| 摘要 |
<p>In an analogue indicating device (e.g. a clock) in which the relative position of two relatively movable components (Figs. 1-3: 26/28 and 12) is judged by the position of a reference marker (30/32) on one of the components (26/28) in relation to an adjacent scale (48) on the other component (12), the scale is constituted by a hologram (in 12) which when illuminated by a predetermined reference light (33) portrays a desired image of the scale (48) against which the reference marker (26/28) is seen. That image may also portray an environment (34) (e.g. a clock case) in which the scale (48) appears to be contained. The reference marker (26/28) may also be constituted by a hologram for portraying a holographic image of the reference marker. Alternatively, a holographically portrayed reference marker may cooperate with a real scale. The holographically produced image is preferably coplanar with the other image, whether the latter image be real or holographically produced, so as to eliminate parallax errors. Any suitable form of hologram may be used. The use of the invention in relation to time-keeping devices (Figs 1-3), electrical indicating instruments (Figs 4-5), dimension measuring devices (Figs 16-21 and 28-31), and operating mode adjusters (Figs 14, 15, 22, 23) and selectors (Figs 24-27) is described.</p> |
