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MONITOR FOR SHOWING HIGH-
RESOLUTION AND THREE-DIMENSIONAL
IMAGES AND METHOD
Priority of Provisional U.S. Patent Application No. 60/142,752, filed Jul. 8, 1999, is claimed under 35 USC 119(e).
Presently three-dimensional displays are based either on imaging techniques which give rise to an apparent stereo by perspective views or on two images being presented which are separated such that the right eye and left eye see their respective images which are distinguished or differentiated by polarization characteristics of light. Most of these displays are single purpose in that they are designed for the purpose of viewing stereo. Two images separated or distinguished by polarization can either be superimposed as they are with two movie projectors or they may be displayed time sequentially to give an image which appears to be continuous.
The current stereo display techniques are confined to using field sequential techniques which either require very fast video switching thus needing a very rapid display or require two small displays worn in a headset. The field sequential methods or techniques are prone to flicker as the two images are superimposed upon each other in time sequence. Part of the flicker problem is the very high contrast between the right and left image, e.g., the right image is expected to be viewed by the right eye of a person viewing the image (viewer) and the left image is expected to be viewed by the left eye, while those images are being presented which makes them flicker even at higher than normal frame rates. Also, a consequence is a reduction in bandwidth capability since the two images presented are normally in a standard bandwidth for two dimensions.
To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described in the specification and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but several of the various ways in which the principles of the invention may be suitably employed.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
Although the invention is shown and described with respect to one or more embodiments, it is to be understood that equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS In the annexed drawings:
FIG. 1 is a schematic illustration of a monitor for showing high-resolution and three-dimensional images using plane polarized light in accordance with the invention and of a viewer viewing such images;
FIG. 2 is a schematic illustration of a monitor for showing high-resolution and three-dimensional images using circularly polarized light in accordance with the invention and of a viewer viewing such images; 5 FIG. 3 is a schematic illustration of another embodiment of a monitor for showing high-resolution and threedimensional images using circularly polarized light in accordance with the invention and of a viewer viewing such images;
10 FIG. 4 is a schematic illustration of an embodiment of monitor of the invention in folded condition;
FIG. 5 is a schematic illustration of the embodiment of monitor of the invention of FIG. 4, here shown in partly s open condition;
FIG. 6 is a schematic illustration of the embodiment of monitor of the invention of FIGS. 4 and 5, here shown in fully open condition;
FIG. 7 is a schematic illustration of a display system 20 according to an embodiment of the invention;
FIGS. 8A, 8B and 8C are schematic illustrations of an embodiment of the invention illustrating the reversal or inversion of images one of the respective displays in the monitor of the invention; and 25 FIG. 9 is a schematic illustration of a display system according to an embodiment of the invention.
30 This invention includes two flat panel displays which are arranged at an angle relative to each other, for example, at 90 degrees or approximately 90 degrees and a beam splitter which is positioned at the bisectrix between the two displays. As an example of a bisectrix, consider two flat panel
35 displays, the planes of which are parallel with the same linear axis; thus, for example, the two planes may be arranged similar to the front and back covers of a book, with the spine of the book representing the axis. The bisectrix would be an angle that bisects the angular relation of the two
4q planes (displays or book covers); and, more preferably, the bisectrix would be a plane that also is parallel to the linear axis (e.g., like the book spine) and bisects the angle equally between the first two mentioned planes (e.g., the displays). As is described further below the images from both displays
45 may be viewed; and if the images provided thereby are, respectively, left and right eye images, which can be discriminated, e.g., by polarized lenses or some other means, a stereoscopic (3D) display is obtained.
If the flat panel displays are liquid crystal displays, the
50 light output of each display will be polarized. The usual polarization direction for many active matrix displays, for example, is at 45 degrees to the edge of the display. This characteristic of such liquid crystal displays allows the present invention to be carried out with relative efficiency
55 and minimum parts.
