| 摘要 |
PURPOSE:To perform an accurate key input decision, by setting the decision level of input of the 1st OR circuit lower or higher than that of the 2nd OR circuit according to whether the signal processor of a key matrix is based upon negative or positive logic. CONSTITUTION:Two-input OR gates 61-68 constituting the 1st OR circuit 2 are composed of TTLIC elements and an eight-input OR gate 7 constituting the 2nd OR circuit is composed to a C-MOSIC element. This C-MOSIC element has a higher threshold level than the TTLIC element, so the high/low decision level V2 of input of the gate 7 is set higher than the high/low decision level V1 of the gates 61-68. Consequently, A decision on a key input from a key matrix circuit 5 is performed by a shift signal 30 and a decision on a key input to a key contact K65 is performed by a key-scan signal KS and a key-return signal R0. |
