| 摘要 |
<p>PURPOSE:To avoid the overlap of graphic owing to the simultaneous use of plural uses by inhibiting acceptance of other inputs in case a signal showing a using request is supplied from a tablet. CONSTITUTION:In case no tablet is used, the timer output 100 of a timer circuit 4 is set at '1' and a switch control circuit 3 accepts a request signal and sends it to a switching circuit 2. The circuit 2 connects a data signal line 103 of a tablet 1-1 to a data signal line 104 of an electronic blackboard device by a switching signal. Then the circuit 2 sends a connection answer signal 105 back to the tablet 1-1 to switch on a connection pilot lamp. The circuit 3 accepts no request from other tablets when the output 100 is equal to '0' and therefore sends a connection unable answer signal 106 and displays this transmission by a pilot lamp in case a request signal is given from another tablet 1-n.</p> |
