In a head-up display system video signals derived by a television (or infra-red) camera which is mounted on the aircraft nose to view substantially the same scene as viewed by the pilot along his line-of-sight through the partially-transparent reflector of the head-up display system, are mixed with the video signals which are supplied by a waveform generator in accordance with aircraft-attitude and weapon-aiming symbology that is used for projection onto the reflector. The combined signals, representing the external scene with the symbology superimposed, are supplied to a video-tape recorder for subsequent, or immediate, replay by a television monitor in the aircraft or via the pilot's head-up display unit, and are also supplied to a transmitter to enable recording and display to be carried out at a ground station. A second head-up display unit having its own waveform generator, is provided in the aircraft for use by an instructor during pilot training, and a mixer associated with this is supplied with the combined signals or with the camera signals alone. The combined signals may be used to intensify the view through the reflector of a pilot's head-up display unit used for a military mission, so as to ensure more ready identification of a target.

A remote readout unit in a weather-proof housing is mounted on the exterior front wall of a temperature controlled trailer truck in a position to be observed by the driver in his rear view mirror and from the ground when the vehicle is parked. The readout comprises three electro-magnetic seven-segment digitals arranged as a two digit indicator for the temperature within the trailer and a single character for indicating the current mode of operation of the refrigerating equipment. The unit, powered by the battery of the trailer, includes a sensing thermistor located in the trailer, connections to each of the three operational mode indicating lights of the refrigerating equipment and a micro-processor located within the housing which in repetitive cycles monitors the temperature and operational mode indicators, processes the information by a permanent program and updates the digital readouts, the latter being selectively determined by the position of a manual switch located on the housing to display the information in either a reverse image for viewing in a rear view mirror or a direct image for viewing from the ground.

A device for maintaining the vigilance of a motor vehicle operator. Two preferred embodiments, maintaining the operator's attention toward the direction of developing traffic conditions, with a visual system focused at infinity, are disclosed. One shows an image which is projected or otherwise transmitted from below the normal line of sight of the operator, while the other illustrates transmission of the image from above the vehicle operator. The invention overcomes "road hypnosis" or other inattentiveness by maintaining the operator's interest, thereby putting the operator's psychological perceptive apparatus in a high state of readiness.

A head-up display for use in an automotive or other vehicle having limited space. The optical path from display symbol generator to a collimating lens is folded to fit in a relatively compact housing. Also shown is the use of the automobile windshield as a combiner glass for the display. Corrective lenses, and in particular crossed linear fresnel lenses, are used to correct for the astigmatism introduced by the geometry of the windshield. This provides a combination of optical powers for the display lens and the windshield which has the resultant effect of projecting an image from the image source to the driver's eye. The source is a high light output array of light-emitting diodes. A microprocessor based controller for detecting the status of inputs from the automobile is shown. Data is periodically loaded into a random access memory dedicated to controlling the display. When data is not being loaded, a separate address and timing generator is used to cause data from this memory to be displayed in a free-running mode.

A method of operating a telescope is provided herein for a telescope having an eyepiece. The method uses a graphics display having a data base of celestial bodies, and means for generating and displaying a graphics display comprising graphics artefacts, each representing an associated celestial body. The method includes the first step of correlating, as a datum, the position of that telescope and the position of that graphics display corresponding to the field of view of the telescope. The second step involves displacing that graphics display or the position of the telescope to show an artefact representing a celestial body of interest. The third step involves detecting the effective distance moved in such displacing step. The final step involves either moving the telescope a corresponding distance, or changing that graphics display effectively to track movement of the telescope, respectively, such that the celestial body of interest is visible in the telescope eyepiece, and a corresponding graphics artifact is visible in that graphics display. Further in a preferred embodiment, that graphics display is superimposed on the telescope image in the eyepiece such that the graphics artifact is aligned with the celestial body of interest.