Optics: image projectors – Stereoscopic
Reexamination Certificate
1999-02-20
2001-10-16
Dowling, William (Department: 2851)
Optics: image projectors
Stereoscopic
C353S098000, C359S478000, C359S479000
Reexamination Certificate
active
06302542
ABSTRACT:
BACKGROUND OF THE INVENTION
The parent invention of this current invention discloses a volumetric 3D display system that creates volumetric 3D images by projecting whole frames of 2D images created on a stationary projection device, through an optical-mechanical image delivery system, onto a moving screen (rotating or reciprocating). The system allows creation of volumetric 3D images using conventional 2D projection optics, without the need of collimated image beams. This current invention provides new mechanisms with improved motion smoothness and simplified structure.
In the prior arts, De Montebello disclosed a system using a rotating spiral screen to create a display space and a film projector to project 2D image frames onto the spiral screen [De Montebello 1969]. The depth of its display space is limited by the depth of focus of the projector and therefore is small. Morton described another system using a rotating helical screen to form a display space and using an anamorphic lens to accommodate the variation of focal distance from an image source to the surface of the helical screen [Morton 1990]. The anamorphic lens is difficult to make and complex to assemble. Its discrete nature can also compromise image quality. Another approach projects images composed of collimated light beams directly to a moving screen [Thompson 1996]. This usually requires a laser as the light source and hence can cost more than a projector-based system. Still another approach uses a stack of electrically switchable liquid crystal display layers [Hattori 1992, Sadovinik 1998]. Another approach uses a piezoelectric-based fast focusing lens to project image frames to a stack of switchable PDLC screens [Paek 1996]. Both approaches have limited resolution because the number of LCD panels or screens in the stack is physically limited.
SUMMARY OF THE INVENTION
This invention presents approaches with improved motion smoothness and simplified structure for volumetric 3D display by the Moving Screen Projection technique. A volumetric 3D display based on the Moving Screen Projection technique features three major portions:
(1) The moving screen: The periodically moving screen forms the display space and displays the projected images. Basically, there are two ways to sweep the screen over a space. The screen can be rotated or the screen can be reciprocated. For simplicity, these two approaches are termed as the Rotating Approach and the Reciprocating Approach respectively.
(2) The image delivery mechanism: The image delivery mechanism relays the optical image projected from the image projector onto the moving screen for displaying. The mechanism keeps the size and focus of the projected image frame invariant as the screen moves, and also keeps the orientation of the projected image frame synchronous to the moving screen. (Because direct whole-frame projection from the projector onto the screen is not possible due to the constant motion of the screen.) In the Rotating Approach, two improved mechanisms can be used. The first mechanism comprises a multi-mirror replay reflector rotating at half the speed of the rotating screen and a system of second relay reflectors rotating in synchronization with the screen, both with proper positioning with respect to the screen's angular position. The second mechanism comprises two switchable reflectors arranged at 90 degree, which also rotates at half the speed of the rotating screen and is properly positioned with respect to the screen's angular position. Each of the switchable reflectors can be switched to become reflective or transmissive. In the Reciprocating Approach, two types of improved mechanisms can be used. The first is the reciprocating reflector mechanism. A reflector system moving synchronously with the reciprocating screen but at a speed half of the screen speed is placed into the projection path between the image projector and the moving screen. This speed difference keeps the distance between the mirrored image of the projector, as viewed through the reciprocating reflector system, and the moving screen constant. The second mechanism is the zooming optics mechanism, which is capable of changing both the focus and the magnification of the projected 2D images in response to the reciprocating motion of the screen. The zooming optics can deliver the projected 2D images onto the moving screen in focus. It can also maintain or adjust the size of the projected image frames to create desired shape of display space.
(3) The image projector: The image projector generates and projects the set of 2D image frames, through the image delivery mechanism, onto the moving screen. The image projector generally consists of a image generating panel, a projection lens, and a light source.
REFERENCES:
patent: 3462213 (1969-08-01), DeMontebello
patent: 4670744 (1987-06-01), Buzak
patent: 4881068 (1989-11-01), Korevaar et al.
patent: 4922336 (1990-05-01), Morton
patent: 5082350 (1992-01-01), Garcia et al.
patent: 5148310 (1992-09-01), Batchko
patent: 5394202 (1995-02-01), Deering
patent: 5506597 (1996-04-01), Thompson et al.
patent: 5537251 (1996-07-01), Shimada
patent: 5678910 (1997-10-01), Martin
patent: 5764317 (1998-06-01), Sadovnik et al.
patent: 5954414 (1999-09-01), Tsao
Buzak, T.S. “A Field-sequential Discrete-depth-plane Three-dimensional Display”, SID International Symposium, vol. 16, pp. 345, 1985.
Downing, E. et al. “A Three-Color, Solid-State, Three-dimensional Display”, Science vol. 273, Aug. 30, 1996, pp. 1185.
Hattori, T. et al. 1992 “Spatial Modulation Display using Spatial Light Modulators”, Optical Engineering, vol. 31, No. 2 p. 350.
Paek, E.G. et al. “A 3D Projection Display using PDLCs”, presented at the Conference of the International Society for Optical Engineering, Jan. 29-Feb. 2, 1996, San Jose, CA.
Rawson, E.G. “Vibrating Varifocal Mirrors for 3-D Imaging”, IEEE Spectrum, Sep. 1969, pp. 37.
LandOfFree
Moving screen projection technique for volumetric... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Moving screen projection technique for volumetric..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Moving screen projection technique for volumetric... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2608316