| 摘要 |
<p>PURPOSE:To use effectively the screen of a CRT by sensing a function selecting indicator lamp, which are provided on the outside of the face plate of the CRT, with a light pen synchronously with a display synchronizing signal. CONSTITUTION:A function display part 9 consisting of indicator lamps 91-98 is arranged on the outside of the face plate of a CRT8 to display functions. A function designation processing part 7 uses horizontal and vertical flyback periods to light indicator lamps 91-98 of the function display part 9 on a basis of the synchronizing signal supplied from a display control part 6. When one of indicator lamps 91-98 is hit by a light pen 2, the photodetection signal due to the light pen 2 and the synchronizing signal are compared with each other to recognize the position of the hit indicator lamp, and a function designating signal corresponding to this indicator lamp is sent to a host computer 4.</p> |
