| 摘要 |
<p>PURPOSE:To reduce the number of input lines to half, by connecting commonly two input lines which connect diodes in different directions and interposing an A/D converter between their common connection point and a central controller. CONSTITUTION:Two input lines, which connect diodes D1-D6 in series in different conduction directions, out of input lines of columns or rows of a matrix are connected commonly, and an A/D converter 5 is interposed between the common connection point and a central controller 4. When signals of parts X and Y are outputted, a depressed key is discriminated, and a voltage waveform corresponding to the state of a keyboard is outputted from keyboard driving terminals O1-O3 of the central controller 4.</p> |
