Optics: image projectors – Reflector
Reexamination Certificate
1996-05-31
2001-05-01
Dowling, William (Department: 2851)
Optics: image projectors
Reflector
C353S013000, C359S451000, C434S044000
Reexamination Certificate
active
06224218
ABSTRACT:
GOVERNMENT RIGHTS
The present invention is made under a contract with the U.S. government. The government may have rights in this invention.
TECHNICAL FIELD
The present invention relates to display systems employed in aircraft simulator training systems.
BACKGROUND OF THE INVENTION
Various display systems are known for aircraft simulator applications used to train pilots and other aircraft crew members. The simulators allow training in a ground-based facility and attempt to provide simulated experiences and situations which are as close to actual events as possible. One of the drawbacks of present simulator systems is the limited field of view (FOV). The FOV is often insufficient to provide vision in the areas necessary for multiple training tasks, such as landing training and refueling training. These tasks in particular require the largest possible FOV display.
Preferred simulator systems today use an off-axis backscreen/mirror visual display system (OABD) for providing a large field of view display for the pilots and other crew members. The OABD systems use projectors which project an image onto a backscreen member which in turn redirects the image beam onto a collimating mirror. The mirror in turn redirects the beam to the observer's eyepoint.
The vertical FOV of OABD systems is normally limited since the portion of the backscreen that displays the lower portion of the FOV also blocks or occults the observers' upper FOV. Attempts to increase the FOV coverage in the downward direction have adversely affected (that is, decreased) the FOV coverage in the upward direction. Similarly, increases in the upward FOV coverage have decreased the FOV coverage in the downward direction.
Some attempts to overcome these limitations in current OABD system designs have moved the eyepoint of the observer forward and/or downward with respect to the display. Similarly, some systems have instead moved the display in a backward and/or upward direction with respect to the observer's eyepoint. These allow the downward FOV coverage of the backscreen to be increased; however the upward FOV coverage again becomes partially occulted by the backscreen. Moreover, moving the eyepoint or display thusly degrades the collimation (convergence and divergence) and/or distortion characteristics of the OABD system. This in turn can lead to significant problems with eyestrain or the ability to use the system.
It is an object of the present invention to provide an improved OABD system for use in aircraft simulator applications. It is another object of the present invention to provide an improved OABD system with an increased vertical field of view.
It is another object of the present invention to provide an OABD system with an increased vertical field of view which does not decrease the field of view in other directions or areas. It is still further object of the present invention to provide an improved OABD system which increases the field of view but does not degrade the collimation and/or distortion characteristics of the display.
SUMMARY OF THE INVENTION
The present invention overcomes the problems noted above with respect to known off-axis backscreen/mirror visual display systems (OABD) and provides a system which meets the above-stated objects. In particular, the present invention provides an OABD system having an increased vertical field of view (FOV) while preserving the collimation and distortion characteristics of the display.
The system includes a projector for projecting an image beam, a collimating mirror, and a backscreen interposed between the projector and the mirror for redirecting the image beam onto a surface of the collimating mirror. The collimated mirror in turn redirects the image beam to the observer's eyepoint. In accordance with the invention, the lower edge of the backscreen is contoured to approximate the field of view limits of an aircraft sill line. This contouring increases the usable vertical FOV without changing the geometrical relationship of the eyepoint, backscreen and mirror.
Preferably, a demarcation line is determined and used as a guide for contouring the bottom edge of the backscreen. Other additional occultation areas, such as those caused from other aircraft parts, both inside and outside of the cockpit, may also be taken advantage of and used to add or delete additional material to the backscreen during contouring. Also, for OABD systems that support dual eyepoints, the contouring takes into consideration the field of view of both the pilot/observer and the co-pilot/crew member.
The areas of the backscreen which are removed by the contouring of the bottom edge increase the vertical field of view in those areas.
These and other features, benefits and advantages of the present invention will become more apparent from the following detailed description of exemplary embodiments of the invention, as further illustrated in the accompanying drawings and as set forth in the appended claims.
REFERENCES:
patent: 3620592 (1971-11-01), Freeman
patent: 3784742 (1974-01-01), Burnham et al.
patent: 3807849 (1974-04-01), Lobb
patent: 3895861 (1975-07-01), Herndon
patent: 3973840 (1976-08-01), Jacobs et al.
patent: 4234891 (1980-11-01), Beck et al.
patent: 5566370 (1996-10-01), Young
patent: WO 96 14713A (1996-05-01), None
Dowling William
L-3 Communications Corporation
Whitman Breed Abbott & Morgan LLP
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