JPS6455633A - Picture input signal generator - Google Patents

Abstract

PURPOSE:To surely detect a signal whose level is continuously changed, by counting a synchronizing signal generated at a prescribed timing to output the signal whose level is continuously changed or a signal whose level is changed at a single shot and recognizing an input signal as the picture input signal at the time of the change of the level of the input signal. CONSTITUTION:The synchronizing signal generated from a synchronizing signal sending means 43 provided in a picture control means 4A at a prescribed timing is outputted to a keyboard 2A. In the keyboard 2A, the synchronizing signal from the synchronizing signal sending means 43 is counted by a counting means 201 and the counting means 201 generates one signal whose level is continuously changed or two more signals which have levels continuously changed and are different in period. One signal or tow or more signals different in period from the counting means 201 or the signal whose level is changed at a single shot is selected and outputted by a selecting means 202. Thus, the continuously changed signal is surely detected.