Patent GB-1066008-A (GB)
Title: Navigational situation display
Inventor: GUTTMAN ERICH SAMUEL
IPC: G01S1/02
Filed: 1965-09-03
Abstract: 1,066,008. Maps. INTERNATIONAL STANDARD ELECTRIC CORPORATION. Sept. 3, 1965, No. 37666/65. Heading G5G. [Also in Division G2] A navigation display instrument to display the data recorded on a film, such as a micromap transparency, includes a translucent rear projection screen 104, a computer-controlled film-holder which forms the film into a cylinder 208 rotatable about and movable along its central axis, a lamphouse (411), as in Fig. 4 (not shown), located externally to the cylinder, and an optical system within the cylinder to project the light-beam from lamphouse (411) on to the screen, there also being first and second servomechanisms to rotate and axially displace the cylinder in response to first and second signals to permit projections of selected portions of the film. The optical system has a folded lens system adjustable to select high- or low-power magnifications and a diaphragm 306 to maintain constant screen illumination for either power. Lenses (304) and (1204), Fig. 13 (not shown), are swung into position on turret (1201) by motor (1301) and gears (1202, 1203). Reticle 207 indicates the aircraft heading and is rotatable by a servo-mechanism, or the reticle may be fixed and the transparency image rotated by means of the double dove prism 313 which is rotatable by the reticle drive mechanism. Optical components with aspherical surfaces remove field curvature due to the cylindrical film surface. Mirror surfaces are coated with silicon monoxide, and lenses with magnesium fluoride. Lamphouse.-A small-diameter high-intensity lamp (401) is placed slightly above the centre of curvature of cold spherical back reflector (402) to give an image beside the lamp and double the light entering wide-angle condenser lens group (404). The double image is re-focused at (408), and prism (406) and lens (407) of high refractive index provide a wide-angle beam for transparency (208). Cooling is provided by infra-red absorbing or transmitting dichroic coatings, and by filter plate (409) cooled by air from a blower. Cover (411) and heat shield (410) form a duct for air from the high-speed blower. and a glass epoxy heat shield (413) with an aluminium coating nearest condensers (404) is used. Lamp replacement during operation is possible by means of the double lamp carriage (501), as in Fig. 5 (not shown), which is withdrawn, reversed, and replaced. Microswitch (504) breaks the lamp circuit as the carriage is withdrawn to prevent arcing. The map transparency is a film-strip wound on to drum 208, the dovetailed ends being joined by binding tape. The drum rotates with changing longitude and shifts axially with latitude change, voltage inputs (201) denoting heading, latitude, and longitude being fed from a navigational computer via control box (202) to heading servo drive (203), latitude conversion servo (204), and longitude drive servo (205) respectively, as in Fig. 2 (not shown). High- and low-speed drives (219), (220) in longitude and (221), (222) in latitude, provide low-speed automatic drum motion at X30 magnification, and fast manual slewing at X10.