Computer graphics processing and selective visual display system – Image superposition by optical means – Operator body-mounted heads-up display
Reexamination Certificate
2000-03-07
2002-08-20
Saras, Steven (Department: 2775)
Computer graphics processing and selective visual display system
Image superposition by optical means
Operator body-mounted heads-up display
C348S115000, C348S121000, C434S044000
Reexamination Certificate
active
06437759
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to vehicle simulators and more particularly to vehicle simulators having head-up displays.
It is known in the art to use vehicle simulators, such as aircraft flight or tank simulators, to train operators of such vehicles.
With respect especially to aircraft flight simulators, many aircraft, particularly fighter aircraft, have head-up displays which enable a pilot to view the outside environment in front of the aircraft together with information which is typically displayed on an instrument panel of the aircraft. The head-up display enables the pilot to observe a scene outside the aircraft (i.e., an “out-the-window” (OTW) scene) and at the same time to see, i.e., in superposition with the OTW scene, information (“symbology”), which the pilot may need, such as altitude, speed, a pointer to a target, etc.
An example of one such head-up display (HUD) is shown in
FIG. 1
wherein a head-up display (HUD) optical system
10
projects information provided on the HUD's display device, such as a cathode ray tube (CRT)
12
, to the eye
14
of an observer through an optical system
16
. The optical system
16
is used to collimate the images (“symbology”), e.g., alphanumeric characters, lines, target pointers, etc.) produced on the HUD display device
12
. The collimated HUD images are then viewed in superposition with the OTW imagery through the beamsplitter
18
.
The HUD system
10
in the aircraft shown in
FIG. 1
is focused at infinity (i.e., collimated) because the OTW scene being observed by the pilot is also typically at “infinity”. In the HUD system
10
shown in
FIG. 1
, if the pilot moves his head to the right, for example, not only does the target he is observing move to the right, but the symbology on the beamsplitter
18
, such an example a pointer generated by the HUD
10
pointing to a target, also appears at the eye
14
to move to the right on the beamsplitter
18
, thereby remaining on the target.
Referring to
FIG. 2
, a flight simulator
19
of the prior art is shown. The simulator
19
has the cockpit portion
21
of the aircraft, including has a HUD system
10
. Simulator
19
includes a projector
24
driven by an image generator
26
to produce the simulated OTW scene, and the generated OTW scene is projected by the projector
24
onto a screen
28
for observation by the pilot being trained.
In the simulator, as in the real world, an acceptable superposition of the HUD and OTW imagery occurs when the two images are focused at the same distance. The screen
28
, however, is not at infinity but relatively close to the eye
14
of the pilot, and consequently, the actual vehicle's HUD, which is focused at infinity for use in a real environment, cannot be used without modification.
One approach for making a HUD for such a simulator is to modify the optical system in the HUD
10
so that it focuses at the same distance from the eye
14
as the screen
28
, i.e., such that the optical system
16
of the HUD
10
makes the symbology appear to the eye
14
as if it were located on the screen
28
. The HUD optical system
16
must be modified so that a simulated, distant target being projected on the screen
28
, and a symbology pointer (generated by the HUD
10
) pointing to the target (which is generated on the OTW screen
28
) appear co-located wherever the pilot in the simulator moves his head.
One problem with this design is that each different type of aircraft usually has a different HUD type, or multiple HUD types, and simulators for a given aircraft may use different displays forming images at differing distances from the user's eye. The optical system
16
for the HUD system
10
in the simulator
19
is a function of both the screen placement and the HUD type used in the simulator
19
. A different optical system
16
must therefore be designed for each HUD type used with each different display having a different screen distance from the eye. Further, as refocusing requirements become shorter and shorter, to match decreased distances in the simulator's OTW display, it becomes more and more difficult to refocus the HUD optics while maintaining the actual HUDs FOV, vignetting characteristics, and mechanical packaging.
A technique to avoid this problem is to project the HUD symbology on the same screen on which the OTW scene is projected, as shown the simulator
19
′ of FIG.
3
. Both the OTW projector
24
, which projects the OTW scene, and a HUD projector
30
, which projects the HUD symbology, appear on the same screen
28
, and consequently, the OTW scene and the symbology are physically co-located.
However, referring again to
FIG. 1
, in an actual cockpit environment, the HUD system
10
provides the symbology on only a limited portion of the field of view available to the pilot. If the pilot moves his head around in an actual cockpit as in
FIG. 1
, portions or all of the symbology may or may not be visible to the pilot due to optical limitations of the HUD system, herein described as occulting or vignetting. The term “occulting” is meant to broadly describe any blocking or interruption in the visibility of the symbology, such as by structures of the cockpit or in the HUD optical system. The term “vignetting” refers to a type of occulting which is caused by movement of the viewer's eye beyond the optically functional portions of the lens system which is normally in the center of the lens or lenses. The occulting or vignetting is caused by a combination of things in the HUD optical system
10
, i.e., the beamsplitter
18
, the lenses and lens frames of the optics, and the CRT. For example, if the pilot's head is moved so that some of the HUD FOV falls outside of the beamsplitter coverage
18
, that portion is no longer viewable by the pilot.
Consequently, in the arrangement shown in
FIG. 3
, while projection of the HUD generated symbology and the OTW scene onto a common screen
28
produces the desired co-location effect, the system does not simulate the vignetting or occulting characteristics associated with the real HUD being simulated. The prior art therefore fails to provide a realistic simulation of a vehicle heads up display.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved head-up simulator that better simulates the real HUD system in an economical way.
In accordance with the present invention, a vehicle simulator is provided which includes a projection system for projecting a generated scene and symbology onto a common viewing screen. Tracking apparatus is provided for producing position and/or angular orientation signals representative of the position of the eye of a person viewing the projected scene and symbology on the common viewing screen. An image generation system is included for generating the scene and symbology for the projection system, the symbology being generated as a function of the position and/or angular orientation signals provided by the tracking apparatus.
The OTW scene and the symbology are projected onto a common screen and thus are co-located, while the image generator, using data indicative of the position of an eye of the person in the simulator, produces the symbology in a way which simulates the vignetting or occulting effect characteristic of the HUD optical type being simulated.
Other features of the invention will become more readily apparent from the detailed description, and the scope of the invention will be described by the claims.
REFERENCES:
patent: 3936148 (1976-02-01), Ellis
patent: 4652870 (1987-03-01), Steward
patent: 5072218 (1991-12-01), Spero et al.
patent: 5320534 (1994-06-01), Thomas
patent: 5430505 (1995-07-01), Katz
patent: 5838262 (1998-11-01), Kershner et al.
patent: 6014117 (2000-01-01), Hennessy et al.
Hegg Ronald G.
Turner James A.
Awad Amr
L-3 Communications Corporation
Saras Steven
Tiajoloff Andrew L.
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