| 摘要 |
<p>PURPOSE:To specify a position on a screen distantly from a large-sized display screen and the screen of a projection display device without any cord, by making the light wavelength of raster display different from the light wavelength of a light source for a marker. CONSTITUTION:All rasters on a display screen 16 are supplied to photodetector 32, whose output is inputted to a comparator 34 through an amplifying circuit 33. The comparator 34 is supplied to the output of a CRT controller 13. The circuit 33 performs processing so that the same output as the output of the controller 13 is obtained when the output of a marker device 18 is not supplied to the screen 16. An operator specifies a position 17 on the screen through the marker device 18 and when a raster comes to the specified position and the marker light source 24 turns on, the inputs to the comparator 34 have some difference and its output is sent out to a CPU12. The CPU12 receives the specified position input command of the screen from the operator. Namely, the screen position specified by the operator is detected.</p> |
