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MOTOROLA Technical Developments Volume 4 April 1984
LIGHTING ARRANGEMENT FOR INSTRUMENTS
by Tom R. Kawall
This arrangement provides uniform lighting to the face of the instrument or gauge from a light source mounted behind the instrument face.
A one piece molded and hermetically sealable instrument housing in 10 in Fig. 1 has an integrally molded light bubble 11 into which is mounted a lamp 12 for illumination of the instrument face 13. The housing is preferrably a transparent plastic 14 (see Fig. 2) having high light transmittance and a vacuum metalized exterior plating 15 which operates as a light reflector. The transparent plastic material acts as a light pipe to direct illumination toward an angled reflective surface 16 which is disposed just forward of the instrument face 13. The angled reflector 16 reflects transmitted light to provide even illumination of the face 13.
The metalized plating 15 also provides protection of the interior of the instrument against electromagnetic interference.
?J Motorola, Inc. 1984 48
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2 Motorola, Inc. 1984 49
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