Optical: systems and elements – Single channel simultaneously to or from plural channels – By partial reflection at beam splitting or combining surface
Reexamination Certificate
1999-11-10
2001-04-24
Epps, Georgia (Department: 2873)
Optical: systems and elements
Single channel simultaneously to or from plural channels
By partial reflection at beam splitting or combining surface
63, 63
Reexamination Certificate
active
06222677
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to compact optical systems and, more particularly, to compact optical systems for use in display devices, for example, personal devices such as wearable personal computer systems, head mounted displays, portable telephones and the like.
BACKGROUND OF THE INVENTION
Virtual image displays combine magnifying optics with a small image panel to provide the viewer with a virtual image capable of displaying large amounts of information. Such displays have found application in so called head mounted displays and are used in conjunction with a computer-based device for a variety of applications. As is known, the computer-based device includes processing and display driver circuitry for generating the image signal to be displayed via the optics and image panel.
However, such conventional virtual image displays are known to have many shortcomings. For example, such displays have suffered from being too heavy for comfortable use, as well as too large so as to be obtrusive, distracting, and even disorienting. These defects stem from, among other things, the incorporation of relatively large optics systems within the mounting structures, as well as physical designs which fail to adequately take into account such important human factors as size, shape, weight, etc.
Examples of some conventional head mounted virtual displays are shown in
FIGS. 1 and 2
.
FIG. 1
illustrates a head mounted virtual display unit
10
which rests on the users head and face in a manner similar to that of a pair of eye glasses. The user views virtual images through the display portion
12
. Nose bridge
14
and side supports
16
serve to provide support for the display while on the users head and face. The unit
10
may be connected to a computer via connector
18
. It is known that such a unit is cumbersome and permits the wearer to see substantially nothing other than the display screen. That is, the user is unable to view his immediate environment. Such a head mounted virtual display is disclosed in an international patent application identified as WO 95/11473, the disclosure of which is incorporated herein by reference.
FIG. 2
illustrates a head mounted monocular virtual display unit
20
. The support structure
12
is positioned on a users head and the display portion
14
comes down in the users field of vision. This design is also known to be cumbersome and likely to obstruct the users surrounding view. Such a head mounted monocular virtual display is also disclosed in a the international patent application identified as WO 95/11473.
Other examples of conventional compact display systems and head mounted displays are disclosed in U.S. Pat. No. 5,771,124 to Kintz et al., U.S. Pat. No. 5,757,339 to Williams et al., and U.S. Pat. No. 5,844,656 to Ronzani et al., the disclosures of which are incorporated herein by reference. Still further, it is known that Sony Corporation makes a head mounted virtual display known as the “Glasstron.”
However, all of the examples given suffer from one or more of the above-mentioned design deficiencies. As a result, such deficiencies have seriously hindered the general acceptance of such devices.
Accordingly, there is a need for a compact optical system for use in display devices, for example, personal devices such as wearable personal computers, head mounted displays, portable telephones and the like, which substantially reduces or eliminates these and other deficiencies.
SUMMARY OF THE INVENTION
The present invention provides various optical system designs for use in display devices such as, for example, a head mounted virtual image display, that remedy defects exhibited by conventional designs, e.g., prohibitive size and weight, obstructed view, etc. The optical system is very compact and light weight so that, combined with a head mounted support structure to hold the display in proximity to the eye, a weight on the order of only 1 to 2 ounces may be achieved. Such a display is achieved with excellent optical properties. One particular advantageous feature of the invention is that a given field of view may be obtained with a relatively small thickness associated with the optical system, resulting in light weight and small volume. Combined with a light weight computer-based device, this display device makes possible a uniquely portable and convenient wearable computing system.
In one aspect of the invention, a compact optical system for directing an image signal for viewing by a user, the image signal being generated in accordance with a microdisplay, comprises: (i) a first prism positioned proximate to the microdisplay; (ii) a quarter wave plate positioned proximate to the first prism; (iii) a reflective lens positioned proximate to the quarter wave plate; and (iv) a second prism positioned proximate to the first prism; wherein the first prism, the quarter wave plate, the reflective lens, and the second prism are arranged such that the image signal enters the first prism, reflects at an air gap between the first prism and the quarter wave plate, reflects at a boundary between the first prism and the second prism, passes through the quarter wave plate a first time, reflects at the reflective lens, passes through the quarter wave plate a second time, passes through the boundary between the first prism and the second prism, and exits the second prism for viewing by the user.
Preferably, the boundary between the first prism and the second prism is configured to reflect polarized light associated with the image signal generated by the microdisplay. For example, the boundary may include a multilayer reflective coating or a DBEF film. Further, the reflective lens preferably includes a convex-shaped surface facing the quarter wave plate. The reflective lens may include a reflective coating such as, for example, a fully reflecting metallic coating, a fully reflecting multilayer dielectric coating, a partially reflecting coating, or a holographic coating. Still further, the reflective coating preferably has a predetermined wavelength associated therewith for permitting substantial reflection of the image signal and substantial transmission of one or more other images, e.g., such as images on the other side of the reflective lens, that is, the side opposite the side facing the user. In this manner, the user may view the image signal but substantially see-through the optical system to the surrounding environment.
Various alternative embodiments of the invention are provided for use in accordance with transmissive, emissive, and/or reflective type microdisplays.
In another aspect of the invention, a head mounted virtual image display unit comprises: (a) a microdisplay; (b) an optical system for directing an image signal for viewing by a user, the image signal being generated in accordance with the microdisplay, the optical system including: (i) a first prism positioned proximate to the microdisplay; (ii) a quarter wave plate positioned proximate to the first prism; (iii) a reflective lens positioned proximate to the quarter wave plate; and (iv) a second prism positioned proximate to the first prism, wherein the first prism, the quarter wave plate, the reflective lens, and the second prism are arranged such that the image signal enters the first prism, reflects at an air gap between the first prism and the quarter wave plate, reflects at a boundary between the first prism and the second prism, passes through the quarter wave plate a first time, reflects at the reflective lens, passes through the quarter wave plate a second time, passes through the boundary between the first prism and the second prism, and exits the second prism for viewing by the user; and (c) an optical system mounting structure for supporting the optical system within the field of view of an eye of the user. Preferably, the mounting structure is configured to permit the optical system to be selectively moved into and out of the field of view of the eye of the user.
In yet another aspect of the invention, a portable computer system comprises: (1) a head mou
Budd Russell A.
Dove Derek B.
Epps Georgia
Ichii Yoshihiro
International Business Machines - Corporation
Ryan & Mason & Lewis, LLP
Seyrafi Saeed
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