GB2308677A

GB2308677A - Polarised stereoscopic display apparatus and glasses

Info

Publication number: GB2308677A
Application number: GB9526611A
Authority: GB
Inventors: Yoshiharu Chikazawa
Original assignee: Thomson Multimedia SA
Current assignee: Technicolor SA
Priority date: 1995-12-28
Filing date: 1995-12-28
Publication date: 1997-07-02
Also published as: GB9526611D0

Description

Stereoscopic display apparatus and stereoscopic display glasses The present invention relates to a stereoscopic display apparatus and to stereoscopic display glasses usable with such an apparatus, in particular to a stereoscopic display wherein a left image and a right image are displayed independently and simultaneously and which can be viewed with the aid of special stereoscopic display glasses, so that a viewer has the impression of a stereoscopic image.

The following main stereoscopic display systems (3D displays) using special glasses are known already: i) One known system is a time sharing stereo-image method using polarizing glasses, wherein left and right images are displayed framesequentially or field-sequentially according to the display used, which means that the images change frame by frame or field by field. A Pi-cell in front of the display changes the polarization direction simultaneously with the changing of left and right images. The observer wears the glasses, which have perpendicular polarizing filters. Therefore the left eye can see only left images and the right eye can see only right images. Such a system is produced for example by Tektronics, Inc.

ii) There is further known a two-projector method using polarizing glasses wherein two projectors project left and right images essentially onto the same area of a screen. The projection of the two pictures may be done with time-multiplex method or concurrently. These projectors have perpendicular polarizing filters and because of the polarizing filters, the polarization direction of the left and right images are perpendicular. The observer wears glasses that have perpendicular polarizing filters. Therefore his left eye only sees left images, wherein his right eye only sees right images. Such systems are produces and sold for example by Ikegami, Sanyo and Toshiba.

iii) There exists also another two-projector-method using circular polarizers. A first polarizer, e.g. for the left eye-image, is clockwise circular and a second polarizer, e.g. for the right eye-image, is counter-clockwise circular. The user has to wear according glasses having also polarizers, which are, according to this example, clockwise polarising for the left eye and counter-clockwise polarizing for the right eye.

vi) There is further known a time sharing stereo image method using shutter goggles, wherein left and right images are displayed framesequencially or field-sequencially on a display and the observer wears a shutter goggle, that closes left and right shutters synchronous with left and right images on the display. Therefore the left eye only sees a left image, whereas the right eye only sees a right image. Such systems are produced for example by Sanyo and Sony.

v) Further a micropolarizer method is known, wherein micropolarizers are set on a display either line by line or pixel by pixel.

Then left and right images are mixed linewise or pixelwise according to a suitable arrangement of the polarizers. The observer wears glasses that have perpendicular polarizing filters, so that the right eye only sees a right image, wherein the left eye only sees a left image. Such a method is described in e.g. U.S. patent 5,264,964. Such a system is sold by a company named Vrex.

All these prior art stereoscopic images systems using special glasses or an optical lens adapter have the disadvantage that in case the special glasses are not used, it is not possible to see a normal planar image, because ghost images will appear in the normal image.

There is also known from the article "HDTV single camera 3D system and its aplication in mikrosurgery", Mochizuki et al; SPIE Vol.2177, pages 31-34, a stereoscopic display system used in the field of microsurgery, wherein a threedimensional high definition television system suitable for attachment to a stereoscopic operating microscope allowing 3D medical documentation is used. The system is a HDTV single camera 3D system wherein an optical lens adaptor is attached to the camera and an optical adaptor is attached to a monitor. The optical lens adapter deflects the images and two images, one for the right eye and the other for the left eye, are projected on the monitor. Through the optical adapter attached to the monitor, each eye picks up the right and left image, respectively.This known three-dimensional system is suitable for attachment to a stereoscopic operating microscope.

It is the object of the present invention to provide a stereoscopic display apparatus and stereoscopic display glasses usable with such a stereoscopic display system, wherein a viewer can see a stereoscopic image when using the apparatus and the special glasses, but where in addition, the viewer can see a normal image when he is not wearing the special glasses.

This object is solved by the subject matter of the independend claims. Advantageous embodiments are given by the subclaims.

The present invention relates to a stereoscopic display apparatus having display means for displaying essentially simultaneously a left image and a right image on different areas of a screen, and having first polarizer means such that the left and right image are displayed with different polarizations.

The present invention is also related to a special kind of glasses comprising light-deflection means, like e.g. prisms, mirrors or thelike, for conducting light-rays from a first direction to the left eye and from a second direction to the right eye of a viewer. Said glasses include in addition second polarizer means with different polarizing directions for the left eye and for the right eye, which may correspond to the polarization of the images, generated by the stereoscopic display apparatus.

