Integrated Light Pipe Retention and Shield
Publication Date: 2010-Aug-31
The IP.com Prior Art Database
Disclosed is a new design for a light pipe and compliant grommet press fit into a thin sheet. There are many different types of light pipe/grommet combinations. This one is set apart by using a specific light pipe design in combination with a properly sized compliant grommet in such a way that it attenuates light from LEDs in close proximity to the indicating LED.
This invention provides a low-cost method of installing multiple light pipes on a very tight pitch. The combination of the light pipe and grommet geometry provides light attenuation without the need for expensive/complex housings for individual LEDs. Additionally, the grommet can be made out of a fire retardant material to lower the flammability of the overall design.
This design incorporates a solid transparent core and a compliant grommet. The grommet is inserted into sheet metal, or other similar thin material, and the transparent core is inserted after. The two parts interface in such a way that the assembly is tightly retained once both are installed.
Typical light pipe/grommet designs use a stiff grommet (PC/ABS,
material). These grommets need discrete fingers that grip the inserted core because of the stiffness of the grommet material. By using a compliant material, such as Santoprene*, 360 degree shielding of the light pipe can be accomplished preventing light bleeding into the pipe through the openings between grommet fingers.
In the total design, two levels of light attenuation occur to allow light pipes on a tight pitch. The first is in the shielding provided by the compliant grommet, and second is by the shape of the transparent core (see Figures 1-4 below):
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