| 摘要 |
<p>PURPOSE:To improve operability, by monitoring the timing of a bright line detecting signal, and discriminating a designated CRT automatically, in a system for indicating a co-ordinate on the CRT by use of a light pen. CONSTITUTION:After detecting a light pen switching signal SW obtained when a light pen 9 is pressed on a CRT, a bright line detecting signal (l) of the light pen 9 is received only for a 1 field period, a co-ordinate detecting circuit 25 is operated, and a pulse AR for sampling an indicated co-ordinate area of the light pen 9 is inputted to a CRT discriminating circuit 27. From the CRT discriminating circuit 27, a CRT discriminating signal (h) is obtained by a detecting timing of this bright line detecting signal (l), and it is inputted to a write data controlling circuit 11 to make selective write to storage devices 3, 4 possible. Accordingly, which of plural CRTs 7, 8 is indicated by the light pen 9 is discriminated automatically.</p> |