When linear polarized light is reflected from a surface that is in a plane which is perpendicular or transverse to the direction of incident light, it does so without a change in direction of polarization. However, if the reflecting surface
60 (in this case the beam splitter) is set at an angle to the surface of one of the liquid crystal displays such that the reflected image changes direction by 90 degrees or approximately 90 degrees and the direction of polarization is at 45 degrees to the change of direction, the result will be that the linear
65 polarized light will appear to have rotated 90 degrees. As an example, consider two adjacent flat panel displays, each in a vertical plane, the two meeting at and including a common
linear axis and being oriented so the displays are at 90 degrees relative to each other, and each display providing a light output that is polarized in the same direction, e.g., from the lower left toward the upper right of the respective display, say at an angle of 45 degrees relative to horizontal or vertical (not considering sign). The beam splitter is oriented between the displays, has its plane (or an extension thereof) intersecting the linear axis mentioned, and is at an angle of 45 degrees relative to each display; and the beam splitter is so positioned relative to the two displays that one can be viewed directly through the beam splitter and the other can be viewed by reflected light from the beam splitter to provide a virtual image of the latter display.
If the two displays are positioned with respect to the beam splitter such that the virtual image of one display is exactly superimposed on the other, the beam splitter will reflect the angle of the polarization vector at right angles to the display which is not reflected. Consider as an example the polarization direction of light incident on the beam splitter intended for reflection to be represented by an arrow pointing in the direction of polarization; the reflected light from the beam splitter will present the mirror image of the arrow, and, therefore, the arrow will appear to a viewer to be at 90 degrees (crossed) relative to the original polarization of the incident light on the beam splitter (and, thus, also crossed relative to the polarization direction of light transmitted directly through the beam splitter from the other display). Therefore, the reflected image from the beam splitter and the direct image viewed through the beam splitter have linear polarization directions that are at right angles; and this can be accomplished without additional elements.
If an electronic signal is received corresponding to the left and right image they can be displayed separately on the two liquid crystal display panels. They can be seen by the left and right eye in the proper order by using glasses which are linearly polarized at right angles to each other and parallel to the image that is intended for the left or right eye.
Although the invention is described using Liquid crystal displays (LCDs), it will be appreciated that the invention may use other displays or image generators, provided the light output from the displays is polarized or is given polarization characteristics, e.g., by using one or more polarizers in the light path. For convenience of description and to avoid adding unnecessary verbiage, the image generators or displays are considered and described herein as active matrix LCDs, but it will be appreciated that other displays or image generators may be used.
It may be desirable at times to use circular polarized light to separate the two images mentioned above. This can be done in several ways, two of which are mentioned here by way of example. The first is by putting quarter wave plates at both image generators, such as the LCDs, with their slow axis horizontal or vertical on each of the LCDs. More generally, the slow axis of the quarter wave plates is at 45 degrees to the polarization direction of linear polarized light from the respective LCDs. This continues to maintain the same structure on both displays. When the circular polarized light is reflected from the beam splitter it reverses its sense; thus, right circular polarization becomes left circular polarization. A second way of achieving two circular polarizations is to place a quarter wave plate at the exit bezel or a location optically downstream of the two LCDs so that both the direct view image and the virtual image light go through the quarter wave plate and become circularly polarized. Thus, the slow axis is at 45 degrees to the two polarizations which were generated and provided by reflection or transmission at the beam splitter.
Circular polarizers are generally produced by bonding a quarter wave plate to a linear polarizer such that the linear polarizer is toward the observer. The quarter wave plate converts right-handed circular polarized light to linear polar
5 ized light, and it converts left-handed circular polarized light to linear polarized light, except the polarization directions of the two linear polarized lights are at right angles to each other. Since most circular polarizers which use quarter wave plates are tuned for green light, they are not perfect. In order to achieve a higher performance the circular polarizer may be mounted so that the polarized direction of the linear polarizer at the output is perpendicular to the linear polarization at the display for the nullification of the transmitted image. For the reflected image the direction should be s parallel for the linear polarization at the polarizer and display respectively.
The information is presented to the displays of the invention such that the information in one display is a mirror image so that its reflection from the beam splitter is a normal
2Q image. This is normally done electronically but it can be accomplished by how the video signal is brought into the flat panel display. For displays that are mounted vertically the reflected display can be scanned from right to left instead of left to right. Depending upon the signal the video signal can
25 be reversed either line at a time or frame at a time.
