| 摘要 |
<p>A battery powered keyboard entry device (1) includes an infra-red generator (14,15) for coupling the device to a processor (2) which includes an infra-red receiver (20). Each input binary signal is transmitted as a few (e.g. two or three) short infra-red pulses indicating the leading edge of the binary signal. In the receiver, the received groups of pulses, after detection and amplification, are stretched by a single-shot circuit (22) to produce binary signals of substantially the same length as the original binary signals. As each transmission is substantially shorter than each binary signal, power consumption in the keyboard entry device is substantially reduced as compared with a system in which the infra-red pulses for each input signal extend over the input signal length.</p> |
