| 摘要 |
An image or pictorial scene generated by a raster scan is continuously maintained in proper alignment during normal operation of a visual display system by the use of photosensitive devices mounted to the display surface outside of the field of view. In the described embodiment, the photosensitive device is mounted in a position suitable for monitoring a selected retrace path of the raster scan pattern. During operation, the retrace of the raster is unblanked as it passes the photosensitive device such that elements of the photosensitive device are turned on. The output of the photosensitive elements are compared to signals representative of a properly positioned raster image, and differences between the stored signals and the received signals are then used to generate a correction signal in the feedback loop to vary the position of the moving energy beam such that the raster scan is properly aligned.
|
