| 摘要 |
A portable map-display system for auto, boat and airplane uses and the like includes a plurality of translucent maps and a compact light box proportioned for back-lighting one map at a time. To prevent unshielded glare from the light-box and to assure proper orientation of maps on the light-box a series circuit arrangement turns off the light circuit in the box when a map is not properly in place over the light-box. The series circuit arrangement includes a conductive strip asymmetrically disposed on each map and a pair of electrodes on the light-box adapted for resiliently receiving the conductive strip of a map between them to close the circuit and turn on the light.
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