Development
of an Electrophoretic Display Technology for Selectively Retroreflective Signs
and Pavement Markers
Christopher
Y. Brown; Thomas A. Brubaker; Andrew M. Churchill; Gregory M. Crosswhite; David Fried; Leslie Kirsch; Daniel A. Zelman;
and David J. Lovell, A.M. ASCE
Journal of
Transportation Engineering, vol. 141, No. 1, pp. 04014067-1-9
This paper describes an enabling technology that could be used to develop
electronic roadway signs and markers whose display content can be changed and
that are selectively retroreflective. This would give them the good visibility
of retroreflective signs at night, coupled with invisibility under
circumstances where they are not meant to be seen, thereby reducing both
confusion and light pollution. This paper describes how the half-silvered and
blackened glass beads that constitute the visible components of the display
were fabricated in the lab and derives their geometric optics, demonstrating
their retroreflective capabilities. The paper also describes the construction
of a transparent top electrode necessary to establish the electric field for
changing the displays and derives some of the electric properties of the
electrode and the resulting capacitorlike display.
The work is in an early developmental stage, and the paper concludes with an
outline of some of the remaining issues that need to be solved before a working
device could be constructed.