The system operation is as follows: The first polarizer means of the display apparatus includes perpendicular polarizers which are provided between the display means and a viewer, so said polarizers may be set e.g.

on the display or the respective displays. Then the polarizing direction of the image for the right eye is parallel to the right polarizer of the second polarizer means of the glasses. Similarly the polarizing direction of the image for the left eye is parallel to the left polarizer of the special glasses.

By the deflection means of the special glasses, eyes can only see left and right images with small eye convergence. By the appropriate choice of polarizers of images and glasses, right eye only sees right images on "the display for right eye", whereas the left eye only sees left images on "the display for left eye". Therefore the observer sees stereoscopic images by the binocular parallax effect.

Observers without special glasses can see normal (2D) images on each of the display areas, which means either on the area for the left image display or on the area for the right image display if two displays are used.

Therefore the invention has the following advantages: - an observer with special glasses can see stereoscopic images with small eye convergence and the eyes will not be fatigued; - by the polarizers the right eye only sees right images and left eye only sees left images; - an observer without special glasses can see normal (2D) images on left display or right display in contrast to prior stereoscopic display systems, wherein an observer without special glasses sees abnormal images as ghost images.

The left eye and right eye deflection means can be prisms which are applied to respective glass frames of the special glasses, i.e goggles.

Depending on the arrangement of the left and right images, the prisms are either adjoining each other with their sides of the smallest enclosed angle (angle of inclination), which means geometrically that the image rays from the left and right images cross each other. Further the prisms can be arranged adjoining each other on their leg sides with respect to the angle of inclination, so that the left image and right image are on the same sides as the left and right eye prisms. The same effects, like crossing rays or non-crossing rays, can also be effected by other deflection means, like mirrors or thelike.

Further the left eye image and right eye image can be depicted on two independent screens or on a single display screen if the display can be partioned in a suitable way. Preferably in the last case the display is a wide vision display (16 x 9 screen). The screens can be realised as projection areas, as liquid crystal displays (LCDs), as cathode ray tubes (CRT) or thelike.

To generate the stereoscopic impression, linear polarization or circular polarization of the light emitted from the images can be used.

According to the polarization used the stereoscopic display glasses comprises a left eye polarizer and a right eye polarizer respectively.

Preferred embodiments of the invention are now described with reference to the accompanying drawings, wherein Fig. 1 shows a schematic diagram of first embodiment of stereo display system using preferred embodiments of a display apparatus and a special glass, Fig. 2 shows a schematic diagram of a second embodiment of a stereoscopic display system, Fig. 3 shows a single display, Fig. 4 shows a stereoscopic display system according to the prior art, and Fig. 5 shows a second prior art stereoscopic display system.

Fig. 4 shows a known stereoscopic image viewing method, wherein an observer having a right eye 10 and a left eye 11 can see a stereoscopic image including aright image 2 for the right eye 10 and a left image 1 for the left eye 11 by binocular parallax. This system has image size limitation, because the human eye convergence cannot move over to the parallel direction. Due to the inter pupil distance of a human eyes of about 60 mm, the maximal left and right images widths can be about 60 mm.

Fig. 5 shows another prior stereoscopic image system, wherein an observer can see stereoscopic images by binocular parallax and crossing image rays. This system does not have image size limitation, but the convergence of the human eye is so large in this case, that the eye will be easily fatigued. Therefore it is not possible to see the stereoscopic image for a long time.

Fig. 1 shows a preferred embodiment of a stereo display system including glasses 3 and a stereoscopic display apparatus 20. The display apparatus 20 includes first display means 21 for displaying a left image 1 and includes also second display means 22 for displaying a right image 2.

The means 21, 22 are controlled by not shown means which generate the images to be displayed and which drive the means 21, 22 accordingly. The display means 21, 22 can be realised e.g. as LCD panels, as plasma panels, as projection means, or as other means known by a person skilled in the art.

In front of the means 21 there is provided a first display polarizer 13 and in front of the display means 22 there is provided a second polarizer 14.

In front of the display apparatus 20 there is provided a preferred embodiment of the special glasses 3. Basically the glasses 3 are in the form of goggles, wherein a left eye prism 4 and a right eye prism 5 are set on top of the left eye glass frame 8 and right eye glass frame 9 of the goggles. The front surfaces of the prisms 4, 5 are covered with a left eye polarizer 6 and a right eye polarizer 7, respectively. In this embodiment the prisms 4 and 5 are set on the frame glasses 8, 9 in such a way that the legs of the prism triangles are adjacent to each other.

The prisms 4, 5 of the special glasses 3 are arranged such that their legs are close to each other, so that the enclosed inclination angles of the prisms are located on the outside of the special glasses. In other words from left to right the inclination of the left eye prism 4 raises and from the middle of the special glasses 3 the inclination of the right eye prism 5 decreases. With these arrangement the left eye prism 4 receives left image rays 17 from the left display 21.

