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High Efficiency Electroluminescent Diodes

IP.com Disclosure Number: IPCOM000092638D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Shah, BR: AUTHOR

Abstract

The electroluminescent diode has an improved efficiency. The diode has an N-type region 2 and a P-type region 3 located between two electrodes 4 and 5. When an electrical signal is applied to the terminals,light is formed in the diode and is emitted along its edges.

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High Efficiency Electroluminescent Diodes

The electroluminescent diode has an improved efficiency. The diode has an N-type region 2 and a P-type region 3 located between two electrodes 4 and 5. When an electrical signal is applied to the terminals,light is formed in the diode and is emitted along its edges.

One cause of diode inefficiency is the fact that some of the light strikes the terminals where it tends to be absorbed. Terminals 4 and 5 are constructed with their inwardly facing surfaces highly reflective. With this arrangement, light that otherwise would be absorbed is reflected toward the edge of the diode. To enhance this effect, the terminals can be given a convex shape.

Light that strikes the diode edges at an angle that is greater than a critical value is refracted inwardly. With diodes that are formed in conventional rectangular shapes, an appreciable amount of light strikes the edges at an angle that is large enough to cause internal refraction. This diode is constructed with cylindrical edges. More of the light is normal to these cylindrical edges and very little is refracted inwardly.

The diode assembly includes reflector 6. The latter is generally parabolic except that its shape is modified to account for the fact that the light is emitted from a cylindrical surface and not from a point source. When a point source of light is located at the focus of a parabolic reflector, light is reflected along parallel lines. The cross sectional line of the re...