| 摘要 |
PURPOSE:To reduce noise and unnecessary radiation and to decrease the number of wirings between a switch group and a digital circuit 4, by constituting such a matrix that DC voltages are applied to key contacts. CONSTITUTION:Row lines 2a, 2b, 2c, and 2d of the key switch group 1 are connected to one terminal +V of a power source through resistances 5a, 5b, 5c, and 5d respectively. Further, the row lines 2a-2d are connected to input terminals of voltage comparators 6a-6d having a threshold voltage V1 and their outputs are connected to the input terminal part 4c of the digital circuit 4. Column lines 3a-3d, on the other hand, are connected to the other terminal G of the power source through resistance groups 7a, 7b, 7c, and 7d as well as the row lines 2 and further connected to the input terminal part 4D of the digital circuit 4 through voltage comparators 8a-8d. |
