| 摘要 |
<p>An information display system has a display screen (21, 26) which is substantially transparent to a selected band of wavelengths of light and can be mounted on a window (23). A projector (20, 25) projects an image of light of the wavelengths to which the display screen (21, 26) responds onto the screen to reflect or transmit the selected wavelengths of light from the screen (21, 26). The screen (21, 26) is formed as a holographic optical element which reflects the light such that an observer (24) is able to see the projected image from the display screen (21, 26) only if his eyes are within a predetermined area, while observers outside of the area see only a substantially transparent display screen (21, 26) on the window (23).</p> |
