LED display

Details LED display LED display

2000-06-30

2002-12-10

O'Shea, Sandra (Department: 2875)

Illumination

Plural light sources

With support

C362S812000, C362S247000, C040S563000

Reexamination Certificate

active

06491412

ABSTRACT:

BACKGROUND
This invention relates to illuminated displays. More particularly, the invention relates to an illuminated sign using light emitting diodes (LEDs) as light sources.
Typically, illuminated signs use gas discharge lighting, such as neon. Also, it is common for illuminated signs to be illuminated by incandescent or fluorescent lamps. Both gas discharge and incandescent lamps have disadvantages. Incandescent lamps operate at a very high temperature, and gas discharge lamps require high voltage.
Further, incandescent lamps have a short life and run relatively inefficiently. Driving an incandescent lamp expends a great deal of energy for the level of brightness achieved. Gas discharge lamps are typically fragile and require an expensive ballast or power supply for operation.
Some have attempted to overcome the deficiencies of gas discharge or incandescent lamps in signs by using LEDs. In such signs, the LEDs typically face outward toward the observer. Because LEDs are a highly intense point light source, such signs tend to result in an uneven illumination of the sign, where areas of brightness or “hot spots” are surrounded by darker areas. Some have tried placing a diffuser in front of the sign to diffuse the inner light. Nevertheless, the sign still has uneven illumination. Thus, it is desirable to have an efficient and safe light source that results in even illumination of a sign.
SUMMARY OF THE INVENTION
Accordingly, the present invention is an energy-efficient, safely designed, evenly illuminated sign. The sign includes a housing having a plurality of internal surfaces, one of the internal surfaces being translucent. All of the internal surfaces except the translucent surface are diffusely reflective. At least one LED is positioned between the internal surfaces, where the LED is positioned such that the direction of the illumination field of the LED is substantially opposite to the translucent surface.
Accordingly, it is a feature and advantage of the invention to provide a highly efficient illumination source for a sign.
It is another feature and advantage of the invention to provide a safe illuminated sign.
It is another feature and advantage of the invention to provide an illuminated sign that provides even illumination over all portions of the sign.
It is another feature and advantage of the invention to provide an illuminated sign having a light source with a long light life.
It is another feature and advantage of the invention to provide an illuminated sign that is inexpensive and easy to manufacture.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.


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patent: 4439818 (1984-03-01), Scheib
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patent: 5105568 (1992-04-01), Branning
patent: 5167556 (1992-12-01), Stein
patent: 5469347 (1995-11-01), Duve et al.
patent: 5803579 (1998-09-01), Turnbull et al.

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