| 摘要 |
<p>One of three possible states of a device such as a switch (10) are encoded, utilizing only a single input line (22) from that device (10). The tri-state encoding circuit includes, in the case of a single-pole, double-throw switch (10), a first signal source (18) which feeds signals of like frequency and duty cycle, but 180 DEG out of phase to the respective fixed contacts (14, 16) of the switch. A first gating element (20) is interposed between a source of biasing signal and the movable contact (12) of the switch. Second and third gating elements (24, 26) receive control signals from the same or another signal source, these control signals being of like frequency and duty cycle but 180 DEG out of phase. These second control signals are also of the same frequency as the first control signals, but may have a different duty cycle. The second and third gating elements (24, 26) are responsive to these control signals for controlling application of the signal on the movable contact (12) to first and second associated outputs (A, B).</p> |
