| 摘要 |
<p>A navigation device is disclosed, having a lens (6) across an opening at one end of a case (2, 12), and a compass (14) across an opening at the opposite end of the case. A transparency holder (8) is positioned between the lens and the compass, adapted to receive a map transparency (10) with magnetic north thereon aligning with a North marking (19) on the case or on the body of the compass, at a distance from the lens approximating the focal length of the lens. A grid wheel (22) is provided between the transparency holder and the compass, having a transparent or translucent central area inscribed with parallel grid lines (34) and at least one first directional arrow (36) aligned parallel to the grid lines, the grid wheel being in close proximity to the transparency holder such that it is also at a distance from the lens approximating the focal length of the lens. Positioned between the grid wheel and the compass, and geared to the grid wheel for counter-rotation therewith, is a direction wheel (24) having a transparent or translucent central area inscribed with at least one second directional arrow (40). The transparency holder has asymmetric features, such as off-centre notches (88) which engage complementary features (86) in the navigation device. In the preferred embodiment, the transparency holder has integral upper and lower halves (90, 91) hinged together by a living hinge (92) and sandwiching the map transparency therebetween.</p> |
