| 摘要 |
<p>Geometric distortion in a scanning beam video laser projector, or the like, is corrected by comparing the time of arrival of the projection beam at a selected pixel on the projection screen with a predetermined time of arrival, and computing therefrom the changes in beam control required to remove the distortion. A peripheral portion (20) of the projected video field (18) is blank, being reserved for projection of bright beam alignment fiducials (32, 34) comprising selected pixels of the peripheral field portion. An optical sensor (22) is placed on the screen periphery so as to receive one pixel of each projected fiducial, its output being applied (through a light sensitive diode (400) to a beam control processor (42). Geometric distortion or a change in projector alignment shifts the beam time of arrival at the sensor (22). The processor (42) compares the time of arrival of the projector beam at each sensor (22) with a look-up table (44) and, from this comparison, determines the beam control corrections required to remove geometric distortion.</p> |
