Patent ID: 8144262

Claim:
A projection apparatus, connected to an external sensor for sensing a horizontal position of a user in front of a screen and for transmitting a horizontal position signal, for generating a first display frame, the projection apparatus comprising: a receiver for receiving the horizontal position signal; a processor for generating a second display frame according to the horizontal position signal and for superimposing the second display frame on the first display frame; and a frame projector for projecting the superimposed frame on the screen, wherein the second display frame is displayed on the user after the superimposed frame is projected; wherein the external sensor comprises a plurality of sensing elements being away from the projection apparatus to locate between the projection apparatus and the screen for generating an obstruction information, and then the external sensor converts the obstruction information into the horizontal position signal, and wherein the processor computes the horizontal position of the second display frame on the screen according to the horizontal position signal, and pre-determines the vertical position of the second display frame on the screen.