COMBINED HEAD-UP AND HEAD-DOWN DISPLAY

摘要

1422315 Combined head-up and head-down display systems HUGHES AIRCRAFT CO 5 April 1974 [30 April 1973] 15174/74 Heading G2J A combined head-up and head-down display system for an aircraft comprises a display panel 20F, a semi-reflecting mirror 24 which reflects light from the panel towards a collimator 26, and a second,semi-reflecting mirror 18 positioned in the pilot's field of view so as to reflect light from the collimator 26 towards the pilot; the display panel 20F is also visible in the head-down position through the semi-reflecting mirror 24. The panel 20F is formed by the front face of a cathode ray tube 20, which receives information for head-up display and head-down display simultaneously or separately. The head-up display information is arranged to occupy only a central portion of the face 20F. A shutter 28 may be operated to cut out ambient light, which is incident on the face 20F through the collimator 26, when the display is being observed in the head-down position. A field flattening lens assembly (90), (96) may be permanently or removably positioned immediately in front of the face 20F in order to improve the precision of aim when observing a target in the head-up position. The fixed lens assembly (90) has a spherical centre portion which overlies the head-up display information on the face 20F, and a peripheral portion of progressively smaller curvature towards the edge of the lens. In case of failure of the cathode ray tube display system, one or more illuminable reticles may be provided. In Fig. 6 (not shown) a reticle (66) is removably positioned in front of the face 20F. In Fig. 7A (not shown) a reticle 72 is positioned below the mirror 24, which is dichroic and is illuminated by light of a wave length transmitted by the mirror 24. A second reticle (84) is mounted in the casing of the tube 20 and imaged on the face 20F.