The invention has additional useful features. By displaying normal video images which are field sequential one field can be displayed on one display and the other field on another, thus allowing a signal from both fields to be present
30 at one time. This arrangement reduces motion artifacts since both fields are simultaneously displayed. The liquid crystal display continuously holds the image until it is changed. This also makes possible the display of HDTV images which are based on field sequential at half the bandwidth in each
35 display. A further advantage in this form of mixing is an improvement in the color separation. The color in many flat panel displays is based on vertical lines of red, green, blue and white. When they are reflected they go from white blue green and red thus giving a different order to the colors in
40 reflection. This reduces color borders and other artifacts caused by the color sequence above.
The present invention has the ability to display images in three dimensions and also has the ability to improve the resolution and color artifacts of flat panel monitors.
45 Referring to the drawings wherein like reference numerals designate like parts in the several figures, and initially to FIG. 1, a monitor for showing high-resolution and threedimensional images is generally illustrated at 10 being viewed by an individual 11 as a viewer of images provided
50 or shown by the monitor. The monitor 10 includes a pair of liquid crystal displays 12a, 12b and a pair of linear polarizers 13a, 13b. The displays 12a, 12b may have integral polarizers, as in active matrix displays, in which case separate polarizers 13a, 13fc would be unnecessary. The
55 displays 12a, 12b and polarizers 13a, 13fc provide linear polarized light images to a beam splitter 14 of the monitor 10. The image from the display 12a and polarizer 13a is viewed directly by the viewer 11 as light therefrom is transmitted directly through the beam splitter 14. The image
60 from the display 12b and polarizer 13fc is reflected by the beam splitter toward the viewer 11; the direction of polarization of the linear polarized light provided from the display 12b and polarizer 13fc is rotated 90 degrees due to the mirror image effect described above so that the light 15
65 reaching the viewer 11 includes two images, one from each display 12a, 12b and the polarization directions of the linear polarized light representing such images are crossed, e.g., at
90 degrees to each other, as was described above. The viewer 11 uses linear (plane) polarizers 16a, 16b to view by his or her eyes 17a, 17b the left and right eye images from the monitor 10. The polarizer 16a, for example, transmits linear polarized light from a respective display, e.g., display 5 12a, which is intended to be viewed by the left eye of the viewer; and the polarizer 16b, for example, transmits linear polarized light from the other display, e.g, display 12b, providing the right eye image to the right eye of the viewer 11. The beam splitter 14 is shown as a prism beam splitter, but it will be appreciated that other types of beam splitters may be used; many are well known in the art.
It will be appreciated that the monitor 10 of FIG. 1 has its parts arranged as was described above. For example, the displays 12a, 12b may be flat panel displays which are arranged in a vertical, horizontal, or some other common direction, and the planes thereof are parallel with an imaginary linear axis 18 which extends in a direction perpendicular to the plane of the drawing relative to the illustration of FIG. 1. Also, the eyes of the viewer 11 are shown somewhat 2Q in perspective relative to the drawing, as they typically would be aligned in parallel with the axis 18 for optimum viewing, although some off-axis alignment may be acceptable.
An image signal source 19 is illustrated. Such source may 25 be a video source, a computer, a tape player or CD Rom player, etc. The image signal source may be remote and the image signal may be provided via a network or the like. The image signal source provides signals to the displays 12a, 12b as a usual video circuit or video card provides signals to a 30 display to create images for viewing. If desired, the image signal source 19 may include circuitry for reversing the direction of scanning or reversing the image being provided to a respective display, as was mentioned above.
