A tricky one, in my opinion. 'Transparanten' could mean either the actual signs themselves, implemented for example as transparencies or foils for use in safety signage lichting fixtures, or the fixtures themselves (see the reference below). My take would be the latter, but I'm not sure. 'Transparencies' would be an obvious translation, but it might be better to play it safe and use a somewhat broader term like transparent safety signage, for example.

http://www.google.com/patents/US8024880
ABSTRACT
A combination exit sign and emergency light is provided, wherein the emergency light is disposed along a bottom, portion of the exit sign. The bottom portion of the housing is formed with a recessed section intermediate opposing side flange portions, with a light bar incorporating LEDs being mounted in the recess section to provide emergency lighting during power outages and emergency situations. The bar is white in color on the outside, except a bottom portion of the bar is left clear for the free transmission of light. With this construction, at least a substantial majority of fight generated by the LEDs will be directed out of the bottom portion, while the side portions are also preferably lit thereby providing a more intense light out of the bottom portion to assure adequate illumination leading to a suitable exit.

Some other references that may be of interest:
http://www.a-spe.com/transparent-lll-signs.html
http://www.comedd.fraunhofer.de/content/dam/comedd/common/pr...
http://www.liton.com/webcatalog/listall.asp?sid=69
http://www.alibaba.com/product-gs/480158760/Adhesive_transpa...



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Note added at 5 days (2013-07-29 07:45:41 GMT) Post-grading
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@Asker: You're welcome, Will!