| 摘要 |
<p>The system detects a variation in the capacity of the capacitor which is generally integrated in the oscillator circuit to verify the frequency of oscillation. The variation in the capacity of the capacitor, e.g. such as the presence of a hand, is detected by variation of the frequency of oscillation of the circuit. <??>The system is of the type in which the door opening mechanism is maintained in the closed position by a lock which is controlled by a door handle (10) and which means are provided for sensing the presence of a hand near to the door handle. The sensing system includes a transmitting antenna (24) on which is applied a periodic voltage, a receiving antenna (26), and a sensing circuit fitted with members for measuring the potential difference between the receiving antenna (26) and earth. The circuit also includes an amplitude comparator which compares the potential difference variation with an amplitude reference value (Aref).</p> |
