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LED - OLED Lamp Combination Disclosure Number: IPCOM000028343D
Publication Date: 2004-May-11
Document File: 7 page(s) / 98K

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LED - OLED Lamp Combination


Solid-state light sources are considered to revolutionaries the markets and applications of light sources. Inorganic LEDs are a reality already, while organic LEDs (OLEDs) for lighting just entered the development stage.

This document describes combinations of both technologies to complement each other in optimization of lamp properties. Lamps utilizing both technologies are ideally suited to deliver improvements with respect to lifetime, color rendering, light distribution, electronic supply and illuminance.

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LED - OLED Lamp Combination

Light-sources based on inorganic LED show a large variety of layouts and performance and its market share continuously expand. With integrated circuit for 12V power supply LED light sources can be easily combined with halogen lamps. Inorganic LED light sources do not emit white light. For a white light source a combination of at least four LEDs is required to cover the visible spectrum sufficiently resulting in an acceptable color rendering. The line width of light emission of inorganic LEDs is typically limited to a few tenth of nanometer. Fig. 1 shows typical emission spectra of inorganic LEDs, separated in nitrides and phosphides used for different wavelengths.

Fig. 1: typical LED emissions spectra

Inorganic blue and red LEDs are much more energy efficient compared to yellow and green LEDs. Additionally inorganic LEDs are very sensitive to the applied direction of current and will be easily damaged if operated in reverse direction. Inorganic LEDs can be considered as point light sources with an arbitrary emitting angle distribution.

Organic LEDs (OLEDs) exhibit a lot of complementary properties compared to inorganic LEDs.

- broad emissions spectra

- efficient emission in yellow and green spectral range

- robust against operation in reverse direction

- limited luminance

- large area emitters easy to manufacture.

- isotropic emission characteristics.

The specific emission properties of inorganic red and blue LEDs and organic yellow and green LEDs can be combined to develop white light sources. Organic electron/hole

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conducting and light emitting layer can be prepared on glass substrates covered by bottom and top layer electrodes. The electrodes can be structured to supply different lamp areas.

Additionally inorganic LEDs can be integrated into the glass plate. These LEDs can be electrically contacted directly through the organic layer or via additional conducting layers.

Fig. 22 shows a corresponding lamp.

Fig. 2: Integration of inorganic LEDs into a TL lamp for indirect light.

The desired lamp properties are widely adjustable by choice of LED components. Specific red/green/blue modules can be used to tune color temperature and color effects. Together with OLED components, the emission angle can be adjusted from diffuse to an angle < 60°.

With an optimized electronic layo...