is formed as a film of light transmissive plastic material, which
film comprises a micro-structured surface portion and an attachment
surface opposite to the micro-structured surface portion, the film being
adapted for attachment to one of the top and bottom surfaces so as to
form at least part of the incoupling, by the micro-structured surface
portion being arranged to transmit light that has an angle of incidence
enabling light propagation by total internal reflection inside the panel.

21. An optical touch panel for a touch-sensitive apparatus, wherein the
optical touch panel comprises parallel top and bottom surfaces and is
arranged to propagate light by total internal reflection from an
incoupling site to an outcoupling site, wherein the optical touch panel
further comprises a micro-structured surface portion which is formed on
one of the top and bottom surfaces to define theThe ancestor of GPS

This device is a old form of GPS and it appeared first in England in the twenties under name 'RouteFinder'. When the rolls showing a map were inserted in the device, one only had to follow their instructions while turning a wheel as the way advanced.

A few years later a new, better device came out. It was bigger, easier to read and could be integrated in the car.