Patent ID: 7692605

Claim:
Method of projecting images with correction of frame position error for a volumetric 3D display, the volumetric 3D display comprising a moving screen and being one of the following types: a. rotating screen system with optical interfacing unit, said moving screen rotating about an axis parallel to and passing through the screen surface, said optical interfacing unit rotating at half the speed of the screen; or b. rotating screen system without said optical interfacing unit, said moving screen rotating about an axis parallel to and passing through the screen surface; or c. rotary reciprocating system, said moving screen revolving about an axis and sweeping a volume while keeping the screen surface always facing a fixed direction, the system also comprising an interfacing reflector revolving in synchronization with the screen but about a second axis while keeping the reflector surface always facing a fixed direction, the method including the steps of: (1) providing a measure of position error of projected image frames, said position error being defined as actual deviation of center of a projected image frame with respect to its theoretical position, said measure of position error being a periodical function of angular position of said moving screen and covering a period of at least a. two rotations of said moving screen, if the volumetric 3D display being of the type of said rotating screen system with optical interfacing unit; or b. one rotation of said moving screen, if the volumetric 3D display being of the type of said rotating screen system without said optical interfacing unit; or c. one rotation of said moving screen, if the volumetric 3D display being of the type of said rotary reciprocating system; (2) determining a function of position correction of frame image for each image frame, said frame image being the non-blank image content in a corresponding image frame, said position correction being a position shift of said frame image with respect to center of the corresponding frame, said function of position correction being a periodical function of angular position of said moving screen with a period same as the period of said measure of position error; (3) shifting position of said frame image of each frame according to said function of position correction and projecting the corrected frames.