Computer graphics processing and selective visual display system – Image superposition by optical means – Operator body-mounted heads-up display
Reexamination Certificate
1999-01-28
2001-06-12
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Image superposition by optical means
Operator body-mounted heads-up display
C359S013000, C359S630000
Reexamination Certificate
active
06246383
ABSTRACT:
FIELD OF THE INVENTION
1. Background of the Invention
The invention relates to a head-mounted display comprising an image display system which is common for two separate light channels, and an optical system for projecting an image formed in the image display system in a right and a left exit pupil of the head-mounted display via a first and a second light channel, each light channel comprising imaging optics, the optical system comprising a first hollow mirror and a beam splitter being arranged between the image display system and the first hollow mirror.
2. Description of the Related Art
A head-mounted display of the type described in the opening paragraph is known from International Patent Application WO 96/05532, corresponding to U.S. Pat. No. 5,739,955. In this head-mounted device, a liquid crystalline image display panel is imaged on a left and right exit pupil of the head-mounted display by means of a field lens, a hollow mirror and two crossed reflecting surfaces via two light channels each comprising a folding mirror and an eyepiece consisting of three lenses. The exit pupils of the head-mounted display are assumed to coincide with the user's pupils. The image is ultimately imaged on the retina of both eyes of the user.
A drawback of the head-mounted display described in this application is that the large number of lenses and mirrors render the design relatively expensive. Instead of glass, inexpensive material such as, for example, synthetic resin material may be used. However, this has the drawback that the image realized thereby has a considerably poorer quality.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a head-mounted display having a relatively simple design, a low cost and a light weight.
To this end, the head-mounted display according to the invention is characterized in that the imaging optics of the first light channel comprise a second hollow mirror and a first splitting mirror, and the imaging optics of the second light channel comprise a third hollow mirror and a second splitting mirror, a lens being arranged between the image display system and the beam splitter.
The function of a three-lens eyepiece is herein ensured by the combination of a hollow mirror and a splitting mirror. It is further proposed to arrange a lens between the image display panel and the beam splitter in order to optimize the image quality. This lens is common for the two light channels. The assembly of the head-mounted display proposed is relatively simple. Moreover, the number of optical components is reduced. The field lens may also be dispensed with. The head-mounted display will thus have a considerably lighter weight.
Another embodiment of the head-mounted display according to the invention is characterized in that the imaging optics of the first light channel comprise a second hollow mirror and a first splitting mirror, and the imaging optics of the second light channel comprise a third hollow mirror and a second splitting mirror, a folding mirror being arranged between the splitting mirror and the hollow mirror in each light channel.
Instead of the lens in the common light path, a folding mirror is arranged in each light channel so as to optimize the image quality.
A preferred embodiment of the head-mounted display according to the invention is characterized in that the first splitting mirror of the beam splitter and the first splitting mirror of the first light channel have a given mutual position, and the second splitting mirror of the beam splitter and the second splitting mirror of the second light channel have a given mutual position, the splitting mirrors being rotatable about their own point of rotation, such that said positions are maintained.
The first splitting mirror of the beam splitter may enclose a given angle with the first splitting mirror of the light channel, for example, the first light channel into which the image is sent by the first splitting mirror of the beam splitter. The second splitting mirror of the beam splitter may enclose a given angle with the second splitting mirror of the light channel, for example, the second light channel into which the image is sent by the second splitting mirror of the beam splitter. The angle which they enclose may be, for example, 90°. In this configuration, the image display system is present between the light channels and the hollow mirror is present on the opposite side of the beam splitter. The first splitting mirror of the beam splitter and the first splitting mirror of the first light channel, on the one hand, and the second splitting mirror of the beam splitter and the second splitting mirror of the second light channel, on the other hand, may be, for example, parallel to each other. In this case, the hollow mirror is present between the light channels, and the image display system is present on the opposite side of the beam splitter.
By rotating the splitting mirrors about their own axis and maintaining the mutual position, as described above, of the splitting mirrors of the beam splitter in the light channels, the interpupilar distance (IPD) can be adapted to the user.
A further embodiment of the head-mounted display according to the invention is characterized in that the image display system comprises a reflective image display panel, in that the first hollow mirror is at least semitransparent, with an illumination system being present on the side of the first hollow mirror remote from the image display panel, and in that the illumination system and light channel comprise a polarizer, the polarizer of the illumination system being crossed with respect to the polarizers in the light channels.
An advantage of the use of a reflective image display panel is that the “blind” space between the pixels is much smaller than in a transmissive image display panel. This has the result that the pixels are stacked much more densely so that the required surface area for the same number of pixels is much smaller as compared with a transmissive image display panel. Consequently, the image display panel will be much less expensive.
A further embodiment of the head-mounted display according to the invention is characterized in that at least a number of curved optical surfaces of the head-mounted display are aspherical.
Imaging errors such as coma, astigmatism and curvature of the image field are considerably reduced thereby.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 3867633 (1975-02-01), Patrick et al.
patent: 4530602 (1985-07-01), Pomphrey, Jr.
patent: 5035474 (1991-07-01), Moss et al.
patent: 5579026 (1996-11-01), Tabata
patent: 5659430 (1997-08-01), Togino
patent: 5706137 (1998-01-01), Kelly
patent: 5714967 (1998-02-01), Okamura et al.
patent: 5739955 (1998-04-01), Marshall
patent: 5764363 (1998-06-01), Ooki et al.
patent: 5801885 (1998-09-01), Togino
patent: 5982343 (1999-11-01), Iba et al.
patent: 6023253 (2000-02-01), Taniguchi et al.
patent: 96/05532 (1996-02-01), None
Goodman Edward W.
Osorio Ricardo
Shalwala Bipin
U.S. Philips Corporation
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