| 摘要 |
<p>Assembly comprising a coded substrate which may be read from a distance (several metres) by a scanning device comprising a beam oscillating in a given sector and a coupled analyzer for the reflected light. The substrate comprises back-reflecting areas of substantially equal intensity, the difference between them being related to the chromatic content of the reflected light or, the latter being circularly polarized, to the direction of said polarization. In another case, certain coded areas diffuse the light along a conical divergent beam, other areas sending back the reflected signal in a direction substantially parallel to that of the incident beam. Application to a transceiver system (44) arranged on board a vehicle for reading road signs. It comprises a light source (55), a first semi-reflecting blade (56), an objective (57) intended to form a thin vertical light beam. While running, the vehicle causes the scanning of a back-reflecting surface (53) capable of changing the polarization of the incident light and carrying a coded signalling indication. A second semi-reflecting blade (58) is arranged in the path of the back-reflected beam and directs said beam onto two polarizing analyzers (59, 60) associated with two respective polarization sensors (61, 62) forming signals (A, B) sent to an AND gate (63) and to an interpretation unit (65) which sends the decoded indication to a display (66).</p> |
