Computer graphics processing and selective visual display system – Image superposition by optical means – Operator body-mounted heads-up display
Patent
1995-02-02
2000-10-31
Mengistu, Amare
Computer graphics processing and selective visual display system
Image superposition by optical means
Operator body-mounted heads-up display
359630, G09G 106
Patent
active
061409804
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Head mounted display systems have been developed for a number of different applications including use by aircraft pilots and for simulation. Head mounted displays are generally limited by their resolution and by their size and weight. Existing displays have relatively low resolution and are positioned at a relatively large distance from the eye. Of particular importance, is to keep the center of gravity of the display from extending upward and forward from the center of gravity of the head and neck of the wearer, where it will place a large torque on the wearer's neck and may bump into other instruments during use. There is a continuing need to present images to the wearer of a helmet mounted display in a high-resolution format similar to that of a computer monitor. The display needs to be as non-intrusive as possible, leading to the need for a lightweight and compact system.
Head mounted displays can also utilize eye tracking systems in flight control, flight simulation and virtual imaging displays. Eye control systems generate information based on the position of the eye with respect to an image on a display. This information is useful for a variety of applications. It can be used to enable the viewer to control "hands-free" movement of a cursor, such as a cross-hair on the display.
Apparatus for detecting the orientation of the eye or determining its line-of-sight (LOS) are called occulometers or eye trackers and are well known in the art. (See for example U.S. Pat. Nos. 4,109,145, 4,034,401 and 4,028,725).
SUMMARY OF THE INVENTION
In accordance with the present invention a head mounted display is preferably either an electroluminescent (EL) or an active matrix liquid crystal display (AMLCD) comprising thin film transistor (TFT) driving elements formed of single crystal silicon and then transferred to a transparent glass substrate. Each TFT circuit is connected to an electrode which defines a picture element (pixel) of the display. The head mounted display system can also include a detector array comprising thin film integrated optical diode detectors is formed of III-V materials and transferred directly onto a flat panel active matrix display.
In a preferred embodiment of a direct view eye tracking dispaly, the detectors are positioned such that each is completely above the drive transistors of the active matrix circuit i.e., adjacent to the pixel area and therefore do not block any of the display's light output. The light output from the display, either infrared or visible, is used to determine the position of the eye. No additional optics, such as, fiber optics to/from remote displays are required in this approach. The chief advantage is that the integrated eyetracker/display can be inserted in a helmet-mounted optical system without physical modification to the helmet or optics. This advantage results from the fundamental reciprocity of the axial light rays that are used to determine the eye position. An axial ray, is a light ray that emanates from the display and travels through the optical axis of the eye, normal to the retina. These rays, when reflected by the retina, can travel back to the display along the same optical path (in accordance with the optical reciprocity theorem). Except for divergence of the rays, the reflected rays return to the vicinity of the emitting pixel. In this way, the detector can identify the area of the display that is sighted by the user. Software in a computer then provides a cursor at this location.
In another alternative embodiment, instead of using the visible scene from the display, some of the frames in the display are used for brief presentation of an interlaced eyetracker pattern. If the repetition rate of the test pattern is sufficiently infrequent, the user (viewer) will not perceive its presence. This pattern can consist of a single pixel being illuminated or can have some other geometric pattern. Light from a single lit pixel enters the eye through the pupil and is reflected from the retina. The path of the reflected light c
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Gale Ronald
Jacobsen Jeffrey
Spitzer Mark B.
Kopin Corporation
Mengistu Amare
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