PROJECTION TYPE DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce the cost of a detector to detect an offset of convergence. SOLUTION: Detection mirrors 14-21 are placed around a screen 2 and ends of the screen 2 requiring a photo sensor 4 and the detection mirrors 14-21 reflect a pattern video image light to measure a convergence offset projected from cathode ray tubes 8, 9, 10, the photo sensor 4 placed at a prescribed position receives this reflected light to read position information of electron beams corresponding to each color and to detect the convergence offset.