| 摘要 |
PURPOSE:To facilitate making the device into an IC formation even if the number of keys is increased, by using a bipolar strobe signal, and strobing two keys with one strobe signal line and one key input information line. CONSTITUTION:A polarity indicating signal X is set to 1 to indicate the positive- polarity key strobe, and strobe indicating signals S0-S3 are transmitted successively from a CPU 3, and strobe signals D0-D3 are set to 1 successively in accordance with this transmission. Next, the signal X is set to 0 to indicate the negative-polarity key strobe, and signals S0-S3 are transmitted successively, signals D0-D3 are set to 0 successively. In this case, if keys divided by and C are depressed, only key information K0 goes to 1, but information K1-K3 are 0 when the signal D2 is 1. Only key information K3 is 0 but information K0-K2 are 1 when the signal D2 goes to 0. These information K0-K3 become read-in signals I0-I3 through a processing circuit 18 respectively and are given to the CPU 3, and it is detected that depressed keys are divided by and C. Thus, the two-fold number of keys is scanned. |