The left image 1 with its polarizer 13 is in this embodiment arranged on the side of the right eye 10, whereas the right image 2 with its polarizer 14 is arranged on the side of the left eye 11. In other words the right eye prism 5 receives the right eye image rays 16 from a right eye image 2 and its polarizer 14, wherein the right eye image 2 is arranged on the left side of the observer with his special glasses 3. Depicted are also the right eye 10 and the left eye 11. Therefore the right eye image rays 16 and the left eye image rays 17 are crossing some distance ahead of the special glasses 3. The polarization of the polarizers 13 and 14 for the left and right image 1, 2 are chosen in such a way as to fit to the polarizers 6, 7 of the respective prisms 4, 5.In other words, the polarization of the left picture polarizer 13 is identical to the polarization of the left eye prism polarizer 6, and the polarization of the right image polarizer 14 is identical to the polarization of the right prism polarizer 7.

Fig. 2 shows a second embodiment of a stereo display system. Here the orientations of the right eye and left eye prisms 4, 5 are changed, so that the respective legs of the prisms are now at the outside of the special glasses 3. In other words, the prisms are contacting in the middle of the goggles with their edges of the respective inclination angle. In this arrangement the left image 1 is on the left side, whereas the right image 2 is on the side of the right eye 10. Therefore, rays 17 of the left image and rays 16 of the right image do not cross in front of the special glasses 3.

The arrangement of the polarizers 13, 14, 4, 5 is the same as in the embodiment according to Fig. 2.

It may be mentioned that the polarizers 6, 7 can be also provided between the eye 11 and prism 4 or between the eye 10 and the prism 5, respectively. The polarizers 6, 7 may be attached directly to the prisms 6, 7, but they can also be hold with the aid of any other mechanical means as well known by a person skilled in the art. It is essential, that the polarizers 6, 7 are provided anywhere between the eyes and the images 1, 2.

Fig. 3 shows the possibility of using one single display 12 for the generation of the left image 1 and the right image 2. The display 12 may be realised e.g. by a LCD panel, a plasma panel, a cathode ray tube or thelike. When using a wide screen display, the screen of display 12 can be separated by image signal processing means, so that for example on the left half 18 of the display 12 the left image 1 is displayed, whereas on the right half 19 of the display 12 the right image 2 is displayed. To achieve the necessary polarization, the respective polarizers 13 and 14 are arranged in front of the display 12, which results in the generation of opposite polarization directions for the left and the right image.

Claims

1. Stereoscopic display apparatus (20) having first display means (21) for displaying a left image (1) and having second display means (22) for displaying a right image (2) and having a first polarizer (13) between said first display means (21) and a viewer and having a second polarizer (14) between said second display means (22) and said viewer, characterized in that said left image (1) is displayed in another area compared to the right image (2) and that said first polarizer (13) has a different polarization compared to said second polarizer (14).

2. Stereoscopic display apparatus according to claim 1, characterized in that said first display means (21) and/or said second display means (22) include a liquid crystal panel, a plasma panel and/or a cathode ray tube.

3. Stereoscopic display apparatus according to claim 1 or 2, characterized in that said first polarizer (13) and/or said second polarizer (14) are realised as linear or circular polarizer.

4. Stereoscopic display apparatus according to one of the claims 1 to 3, characterized in that said first display means (21) and said second display means (22) are realised as a single display means (12), which is controlled accordingly by image signal processing means.

5. Stereoscopic display glasses, characterized in that first deflection means (4) are provided which direct light-rays to a left eye (11) from a first direction, that second deflection means (5) are provided which direct light-rays to a right eye (10) from a second direction, that a third polarizer (6) is provided in the light ray path of said left eye (11), that a fourth polarizer (7) is provided in the light ray path of said right eye (10) and that said polarizers (6, 7) have different polarizations to eachother.

6. Stereoscopic display glasses according to claim 5, characterized in that said first deflection means (4) and/or said second deflection means (5) work with light refraction and/or reflection.

7. Stereoscopic display glasses according to claim 5 or 6, characterized in that said first deflection means (4) and/or said second deflection means (5) are realised as prism.

8. Stereoscopic display glasses according to claim 7, characterized in that said prisms (4, 5) are adjoining each other with their sides of their respective angle of inclination.

9. Stereoscopic display glasses according to one of the claims 7 to 8, characterized in that said prisms (4, 5) are adjoining each other with their respective legs.

10. Stereoscopic display glasses according to one of the claims 5 to 9, characterized in that said third polarizer (6) and/or said fourth polarizer are linear or circular polarizers.