Turning to FIG. 2, another monitor for showing high- 35 resolution and three-dimensional images is illustrated generally at 20. The monitor 20 is similar to the monitor 10, except the monitor 20 uses circular polarized light. Accordingly, respective quarter wave plates 21a, 21b are provided to convert linear polarized light from the respective 40 displays 12a, 12b and, if used, linear polarizers 13a, 13b, to circular polarized light. The light output 15' may include both left and right circular polarized light, and the circular polarizers 16a', 16b' respectively transmit one or the other of such left or right circular polarized light to respective eyes 45 17a, 17b of the viewer 11 for viewing respective left and right eye images. Although the direction of circular polarization of light incident on the beam splitter from the two displays 12a, 12b may be the same, the beam splitter reverses the direction of circular polarization of the light it 50 reflects from the display 12b, as was described above. The circular polarizers 16a', 16b' can distinguish or discriminate between the left and right circular polarized light to provide 15 respective images to the eyes 17a, 17b of the viewer 11.
Referring briefly to FIG. 3, another monitor for showing 55 high-resolution and three-dimensional images is illustrated generally at 30. The monitor 30 is similar to the monitor 20, except the monitor 30 uses only one quarter wave plate 21' to obtain both left and right circular polarized light from the respective linear polarized light inputs thereto from the 60 displays 12a, 12b, linear polarizers 13a, 13fc (if used), and beam splitter 14. The quarter wave plate is arranged relative to the polarizers 13a, 13fc or the direction of linear polarized light so the slow axis is at 45 degrees relative to the direction or plane of such linear polarization. 65
Turning to FIGS. 4, 5 and 6 a packaged monitor for showing high-resolution and three-dimensional images and,
alternatively, for showing multiple images in parallel, is shown generally at 40. In FIG. 4 the monitor 40 is in closed condition; in FIG. 5 the monitor 40 is in partly open condition; and in FIG. 6 the monitor 40 is in full open condition. The monitor 40 includes a hinge 41 relative to which the displays 12a, 12b, linear polarizers 13a, 13fc, and beam splitter 14 are mounted. In FIG. 4 those components are pivoted on or relative to the hinge 41 and to each other to assume a relative compact nested arrangement, e.g., for storage in a minimum space. A protective cover or package 42, including cover portions 42a, 42b, possibly hinged at 41', as is illustrated in FIG. 4, may be placed over those components to avoid damage while in stored condition. Connections 19' may be provided to couple the displays to an image signal source or, if desired, the image signal source may be appropriately mounted in the package 42.
As is illustrated in FIG. 5, the monitor 40 includes the displays 12a, 12b, linear polarizers 13a, 13fc (and quarter wave plates, if used), and beam splitter 14 arranged in partially open condition relative to the stored condition; this partially open condition is obtained by rotation or pivoting relative to the hinge 41. If desired appropriate stops may be used to help align the components relative to each other in orientation similar to that described above with respect to FIGS. 1-3.
As is illustrated in FIG. 6, the monitor 40 includes the displays 12a, 12b, linear polarizers 13a, 13fc (and quarter wave plates, if used), and beam splitter 14 arranged in fully open condition relative to the stored condition; this fully open condition has the displays 12a, 12b oriented in adjacent parallel relation so both can be viewed side by side to present increased amount of information to the viewer. Such orientation is obtained by rotation or pivoting relative to the hinge 41. If desired appropriate stops may be used to help align the components relative to each other as illustrated in FIG. 6.
Thus, it will be appreciated that the monitor 40 may be used to provide either stereo views or large area mono views of respective images. Furthermore, the invention provides a device for not only displaying three dimensions but also improving the resolution and color artifacts of flat panel monitors.
The various methods of using the invention are described above. Summarizing, though, it will be appreciated that using the invention, e.g., as illustrated in FIGS. 1-3 and 5, two images are provided and can be discriminated by polarization characteristics to obtain respective images for viewing. The two images may be provided simultaneously without the need to provide frame or field sequential images or time sequential images (e.g., one image for viewing by one eye and the next image or viewing by the other eye, and so forth); thus, increased resolution and reduction of flicker can be obtained. Further, if desired, using the invention as illustrated in FIG. 6, large area display may be obtained by displaying respective images on adjacent displays 12a, 12b, for example.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, equivalent alterations and modifications will occur to others skilled in the art upon reading and understanding this specification and the annexed drawings. In particular regard to the various functions performed by the above described integers (components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such integers are intended to correspond, unless otherwise indicated, to any integer which