In both of these applications, the benefits of energy efficiency, visibility, reliability, and lifetime are paramount. In contrast, Limelite’s technologies are not ideally suited for general lighting applications, where large amounts of light are necessary to illuminate another object and the light is reflected back to the end user. Therefore, we will focus our efforts on applications where our advantages are the most important. These applications include display type technologies where the user interacts with the final product by directly looking at the light source such as display and signage applications. This is where Limelite shines due to the way that our products emit a uniform and highly visible light in a larger area than is possible with discrete components. While Limelite will focus on safety egress lighting products, we are currently investigating other applications in the following areas: 1) automotive, 2) aerospace, and 3) general displays and signage for consumer electronics.